• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.2
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• pp.326-340
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• 2017

This study explores the daily life of Korean designers in New York. We use in-depth interviews within the daily lives of participants to first reveal the time structure and meaning of everyday life. In this everyday time frame, this study reveals the content and meaning of life in New York, which is especially useful for fashion majors. Participants were 11 single Korean women around 30 years old working as designers in New York. Data was collected from Manhattan, New York, from November 2013 to February 2014 through the use of in-depth interviews and participant observation. Data collected daily life information on time usage, money, and energy that is first summarized into 229 meaning units. In the following, 55 central meanings were derived from stories common to behaviors for study participants and 19 subcategories were compressed into academic language. Finally, the generalized categories are divided into six categories of study life, work life, future life, family life, leisure life and fashion life. As a result of the first study, the daily time structure consisted of customary public time and personal repeat time. Second, the customary public time categories included the studying for 'Beginning to jump again to the best', 'Now working as a designer in New York', and future life expecting 'Future growing as a career woman'. Repeated personal time categories include family life: 'A single life of a lonely and poor gentile', leisure life: 'Healing life that is supported by abundant advanced culture', and fashion life: 'New York fashion life coexist with harmony'. Third, work was the center of everyday life for study participants versus fashion and leisure that were central to everyday life when not working.

• Journal of Applied Reliability
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• v.3 no.2
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• pp.93-101
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• 2003

Life time data analysis requires some time-to-failure data to an extent. Some life tests result in few or no failure. In such cases, it is difficult to access reliability with traditional life tests that record only time to failure. Furthermore, with short product development time, reliability tests must be conducted with severe time constraints. For some devices, it is possible to obtain degradation measurements over time, and these measurements may contain useful information about product reliability. This article describes degradation reliability analysis methods to do inferences and predictions about a failure-time distribution by using software. In addition, the possibility of extension to CBM (Condition Based Maintenance) is suggested as an example of applied degradation data analysis.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.4
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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.

• Korean Journal of Human Ecology
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• v.12 no.5
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• pp.605-618
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• 2003

The purpose of this study was to develop the household analysis and diagnosis program for the enhancement of family welfare focusing on the household of middle-aged full-time housewives. From the review of related literatures, the following areas of total family life were selected ; household management, time use, housing, household materials, finance, communication and decision making. Considering that the program subjects were middle-aged full-time housewives, the preparation for elderly life and the identity as housewife, one of the healthy family members, are appended. The progresses for the development of household analysis and diagnosis program were as follows: 1. to select the useful area of family life, 2. to make the indicators which explain the status of family life, and 3. to decide the scales for the diagnosis. This program has various uses such as the development of self-evaluation program, program for various family life course. Through this program the strength and weakness of family life can be found and the planning for the enforcement of family life can be practiced.

• Journal of Korean Society for Quality Management
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• v.32 no.4
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• pp.242-251
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• 2004

Several statistical methods are introduced 1=o analyze the accelerated failure time data. Most frequently used method is the log-linear approach with parametric assumption. Since the accelerated failure time experiments are exposed to many environmental restrictions, parametric log-linear relationship might not be working properly to analyze the resulting data. The models proposed by Buckley and James(1979) and Stute(1993) could be useful in the situation where parametric log-linear method could not be applicable. Those methods are introduced in accelerated experimental situation under the thermal acceleration and discussed through an illustrated example.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.47-51
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• 2007

The present paper reports the life time prediction of Acrylonitrile-Butadiene rubber (NBR) fuel cell gasket materials as a function of operational variables like acid concentration, ageing time and temperature. Both material and accelerated acid-heat aging tests were carried out to predict the useful life of the NBR rubber gasket for use as a fuel cell stack. The acid ageing of the gasket compounds has been investigated at 120, 140 and $160^{\circ}C$, with aging times from 3 to 600 h and increasing acid ($H_2SO_4$) concentrations of 5, 6, 7 and 10 vol%. Material characteristics the gas compound such as cross-link density, tensile strength and elongation at break were studied. The hardness of the NBR rubber was found to decrease with decreasing acid concentration at both 120 and $140^{\circ}C$, but at $160^{\circ}C$ interestingly the hardness of the NBR rubber increased abruptly in a very short time at different acid concentrations. The tensile strength and elongation at break were found to decrease with increase in both the acid concentrate ion & temperature. The life time of the compounds were evaluated using the Arrhenius equation.

