Optimising computer vision-based ergonomic assessments: sensitivity to camera position and monocular 3D pose model.

Numerous computer vision algorithms have been developed to automate posture analysis and enhance the efficiency and accuracy of ergonomic evaluations. However, the most effective algorithm for conducting ergonomic assessments remains uncertain. Therefore, the aim of this study was to identify the optimal camera position and monocular 3D pose model that would facilitate precise and efficient ergonomic evaluations. We evaluated and compared four currently available computer vision algorithms: Mediapipe BlazePose, VideoPose3D, 3D-pose-baseline, and PSTMO to determine the most suitable model for conducting ergonomic assessments. Based on the findings, the side camera position yielded the lowest Mean Absolute Error (MAE) across static, dynamic, and combined tasks. This positioning proved to be the most reliable for ergonomic assessments. Additionally, VP3D_FB demonstrated superior performance among evaluated models.Practitioner Summary: This study aimed to determine the most effective computer vision algorithm and camera position for precise and efficient ergonomic evaluations. Evaluating four algorithms, we found that the side camera position with VideoPose3D yielded the lowest Mean Absolute Error (MAE), ensuring precise and efficient evaluations.

Measurement of Nasalance Scores Without Touching the Philtrum for Better Comfort During Speech Assessment and Therapy: A Preliminary Study.

OBJECTIVE: The Kay Pentax nasometer uses a separator plate that touches the philtrum of a patient to separate the nasal and oral sound energies for nasalance measurement. However, the separator plate can restrict the natural movement of the patient's upper lip and generate unpleasant pressure on the patient's philtrum. The present study was intended to measure nasalance scores without touching the philtrum for better comfort during speech assessment and therapy. METHODS: Nasalance scores of 10 males and 10 females having no speech disorders were measured under 4 levels (0, 5, 10, and 15 mm) of the gap between the plate and the philtrum (denoted as plate-to-philtrum gap) using Nasometer II 6450 for nasal (Nasal Sentences) and oral (Zoo Passage) stimuli. Regression formulas were established to examine the relationships between nasalance score and plate-to-philtrum gap for the stimuli. To provide nasalance scores equivalent to those measured for the contact condition, compensation factors for the 5 mm plate-to-philtrum gap measurement condition were identified for the stimuli. RESULTS: The nasalance scores were significantly different between the 4 different plate-to-philtrum gaps for the stimuli. Compensation factors for the Nasal Sentences and the Zoo Passage were identified as 1.17 and 0.71, respectively. CONCLUSIONS: The 5 mm plate-to-philtrum gap condition after multiplying the compensation factors can provide equivalent nasalance scores to the conventional contact measurement condition which may provide better comfort in speech assessment and therapy.

Effects of a Motion Seat System on Driver's Passive Task-Related Fatigue: An On-Road Driving Study.

Passive task-related (TR) fatigue caused by monotonous driving can negatively affect driving safety by impairing driver alertness and performance. This study aims to evaluate the effectiveness of a motion seat system on the driver's passive TR fatigue in terms of driving performance, physiological response, and subjective fatigue by using automotive and physiological sensors those applicable to on-road driving environment. Twenty drivers (5 females and 15 males; age = 38.5 ± 12.2) with more than two years of driving experience participated in an on-road experiment with two driving conditions: driving in the static seat condition during the first half of the driving session and then in the static (static-static, SS) or motion seat (static-motion, SM) condition during the second half. The SM condition showed significantly lower passive TR fatigue by 4.4~56.5% compared to the SS condition in terms of the standard deviation of velocity, percentage of eyelid closure rate (PERCLOS), and the ratio of low- to high-frequency power (LF/HF) of electrocardiography signals. The drivers rated significantly lower subjective state changes of overall fatigue, mental fatigue, passive TR fatigue, drowsiness, and decreased concentration in the SM condition than those in the SS condition. The findings of the study support the use of a motion seat system can be an effective countermeasure to reduce passive TR fatigue.

Development of an Ultrasonic Doppler Sensor-Based Swallowing Monitoring and Assessment System.

