냉장고용 압축기의 무고장시험시간 주요 변수들의 영향 분석

변종영 (J. Y. Byun ),주우진 (W. J. Joo ),정태영 (T. Y. Jeong ),정영미 (Y. M. Jeong ),정석권 (S. K. Jeong ) 한국동력기계공학회 2009 한국동력기계공학회 학술대회 논문집 Vol.2009 No.6

This paper evaluates the influences of variables related to accelerated life test time for a compressor in a refrigerator to guarantee qualification life of it. At first, some equations applied to real industrial field for evaluating accelerated life test time are introduced. Then we investigate influences of the variables of the equations effected on the test time. Finally, we analyze the times obtained from each equation which is necessary for testing the compressor. It will be expected that relations between each equation can be cleared. Therefore, we can conduct accelerated life test of a refrigerator"s compressor within optimized minimum test time.

Accelerated life-time test protocols for polymer electrolyte membrane fuel cells operated at high temperature

Jeon, Y.,Na, H.,Hwang, H.,Park, J.,Hwang, H.,Shul, Y.g. Pergamon Press ; Elsevier Science Ltd 2015 International journal of hydrogen energy Vol.40 No.7

Durability of high temperature fuel cells with low humidity has been receiving attention for its commercialization into the automobile. Therefore, advanced durability protocols are designed to evaluate the membrane electrode assembly (MEA) composed of short-side-chain conducting polymer (Aquivion(TM)) at the high temperature of 120 <SUP>o</SUP>C and low humidity of 40%RH. Accelerated life time tests (ALTs) of on-off cycle test with the duration time of 10 min and load cycle test with a voltage sweep of 0.6 V-1.0 V and a duration of 4.25 min, are developed to induce different stresses. The different degradation behaviors of the MEAs are monitored and compared to the normal constant voltage mode of 0.6 V. The decay rate using the on-off cycle test is 0.113 mA/(cm<SUP>2</SUP> min) whereas a slightly slower decay rate of 0.096 mA/(cm<SUP>2</SUP> min) is obtained for the load cycle test. The electrochemical analyses of membrane electrode assembly (MEA) are confirmed periodically during the tests for each protocol using polarization curve, impedance spectroscopy and cyclic voltammetry. The characterizations of the MEA are carried out before and after the durability tests to verify the material degradation and failure mechanisms. Although both protocols show similar degradation on the MEA materials, the membrane degradation is more dominant after the on-off test while more catalyst degradation is observed after the load cycling test. Nafion<SUP>®</SUP> is also tested by the developed load cycle test to observe the difference between short-side-chain and long-side-chain conducting polymer.

냉동시스템의 압축기 신뢰성 시험 기간 단축을 위한 가속계수 설정

변종영(J. Y. Byun),이화(H. Li),정태영(T. Y. Jeong),정석권(S. K. Jeong) 한국동력기계공학회 2008 한국동력기계공학회 학술대회 논문집 Vol.2008 No.11

Compressor is a major component of a refrigeration system. Therefore many attempts to progress performances of the compressor have been conducted. The reliability qualification test is essential when a new product of a compressor is developed to guarantee life of the product under normal operation conditions. If the number of test sample is limited, the test period will be increase inevitably. In order to reduce the test period, we have to obtain an acceleration factor as some value through an acceleration life test. The process and methodology to establish the acceleration factor are investigated in this paper. The Weibull distribution and the Arrhenius relationship are adopted to estimate the acceleration factor under given assumptive temperature data. Finally a stress condition to satisfy the acceleration factor was formulated.

Life Time Prediction Using Accelerated Ageing Test for a CR/CB Rubber Composite

( Wonsool Ahn ),( Hyung Seok Lee ) 한국고무학회 2017 엘라스토머 및 콤포지트 Vol.52 No.4

The tensile strength (TS) and elongation-at-break (EB) loss of a CR/CB rubber composite sample prepared for the automotive parts were measured after accelerated thermal ageing at temperatures of 100, 120, 140, and 150℃. The change in TS was observed to be linear from the master curve prepared using the time-temperature superposition-principle (TTSP). An Arrhenius type of shift factor, a_T was used to predict the life time of the sample, and a plot of ln a_T vs. 1/T was also shown to be linear. The activation energy (E_a) of the sample was calculated as 70.30 kJ/mole from the Arrhenius plot. The expected life time of the sample was predicted at the given operating conditions by applying Arrhenius analysis. Assuming the E_a value was constant at lower operating condition, life time of the sample was calculated as 2.3 years when the life limit was set as time to reach the 20% decrease of the initial TS value at operating temperature of 40℃.

