• Title/Summary/Keyword: reliability factors

Search Result 4,307, Processing Time 0.045 seconds

Reliability-based Design Optimization on Mobility of Deep-seabed Test Miner Using Censored Data of Current Speed (중도절단 해류속도자료를 이용한 심해저 시험집광기의 주행성능에 관한 신뢰성 기반 최적설계)

  • Park, Sanghyun;Cho, Su-Gil;Lim, Woochul;Kim, Saekyeol;Choi, Sung Sik;Lee, Minuk;Choi, Jong-Su;Kim, Hyung-Woo;Lee, Chang-Ho;Hong, Sup;Lee, Tae Hee
    • Ocean and Polar Research
    • /
    • v.36 no.4
    • /
    • pp.487-494
    • /
    • 2014
  • Deep-seabed test miner operated by a self-propelled mining system moving on soft soil is an essential device to secure floating and towing performances. The performances of the tracked vehicle are seriously influenced by noise factors such as the shear strength of the seafloor, bottom current, seafloor slope, speed of tracked vehicle, reaction forces of flexible hose, steering ratio, etc. Due to uncertainties related to noise factors, the design of a deep-sea manganese nodules test miner that satisfies target reliabilities is difficult. Therefore, reliability-based design optimization (RBDO) is required to guarantee system reliability under circumstances where uncertainties related to noise factors prevail. Among noise factors, the bottom current, a bimodal distribution, is censored due to the observation limit of measurement devices. Therefore, estimated distribution of the bottom current is inaccurate without considering these characteristics and the result of RBDO cannot be guaranteed. In this paper, we define censored data as unknown values over the limit of observation. If this data is estimated by using Akaike information criterion (AIC) that cannot consider the characteristics of censored data, the distribution of estimated data cannot guarantee accurate reliability. Therefore, censored AIC that can consider the characteristics of data is used to estimate accurate distribution of the bottom current. Finally, RBDO, under circumstances where uncertainties related to noise factors combined censored data are present, is performed on the mobility of a deep-sea manganese nodules test miner.

Methodologies of Duty Cycle Application in Weapon System Reliability Prediction (무기체계 신뢰도 예측시 임무주기 적용 방안에 대한 연구)

  • Yun, Hui-Sung;Jeong, Da-Un;Lee, Eun-Hak;Kang, Tae-Won;Lee, Seung-Hun;Hur, Man-Og
    • Journal of Applied Reliability
    • /
    • v.11 no.4
    • /
    • pp.433-445
    • /
    • 2011
  • Duty cycle is determined as the ratio of operating time to total time. Duty cycle in reliability prediction is one of the significant factors to be considered. In duty cycle application, non-operating time failure rate has been easily ignored even though the failure rate in non-operating period has not been proved to be small enough. Ignorance of non-operating time failure rate can result in over-estimated system reliability calculation. Furthermore, utilization of duty cycle in reliability prediction has not been evaluated in its effectiveness. In order to address these problems, two reliability models, such as MIL-HDBK-217F and RIAC-HDBK-217Plus, were used to analyze non-operating time failure rate. This research has proved that applying duty cycle in 217F model is not reasonable by the quantitative comparison and analysis.

Deterministic and reliability-based design of necessary support pressures for tunnel faces

  • Li, Bin;Yao, Kai;Li, Hong
    • Geomechanics and Engineering
    • /
    • v.22 no.1
    • /
    • pp.35-48
    • /
    • 2020
  • This paper provides methods for the deterministic and reliability-based design of the support pressures necessary to prevent tunnel face collapse. The deterministic method is developed by extending the use of the unique load multiplier, which is embedded within OptumG2/G3 with the intention of determining the maximum load that can be supported by a system. Both two-dimensional and three-dimensional examples are presented to illustrate the applications. The obtained solutions are validated according to those derived from the existing methods. The reliability-based method is developed by incorporating the Response Surface Method and the advanced first-order second-moment reliability method into the bisection algorithm, which continuously updates the support pressure within previously determined brackets until the difference between the computed reliability index and the user-defined value is less than a specified tolerance. Two-dimensional reliability-based support pressure is compared and validated via Monte Carlo simulations, whereas the three-dimensional solution is compared with the relationship between the support pressure and the resulting reliability index provided in the existing literature. Finally, a parametric study is carried out to investigate the influences of factors on the required support pressure.

