• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3443-3447
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• 2011

The spectroscopic behavior of catechin (5,7,3',4'-tetrahydroxyflavan-3-ol), has been studied in the presence and the absence of air using UV-vis absorption spectrophotometry and fluorescence spectroscopy. The UV-vis absorption spectrum of catechin shows a very sharp and strong absorption maximum peak at 275 nm in deaerated water. New absorption maximum peaks appeared in aerated water, as well as in basic aqueous solution, caused by the oxidation of catechin. The absorbances in the UV-vis absorption spectrum of catechin decreased when the solution was left in the dark for a long time. The fluorescence emission spectrum of catechin after a long time period differs markedly from that in freshly prepared solution; the fluorescence maxia shifted as time passes after adding catechin to the solutions. When the deaerated basic catechin solutions were left in the dark for a long time, their fluorescence quantum yields were found to be nearly zero. This suggests that the oxidized catechin molecules were seen to have slowly undergone successive chemical reactions in basic buffer solution.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.61-67
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• 2017

Research into the selection of suitable materials and the development of fast processing methods for press die manufacturing is absolutely necessary to reduce the production time and cost. In particular, knowledge of its heat properties must be considered whendeveloping a long press die. Generally, as the main component materials of press dies, Cr, W low alloy tool steel, high carbon-high chrome steel, high speed steel, etc., are used as thetooling steel for the cold die. Machine tools and wire-cut electric discharge machining are mainly used for processing the press die parts. There are many differences in the machining time and life cycle of die parts depending on the machining process. The parts produced by milling and grinding have a high manufacturing time and cost with a long life cycle, while thosemade by milling and wire-cut discharge machining have areduced manufacturing time and cost,whereastheir die life cycle is reduced. Therefore, in this study, we will discuss amethod of improving the life cycle of the die parts by using heat treatment as a processing method that reduces the manufacturing time and cost. SEM, EDS analysis and the surface roughness analysis of the surface and center of the workpiece are used for analyzing the specimens produced by three machining methods, viz. milling - grinding, milling - wire cut discharge, and milling - wire cut discharge - heat treatment. A method of making die parts having the same life cycle as those produced by milling - grinding is developed with the milling - wire cut discharge - high temperature tempering method.

• Journal of Forest and Environmental Science
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• v.28 no.4
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• pp.247-253
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• 2012

The purpose of this study was to conduct phenology monitoring of forest plant species in Mt. JuWang National Park, thereby establish long-term prediction and management system for species susceptible to climate change, and utilize the result as basic materials necessary for conservation of plant genetic resources in accordance with changes in their growth environment. Global Positioning System coordinates were marked on each indicator species and a specific number ticket was provided to each plant. Changes in their blooming time, time of blossoms falling, time of leaves bursting into life, and time of leaves turning, and time of leaves falling were recorded. Investigation was made once per week from April 10 in 2010 to November 30 in 2011 except for the time period between July and August when investigation was made biweekly. The investigated plants concerned 12 kinds-nine species of trees and three kinds of herbs. According to the result of the penology monitoring of Mt. JuWang National Park, their time of leaves bursting into life, time of leaves turning, and time of leaves falling were largely earlier in 2011 than in 2010. However, it is hard to say that it is due to the factor of climate change. Long-term collection of climate data and continuous monitoring of plant phenology are considered necessary in order to examine correlation between climate change and seasonal change patterns of plants.

• Transactions of Materials Processing
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• v.12 no.1
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• pp.18-25
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• 2003

This paper explains the process design for improving tool life in the conventional hot forging process. The thermal load and the thermal softening are happened by contact between the hotter billet and the cooler tools in hot forging process. Tool life decreases considerably due to the softening of the surface layer of a tool was caused by a high thermal load and long contact time between the tools and the billet. Also, tool life is to a large extent limited by wear, heat crack and plastic deformation in hot forging process. Above all, the main factors which affect die accuracy and tool life we wear and the plastic deformation of a tool. The newly developed techniques for predicting tool life are applied to estimate the production quantity for a spindle component and these techniques can be applied to improve the tool life in hot forging process.

• International Journal of Reliability and Applications
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• v.2 no.4
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• pp.241-251
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• 2001

In this paper, optimal bum-in time to minimize the total mean cost, which is the sum of manufacturing cost with burn-in and cumulative warranty-related cost, is obtained. When the products with cumulative pro-rata warranty have high failure rate in the early period (infant mortality period), a burn-in procedure is adopted to eliminate early product failures. After burn-in, the posterior product life distribution and the warranty-related cost are dependent on burn-in time; long burn-in period may reduce the warranty-related cost, but it increases the manufacturing cost. The paper provides a methodology to obtain total mean cost under burn-in and cumulative pro-rata warranty. Property of the optimal burn-in time is analyzed, and numerical examples and sensitivity analysis are studied.

