• 한국IT서비스학회지
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• 제19권2호
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• pp.125-138
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• 2020

Currently, subway crowding is estimated by observing a specific point at specific hours once or twice every 1 or 2 years. Given the extensive subway network in Seoul Metropolitan Area covering 588 stations, 11 lines and 80 transfer stations as of 2017, implementing crowding mitigation policy may have its limitations due to data uncertainty. A proposal has recently been made to effectively use smart card data, which generates big data on the overall subway traffic related to an estimated 8 million passengers per day. To mitigate subway crowding, this study proposes two viable options based on data related to smart card used in Seoul Metropolitan Area. One is to create a subway passenger pattern model to accurately estimate subway crowding, while the other is to prove effectiveness of early bird policy to distribute subway demand that is concentrated at certain stations and certain time. A subway passenger pattern model was created to estimate the passenger routes based on subway terminal ID at the entrance and exit and data by hours. To that end, we propose assigning passengers at the routes similar to the shortest routes based on an assumption that passengers choose the fastest routes. In the model, passenger flow is simulated every minute, and subway crowding level by station and line at every hour is analyzed while station usage pattern is identified by depending on passenger paths. For early bird policy, highly crowded stations will be categorized based on congestion level extracted from subway passenger pattern model and viability of a policy which transfers certain traveling demands to early commuting hours in those stations will be reviewed. In particular, review will be conducted on the impact of policy implemented at certain stations on other stations and lines from subway network as a whole. Lastly, we proposed that smart card based subway passenger pattern model established through this study used in decision making process to ensure effective implementation of public transport policy.

• 자원ㆍ환경경제연구
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• 제21권1호
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• pp.129-156
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• 2012

본 연구는 다목적댐 운영을 통한 안정적인 수자원 공급이 국가경제에 기여하는 경제적 파급효과를 분석한다. 분석을 위해 17개 주요 다목적댐이 고려되며, 다목적댐에서 공급되는 수자원을 여름과 겨울로 구분하여 별도의 생산요소로 포함하는 연산가능 일반균형모형(computable general equilibrium model: CGE)을 2007년을 기준연도로 하여 구축한다. 분석 내용은 다목적댐 용수 공급의 양적 측면과 안정적 용수 공급 측면을 구분하여, 전자에 대해서는 수자원 수요 충족에 따른 경제적 파급효과를 분석하고, 후자에 대해서는 수자원 공급의 불확실성 감소에 따른 리스크 프리미엄을 추정한다. 분석 결과, 다목적댐이 운영되지 않을 경우에 수자원을 집약적으로 투입하는 농림수산 및 수도 산업의 생산과 농림수산 산출물이 중간재로 많이 사용되는 음식료 산업의 생산이 크게 감소하는 것으로 나타났으며, 철강과 전기전자 등의 산업들은 대체로 생산이 증가하는 것으로 나타났다. GNP는 벤치마크 해 대비 0.22~0.68% 감소하는 것으로 분석되었다. 한편 리스크 프리미엄은 상대적 위험회피 척도 값을 0.5~3.0의 범위에서 고려할 때 약 40억 원~240억 원의 범위를 갖는 것으로 나타났다.

• 대한원격탐사학회지
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• 제33권5_3호
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• pp.799-807
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• 2017

환경영향평가는 개발사업의 해로운 환경영향 감소를 위해 시행되는 규제적 성격의 제도이다. 그러나 환경가치는 계량화가 어렵고 불확실성이 따르기 때문에 제도 운영의 객관성 및 신뢰성 저하 문제가 지속적으로 지적되어 온 실정이다. 따라서 데이터 기반 환경영향평가제도의 필요성이 점차 높아지고 있는데, 특히 환경영향평가는 특정 지역의 개발에 대한 내용을 담기 때문에 공간정보의 비중이 높아 환경공간정보의 활용 가능성이 높은 분야이다. 또한 사후환경관리제도의 도입에 따라 환경정보의 시계열적 제공 및 활용체계가 요구되고 있다. 본 연구에서는 환경영향평가의 제도적 특징을 통해 정보제공체계의 필요성을 도출하고 기존 환경정보 활용체계를 분석하였다. 그리고 이를 토대로 공신력 있는 환경공간정보 제공방안을 제시하여 환경영향평가제도의 한계점 개선을 위한 정책적 함의를 찾고자 하였다.

