• The Korean Journal of Financial Management
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• v.21 no.1
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• pp.231-253
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• 2004

We examine hedge strategies that use Won-dollar futures to hedge the price risk of the Won-dollar exchange rate. We employ the naive hedge model, minimum variance hedge model and bivariate ECT-ARCH(1) model as hedge instruments, and analyze their hedge performances. The sample period covers from January 2, 2001 to December 31, 2002 with sub-samples such as daily, weekly, bi-weekly prices of the Won-dollar futures and cash. The important findings may be summarized as follows. First, there is no significant difference in hedge ratio between the risk minimum variance model and bivariate ECT-ARCH(1) model that controls for the cointegration relationship of the Won-dollar futures and cash. Second, hedge performance of the naive model and minimum variance model with constant hedge ratios is not far behind that of bivariate ECT-ARCH(1) model with time-varying hedge ratios. This results imply that investors are encouraged to use the minimum variance hedge model to hedge Won-dollar exchange rate with Won-dollar futures. Third, hedge performance and effectiveness of each model is also analyzed with respect to hedge period appear to be greater over long than over the short period. This evidence supports the hypothesis that futures prices would have more time to respond to the greater cash price changes over the longer holding period, leading to an improved hedge performance.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.7 no.4
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• pp.49-54
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• 2012

In this paper, a software policy considering testing time and the number of errors corrected is presented. The software is tested until a specified testing time or the time to a specified number of errors are corrected, whichever comes first. The model includes the cost of error correction and software testing during the testing time, and the cost of error correction during operation. It is assumed that the length of software life cycle has no bounds, and the error correction follows an non-homogeneous Poisson process. An expression for the total cost under the policy is derived. It is shown that the model includes the previous models as special cases.

• Journal of Labour Economics
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• v.25 no.1
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• pp.47-74
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• 2002

Since the Economic Crisis at the end of 1997, unemployment rate soared up to the record-high 8.6% (February 1999) and, for youth aged 15~29, it was 14.6% (27.8% for aged 15~19). In spite of economic recovery after the crisis, new participants in labor market at the school-to-work transition have faced with difficulties in finding their first jobs and, even further, the ratio of youth at out-of the labor force but not in school has remained at a higher level. It is important to calibrate the negative effects of nonemployment in the short-run as well as in the long-run, but there has been few study on the school-to-work transition in Korea. This study focus on the nonemployment duration to first job after formal education and comparison of its pattern before and after the crisis. A proportional hazard model, considering job prenaration before graduation (21.4% of the sample), with the semi-parametric baseline hazard is applied to the sample from the Korean Labor and Income Panel Survey(1998~2000) and its Youth Supplemental survey(2000). Interview of the Survey is conducted, by the Korea Labor Institute, to the same 5,000 household and 13,738 individual sample, guaranteeing nationwide representativeness. The Supplemental Survey consists of 3,302 young individuals aged 15 to 29 at the time of survey and 1,615 of them who are not in school and provide appropriate information is used for the analysis. The empirical results show that there exists negative duration dependence at the first three or for months at the transition period and no duration dependence since a turning point of the baseline hazard rate and that unemployment rate reflecting labor demand conditions has a positive effect on exiting the nonemployment state, which is inconsistent with a theoretical conclusion. Estimation with samples separated by the date of graduation before and after the crisis shows that the effect of unemployment rate on the hazard was negative for the pre-crisis sample but positive for the post-crisis sample.

• 한국IT서비스학회:학술대회논문집
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• 2006.11a
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• pp.512-512
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• 2006

1999년부터 2004년까지 세계 주요국가의 정보통신산업의 투자현황과 경제지표를 기반으로, 정보통신산업의 투자가 어떻게 국가경제 발전에 영향을 미치는지를 연구한다. 이 주제의 다른 연구들에 비하여 방법론적인 차이점은, 첫째 인터넷 거품 현상의 와중과 그 이후의 기간을 모두 고려했다는 점, 둘째, 정보통신 투자의 영향이 발현되는데 다소 시간의 경과가 필요하므로 Malmquist 방법을 이용한 통시적인 접근을 사용했다는 점, 셋째, 각 국가의 고유 현상이 고려된 모형하에서 분석되어야 한다는 점 등이다. 분석방법을 이끄는 주요 이론적 기반으로는, 정보기술의 경제적 가치를 인프라와 응용기술로 구분하여 분석하는 Barua, Kriebel & Mukhopadhyay (1995) 의 Two way approach를 채택하고자 한다.

