• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.561-566
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• 2002

As the air pollution caused by diesel vehicles goes worse, so non-road vehicles exhaust gas standards are more strict in an foreign countries. There is growing evidence that diesel vehicles could play the important role in determining health effects. Most of the particle number emitted by diesel engines is in the nanopaticle range, D$\_$p/ < 50nm, while most of the mass is in the accumulation mode, 50nm < D$\_$p/ < 1000nm range. The aim of this work was to investigate pollutants in the exhaust of railroad diesel rolling stock under load tests.

• 재무관리연구
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• 제20권1호
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• pp.191-212
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• 2003

주가지수선물의 도입은 현물주식시장의 정보 비효율성을 완화시켜 현물주식시장에서 변동성의 비대칭성이 줄어든다는 주가지수선물의 도입 효과를 살펴보기 위하여 KOSPI 200 주가지수 선물 도입 전 후를 대비하여 현물주식시장의 변동성에 대한 비대칭성 정도를 비교분석 하였다. 변동성의 비대칭성을 반영하는 TGARCH 모형을 이용하여 비대칭 비율(asymmetry ratio)을 추정하고 모형의 적합성 검진(diagnostic test)을 통해 비대칭성을 반영하지 않는 GARCH 모형과 비교분석 하였다. 분석결과에 의하면 주가지수선물 도입 이후 현물주식시장의 변동성은 비대칭적 현상이 줄어들었고 그 결과 주가지수선물 도입 이후에는 비대칭성을 고려한 모형과 그렇지 않은 모형간에 적합성의 차이가 미미하게 나타났다. 그러나 현물주식시장의 비대칭적 변동성의 정도는 시장 상승국면에서 보다는 시장 하락국면에서 더 심하게 나타나는데 주가지수선물이 도입되어도 시장하락국면에서 비대칭성이 더 강하게 나타났다. 하만 도입 이전보다는 어느 정도 완화된 것으로 나타나 현물주식시장에서 주가지수선물 도입의 완화 효과를 부정할 수 없을 것으로 판단된다. 한편 동일한 분석기간 동안 주가지수선물시장에서도 변동성의 비대칭성이 발견되었다. 그러나 비대칭적 변동성의 정도가 현물주식시장에 비해서는 상대적으로 적게 나타나 현물주식시장보다는 정보가 가격에 신속하게 반영되고 현물주식시장 보다 공매가 용이하여 양방향의 정보에 모두 자본화할 수 있기 때문으로 사료된다.

• 한국산림과학회지
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• 제98권2호
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• pp.133-141
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• 2009

This study was conducted to support for determining an efficient sampling design for forest resources assessments in South Korea with respect to statistical efficiency. For this objective, different systematic sampling designs were simulated and compared based on an artificial forest population that had been built from field sample data and satellite data in Yang-Pyeong County, Korea. Using the k-NN technique, two thematic maps (growing stock and forest cover type per pixel unit) across the test area were generated; field data (n=191) and Landsat ETM+ were used as source data. Four sampling designs (systematic sampling, systematic sampling for post-stratification, systematic cluster sampling, and stratified systematic sampling) were employed as optimum sampling design candidates. In order to compute error variance, the Monte Carlo simulation was used (k=1,000). Then, sampling error and relative efficiency were compared. When the objective of an inventory was to obtain estimations for the entire population, systematic cluster sampling was superior to the other sampling designs. If its objective is to obtain estimations for each sub-population, post-stratification gave a better estimation. In order to successfully perform this procedure, it requires clear definitions of strata of interest per field observation unit for efficient stratification.

• 한국동물위생학회지
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• 제44권4호
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• pp.217-225
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• 2021

We investigated the effect of temperature and stock density on the collection efficiency of oral fluid in the pig farm in Korea. Three pig farms with similar breeding environmental conditions were selected and four pens of each farm (total 12 pens) were tested for the collection efficiency of oral fluid from pigs. Collection rate was considered as significant when oral fluid was collected from 70% of pigs within a pen. In the case of growing pigs, when internal temperature of pig barn increased by one designated degree (5℃), the oral fluid collection rate significantly decreased by 24.7% (P<0.05). The collection rate of oral fluid also decreased by 7.1% (P<0.05) as the density rate increase by one designated degree (12.5%). It was estimated that the collection efficiency of oral fluid decreased when the internal temperature of pig barn was 30℃ or higher, or barn density is higher 25% or high. On the other hand, in the case of stall-housing sows, unlike growing pigs, there was no significant differences according to the temperature, so oral fluid collection was considered to be efficient even in hot season.

• 한국주거학회논문집
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• 제14권3호
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• pp.147-156
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• 2003

A small apartment housings in Korea, which is built mass-product from 1980s, are dissatisfied, in spite of good condition, due to the growing living areas and changing lifestyle of the residents. Many of them confronted with slum areas and the kinds of housing stock accumulated much more in Korean contexts. For the existing small houses, it could be discuss an adaptation model to the increasing requirement standards of the house residents; wider living area, new facilities and a style of new residence. A social policy for elderly people who are handicap in physical and economical aspects, is home stay system rather than national support. But it is not easy to find the three generation family house in Korea context, specially apartment house. This paper deals with the vertical unification typology of two dwelling units to one, in order to supply three generation houses by remodel existing small apartment houses constructed by Korea National Housing Corporation. The use of convert houses into vertical expansion are expected to be a house of three generation family, it can also enhance privacy against conflictive activities in a house. And also the merging types of two dwelling units into one can be used as a device to get rid of the monotonous characteristics and gain diversity in the declining stock housing.

