• 한국농공학회논문집
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• 제63권2호
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• pp.85-96
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• 2021

Irrigation return flow is defined as the excess of irrigation water that is not evapotranspirated by direct surface drainage, and which returns to an aquifer. It is important to quantitatively estimate the irrigation return flow of the water cycle in an agricultural watershed. However, the previous studies on irrigation return flow rates are limitations in quantifying the return flow rate by region. Therefore, simulating irrigation return flow by accounting for various water loss rates derived from agricultural practices is necessary while the hydrologic and hydraulic modeling of cultivated canal-irrigated watersheds. In this study, the irrigation return flow rate of agricultural water, especially for the entire agricultural watershed, was estimated using the SWMM (Storm Water Management Model) module from 2010 to 2019 for the Madun reservoir located in Anseong, Gyeonggi-do. The results of SWMM simulation and water balance analysis estimated irrigation return flow rate. The estimated average annual irrigation return flow ratio during the period from 2010 to 2019 was approximately 55.3% of the annual irrigation amounts of which 35.9% was rapid return flow and 19.4% was delayed return flow. Based on these results, the hydrologic and hydraulic modeling approach can provide a valuable approach for estimating the irrigation return flow under different hydrological and water management conditions.

• 디지털융복합연구
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• 제12권6호
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• pp.115-123
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• 2014

본 연구는 중소기업을 대상으로 첫째, 매출액순이익률, 총자산회전율 및 부채비율이 주주의 자본수익성지표인 자기자본순이익률에 어떤 영향을 미치는지, 둘째, 총자산순이익률이 자기자본순이익률에 미치는 영향관계를 부채비율이 조절하는지, 마지막으로 수정된 부채비율과 자기자본순이익률과의 영향관계를 실증적으로 분석하였다. 분석결과, 부채사용은 자기자본순이익률에 전반적으로 긍정적인 측면이 있는 것으로 나타났다. 그러나 수정된 부채비율의 2차함수 곡선모형에서 볼 수 있듯이 부채사용은 레버리지효과를 통해 자기자본순이익률의 증 감폭을 크게 확대하고 있음을 알 수 있다. 결국, 부채사용은 동전의 양면과 같이 긍정적인 측면뿐만이 아니라 부정적인 측면을 가지고 있다 할 것이다. 그래서 부채의 사용은 기존의 핵심 사업으로부터 창출되는 영업현금흐름(혹은 총자산영업이익률)으로 이자(혹은 이자율)를 커버할 수 있는 범위 내로 제한되어야 한다는 시사점을 제공하고 있다.

• 한국산학기술학회논문지
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• 제4권4호
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• pp.422-427
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• 2003

본 논문은 1990년부터 1997년 IMF금융위기가 일어난 시점까지 이루어진 다각화 합병과 비다각화 합병기업들의 M&A사례를 표본으로 하여 합병성과를 분석하였다. 합병성과 측정모형은 시장모형(market model)과 시장조정 수익률 모델(market-adjusted return model)을 그리고 검증은 t-통계량을 이용하였다. 연구결과, 본기간에 발생된 합병성과는 80년대에 비하여 경쟁적이고 보다 자율적인 M&A특성으로 인하여 비다각화합병 기업에게 부(-)의 성과가, 다각화합병기업에게는 정(＋)의 성과로 나타났다.

• 산업경영시스템학회지
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• 제43권4호
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• pp.229-235
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• 2020

Investors aim to maximize the return rate for their own investment, utilizing various information as possible as they can access. However those investors, especially individual investors, have limitations of interpretation of the domain-specific information or even the acquisition of the information itself. Thus, individual investors tend to make decision affectively and frequently, which may cause a loss in returns. This study aims to analyze analysts' target price and to suggest the strategy that could maximize individual's return rate. Most previous literature revealed that the optimistic bias exists in the analysts' target price and it is also confirmed in this study. In this context, this study suggests the upper limit of target rate of returns and the optimal value named 'alpha(α)' which performs the adjustment of proposed target rate to maximize excess earning returns eventually. To achieve this goal, this study developed an optimization problem using linear programming. Specifically, when the analysts' proposed target rate exceeds 30%, it could be adjusted to the extent of 59% of its own target rate. As apply this strategy, the investors could achieve 1.2% of excess earning rate on average. The result of this study has significance in that the individual investors could utilize analysts' target price practically.

