• Journal of Korean Society of Water and Wastewater
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• v.9 no.2
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• pp.118-126
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• 1995

The variation of the urban water demand and the amount of water in the distribution reservoir was studied with time for a day. The city of Kwangju in Korea was selected as a study area. The population of Kwangju in the end of 1993 was more than one million and two hundred thousand peoples. The average of daily water use in 1993 was about three hundred and fifty thousand tons a day. One day was devided into 12 divisions with a 2 hour increment. The water use demand related to the amount of water in the distribution reservoir was observed for the given time interval of a day. The water use index was defind in percentage that indicates the ratio of the amount of water use for a time interval to the amount of water use for a day. The water use index with consideration of the water stored in the reservoir was found to be useful to manage and to operate the water supply systems in real time.

• Journal of Labour Economics
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• v.37 no.2
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• pp.49-78
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• 2014

This paper examines the impacts of introducing Five-day school week in South Korean on adolescents' time use. Exploiting the exogenous variation in the adolescents' time at school on Saturday, I estimate the causal effect of change of adolescents' discretion time on their time use. The main findings are as follows. The introduction of the five day school week increased the adolescents' discretion time and their time spent on sleeping, passive leisure(mainly watching television). A one-minute decrease in the adolescents' time at school increase their sleeping time by 0.46 minute and passive leisure time by 0.26 minute.

• Journal of Family Resource Management and Policy Review
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• v.15 no.2
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• pp.129-146
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• 2011

This study is daily life research which aims to explore people's daily lives using a time dairy survey. The purpose of this study is to develop a typology of early, elderly over 55-year-olds using the 2009 Korean Time Use Survey. The results suggest that each man and woman can be classified according to three dimensions which are work time, housework time, and leisure time. Four groups of men are described: the work and leisure balanced type, the work-oriented type, the leisure-oriented type, and the leisure with housework type. Four groups of women are illustrated: the work-oriented type, the leisure-oriented type, the housework-oriented type, and the passive type. The eight groups are characterized by age, education, income, spouse, gender role, lack of time, and satisfaction of time use.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.77-82
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• 2020

IoT devices frequently require input resources to communicate with various sensors or IoT platforms. IoT device wastes a lot of time as idle time or waiting time to check the data of the input resource and use the input resource. In addition, IoT devices use various input resources. We compares and analyzes input idle time and input waiting time generated from hardware serial input resource, software serial input resource, digital port input resource, and analog port input resource using Arduino widely used as IoT device. In order to design the IoT device framework, it is necessary to understand the characteristics of input resources and to design them to minimize unnecessary input idle time and input waiting time. The analog input wait time has a much larger input wait time than the digital input wait time, so it must be designed to receive analog information periodically at the appropriate timing. The characteristics of the input resources analyzed in this way help to design an efficient IoT device.

• Survey Research
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• v.12 no.2
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• pp.145-157
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• 2011

There are limitations as to how internet surveys can be used. Applying various weighting procedures has not always resulted in error reduction. A good reference survey would increase the effects of the weighting method, but it is very difficult to get a reference survey for non-demographic weighting variables, which restricts the use of internet surveys. We hypothesized that time use variables could be employed as weighting variables. The time use survey is conducted regularly by KOSTAT and includes various time-related variables. We tested our hypothesis using the 2009 survey results, which had been gathered by KOSTAT in 2009. When we applied weighting variables which were based on the 2004 time use survey results to the online version of the 2009 KOSTAT social survey, the gap between the online and off-line versions was slightly reduced. This result shows that we could use time use survey results to develop a better weighting scheme.

• Journal of Korean Society for Quality Management
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• v.32 no.3
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• pp.62-67
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• 2004

This paper presents and compares two block replacement policies under random use durations. The units are put in service altogether and then idle for some time. The time durations during which units are put in service are random variables. Two block replacement policies, called N-policy and T-policy, are presented. Under N-policy, units are replaced altogether after the Nth use. Under T-policy, units are replaced altogether at the end of the use after cumulative use time T elapses. The failures during use durations are replaced by new ones individually. The cost rate expressions under the policies are derived for exponential use durations. Numerical examples are presented to compare the performances of the two policies.

• Human Ecology Research
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• v.55 no.5
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• pp.451-463
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• 2017

Recently, increasing one-person households, especially in the young generation, is one of the most important issues reflecting changes in the Korean family and society. The purpose of this study is to examine gender differences in life time use of one-person households aged 25 to 39, comparing with husband-wife couples of the same ages, and to investigate the determinants of subjective time poverty. Data are from the 2014 Life Time Survey by Statistics Korea. The major results are as follows. First, gender differences in time use of single youths were found in home management hours on weekdays. Female one-person householders spent more time in home management than their male counterparts, while male one-person householders spent more time in home management than young husband-wife groups. In addition, a much larger gender difference was found between young husbands and wives. Second, different effects on the subjective time poverty were found in both the groups. Based on these results, the implications for several specialized education and social programs for male and female one-person householders used in the local healthy families support centers are provided.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3112-3127
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• 2018

Since time series clustering is performed without prior information, it is used for exploratory data analysis. In particular, clusters of time series with similar shapes can be used in various fields, such as business, medicine, finance, and communications. However, existing time series clustering algorithms have a problem in that time series with different shapes are included in the clusters. The reason for such a problem is that the existing algorithms do not consider the limitations on the size of the generated clusters, and use a dimension reduction method in which the information loss is large. In this paper, we propose a method to alleviate the disadvantages of existing methods and to find a better quality of cluster containing similarly shaped time series. In the data preprocessing step, we normalize the time series using z-transformation. Then, we use piecewise aggregate approximation (PAA) to reduce the dimension of the time series. In the clustering step, we use density-based spatial clustering of applications with noise (DBSCAN) to create a precluster. We then use a modified K-means algorithm to refine the preclusters containing differently shaped time series into subclusters containing only similarly shaped time series. In our experiments, our method showed better results than the existing method.

• Journal of the Korean Home Economics Association
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• v.35 no.6
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• pp.173-189
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• 1997

The purpose of this study was to investigate housewives'time use and satisfaction with it and analyze the factors affection these. Subjects were 222 housewives with pre-and elementary school children. The data were analyzed by mean, standard deviation, X-test, t-test, ANOVA and Duncan's multiple range test. The results of this study were as follows : 1) Housewives spent over 1/3 of time on physical care(sleeping.. etc.). 2)The use of time by housewives was mainly influenced by husband's status and children's state(age, the number of extra curricular hours, educational level) 3) The satisfaction with time use was affected by first child's age, husband's age, husband's educational level, wives's educational level, and household income.

• Journal of the Korean Home Economics Association
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• v.31 no.3
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• pp.101-112
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• 1993

The purpose of this study is to examine the real life of married women employed in a manufacturing industry by analysis patterns of their time use. Data for 172 married working women were gathered from the use of face-to-face interview method. The results were shown as follows; 1) Married female production workers spend 8 hours 44 minutes a weekday, and 10 hours 39 minutes a Sunday on physiological activities, and on socio-cultural activities 1 hour 50 minutes(weekday), 5 hours 30 minutes (sunday). 10 hours 22 minutes, 2 hours 23 minutes were consumed for the employed time compared to 3 hours 4 minutes, 5 hours 28 minutes for household labor. 2) Married working women's employed labor time is excessively too long while for leisure and house work time is too short, which means the patterns of their time use are very unbalanced type.