• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.546-550
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• 2007

수중보는 하천, 하수관 또는 인공수로에 건기시 유지수량을 확보할 목적으로 설치되며 보통 10년 주기 내외의 평균 강우량에 맞추어 그 용량을 결정한다. 수처리를 위한 장치의 규모는 적정한 재현기간에 맞추어 설계하고, 재현기간을 초과하여 강우가 발생할 경우 강우 유입을 우회시켜 경제성을 확보할 수 있어야 한다. 따라서 완충회전수문은 초과하는 수량을 우회 또는 통과시킬 목적으로 개발되었으며 기존 연구에서 실내 및 현장 실험 모형을 제작하여 여러 차례 실험을 토대로 한계수심 및 충격량을 이론적으로 산정하고 현장 적용성을 검증한 바 있다. 본 연구에서는 수문의 개 폐시 원형실린더에 부착되어 있는 날개의 길이 및 개수 변이에 따른 항력의 영향으로 충격량을 측정하여 현장에 보다 적합한 완충회전수문의 최적설계방안을 제시하고자 한다.

• Journal of the Korean Institute of Gas
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• v.26 no.4
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• pp.9-17
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• 2022

This paper is the continuation of our previous paper, which we refer to as numerical analysis of phase behavior and flow properties in an injection tubing during gas phase CO₂ injection. Our study in this paper show the results during supercritcal CO₂ injection under the same project. Geological CO₂ storage technology is one of the most effective method to decrease climate change due to high injectivity and storage capacity and economics. A demonstration-scale CO₂ storage project was performed in a deep aquifer in the Pohang basin, Korea for a technological development in a large-scale CO₂ storage project. A problem to consider in the early stage design of the project was to analyze CO₂ phase change and flow characteristics during CO₂ injection. To solve this problem, injection conditions were decided by calculating injection rate, pressure, temperature, and thermodynamic properties. For this research, we simulated and numerically analyzed CO₂ phase change from liquid to supercritical phase and flow characteristics in injection tubing using OLGA program. Our results provide discharge pressure and temperature conditions of CO₂ injection combined with a pressure of an aquifer.

• Environmental and Resource Economics Review
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• v.16 no.3
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• pp.485-510
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• 2007

The purpose of this paper is to empirically analyze the economic effect of energy saving investment on the improvement of energy intensity. The data used in this paper are panel data, both time-series and cross-section data. In addition, eight manufacturing sectors has been divided into two groups: massive energy consuming (four industries) and non-massive energy consuming (four industries) ones and the time period of analysis is from 1982 to 2004. According to the empirical results, firstly, energy saving investment has a negative relationship with energy intensity, however, its effect is not high in terms of absolute volume of energy consuming. Secondly, in improving energy intensity of energy saving investment, its elasticity IS higher in non-massive energy consuming sector compared it with massive energy consuming sector. Thirdly, automation investment is also playing an important role in energy conservation. The elasticities of automation investment to energy intensity are larger than those of energy saving investment. In terms of the reduction of greenhouse gas per investment unit cost, however, energy saving investment has larger effect than automation investment.

• Journal of the Korean Institute of Gas
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• v.25 no.4
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• pp.10-18
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• 2021

CO₂ storage technology in an aquifer is one of the most effective way to decrease global warming due to a high storage capacity and economics. A demonstration-scale offshore CO₂ storage project was performed in a geological deep aquifer in the Pohang Basin, Korea for a technological development of large-scale CO₂ storage. A challenging issue in the early design stage of the project was to establish the proper injectivity during CO₂ injection. To solve this issue, injection conditions were calculated by calculating injection rate, pressure, temperature, CO₂ phase change, and thermodynamic properties. For this study, we simulated and numerically analyzed CO₂ phase change from gas to supercritical phase and flow behavior in transport piping and injection tubing using OLGA program. Our results provide the injectivity conditions of CO₂ injection system combined with a bottomhole pressure of an aquifer.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.170-174
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• 2011