• Computers and Concrete
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• v.25 no.2
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• pp.167-179
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• 2020

Optimal design of structures against earthquake loads is often limited to reduce initial construction costs, while the cost induced to structures during their useful life may be several times greater than the initial costs. Therefore, it is necessary to consider the indirect costs due to earthquakes in the design process. In this research, an integrated methodology for calculating life cycle cost (LCC) of moment-resisting concrete frames is presented. Increasing seismic safety of structures and reducing human casualties can play an important role in determining the optimal design. Costs incurred for structures are added to the costs of construction, including the costs of reconstruction, financial losses due to the time spent on reconstruction, interruption in building functionality, the value of people's life or disability, and content loss are a major part of the future costs. In this research, fifty years of useful life of structures from the beginning of the construction is considered as the life cycle. These costs should be considered as factors of calculating indirect costs of a structure. The results of this work represent the life cycle cost of a 4 story, 7 story, and 10 story moment-resisting concrete frame by details. This methodology is developed based on the economic conditions of Iran in 2016 and for the case of Tehran city.

• Journal of Family Resource Management and Policy Review
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• v.4 no.2
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• pp.57-73
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• 2000

The Purpose of this study is to scrutinize the time structure and time use pattern of North Korean and to identify the differences of time use patterns between South and North Korean Societies. To carry out this Purpose in-depth interviews with ten people who escaped from North Korea after 1990 and empirical survey with 158 subjects were conducted. The findings are as follows. The characteristics of time life of North Korean are uniform time use pattern in tightly scheduled daily life and shortage of disposable time and constraint of free time due to job related labor, extra job activities including learning, meeting and evaluation, and labor mobilization. Women are faced with heavy burden of doing job and housework in the continuing patriarchal way of thinking and in the circumstances of poor housing environment. In North, Leisure time is constraint and leisure facilities are poor and the concept of leisure is totally different as that of South. North Korean think leisure as connecting with work and education and as public sphere, not private sphere. I this context leisure is considered as means for the strengthening of the communist society. Differences in the perception of time life through defectors are as follows. In South, there are plenty of leisure time and man can control his own time. Man spend his free time for various activities, especially for cultural activities such as sports, recreation, eating out with families and spend time till late in the outdoors. This study revealed differences in many aspects of time life between South and North Korean societies. These results will provide useful informations for the overcome of differences of cultural life of South and North Korean societies and accomplishment of the real integration of two societies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2401-2406
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• 2015

Pipelines are used by large heavy industries to deliver various types of fluids. Since this is important to maintain the performance of large systems, it is necessary to accurately predict remaining life of the corroded pipeline. However, predicting the remaining life is difficult due to uncertainties in the associated variables, such as geometries, material properties, corrosion rate, etc. In this paper, a statistical method for predicting corrosion remaining life is proposed using Bayesian inference. To accomplish this, pipeline failure probability was calculated using prior information about pipeline failure pressure according to elapsed time, and the given experimental data based on Bayes' rule. The corrosion remaining life was calculated as the elapsed time with 10 % failure probability. Using 10 and 50 samples generated from random variables affecting the corrosion of the pipe, the pipeline failure probability was estimated, after which the estimated remaining useful life was compared with the assumed true remaining useful life.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.2
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• pp.48-55
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• 2020

Recently, a study of prognosis and health management (PHM) was conducted to diagnose failure and predict the life of air craft engine parts using sensor data. PHM is a framework that provides individualized solutions for managing system health. This study predicted the remaining useful life (RUL) of aeroengine using degradation data collected by sensors provided by the IEEE 2008 PHM Conference Challenge. There are 218 engine sensor data that has initial wear and production deviations. It was difficult to determine the characteristics of the engine parts since the system and domain-specific information was not provided. Each engine has a different cycle, making it difficult to use time series models. Therefore, this analysis was performed using machine learning algorithms rather than statistical time series models. The machine learning algorithms used were a random forest, gradient boost tree analysis and XG boost. A sliding window was applied to develop RUL predictions. We compared model performance before and after applying the sliding window, and proposed a data preprocessing method to develop RUL predictions. The model was evaluated by R-square scores and root mean squares error (RMSE). It was shown that the XG boost model of the random split method using the sliding window preprocessing approach has the best predictive performance.