Existing swallowing evaluation methods using X-ray or endoscopy are qualitative. The present study develops a swallowing monitoring and assessment system (SMAS) that is nonintrusive and quantitative. The SMAS comprises an ultrasonic Doppler sensor array, a microphone, and an inertial measurement unit to measure ultrasound signals originating only from swallowing activities. Ultrasound measurements were collected for combinations of two viscosity conditions (water and yogurt) and two volume conditions (3 mL and 9 mL) from 24 healthy participants (14 males and 10 females; age = 30.5 ± 7.6 years) with no history of swallowing disorders and were quantified for 1st peak amplitude, 2nd peak amplitude, peak-to-peak (PP) time interval, duration, energy, and proportion of two or more peaks. The peak amplitudes and energy significantly decreased by viscosity and the PP time interval and duration increased by volume. The correlation between the time measures were higher (r = 0.78) than that of the amplitude measures (r = 0.30), and the energy highly correlated with the 1st peak amplitude (r = 0.86). The proportion of two or more peaks varied from 76.8% to 87.9% by viscosity and volume. Further research is needed to examine the concurrent validity and generalizability of the ultrasonic Doppler sensor-based SMAS.

Analysis of natural finger-press motions for design of trackball buttons.

This study analysed natural press motions of the index, middle and ring fingers for ergonomic design of the positions and surface angles of the left, middle and right trackball buttons. Finger motions of 26 male participants for naturally pressing the trackball buttons were recorded after the participants adjusted the trackball buttons to their preferred locations for comfortable pressing. The natural positions of the finger pulps formed a symmetrically rainbow-shaped reach zone for the fingers. The natural press angles of the fingers' motion trajectories to the vertical reference line ranged from 14.2° to 20.5°, suggesting an 18-degree surface from the horizontal line for the trackball buttons. Regression formulas (adjusted R2 = 0.90 ± 0.07 and mean squared error = 8.55 ± 7.52 mm) were established to estimate the natural positions of finger pulps from hand segment lengths and joint angles for a population having different hand sizes from this study. Relevance to industry.

Development of an LCD-Based Visual Field System.

BACKGROUND: The present study investigated the diagnostic effectiveness of an LCD-based visual field testing system (LVF) in comparison with the standard automated perimetry Humphrey Field Analyzer II-750i (HFA). METHODS: A randomized controlled crossover study was conducted with 202 normal and 128 glaucomatous eyes using both LVF and HFA. The visual field testing systems were compared in terms of mean deviation (MD), pattern standard deviation (PSD), and area under the receiver operating characteristics curve (AUC) of MD and PSD differentiating the normal and glaucomatous eyes. RESULTS: Significant correlations were found between MD measurements from LVF and those from HFA for normal eyes (r = 0.342) and glaucomatous eyes (r = 0.796); slightly higher significant correlations were identified between PSD measurements from LVF and those from HFA for normal eyes (r = 0.363) and glaucomatous eyes (r = 0.828). Furthermore, high AUCs of MD were found as 0.786 for LVF and 0.868 for HFA and AUCs of PSD as 0.913 for LVF and 0.932 for HFA. CONCLUSION: The comparison results of the present study support the competence of LVF compared with HFA in visual field testing for early detection of glaucoma.

Anthropometric analysis of 3D ear scans of Koreans and Caucasians for ear product design.

The present study measured 25 dimensions of the ear including the concha and ear canal for ergonomic design of ear products and compared with existing ear measurement studies. Scanning and casting methods were employed to produce 3D ear images for 230 Koreans and 96 Caucasians and measurements of the ear dimensions were obtained by identifying 21 landmarks on individual ear scan image. The Korean ear measurements were found significantly larger (mean difference d¯ = 0.4-3.7 mm) and more varied (ratio of SDs =1.01-1.55) than those of Caucasians in most of ear dimensions. The average ear length and ear breadth of male were significantly longer ( d¯ = 1.3-7.0 mm) and wider ( d¯ = 0.8-3.0 mm) than those of female. Use of gender- and ethnicity-composite ear data is recommended in product design due to the much larger intra-population variations (7.5-22.2 mm) than the corresponding inter-population variations. Practitioner Summary: The 3D ear measurements of Koreans and Caucasians were collected and compared with those of different ethnic populations. The distinct ear features of the populations identified in this study are applicable to ergonomic design of ear products with better fit and comfort. Abbreviations: CCW: cavum concha width; CV: coefficient of variation; EB: ear breadth; EL: ear length; SD: standard deviation; SE: sampling error; 3D: 3 dimensional.