Accelerated Life-time Tests including Different Load Cycling Protocols for High Temperature Polymer Electrolyte Membrane Fuel Cells

Jeon, Y.,Juon, S.m.,Hwang, H.,Park, J.,Shul, Y.g. Pergamon Press 2014 ELECTROCHIMICA ACTA Vol.148 No.-

The purpose of this work is to identify new accelerated life-time (ALT) test protocols for polymer electrolyte membrane fuel cell (PEMFC), which function at conditions of high temperature and low humidity (under 120<SUP>o</SUP>C 40%RH). A design of accelerated life protocols was studied to observe degradation phenomena under different load step cycling conditions, compared with the constant voltage test at 0.6V. The effects of changes in frequency and potential range are explored, and different degradation rates are revealed. The test protocol of constant voltage test, load step cycling and with different potential range show total performance decay rates of 5.3mA.cm<SUP>-2</SUP>.h<SUP>-1</SUP>, 8.4mA.cm<SUP>-2</SUP>.h<SUP>-1</SUP> and 10.2mA.cm<SUP>-2</SUP>.h<SUP>-1</SUP>, respectively, while the highest total decay rate of load step cycling with frequency change is 17.0mA.cm<SUP>-2</SUP>.h<SUP>-1</SUP> including a rapid decrease of current density after 450 cycles under 120<SUP>o</SUP>C 40%RH. In respect to the operation of 500 cycles (35h), material degradation failure mechanisms are investigated according to the electro- and physico-chemical characteristics of the MEA. The performances assessed by the life-time evaluation methods are strongly related to the increase in the membrane resistance and the release of the sulfate and fluoride ions, dominated more at a higher cycling frequency. Furthermore, in the contrast to the starting MEA, Pt aggregations of the catalysts and a decline in the electrochemical surface area (ECSA) are clearly observed at the end of the testing especially with a wider sweeping range, corresponded to the decrease in the electrochemical properties.

학술 7 특별구두세션 : PB. 포스터세션2 ; 시그마 방법론에 의한 LED 가속수명방법 제안

전상호 ( Sang Ho Jeon ),한택환 ( Ta다 Whan Han ),이상복 ( Sang Bok Ree ) 한국품질경영학회 2014 한국품질경영학회 학술대회 Vol.2014 No.2

Nowadays, it has recently been increasing demand for accelerated lifetime as a way to as-sess the reliability of the product in a short time. However, lack of a systematic examination of the statistical analysis of the activity factors and life analysis of activity of the electronic component. Each step was carried out according to the plan of accelerated life test LED through the Six Sigma methodology for this reason. Management process, and propose an effective method to increase the efficiency of the accelerated life test method was demon-strated to contribute to progress. 6 sigma methodology is proposed to accelerate the life of a reliable field method first process. The test was performed in a 16-step proof of the Six Sigma methodology to estimate the distribution, not the name of an existing test.

유압구동장치 동력원용 고무 다이아프램 저유기의 수명 예측 연구

김솔아(Sol A Kim) 유공압건설기계학회 2021 드라이브·컨트롤 Vol.18 No.2

The piston reservoir is mainly used in hydraulic blow-down system for aerospace engineering. The reservoir is heavy due to both hydraulic cylinder and piston in pressurization. The positive expulsion tank with rubber diaphragm has been mostly applied propellant and fuel tank at low pressure to satellites. To reduce weight, the reservoir that can be used at high pressure with rubber diaphragm was developed. In this research, the prediction of life-time for the rubber diaphragm was implemented through an accelerated life test, as a part of development of new reservoir. Also, the diaphragm was stored in an temperature chamber at the same condition as and operation with hydraulic oil. As a result, the life-time for a rubber diaphragm was successfully evaluated via Arrhenius law and Time-Temperature Superposition based on failure times over temperatures in the accelerated test.

가속수명시험에 의한 고속팬용 밀폐구조형 BLDC 모터의 열신뢰성 분석

이태구,문종선,유호선,이재헌 대한설비공학회 2005 설비공학 논문집 Vol.17 No.12

In this paper, thermal reliability of a closed type BLDC(Brushless DC) motor for high speed axial fan was analyzed by the accelerated life test. The closed type BLDC (Model No. MB1-8855-J01) motor was controlled by PCB module, which was composed of various electrical components. The failure of the closed type BLDC motor happened in PCB module due to high temperature. Failure mechanism of the closed type BLDC motor appears to be electrolyte dry out of capacitor. The accelerate life test was performed in temperature stress of 85℃ and 105℃, respectively. The failure data from the accelerated life test were analyzed and the life in each stress level was estimated with 960h and 261h. At last, both life expression according to operating temperature of PCB module and life of the closed type BLDC motor in normal condition(50℃) were suggested.

