• 경영과학
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• 제19권2호
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• pp.125-137
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• 2002

The telecommunications market is expanding rapidly and becoming more substitutive. In this environment, demand forecasting is very difficult, yet important for both practitioners and researchers. in this paper, we adopt the modeling approach proposed dy Jun and Park ［6］. The basic premise is that demand patterns result from choice behavior, where customers choose a product to maximize their utility. We apply a choice-based substitutive diffusion model to the Korean mobile telecommunication service market where digital service has completely replaced analog service. In comparison with Bass-type multigeneration models. our model provides superior fitting and forecasting performance. The choice-based model is useful in that it enables the description of such complicated environments and provides the flexibility to include marketing mix variables such as price and advertising in the regression analysis.

• 한국환경성돌연변이발암원학회:학술대회논문집
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• 한국환경성돌연변이발암원학회 2004년도 춘계학술대회
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• pp.82-82
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• 2004

• 한국ITS학회 논문지
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• 제10권5호
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• pp.113-123
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• 2011

최근 온난화 문제가 대두됨에 따라 세계 각국에서 $CO_2$ 배출감소를 위한 여러 가지 규제를 설정하고 있다. 특히 수송부분에서의 $CO_2$ 배출량 감소는 매우 영향력이 크므로 자동차 산업에서도 전기자동차를 비롯한 그린자동차 개발에 대한 관심이 높아지고 있다. 이에 따라 전기자동차 시대 도래 대비를 위하여 전기자동차 보급에 따른 인프라 구축 전략안 및 전력량 수요 예측이 필요하지만, 이의 기반이 되는 전기자동차 수요예측 방법은 소개되어 있지 않고 있다. 따라서 본 연구에서는 선택기반 다세대 확산모형을 이용하여 전기자동차의 수요를 예측하는 방법론을 제시하였다. 전기자동차와 비슷한 성격을 가지는 하이브리드 자동차의 과거 데이터를 이용하여 Bass 모형의 혁신계수와 모방계수를 추정하고 SP(Stated Preference)조사를 통하여 잠재적인 총수요를 추정함으로써 전기자동차의 수요를 년도별로 예측하였다. 또한, 전기자동차가 발전하는 속성 진화에 따른 다세대 확산과정을 모형에 반영하여 보다 정확한 수요예측이 가능하도록 하였다. 본 연구의 수요예측 방법론을 통하여 향후 전기자동차의 시장 점유율을 예측함으로써 전기자동차 보급과 밀접한 관련이 있는 전력수급 및 충전인프라 구축 연구에 활용 될 수 있도록 한다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2022년도 추계학술대회
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• pp.162-163
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• 2022

Maritime transportation is going to transfer to alternative fuels as a result of the worldwide demands toward decarbonization and tougher maritime emissions regulations. Methanol is considered as a potential marine fuel, which has the ability to reduce SOx and CO₂ emissions, reduce climate change effects, and achieve the objective of green shipping. This work proposes and combines the innovative combination system of direct methanol solid oxide fuel cells (SOFC), proton exchange membrane fuel cells (PEMFC), gas turbines (GT), and organic Rankine cycles (ORC) for maritime vessels. The system's primary power source is the SOFC, while the GT and PEMFC use the waste heat from the SOFC to generate useful power and improve the system's ability to use waste heat. Each component's thermodynamics model and the combined system's model are established and examined. The multigeneration system's energy and exergy efficiency are 76.2% and 30.3%, respectively. When compared to a SOFC stand-alone system, the energy efficiency of the GT and PEMFC system is increased by 19.2%. The use of PEMFC linked SOFC has significant efficiency when a ship is being started or maneuvered and a quick response from the power and propulsion plant is required.

• 한국항해항만학회지
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• 제47권2호
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• pp.106-119
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• 2023

Due to global decarbonization movement and tightening of maritime emissions restrictions, the shipping industry is going to switch to alternative fuels. Among candidates of alternative fuel, methanol is promising for decreasing SOx and CO2 emissions, resulting in minimum climate change and meeting the goal of green shipping. In this study, a novel combined system of direct methanol solid oxide fuel cells (SOFC), proton exchange membrane fuel cells (PEMFC), gas turbine (GT), and organic Rankine cycle (ORC) targeted for marine vessels was proposed. The SOFC is the main power generator of the system, whereas the GT and PEMFC could recover waste heat from the SOFC to generate useful power and increase waste heat utilizing efficiency of the system. Thermodynamics model of the combined system and each component were established and analyzed. Energy and exergy efficiencies of subsystems and the entire system were estimated with participation of the first and second laws of thermodynamics. The energy and exergy efficiencies of the overall multigeneration system were estimated to be 76.2% and 30.3%, respectively. The combination of GT and PEMFC increased the energy efficiency by 18.91% compared to the SOFC stand-alone system. By changing the methanol distribution ratio from 0.05 to 0.4, energy and exergy efficiencies decreased by 15.49% and 5.41%, respectively. During the starting up and maneuvering period of vessels, a quick response from the power supply system and propulsion plant is necessary. Utilization of PEMFC coupled with SOFC has remarkable meaning and benefits.