• Nuclear Engineering and Technology
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• 제47권1호
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• pp.11-25
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• 2015

The accident at Japan's Fukushima Daiichi nuclear power plant in March 2011, caused by an earthquake and a subsequent tsunami, resulted in a failure of the power systems that are needed to cool the reactors at the plant. The accident progression in the absence of heat removal systems caused Units 1-3 to undergo fuel melting. Containment pressurization and hydrogen explosions ultimately resulted in the escape of radioactivity from reactor containments into the atmosphere and ocean. Problems in containment venting operation, leakage from primary containment boundary to the reactor building, improper functioning of standby gas treatment system (SGTS), unmitigated hydrogen accumulation in the reactor building were identified as some of the reasons those added-up in the severity of the accident. The Fukushima accident not only initiated worldwide demand for installation of adequate control and mitigation measures to minimize the potential source term to the environment but also advocated assessment of the existing mitigation systems performance behavior under a wide range of postulated accident scenarios. The uncertainty in estimating the released fraction of the radionuclides due to the Fukushima accident also underlined the need for comprehensive understanding of fission product behavior as a function of the thermal hydraulic conditions and the type of gaseous, aqueous, and solid materials available for interaction, e.g., gas components, decontamination paint, aerosols, and water pools. In the light of the Fukushima accident, additional experimental needs identified for hydrogen and fission product issues need to be investigated in an integrated and optimized way. Additionally, as more and more passive safety systems, such as passive autocatalytic recombiners and filtered containment venting systems are being retrofitted in current reactors and also planned for future reactors, identified hydrogen and fission product issues will need to be coupled with the operation of passive safety systems in phenomena oriented and coupled effects experiments. In the present paper, potential hydrogen and fission product issues raised by the Fukushima accident are discussed. The discussion focuses on hydrogen and fission product behavior inside nuclear power plant containments under severe accident conditions. The relevant experimental investigations conducted in the technical scale containment THAI (thermal hydraulics, hydrogen, aerosols, and iodine) test facility (9.2 m high, 3.2 m in diameter, and $60m^3$ volume) are discussed in the light of the Fukushima accident.

• 자원리싸이클링
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• 제24권2호
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• pp.69-78
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• 2015

자원수급의 불확실성이 점차 고조되고 있는 글로벌 상황에 능동적으로 대처하기 위해 전 세계적으로 효율적인 자원관리의 필요성이 증대되고 있다. 자원관리 선진국들은 국가차원에서의 지속가능한 자원관리를 유도 및 지원하기 위해 자원이용의 효율성을 극대화하기 위한 법제도 마련 및 산업구조로의 전환을 촉진하고 있다. 한편, 국내의 경우 자원수급과 관련하여 국제환경에 매우 민감한 산업구조를 나타냄에 따라 국가 주도의 자원효율성의 획기적인 제고 방안 마련이 절실히 요구된다. 특히 자원 전과정에서의 자원의 효율적 이용을 위한 단계별 추구해야 할 방향과 구체적 실천방안에 대해 검토가 필요하다. 이에 본 연구에서는 자원 전과정을 크게 생산계와 순환계로 구분하고 이에 따른 단계별 국내 자원관리의 현황 및 문제점, 이를 개선하기 위한 방향성 및 구체적 실천방안을 제시하였다.

• 대한전기학회논문지:전력기술부문A
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• 제49권11호
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• pp.549-557
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• 2000

This study proposes a new numerical analysis method for assessing the outage cost of the composite power system with considering transmission system at load points. The proposed method comes from combination of the expected energy not served curve(EENSC) with the marginal outage cost function obtained at load points. Uncertainty of the outages of the generation and transmission systems was also included in this study. This study can be categorized into three processing parts as like as follows. Firstly, EENSC at load points was developed newly from the composite power system effective load duration curve which has been proposed by the authors. Secondly, this study proposes a new technical method for determining the coefficients of the marginal outage cost functions at load points in the composite power system(Generation and Transmission systems). It is a main key point that the mathematical expression for the marginal outage cost function at a load point is formulated and evaluated using relations between the GNP (or GDP) and the electrical energy demand at the load pint. Finally, the outage cost was calculated in this paper by combining the proposed EENSC with the marginal outage cost function evaluated at each load point. It is another important feature that the average costs for future at load points can be forescasted using the proposed approach. The effectiveness of the proposed new approach is demonstrated by the case studies with the IEEE-RTS.

• 자원ㆍ환경경제연구
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• 제11권2호
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• pp.211-231
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• 2002

This paper summarizes the results of a study that assess how a demand side management (DSM) system addresses key economic and environmental challenges facing in the Korean natural gas sector considering; ${\bullet}$ high discrepancies of seasonal consumption volume and of load factor in unmatured domestic LNG market, ${\bullet}$ unfavorable and volatile international LNG market, imposing with the contestable "take-or-pay" contract terms, ${\bullet}$ low profile of LNG and existence of market barriers against an optimal fuel mix status in the industrial energy sector. A particular focus of this study is to establish an 'extended' DSM system in the unmatured gas market, especially in industry sector, that could play a key role to assure an optimum fuel mix scheme. Under the concept of 'extended' DSM, a system dynamics modeling approach has been introduced to explore the option to maximize economic benefits in terms of the national energy system optimization, entailing different ways of commitments accounting for different DSM measures and time delay scenarios. The study concludes that policy options exist that can reduce inefficiencies in gas industry and end-use system at no net costs to national economy. The most scenarios find that, by the year 2015, it is possible to develop a substantial potential of increased industrial gas end-uses under more reliable and stable load patterns. Assessment of sensitivity analysis suggests that time delay factor, in formulating DSM scenarios, plays a key role to overcome various market barriers in domestic LNG market and provides a strong justification for the policy portfolios 'just in time' (time accurateness), which eventually contribute to establish an optimum fuel mix strategy. The study indicates also the needs of advanced studies based on SD approach to articulate uncertainty in unmatured energy market analysis, including gas.

