• Computers and Concrete
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• 제22권3호
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• pp.261-267
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• 2018

Long-term deformation of a steel-reinforced concrete (SRC) column is different from that of a reinforced concrete (RC) column due to the different moisture distribution. Wide-flange steel in an SRC column obstructs diffusion and makes long-term deformation slower. Previous studies analyzed the characteristics of long-term deformation of SRC columns. In this study, an additional experiment is conducted to more precisely investigate the effect of wide-flange steel on the long-term deformation of SRC columns. Long-term deformation, especially creep of SRC columns with various types of wide-flange steel, is tested. Wide-flange steel for the experiment is made of thin acrylic panels that can block diffusion but does not have strength, because the main purpose of this study is to exclusively demonstrate the long-term deformation of concrete caused by moisture diffusion, not by the reinforcement ratio. Experimental results show that the long-term deformation of a SRC column develops slower than that in a RC column, and it is slower as the wide-flange steel hinders diffusion more. These experimental results can be used for analytical prediction of long-term deformation of various SRC columns. An example of the analytical prediction is provided. According to the experimental and analytical results, it is clear that a new prediction model for long-term deformation of SRC columns should be developed in further studies.

• 한국정보시스템학회지:정보시스템연구
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• 제16권2호
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• pp.123-144
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• 2007

As the interest in the business-to-business electronic commerce is increasing, many companies are participating in the business-to-business e-marketplaces. As a result, it is important to develop understanding of behaviors of firms that use these e-marketplaces. For this purpose, e-marketplace usage company trust is proposed to affect commitment, long-term orientation and cooperation. This study, which used data from participating in the business-to-business e-marketplace companies, showed acceptable data-fit of proposed model and supported all of research hypotheses. The empirical results indicated that trust take significant effect on commitment, long-term orientation and cooperation, and the commitment affect long-term orientation and cooperation, and the commitment in turn have strong influence on long-term orientation and cooperation. It was confirmed that commitment variable is effective mediator linking trust and long-term orientation and cooperation.

• 재무관리연구
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• 제25권4호
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• pp.145-182
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• 2008

As the life expectancy increases resulting in the aged society, the post-retirement life became one of the most important concerns of people. The long-term investment vehicles such as retirement savings and pension plans have been introduced to meet such demand of society. This paper examines the impact of asset allocation strategies on the long-term investment performance. Because of the unusually long investment horizon and the compounding effect, a suboptimal asset mix in a retirement plan can be a very costly and irreversible mistake. Instead of relying on anecdotal evidence to evaluate the merits of different allocation strategies, this paper performs various tests including stochastic dominance tests using both actual data and Monte Carlo simulated data that best fit the historical experience. The results indicate 1) the long-term investments perform better than the short-term investments, 2) the optimal asset allocation strategy for the long-term investments should be highly equity dominated.

• 열처리공학회지
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• 제34권6호
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• pp.294-301
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• 2021

In the present study, we investigate the effects of long-term heat treatment at elevated temperatures on the mechanical softening of the Mn-Mo-Ni low-alloy steel. The influence of long-term heat treatment on microstructure and mechanical strength was evaluated. To simulate the long-term material degradation, heat treatment test was interrupted at several stages up to 10,000 hours in an electric furnace. The Mn-Mo-Ni low-alloy steel shows a typical bainitic phase, which consists of a well-developed lath substructure with fine precipitates along the lath boundaries. However, these fine precipitates were redissolved into the matrix with long-term heat treatment, and then the lath substructures were recovered. Consequently, ultimate tensile strength and yield strength decreased during long-term heat treatment showing a mechanical softening phenomenon.

• KDI Journal of Economic Policy
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• 제31권1호
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• pp.139-167
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• 2009

본 논문은 65세 이상 고령인구의 수와 노인들의 건강상태 등만을 중심으로 한 기존의 연구에 더하여, 노인장기요양보험제도 제2차 시범사업의 자료를 이용한 계량분석을 통해 장기요양서비스 수요의 결정요인을 분석하였다. 분석 결과에 따르면, 우선 노인장기요양보험제도상 장기요양서비스 이용에 대한 보험 적용 대상자를 정하는 등급판정에 일상생활활동에서의 장애가 노인들이 많이 앓고 있는 고혈압, 관절염, 치매 등의 질환을 통제하고서도 통계적으로 유의한 영향을 미쳤다. 또한 노인들의 건강상태, 여성, 기초생활수급자 여부, 노인가구 형태, 노인가구의 월평균 소득 등이 장기요양서비스이용 및 이용 양태에 통계적으로 유의한 영향을 미치는 것으로 나타났다. 특히, 노인가구의 월평균 소득을 통제하고서도 장기요양서비스를 무료로 이용할 수 있는 기초생활수급 대상 노인들의 재가서비스 이용확률이 높게 나타나는데, 이는 소득과 더불어 장기요양서비스의 가격도 장기요양서비스 이용을 결정하는 중요한 요인임을 의미한다.