A Study on the Reliability Demonstration for Korea High Speed Train Control System (한국형고속철도 열차제어시스템 하부구성요소 신뢰도입증에 관한 연구)

  • Lee, Jae-Ho;Lee, Kang-Mi;Kim, Young-Kyu;Shin, Duc-Ko
    • Journal of the Korean Society for Railway
    • /
    • v.9 no.6 s.37
    • /
    • pp.732-738
    • /
    • 2006
  • This research provides a scheme for Highly Accelerated Stress Test that is necessary to demonstrate reliability prediction of Korean Rapid Transit Railway Train Control System sub-equipment, which is calculated by a relevant standard for failure rate prediction of electronic products. Although determining failure information generated in the process of trial running by statistic analysis is widely accepted as a measure of confirmation for reliability prediction, this research suggests the modeling for System Life Test determined by accelerating stress factors as a measure of confirmation for reliability prediction of sub-equipment unit that is generated ahead of a trial running in System Life Cycle. Consequently, the research demonstrates sub-equipment unit reliability test, which is based on the model derived from Accelerated Stress Test, according to accuracy level and the number of samples, and conducts an official experiment by making out a reliability test procedure sheet based on test time as well.

Development of a Reliability Index using Design, Development and Production Information (설계, 개발 및 양산 정보를 활용한 신뢰성 지수 개발)

  • Kim, Sung Kyu;Park, Jung Won;Kim, Yong Soo
    • Journal of Korean Society for Quality Management
    • /
    • v.43 no.3
    • /
    • pp.373-382
    • /
    • 2015
  • Purpose: In this paper, we developed a reliability index (RI) to efficiently compare reliability of products based on the design, development and production information such as reliability tests, quality, product life-cycle management. RI also can be applied to reliability prediction of a novel product as well as comparison evaluation among existing products. Methods: For evaluating RI, we proposed evaluation process which is composed of five steps. Target modules are selected based on warranty data and correlation analysis. Scores of selected target modules are calculated by scoring function. Finally, weights of RI model are determined by optimization method. Results: This paper presented an empirical analysis based on failure data of mobile devices. In this case study, we demonstrated that there is a direct correlation between evaluated RI and field failure probability of each product. Conclusion: We proposed the index for comprehensive and effective assessment of product reliability level. From the procedure of this study, we expected to be applied for reliability estimation of novel products and deduction of field failure-related factors.

Effects of Verbal and Nonverbal Communication Subfactors on Purchase Intention through Empathy and Product Reliability

  • Ha-Eun Jeong;Mi Young Kim
    • Journal of the Korean Society of Clothing and Textiles
    • /
    • v.46 no.6
    • /
    • pp.1161-1179
    • /
    • 2022
  • In this study, the effects of show host's verbal communication subfactors, such as paralanguage, friendliness, and professionalism, as well as nonverbal communication subfactors, such as demonstration attitude, appearance, and attractiveness, on purchase intention were examined by evaluating customer empathy and product reliability. Data was collected from 20s-50s females. SPSS 23.0 and AMOS 23.0 were used for data analysis. The results revealed that professionalism and friendliness had a positive impact on customer empathy; however, friendliness had a negative impact on product reliability. Moreover, nonverbal communication subfactors had a positive impact on empathy, and appearance had a positive impact on product reliability. In contrast, attractiveness had a negative impact on product reliability, whereas empathy and product reliability had a positive impact on purchase intention. Thus, ensuring appropriate verbal and nonverbal communication is essential for customer empathy and product reliability. Given that a show host's friendliness, professional verbal communication, demonstration attitude, appearance, and attractiveness have a positive impact on customer empathy, these factors should be considered critical qualities of show hosts.

Reliability of a Newly Developed Tool to Assess and Classify Work-related Stress (TAWS-16) for Indian Workforce

  • Gautham Melur Sukumar;Runalika Roy;Mariamma Philip;Gururaj Gopalkrishna
    • Journal of Preventive Medicine and Public Health
    • /
    • v.56 no.5
    • /
    • pp.407-412
    • /
    • 2023
  • Objectives: Work stress is associated with non-communicable diseases, increased healthcare costs, and decreased work productivity among employees in the information technology sector. There is a need for regular work-stress screening among employees using valid and reliable tools. The Tool to Assess and Classify Work Stress (TAWS-16) was developed to overcome limitations in existing stress assessment tools in India. This study aimed to test the reliability of TAWS-16 in a sample of managerial-supervisory employees. Methods: This observational reliability study included data from 62 employees. Test-retest and inter-method reliability were investigated using a TAWS-16 web application and interview by telephone, respectively. Kappa values and intra-class correlation coefficients were calculated. Internal consistency was assessed through Cronbach's alpha. Results: For both test-retest and inter-method reliability, the agreement for both work-related factors and symptoms suggestive of work stress exceeded 80%, and all kappa values were 0.40 or higher. Cronbach's alpha for test-retest and inter-method reliability was 0.983 and 0.941, respectively. Conclusions: TAWS-16 demonstrated acceptable reliability. It measured stressors, coping abilities, and psychosomatic symptoms associated with work stress. We recommend using TAWS-16 to holistically identify work stress among employees during periodical health check-ups in India.

