• 한국CDE학회논문집
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• 제18권1호
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• pp.36-48
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• 2013

In general, the product is used under several circumstances including environmental and usage conditions. According to the circumstances, the product has various performance degradation processes. In order to optimize the lifecycle of product usage, it is important to observe the degradation process and make suitable decisions on product operations. However, there are not much research works in evaluating the degree of product degradation based on product usage data. Recently, due to emerging ICT (Information and Communication Technology) technologies, it becomes possible to get the product usage data. Based on the gathered data, it is possible to analyze the degree of product degradation. The analysis of product usage data can improve product use and product design with advanced decisions. To this end, this study addresses one approach based on FMEA/FMECA method, called PDMCA (Performance, Degradation Modes and Criticality Analysis) for evaluating product degradation status and making suitable decisions.

• 한국신뢰성학회지:신뢰성응용연구
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• 제5권4호
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• pp.413-425
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• 2005

As an alternative to traditional life testing, degradation tests can be effective in assessing product reliability when measurements of degradation leading to failure can be observed. This article presents an accelerated degradation testing for vacuum fluorescent displays (VFDs). The accelerated degradation model is based on Arrhenius-lifetime relationship for cathode temperatures. We compare the results between accelerated degradation test and test at normal use condition. Accelerated degradation test for display devices is observed as an efficient method to warrantee product reliability to customers, as well as a tool to save time and costs.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.321-324
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• 2009

Upgrading of pyrolysis wax oil has been conducted in a continuous fixed bed reactor at $450^{\circ}C$, 1hour, LHSV 3.5/h. The catalytic degradation using HZSM-5 catalyst are compared with the thermal degradation and also was studied with a function of experimental variables. The raw pyrolysis wax oil shows relatively high boiling point distribution ranging from around $300^{\circ}C$ to $550^{\circ}C$, which has considerably higher boiling point distribution than that of commercial diesel. The product characteristic from thermal degradation shows a similar trend with that of raw pyrolysis wax oil. This means the thermal degradation of pyrolysis wax oil at high degradation temperature is not sufficiently occurred. On the other hand, the catalytic degradation using HZSM-5 catalyst relative to the thermal degradation shows the high conversion of pyrolysis wax oil to light hydrocarbons. This liquid product shows high gasoline range fraction as around 90% fraction and considerably high aromatic fraction in liquid product. Also, in the catalytic degradation the experimental variable such as catalyst amount and reaction temperature was studied.

• 한국응용과학기술학회지
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• 제33권3호
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• pp.492-497
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• 2016

The intermediate product resulting from the radical degradation experiment of PCE and the atomic charge gained through Gaussian03W were compared against each other. The result was that the ratio of PCE radical degradation was almost 98% or higher after the 9 hr point in reaction time. The reaction speed constant was $0.16hr^{-1}$ and it followed the first reaction. We could see that at each location of the PCE molecule, dechlorination happened at a point where the negative atomic charge was the greatest. Moreover, the intermediate product of PCE radical degradation that was confirmed in the experiment and literature coincided exactly with the intermediate product in the atomic charge calculation. Therefore, when the atomic charge is calculated, the radical degradation pathway of the organic chlorine compound could be forecast.

• 품질경영학회지
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• 제32권1호
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• pp.113-129
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• 2004

The reliability of the product can be improved by making the product less sensitive to noises. Especially, it Is important to make products robust against various noise factors encountered in production and field environments. In this paper, the phenomenon of degradation assumes a simple random coefficient degradation model to present analysis procedures of degradation data for robust experimental design. To alleviate weak points of previous studies, such as Taguchi's, Wasserman's, and pseudo failure time methods, novel techniques for analysis of degradation data using the cross array that regards amount of degradation as a dynamic characteristic for time are proposed. Analysis approach for degradation data using robust experimental design are classified by assumptions on parametric or nonparametric degradation rate(or slope). Also, a simulation study demonstrates the superiority of proposed methods over some previous works.

• 한국환경보건학회지
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• 제30권2호
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• pp.79-83
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• 2004

The oxidative degradation of BPA with laccase from Trametes versiclor was conducted in a closed, temperature controlled system containing acetate buffer for pH control. The effects of medium pH, buffer concentration, temperature and mediator on degradation of BPA were investigated. The inactivation of the enzyme by temperature and reaction product was also studied. The optimal pH for BPA degradation showed about 5. Buffer concentration did not affect BPA degradation. On the other hand, the enzyme stability was higher at low concentration buffer(25 mM). Temperature rise increased the degradation rate of BPA up to 45$^{\circ}C$. The valuable mediator of laccase for BPA was ABTS. Elevated temperature and reaction product irreversibly inactivated the enzyme.