홍수시 저수지 상류로부터 유입되는 다량의 오염물, 협잡물은 저수지의 경관 및 수질에 악영향을 미친다. 이러한 오염물질은 홍수시 일시에 유입되어 표층에 부유하므로 수거를 위한 시간 및 비용이 비교적 크게 발생된다. 따라서 이러한 부유쓰레기를 효과적으로 차단할 수 있는 시설물 설치는 필연적이다. 이렇게 부유쓰레기 수거를 위한 방법 중, 저수지 내부에 선 차단 시설을 설치하여 부유쓰레기를 홍수터로 유도하여 수거하는 방법은 일시에 많은 양의 부유쓰레기를 차단하게 되는데 유지관리, 경제적 측면에서 유리하다. 본 연구에서는 부유쓰레기 수거를 위한 선 차단시설 운영 방안을 검토하기 위하여 홍수시 저수지 내로 유입되는 유속흐름을 2차원 수치해석 모형인 RMA-2 모형으로 해석하고, 저수지의 내 외부 지형분석을 통하여 시범 지구의 선 차단시설 설치 위치를 선정하였고, 3차원 수치해석 모형인 FLOW-3D 모형으로 검증하였다. 선 차단시설 설치 시범지역 위치 선정을 위하여 저수지의 규모, 접근성, 시공 장비의 대여 편이성 등을 종합적으로 고려하여 기흥저수지를 시범예정 구역으로 선정하였다. 저수지 내로 유입되는 유속특성을 2차원 수치해석 모형인 RMA-2 모형으로 해석하여 시범 지구의 선 차단시설 설치 위치를 제안하고 홍수터 부지를 결정하였다. 부유쓰레기 유도를 위한 선차단시설은 저수지 급확대로 인한 유속 감소구간과 와류발생 구간이 적절한 것으로 분석되었으며 시범설치 지역인 기흥저수지 상류 급확대부에 선 차단시설을 제안하였다. 홍수터의 규모는 Armitage와 Rooseboom(2000)이 제안한 경험식을 바탕으로 $5,300m^2$을 제안하였으며, 기흥저수지 상류부 우안에 항아리 모양으로 설치하도록 계획하였다. 또한, 3차원 수치모형실험을 통하여 검토한 결과, 차단막 설치로 부유 쓰레기의 하류 이송은 차단되고, 원활하게 홍수터로 유도됨을 확인하였다.

• Economic and Environmental Geology
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• v.41 no.1
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• pp.151-163
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• 2008

Since the country's opening to the world, China's rapid economic growth has resulted in strong demand for a wide variety of mineral commodities. During the same period, China's mineral production increased sharply. China's increased mineral production and demand affected the worldwide availability of minerals and metals, the market prices, and trade. Ministry of Land and Resources of China (MLR) planned to build as many as 10 strategic mineral reserve, including reserves of aluminium, copper, manganese, uranium, and other mineral that the country urgently needed. In white paper of China's mineral resources, China is planning the mineral resources conservation and its reasonable utilization, domestic supply increase of resources, activation of cooperative development with foreign partners, balance in resources development and environment conservation, and sustainable resources management as the mineral resources policies for the China's economic development.

• Journal of Korean Society of Forest Science
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• v.80 no.1
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• pp.72-81
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• 1991

This study was carried out to provide necessary information for improving quarrying industry management in Korea. The results of the study are summarized as follows : 1. In aggregate and building-stone quarrying firms the managers over 40 years of age are 97% and 89.1%, the ones above education level of high school are 90% and 85% and the ones not more than 10 years of quarrying experience are 70% and 52%, respectively. Accordingly it can be pointed out that most of the managers of two types of firms are relatively old, have high educational background, while quarrying experiences of building-stone firm managers are longer than that of aggregate firm managers. 2. Most of the management forms are social corporation(60%) for aggregate quarry firms and private management(76%) for building-stone firms. Average areas of permitted stone-pits of aggregate and building-stone quarries are about 2.86ha and 1.66ha respectively. That is, aggregate quarrying firms are carried on a larger scale than building-stone quarrying firms. 3. The yearly average product of aggregate quarrying firms has increased steadily from $88.961m^3$ in 1985 to $144.028m^3$ in 1988, while, in case of building-stone quarry firms, it has significantly increased from $4.155m^3$ to $19.462m^3$ from 1985 to 1987, but reduced to $13.400m^3$ in 1988. Unstable production activities of building-stone quarrying firms may require continuous government support. 4. Major cost items are equipment rental, depreciation, salaries, repair, maintenance for aggregate quarrying firms, and salaries, depreciation, fuel, tax for building-stone quarrying firms. The yearly average rate of return is about 9.7% for aggregate quarry firms and 2.6% for building-stone quarry firms. It can be pointed out that aggregate quarrying firms is better managed than building-stone quarrying firms. 5. The production elasticity of salary for aggregate quarrying firms is 0.495, that of employees is 0.559, and that of capital service is 0.513. The sum of the elasticities is 1.257>1. Fur building-stone quarrying firms, that of employees is 0.492, that of variable costs is 0.192, and that of capital service is 0.498. The sum of elasticities is 1.172>1, thus denotes the increasing returns to scale for both types quarrying firms. 6. The ratio of marginal value product to opportunity cost of empolyees is 2.54, that of variable costs is 3.62, and that of capital service is 1.45, in aggregate quarrying firms. That of employees is 2.47, that is variable costs was 2.34, and that of capital service is 19.67 in building-stone quarrying firms. Therefore the critical factors for more expansion of management scale in aggregate quarrying firms are variable cost and employees, and are capital service in building-stone quarry ing firms. 7. The break-even points of stone sales are about 0.587 billion won and 0.22 billion won in aggregate and building-stone quarrying firms respectively. The optimum sales Level for profit maximization are about 2.0 billion and 0.5 billion in aggregate and building-stone quarry firms respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.320-320
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• 2012

