Resource Cluster-Based Resource Search and Allocation Scheme for Vehicular Clouds in Vehicular Ad Hoc Networks.

Vehicular clouds represent an appealing approach, leveraging vehicles' resources to generate value-added services. Thus, efficiently searching for and allocating resources is a challenge for the successful construction of vehicular clouds. Many recent schemes have relied on hierarchical network architectures using clusters to address this challenge. These clusters are typically constructed based on vehicle proximity, such as being on the same road or within the same region. However, this approach struggles to rapidly search for and consistently allocate resources, especially considering the diverse resource types and varying mobility of vehicles. To address these limitations, we propose the Resource Cluster-based Resource Search and Allocation (RCSA) scheme. RCSA constructs resource clusters based on resource types rather than vehicle proximity. This allows for more efficient resource searching and allocation. Within these resource clusters, RCSA supports both intra-resource cluster search for the same resource type and inter-resource cluster search for different resource types. In RCSA, vehicles with longer connection times and larger resource capacities are allocated in vehicular clouds to minimize cloud breakdowns and communication traffic. To handle the reconstruction of resource clusters due to vehicle mobility, RCSA implements mechanisms for replacing Resource Cluster Heads (RCHs) and managing Resource Cluster Members (RCMs). Simulation results validate the effectiveness of RCSA, demonstrating its superiority over existing schemes in terms of resource utilization, allocation efficiency, and overall performance.

Press Conduction Welding for Secondary Bonding of Aircraft Skin/Stiffener Assemblies Using Carbon Fiber/PEKK Thermoplastic Composites and PEI Adhesive.

This study investigates the secondary bonding of aircraft skin/stiffener assemblies using press conduction welding with carbon fiber/polyetherketoneketone thermoplastic composites and polyetherimide adhesive. Recognizing the challenges posed by conventional welding methods in maintaining material integrity and uniformity, this research explores an alternative methodology that mitigates these issues while ensuring high-strength bonds. The press conduction welding parameters were selected based on single-lap shear tests and applied in the bonding of skin and omega stiffener components. The temperature range was determined using differential scanning calorimetry. The pressure was held at 1 MPa for 180 s. The welding temperature that produced a high-bonding strength was identified experimentally; these key variables were then used in the welding process of the skin and omega stiffener. By analyzing how the fibers tear and the effectiveness of interdiffusion between the plies, we were able to gain insights into the bonding strength and fractured surface. The findings suggest that press conduction welding provides a viable route for secondary bonding in thermoplastic composite structures, highlighting its advantages in terms of processing efficiency and integrity. This study contributes to the understanding of the mechanical behaviors of bonded joints and underscores the significance of temperature control in the welding process.

Enhanced performance of lead sulfide quantum dot-sensitized solar cells by controlling the thickness of metal halide perovskite shells.

The metal halide perovskite CH3NH3PbI3 (MAP) can be applied as the shell layer of lead sulfide quantum dots (PbS QDs) for improving solar power conversion efficiency. However, basic physics for this PbS core/MAP shell QD system is still unclear and needs to be clarified to further improve efficiency. Therefore, in this study, we investigate how MAP shell thickness affects device performance and dynamics of charge carriers for PbS QD-sensitized solar cells. Covering the PbS QDs with the MAP shell layers of an appropriate thickness around 0.34 nm greatly suppresses charge carrier recombination at surface defects along with improved carrier transport to neighboring oxide and polymer layers. Therefore, this MAP shell thickness provides the highest open-circuit voltage, short-circuit current density, and fill factor for solar cells. Overall power conversion efficiencies of these solar cells reached about 4.1%, which is about six-fold higher than that for solar cells without MAP (about 0.7%). Additionally, use of the MAP shell layers can prevent oxidation of PbS QDs and, therefore, makes a degradation of solar cell performance slower in air.

The Effect of Porosity on the Thermal Conductivity of Highly Thermally Conductive Adhesives for Advanced Semiconductor Packages.

