• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1483-1493
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• 2018

Recently, more power facilities are needed to cope with the increasing electric demand. However, the additional construction of generators, transmission and distribution installations is not easy because of environmental problems and citizen's complaints. Under this circumstance, a microgrid system with distributed renewable resources emerges as an alternative of the traditional power systems. Moreover, the configuration of power system changes with more DC loads and more DC installations. This paper is written to introduce an idea of a genetic algorithm-based solution to determine the optimal capacity of the distributed generators depending on the types of system configuration: AC-link, DC-link and Hybrid-link types. In this paper, photovoltaic, wind turbine, energy storage system and diesel generator are considered as distributed generators and the feasibility of the proposed algorithm is verified by comparing the calculated capacity of each distributed resource with HOMER simulation results for 3 types of system configuration.

• 신재생에너지
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• 제10권3호
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• pp.47-54
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• 2014

Recently, BESS is considered as one of essential countermeasure for demand side management. However, an economic evaluation is critical issue for the introduction of power system because the cost of BESS is very high in present stage. Therefor, this paper presents economic evaluation method for customer use case by considering peak shaving function based on the real time price. From the case study on the model power system and educational customer, it is confirmed that the proposed method is a practical tool for the economic analysis of BESS. and analytical approach for the reliability assessment in radially operated distribution systems. The approach can estimate the expected reliability performance of distribution systems by a direct assessment of the configuration of the systems using the reliability indexes such as NDP (Non-Delivery Power) and NDE (Non-Delivery Energy). The indexes can only consider the number and configuration of the load, but can not consider the characteristics of the load which is the one of the most important factor in the investment cost for the distribution systems. Therefore, this paper presents the new performance indexes for the investment of the distribution facilities considering both the expected interruption cost for the load section and the operation characteristics of Energy Storage System. The results from a case study show that the proposed methods can be a practical tool for the reliability management in distribution systems including Energy Storage System.

• 전기학회논문지
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• 제58권7호
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• pp.1270-1275
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• 2009

The structure of a power distribution system will change in a loop configuration such as in the case of a smart grid. If power distribution system changes radial to loop form, the structure may have to be changed significantly. Therefore, we analyzed the reliability indices and calculated a CIC(Customer Interruption Cost) for the loop power distribution system. The power distribution system reliability depends on the protection scheme. This study is applied to the current protection scheme method and is compared with each model. When the CIC was evaluated, most studies performed calculations only for sustained interruptions. However, in actuality, momentary interruption frequencies occurred more than sustain interruptions. Thus, it is occurred the CIC additively. Therefore, we evaluated a CIC including momentary interruption, for each model, and then compared with MAIFI(Momentary Average Interruption Frequency Index)

• 한국기계가공학회지
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• 제12권3호
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• pp.21-27
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• 2013

This study is investigated on flow analysis according to grill configuration of radiator. The stream of flow which pass through radiator grill in car body and the contour of pressure distribution are estimated by the basis. As the magnitude of resistance force which flow affects the car body is investigated so that the power reduction can be reduced. As the pressure inside radiator grill is assessed, more efficiency can be investigated in order that the flow rate inside car body can be increased. Model 2 has the most air resistance and model 1 has the least among model 1, 2 and 3. Model 1 has the most air flow rate at inside. There are model 3 and 2 simulated according to flow rate. As the curved surface at radiator grill configuration increases in number, air flow rate becomes distributed uniformly. By considering the effect on air resistance and air flow rate at radiator grill, model 3 becomes the most effective configuration.

• Steel and Composite Structures
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• 제19권4호
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• pp.877-895
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• 2015

Connections to circular hollow steel sections (CHS) are considered one of the most complex and time consuming connections in steel construction. Such connections are usually composed of gusset plates welded to the outside of the steel tube or penetrating the steel tube. Design guides, accounting for the effect of connection configuration on the strength of the connection, are not present. This study aims to investigate, through experimental testing and a parametric study, the influence of connection configuration on the strength of one sided branch plate-to-CHS members. A notable effect was observed on the behavior of the connections due to its detailing changes with respect to capacity, failure mode, ductility, and stress distribution. A parametric study is performed using the calibrated analytical model to include a wider range of parameters. The study involves 26 numerical analyses of finite element models including parameters of the diameter-to-thickness (D/t) ratio, length of gusset plate, and connection configuration. Accordingly, a modification to the formulas provided by the current design recommendations was suggested to include connection configuration effects for the one sided branch plate-to-CHS members.

