Effect of a Multiple Reduction Die on the Residual Stress of Drawn Materials.

Residual stress may influence the mechanical behavior and durability of drawn materials. Thus, this study develops a multiple reduction die (MRD) that can reduce residual stress during the drawing process. The MRD set consists of several die tips, die cases, and lubricating equipment. All the die tips of the MRD were disposed of simultaneously. Finite element analysis of the drawing process was performed according to the reduction ratio of each die tip, and the variables in drawing process with the MRD were optimized using a deep neural network to minimize the residual stress. Experiments on the drawing process with the conventional die and MRD were performed to evaluate the residual stress and verify the effectiveness of the MRD. The results of X-ray diffraction measurements indicated that the axial and hoop residual stresses on the surface were dramatically reduced.

Multi-Stage Cold Forging Process for Manufacturing a High-Strength One-Body Input Shaft.

A multi-stage cold forging process was developed and complemented with finite element analysis (FEA) to manufacture a high-strength one-body input shaft with a long length body and no separate parts. FEA showed that the one-body input shaft was manufactured without any defects or fractures. Experiments, such as tensile, hardness, torsion, and fatigue tests, and microstructural characterization, were performed to compare the properties of the input shaft produced by the proposed method with those produced using the machining process. The ultimate tensile strength showed a 50% increase and the torque showed a 100 Nm increase, confirming that the input shaft manufactured using the proposed process is superior to that processed using the machining process. Thus, this study provides a proof-of-concept for the design and development of a multi-stage cold forging process to manufacture a one-body input shaft with improved mechanical properties and material recovery rate.

Study on Effect of Shapes of Serration of Joining Plane on Joining Characteristics for the Aluminum-Steel Multi-Materials Press Joining Process.

Recently, mechanical joining processes have received much attention for joining multi-materials. In particular, these processes have a great demand in the automobile industry for weight reduction. The press-fitting process is a representative mechanical joining process. In this process, the shape of the interfacial serration on the joining plane is very important because it has a significant effect on the joining strength. In this study, the characteristics of the aluminum-steel press joining process were investigated according to the shape of the interfacial serration of the joining plane. The deformation of the material and the forming load were investigated by conducting finite element analysis. In addition, the unfilled height of the material, joining force, and torque were measured experimentally.

Prediction of Effective Strain Distribution in Two-Pass Drawn Wire.

In the multi-pass wire drawing process, the diameter of a wire is decreased by continuously passing it through progressively smaller drawing dies. Although the deformation depends on the process variables, in most wire drawing processes, the wire deformation is concentrated on the surface by its direct contact with the drawing dies, causing a nonlinear distribution of radial direction effective strain from the center to the surface. In this study, a new model for predicting this effective strain in two-pass drawn wire was derived based on the upper bound method, and a finite element analysis and drawing experiment were conducted to validate its effectiveness. The proposed model offers a promising approach to determining and thus controlling the strain in multi-pass drawn wire.

Development and validation of a symptom assessment tool for postmicturition dribble: A prospective, multicenter, observational study in Korea.

OBJECTIVES: Postmicturition dribble (PMD) is a very common symptom in males with lower urinary tract symptoms (LUTS) worldwide, but there is no adequate questionnaire to assess it. Therefore, we developed a questionnaire named the Hallym Post Micturition Dribble Questionnaire (HPMDQ) to assess PMD, and the aim of this study is to validate it. METHODS: A series of consecutive male patients newly diagnosed with LUTS and over 40 years of age who visited any of 5 medical institutions were included. LUTS were assessed in all patients using the International Prostate Symptom Score (IPSS), and PMD was assessed using the HPMDQ. RESULTS: In total, 2134 male patients aged 40 to 91 years were included in this study. Of these patients, 1088 (51.0%) reported PMD. In the PMD group, the mean values for HPMDQ-Q1, HPMDQ-Q2, HPMDQ-Q3 and HPMDQ total score were 1.39, 1.10, 1.76 and 4.25, respectively. In the non-PMD group, the mean values of these scores were 0, 0.18, 1.52 and 1.58, respectively. The difference in HPMDQ scores between the 2 groups was statistically significant. PMD was significantly associated with the voiding symptoms of LUTS, prostate size and postvoid residual but not with storage symptoms. CONCLUSIONS: The HPMDQ, which consists of 5 questions (frequency, severity, bother, quality of life and response to treatment for PMD), was developed, and its use for assessing PMD is validated in this study. It may be a useful tool for further research and in clinical practice for PMD.

