• 가정과삶의질연구
• /
• 제7권1호
• /
• pp.1-14
• /
• 1989

The purpose of this study was to identify the problems in the consumption life of household over the family life cycle so that they would support to select the consumer education subjects and the establish the long-term household plan. For these purposes, a survey was conducted using questionnaire. The data used in this study included 562 homemakers living in Seoul. Statistics used for data analysis were frequency distribution, Mean, Percentile, One-way Anova, Scheffie-test, Multiple Classification Analysis. Major findings were as follows; 1) In the level of the problems in the consumption life of household, housing problem, durable goods problem, healthy-medical problem and child education problem area were in the low level. Leisure problem and properties management problem area were in the high level. 2) The problems in the consumption life of household differed significantly over the family life cycle. 3) When controlling family monthly income and education level of husband was compared with not-controlling them, the influences of family life cycle on the problems in the consumption life were as follows. (1)At housing problem area, the effect of the FLC was higher in controlling them than not-controlling them. (2) At other problems the effects of the FLC was lower or same in controlling them than not-controlling them.

• Journal of Computing Science and Engineering
• /
• 제7권2호
• /
• pp.81-88
• /
• 2013

In cognitive radio or dynamic spectrum access networks, a rendezvous represents meeting two or more users on a common channel, and negotiating to establish data communication. The rendezvous problem is one of the most challenging tasks in cognitive radio ad hoc networks. Generally, this problem is simplified by using two well-known mechanisms: the first uses a predefined common control channel, while the second employs a channel hopping procedure. Yet, these two mechanisms form a life cycle, when they simplify the rendezvous problem in cognitive radio networks. The main purpose of this paper is to point out how and why this cycle forms.

• 성인간호학회지
• /
• 제26권2호
• /
• pp.139-148
• /
• 2014

Purpose: This study was aimed to investigate the factors influencing problem drinking of male drinkers above 19 years old according to the life cycle. Methods: The study subjects consisted of a representative community sample of 2,229 male drinkers aged 19 and older from the 2011 Korean National Health and Nutrition Examination Survey. The collected data were analyzed using descriptive statistics, Rao-Scott $x^2$-test, simple and multiple logistic regressions. Results: The problem drinking rates were 38.7% in adolescence, 44.5% in middle age, and 23.9% in senescence. In adolescence, the predictors of problem drinking included occupation, stress recognition, and smoking. In middle age, the predictors of problem drinking were education level, depression, and smoking. In senescence, the predictors of problem drinking were not identified in this study. Conclusion: The findings of this study suggested that the factors influencing problem drinking of male drinkers were different according to life cycle. Thus different intervention methods should be developed for each age group in order to intervene the problem drinking.

• 여성건강간호학회지
• /
• 제21권1호
• /
• pp.43-54
• /
• 2015

Purpose: This study was conducted to identify the problem of bone health and potential influencing factors of bone mineral density (BMD) for women across the life cycle of menopause. Methods: Complex sampling design data analysis was performed on the fifth Korea National Health and Nutrition Examination Survey 2010 in order to identify the problems with bone health, BMD and its influencing factors in 3,499 women who answered the menopausal status. Women's life cycle was categorized by premenopausal, postmenopausal, and elderly. Results: 35.1% of premenopausal women, 73.3% of postmenopausal women, and 96.0% of elderly women had problems with bone health that were related to low BMD. Influencing factors of BMD were residential area, alcohol drinking, and body mass index (BMI) for premenopausal women; age, residential area, education, marital status, income, and BMI for postmenopausal women; and age, education, and BMI for elderly women. Conclusion: Problems with bone health required to be considered as a major health problem in all women regardless their life cycle. Interventions to maximize BMD need to be developed by considering its influencingfactors across the women's life cycle.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
• /
• pp.151-158
• /
• 1998

This paper presents an optimal decision model for minimizing the life-cycle cost of steel box girder bridges. The point is that it takes into account service life process as a whole, and the life-cycle costs include initial (design, testing, and construction) costs, maintenance costs and expected failure costs. The problem is formulated as that of minimization of expected total life-cycle cost with respect to the design variables. The optimal solution identifies those values of the decision variables that result in minimum expected total cost. The performance constraints in the form of flexural failure and shear failure are those specified in the design code. Based on extensive numerical investigations, it may be positively stated that the optimum design of steel box girder bridges based on life-cycle cost approach proposed in this study provides a lot more rational and economical design, and thus the proposed approach will propose the development of new concepts and design methodologies that may have important implications in the next generation performance-based design codes and standards.

• 가정과삶의질연구
• /
• 제16권3호
• /
• pp.111-122
• /
• 1998

This study analyzed the copmposition of household portfolio over the family life cycle using a survey dta of 1996 Korea Household Panel Study. The finindings showed that over th family life cycle households diversified their portfolio to meet their financial needs. In the aged stage however households were more likely to have liquidity problem than the households in th other stages due to the estate concentrated portfoplio composition.

