• Journal of Korean Society for Quality Management
• /
• v.24 no.4
• /
• pp.14-28
• /
• 1996

We consider optimal designs of partially accelerated life testing which is deviced for parallel systems with the considerably long life time. In partially step-stress life testing, test items are first run simultaneously at use condition for a specified time, and the surviving items are then run at accelerated condition until a predetermined censoring time. In partially constant-stress life testing, test items are run at either use or accelerated condition only until a specified censoring time. The optimal criterion for each test is to minimize either the generalized asymptotic variance of maximum likelihood(ML) estimators of the hazard rates at use condition and the acceleration factors or the asymptotic variance of the ML estimators of the acceleration factors.

• Journal of the Korean housing association
• /
• v.14 no.1
• /
• pp.1-10
• /
• 2003

The purpose of this study is to analyze patterns of space use and housing preferences to be used in the housing plan for students. Data was collected through questionnaire surveys from local university students living apart from their family. We collected 272 samples and analyzed them using SPSSwin program. The results are as follows; 1) The average hours of staying at the housing for student are 5 hours and 30 minutes(except sleeping time). Most of the time was used for ‘hobby’ and ‘study\ulcorner computer works’. The most of the students had ‘a meal per day’ at their housing. 2) The most preferred housing type by the students is ‘studio apartment’ and the next preferred is ‘apartment’. The highly demanded facility is ‘laundry’ and the next comes ‘kitchen’. 3) Those who spend more time in their housing than average show higher demand in ‘kitchen’ and ‘balcony’. Those who spend less time in their housing show higher demand in ‘storage’.

• Journal of the Korean Home Economics Association
• /
• v.36 no.4
• /
• pp.35-48
• /
• 1998

The imputation of monetary value of women's contribution to the informal economy for inclusion in satellite accounts to the formal System of National Accounts has been attempted along many methods. This is bases on official laborforce statistics and time-use survey. In this statistical system, household work is not an economic activity(or productive labor). Also, the clssification of activities involved in household work is different from that of sampling survey relating evaluation. The measurement of women's unpaid work is one of the important tasks for the improvement of women's status and the establishment of a development policy. To measure unpaid work in the economic terms, we should take following measures; 1) develop satellite or other official accouts to measure unpaid work outside national accounts. 2) conduct a nation-wide time-use survey to measure the unpaid work. 3) develp a proper classificaition of activities for time-use statistics. 4) reexamine the minimum time criterion. 5) determine a proper method of valuing along the law system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.10a
• /
• pp.510-513
• /
• 2001

OTP(One-time Password) had been used much by method to do user certification so far. Because aspect that user certification that use OTP is efficient and economical fairly is much, it is one of method that can use easily. This treatise would apply OTP in message authentication and wishes to show that OTP is available for inter-authentication. First, examine about OTP's characteristic and overview in introduction, and explain about user certification method to use OTP in main discourse and method of message certification. And finally. wish to examine how OTP offers inter-authentication function.

• Nuclear Engineering and Technology
• /
• v.55 no.11
• /
• pp.4077-4082
• /
• 2023

Large areas must be rapidly screened to monitor radiation in marine environments. For this purpose, this study developed a mobile real-time gamma-ray measurement system for shipboard use and evaluated its performance. The system was developed to measure engine or generator cooling water by installing a canister inside the ship. The minimum detectable activity of the system is about 0.8 Bq/L for a 60 s measurement period, and real-time data transmission and remote control are possible. The system was tested in the field and is currently being installed and operated on ships in service. Such a ship-based real-time gamma-radiation measurement system is suitable for a wide range of marine radiation surveillance applications and is expected to be rapidly deployed.