Fabrication of 50.0 µm Ultra-Fine Pure Rhodium Wire, Using a Multi-Pass Wire Drawing Process, for Probe Card Pins.

Rhodium is a rare material that is widely used in electrical and electronic components due to its excellent mechanical and electrical properties. Ultra-fine rhodium wires in particular are widely used in electronic components. In this study, a multi-pass wire drawing process was designed to fabricate ultra-fine pure rhodium wire with a diameter of 50.0 µm from an initial diameter of 80.0 µm, which is used as probe card pins. An elastic-plastic finite element (FE) analysis was performed to validate the pass schedule that was designed for this study. A fine wire drawing experiment was also carried out to verify the effectiveness of the designed process. As a result, the ultra-fine rhodium wire was fabricated using the design process without wire breaks and the diameter of the final drawn wire was 47.80 µm.

Effect of tadalafil 5 mg on post-micturition dribble in men with lower urinary tract symptoms: a multicentre, double-blind, randomized, placebo-controlled trial.

OBJECTIVES: To compare the effects of taking tadalafil 5 mg and placebo once daily on post-micturition dribble (PMD) in men with lower urinary tract symptoms (LUTS). PATIENTS AND METHODS: Our prospective, randomized, double-blind, placebo-controlled, multicentre trial enrolled 102 men with PMD and other LUTS. PMD was assessed using the Hallym Post-Micturition Dribble Questionnaire (HPMDQ) and according to PMD volume. Over a 12-week period, patients took either tadalafil 5 mg (n = 51) or placebo (n = 51) once daily and their HPMDQ and PMD volume results were evaluated. Adverse events (AEs) were also reported. RESULTS: Over the course of 12 weeks, total HPMDQscores and PMD volumes improved significantly more in the tadalafil group than in the placebo group (reduction of total HPMDQ score of ≥2 points in the tadalafil and placebo group in 68.8% and 31.9% of patients (P < 0.001) and decreased mean PMD volume in the tadalafil and placebo group at 0.48 mL and 0.22  mL, respectively (P = 0.046). Specifically, PMD frequency decreased and quality of life increased significantly more in the tadalafil group than in the placebo group (P = 0.029 and P < 0.001, respectively). Furthermore, 66.7% of the tadalafil group reported moderate and significant PMD improvement, whereas only 4.2% reported that tadalafil was ineffective. Treatment-emergent AEs did not significantly differ between the groups (all P > 0.05), and no serious AEs were observed. CONCLUSION: Taking tadalafil 5 mg once daily reduced PMD symptom severity and PMD volume in men with PMD, without inducing serious AEs, more effectively than placebo, suggesting that taking tadalafil 5 mg once daily may be an effective and well-tolerated PMD treatment.

Development of a Multi-Pass Drawing Process Design System for Steel Profiles.

The process design of a multi-pass steel profile drawing depends mainly on the experience of the industrial experts. Therefore, in the actual industrial field, a systematic design method is required to improve the efficiency of process design. Development of such a method will result in a reduction in production cost and time. In this study, a process design system that can be installed in AutoCAD V14 was developed. By using the developed design system, the drawing load, stress, and strain, among other parameters, can be calculated. In addition, intermediate die shapes can be designed. After the process design, both process information and drawings of dies can be obtained. In order to verify the effectiveness of the developed process design system, it was used to design multi-pass profile drawing processes. Finally, finite element (FE) analysis and a drawing experiment were carried out to verify the designed processes.

The effect of 20-week continuous 60 Hz magnetic field exposure on testicular function in sprague-dawley rats.

Accumulating evidence does not yet confirm the effect of power line frequency magnetic field (MF) on human health and fertility. We recently reported that, at continuous 60 Hz MF exposure in mice, the dose given as magnetic flux density (tesla; T) and duration of exposure was related to induce testicular germ cell apoptosis. We aimed to characterize the effect of a 20-week continuous exposure to 60 Hz MF on the motility, morphology, and number of sperm as well as the apoptosis of testicular germ cell in rats. Sprague-Dawley rats were exposed for 20 weeks to 60 Hz MF of 2, 20, or 200 µT for 24 h/day with rats exposed to sham conditions, serving as the control. The exposure to 60 Hz MF of 2 and 20 µT had no effects on testicular in this study. The exposure to 60 Hz MF of 200 µT for 20 weeks induced increases of the apoptotic cells (P < 0.001) in germ cells and decreases of sperm numbers (P < 0.05). However, the MF did not significantly affect the body or testis mass, seminiferous tubule diameter, or the motility or morphology of sperm. This study concluded that exposure to 60 Hz MF of 200 µT can increase testicular germ cell apoptosis, especially spermatogonia, and reduce sperm count. Also compared to previous mice studies, rats are less sensitive than mice to exposure to 60 Hz MF. Bioelectromagnetics. 39:539-546, 2018. © 2018 Wiley Periodicals, Inc.