• The Journal of Asian Finance, Economics and Business
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• 제7권4호
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• pp.51-58
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• 2020

The study aims to investigate the relationship between hedging with derivatives and subsequent firm-level stock price crash risk. Our sample consists of KOSPI- and KOSDAQ-listed companies from 2004 to 2014. The total firm-year observation is 4,886. We find that hedging with derivatives is related to greater possibilities of crash risk. The results suggest that the complexity of economic and financial reporting for derivatives may aggravate the company's information opacity, ultimately increasing the crash risk. We contribute to the growing body of literature on hedging with derivatives. Academics and practitioners have debated on whether or not hedging enhances transparency or rather makes the information environment more opaque. Theoretical research on the role of corporate hedging on information environment shows that hedging enhances earnings informativeness. Meanwhile, pieces of anecdotal and empirical evidence show that the economic and financial reporting complexity of derivatives can harm information transparency. Our results shed light on the question of whether and how hedging with derivatives affects information environment by examining the relationship between hedging with derivatives and crash risk. Furthermore, our findings provide useful insights for policymakers and practitioners. Specifically, our results raise a need for a more transparent disclosure on corporate hedging activities with derivatives.

• 유통과학연구
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• 제11권11호
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• pp.5-11
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• 2013

Purpose - Considering corporate companies that are continually growing and bearing in mind the theory of agency, how confident can stakeholders be about their benefits in relation to managers' decisions? Previous research has indicated that the type of corporate governance can have an effective impact on companies' performance. The current study aims to investigate the impact of ownership structure on listed companies on the Tehran Stock Exchange. Research Design, Data, and Methodology - Through use of the correlation coefficient, the results indicate a positive correlation among the percentage of common stock held by board members, the percentage of non-executive board members, and separation of the positions of chairperson of the board of directors and managing director. Results - Based on the return on assets index, only the correlation between the proportion of ownership of the managing director and financial investment company ownership is significant. Conclusion -Managers can potentially make decisions that benefit themselves but are detrimental to shareholders' interests. Corporate governance is a factor that can mitigate agency costs. Corporate governance comprises the laws, regulations, structures, processes, cultures, and systems that lead to the achievement of objectives such as accountability, transparency, justice, and stakeholders' rights.

• 한국산업정보학회논문지
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• 제24권1호
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• pp.23-30
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• 2019

딥러닝 네트워크 기반의 알고리즘의 발전으로 인공지능은 전세계적으로 빠른 성장세를 보이고 있다. 그 중 금융은 인공지능이 가장 많이 활용될 분야로 예상되고 있으며 최근 많은 연구가 되고 있다. 기존의 딥러닝을 사용한 재무 전략은 단일 종목에 대한 주가 예측에만 치중되어 있어 변동성에 취약하다. 따라서 본 연구는 딥러닝을 이용하여 펀드 구성 종목을 산출하고 종목들을 분산투자하여 ETF 상품을 구성하는 모델을 제안한다. 실험 결과로 제안하는 모델을 통해 코스피 100 지수를 대상으로 하는 성능을 분석하며 수익률 또는 안정성 측면에서 향상된 결과를 확인하였다.

• The Journal of Asian Finance, Economics and Business
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• 제9권9호
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• pp.93-104
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• 2022

This study aims to investigate the factors that contribute to the sustainable development of 334 Vietnamese construction and real estate companies listed on the Stock Exchange of Vietnam over a 5-year period from 2016 to 2020. By using regression analysis with the support of STATA software through examining the financial statements, which involves looking into crucial ratios including capital structure, profitability, firm size, accounts receivable management, and tangible assets investment, this study sheds light on whether these accounting indicators could help predict the construction and real estate companies growing potential in the future. Nevertheless, these ratios slightly contribute to the explanation of the change in revenue growth ratio, with a result of 1.6%, indicating that the value relevance of accounting information provides a modest and insignificant effect on investment decisions. This is understandable because the Vietnamese construction and real estate market still has many shortcomings in handling unexpected events, as well as the industry's peculiarities related to major capital sources from bank loans. Based on this study, governmental authorities and business executives should plan appropriate risk management policies and measures to contribute to the sustainable development of construction and real estate companies.

• The Journal of Asian Finance, Economics and Business
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• 제9권2호
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• pp.177-183
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• 2022

The COVID-19 pandemic has hurt the economy and negatively impacted all enterprises' financial performance. The COVID-19 pandemic has put a strain on global manufacturing capacity and supply chains, and it is also the pandemic that has given up new opportunities for the logistics industry to develop as e-commerce has developed. By analyzing the financial performance of logistic firms listed on the Vietnam Stock Exchange, this study tries to quantify those consequences. A total of 114 logistic companies were included in the study's sample. The Wilcoxon Signed Rank Test was performed to test the difference between some ratios in 2019 and 2020. This study found that the financial performance of 114 logistic firms listed on the Vietnam stock exchange has not improved. The data show that during the COVID-19 pandemic, the leverage ratio increased while the profitability and efficiency ratios decreased. The liquidity ratio did not show any significant differences. On the contrary, these businesses' performance, such as returns on assets, receivable turnover, and leverage, has decreased. The COVID-19 had a global impact on supply chains, therefore export activity and international transportation were badly hampered, with only a few domestic logistic enterprises growing.