This study suggests promising candidates as highly thermally conductive adhesives for advanced semiconductor packaging processes such as flip chip ball grid array (fcBGA), flip chip chip scale package (fcCSP), and package on package (PoP). To achieve an extremely high thermal conductivity (TC) of thermally conductive adhesives of around 10 Wm-1K-1, several technical methods have been tried. However, there are few ways to achieve such a high TC value except by using spherical aluminum nitride (AlN) and 99.99% purified aluminum oxide (Al2O3) fillers. Herein, by adapting highly sophisticated blending and dispersion techniques with spherical AlN fillers, the highest TC of 9.83 Wm-1K-1 was achieved. However, there were big differences between theoretically calculated TCs that were based on the conventional Bruggeman asymmetric model and experimentally measured TCs due to the presence of voids or pores in the composites. To narrow the gaps between these two TC values, this study also suggests a new experimental model that contains the porosity effect on the effective TC of composites in high filler loading ranges over 80 vol%, which modifies the conventional Bruggeman asymmetric model.

Multiple Precaching Vehicle Selection Scheme Based on Set Ranking in Intermittently Connected Vehicular Networks.

In vehicular networks, vehicles download vehicular information for various applications, including safety, convenience, entertainment, and social interaction, from the corresponding content servers via stationary roadside units. Since sufficient RSUs might be difficult to deploy due to rough geographical conditions or high deployment costs, vehicular networks can feature uncovered outage zones between two neighboring RSUs. In these outage zones, vehicles cannot download content, and thus the vehicle networks are defined as intermittently connected vehicular networks. In intermittently connected vehicular networks, the download delay and traffic overhead on the backhaul links are increased due to the large size of the content requested by vehicle users and the long distances between RSUs. Using the mobility information of vehicles, several schemes have been proposed to solve this issue by precaching and relaying content via multiple relaying vehicles in the outage zone. However, because they involved the individual ranking of vehicles for precaching and allocated all of the available precaching amounts to the top-ranking vehicles, they decreased the success rate of content requests and the fairness of vehicle precaching. To overcome the problem of these previous schemes, this paper proposes a multiple precaching vehicle selection (MPVS) scheme that efficiently selects a content-precaching vehicle group with multiple precaching vehicles to precache relayed content in outage zones. To achieve this, we first designed numerical models to decide the necessity and the amount of precaching and to calculate the available precaching amounts of vehicles. Next, MPVS calculates all available vehicle sets and ranks each set based on the available precaching amount. Then, the content-precaching vehicle group is identified from the sets by considering both set rankings and vehicle communication overheads. MPVS also provides a content downloading process through the content-precaching vehicle group in the outage zone. Simulation results conducted in various environments with a content request model and a highway mobility model verified that MPVS was superior to a representative previous scheme.

Intraoperative zoom lens calibration for high magnification surgical microscope.

BACKGROUND AND OBJECTIVES: An augmented reality (AR)-based surgical guidance system is often used with high-magnification zoom lens systems such as a surgical microscope, particularly in neurology or otolaryngology. To superimpose the internal structures of relevant organs on the microscopy image, an accurate calibration process to obtain the camera intrinsic and hand-eye parameters of the microscope is essential. However, conventional calibration methods are unsuitable for surgical microscopes because of their narrow depth of focus at high magnifications. To realize AR-based surgical guidance with a high-magnification surgical microscope, we herein propose a new calibration method that is applicable to the highest magnification levels as well as low magnifications. METHODS: The key idea of the proposed method is to find the relationship between the focal length and the hand-eye parameters, which remains constant regardless of the magnification level. Based on this, even if the magnification changes arbitrarily during surgery, the intrinsic and hand-eye parameters are recalculated quickly and accurately with one or two pictures of the pattern. We also developed a dedicated calibration tool with a prism to take focused pattern images without interfering with the surgery. RESULTS: The proposed calibration method ensured an AR error of < 1 mm for all magnification levels. In addition, the variation of focal length was within 1% regardless of the magnification level, and the corresponding variation with the conventional calibration method exceeded 20% at high magnification levels. CONCLUSIONS: The comparative study showed that the proposed method has outstanding accuracy and reproducibility for a high-magnification surgical microscope. The proposed calibration method is applicable to various endoscope or microscope systems with zoom lens.

