• 환경영향평가
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• 제32권6호
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• pp.488-502
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• 2023

생태계서비스 계정은 생태계 공급 기능과 수요, 그리고 그 사이에서 발생하는 실제 서비스 흐름을 측정해야 한다. 흐름을 측정하기 위해서는 공급과 수요 관계를 정의해야 하며, 복잡한 연결 관계를 객관화 할 수 있는 방법론이 필요하다. 국내에서는 생태계서비스에 대한 연구가 다양하게 진행되어 왔으나, 생태계서비스 계정화에 관한 연구는 부족하다. 본 연구의 목적은 환경경제통합계정(SEEA)의 실험적 생태계계정(EEA)에서 연구된 EU 방법론을 적용하여 홍수조절 생태계서비스를 평가하고 이를 토대로 생태계 계정 도입 방안을 모색하는데 있다. 연구수행을 위해 생태계의 유출량 보유 잠재력, 홍수조절에 대한 사회·경제적 수요, 그리고 그 사이의 관계로부터 형성되는 실제 서비스 혜택 흐름을 공간 기반으로 모델링하고 정량화하였다. 홍수조절 생태계서비스 실제 흐름을 산정한 결과, 국내 전체 서비스량은 165,595ha로 산출되었으며 많은 부분이 농경지에 집중되고 있음을 확인할 수 있었다. 향후 국내 홍수조절 서비스 계정 정밀화 도입을 위해서는 토지피복도와 같은 핵심 공간자료가 지속해서 구축 관리되어야 하며, 국가, 지역, 유역 등 다양한 공간 범위에서 적용 가능한 입력자료 및 방법론에 대한 연구가 필요할 것으로 보인다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.198-201
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• 2009

As a way to improve the safety of automotives and to reduce the weight of vehicles, new forming technologies and advanced materials are in high demand in the automotive industry. However, the advanced strength steel has inferior formability and large springback. In order to overcome such drawbacks, the hot press forming process (HPF) has been being applied for forming of automotive sheet parts. In this work, new equipment was suggested to measure unlimited displacement range compared to previous one which was able to measure only up to 10mm displacement range. The external extensometer connected with grips by wire was applied to equipment so that total strain range was measured up to failure also in high temperature. And the finite element analysis was conducted to characterize the mechanical properties of the HPF steel. Finally, the flow curves were represented by utilizing the Johnson-Cook type equation both in uniform and post-uniform deformation regions.

• 한국정밀공학회지
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• 제29권8호
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• pp.834-839
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• 2012

Recently, mechanical components with miniaturized size, complex shape and fine surface are on demand from industries such as mobile electronics, medical devices and defense. The size of them is smaller than several millimeters, the shape has micro-holes, curve, or multi-step and the surface is mirror-like. This features are not able to be machined with the conventional machining, therefore electro-discharge machining (EDM), cutting, and laser machining have been applied. If the technologies are assisted by vibration, high aspect ratio and good surface are to be achieved. In this paper, prior and current researches of vibration-assisted machining are reviewed. Machining mechanisms with vibration-assisting are explained, their effects are shown, and vibrating apparatuses are discussed. Especially, comparison between with and without vibration assisting is presented. This review shows the vibration-assisted machining is effectively fabricate the components with small and complicated shape and fine surface finish.

• Structural Engineering and Mechanics
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• 제33권2호
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• pp.239-255
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• 2009

In the companion paper, a simple but effective analysis procedure termed an Improved Modal Pushover Analysis (IMPA) is proposed to estimate the seismic capacities of multi-span continuous bridge structures on the basis of the modal pushover analysis, which considers all the dynamic modes of a structure. In contrast to previous studies, the IMPA maintains the simplicity of the capacity-demand curve method and gives a better estimation of the maximum dynamic response in a bridge structure. Nevertheless, to verify its applicability, additional parametric studies for multi-span continuous bridges with large differences in the length of adjacent piers are required. This paper, accordingly, concentrates on a parametric study to review the efficiency and limitation in the application of IMPA to bridge structures through a correlation study between various analytical models including the equivalent single-degree-of-freedom method (ESDOF) and modal pushover analysis (MPA) that are usually used in the seismic design of bridge structures. Based on the obtained numerical results, this paper offers practical guidance and/or limitations when using IMPA to predict the seismic response of a bridge effectively.

• 한국환경복원기술학회지
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• 제17권4호
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• pp.69-79
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• 2014

Coastal wetlands are among the most productive biomes in the Earth. The economic values include the direct use of a coastal wetland's ecosystem services, such as food, raw materials, recreation, and tourism. Other values comprise the indirect use of a coastal wetland's ecosystem services, such as carbon sequestration, waste-water treatment, and erosion prevention. In particular, Suncheon Bay is recently attracting attention as the most successful case of the preservation and restoration. This study applies Travel Cost Method (TCM) to estimate the economic value by drawing the demand curve for trips to Suncheon Bay. The TCM is an approach used for economic valuation of non-market goods and services. Based on the results of TCM, this study shows that the economic benefit from recreational uses of the site adds up to \174.7 billion per year. It is also significant in the sense that monetary information is suggested to help local policy makers evaluate the realistic values of coastal wetlands.

