• 한국철도학회논문집
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• 제16권2호
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• pp.79-84
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• 2013

정거장 또는 차량기지 구내에서 이루어지는 입환은 국내 관련 법규에서 정의, 구분 및 방법이 명확하게 제시되어 있지 않다. 이로 인하여 입환시 충돌사고가 철도차량운전사고 중 가장 빈번하게 발생하고 있다. 따라서 입환 운전시 충돌사고를 줄이면서 효율적인 운영을 위해서는 체계적인 철도차량 안전운전 원칙의 제시가 필요하다. 입환시 충돌사고를 줄이기 위한 연구의 일환으로서, 본 연구에서는 열차운전방식과 입환의 특징을 비교하고, 열차안전운전원칙에 따른 구내운전 안전원칙을 제시하였다. 새로 제안 된 접근 방법은 안전과 효율성의 개선 분석 및 현장 응용 프로그램에서 확인하였다.

• 한국유체기계학회 논문집
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• 제18권1호
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• pp.37-43
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• 2015

A Beta-type Stirling engine is developed and tested on the operation stability and cycle performance. The flow rate for cooling water ranges from 300 to 1500 ml/min, while the temperature of heat source changes from 300 to $500^{\circ}C$. The internal pressure, working temperatures, and operation speed are measured and the engine performance is estimated from them. In the experiment, the rise in the temperature of heat source reduces internal pressure but increases operation speed, and overall, enhances the power output. The faster coolant flow rate contributes to the high temperature limit for stable operation, the cycle efficiency due to the alleviated thermal expansion of power piston, and the heat input to the engine, respectively. The experimental Stirling engine showed the maximum power output of 12.1 W and the cycle efficiency of 3.0 % when the cooling flow is 900 ml/min and the heat source temperature is $500^{\circ}C$.

• 전력전자학회논문지
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• 제24권1호
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• pp.40-48
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• 2019

Hybrid electric propulsion systems (H-EPSs) are an intermediate step for integrated full electric propulsion warships. H-EPSs are a dynamic combination of mechanical and electrical propulsion systems to achieve the required mission performances. The system modes could adapt to meet the requirement of the various operation conditions of a warship. This paper presents a configuration and operating modes of H-EPSs considering the operation conditions of a destroyer class warship. The system has three propulsion modes, namely, motoring mode, generating mode [power take off (PTO) mode], and mechanical mode. The PTO mode requires a careful fuel efficiency analysis because the fuel consumption rate of propulsion engines may be low compared with the generator's engines depending on the loading power. Therefore, the calculation of fuel consumption according to the operating modes is performed in this study. Although the economics of the PTO mode depends on system cases, it has an advantage in that it ensures the reliability of electric power in case of blackout or minimum generator operation.

• 한국항공운항학회지
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• 제30권4호
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• pp.132-144
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• 2022

In response to the recent surge in aviation demand, major airport and aviation authorities continue to make efforts to formulate arrival procedures that take into account efficient aircraft separation, noise and environmental issues related to carbon (CO₂) emissions. In order to ensure efficient traffic control and environmental issues, as a result, a new concept Trombone, Point Merge, etc. have been introduced and widely used. However, these new concept incisions are becoming a factor that hinders operational efficiency and stability due to the restricted domestic airspace such as military airspace and excessive constraints of altitude, speed, etc. which do not reflect the concept of continuous descent operation and eventually needs to be modified to make continuous descent operation as feasible as possible. We herewith analyze and propose the way of improving flight safety and efficiency in the arrival operation procedure by supplementary modification which consequently contribute to the aviation industry international competitiveness.

• 정보학연구
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• 제6권4호
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• pp.125-134
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• 2003

본 논문은 통신 네트워크 운용 효율화를 위해 네트워크 운용요소별 상관관계를 분석하고 기본 모형을 구축하여 민감도 측정 방법을 제안하였다. 통신사업자는 연도별/부문별로 각각 그에 합당한 네트워크 운용기준을 설정하여 비용을 지출하여 왔으나 시장규모가 폭발적으로 성장하고 성장사업의 주력이 점차 변화하고 있는 상황에서, 적정수준에 대한 파악과 그를 위한 보다 포괄적이고 새로운 분석방법의 개발 및 적용이 요구된다. 전반적이고 포괄적인 관점에서 산출된 네트워크 운용의 적정비용에 대해 품질수준 개선을 위한 요소, 고객만족도 관련 요소 등과의 연계성을 중심으로 평가하고 개선하는 것이 본 논문의 가장 핵심적인 연구이다. 이러한 과정은 네트워크 운용의 가장 큰 부분을 차지하는 것이 품질관련 활동이고 품질관련 활동은 결국 고객만족도로 나타나게 되는 것이기 때문에, 각 요소별 개별적인 변화가 상호간에 미치는 영향을 중심으로 상관관계를 정립하여 민감도 측정을 바탕으로 네트워크 운용비용을 산출하는 것이 바람직한 분석이라 할 수 있다. 따라서, 본 논문에서는 네트워크 운용에 대한 체계적인 모형의 구축 및 효율성 측정을 위한 다양한 시나리오에 따른 민감도 측정을 위한 시스템을 개발하였다.