• Korean Journal of Construction Engineering and Management
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• v.23 no.3
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• pp.83-94
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• 2022

The number of public rental housing has increased according to the government's 「Housing Welfare Roadmap (2017)」, and facility maintenance costs for the demand of improvement of performance and residential standards due to the aging of long-term public housing are significantly increasing. Consequently, the financial burden of public housing rental business for maintaining stocked housing is aggravated. However, there is a lack of objective data to analyze the size of the maintenance costs that are executed by the type of repair work, and the elapsed years of the aged long-term public rental housing. This study analyzes the execution status of 33 long-term public rental housing complexes located in Seoul for 14 to 28 years of elapsed years based on the data of maintenance costs. In addition, this study proposes a model to predict the maintenance costs by elapsed years by dividing 'Long-term Repair Plan Work and Government-Funded Project [Y₁]', 'Planned Repair Work and General & Unplanned Repair Work [Y₂]', and 'Total maintenance costs [Y₃]'. It is intended to be used as basic data for the establishment of the maintenance plan at the stage of setting up the budget and the establishment of the sustainable operation plan for public rental housing

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.105-105
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• 2017

최근 우리나라에서는 국지성호우로 인해 발생하는 돌발홍수에 방어하지 못하는 소규모 저수지에 대한 붕괴사고가 빈발하고 있다. 붕괴된 저수지를 살펴보면, 대체적으로 규모가 작아 체계적인 안전관리가 이루어지지 않거나 경과연수가 50년 이상인 필댐(fill dam) 형식으로 축조된 노후저수지로서 갑작스러운 홍수를 대응하는데 있어 매우 취약한 상태이다. 체계적으로 운영되는 대형댐에 비해 축조기간이 오래된 소규모 저수지의 경우, 저수지에 대한 수문학적 정보가 거의 없거나 미계측되어 보수보강이 필요한 저수지를 선정하거나 정량적인 위험도를 분석하는데 매우 어려운 실정이다. 이러한 이유로 본 연구에서는 노후된 소규모 저수지에 대한 수문학적 파괴인자들을 선정하여 Bayesian Network기반의 소규모 저수지 위험도 분석 모형을 구축하였다. 구축된 모형을 기준으로 고려될 수 있는 다양한 위험인자 및 이들 인자간의 연관성을 평가하였으며, 각각의 노드에 파괴인자를 노드로 할당하여 소규모 저수지의 위험도를 분석하였다. Bayesian Network기법의 도입으로 불확실한 상황을 확률로 표시하고, 복잡한 추론을 정량화된 노드의 관계로 단순화시켜 노드의 연결 관계로 표현하였다. 본 연구에서 제안된 모형은 노후된 소규모 저수지의 수문학적 위험도를 정량으로 분석하는 모형으로서 활용성이 높을 것으로 기대된다.

• Journal of Labour Economics
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• v.26 no.2
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• pp.1-30
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• 2003