Implicit Overhearing Node-Based Multi-Hop Communication Scheme in IoT LoRa Networks.

Long range (LoRa) is a low-power wide-area technology because it is eminent for robust long-distance, low-bitrate, and low-power communications in the unlicensed sub-GHz spectrum used for the Internet of things (IoT) networks. Recently, several multi-hop LoRa networks have proposed schemes with explicit relay nodes to partially mitigate the path loss and longer transmission time bottlenecks of the conventional single-hop LoRa by focusing more on coverage expansion. However, they do not consider improving the packet delivery success ratio (PDSR) and the packet reduction ratio (PRR) by using the overhearing technique. Thus, this paper proposes an implicit overhearing node-based multi-hop communication (IOMC) scheme in IoT LoRa networks, which exploits implicit relay nodes for performing the overhearing to promote relay operation while satisfying the duty cycle regulation. In IOMC, implicit relay nodes are selected as overhearing nodes (OHs) among end devices with a low spreading factor (SF) in order to improve PDSR and PRR for distant end devices (EDs). A theoretical framework for designing and determining the OH nodes to execute the relay operations was developed with consideration of the LoRaWAN MAC protocol. Simulation results verify that IOMC significantly increases the probability of successful transmission, performs best in high node density, and is more resilient to poor RSSI than the existing schemes.

Effects of a Metacognitive Smartphone Intervention With Weekly Mentoring Sessions for Individuals With Schizophrenia: A Quasi-Experimental Study.

Application (app)-based interventions using smartphones could provide effective alternatives to traditional treatment programs during and beyond the coronavirus disease 2019 pandemic. The current quasi-experimental study with a non-equivalent comparison group tested the effects of a smartphone app-based metacognitive intervention program with weekly mentoring sessions on the meta-cognitive beliefs, psychotic symptoms, and social functioning of individuals with schizophrenia from community psychosocial rehabilitation centers. The study was conducted with 20 participants with severe psychotic symptoms and low social functioning and 24 participants with relatively light psychotic symptoms and good social functioning as a comparison group. For the experimental group, the app-based intervention was combined with weekly contact mentoring sessions over 10 weeks. The comparison group received only the app-based intervention over 10 weekly sessions. No differences were observed between groups' total scores; however, the experimental group showed a tendency toward improved psychotic symptoms and social functioning over time, unlike the comparison group. These findings provide an empirical basis for managing schizophrenia symptoms with smartphone apps. [Journal of Psychosocial Nursing and Mental Health Services, 61(2), 27-37.].

SF-Partition-Based Clustering and Relaying Scheme for Resolving Near-Far Unfairness in IoT Multihop LoRa Networks.

Long range (LoRa) is one of the most successful low-power wide-area networking technologies because it is ideally suited for long-distance, low-bit rate, and low-power communications in the unlicensed sub-GHz spectrum utilized for Internet of things (IoT) networks. The effectiveness of LoRa depends on the link budget (i.e., spreading factor (SF), bandwidth (BW), and transmission power (TX)). Due to the near-far effect, the allocation of a link budget to LoRa devices (LDs) in large coverage regions is unfair between them depending on their distance to the GW. Thus, more transmission opportunities are given to some LDs to the detriment of other LD's opportunities. Numerous studies have been conducted to address the prevalent near-far fairness problem. Due to the absence of a tractable analytical model for fairness in the LoRa network, however, it is still difficult to solve this problem completely. Thus, we propose an SF-partition-based clustering and relaying (SFPCR) scheme to achieve enormous LD connectivity with fairness in IoT multihop LoRa networks. For the SF partition, the SFPCR scheme determines the suitable partitioning threshold point for bridging packet delivery success probability gaps between SF regions, namely, the lower SF zone (LSFZ) and the higher SF zone (HSFZ). To avoid long-distance transmissions to the GW, the HSFZ constructs a density-based subspace clustering that generates clusters of arbitrary shape for adjacent LDs and selects cluster headers by using a binary score representation. To support reliable data transmissions to the GW by multihop communications, the LSFZ offers a relay LD selection that ideally chooses the best relay LD to extend uplink transmissions from LDs in the HSFZ. Through simulations, we show that the proposed SFPCR scheme exhibits the highest success probability of 65.7%, followed by the FSRC scheme at 44.6%, the mesh scheme at 34.2%, and lastly the cluster-based scheme at 29.4%, and it conserves the energy of LDs compared with the existing schemes.