• 한국태양에너지학회 논문집
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• 제34권5호
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• pp.109-115
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• 2014

The supply rate of renewable energy has been increasing under the influence of an energy scarcity. Government has supported the use of renewable energy by government subsidies. The operation of renewable may not been operating appropriately, although increasing the use of renewable energy. We found out some problems of the operation of renewable energy and offered some improvements. This research proposes the efficient operation method for the solar thermal system, and proposed operation method was compared and evaluated with existing operation strategy after selecting one building installed solar thermal system. Recently, the interest to renewable energy has increased because of the environmental issues and energy crisis. However the utilization of the renewable energy system is low because of the use of renewable energy system and existing renewable energy system independently, although supply rate of renewable system is increasing. Especially, in the case of solar thermal system heating load is not responsible for the load of hot water supply in many cases. Therefore, suggesting efficient operation plans and evaluations of the energy consumption and efficiency of a solar thermal system is needed.

• 한국군사과학기술학회지
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• 제13권5호
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• pp.861-868
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• 2010

As CAS, X-ATK, and INT models considered as the most typical Air-to-Ground operation models in ROKAF are mainly designed as the voice-centered system between aircraft and ground control facilities, it is critical to newly develop the Link-16 based model for the ROK-US combined operation between F-15K, AWACS, M-SAM, and KDX-III equipped with Link-16. Former studies had been limited to the CAS operation, and they had mainly focused on reducing the voice transmission time to exchange the information between each mission step with maintaining existing operation steps. Therefore, this paper makes up the weak point in former studies, thereby designing new Air-to-Ground operation model for CAS, X-ATK, INT mission using Enterprise Architecture OV6c, which enables both aircraft and ground control facilities or between aircraft to obtain the real-time information on the location, identification, armament and the real-time image data through the broadcasting function. Based on the analysis of new operation model, we come to a conclusion that by simultaneously exchanging the information on mission between nodes concerned through the broadcasting function of Link-16. It is possible to cut down superfluous steps among the mission steps, and to reduce the mission time. It is clear that it gives rise to improve the battle efficiency and the decision-making tempo as well as the battlefield situational awareness.

• 벤처창업연구
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• 제6권4호
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• pp.137-152
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• 2011

슘페터식 혁신은 이제 제조, 서비스산업을 넘어 농산업에서도 나타나고 있다. 농산업은 과거 가족농 중심의 단순생산체제를 탈피하여, 생산과 유통 전반으로 기업화되어 가는 경향이 나타나고 있는데, 이는 농산업부분에서의 낮은 생산성과 부가가치를 제고하기 위한 생산방식과 조직형태의 혁신이라고 볼 수 있다. 본 연구는 우리나라 농산업의 새로운 시도로 도입된 농업법인 그중에서도 농업생산법인의 생산성 수준을 파악하고 정책적 시사점을 도출하기 위하여 자료포락방법의 개선된 형태인 부트트래핑 자료포락방법을 활용하여 분석하였다. 본 연구의 주요 발견점은 다음과 같다. 분석대상 농업생산법인 중 효율성 값이 1인 효율적인 법인 수는 18.06%에 불과하며 효율성 값이 0.5 미만인 비효율적인 농업생산법인 수는 기술효율성에서는 30.92%, 순수기술효율성에서는 18.93%, 규모의 효율성에 있어서는 3.32%로 나타나 상당수의 농업생산법인이 비효율적인 상태에서 운영되고 있다. 이러한 분석결과는 농업생산법인이 농산업의 생산성 향상을 위한 방안으로 도입되기는 했지만 실질적 생산성 정도는 저조하다는 것을 의미하는 것으로, 농업생산법인의 생산성 제고를 위한 정책적, 전략적 차원의 개선책이 모색되어야 함을 보여 시사한다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제11B권3호
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• pp.64-69
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• 2001

Energy recovery in the regenerative region is very important when SRM is used in traction drive, This is to reduce en-ergy loss during mechanical braking and/or to have a high efficiency drive during braking To control excitation voltage in motor operation and regenerative voltage in the generator operation in the SRM multi-level voltage control is effective The paper sug-gests multi-level inverter which is useful for motoring and regenerative operation in SRM

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1171-1176
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• 2010

Because of global warming, the new environment energy policy was already announced. The role of Green-railways is increasing in the field of railway. The government announced a policy direction of science & technology basic plan. The field of railway transportation proposed various railway transportation policy and plans. In this paper, I presented technical trend analysis for railway policy and railway operation field. Technical trend analysis at home and overseas are classified into railway industry technology, railway transportation system technology, railway operation efficiency technology, railway logistics technology.