• 소성∙가공
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• 제20권3호
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• pp.193-205
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• 2011

Because of its rustproof property, stainless steel is widely used in kitchen appliances, building materials, electronics, chemical plants and automobile exhausts. In addition, the utilization of stainless steel for fuel cell application is growing. As the demand for this material increases, it is necessary to study the basic properties of stainless steel such as corrosion resistance, heat transfer, formability, cutting or shearing ability and weldability. In this article, the mechanical properties, formability and press forming performance of stainless steel are reviewed. Since temperature and strain rate affect the press forming performance of STS304(austenitic) stainless steel, the influence of these parameters on the plastic behavior should be investigated. Moreover, measures for the prevention of ridging of STS430(ferritic) and delayed fracture of STS430, which respectively appear during and after press forming, should be considered. Recently, stainless steel sheets with a thickness lower than 0.2 mm have been widely used in applications for mobile phone, digital camera and fuel cell separator. Therefore, there is a growing interest of studying the grain size effect and plasticity at the crystal scale in order to understand the anisotropic behavior and micro forming ability of thin sheets. This review paper was written with the objective of helping engineers and researchers to understand the forming characteristics of stainless steel and to establish standards in plastic forming techniques.

• 한국기술혁신학회:학술대회논문집
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• 한국기술혁신학회 2001년도 추계학술대회
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• pp.37-57
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• 2001

Digital technology enhanced the improvement of technological aspects in the both broadcasting and telecommunications industries. The infrastructures of each industry converged to one, which impacts not only on technology but also on the broadcasting service. The current broadcasting service is characterized by one-way service, but it'll changed to be customized, or two-way service that reflects the interest of customers. This change requires a new standard to categorize and analyze the future broadcasting service converged and market structure, differing from the present standard based on the transmission channels. This study aims at forecasting the demand of interactive TV service as a representative broadcasting service in the near future, and analyzing the market structure of the broadcasting services. We assume that the present broadcasting and information and telecommunications services such as terrestrial, cable TV, satellite, digital TV services and high-speed broadband service have strong relationship with interactive TV service. First we use Bass diffusion method to predict the diffusion curve of the present five services. Then we analyze the relationship between the present services and interactive TV service by Delphi method. Finally we estimate the potential subscription number of interactive TV service based on the relationship among the services and diffusion parameters.

• Earthquakes and Structures
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• 제4권2호
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• pp.157-179
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• 2013

Vulnerability studies on the existing building stock require that a large number of buildings is analyzed to obtain statistically significant evaluations of the seismic performance. Therefore, analytical evaluation methods need to be based on simplified methodologies of analysis which can afford the treatment of a large building population with a reasonable computational effort. Simplified Pushover-Based Earthquake Loss Assessment approach (SP-BELA), where a simplified methodology to identify the structural capacity of the building through the definition of a pushover curve is adopted, was developed on these bases. Main objective of the research work presented in this paper is to validate the simplified methodology implemented in SP-BELA against the results of more sophisticated nonlinear dynamic analyses (NLDAs). The comparison is performed for RC buildings designed only to vertical loads, representative of the "as built" in Italy and in Mediterranean countries with a building stock very similar to the Italian one. In NLDAs the non linear and degrading behaviour, typical of the structures under consideration when subjected to high seismic loads, is evaluated using models able to capture, with adequate accuracy, the non linear behaviour of RC structural elements taking into account stiffness degradation, strength deterioration, and pinching effect. Results show when simplified analyses are in good agreement with NLDAs. As a consequence, unsatisfactory results from simplified analysis are pointed out to address their current applicability limits.

• KIEE International Transactions on Power Engineering
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• 제5A권4호
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• pp.331-338
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• 2005

In this paper, an improved maintenance scheduling approach suitable for the competitive environment is proposed by taking account of profits and costs of generation companies and the formulated combinatorial optimization problem is solved by using Reactive Tabu search (RTS). In competitive power markets, electricity prices are determined by the balance between demand and supply through electric power exchanges or by bilateral contracts. Therefore, in decision makings, it is essential for system operation planners and market participants to take the volatility of electricity price into consideration. In the proposed maintenance scheduling approach, firstly, electricity prices over the targeted period are forecasted based on Artificial Neural Network (ANN) and also a newly proposed aggregated bidding curve. Secondary, the maintenance scheduling is formulated as a combinatorial optimization problem with a novel objective function by which the most profitable maintenance schedule would be attained. As an objective function, Opportunity Loss by Maintenance (OLM) is adopted to maximize the profit of generation companies (GENCOS). Thirdly, the combinatorial optimization maintenance scheduling problem is solved by using Reactive Tabu Search in the light of the objective functions and forecasted electricity prices. Finally, the proposed maintenance scheduling is applied to a practical test power system to verify the advantages and practicability of the proposed method.

• 노동경제논집
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• 제27권1호
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• pp.165-179
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• 2004

일반적으로 비교되는 임금상승률과 노동생산성증가율은 임금상승률과 평균노동생산성증가율의 비교라는 데에 문제가 있다. 이를 극복하기 위해 본고는 새로운 비교 방법을 제시한다. 대체탄력성과 기술수준을 추정한 후 한계노동생산성을 추정하여 이것의 증가율과 임금상승률을 비교하는 것이다. 우리나라 자료를 사용하여 이러한 방법으로 비교하면 임금과 한계노동생산성은 1963~2000년 동안 전반적으로 유사하다는 것을 알 수 있다. 그러나 1987년을 기점으로 기간을 나누어 보면 이전에는 임금이 한계노동생산성에 못 미치나, 이후에는 임금이 한계노동생산성을 상회한다. 임금상승률이 한계노동생산성증가율과 큰 차이가 없더라도 평균 노동생산성증가율과는 괴리할 수 있다. 따라서 임금상승률이 평균 노동생산성증가율을 초과한다고 해서 노동의 수요곡선을 벗어난 과도한 임금인상이라고 말할 수 없다.