• Journal of the Korean Society of Child Welfare
• /
• no.55
• /
• pp.1-29
• /
• 2016

The purpose of this study was to investigate the influence of household income on children's academic achievement, and to identify the mediating effects of parental time and material investment in the relationship between the two variables. We utilized the third-wave data of the "Seoul Panel Study of Children Surveys(SPSC, 2006)". The major findings of the present study are as follows. First, the results show that household income has a positive influence on children's academic achievement. Second, parental material investment fully mediates the influence of household income on children's academic achievement. Among the variables representing parental material investment, the mediating effects of "purchasing of cognitively stimulating materials" and "participating in extracurricular activities' are found to be statistically significant. However, the two variables representing parental time investment ("parent activities with child out of home" and "parent involvement in school") do not have any significant influence on children's academic achievement. These results indicate that the influence of household income on children's academic achievement can be better explained by parental material investment rather than parental time investment. Implications for policy and practice are discussed.

• Environmental and Resource Economics Review
• /
• v.5 no.2
• /
• pp.253-278
• /
• 1996

본 연구는 전력사업에서 공급설비가 다양할 때 계절 시간대별 요금에서 최적투자 및 가격정책을 도출하기 위한 동태적 분석방법을 제공하는 데 있다. 이를 위하여 수요의 교차 가격탄력성을 고려한 동태적 모형을 설정하여 최대원리법(Maximum Principle)을 적용하였으며, 최적해 도출시 해석적 방법을 이용하여 모형의 수리적 해석에 대한 방법론을 제시하였다. 특히 순 사회편익을 목적함수로하고 이를 최대화하는 제어변수를 설비투자로하여 각 시간경로 (Time Path)에 따른 최적 가격이 단기 및 장기 한계비용과 어떻게 연관되는지를 보여주었다. 또한 제어변수인 설비투자가 계속적인 수요증가가 발생하는 시간경로에 따라 최적값이 어떻게 변하는지도 보여 주었다.

• The Journal of the Korea Contents Association
• /
• v.22 no.2
• /
• pp.593-604
• /
• 2022

This study examines how auditors respond to labor investment inefficiency, specifically its impact on audit fees and audit hours. Using a sample of Korean firms listed on the Korea Stock Exchange from 2003 to 2018, our empirical results indicate that firms involved in inefficient investment in labor incur higher audit fees and audit hours. This implies that auditors consider inefficient labor investment to cause considerable business risk, thus requesting higher external audit fees to compensate for higher audit risk. Furthermore, auditors expend more time and effort while auditing those firms by expanding the audit procedures to reduce the audit risk to an acceptable level. Finally, this study provides empirical evidence on whether the investment inefficiency in labor, an important factor in firms' competitiveness, incur higher audit fees as well as audit hours.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.7 no.3
• /
• pp.661-670
• /
• 2012

In order to construct a profitable stock trading model, three considerations must be resolved in the model in integrated manner: profit principle, trader's conditions and stock market trends. Generally, a model will be developed through long experiences of stock trading that requires quite amount of expenses and time. This paper analyzes the issues involved in those considerations and proposes a road map for a trading model.

• Journal of Korean Society of Transportation
• /
• v.17 no.2
• /
• pp.193-198
• /
• 1999

An asymptotic distribution of the ratio of two normal vectors is estimated. Using the estimated asymptotic distribution, an approximation method to estimate confidence interval of passenger's value of travel time is proposed. As a result of empirical study the 95% confidence interval of value of travel time of home-to-work trips in city of Seoul is estimated at ￦7341.25$\pm$1945.05/hr.

