• 한국융합학회논문지
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• 제10권11호
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• pp.321-326
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• 2019

대중교통의 이용량이 증가해 감에 따라 그 중 자동차의 연비를 올리기 위하여 많은 연구들이 수행되고 있다. 본 연구의 목표는 자동차의 3가지 모델을 통해 자동차의 연비를 높일 수 있기 위하여 전방 차체를 설계하고자 하는 것이다. 모든 모델들은 CATIA 프로그램으로 설계되었고 ANSYS 프로그램으로 자동차의 외부 공기에 대한 유동해석을 모델별로 수행하였다. 시속 90km/h의 운행 속도에서는 차체가 길쭉할수록 공기의 저항을 덜 받아 연비를 높일 수 있는 효과가 있다고 사료된다. 본 연구를 통하여 기차의 효율성을 극대화할 수 있는 자동차의 전방 차체를 설계하는데 도움이 될 수 있다. 본 연구에서의 자동차 내부에 있는 라디에이터 위치에 따른 유동 해석에 관한 설계 데이터를 이용함으로서 실제적인 자동차에서의 부품에 융합하여 그 미적 감각을 줄 수 있다.

• 한국정보통신학회논문지
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• 제23권8호
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• pp.950-958
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• 2019

공유경제의 등장은 디지털 기술을 사회혁신에 활용하는, 디지털 사회혁신을 사회문제의 새로운 해결책으로 주목 받게 하고 있다. 그런데 또 한편으로는 부스러기 공유경제, 주문경제처럼 디지털 기술의 부정적 영향을 우려하는 목소리도 있다. 본 연구는 디지털 사회혁신에 의해 창출되는 가치의 성격과 원천 그리고 작동방식을 밝힘으로써 제기된 의문과 우려에 대한 답을 구해보고자 한다. 먼저 사회혁신이 창출하는 비즈니스 가치의 성격과 원천에 대해 논의하고 디지털 기술에 의해서 창출되는 비즈니스 가치의 성격과 원천을 검토한다. 기부, 연대, 공유라는 사회혁신 활동 창출 가치의 원천, 그리고 디지털 기술이 만들어내는 가치의 원천인 효율성과 효과성을 알아보고 소비자/사용자의 역할을 논의한다. 실제 디지털 사회혁신 성공사례인 행복주차골목 리빙랩의 비즈니스 모델 분석을 통해 창출되는 가치들이 실제 현장에서 어떤 방식으로 발생하고 구현되는지 알아본다.

• 한국융합학회논문지
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• 제10권5호
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• pp.181-188
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• 2019

ICT기술을 기반으로 공유경제 서비스시스템을 사람들이 손쉽게 사용할 수 있다. 대부분의 공유경제 서비스는 민간기업에서 제공하고 있으며, 공공재에서의 논의는 미진하다. 현재 진행되는 공유경제 서비스를 택배서비스 관점에서 본다면 우버의 시스템이 대안이 될 수 있다. 우체국의 택배서비스는 ICT기술을 이용하지만 공유경제의 서비스와는 차이가 있다. 본 연구는 델파이 분석기법과 AHP방법론을 사용하여, 공유경제 시스템을 도입하는데 있어서 중요요인들을 도출하였다. 그 결과 상위계층에서는 사회경제적 특성이 가장 중요한 것으로 나타났으며, 하위계층에서는 공유경제 플랫폼, 유휴자원의 공유, 스마트폰의 대중화, 전자상거래의 증가가 4가지 중요 요인임을 알 수 있었다. 이 연구를 통해서 공유경제의 본질인 '효율의 극대화'를 위해서 공공재에 공유경제 시스템에 도입의 필요성과 도입 시 중요요인에 대해서 제시하고 있다.

• International Journal of Computer Science & Network Security
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• 제21권3호
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• pp.198-205
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• 2021

For twenty years, in the EU there has been a trend of a lack of maritime infrastructure and a redundance of the road one, which has a negative impact on the economy. The intermodal transport market structure in the EU has not changed over the past ten years. The stability of transport systems due to the lack of changes in the transport market remains under threat, affecting supply chains and networks through the optimization of warehousing and transportation costs. The research methodology is based on a quantitative assessment of cause-and-effect relations between economic growth and transport and logistics in the EU. A statistical analysis of security indicators, intermodal and modal transport, international trade in goods within the EU and in the world trade in goods, the dynamics of GDP of the EU countries, the level of openness of the EU economy, investment and maintenance costs of different modes of transport and infrastructure has been carried out. The results show that in 2000- 2010 there were positive changes in the transport and logistics infrastructure of the EU, which had a positive effect on trade, openness of the economy of the EU, GDP growth. However, at that time, negative effects of environmental impact and the load on road and rail transport were accumulating. Investment in different modes of transport is limited, and technical maintenance and infrastructure maintenance costs form a significant part of GDP of the EU. A slowdown in economic growth leads to budget constraints and infrastructure financing gap. As a result, the freight and passenger intermodal and modal transport market structure remains virtually unchanged. The load on rail and road transport remains stable, despite the reduced level of transport hazards. Transport productivity has declined over the past ten years. Herewith, the intensification of trade and the openness of the EU economies require constant modernization and innovative renewal. The EU policy in this direction remains normative, uncontrolled, which is reflected in investment differences within the EU and maintenance costs.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.95-95
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• 2010