Postmicturition Dribble Is Associated with Erectile Dysfunction in Middle-Aged and Older Men with Lower Urinary Tract Symptoms.

PURPOSE: Lower urinary tract symptoms (LUTS) are correlated with erectile dysfunction (ED), but research on whether postmicturition dribble (PMD) is related to ED is limited. We assessed the correlation between PMD and ED in middle-aged and older Korean men with LUTS. MATERIALS AND METHODS: In our prospective, cross-sectional, observational, multicenter study, we enrolled 205 men (age >40 years) with LUTS. LUTS and ED were assessed using the International Prostate Symptom Score (IPSS) and International Index of Erectile Function-5 (IIEF-5), respectively. PMD was assessed using the Hallym PostMicturition Dribble Questionnaire, Question 1, and the PMD volume was calculated in a paper test. Age, prostate volume, serum prostate-specific antigen, maximum urinary flow rate, and postvoid residual urine were also evaluated. RESULTS: There were significant differences in the total and voiding IPSS between men with and without ED (p=0.042 and 0.043, respectively). The Hallym PostMicturition Dribble Questionnaire 1 score was inversely well correlated with the IIEF-5 score (r=-0.388, p<0.001). Also, the PMD volume was inversely correlated with the IIEF-5 score (r=-0.138, p=0.042). ED prevalence increased as the Hallym PostMicturition Dribble Questionnaire 1 score increased (p=0.002). Further, incorporating the Hallym PostMicturition Dribble Questionnaire 1 into the IPSS tended to increase the predictive accuracy of LUTS by 4.2% in ED patients (p=0.082). CONCLUSIONS: PMD was significantly correlated with ED and reinforced the relationship between LUTS and ED in middle-aged and older men. PMD might be an important component of the association between LUTS and ED.

Medical Resource Consumption and Quality of Life in Peripheral Arterial Disease in Korea: PAD Outcomes (PADO) Research.

BACKGROUND AND OBJECTIVES: We aimed to investigate the history of medical resource consumption and quality of life (QoL) in peripheral arterial disease (PAD) patients in Korea. METHODS: This was a prospective, multi-center (23 tertiary-hospitals, division of cardiology), non-interventional study. Adult patients (age ≥20 years) suffering from PAD for the last 12-month were enrolled in the study if they met with any of following; 1) ankle-brachial index (ABI) ≤0.9, 2) lower-extremity artery stenosis on computed tomography angiography ≥50%, or 3) peak-systolic-velocity-ratio (PSVR) on ultrasound ≥2.0. Medical chart review was used to assess patient characteristics/treatment patterns while the history of medical resource consumption and QoL data were collected using a patient survey. QoL was measured using EuroQoL-5-dimensions-3-level (EQ-5D-3L) score system, and the factors associated with QoL were analyzed using multiple linear regression analysis. RESULTS: This study included 1,260 patients (age: 69.8 years, male: 77.0%). The most prevalent comorbidities were hypertension (74.8%), hyperlipidemia (51.0%) and diabetes-mellitus (50.2%). The 94.1% of the patients took pharmacotherapy including aspirin (76.2%), clopidogrel (53.3%), and cilostazol (33.6%). The 12.6% of the patients were receiving smoking cessation education/pharmacotherapy. A considerable number of patients (500 patients, 40.0%) had visit history to another hospital before diagnosis/treatment at the current hospital, with visits to orthopedic units (50.4%) being the most common. At the time, 29% (or higher) of the patients were already experiencing symptoms of critical limb ischemia. Baseline EQ-5D index and EQ VAS were 0.64±0.24 and 67.49±18.29. Factors significantly associated with QoL were pharmacotherapy (B=0.05053; p=0.044) compared to no pharmacotherapy, and Fontaine stage improvement/maintain stage I (B=0.04448; p<0.001) compared to deterioration/maintain stage II-IV. CONCLUSIONS: Increase in disease awareness for earlier diagnosis and provision of adequate pharmacotherapy is essential to reduce disease burden and improve QoL of Korean PAD patients.