The Effects of Age, Gender, and Hand on Force Control Capabilities of Healthy Adults.

OBJECTIVE: The present study examined the effects of age (20s to 70s), gender (male and female), and hand (dominant and nondominant) on force control capabilities (FCCs) in four force control phases (initiation, development, maintenance, and termination). BACKGROUND: Normative data of FCCs by force control phase are needed for various populations in age and gender to identify a type of motor performance reduction and its severity. METHOD: FCCs of 360 participants (30 for each combination of age group and gender) were measured using a finger dynamometer and quantified in terms of initiation time (IT), development time (DT), maintenance error (ME), and termination time (TT). RESULTS: Although gradual increases (1%~28%) by age were shown in IT, DT, and TT, a dramatic increase in ME was observed among participants in their 50s (26%), 60s (68%), and 70s (160%) compared to those in their 20s~40s. The most distinctive interaction effect of age and gender was found in ME out of the four FCC measures. Lastly, hand and its related interactions were not found significant. CONCLUSION: Normative FCC data were established for four age groups (20s~40s, 50s, 60s, and 70s) and gender. APPLICATION: The normative FCC data can be used for evaluating an individual's motor performance, screening patients with brain disorders, and designing input devices triggered and/or operated by the finger.

Effects of a cognitive-enhancement group training program on daily living activities, cognition, and depression in the demented elderly.

[Purpose] The effects of a cognitive enhancement group training program on daily living activities, cognition, and depression in the demented elderly population of a local Korean community were investigated. [Subjects and Methods] The study included 22 elderly subjects who were 65 years of age or older, had been diagnosed with dementia, and were attending a daily care center in K City, Republic of Korea. Eleven subjects participated in the program, which was conducted twice a week for 8 weeks for a total of 16 sessions. Eleven subjects in a non-training group did not receive any interventions. [Results] The MMSE-K, MBI and KDS scores of all of the eleven subjects who participated in the program improved, and the improvements were statistically significant. [Conclusion] Cognitive enhancement group training programs may have positive effects on daily living activities, cognition, and depression.

Motor intentional disorders in vascular mild cognitive impairment and vascular dementia of subcortical type.

Subcortical vascular mild cognitive impairment (svMCI), a prodromal stage of subcortical vascular dementia (SVaD), is primarily associated with frontal injuries, whereas amnestic MCI (aMCI) is associated with temporoparietal injuries. Twenty-seven patients with svMCI, 20 with aMCI, 14 with SVaD, and 10 normal controls underwent motor intentional tasks (force initiation, development, maintenance, and termination) using a force dynamometer. Of the four motor intentional tasks, the maintenance task proved sensitive in differentiating svMCI from aMCI. In most motor intentional tasks, performances of svMCI patients were intermediate between those of controls and SVaD patients (initiation and termination: NC=aMCI=svMCI>SVaD; development: NC>aMCI=svMCI>SVaD; maintenance: NC=aMCI>svMCI=SVaD).

Development of Korean Representative Headforms for the Total Inward Leakage Testing on Filtering Facepiece Respirators.