Highly-packed self-assembled graphene oxide film-integrated resistive random-access memory on a silicon substrate for neuromorphic application.

Resistive random-access memories (RRAMs) based on metal-oxide thin films have been studied extensively for application as synaptic devices in neuromorphic systems. The use of graphene oxide (GO) as a switching layer offers an exciting alternative to other materials such as metal-oxides. We present a newly developed RRAM device fabricated by implementing highly-packed GO layers on a highly doped Si wafer to yield a gradual modulation of the memory as a function of the number of input pulses. By using flow-enabled self-assembly, highly uniform GO thin films can be formed on flat Si wafers in a rapid and simple process. The switching mechanism was explored through proposed scenarios reconstructing the density change of the sp2cluster in the GO layer, resulting in a gradual conductance modulation. We analyzed that the current in a low resistance state could flow by tunneling or hopping via clusters because the distance between the sp2clusters in closely-packed GO layers is short. Finally, through a pattern-recognition simulation with a Modified National Institute of Standards and Technology database, the feasibility of using close-packed GO layers as synapse devices was successfully demonstrated.

Video Packet Distribution Scheme for Multimedia Streaming Services in VANETs.

By leveraging the development of mobile communication technologies and due to the increased capabilities of mobile devices, mobile multimedia services have gained prominence for supporting high-quality video streaming services. In vehicular ad-hoc networks (VANETs), high-quality video streaming services are focused on providing safety and infotainment applications to vehicles on the roads. Video streaming data require elastic and continuous video packet distributions to vehicles to present interactive real-time views of meaningful scenarios on the road. However, the high mobility of vehicles is one of the fundamental and important challenging issues for video streaming services in VANETs. Nevertheless, previous studies neither dealt with suitable data caching for supporting the mobility of vehicles nor provided appropriate seamless packet forwarding for ensuring the quality of service (QoS) and quality of experience (QoE) of real-time video streaming services. To address this problem, this paper proposes a video packet distribution scheme named Clone, which integrates vehicle-to-vehicle and vehicle-to-infrastructure communications to disseminate video packets for video streaming services in VANETs. First, an indicator called current network quality information (CNQI) is defined to measure the feature of data forwarding of each node to its neighbor nodes in terms of data delivery ratio and delay. Based on the CNQI value of each node and the trajectory of the destination vehicle, access points called clones are selected to cache video data packets from data sources. Subsequently, packet distribution optimization is conducted to determine the number of video packets to cache in each clone. Finally, data delivery synchronization is established to support seamless streaming data delivery from a clone to the destination vehicle. The experimental results show that the proposed scheme achieves high-quality video streaming services in terms of QoS and QoE compared with existing schemes.

The Effect of Three Surgical Therapies to Increase Keratinized Mucosa Surrounding Dental Implants with Peri-Implantitis: A Pilot Study.