Author Correction to: The transgluteal approach to shockwave lithotripsy to treat distal ureter stones: a prospective, randomized, and multicenter study.

The funding number was incorrect in the original published article. The correct funding number should read as follows.

The transgluteal approach to shockwave lithotripsy to treat distal ureter stones: a prospective, randomized, and multicenter study.

PURPOSE: We compared the outcomes of SWL to treat distal ureter stones with regard to the conventional prone and supine positions using the transgluteal approach through the greater sciatic foramen. METHODS: A prospective, randomized, single-blind, and multicenter study was conducted between October 2014 and July 2015. The inclusion criteria were radio-opaque distal ureter stones with a maximum diameter of 0.5-2 cm as measured on a CT scan. The included 160 patients were randomly assigned to two groups: the prone group (n = 80; treated in the conventional prone position) and the transgluteal group (n = 80; treated in the supine position using a transgluteal approach). In the latter group, the focused shock wave was transmitted through the greater sciatic foramen with the head positioned at a 40° angle to the vertical. "Stone-free" was defined as the complete clearance of stone fragments, assessed using a CT scan at 2 weeks after treatment. Overall satisfaction was self-reported using a 0-5 Likert scale. RESULTS: The overall efficacy was 66.9%. The stone-free rate was significantly higher in the transgluteal group (72.6%) than in the prone group (54.7%; odds ratio 2.413, 95% CI 1.010-5.761, P = 0.023). No serious adverse events due to treatment were observed in either group. The satisfaction score of the transgluteal group was 4.21 ± 0.81, and 83.6% were willing to repeat the same procedure if necessary. CONCLUSIONS: SWL using the transgluteal approach via a supine position through the greater sciatic foramen was more effective than via the conventional prone position. Furthermore, this approach provided a comparably safe and satisfactory procedure.

Comparison of Fixed-dose Combinations of Amlodipine/Losartan Potassium/Chlorthalidone and Amlodipine/Losartan Potassium in Patients With Stage 2 Hypertension Inadequately Controlled With Amlodipine/Losartan Potassium: A Randomized, Double-blind, Multicenter, Phase III Study.

PURPOSE: The goal of this study was to compare the efficacy and safety of fixed-dose combinations of amlodipine/losartan potassium/chlorthalidone (A/L/C) and A/L in Korean patients with stage 2 hypertension inadequately controlled by A/L. METHODS: This study was an 8-week, randomized double-blind, multicenter, phase III clinical trial. Three hundred forty volunteer patients with stage 2 hypertension were randomized to receive A/L/C or A/L. The primary end point was a change in sitting systolic blood pressure (SitSBP) after 8 weeks of treatment. As secondary end points, the change in SitSBP after 2 weeks of treatment and the change in sitting diastolic blood pressure (SitDBP) were compared between treatment groups. All patients were assessed for adverse events, clinical laboratory data, and vital signs. FINDINGS: Of 330 patients from 33 medical centers, 328 patients who had available efficacy data were analyzed. After 8 weeks of double-blind treatment, the mean (SD) changes in SitSBP at 8 weeks were -16.4 (0.9) mm Hg and -6.9 (1.0) mm Hg in the A/L/C and A/L groups, respectively. A/L/C had a statistically superior blood pressure-lowering effect compared with that of A/L (mean [SD] difference, 9.5 [1.3] mm Hg; P < 0.001). The mean (SD) change in SitDBP at 8 weeks was significantly greater with A/L/C (-8.0 [0.6] mm Hg) than with A/L (-3.6 [0.6] mm Hg) (P < .001). In terms of the mean (SD) change in SitDBP at 2 weeks compared with baseline, A/L/C (-5.9 [0.5] mm Hg) was statistically different from A/L (-2.9 [0.5] mm Hg) (P < .001). Mean (SD) SitSBP change from baseline to week 2 was -13.2 (0.9) and -5.5 (0.9) in the A/L/C and A/L groups, respectively, with a statistically significant blood pressure-lowering effect (P < 0.001). The number of participants who achieved target blood pressure at week 8 was significantly higher in the A/L/C group (93 patients [55.7%]) than in the A/L group (48 [29.8%]) (P < 0.001). Adverse drug reactions were observed in 23 patients (7.0%), and the incidence of dizziness was significantly higher in the A/L/C group than in the A/L group (4.8% vs 0.6%, P = 0.037) There were no serious adverse events associated with the study drugs. IMPLICATIONS: The results of this study suggest that A/L/C had a significantly increased blood pressure-lowering efficacy compared with that of A/L and had a good safety profile. ClinicalTrials.gov identifier: NCT02916602.