• Korean Management Science Review
• /
• v.4
• /
• pp.42-53
• /
• 1987

FMS는 개별적인 자동화 체계와 기술이 하나의 생산시스템 내에서 통합된 것이므로, 이는 다품종 소량생산 방식에 있어 높은 생산성과 융통성을 동시에 달성하고자 하는 제조시스템이다. FMS와 같은 신제조 기술에 바탕을 둔 공장자동화 시스템을 설치, 운영함에 있어 고유한 생산관리상의 제문제가 발생하며, 특히 막대한 투자비 소요로 인한 경제적 타당성 평가 문제가 FMS 도입상 선결과제로 대두되고 있다. 본 연구는 지금까지 발표된 FMS투자 타당성 검토와 관련된 종합적인 문헌 조사를 행한 후, 이를 크게 "계량요인 위주기법"과 "비계량요인 포함 기법"으로 구분하고, 각 구분에 속한 제 평가 방법들의 특성 및 한계점을 파악하고자 한다. 아울러 FMS 투자타당성 검토 대안으로서 시간적 차원을 달리하는 3단계적 평가 방법을 제시하고자 한다.단계적 평가 방법을 제시하고자 한다.

• Journal of Korean Society of Transportation
• /
• v.28 no.2
• /
• pp.65-75
• /
• 2010

When the cost-benefit analysis is applied for social discount rate(SDR), the choice of SDR to be used in analysis is critical. One of the important issues when public investment project evaluate what is the SDR theory, so there have studied about SDR and no exact answer it so far. In this study, there are three of SDR theories that be estimated social time preference rate, social investment returns and the weighted average method from 1990s, 2000 to 2003 and 2004 to 2008.. First, social time preference method computes consumer's interest rate and the model of Pearce and Ulph(1999). Second, social investment returns method computes private returns of capital. Third, the weighted average method computes the model of Squire, L., Herman G. van der Tak(1975) and private consumption expense and the private investment expense. SDR is estimated in the rage between 2.4% and 3.9% from 2004 to 2008. It is not appropriate that the interest rate was unstable. But it is consider for social equity from present to future generations. Considering this things, downward need to the value of current SDR 5.5%.

• Journal of Korea Port Economic Association
• /
• v.37 no.2
• /
• pp.119-131
• /
• 2021

Energy is an essential element in economic activity and people's lives, an important resource used by various industries, and the financialization of commodity markets has led to the growing importance of crude oil turning into the same asset as other assets. Accordingly, studies analyzing the correlation between energy prices and investor sentiment explain that investor sentiment affects oil prices through economic factors and speculation. In this study, we wanted to analyze whether the impact of the most representative changes in oil prices affects investor decision making, affecting investor sentiment, and applying wavelet consistency analysis to determine how energy prices relate to investor sentiment. Studies show that policies should be focused on policy and market changes because energy prices differ by time scale and investment sentiment should be more influential in the long term than in the short term.

• Journal of the Korean Society of Child Welfare
• /
• no.60
• /
• pp.25-57
• /
• 2017

The effects of regular and active leisure activities on positive growth and development in adolescents are widely known. In our society, however, it is challenging to enjoy or expand such activities due to diverse constraints. Under unfavorable circumstances, this study attempted to investigate the application of time availability for liberal leisure activities as a way to help adolescents engage in active leisure activities. Specifically, this study examined the relationship between time availability (both individual and structural) and the time invested in leisure activities at youth training centers which support such leisure activities. The study found the following results: As both individual and structural time availability expanded, the time invested in leisure activities increased as well. Based on these results, this study discussed policy and practice implications regarding the support of adolescents' leisure activities.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.7
• /
• pp.63-76
• /
• 2016

Most previous studies found a positive relationship between the value of a firm and its R&D investments. This research measures the impact of the timescale of the R&D investment of a firm on its value using panel vector autoregression. By measuring the time required for R&D to impact the value of a firm, this study demonstrates that the lead time is an essential factor in the analysis of the effect of R&D investment on a firm's value. Our study finds that the length of the lead time varies according to the firm's size, industry concentration, and book to market ratio. Firms with a higher industry concentration show a shorter lead time. Also, firms with a larger size and higher book to market ratio generally show a shorter lead time.