Background and Objectives: The purpose of this pilot study was to evaluate the clinical outcomes of three different methods for increasing the keratinized mucosa (KM) surrounding dental implants with peri-implantitis. Materials and methods: Twenty implant sites with peri-implantitis were divided into: (1) porcine collagen matrix (CM) group: seven implant sites; (2) apically positioned flap (APF) group: eight implant sites; and (3) free gingival graft (FGG) group: five implant sites. The KM width and clinical parameters (probing pocket depth (PPD) and bleeding on probing (BOP)) were measured at time points: before surgery (T0) and 30 (T1), 60 (T2), 90 (T3), and 180 (T4) days after surgery. Results: Regarding KM width, all the groups had significant differences for increasing horizontal and vertical KM width. The CM and FGG groups had greater KM than the APF group. There was a decrease in PPD in all three groups. APF and FGG showed significant differences in PPD at T1 and T2 compared to T0. Only the FGG group showed a significant difference in PPD at T3 and T4 compared with that at T0. BOP values were also reduced in all the groups at T1-T4 compared to T0. The APF and FGG groups showed a significant decrease in BOP. Conclusions: Three surgical therapies presented favorable results for increasing the KM surrounding implants. Compared with the FGG group, the CM showed similar results in increasing the KM around the dental implants with peri-implantitis.

Evaluating Change of Marginal Bone Height with Cone-Beam Computed Tomography Following Surgical Treatment with Guided Tissue Regeneration (Bone Grafting) or Access Flap Alone: A Retrospective Study.

Background and Objectives: This study aimed to evaluate the change of bone height following treatment of human intrabony defects with guided tissue regeneration (GTR) with bone grafting or access flap alone by cone-beam computed tomography (CBCT) scan. Materials and methods: This study was conducted as a retrospective longitudinal study. In this study, a total of 2281 teeth sites were included: the GTR group had 1210 sites, and the Flap group had 1071 sites. In the GTR group, demineralized freeze-dried bone (DFDBA) particles in combination with resorbable collagen membrane were used. No regenerative material was applied to the Flap group. CBCT images were taken twice at baseline and at least 2.5 months postoperatively. Bone heights were measured using software on CBCT images. Results: The bony change between the GTR and Flap groups was significantly different (p = 0.00001). Both males and females in the GTR group had smaller bone loss than in the Flap group. In age groups, significant differences of bony height between the GTR and Flap groups were observed in the subgroups consisting of those 29-45 and 46-53 years old. The non-smoking subjects in the GTR group had higher bone heights than those in the Flap group. In the absence of systemic disease and medicine, bone formation was higher in the GTR group than in the Flap group. In terms of oral position, the #14-17, #34-37, and #44-47 subgroups of the GTR group showed higher levels of bone heights than those of the Flap group. Conclusions. The results of this study indicated that the GTR procedure offers the additional benefit of higher bone heights than the Flap procedure does.

Adaptive Content Precaching Scheme Based on the Predictive Speed of Vehicles in Content-Centric Vehicular Networks.

Content-Centric Vehicular Networks (CCVNs) are considered as an attractive technology to efficiently distribute and share contents among vehicles in vehicular environments. Due to the large size of contents such as multimedia data, it might be difficult for a vehicle to download the whole of a content within the coverage of its current RoadSide Unit (RSU). To address this issue, many studies exploit mobility-based content precaching in the next RSU on the trajectory of the vehicle. To calculate the amount of the content precaching, they use a constant speed such as the current speed of the vehicle requesting the content or the average speed of vehicles in the next RSU. However, since they do not appropriately reflect the practical speed of the vehicle in the next RSU, they could incorrectly calculate the amount of the content precaching. Therefore, we propose an adaptive content precaching scheme (ACPS) that correctly estimates the predictive speed of a requester vehicle to reflect its practical speed and calculates the amount of the content precaching using its predictive speed. ACPS adjusts the predictive speed to the average speed starting from the current speed with the optimized adaptive value. To compensate for a subtle error between the predictive and the practical speeds, ACPS appropriately adds a guardband area to the precaching amount. Simulation results verify that ACPS achieves better performance than previous schemes with the current or the average speeds in terms of the content download delay and the backhaul traffic overhead.

Metacognitive Rating Scale: A Study Applying a Korean Translation to Individuals with Schizophrenia.