Background: The lack of headforms that accurately reflect the head characteristics of Koreans and the demographic composition of the Korean population can lead to inadequate FFR testing and reduced effectiveness of FFRs. Method: Direct measurements of 5,110 individuals and 3D measurements of 2,044 individuals, aged between 9 and 69 years, were sampled from the data pool of Size Korea surveys based on the age and gender ratios of the Korean resident demographics. Seven head dimensions were selected based on the ISO 16976-2, availability of Size Korea measurements, and their relevance to the fit performance of FFRs. A principal component analysis (PCA) was performed using the direct measurements to extract the main factors explaining the head characteristics and then the main factors were standardized and remapped to 3D measurements, creating five size categories representing Korean head shapes. Lastly, representative 3D headforms were constructed by averaging five head shapes for each size category. Results: The study identified two main factors explaining Korean head characteristics by the PCA procedure specified in ISO 16976-2 and developed five representative headforms reflecting the anthropometric features of Korean heads: medium, small, large, short & wide, and long & narrow. Conclusion: This study developed representative headforms tailored to the Korean population for conducting total inward leakage (TIL) tests on filtering facepiece respirators (FFRs). The representative headforms can be used for TIL testing by employing robotic headforms to enhance the performance of FFRs for the Korean target population.

An anthropometric analysis of Korean male helicopter pilots for helicopter cockpit design.

This study measured 21 anthropometric dimensions (ADs) of 94 Korean male helicopter pilots in their 20s to 40s and compared them with corresponding measurements of Korean male civilians and the US Army male personnel. The ADs and the sample size of the anthropometric survey were determined by a four-step process: (1) selection of ADs related to helicopter cockpit design, (2) evaluation of the importance of each AD, (3) calculation of required sample sizes for selected precision levels and (4) determination of an appropriate sample size by considering both the AD importance evaluation results and the sample size requirements. The anthropometric comparison reveals that the Korean helicopter pilots are larger (ratio of means = 1.01-1.08) and less dispersed (ratio of standard deviations = 0.71-0.93) than the Korean male civilians and that they are shorter in stature (0.99), have shorter upper limbs (0.89-0.96) and lower limbs (0.93-0.97), but are taller on sitting height, sitting eye height and acromial height (1.01-1.03), and less dispersed (0.68-0.97) than the US Army personnel. PRACTITIONER SUMMARY: The anthropometric characteristics of Korean male helicopter pilots were compared with those of Korean male civilians and US Army male personnel. The sample size determination process and the anthropometric comparison results presented in this study are useful to design an anthropometric survey and a helicopter cockpit layout, respectively.

Analysis of the facial measurements of Korean Air Force pilots for oxygen mask design.

This study measured the facial dimensions of Korean Air Force (KAF) pilots, to design a pilot oxygen mask, and compared them with those of Korean civilians and US Air Force (USAF) personnel. Twenty-two facial dimensions were measured for 278 KAF male pilots (KMP) and 58 KAF female pilots and cadets (KFP) using an anthropometer and a three-dimensional scanner. The KMP face measurements were found to be significantly larger (mean difference, [Formula: see text] = 0.7-26.5 mm) and less varied (ratio of SDs = 0.29-0.82) than those of Korean male civilians. The average face length, lip width and nasal root breadth of the KMP were significantly longer ([Formula: see text] = 4.7 mm), narrower ([Formula: see text] = -2.4 mm), and wider ([Formula: see text] = 5.2 mm), respectively, than those of USAF male personnel. Lastly, the KMP face measurements were significantly larger ([Formula: see text] = 1.8-26.1 mm) than those of the KFP. PRACTITIONER SUMMARY: The face measurements of KAF pilots were collected and compared with those of Korean civilians and USAF personnel. The distinct facial features of the populations identified in this study are applicable to custom design of an oxygen mask for prevention of excessive pressure and oxygen leakage.

Quantitative Analysis of the Head Tilt Using Three-Dimensional Temporal Scan in Children with Torticollis.

The head tilt of patients with torticollis is usually evaluated subjectively in clinical practice and measuring it in young children is very limited due to poor cooperation. No study has yet evaluated the head tilt using a three-dimensional (3D) scan and compared it with other measurement methods. Therefore, this study aimed to objectively demonstrate head tilt through clinical measurements and a 3D scan in children with torticollis. A total of 52 children (30 males, 22 females; age 4.6 ± 3.2 years) diagnosed with torticollis and 52 adults (26 men, 26 women; age 34.42 ± 10.4 years) without torticollis participated in this study. The clinical measurements were performed using a goniometer and still photography methods. Additionally, the head tilt was analyzed using a 3D scanner (3dMD scan, 3dMD Inc., Atlanta, GA, USA). There was a high correlation between the other methods and 3D angles, and the cut-off value of the 3D angles for the diagnosis of torticollis was also presented. The area under the curve of the 3D angle was 0.872, which was confirmed by a moderately accurate test and showed a strong correlation compared with other conventional tests. Therefore, we suggest that measuring the degree of torticollis three-dimensionally is significant.