Study on UX Satisfaction Index According to Types of Mobile Commerce Services (모바일 커머스 서비스의 유형별 UX 만족도 지표 연구)

  • Kim, Sohyun;Ha, Hyunnam
    • Journal of the HCI Society of Korea
    • /
    • v.9 no.2
    • /
    • pp.53-59
    • /
    • 2014
  • The objectives of this research is to compare UX elements influencing the satisfaction of users in Korea and North America according to product types of mobile commerce services, to determine UX INDEX suitable for each type of service, and to derive positively influencing UI factors through analyzing the relationship between UX INDEX and UX design detail factors. This research showed that there was difference in perceived reliability according to selling product types and there was difference in both perceived usefulness and reliability according to users in Korea and North America. Also, this research found out that, in analysis of relationship between UX INDEX and UX design detail factors, UI factors to understand a service structure generally showed close relationship but factors such as troubleshooting and help showed difference between users in Korea and users in North America.

A Study on Positioning of Nursing Service Image in General Hospital;Centering around 5 General Hospitals in Seoul (종합병원의 간호 서비스 이미지 포지셔닝 연구;서울시내 5개 병원을 중심으로)

  • Lim, Ji-Young
    • Journal of Korean Academy of Nursing Administration
    • /
    • v.5 no.2
    • /
    • pp.369-388
    • /
    • 1999
  • This study is a descriptive research to establish a positioning strategy of nursing service image, making a perception map on each hospital's nursing service image and ranking construct factors of nursing service image. The results in this study were as follows; 1. The rank of construct factors of nursing service image which were thought important by subjects was the first 'Kindness', the second 'Reliability', the third 'Professional Knowledge', the fourth 'Responsibility', and the fifth 'Advanced Nursing Skill'. 2. The perception map for nursing service image on each hospital showed a hierarchial structure and positioned the first B hospital, the second C hospital, the third D hospital, the fourth A hospital, and the fifth E hospital. The perception map for construct factors of nursing service image and hospitals showed the first dimension : 'Reliability', the second dimension : Kindness', the third dimension : 'Mission', 'Accuracy', 'Neat Appearance', and 'Ethical Aspect', and the fourth dimension : 'Client Advocate', 'Humanistic Consideration', 'Professional Knowledge', 'Responsibility', and 'Advanced Nursing Skill'. 3. The findings of subject's characteristics which affected degree of likeness on each hospital nursing service image to make a marketing strategy were as follows : In A hospital D hospital, and E hospital, the subject group whose hospital dates were under 1 week, education level was upper graduate university, and age was between 40's and 50's, were appeared to have low nursing service image on following construct factors : 'Kindness', 'Reliability', 'Responsibility', 'Mission', 'Neat Appearance', and 'Humanistic Consideration'. In B hospital and C hospital the subject group whose hospital dates were under 1 week or over 5 weeks, sex was woman, and age was 20' s or 40's, having a admission experience on subject hospitals, were appeared to have low nursing service image on following construct factors : 'Professional Knowledge', 'Advanced Nursing Skill', 'Ethical Aspect', and 'Humanistic Consideration'. As the based on above results, nursing managers can use positioning method to develope a marketing strategy for nursing service image.

  • PDF

Assessment of a Questionnaire for Breast Cancer Case-Control Studies

  • Strumylaite, Loreta;Kregzdyte, Rima;Rugyte, Danguole Ceslava;Bogusevicius, Algirdas;Mechonosina, Kristina
    • Asian Pacific Journal of Cancer Prevention
    • /
    • v.14 no.5
    • /
    • pp.2777-2782
    • /
    • 2013
  • The aim of the present study was to assess criterion validity and external reliability of a questionnaire on risk factors for breast cancer. Materials and Methods. Women with breast cancer diagnosis (the cases) (N=40) and matched individuals without cancer (the controls) (N=40) were asked to fill in a questionnaire twice: on a day of admission to hospital (Q1) and on a day before discharge (Q2), with a time interval of 4-6 days. The questionnaire included questions (N=150) on demographic and socioeconomic factors, diseases in the past, family history of cancer, woman's health, smoking, alcohol use, diet, physical activity, and work environment. Criterion validity of the questionnaire Q2 relative to reference questionnaire Q1 was assessed with the Spearman correlation coefficient (SCC); external reliability of the questionnaire was measured in terms of the intraclass correlation coefficient (ICC). Statistical analysis was performed with SPSS 16. Results. The responses to most of the questions on socioeconomic factors, family history on cancer, female health, lifestyle risk factors (smoking, alcohol use, physical activity) correlated substantially in both the cases and the controls with SCC and ICC>0.7 (p<0.01). Statistically non significant relationships defined only between the responses on amount of beer the cases drank at the ages up to 25 years and 26-35 years as well as time of use of estrogen and estrogens-progestin during menopause by the cases. Moderate and substantial SCC and ICC were determined for different food items. Only the response of the cases on veal consumption did not correlate significantly. Conclusions. The questionnaire on breast cancer risk factors is valid and reliable for most of the questions included.