• Journal of Families and Better Life
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• v.16 no.1
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• pp.125-139
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• 1998

This study investigates work loads and coping strategies of the married female production workers(MFPW). The data of 370 MFPW in manufacturing sector in Taegu are collected by using a questionare in August 1995 The findings of this study are as follow: 1) The results of objective work loads assessed time dairy show that the average working hours is 14.25 hours during weekdays. The respondents spend 11.5 hours and 2.75 hours on doing paid and household work respectively,. The shortage of phisiological and leisure time due to spending excessively long time on work. 2) MFPW perceive the severe subjective work loads in the areas of personal family and social life. The perceived burden from paid work itself is relatively low due to the nature of their job. 3) The coping strategies MFPW actually adopted are limited mostly to those from an individual domain such as shortening the time for sleep leisure or household labor.

• Journal of the Korean Regional Science Association
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• v.35 no.2
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• pp.59-71
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• 2019

Korea's average annual working hours are among the highest in the OECD. Such long-term work has been a factor that reduces the quality of life by discouraging workers' productivity and interrupting the compatibility of work and family, prompting the government to encourage flexible work systems, such as increasing part-time jobs, but a lack of quality part-time jobs. Part-time work enables flexible labor for workers, but at the same time, workers will involuntarily opt for part-time work as they have poor working conditions and negative social views. In this respect, the effect of the working type on an individual's life is expected to be different. In addition, for women, gender gaps exist in the labor market and the impact of part-time work on life satisfaction is expected to differ from men in terms of working and family alike. Using the data from the 2017 "Seoul Survey Urban Policy Indicator Survey", the ordered logistic regression model was used to analyze the cross-effect of working type and sex on satisfaction. The analysis of the study showed that when other factors were controlled, life satisfaction was high in the order of fulltime female, full-time male, part-time female, and part-time male. In addition, further analysis shows that the parttime female workers have the highest probability of choosing low life satisfaction, while the probability of choosing high life satisfaction is the lowest, and full-time male workers have the lowest probability of choosing low life satisfaction, while the highest probability of choosing high life satisfaction is the highest.

• Journal of the Korea Institute of Building Construction
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• v.18 no.6
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• pp.603-609
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• 2018

It has been widely-reported that the quality of life in Korea is lower than that of the economic growth. In particular, construction managers are reported to have a lower quality of life compared to people in other job types due to the specific nature of the tasks they have to carry out. These include early work attendance time and fewer holidays. In this respect, the aim of this study is to analyse construction managers' requirements on work-life balance. The results showed that the working hours of construction managers were long and their leisure hours were shorter. The requirements for work-life balance were in the order of non-working time, working time, salary, and job security. The requirements by group showed a statistically significant difference in work hours. The requirements on the shortening of work hours were highest in the group of "section chiefs and deputy heads" and lowest in the group of "department heads" and up. It is hoped that the results of this study will be used as basic data for future government-level policy making and construction companies' business directions in relation to the improvement of workers' work-life balance.

• Journal of Digital Contents Society
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• v.14 no.1
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• pp.59-64
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• 2013

In this paper, we proposed low power algorithm for a task. The task means the inside of a necessary processor and external resources to work accomplishment of a system. Each task analyzes a life time and a number of called for implement a low power circuit. First of all, reduce power consumption of a task have maximum power consumption for low power circuit implementation. Therefore, first selecting a task had maximum power consumption. The task had a maximum power consumption ranking consider a life time and a number of called for each task. While a life time of task is long, top priority ranking to decrease power consumption to the task that the number of call generates the power consumption how a disguise is large in case of a lot of task becomes. Frequency decision to have minimum power consumption, and decrease power consumption all the circuit by a change of frequency of the task which the minimum task that a wasting past record is the maximum becomes. Also, keep continuously minimum power consumption, with every effort task until last life time in opening life time, and decrease gets total power consumption. Experiments results show reduction in the power consumption by 5.43% comparing with that [7] algorithm.

• Journal of Families and Better Life
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• v.9 no.2
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• pp.171-190
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• 1991

This study focused on time use and the influencing factors of employed wives. Its aims are specified as follows.:1) to figure out the tendency of time use spent on a holiday and weekday by employed wives ; (2) to find out factors influencing the amount of time in each domain spent on each day. The samples were composed for 396 employed wives living in Seoul and Kwangju city who had the eldest child less than 18years old. were sampled based on their work kind, work status, and residential quarter. The results are as follows; 1) Employed wives spend 423 minutes a weekday, and 513 minutes a holiday on the sleep and 522 minutes(weekday ), 618 minutes (holiday) on the total Physiological time 599 minutes (weekday), 72 minutes(holiday) were devoted to the employed time. compared to 214 minutes. 395 minutes for the housework Finally 103 minutes and 349 minutes were assigned to leisure time. Compared with the research results in Japan and the United States, this shows large difference. Korean wives; work time is excessively too long while the time for leisure and psysiological time is too short, which means the life style of Korean wives ti too simple and monotonous. 2) Social demographic variables(such as work status, education, income, wive's relative income rate, family type. family number, the younger child's age, and etc. )and variables connected with employment (such as employed work time and employment motivation) significantly differentiate the time use. A wive with higher education, employment status, and income level, spends more time for the psysiological , leisure time, and manegerial housework time, while spending less time for work and physical housework.