Metacognition is a higher-level cognition of identifying one's own mental status, beliefs, and intentions. This research comprised a survey of 184 people with schizophrenia to verify the reliability of the metacognitive rating scale (MCRS) with the revised and supplemented metacognitions questionnaire (MCQ) to measure the dysfunctional metacognitive beliefs of people with schizophrenia by adding the concepts of anger and anxiety. This study analyzed the data using principal component analysis and the varimax method for exploratory factor analysis. To examine the reliability of the extracted factors, Cronbach's α was used. According to the results, reliability was ensured for five factors: positive beliefs about worry, negative beliefs about uncontrollability and danger of worry, cognitive confidence, need for control, and cognitive self-consciousness. The negative beliefs about uncontrollability and danger of worry and the need for control on anger expression, which were both added in this research, exhibited the highest correlation (r = 0.727). The results suggest that the MCRS is a reliable tool to measure the metacognition of people with schizophrenia.

Transparent Electromagnetic Shielding Film Utilizing Imprinting-Based Micro Patterning Technology.

Utilization of methods involving component integration has accelerated, owing to the growth of the smart mobile industry. However, this integration leads to interference issues between the components, thereby elucidating the importance of the electromagnetic interference (EMI) shielding technology to solve such issues. EMI shielding technology has been previously implemented via the reflection or absorption of electromagnetic waves by using conductive materials. Nevertheless, to tackle the recent changes in the industry, a transparent and flexible EMI shielding technology is necessitated. In this study, a transparent and flexible EMI shielding material was fabricated by filling a conductive binder in a film comprising an intaglio pattern; this was achieved by using the ultraviolet (UV) imprinting technology to realize mass production. Subsequently, changes in the aperture ratio and shielding characteristics were analyzed according to the structure of the pattern. Based on this analysis, a square pattern was designed and a film with an intaglio pattern was developed through a UV imprinting process. Furthermore, it was confirmed that the transmittance, conductivity, and EMI shielding rate of the film were altered while changing the coating thickness of the conductive particles in the intaglio pattern. The final film prepared in this study exhibited characteristics that satisfied the required EMI shielding performance for electric and electronic applications, while achieving flexible structural stability and transparency.

Navigation-assisted anchor insertion in shoulder arthroscopy: a validity study.

BACKGROUND: This study aimed to compare conventional and navigation-assisted arthroscopic rotator cuff repair in terms of anchor screw insertion. METHODS: The surgical performance of five operators while using the conventional and proposed navigation-assisted systems in a phantom surgical model and cadaveric shoulders were compared. The participating operators were divided into two groups, the expert group (n = 3) and the novice group (n = 2). In the phantom model, the experimental tasks included anchor insertion in the rotator cuff footprint and sutures retrieval. A motion analysis camera system was used to track the surgeons' hand movements. The surgical performance metric included the total path length, number of movements, and surgical duration. In cadaveric experiments, the repeatability and reproducibility of the anchor insertion angle were compared among the three experts, and the feasibility of the navigation-assisted anchor insertion was validated. RESULTS: No significant differences in the total path length, number of movements, and time taken were found between the conventional and proposed systems in the phantom model. In cadaveric experiments, however, the clustering of the anchor insertion angle indicated that the proposed system enabled both novice and expert operators to reproducibly insert the anchor with an angle close to the predetermined target angle, resulting in an angle error of < 2° (P = 0.0002). CONCLUSION: The proposed navigation-assisted system improved the surgical performance from a novice level to an expert level. All the experts achieved high repeatability and reproducibility for anchor insertion. The navigation-assisted system may help surgeons, including those who are inexperienced, easily familiarize themselves to of suture anchors insertion in the right direction by providing better guidance for anchor orientation. LEVEL OF EVIDENCE: A retrospective study (level 2).

Thermal Conductivity and Electromagnetic Interference (EMI) Absorbing Properties of Composite Sheets Composed of Dry Processed Core-Shell Structured Fillers and Silicone Polymers.