• Nuclear Engineering and Technology
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• 제48권6호
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• pp.1360-1367
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• 2016

This paper introduces a boron meter with improved accuracy compared with other commercially available boron meters. Its design includes a new fitting function and a multi-detector. In pressurized water reactors (PWRs) in Korea, many boron meters have been used to continuously monitor boron concentration in reactor coolant. However, it is difficult to use the boron meters in practice because the measurement uncertainty is high. For this reason, there has been a strong demand for improvement in their accuracy. In this work, a boron meter evaluation model was developed, and two approaches were considered to improve the boron meter accuracy: the first approach uses a new fitting function and the second approach uses a multi-detector. With the new fitting function, the boron concentration error was decreased from 3.30 ppm to 0.73 ppm. With the multi-detector, the count signals were contaminated with noise such as field measurement data, and analyses were repeated 1,000 times to obtain average and standard deviations of the boron concentration errors. Finally, using the new fitting formulation and multi-detector together, the average error was decreased from 5.95 ppm to 1.83 ppm and its standard deviation was decreased from 0.64 ppm to 0.26 ppm. This result represents a great improvement of the boron meter accuracy.

• 문화경제연구
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• 제21권1호
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• pp.3-20
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• 2018

본 연구는 한국 영화산업의 수직계열화 구조와 배급 및 상영시장의 집중도를 파악하고, 이 두 범주 간의 상호연관성에 대한 통합적인 맥락을 제시하고자 하였다. 한국영화 배급 및 상영시장의 집중성은 규모의 경제를 추구하고 수요의 불확실성을 방어하기 위한 산업 논리의 결과이다. 메이저 배급사는 대작영화에 자원을 집중하고 공급량을 조절함으로써 흥행위험을 방어하려는 경향이 강해지고 있으며, 최대한 많은 스크린을 확보하려는 배급 경쟁에 의해 멀티플렉스 체인의 협상력은 강화되고 있다. 수직결합 기업의 멀티플렉스는 계열관계에 따라 각 배급사의 영화에 차별적인 좌석수를 배정하는 것으로 나타났다. 그러나 수직계열화 기업마다 차별의 정도는 차이가 있으며, 상영 스크린수가 증가할수록 관객의 좌석점유율도 증가하고 있어서, 상영관이 계열관계에 따라 비합리적인 선택을 한다고 보기에는 무리가 있다. 따라서 수직결합구조가 스크린 독과점과 양극화의 원인이라는 일반화하기는 어려우며 유통시장의 집중성을 완화하고 중소영화를 지원하는 정책 방향이 요구된다.

• Ocean Systems Engineering
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• 제9권3호
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• pp.287-328
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• 2019

Comprehensive understanding of the flood risk assessments via frequency analysis often demands multivariate designs under the different notations of return periods. Flood is a tri-variate random consequence, which often pointing the unreliability of univariate return period and demands for the joint dependency construction by accounting its multiple intercorrelated flood vectors i.e., flood peak, volume & durations. Selecting the most parsimonious probability functions for demonstrating univariate flood marginals distributions is often a mandatory pre-processing desire before the establishment of joint dependency. Especially under copulas methodology, which often allows the practitioner to model univariate marginals separately from their joint constructions. Parametric density approximations often hypothesized that the random samples must follow some specific or predefine probability density functions, which usually defines different estimates especially in the tail of distributions. Concentrations of the upper tail often seem interesting during flood modelling also, no evidence exhibited in favours of any fixed distributions, which often characterized through the trial and error procedure based on goodness-of-fit measures. On another side, model performance evaluations and selections of best-fitted distributions often demand precise investigations via comparing the relative sample reproducing capabilities otherwise, inconsistencies might reveal uncertainty. Also, the strength & weakness of different fitness statistics usually vary and having different extent during demonstrating gaps and dispensary among fitted distributions. In this literature, selections efforts of marginal distributions of flood variables are incorporated by employing an interactive set of parametric functions for event-based (or Block annual maxima) samples over the 50-years continuously-distributed streamflow characteristics for the Kelantan River basin at Gulliemard Bridge, Malaysia. Model fitness criteria are examined based on the degree of agreements between cumulative empirical and theoretical probabilities. Both the analytical as well as graphically visual inspections are undertaken to strengthen much decisive evidence in favour of best-fitted probability density.