• 한국신뢰성학회지:신뢰성응용연구
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• 제15권4호
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• pp.241-247
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• 2015

Purpose : The demand for higher fuel economy vehicles has helped develop fuel-efficient vehicles such as a CVVL called continuous variable valve lift. Existing CVVL has been applying DC type motor to control intake valve, but recently some car parts manufacturers have been developing a BLDC type CVVL motor for improvements of endurance performance. The purpose of this study is to find the potential failure mechanism of the CVVL BLDC moto in early stage of development based on the design properties and design the accelerated life test model. Methods : CVVL BLDC is consist of brushs, coil, magnetic, PCB, bearing and so on. Each component has a latent failure mechanism caused by temperature, humidity, vibration. By analysis result of the failure mechanism, thermal fatigue is the most important factor of a durability of CVVL BLDC motor. So, we designed a new accelerated life test model for guarantee of the CVVL BLDC motor. Results : A crack occurred on via hole in test using the conditions we designed, so we did change the design to avoid this failure. The via hole dimension is changed a little larger, as a result we achieve improvements in reliability of the CVVL BLDC motor. By applying various kinds and extreme level of stresses, we can find the operating limits of products. Conclusion : In thesis, We analyzed the failure mechanism of CVVL BLDC and designed an accelerated life test method to give a guarantee for reliability. Based on the test results, we could improve the reliability of developments by change of design.

• 한국신뢰성학회지:신뢰성응용연구
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• 제15권2호
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• pp.90-100
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• 2015

Reliability growth rate (or reliability growth curve slope) have the two cases of trend as a constant or changing one during the reliability growth testing. The changing case is very common situation. The reasons of reliability growth rate changing are that the failures to follow the NHPP (None-Homogeneous Poisson Process), and the solutions implemented during test to break out other problems or not to take out all of the root cause permanently. If the changing were big, the "Goodness of Fit (GOF)" of reliability growth curve to test data would be very low and then reduce the accuracy of assessing result with test data. In this research, we are using Duane model and AMSAA model for assessing test data and projecting the reliability level of complex and repairable system as like construction equipment and vehicle. In case of no changing in reliability growth rate, it is reasonable for reliability engineer to implement the original Duane model (1964) and Crow-AMSAA model (1975) for the assessment and projection activity. However, in case of reliability growth rate changing, it is necessary to find the method to increase the "GOF" of reliability growth curves to test data. To increase GOF of reliability growth curves, it is necessary to find the proper parameter calculation method of interesting reliability growth models that are applicable to the situation of reliability growth rate changing. Since the Duane and AMSAA models have a characteristic to get more strong influence from the initial test (or failure) data than the latest one, the both models have a limitation to contain the latest test data information that is more important and better to assess test data in view of accuracy, especially when the reliability growth rate changing. The main objective of this research is to find the parameter calculation method to reflect the latest test data in the case of reliability growth rate changing. According to my experience in vehicle and construction equipment developments over 18 years, over the 90% in the total development cases are with such changing during the developing test. The objective of this research was to develop the newly assessing method and the process for GOF level increasing in case of reliability growth rate changing that would contribute to achieve more accurate assessing and projecting result. We also developed the new evaluation method for GOF that are applicable to the both models as Duane and AMSAA, so it is possible to compare it between models and check the effectiveness of new parameter calculation methods in any interesting situation. These research results can reduce the decision error for development process and business control with the accurately assessing and projecting result.

• 한국의류산업학회지
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• 제17권6호
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• pp.965-977
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• 2015

This study aims to investigate determinants that included personal values, pro-environmental beliefs, and proenvironmental norms for enhancing consumers' purchase intention of eco-friendly outdoor wear exploring Stern(2000)’s the value-belief-norm theory. A survey was conducted with females and males between the ages of 20 and 60 who have experienced buying outdoor wear products. A total of 300 responses were analyzed by descriptive analysis, factor analysis, a reliability test, an independent samples t-test, and regression analysis. The results of this study were as follows: 1) The results of exploratory factor analysis and reliability test on the personal value clearly showed factorial structures including the social power, ecologic value, openness, equality, and altruistic value. 2) There are significant differences in personal value sub-dimensions, pro-environmental beliefs, pro-environmental norm, and purchase intention of eco-friendly outdoor wear products according to respondents' gender and age. 3) Personal values, but not social power, affect pro-environmental beliefs; in turn, pro-environmental beliefs affect pro-environmental norms, which then affects purchase intentions of eco-friendly outdoor wear. The findings support the conclusion that there is significant causality among personal value such as ecologic, openness, equality, and altruistic, pro-environmental belief, and pro-environmental norm. This study suggests pragmatic implications to understand outdoor wear consumers' socio-psychological and demographic factors and to augment purchase intentions of eco-friendly outdoor wear products.