• 한국식품위생안전성학회지
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• 제19권2호
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• pp.97-103
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• 2004

Piperophos에 대한 광분해 실험을 수행하여 속도상수와 분해생성물을 측정하였다. 햇빛을 이용한 광분해 실험은 2003년 10월 3일부터 10월 22일 까지 하였으며 상당기간 동안 농약이 햇빛에 안정함을 확인할 수 있었고, humic acid의 광관여 효과가 없음을 알 수 있었다. 자외선을 이용한 광분해 실험에서 piperophos는 자외선을 단독 조사하였을 때 자외선의 세기가 클수록 상대적으로 빠르게 분해되었으며, 광분해 촉매제인 TiO$_2$를 첨가하였을 경우에는 첨가하지 않고 자외선만 조사한 경우보다 상대적으로 느리게 분해되었다. 또, TiO$_2$의 양을 증가시켜도 별 차이가 없었다. 광분해에 의한 분해산물을 확인하고자 UMS분석을 한 결과 piperophos의 분해생성물은 m/z=166의 O,O-dipropyl phosphorodithioate로 추정된다.

• 한국토양비료학회지
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• 제45권5호
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• pp.810-816
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• 2012

현행 살처분 가축사체의 처리방안 중 하나인 랜더링 처리방법을 사용하여 나온 부산물을 액비화 시키기 위해 산 및 알칼리 분해제를 사용하여 액화시켰으며, 분해제별 주입량 및 처리시간에 따른 랜더링 부산물의 분해율과 분해속도를 조사하였다. 산 및 알칼리 분해제별 주입량 및 처리시간에 따른 랜더링 부산물의 잔존량을 조사한 결과 분해제 중 가장 높은 잔존량을 나타낸 것은 $HNO_3$으로 다른 분해제는 10분이 경과한 후 랜더링 부산물의 잔존량이 대부분 50% 이하로 나타났다. 랜더링 부산물의 분해속도 K ($hr^{-1}$)는 KOH의 경우 랜더링 부산물 무게 대비 25% > 30% > 20% > 15% > 10%순으로 25%를 넣어줬을 때 가장 빨리 분해가 되었다. $H_2SO_4$의 경우 랜더링 부산물 무게 대비 30% > 25% > 20% > 15% > 10%순으로 넣었을 때 빨리 분해되었으며, NaOH도 이와 비슷한 경향이었다. 분해제별 랜더링 부산물의 분해율은 $HNO_3$의 경우에는 순도가 약 61% 정도로 다른 분해제들보다 낮아 분해율이 현저히 떨어졌으며, KOH, NaOH 및 $H_2SO_4$의 경우에는 랜더링 부산물을 25%와 30%를 넣었을 때 큰 차이가 없어 경제성 및 효율성을 고려하였을 때 분해제를 랜더링 부산물의 무게 대비 25%를 넣었을 경우가 가장 적합하다고 판단된다.

• 산업경영시스템학회지
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• 제38권4호
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• pp.142-148
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• 2015

Due to advancements in technology and manufacturing capability, it is not uncommon that life tests yield no or few failures at low stress levels. In these situations it is difficult to analyse lifetime data and make meaningful inferences about product or system reliability. For some products or systems whose performance characteristics degrade over time, a failure is said to have occurred when a performance characteristic crosses a critical threshold. The measurements of the degradation characteristic contain much useful and credible information about product or system reliability. Degradation measurements of the performance characteristics of an unfailed unit at different times can directly relate reliability measures to physical characteristics. Reliability prediction based on physical performance measures can be an efficient and alternative method to estimate for some highly reliable parts or systems. If the degradation process and the distance between the last measurement and a specified threshold can be established, the remaining useful life is predicted in advance. In turn, this prediction leads to just in time maintenance decision to protect systems. In this paper, we describe techniques for mapping product or system which has degrading performance parameter to the associated classical reliability measures in the performance domain. This paper described a general modeling and analysis procedure for reliability prediction based on one dominant degradation performance characteristic considering pseudo degradation performance life trend model. This pseudo degradation trend model is based on probability modeling of a failure mechanism degradation trend and comparison of a projected distribution to pre-defined critical soft failure point in time or cycle.

• 청정기술
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• 제15권3호
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• pp.186-193
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• 2009

본 연구에서는 상용운전 중에 있는 반연속식 로터리 킬른형 열분해반응기에 지자체에서 발생되는 필름형 혼합 폐플라스틱을 투입한 후 열분해하여 얻은 저급의 열분해유를 세 형태의 반응온도 프로그램에서 분해반응시키고, 여기에서 얻어지는 생성유의 특성을 논의하였다. 원료인 저급 열분해유의 특성은 원소분석 및 발열량 분석, SIMDIST 분석으로 확인하였고, 각 반응온도 프로그램에 따른 분해반응 결과는 각 성분의 수율분포, 액상 생성물의 누적수율과 생성비 등으로 논의하였다. 연구결과는 한 단계 반응온도 프로그램에 비해 다단계 반응온도 프로그램의 경우가 원하는 생성물인 오일수율이 높았고, 상대적으로 잔류물의 수율은 낮게 나타났다. 연속적인 열분해반응에서 반응온도 프로그램은 생성물의 수율분포 등 생성유 특성에 많은 영향을 주었다.