• Journal of Korean Institute of Industrial Engineers
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• v.36 no.4
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• pp.212-218
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• 2010

This paper shows accuracy comparison results of reliability estimation methods for one-shot systems with respect to sample sizes. To compare accuracy in reliability estimation methods, quantal-response data, characterizing one-shot systems, were simulated using failure times of LED obtained through the accelerated life test, and then the true reliability over time was evaluated using the failure times. The simulated quantal-response data were used to estimate the true reliability through applying reliability estimation methods in open literature. Accuracy of each reliability estimation method was compared in terms of both SSE (Sum of Squared Error) and MSE (Mean Squared Error), and then estimation trend for each method is found. Feasible bounds which true reliability would exist within were estimated through applying the found trends to quantal-response data set of a real weapon system.

• Journal of Applied Reliability
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• v.18 no.3
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• pp.193-200
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• 2018

Purpose: In this study, the life of the motor is investigated by performing the accelerated life test with the brush wear of the industrial cleaner motor as the main failure mode. Methods: The accelerating stress factor of the accelerated life test is a voltage, which can increase the number of revolutions of the motor to accelerate the brush wear due to the friction between the brush and the commutator. Also, the accelerating stress level was determined after determining the maximum allowable level of the voltage through the preliminary test. Results: The motor failure time at each accelerating stress level was predicted by regression analysis with brush wear length as performance degradation data. The main failure mode, which is brush wear, of the motor was reproduced by this test. The shape parameter of the Weibull distribution was confirmed to be the same statistically at all accelerating stress levels by the likelihood ratio test. Conclusion: The life of the motor was investigated by performing the accelerated life test with the brush wear of the industrial cleaner motor as the main failure mode. Through the accelerating test method of the cleaner motor, various life expectancy and life expectancy of the acceleration factor are predicted.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.8
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• pp.625-631
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• 2009

In this thesis, lateral thermosonic bonding with ACFs was investigated as a process to make high reliability joints for FPD fabrication. Conditions for thermosonic and thermocompression bonding with ACFs were determined and used to make specimens in a driving test jig for testing of bond reliability by thermal shock. The results showed that thermosonic bonding temperature of $199\;^{\circ}C$ and bonding time of 1s produced bonds with good reliability. Additionally, thermosonic bonding temperature and time were reduced and thermal shock test results compared to this proposed curing condition. It is concluded that theromosonic bonding with ACFs can be effectively applied to reduce bonding temperature and time compared with that of thermocompression bonding.

• Korean Journal of Adult Nursing
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• v.21 no.2
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• pp.235-244
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• 2009

Purpose: This research was carried out to evaluate the validity and reliability of the Korean version of the Summary of Diabetes Self-Care Activities Questionnaire (SDSCA) for Korean older adults with type 2 diabetes. Methods: Translation and back-translation were performed to develop the Korean version of the SDSCA. Then the Korean version SDSCA was applied to a sample of 112 older adults who had participated in diabetes self management education in Seoul. The internal consistency and the test-retest reliability were examined to test the reliability. Factor analysis was used to examine the construct validity. Results: The internal consistency measured with Cronbach's alpha was .77 and the total test-retest reliability was .68 with items ranging from .21 to 1.00. As the result of the factor analysis, six factors -foot care, diet, exercise, blood sugar test, medication, and smoking- were revealed as the original instrument subcategories. These six factors explained 81.17% of total variance. Conclusion: The reliability and validity of the Korean version SDSCA Questionnaire was supported for use in older patients with type 2 diabetes in Korea.

• Journal of Audiology & Otology
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• v.25 no.1
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• pp.14-21
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• 2021

Background and Objectives: There is growing interest in the use of the Level-specific (LS) CE-Chirp^® stimulus in auditory brainstem response (ABR) due to its ability to produce prominent ABR waves with robust amplitudes. There are no known studies that investigate the test-retest reliability of the ABR to the LS CE-Chirp^® stimulus. The present study aims to investigate the test-retest reliability of the ABR to the LS CE-Chirp^® stimulus and compare its reliability with the ABR to standard click stimulus at multiple intensity levels in normal-hearing adults. Subjects and Methods: Eleven normal-hearing adults participated. The ABR test was repeated twice in the same clinical session and conducted again in another session. The ABR was acquired using both the click and LS CE-Chirp^® stimuli at 4 presentation levels (80, 60, 40, and 20 dBnHL). Only the right ear was tested using the ipsilateral electrode montage. The reliability of the ABR findings (amplitudes and latencies) to the click and LS CE-Chirp^® stimuli within the same clinical session and between the two clinical sessions was calculated using an intra-class correlation coefficient analysis (ICC). Results: The results showed a significant correlation of the ABR findings (amplitude and latencies) to both stimuli within the same session and between the clinical sessions. The ICC values ranged from moderate to excellent. Conclusions: The ABR results from both the LS CE-Chirp^® and click stimuli were consistent and reliable over the two clinical sessions suggesting that both stimuli can be used for neurological diagnoses with the same reliability.