This paper proposes dual-functional sheets (DFSs) that simultaneously have high thermal conductivity (TC) and electromagnetic interference (EMI) absorbing properties, making them suitable for use in mobile electronics. By adopting a simple but highly efficient dry process for manufacturing core-shell structured fillers (CSSFs) and formulating a close-packed filler composition, the DFSs show high performance, TC of 5.1 W m-1 K-1, and a -4 dB inter-decoupling ratio (IDR) at a 1 GHz frequency. Especially, the DFSs show a high dielectric breakdown voltage (BDV) of 3 kV mm-1, which is beneficial for application in most electronic devices. The DFSs consist of two kinds of CSSFs that are blended in accordance with the close-packing rule, Horsfield's packing model, and with polydimethylsiloxane (PDMS) polymers. The core materials are soft magnetic Fe-12.5%Cr and Fe-6.5%Si alloy powders of different sizes, and Al2O3 ceramic powders of a 1-µm diameter are used as the shell material. The high performance of the DFS is supposed to originate from the thick and stable shell layer and the maximized filler loading capability owing to the close-packed structure.

Compact Bone Surgery Robot With a High-Resolution and High-Rigidity Remote Center of Motion Mechanism.

OBJECTIVE: Two important and difficult tasks during a bone drilling procedure are guiding the orientation of the drilling axis toward the target and maintaining the orientation against the drilling force. To accomplish these tasks, a remote center of motion (RCM) mechanism is adopted to align the orientation of the drilling axis without changing the entry point. However, existing RCM mechanisms do not provide sufficient resolution and rigidity to address hard tissue cases. METHODS: We propose a new type of RCM mechanism that uses two sets of linear actuators and a gearless-arc guide to have a high resolution and rigidity. In addition, we designed a single motor-based drilling mechanism based on rolling friction. To achieve automatic control of the guiding and drilling process, we incorporated a computer-tomography-based navigation system that was equipped with an optical tracking system. RESULTS: The effectiveness of the integrated robotic system was demonstrated through a series of experiments and ex vivo drilling tests on swine femurs. The proposed robotic system withstood a maximum external force of 51 N to maintain the joint angle, and the average drilling error was less than 1.2 mm. CONCLUSION: This study confirms the feasibility of the proposed bone drilling robotic system with a high-resolution and high-rigidity RCM mechanism. SIGNIFICANCE: This drilling system is the first successful trial based on an RCM mechanism and a single motor-based drilling mechanism, reducing the footprint and required motors with respect to previous bone surgical robots.

Navigation-assisted suture anchor insertion for arthroscopic rotator cuff repair.

BACKGROUND: Suture anchor placement for subscapularis repair is challenging. Determining the exact location and optimum angle relative to the subscapularis tendon direction is difficult because of the mismatch between a distorted arthroscopic view and the actual anatomy of the footprint. This study aimed to compare the reliability and reproducibility of the navigation-assisted anchoring technique with conventional arthroscopic anchor fixation. METHODS: Arthroscopic shoulder models were tested by five surgeons. The conventional and navigation-assisted methods of suture anchoring in the subscapularis footprint on the humeral head were tested by each surgeon seven times. Angular results and anchor locations were measured and compared using the Wilcoxon signed rank test. Interobserver intraclass correlation coefficients (ICCs) were analyzed among the surgeons. RESULTS: The mean angular errors of the targeted anchor fixation guide without and with navigation were 17° and 2° (p < 0.05), respectively, and the translational errors were 15 and 3 mm (p < 0.05), respectively. All participants showed a narrow range of anchor fixation angular and translational errors from the original target. Among the surgeons, the interobserver reliabilities of angular errors for ICCs of the navigation-assisted and conventional methods were 0.897 and 0.586, respectively, and the interobserver ICC reliabilities for translational error were 0.938 and 0.619, respectively. CONCLUSIONS: The navigation system may help surgeons be more aware of the surrounding anatomy and location, providing better guidance for anchor orientation, including footprint location and anchor angle.