• 한국물환경학회지
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• 제25권4호
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• pp.530-538
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• 2009

The Oxic-Settling-Anaerobic (OSA) treatment process, a modified Conventional Activated Sludge (CAS) process, was developed for the purpose of sludge reduction. The insertion of a sludge holding tank into a sludge return line, an anaerobic reactor, forming an OSA process, may provide a cost-effective way of reducing excess sludge production during a process. The OSA process was evaluated for its sludge reduction ability by kinetic parameter and mass balance, with an observed excess sludge reduction of 63.5%, as $P_{X.VSS}$, compared with the conventional activated sludge process.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.245-251
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• 2006

The main idea of this study is to turn attention on the question of good cooling ability of customer substations in large district heating networks. The main reason for that is based on our experience that the optimization of district heating very often is directed toward production, whereas questions of optimal distribution are neglected if only the necessary load can be supplied and the customer's request for comfort is met. Our view is that low return temperature(operational temperature differences, ${\Delta}T$) in district heating systems is an Important feature for efficient net operation and gives both economic and operational benefits to the district heating supplier Furthermore, it is as well a prerequisite for meeting the customers demand for reliable supply of the heat load. However, in many practical cases we have seen that district heating return temperatures are higher than necessary. Hence, the aim of the study is to propose and verify a method for detection of the most critical consumers of the net and to identify the reasons for resulting high return temperature. From the results, temperature control system is presented as one of the most important reason of high return temperature in DH networks.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2007년도 추계학술대회
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• pp.503-516
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• 2007

USA has distinct differences of economic policy by a ruling party. And, USA economy has mainly influenced on it of Korea. So, we examine whether a ruling party of Korea has different regime including rate of return in stock market. The Republican Party and Democratic Party have based on Milton Friedman and Keynes economy at each other's economic policy in the USA The Republican Party and Democratic Party have different interest level and excess return on equity, GDP growth rate, unemployment rate. Also, a ruling party of Korea has different regime and economic activity in this paper.

• 디지털산업정보학회논문지
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• 제10권3호
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• pp.119-125
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• 2014

Echo cancellation is required for a dual-duplex high speed communication such as digital subscriber line(DSL), in order to allow each individual loop to operate in a full duplex fashion. Echo cancellation was one of the most difficult aspects of DSL design, requiring high linearity and total echo return loss in excess of 70 dB. For a long and rapidly changing echo response, if the echo is cancelled by an adaptive echo canceller, the echo canceller needs more taps and its performance is decreased. But if the response is divided into several responses, which response is estimated by a adaptive digital filter and combined, the computation complexities are decreased and the performance is increased. Therefore, the adaptive multi-stage echo canceller is proposed to decrease the computation complexity and increase the performance of echo return loss, in which the echo canceller is composed of several stage echo canceller estimating each divided echo response. Through computer simulations, this multi-stage echo canceller is verified to have merits for high speed communications such as DSL application.

• 아태비즈니스연구
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• 제11권3호
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• pp.95-106
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• 2020

Purpose - This study examines the information effect of the disclosure of new office investments on the Korean stock market and investigates determinant of performance of sample firms. Design/methodology/approach - The sample consists of companies listed on the Korean Exchange that announced investments in new office construction for eleven-years from January 2007 to December 2017. It analyzes excess return using event study methodology and studies the determinants of abnormal return with multiple regression analysis. Findings - We find that abnormal returns of the short and long window are positive on average and statistically significant. In particular, CAR of high growth subsample is a larger positive return than that of the low one both short and long window. Difference in abnormal returns by investment size is observed only in short time window. But there is not observed difference by cash holding level. Research implications or Originality - This finding is able to be added to the evidence of the theory of corporate value maximization academically. Moreover, it shows the possibility that building a new office can have a positive effect on corporate value. It is expected to help investors make decisions because it can provide useful information to market participants in practice.

• 한국건설관리학회논문집
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• 제10권2호
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• pp.121-131
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• 2009

본 연구에서는 우리나라에서 시행되었던 BTO 민간투자사업의 자료를 이용해 BTO 민간투자사업에 투자되는 민간자본에 대한 적정수익률을 추정하고자 한다. 과거 우리나라에서 진행되었던 민간투자사업의 경우 민간자본에 제공된 실질수익률은 대략 $6%\sim9%$ 수준이었는데, 본 연구의 결과에 따르면 정부가 최소운영수입을 보장해준 과거 민간투자사업의 경우, 민간자본에게 제공되었던 수익률은 적정 수준을 상당히 초과하는 것으로 나타났다. 특히 대부분의 민간투자사업에 있어 실제 운영 수입이 실시협약 당시 예측된 운영수입에 현저히 못 미친다는 점을 고려할 때, 민간자본에 대한 적정수익률은 더 낮아지게 되며 따라서 과거에 제공된 수익률의 적정수익률 대비 초과분은 더욱 커지게 된다. 본 연구결과는 향후 BTO방식 민간투자 사업을 진행할 때 정부와 민간사업자간의 실시협약조건에 민간 사업자가 부담하는 위험 대비 적정수익률이 반영될 수 있도록 하는데 도움을 줄 것으로 예상된다.