In recent, there are tremendous requirements to improve the fuel economy of vehicle. For satisfaction of requirements, Hybrid Electric Vehicle or other technologies are suggested and implemented. However, it should be noted that almost 35% energy loss is occurred in the shape of exhaust gas as ever. For increase the efficiency of vehicle, it is certain that the exhaust gas energy should be recover, and generate energy. In previous studies, the technologies such as turbo-compound, thermoelectric and rankine cycle are suggested to recover the exhaust heat energy in vehicle. But, they focus on the conventional vehicle or parallel Hybrid Electric Vehicle. Series Hybrid Electric Vehicle has advantage that the engine and drive shaft are de-coupled. It means that the engine can be operated in high efficiency area regardless with vehicle states. Therefore, if rankine cycle is applied to series hybrid electric vehicle, operating condition of that becomes almost steady. So, in this study, theoretical analysis on the efficiency of rankine cycle applied to series hybrid electric city bus is carried and the energy recovered from exhaust gas during vehicle drive cycle is calculated.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.105-112
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• 2013

In this paper, EV (Electric Vehicle) and ICE (Internal Combustion Engine) vehicle simulators are developed to compare maximum driving range of EV and ICE vehicle according to different driving patterns. And, simulations are performed for fourteen constant velocity cases (20, 30, 40, ${\ldots}$, 150 km/h) and four different driving cycles. From the simulation results of constant velocity, it is found that the decreasing rate of maximum driving range for EV is larger than the one for ICE as both the vehicle velocity and the driving power increase. It is because the battery efficiency of EV decreases as both the velocity and the driving power increase, whereas the engine and transmission efficiencies of ICE vehicle increase. From the results of four driving cycle simulation, the maximum driving range of EV is shown to decrease by 50% if the average driving power of driving cycle increases from 10 to 20kW. It is because the battery efficiency decreases as the driving power increases. In contrast, the maximum driving range of ICE vehicle also increases as the average driving power of driving cycle increases. It is because the engine and transmission efficiencies also increase as the driving power increases.

• 한국분무공학회지
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• 제25권2호
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• pp.45-50
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• 2020

Recently, global warming and environmental pollution are becoming more important, and fuel economy is becoming important. Each automobile company is actively developing various new technologies to increase fuel efficiency. CVVD(Continuously Variable Valve Duration) system means a device that continuously changes the rotational speed of the camshaft to change the valve duration according to the state of the engine. In this paper, VVT(Variable Valve Timing) and CVVD were applied to a single-cylinder diesel engine, and the characteristics of intake and exhaust flow rate and in-cylinder pressure characteristics were analyzed by numerical analysis. In order to analyze the effect of CVVD on the actual engine operation, the study was performed by setting the valve control and injection pressure as variables in two sections of the engine operating region. As a result, In the case of applying CVVD, the positive overlap with the exhaust valve is maintained, thus it is possible to secure the flow smoothness of air and increase the volumetric efficiency by improving the flow rate. The section 2 condition showed the highest peak pressure, but the pressure rise rate was similar to that of the VVT 20 and CVCD 20 conditions up to 40 bar due to the occurrence of ignition delay.

• 한국태양에너지학회 논문집
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• 제29권5호
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• pp.8-13
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• 2009

Feasibilities of the application of a micro gas turbine cogeneration system to a large size hospital building are studied by estimating energy demands and supplies. The energy demand for electricity is estimated by surveying and sorting the consumption records for various equipment and devices. The cooling heating, and hot water demands are further refined with TRNSYS and ESP-r to generate load profiles for the subsequent operation simulations. The operation of the suggested cogeneration system in conjunction with the load data is simulated for a time span of a year to predict energy consumption and gain profile. The simulation revealed that the thermal efficiency of the gas turbine is about 30% and it supplies 60% of the electricity required by the building. The recovered heat can meet 56% of total heating load and 67% of cooling, and the combined efficiency reaches up to 70%.

• 한국자동차공학회논문집
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• 제15권3호
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• pp.183-188
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• 2007

Recently, diesel engine has been frequently applied to RV, SUV and light duty truck due to the good fuel economy and high thermal efficiency. $NO_x$ and PM, environmental pollution materials are basically produced in diesel combustion process. The most important target in diesel engine research is the development of system to reduce the emissions of $NO_x$ and PM. Cooled EGR system is an effective method for the reduction of $NO_x$ emission and PM emission from a diesel engine and EGR cooler is the key component of the system. This study investigates the EGR cooler of oval gas tubes compared with the EGR cooler of shell & tubes to verify the heat exchange efficiency of cooler by means of engine dynamometer tests, rig performance tests and numerical analyses.

• 아태비즈니스연구
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• 제10권2호
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• pp.1-12
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• 2019

Collaborative research and development (R&D) has been encouraged based on the belief that knowledge spill-over is mutually beneficial for partners. Although the benefits are supported by science and technology policy research, the risk of R&D collaboration has not been extensively discussed. Two independent studies suggest that there are risks associated with the overuse of collaborative research frameworks. Two sets of R&D collaboration data were analyzed: between the national bio-technology research program and 1) Data Envelop Analysis (DEA), and 2) between Stochastic Frontier Analysis (SFA). In the case of SFA, output measures were integrated into a single output, with weights extracted from research programme managers' responses to the questionnaire. While the DEA result demonstrated the inefficiency of collaborative research, SFA did not. Unlike previous research highlighting risks associated with disclosing proprietary R&D and potential conflict of interest, our study indicates that the transaction's social cost affects collaborative research efficiency. Therefore, governments promoting R&D collaborations should be carefully managed, and policy makers must reconsider the strict conditions governing compulsory collaborative R&D programs.