파괴적 가속열화시험 데이터의 분산가정에 따른 수명비교

김종규,백승준,손영갑,박상현,이문호,강인식 한국군사과학기술학회 2018 한국군사과학기술학회지 Vol.21 No.2

Estimating reliability of a non-repairable system using the degradation data, variance assumption such as homogeneity (constant) or heteroscedasticity (time-variant) could affect accuracy of reliability estimation. This paper showed reliability estimation and comparison results under normal conditions using accelerated degradation data obtained from destructive measurements, according to variance assumption of the data at each measurement time. Degradation data from three accelerated conditions with stress factors of temperature and humidity were used to estimate reliability. The B10 lifetime was estimated as 1243.8 years by constant variance assumption, and 18.9 years by time-variant variance. And variance assumption provided different analysis results of important stresses to reliability. Thus, accurate assumption of variance at each measurement time is required when estimating reliability using degradation data of a non-repairable system.

기만기 적용 고무 O-ring의 온도에 따른 가속수명시험을 통한 수명예측에 관한 연구

조희진(Hee-Jin Jo),김민우(Minwoo Kim),곽혜림(Hyerim Gwak) 한국산학기술학회 2016 한국산학기술학회논문지 Vol.17 No.10

어뢰회피용 기만기는 수중에서 적 어뢰의 공격으로부터 자함을 보호하는 무기체계로 유사 시 우리 군의 피해를 최소화하기 위해 운용 간 고장없이 정상적으로 임무를 수행하여야 한다. 기만기는 운영 특성 상 내부로 해수가 유입되면 정상적인 임무 수행이 불가하기 때문에 운용환경을 고려하여 외부로부터 해수유입 방지를 위한 완벽한 기밀이 요구된다. 일반적으로 기만기의 수밀성능 확보를 위해 고무재질의 오링을 사용하는데 이러한 고무재질의 제품들은 시간의 경과와 주변 환경의 영향을 받아 노화되어 고무 초기 특성이 상실되어진다. 따라서 요구되는 수밀성능을 유지하기 위해 오링에 대한 정비 또는 교체가 필수적이다. 본 논문에서는 기만기에 사용되는 오링의 대표적인 물성 지표인 경도와 신장률 값을 기준으로 오링의 가속수명시험 수행을 통한 시험데이터를 바탕으로 적합한 정비주기를 선정하는 것을 목적으로 한다. 기만기 수밀성능을 보장하기 위해 사용되는 오링의 재질은 NBR(Nitrile Butadiene Rubber)로써, 선행 연구 자료를 참고하여 주요 고장 환경 인자를 온도로 선정하였으며, 고장의 기준은 대상 제품이 가지는 물성 값 중 경도와 신장률이 초기 대비 50%까지 저하되는 시점으로 선정하였다. 또한 시험에 사용되는 시편 준비 및 물성 값 측정방법은 KS M 6518 규격을 참고하여 진행하였다. 시험결과는 컴퓨터 프로그램을 통해 분석하여 기만기에 적용되는 오링의 수명을 예측하였으며, 이를 통해 오링에 대한 정비주기를 산출하였다. A decoy is a weapon system that can protect vessels from an enemy"s torpedo. Thus, the decoy should be able to operate in the field without any failure. Because the decoy can be inoperable once its sealing is broken and water permeates inside the system, the hermetic sealing capability considering the operational environment is mandatory. To be hermetically sealed, a rubber-type O-ring is generally used in a decoy system. The sealed performance of rubber-type products, however, tends to age and deteriorate with time. Therefore, the O-ring needs to be maintained or changed periodically. This paper proposes a method to estimate the proper maintenance period using the hardness and elongation percentage, which represents the performance of the O-ring product and test data from Accelerated Life Test (ALT) of the product. The O-ring used in this paper is a NBR type, and the temperature was chosen to be the main accelerating factor as referenced in many studies. The criteria for the failure of the O-ring was set for the product to be 50% degraded compared to the initial performance. In addition, the Korean standard KS M 6518 was adopted and referenced for the preparation of test samples and the calculation of estimates. The O-ring"s predicted life was simulated by analyzing the test results from a computer program, and the optimized maintenance period for the product was determined.