Alcohol, Smoking, Physical Activity, Protein, and Lower Urinary Tract Symptoms: Prospective Longitudinal Cohort.

PURPOSE: To evaluate risk factors for deterioration of lower urinary tract symptoms (LUTS) in elderly men in a community-based, prospective longitudinal cohort study. METHODS: In a suburban area in Korea, 1,514 subjects aged ≥45 years were randomly selected by systematic sampling. A total of 918 elderly subjects were enrolled in this in-depth clinical study in 2004. Of these, 547 participants were followed up for 3 years and the data was analyzed in 2014. Standard questionnaires were administered face-to-face by trained interviewers. After excluding women, 224 male participants with complete data including transrectal ultrasonography were included in the final analysis. LUTS were diagnosed using the International Prostate Symptom Score (IPSS) questionnaire. Symptom deterioration was defined as a score of ≥8 points during the 3-year follow-up period. RESULTS: LUTS prevalence increased to 13.1% and the mean IPSS increased by 2.6 points during the 3-year period. After adjusting for confounders, a smoking history of ≥50 pack-years was an independent risk factor for deterioration of LUTS and storage subsymptoms compared with no history of smoking (3.1 and 5.1 odds, respectively). Physical activity had a protective effect on voiding subsymptoms. However, high protein diet and alcohol intake were not associated with LUTS deterioration. CONCLUSIONS: The LUTS prevalence among elderly men living in a suburban area increased to 13.1% and the IPSS increased by 2.6 points during the 3-year period. A history of heavy smoking, low physical activity, and high protein intake were associated with LUTS deterioration. However, there was no significant association between alcohol intake and LUTS deterioration.

Relationship between Metabolic Syndrome and Lower Urinary Tract Symptoms: Hallym Aging Study.

The aim of the study was to test the hypothesis that the metabolic syndrome (MS) is linked to lower urinary tract symptoms (LUTS) in Korean men. This was a longitudinal study that used data collected from 328 men aged 50-89 years who were randomly selected among 1,520 participants in 2004. We collected information from 224 (68.3%) men among the original responders on the biological, medical, psychological, social, lifestyle, and economic factors in 2007. The prevalence of the MS was 187/328 (57.0%) in 2004 and 125/224 (55.8%) in 2007 among men, respectively. There was no significantly greater increase in the IPSS in men with the MS than in men without the MS over a 3-year period of time (2.0 ± 9.37 versus 3.0 ± 8.44, p = 0.402, resp.). In the multivariate logistic regression analysis with control for age and life style factors, the risk factors for moderate/severe LUTS were age and erectile dysfunction (p < 0.05). However, the presence of the MS did not increase the risk of moderate/severe LUTS (OR = 1.09, 95% CI 0.63-1.89, p = 0.748). Our cross-sectional and longitudinal risk factor analyses do not support the hypothesis that the MS is linked to LUTS in Korean men.

Can estimated intravaginal ejaculatory latency time be used interchangeably with stopwatch-measured intravaginal ejaculatory latency time for the diagnosis of lifelong premature ejaculation?

OBJECTIVE: To examine the correlation between estimated intravaginal ejaculatory latency time (eIELT) and stopwatch-measured intravaginal ejaculatory latency time (sIELT), and to assess the clinical utility of eIELT in identifying men more likely to have lifelong premature ejaculation (PE). METHODS: A prospective, observational, multicenter study was conducted. Between July 2010 and August 2011, 118 healthy men aged 30-70 years, more likely to have lifelong PE, were recruited from 5 institutions in Korea. All patients underwent preliminary assessments including collection of medical and sexual history, physical examination, determination of eIELT, and the Premature Ejaculation Profile questionnaire. During the 1-week study period, patients were requested to engage in sexual intercourse at least twice and to record the sIELT. RESULTS: eIELT and sIELT correlated well (r = 0.512; P < .001). However, eIELT was overestimated by a mean of 1.2 ± 0.2 minutes (median, 1.0 minutes) compared with sIELT (P = .046). eIELT showed a reduced correlation with the Premature Ejaculation Profile measures, compared with sIELT (each P-value < .05). The diagnostic accuracy of eIELT was 67.9% (P = .001), and an eIELT of 2 minutes was the acceptable cutoff value to diagnose lifelong PE. CONCLUSION: Although eIELT correlated well with sIELT, it was overestimated by approximately 1 minute and had lower clinical utility than sIELT. Our study suggests that eIELT and sIELT cannot be directly interchanged and that caution should be used when substituting sIELT with eIELT to identify men who are more likely to have lifelong PE.