수문학적 의미의 일반적인 물순환은 증발, 응결, 강수 등 태양에너지와 중력에 의해 전지구적으로 반복되는 물의 재생산과정을 의미한다. 최근 들어 토목분야에서 언급되기 시작한 물순환시스템은 수문학적인 물수지(water balance)에 저류, 공급, 처리, 재이용 등 인공적인 요소를 감안하여 대상지역의 적절한 수요, 공급을 유지하는 시스템을 의미한다. 생활에서 물이 차지하는 중요성을 감안할 때, 지역의 수문학적 특성과 문화, 경제적 여건을 고려한 효율적인 물순환시스템의 구축은 지역발전의 정도를 가늠할 수 있는 지표라 할 수 있다. 본 연구는 물산업 선진국인 영국과 미국의 지역 물순환시스템 설계사례를 조사하고 초기단계인 국내사례와 비교하여 향후 설계지침 개발의 기초자료로 활용하기 위하여 수행되었다. 선진사례 조사는 2009년 이후 미국과 영국에서 수행된 세 건의 물순환 현황조사(water cycle study)와 미국에서 개발된 설계최적화 프로그램을 분석하였고, 국내사례로는 파주운정지구와 광교신도시 개발 시 수행된 물순환시스템 구축사례를 조사하였다. 해외 선진국 사례조사 결과, 물순환시스템 구축은 공통적으로 물순환망 현황조사, 물순환 계획수립, 지역현황 조사, 적용가능 기술조사, 설계 등 5단계를 거쳐 수행되었다. 이 중 가장 중요한 단계는 지역의 물수지와 가용 물 수요 및 공급 시스템을 조사하는 물순환망 현황조사로, 지역의 needs를 정확히 파악하고 양적, 질적 공급목표를 적절하게 선정하여 가장 효율적인 물순환망 계획을 수립하는 바탕이 되었다. 지역현황은 지역 법규 및 투자계획, 사회변화 예측 등 사회적 요소를 고려하는 단계로, 물순환 설계 선진사의 설계 최적화 프로그램의 경우 이러한 지역현황과 사회적 변화 예측의 반영에서 차별성을 갖고 있었다. 적용가능 기술조사의 경우 친환경, 저에너지 기술이 부각되던 추세에서 최근에는 지속가능성이 주요 고려사항 이었다. 국내사업 사례의 경우 규모가 작아 직접적인 비교가 불가하였으나, 5단계의 복잡한 최적화단계가 아닌 물순환망 분석결과와 이해당사자(stakeholders)의 needs를 바탕으로 치수안정성, 친수환경 보장 등의 목표를 수립하였다. 국내에서도 향 후 유역규모(watershed scale)의 대형 물순환기반 복합개발사업이나 대규모 해외사업 참여 시 필요한 기술력 축적의 차원에서 단계별 check list를 포함한 한차원 높은 물순환 설계지침 마련이 필요한 시점이라 하겠다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.275-284
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• 2021

Survival analysis was used to analyze whether there is a difference in the effect of leverage on corporate failure according to the firm size. A total of 25,250 (year-company) companies listed on the Korea Stock Exchange and KOSDAQ market from 1999 to 2019 were analyzed. First, the increase in leverage generally acts as a factor that increases the possibility of corporate failure. On the other hand, the increase in the trade payable ratio lowered the possibility of failure of the company. The increase in corporate trade payable was perceived as a factor in reducing the possibility of corporate failure because it was considered the active development of business activities or active use of interest-free debt rather than leading to an increase in corporate risk. Second, a higher leverage ratio and trade payable ratio in large firms lowered the possibility of corporate failure. In the SMEs, all types of leverage increases are a factor that increases corporate failure. Overall, the effect of leverage on corporate failure differs according to the size of the company.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.559-568
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• 2017

recent times, the monthly rent in the Jongno-gu Historical and Cultural Street in Seoul has rapidly increased, because of the presence of large-scale franchises and the entry of private investment into the traditional and local businesses focusing on Bukchon, Seochon, Insa-dong, and Samcheong-dong. As a result, the business environment for these merchants has worsened, due to the increasing economic burden. In order to maintain the business environment of the merchants, it is necessary to evaluate the potential for establishing a regional commercial area, in order to resolve the problems of the existing commercial areas and to improve the locational, economic, cultural and political environment. This study analyzed the factors influencing the merchants' satisfaction with the business environment as a function of their age, by considering three age groups, viz. 30-49, 50-59, and more than 60, considering the locational, economic, cultural and political environment of the merchants. Among the factors influencing the satisfaction with the business environment, the merchants in their 30s and 40s placed more emphasis on the traffic accessibility, floating population, store premium and monthly rent than the other age groups. Among the factors influencing the satisfaction with the business environment, the merchants in their 50s placed more emphasis on the cultural organization, artist activities, expansion of community support facilities, and banning of franchises in certain locations than the other age groups. Among the factors influencing the satisfaction with the business environment, the merchants over 60 years old placed more emphasis on the walking accessibility, monthly sales, merchant community, preservation of historical and cultural landscape, and commercial protection of the government than the other age groups.