• Survey Research
• /
• v.10 no.2
• /
• pp.1-21
• /
• 2009

The purpose of this study is to compare the estimates of housework time by gender using two representative methods of time use study: Time Diary and Stylized Survey Questionnaire. Our analysis is based on the data from the Lifetime Use Survey(2004), which used time-diary questions, and the Korean Labor & Income Panel Study(KLIPS 2004), which used stylized questions on housework hours. The results show that men over-report their housework time in the stylized time use questions. In contrast, women under-report their housework time, which is unusual in the previous studies on response errors and reporting gap. Subgroup analysis shows that widowed/divorced men tend to over-report their contribution to housework more than other groups whereas among women, groups burdened with employed work, caring and housework underestimate their housework time. This reporting gap is explained by gendered norm and perception of time pressure. The theory to explain under-reporting of the housework time has been undeveloped in the previous studies. Our study suggests that perceptions of time pressure be an important factor to explain women's reporting gap of housework estimates.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.17 no.1
• /
• pp.1-16
• /
• 2018

Changes in the life style might vary trip purposes, ultimately leading to the change in the travel behavior. Therefore, this study analyzed the factors affecting travel time change by using the time use survey data in Seoul, surveyed by the Statistics Korea in 1999~2014. We developed multiple linear regression models for travel time, considering individual, household and time-related variables as independent variables. The models were separately estimated weekday and weekend. the model results show that the household, individual, and time related variables have an significant effect on the travel time. In addition, travel time is more influenced by individual characteristics thn household ones. Each activity time positively affects the travel time, indicating that travel is derived demand. The variable that have the greatest influence on the travel time is the activity time for leisure.

• Journal of the Korean housing association
• /
• v.21 no.5
• /
• pp.125-135
• /
• 2010

As the educational environment is qualitatively improved by revision of the school curriculum, local residents become increasingly interested in sharing the educational environment through the mixed-use of school facilities. The purpose of this study was to obtain a better understanding of the use and need for school facilities. This study involved a literature review and a survey of local residents who have used school facilities. The results are as follows: (1) sports and learning facilities were the most used of five different types of school facilities, (2) school facilities were mainly used in the evenings (18:00~22:00 hrs), but the respondents differed in terms of time of use according to gender, age and work hours, (3) the result showed high needs for all types of facility and needs for sports facilities among them were the highest, and (4) preferred time of use was varied according to the type of facility and the residents' characteristics. In conclusion, this study explored various directions for the mixed-use of school facilities by analyzing local residents' current use and their needs for further use of these facilities, taking into account the different characteristics of the users.

• Journal of Hospice and Palliative Care
• /
• v.24 no.3
• /
• pp.184-193
• /
• 2021

Purpose: This study attempted to develop clinical guidelines to help patients use hospice and palliative care (HPC) at an appropriate time after writing physician orders for life-sustaining treatment (POLST) by identifying the characteristics of HPC use of patients with terminal cancer. Methods: This retrospective study was conducted to understand the characteristics of HPC use of patients with terminal cancer through decision tree analysis. The participants were 394 terminal cancer patients who were hospitalized at a cancer-specialized hospital in Seoul, South Korea and wrote POLST from January 1, 2019 to March 31, 2021. Results: The predictive model for the characteristics of HPC use showed three main nodes (living together, pain control, and period to death after writing POLST). The decision tree analysis of HPC use by terminal cancer patients showed that the most likely group to use HPC use was terminal cancer patients who had a cohabitant, received pain control, and died 2 months or more after writing a POLST. The probability of HPC usage rate in this group was 87.5%. The next most likely group to use HPC had a cohabitant and received pain control; 64.8% of this group used HPC. Finally, 55.1% of participants who had a cohabitant used HPC, which was a significantly higher proportion than that of participants who did not have a cohabitant (1.7%). Conclusion: This study provides meaningful clinical evidence to help make decisions on HPC use more easily at an appropriate time.

• Proceedings of the Safety Management and Science Conference
• /
• 2004.11a
• /
• pp.229-235
• /
• 2004

This paper treats accelerated life tests for automotive connector. The contact resistance of connector is explained by some factors; the use time(calender time, real cycle), stresses and loads adapted in auto test. The relationships between contact resistance and some factors are compared and analyzed by regression models in various test conditions; field use-environment, manufacturer's test environment, and accelerated test condition. The consistency between of manufacturer's test and field test is examined. Finally, the future study on accelerated test for automotive connector is presented.