A novel mathematical model to predict the severity of postoperative functional reduction before partial nephrectomy: the importance of calculating resected and ischemic volume.

PURPOSE: Preoperatively predicting postoperative kidney function is an essential step to achieve improved renal function and prevent chronic kidney disease. We introduce a novel formula especially to calculate resected and ischemic volume before partial nephrectomy. We examined whether resected and ischemic volume would have value for predicting postoperative renal function. MATERIALS AND METHODS: We performed a retrospective cohort study in 210 patients who underwent robotic partial nephrectomy between September 2006 and October 2013 at a tertiary cancer care center. Based on abdominopelvic computerized tomography and magnetic resonance imaging we calculated resected and ischemic volume by the novel mathematical formula using integral calculus. We comparatively analyzed resected and ischemic volume, and current nephrometry systems to determine the degree of association and predictability regarding the severity of the postoperative functional reduction. RESULTS: On multivariable analysis resected and ischemic volume showed a superior association with the absolute change in estimated glomerular filtration rate/percent change in estimated glomerular filtration rate (B = 6.5, p = 0.005/B = 6.35, p = 0.009). The ROC AUC revealed accurate predictability of resected and ischemic volume on the stratified event of an absolute change in estimated glomerular filtration rate/event of percent change in estimated glomerular filtration rate compared to 3 representative nephrometry systems. The calibration plot of this model was excellent (close to the 45-degree line) within the whole range of predicted probabilities. CONCLUSIONS: We report a method of preoperatively calculating resected and ischemic volume with a novel formula. This method has superior correlation with the absolute and percent change in estimated glomerular filtration rate compared to current nephrometry systems. The predictive model achieved a strong correlation for the absolute and percent change in estimated glomerular filtration rate.

Extremely low frequency magnetic fields induce spermatogenic germ cell apoptosis: possible mechanism.

The energy generated by an extremely low frequency electromagnetic field (ELF-EMF) is too weak to directly induce genotoxicity. However, it is reported that an extremely low frequency magnetic field (ELF-MF) is related to DNA strand breakage and apoptosis. The testes that conduct spermatogenesis through a dynamic cellular process involving meiosis and mitosis seem vulnerable to external stress such as heat, MF exposure, and chemical or physical agents. Nevertheless the results regarding adverse effects of ELF-EMF on human or animal reproductive functions are inconclusive. According to the guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP; 2010) for limiting exposure to time-varying MF (1 Hz to 100 kHz), overall conclusion of epidemiologic studies has not consistently shown an association between human adverse reproductive outcomes and maternal or paternal exposure to low frequency fields. In animal studies there is no compelling evidence of causal relationship between prenatal development and ELF-MF exposure. However there is increasing evidence that EL-EMF exposure is involved with germ cell apoptosis in testes. Biophysical mechanism by which ELF-MF induces germ cell apoptosis has not been established. This review proposes the possible mechanism of germ cell apoptosis in testes induced by ELF-MF.

Continuous exposure to 60 Hz magnetic fields induces duration- and dose-dependent apoptosis of testicular germ cells.

To evaluate duration- and dose-dependent effects of continuous exposure to a 60 Hz magnetic field (MF) on the testes in mice, BALB/c male mice were exposed to a 60 Hz MF at 100 µT for 24 h a day for 2, 4, 6, or 8 weeks, and at 2, 20, or 200 µT for 24 h a day for 8 weeks. Any exposures to MF did not significantly affect body or testicular masses. However, the apoptotic cells among testicular germ cells were increased duration-dependent at exposures of 100 µT for 6 and 8 weeks and dose-dependent at exposures of 20 and 200 µT for 8 weeks. The number of sperm in epididymis and the diameter of seminiferous tubule decreased in mice exposed to 100 and 200 µT for 8 weeks, respectively. To induce the apoptosis of testicular germ cell in mice, the minimum dose is 20 µT at continuous exposure to a 60 Hz MF for 8 weeks and the minimum duration is 6 weeks at continuous exposure of 100 µT. Taken together, these results suggest that continuous exposure to a 60 Hz MF might affect, duration- and dose-dependent biological processes including apoptotic cell death and spermatogenesis in the male reproductive system of mice.