• Korean Journal of Audiology
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• v.25 no.1
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• pp.14-21
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• 2021

Background and Objectives: There is growing interest in the use of the Level-specific (LS) CE-Chirp^® stimulus in auditory brainstem response (ABR) due to its ability to produce prominent ABR waves with robust amplitudes. There are no known studies that investigate the test-retest reliability of the ABR to the LS CE-Chirp^® stimulus. The present study aims to investigate the test-retest reliability of the ABR to the LS CE-Chirp^® stimulus and compare its reliability with the ABR to standard click stimulus at multiple intensity levels in normal-hearing adults. Subjects and Methods: Eleven normal-hearing adults participated. The ABR test was repeated twice in the same clinical session and conducted again in another session. The ABR was acquired using both the click and LS CE-Chirp^® stimuli at 4 presentation levels (80, 60, 40, and 20 dBnHL). Only the right ear was tested using the ipsilateral electrode montage. The reliability of the ABR findings (amplitudes and latencies) to the click and LS CE-Chirp^® stimuli within the same clinical session and between the two clinical sessions was calculated using an intra-class correlation coefficient analysis (ICC). Results: The results showed a significant correlation of the ABR findings (amplitude and latencies) to both stimuli within the same session and between the clinical sessions. The ICC values ranged from moderate to excellent. Conclusions: The ABR results from both the LS CE-Chirp^® and click stimuli were consistent and reliable over the two clinical sessions suggesting that both stimuli can be used for neurological diagnoses with the same reliability.

• The Journal of Korean Physical Therapy
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• v.27 no.4
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• pp.183-189
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• 2015

Purpose: The aim of this study was to examine the test-retest and inter-rater reliability of the pediatric functional muscle testing (PFMT) when applied to children with developmental delay. Methods: Sixteen children with developmental delay (seven females, nine males) participated in this study. For the inter-rater reliability, each was scored on the PMFT by two pediatric physical therapists with more than 8 years of clinical experience on the same day. For assessment of the test-retest reliability, one therapist tested the children again within 10 days. The second measurement was performed by taking a first measurement in video. Intraclass correlation coefficient (ICC) was calculated to determine the test-retest and inter-rater reliability of the PFMT, and Chronbach's alpha was used to measure internal consistency. Results: The results of this study were as follows: 1) The test-retest ICC of the score of the infant action month and the right side of the PFMT was from 0.53 to 1.00 and from 0.63 to 0.99, respectively. 2) The inter-rater ICC of the score of the infant action month and the right side of the PFMT was from 0.66 to 1.00 and from 0.64 to 1.00, respectively. 3) Chronbach's alpha was 0.93. The internal consistency indicated excellent. Conclusion: In conclusion, this study showed that the test-retest and inter-rater reliability of the PFMT was relatively high, except for a few items. Therefore, it can be suggested that the PFMT will be a useful tool for measurement of muscle strength for children with developmental delay if it be some modifications.

• Journal of Applied Reliability
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• v.16 no.4
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• pp.287-294
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• 2016

Purpose: Environment test support is urgent for small and medium defense companies in order to improve the reliability of weapons systems. Also, to reduce the burden of test costs, the voucher system must be strengthened. Quality assurance support should be accompanied by budget support. Methods: First of all, it is necessary to expand infrastructure for test equipment that suffers shortages by considering environmental test frequency and waiting periods to reduce the time required for environmental tests. Results: In regard to the environmental test, expansion for test equipment infrastructure, security of budget for the test, establishment of test plan, education and consulting support are required to resolve some limits of small and medium defense companies. Conclusion: Along with the opening of environmental test courses for industry operators, the expansion for consulting support projects of the defense industry support system is needed.

• Journal of Korean Institute of Industrial Engineers
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• v.43 no.2
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• pp.147-153
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• 2017

In order to demonstrate a target reliability with a specified confidence level, a new two-stage Bayesian Reliability Demonstration Test (RDT) plans that is known to be more effective than a corresponding single-stage one is proposed and developed by Bayesian framework with beta prior distribution for Weibull life time distribution. A numerical example is provided to illustrate the proposed RDT plans and compared with other non-Bayesian and Bayesian plans. Comparative results show that the proposed Bayesian two-stage plans have some merits in terms of required and expected testing time and probability of acceptance.

• Journal of Drive and Control
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• v.19 no.3
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• pp.32-38
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• 2022

The in-wheel drive gearbox for military special vehicles converts the high-speed & low-torque output generated by the electric servomotor, into low-speed & high-torque mechanical power. As the vehicle is remotely maneuvered in mountainous terrain, wet fields, rough terrain, etc., the gearbox must generate a maximum input speed exceeding 5,000 rpm, a maximum torque of 245 Nm, and MTBF of 9,600 km. The purpose of this study was to analyze the failure mode of the gearbox, to ensure the durability of the in-wheel drive gearbox. Also, the field load test data of the vehicle was analyzed, the acceleration durability test standards were established, the acceleration durability test was conducted, and the durability test results were analyzed as well.