The recent experience about self-employment shows three main trends: first, its share out of the total workers has steadily increased, recording 37.6% in 2001, implying its prevalence and importance; second, its share out of male workers has caught up female workers', implying its importance to males as well as females; and finally, during the recent Economic Crisis when there was mass layoff and large scale bankruptcy, its share rapidly increased, reflecting its role of a buffer to economic fluctuation. However, there have been few studies on self-employment, mainly focusing on what makes someone choose it as an alternative to being employed. This study analyzes the determinants of the duration to terminate self-employment, by applying the proportional hazard model to the Korea Labor and Income Panel Survey(KLIPS) by the Korea Labor Institute. The KLIPS started the first wave in 1998 with the 5,000 household sample (and about 12,000 individual sample of household members aged 15 and more). In this study, the first four waves are used for analysis. The average duration of 5,357 spells of self-employment is 130 months. It shows slight difference between males(124 months) and females(138 months) while it widely ranges over industries (296 months for agriculture industry while 50 months for restaurant and hotel industry). Estimates of the proportional hazard model of the self-employment duration show that females are more likely to terminate self-employment while it is not statistically significant. The effect of age at starting self-employment on the hazard shows the inverse V-shape, which implies that, until a certain age(47 years), the hazard become higher as aging while, since then, it become lower as aging. The level of education has a positive effect on the hazard, implying that more education is related to the higher probability to be employed. The measures of economic performances, annual sales and earnings, are positively related to continuing self-employment while hardship at the start of self-employment measured by several ways has a negative effect. Training before opening business has a positive effect on keeping on self-employment and its effects are different over its providers, significantly positive for public providers while insignificant for private providers. More and further research on self-employment is urgent in the rapidly ageing society. To help workers to be self-employed, more public assistance is necessary for education, training, financing, marketing, management, and human resource management in order to make the olders consider self-employment as a good alternative rather than an inevitable one.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1464-1468
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• 2004

누후된 상수도 관망의 최적개량 계획수립을 위하여 많은 모형들이 개발되었으며, 이러한 모형들은 수리학적 타당성을 비롯한 다양한 인자들을 복합적으로 고려한다. 관망의 수리학적 타당성을 검토하기 위해서는 관망해석을 통해 절점 압력변화 등이 계획기간동안 만족되어야 하며, 이를 위해서는 관거의 노후정도에 따라 변하는 Hazen-Williams C상수의 변화를 고려하여야 한다. 그러나 Hazen-Williams C상수의 변화는 관거의 매설지역, 통수년수, 수질 등과 같은 여러 가지 복합적인 인자에 의해 차이가 있으며 실제 유량 및 압력자료 등에 대한 조사에 의해 매설된 관거의 C상수를 추정하여야 한다. 그러나, 내상 지역의 모든 관거에 대하여 유량과 압력을 조사하는 것은 경제적인 문제를 비롯한 여러 가지 이유로 불가능하므로 본 연구에서는 실측된 몇몇 지점의 유량 및 압력 변화에 따라 대상지역에 매설된 관거의 C상수 변화를 추정하는 알고리즘을 제시하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.221-232
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• 1993

In this study, the period for stabilization in the case of recycling leachate was compared and analyzed with the case of non-cycle type, using lysimeters filled with municipal organic refuse. The lysimeters were operated with various detention time. In addition, the degree of stabilization was estimated by the way of measuring the quantity of gas from landfills. As the results, the recycle of leachate, which was modified as the neutral level of pH, accelerated the biological decomposition of organics with the raped growth of anaerobic bacteria in the system, and reduced the period for the stabilization. In the case of BOD and COD in leachate, COD. which had been originality similar to BOD, had increased more rapidly than BOD as time lapsed. Moreover, the quantity of gas from the recycle reactor was larger than from the non-cycle reactor. The shorter the detention time of leachate gas, the larger the quantity of gas produced in the lysimeters.

• Korean Journal of Social Welfare Studies
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• v.44 no.3
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• pp.301-322
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• 2013

By analyzing wave 1~11 (1998~2008) of Korean Labor and Income Panel Study(KLIPS) database, this study examines the effects of household characteristics and poverty duration on poverty exit. A special concern is to decide whether the decrease of poverty exit rates comes from true duration dependency or from the sample heterogeneity as poverty duration progresses. I also analyzed how the effects of independent variables are changed when unobserved heterogeneity is controlled. The results show that duration dependency disappears after controlling observed household characteristics and unobserved individual heterogeneity. This finding confirms that the apparent relationship between poverty exit rate and poverty duration is in fact a spurious association due to the sample heterogeneity rather than true duration dependency. In addition, the effects of household characteristics on poverty exit rate become more stronger when unobserved heterogeneity is controlled. Socioeconomic factors affecting poverty exit rates are such as householders' age, education, household composition, number of family members, labor force participation, and work status.