• 동서간호학연구지
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• 제22권1호
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• pp.24-31
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• 2016

Purpose: The purpose of this study was to identify and compare the differences on perceived health status, Activities of Daily Livings (ADL), social support, and residential satisfaction between long-term care hospitals and nursing homes. Methods: Data was collected through questionnaires and interviews conducted from March 29 to April 22, 2011. The subjects were 66 old adults in 3 long-term care hospitals and 53 old adults in 6 nursing homes. Data were analyzed by Pearson's correlation analysis and t-tests. Results: ADL and subjective health status in nursing homes were worse than those in long-term hospitals, but it was not statistically significant (p>.05). Old adults in nursing homes received more emotional support from other residents and staff, and received more instrumental support from staff than those in long-term care hospitals (p<.001). The mean scores of resident satisfaction in long-term care hospitals and nursing homes were 3.53 ($SD={\pm}0.36$) and 3.97 ($SD={\pm}0.44$), respectively. Resident satisfaction in nursing homes significantly was higher than long-term care hospitals (p<.001). Conclusion: Health care personnels in long-term care hospitals should enhance resident satisfaction and social support and need to coordinate long-stay patients with nursing homes.

• Communications for Statistical Applications and Methods
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• 제24권4호
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• pp.325-337
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• 2017

In this paper, we proposed a new long-term lifetime distribution with four parameters inserted in a risk competitive scenario with decreasing, increasing and unimodal hazard rate functions, namely the Weibull-Poisson long-term distribution. This new distribution arises from a scenario of competitive latent risk, in which the lifetime associated to the particular risk is not observable, and where only the minimum lifetime value among all risks is noticed in a long-term context. However, it can also be used in any other situation as long as it fits the data well. The Weibull-Poisson long-term distribution is presented as a particular case for the new exponential-Poisson long-term distribution and Weibull long-term distribution. The properties of the proposed distribution were discussed, including its probability density, survival and hazard functions and explicit algebraic formulas for its order statistics. Assuming censored data, we considered the maximum likelihood approach for parameter estimation. For different parameter settings, sample sizes, and censoring percentages various simulation studies were performed to study the mean square error of the maximum likelihood estimative, and compare the performance of the model proposed with the particular cases. The selection criteria Akaike information criterion, Bayesian information criterion, and likelihood ratio test were used for the model selection. The relevance of the approach was illustrated on two real datasets of where the new model was compared with its particular cases observing its potential and competitiveness.

• 간호행정학회지
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• 제9권3호
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• pp.353-366
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• 2003

Purpose: This study was to define the care time of elderly in long-term care facilities and to compare and analysis the care time by staff and facility types. Method: The data were collected from 530 elderly over sixty, residing in two long-term care hospitals for dementia, three long-term care hospitals for the elderly and two skilled nursing facilities. Care time for individual residents was measured the total time spent by nurses, aides. Result: The average care time measured by nursing staff was 158.6 minutes a day. The average care time for one resident by nurse was 40.4 minutes, and by aides, 118.2 minutes. The difference of the care time showed statistical significance between long-term care facility types(p<0.001) : average care time for dementia hospital(199.1min) was twice as long as that of skilled nursing facility(94.1min). Conclusion: The results of the study showed that the care time differentiates care time provided to elderly in long-term care facilities in Korea. The study suggests the need to emphasize the importance of standardization of level of staff and service programs by the long-term facilities.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.101-101
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• 2020

Traditional stochastic simulation of hydroclimatological variables often underestimates the variability and correlation structure of larger timescale due to the difficulty in preserving long-term memory. However, the Long Short-Term Memory (LSTM) model illustrates a remarkable long-term memory from the recursive hidden and cell states. The current study, therefore, employed the LSTM model in stochastic generation of hydrologic and climate variables to examine how much the LSTM model can preserve the long-term memory and overcome the drawbacks of conventional time series models such as autoregressive (AR). A trigonometric function and the Rössler system as well as real case studies for hydrological and climatological variables were tested. Results presented that the LSTM model reproduced the variability and correlation structure of the larger timescale as well as the key statistics of the original time domain better than the AR and other traditional models. The hidden and cell states of the LSTM containing the long-memory and oscillation structure following the observations allows better performance compared to the other tested conventional models. This good representation of the long-term variability can be important in water manager since future water resources planning and management is highly related with this long-term variability.

• 지능정보연구
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• 제12권4호
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• pp.39-51
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• 2006

선사에서 화물을 수송하기 위해 필요한 공(빈) 컨테이너 수요를 만족시키기 위해서 컨테이너를 구매하고 임대하는 계획을 작성하는 방법에 대해서 다루었다. 수요의 변동을 고려하여 각 기간별로 구매 또는 임대하여야 할 컨테이너의 개수와 임대기간을 결정하는 방법을 제시하였다. 컨테이너 구매 및 임대 계획작성을 위한 확정적 수리계획 모형을 제안하였으며 이 모형의 해를 구하기 위한 발견적 기법을 제안하였다.