• 정보과학회 논문지
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• 제42권1호
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• pp.76-85
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• 2015

소프트웨어 프로덕트라인 공학은 프로덕트 패밀리를 구성하는 프로덕트들의 공통성과 가변성을 분석하여 이를 바탕으로 프로덕트를 생산하는 방법이다. 소프트웨어 프로덕트라인 공학을 적용함에 있어 올바른 핵심자산을 구축하는 것이 매우 중요하며, 이를 달성하기 위해서는 공통성과 가변성의 명확한 구분, 추적성의 유지, 산출물의 신뢰성 보장 등이 선행되어야 한다. 본 논문에서는 공통성과 가변성의 명확한 구분을 위해 CVL 기반의 소프트웨어 프로덕트라인 개발 및 테스트 프로세스를 제안한다. 본 논문에서 제안하는 방법은 추적성의 유지와 산출물의 신뢰성 보장을 위한 추가적인 절차를 포함함으로써 올바른 핵심자산을 구축하도록 도와준다.

• KIEAE Journal
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• 제13권2호
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• pp.141-149
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• 2013

This paper aims to provide pragmatic application guidelines of the interior finish materials for apartment houses with newly-established evaluation methodology of the sustainable degree of interior products. With reference to the standards and criteria of domestic eco-labeling accreditation schemes for sustainable products in the area of architecture which focus on the sustainable elements classified as the health, recyclability, durability, and energy efficiency, in this study, a systematic evaluation method has been established for interior finish products with quantifiable indicators for sustainable performance. Base on the evaluation system introduced here, most interior finish products can be classified into a database and applied effectively to the realities from the perspective of the sustainability. There are the necessities of enforcement issues with the idea of revising or taking remedial measures of the current performance criteria of domestic eco-labeling accreditation to bolster their reliability. As well as already-commercialized products, hereafter, continued efforts are needed to control the whole process of manufacturing new interior finish products from their designing, constructing, consuming, recycling and to dismantling in terms of sustainability, which promises more pragmatic follow-up measures for the detail embodiment of the environment-friendly spaces.

• International Journal of Reliability and Applications
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• 제6권2호
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• pp.79-85
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• 2005

We show how comparative mean residual life functions (MRL) can be used to give unique insights into strengths of materials data. Recall that Weibull's original reliability function was developed studying and fitting strengths for various materials. This creative comparing of MRL functions approach can be used for regular life data or any time to response data. We apply graphical MRL's to real data from tests of tensile strength of high quality engineered wood.

• 한국산업경영시스템학회:학술대회논문집
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• 한국산업경영시스템학회 2002년도 춘계학술대회
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• pp.31-36
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• 2002

Product Liability(PL) is a legal policy to deal with global competition by improving domestic industrial competitive power and to reduce the cost of defect products. The purpose of this paper is to address the state of the art solutions to dispute on PL, in reality of a frequent occurrence of global product exchange focussing on product safety that is one of the most important functions of PL and to improve solution of the product safety and reliability responsive to PL. To minimize PL exposure, manufacturers should reflect comprehensive product safety and reliability concepts in establishing PL prevention policies. PL prevention policies are composed of administration system, product safety management system, and total quality management system in respect of prevention, safety, and defence.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1384-1389
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• 2004

In these days, wear resistance is an essential condition because the relative movement between machine parts is being accelerated and those connected with the drive parts transmit power and force. Also wear resistance is closely related to reliability and life of products, therefore the study on friction and wear is very important in many fields. In this paper, wear test was conducted to know properties about friction and wear of manganese phosphate being used widely. Test type is 1 ball on disk and we compared manganese phosphate thin film with non-coated material. Through this study, we could know the effect of this surface treatment method, and then it is assumed that the reliability of parts will be secure.

• 한국정밀공학회지
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• 제26권7호
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• pp.81-90
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• 2009

Due to environmental issues, the development of low energy consumption products has become one of the main topics in the home appliance industry. The energy consumption of a refrigerator depends on the efficiency of its compressor as well as on the refrigerator cycle design, such as the capacity modulation. In this study, a dual capacity, i.e., two-step capacity modulation (TCM), reciprocating compressor is developed. In a TCM compressor, capacity modulation is achieved by changing the dead volume in the cylinder. Instead of a concentric sleeve, an eccentric sleeve, a key, and a spring are used to change the dead volume for the clockwise and counterclockwise rotation of a motor. When the compressor changes its operating mode from full capacity to partial capacity or in opposite direction, the key may collide with the eccentric sleeve. The structural reliability and mode change reliability were confirmed by analysis and experiment.

• 한국신뢰성학회지:신뢰성응용연구
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• 제18권1호
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• pp.8-19
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• 2018

Purpose: This study has developed the accelerated lifetime test method for smps for outdoor lighting LED through two factors of temperature and humidity. Methods: Acceleration condition was confirmed for each stress and model, and acceleration life test model was estimated according to acceleration condition. Results: As a result of confirming the accelerated life test model, in the case of humidity, acceleration was established only in the foreign products. Therefore, it is confirmed that the acceleration condition is insufficient. However, the estimated parameters for temperature are relatively constant. It is therefore suitable for power supply acceleration tests for outdoor lighting LEDs. Conclusion: The SMPS acceleration test for outdoor lighting LED can improve the availability of the product by developing an accelerated life test method that guarantees the reliability of the product.