Effect of Voice and Articulation Parameters of a Home-Based Serious Game for Speech Therapy in Children With Articulation Disorder: Prospective Single-Arm Clinical Trial.

BACKGROUND: Articulation disorder decreases the clarity of language and causes a decrease in children's learning and social ability. The demand for non-face-to-face treatment is increasing owing to the limited number of therapists and geographical or economic constraints. Non-face-to-face speech therapy programs using serious games have been proposed as an alternative. OBJECTIVE: The aim of this study is to investigate the efficacy of home therapy on logopedic and phoniatric abilities in children with articulation disorder using the Smart Speech game interface. METHODS: This study is a prospective single-arm clinical trial. Children with articulation disorders, whose Urimal Test of Articulation and Phonology (U-TAP) was -2 SDs or less and the Receptive and Expressive Vocabulary Test score was -1 SD or more, were enrolled. A preliminary evaluation (E0) was conducted to check whether the children had articulation disorders, and for the next 4 weeks, they lived their usual lifestyle without other treatments. Prior to the beginning of the training, a pre-evaluation (E1) was performed, and the children trained at home for ≥30 minutes per day, ≥5 times a week, over 4 weeks (a total of 20 sessions). The Smart Speech program comprised oral exercise training, breathing training, and speech training; the difficulty and type of the training were configured differently according to the participants' articulation error, exercise, and vocal ability. After the training, postevaluation (E2) was performed using the same method. Finally, 8 weeks later, postevaluation (E3) was performed as a follow-up. A voice evaluation included parameters such as maximum phonation time (MPT), fundamental frequency (F0), jitter, peak air pressure (relative average perturbation), pitch, intensity, and voice onset time. Articulation parameters included a percentage of correct consonants (PCC; U-TAP word-unit PCC, U-TAP sentence-unit PCC, and three-position articulation test) and alternate motion evaluation (diadochokinesis, DDK). Data obtained during each evaluation (E1-E2-E3) were compared. RESULTS: A total of 13 children with articulation disorders aged 4-10 years were enrolled in the study. In voice parameters, MPT, jitter, and pitch showed significant changes in repeated-measures ANOVA. However, only MPT showed significant changes during E1-E2 (P=.007) and E1-E3 (P=.004) in post hoc tests. Other voice parameters did not show significant changes. In articulation parameters, U-TAP, three-position articulation test (TA), and DDK showed significant changes in repeated-measures ANOVA. In post hoc tests, U-TAP (word, sentence) and TA showed significant changes during E1-E2 (P=.003, .04, and .01) and E1-E3 (P=.001, .03, and .003), and DDK showed significant changes during E1-E2 only (P=.03). CONCLUSIONS: Home-based serious games can be considered an alternative treatment method to improve language function. TRIAL REGISTRATION: Clinical Research Information Service KCT0006448; https://cris.nih.go.kr/cris/search/detailSearch.do/20119.

An Open-Source Real-Time Motion Correction Plug-In for Single-Photon Calcium Imaging of Head-Mounted Microscopy.

Single-photon-based head-mounted microscopy is widely used to record the brain activities of freely-moving animals. However, during data acquisition, the free movement of animals will cause shaking in the field of view, which deteriorates subsequent neural signal analyses. Existing motion correction methods applied to calcium imaging data either focus on offline analyses or lack sufficient accuracy in real-time processing for single-photon data. In this study, we proposed an open-source real-time motion correction (RTMC) plug-in for single-photon calcium imaging data acquisition. The RTMC plug-in is a real-time subpixel registration algorithm that can run GPUs in UCLA Miniscope data acquisition software. When used with the UCLA Miniscope, the RTMC algorithm satisfies real-time processing requirements in terms of speed, memory, and accuracy. We tested the RTMC algorithm by extending a manual neuron labeling function to extract calcium signals in a real experimental setting. The results demonstrated that the neural calcium dynamics and calcium events can be restored with high accuracy from the calcium data that were collected by the UCLA Miniscope system embedded with our RTMC plug-in. Our method could become an essential component in brain science research, where real-time brain activity is needed for closed-loop experiments.