• 한국산학기술학회논문지
• /
• 제17권4호
• /
• pp.19-25
• /
• 2016

사회기반시설물을 포함한 구조물은 수명유지 또는 연장을 위하여 적절한 점검과 유지보수가 필수적이다. 이러한 점검과 유지보수는 일반적으로 생애주기비용 평가를 통해 관련 계획이 수립된다. 본 논문에서는 구조물의 생애주기비용과 그 사용으로 인해 발생되는 이익을 고려하는 확률론적 비용-이익분석과 이를 통한 구조물 최적수명 결정 방법을 다루고자 한다. 생애주기비용은 구조물 초기 제작/건설비용, 유지보수 비용과 구조물 파괴로 인한 예상손실을 고려하게 된다. 일반적으로 구조물의 수명연장은 생애주기비용의 증가를 유발하나 사용기간 증가로 인해 발생되는 이익 또한 증가하여, 이를 최적화하는 수명관리에 관심을 가질 필요가 있다. 생애주기 평가에 있어서 유지보수 적용이 구조성능, 구조물 파괴확률 그리고 수명에 미치는 영향을 확률론적 방법을 적용하여 평가하며, 이를 통해 생애주기비용과 이익의 차이를 목적함수로 구성하게 된다. 이 목적함수가 최대가 되는 지점이 설계변수인 구조물 최적수명이 되는데, 최적화문제 구성에 있어서 제한조건의 변화에 따라 유지보수 계획수립도 가능하다. 본 논문에서 다루어지는 구조물 수명관리 최적화기법이 안전성과 효율성을 동시에 고려하는 사회기반시설물 수명관리에 기여할 것으로 기대한다.

• 소성∙가공
• /
• 제30권4호
• /
• pp.172-178
• /
• 2021

The cold forging process induces material deformation in an enclosed space, generating a very high forging load. Therefore, it is mainly designed as a multi-stage process, and fatigue failure occurs in forging die due to cyclic load. Studies have been conducted previously to quantitatively predict the fatigue limit of cold forging dies, however, there was a limit to field application due to the large error range and the need for expert intervention. To solve this problem, we conducted a study on the introduction of a real-time forging load measurement technology and an automated system for quantitative prediction of die life cycle. As a result, it was possible to reduce the error range of the quantitative prediction of die life cycle to within ±7%, and it became possible to use the die life cycle calculation algorithm into an automated system.

• 한국철도학회논문집
• /
• 제12권6호
• /
• pp.1076-1080
• /
• 2009

수명주기비용(Life Cycle Cost, LCC) 분석이란 분석 대상의 수명주기 전 기간에 걸친 총 원가산정을 통하여 해당 시스템을 평가하는 것이다. 철도시스템은 급전, 기계, 전기신호 등의 분야가 결합된 시스템으로 대규모 자본을 효율적으로 이용해야만 하는 문제를 안고 있다. 특히, 자기부상열차 시스템은 고도의 기술력이 필요하며 현재 국내에서 개발 단계에 있는 시스템으로, 비용 관련 연구가 더욱 필요한 실정이다. 따라서 국외의 철도시스템 및 자기부상열차 시스템에 대한 수명주기비용 연구 동향을 바탕으로 하여 국내의 자기부상열차 시스템에 적용할 수 있는 수명주기비용에 관한 모델을 제안하고자 한다.

• Smart Structures and Systems
• /
• 제30권6호
• /
• pp.571-582
• /
• 2022

Optimal life-cycle management is a challenging issue for deteriorating regional bridges. Due to the complexity of regional bridge structural conditions and a large number of inspection and maintenance actions, decision-makers generally choose traditional passive management strategies. They are less efficiency and cost-effectiveness. This paper suggests a deep reinforcement learning framework employing double-deep Q-networks (DDQNs) to improve the life-cycle management of deteriorating regional bridges to tackle these problems. It could produce optimal maintenance plans considering restrictions to maximize maintenance cost-effectiveness to the greatest extent possible. DDQNs method could handle the problem of the overestimation of Q-values in the Nature DQNs. This study also identifies regional bridge deterioration characteristics and the consequence of scheduled maintenance from years of inspection data. To validate the proposed method, a case study containing hundreds of bridges is used to develop optimal life-cycle management strategies. The optimization solutions recommend fewer replacement actions and prefer preventative repair actions when bridges are damaged or are expected to be damaged. By employing the optimal life-cycle regional maintenance strategies, the conditions of bridges can be controlled to a good level. Compared to the nature DQNs, DDQNs offer an optimized scheme containing fewer low-condition bridges and a more costeffective life-cycle management plan.