Calcium Activation of Parvalbumin Neurons Induced by Electrical Motor Cortex Stimulation.

Electrical motor cortex stimulation (EMCS) has been used for Parkinson's Disease (PD) treatment. Some studies found that distinct cell types might lead to selective effects. As the largest subgroup of interneurons, Parvalbumin (PV) neurons have been reported to be involved in the mechanisms of therapeutic efficacy for PD treatment. However, little is known about their responses to the EMCS. In this study, we used in-vivo two-photon imaging to record calcium activities of PV neurons (specific type) and all neurons (non-specific type) in layer 2/3 primary motor cortex (MI) during EMCS with various stimulus parameters. We found PV neurons displayed different profiles of activation property compared to all neurons. The cathodal polarity preference of PV neurons decreased at a high-frequency stimulus. The calcium transients of PV neurons generated by EMCS trended to be with large amplitude and short active duration. The optimal activation frequency of PV neurons is higher than that of all neurons. These results improved our understanding of the selective effects of EMCS on specific cell types, which could bring more effective stimulation protocols for PD treatment.

Ergonomics and Personalization of Noninvasive Ventilation Masks.

Although noninvasive ventilation (NIV) is administered to manage respiratory failure due to various causes, safety and effectiveness issues associated with the use of NIV masks have been reported. The present article aims to provide health professionals with a comprehensive review of the ergonomic considerations of NIV masks in terms of design, evaluation, and personalization. Based on a review of 93 papers, we provide guidelines for mask selection and troubleshooting during mask use as well as ergonomic approaches including face anthropometry, sizing systems, mask design, evaluation, and personalization. The comprehensive information presented in this review provides ergonomic perspectives to identify and prevent safety and usability problems associated with the use of NIV masks. Ergonomic improvement and personalization are important goals in order to facilitate the success of NIV treatment.

Development of an ergonomic design process for smartphone hard key locations.

Smartphone hard key locations need to be ergonomically determined to improve grip stability and operational efficiency for users' convenience. The present study proposed an ergonomic design process that determines smartphone hard key locations by statistically analyzing the preferred hard key control areas of users with various hand sizes based on users' preferred grip postures and hard key control areas. The proposed design process analyzes the characteristics of product design, user, task, and use context, the types of preferred grip posture, the preference distribution of grip posture, and the preference distribution of hard-key area, and then recommends the locations of hard keys by considering the preference distribution of hard-key area and design constraints. The proposed design process was applied to a smartphone with a 5-inch screen, resulting in 77-96 mm from the bottom of the device for a volume key to 20 mm on the left side and 88-97 mm for a power key to 10 mm on the right side. The proposed design process for the determination of smartphone hard-key locations would be of use to determine the locations of various portable product interfaces.

Online Decoding System with Calcium Image From Mice Primary Motor Cortex.

With the development of calcium imaging, neuroscientists have been able to study neural activity with a higher spatial resolution. However, the real-time processing of calcium imaging is still a big challenge for future experiments and applications. Most neuroscientists have to process their imaging data offline due to the time-consuming of most existing calcium imaging analysis methods. We proposed a novel online neural signal processing framework for calcium imaging and established an Optical Brain-Computer Interface System (OBCIs) for decoding neural signals in real-time. We tested and evaluated this system by classifying the calcium signals obtained from the primary motor cortex of mice when the mice were performing a lever-pressing task. The performance of our online system could achieve above 80% in the average decoding accuracy. Our preliminary results show that the online neural processing framework could be applied to future closed-loop OBCIs studies.