• International Journal of Aeronautical and Space Sciences
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• 제11권1호
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• pp.1-9
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• 2010

Numerical simulation of unsteady flows around helicopters was conducted to investigate the aerodynamic interaction of main rotor and other components such as fuselage and tail rotor. For this purpose, a three-dimensional inviscid flow solver has been developed based on unstructured meshes. An overset mesh technique was used to describe the relative motion between the main rotor, and other components. As the application of the present method, calculations were made for the rotor-fuselage aerodynamic interaction of the ROBIN (ROtor Body INteraction) configuration and for a complete UH-60 helicopter configuration consisted of main rotor, fuselage, and tail rotor. Comparison of the computational results was made with measured time-averaged and instantaneous fuselage surface pressure distributions for the ROBIN configuration and thrust distribution and available experimental data for the UH-60 configuration. It is demonstrated that the present method is efficient and robust for the simulation of complete rotorcraft configurations.

• 한국실내디자인학회논문집
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• 제16권6호
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• pp.197-204
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• 2007

In the spatial configuration of room-to-room art museums, openings and walls are important physical factors, and openings are a medium for connecting spaces. Also, by spatially composing walls and openings, spaces can be connected visually and physically, and movements and directions may vary depending on the location or size of walls and openings. In this study, 5 museums are investigated: Sainsbury Wing in London, Gemaldegalerie In Berlin, Alte Pinakotkek in Munich, Neue Pinakothek in Munich, and Staatsgalerie Stuttgart in Stuttgart. Using DepthMap program, the characteristics of visual-spatial composition of each museum are derived by comparing the Connectivity, Visual integration, and Isovist maximum radial. From an analysis of spatial distribution, a relationship with visibility is investigated. The results of this study showed that the combination of visual axial lines affect the spatial configuration of the room-to-room museums. Depending on the location of opening, the museums can be classified as follows: 1) Museums with the 1st visual axial line and the 2nd and 3rd auxiliary visual axial lines ; 2) museums with several equal visual axial lines; and 3) museums with only center axial line.

• 한국실내디자인학회논문집
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• 제21권5호
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• pp.343-354
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• 2012

Museums in Korea have experienced continuing quantitative growth since the late Choson Dynasty. However, a careful examination of visitors' viewing behavior has not been properly performed. Accordingly, social education for visitors in museums is not properly conducted despite the vast amount of information that museums possess. Given these circumstances, this study which focuses on the factors that influence visitors' behavior in museums intends to examine the effects that the configuration of exhibition space and the resulting visitor circulation patterns have on visitors' behavior with regard to visitor density. From this perspective, and considering five public historical museums within the seoul metropolitan area of korea, a correlation analysis has been conducted based upon quantitative analysis related to the configuration of exhibition space and visitors' observed viewing behaviors. The result of our study is that the configuration of exhibition space influences the patterns of visitor circulation, distribution of space, and the subsequent state of visitor density. Accordingly, the effects of visitor density on the viewing speed and other viewing behaviors could be identified. Based on these findings, the configurational differences in exhibition spaces were identified as one of the key factors that influence visitors' viewing behaviors.

• 전기학회논문지
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• 제56권8호
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• pp.1360-1366
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• 2007

In this paper, the load balancing which is one of the distribution power system's operation purposes was studied. Reconfiguration of Distribution power system presents that the configuration is changed by changing the switch on/off status which exists in the system according to the mentioned purpose. Through this method, the load of distribution power system is shown to be balanced. As a characteristic of complicated distribution power system, system is designed by being applied by OOP(Object Oriented Programming) method which connected more flexibly than existing Procedural Programming method, and the process of calculating the distflow and the loss of configurated system is shown. In addition, this paper suggests more efficient method compared by the results of reconfiguration on the purpose of the loss minimization and by the result of distribution power system reconfiguration on the purpose of load balancing. Moreover, it searches for the method to approach the global optimal solution more quickly.

• 한국산학기술학회논문지
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• 제21권5호
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• pp.623-629
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• 2020

본 연구는 항공기 기총발사 비행조건에서 Gun Port 주변 공기 유동장을 분석하여 디버터(Diverter) 옵션 형상에 따른 Gun Gas 유동량 및 경로를 확인하고 항공기 성능 및 안전성 영향을 확인하였다. Gun Port Diverter는 기총사격 시 발생하는 열을 효과적으로 낮춰주는 역할을 할 뿐아니라 Gun Gas를 상향방향으로 효율적으로 배출시키는 역할을 수행하며, 그 형상에 따라 Gun Gas 경로가 변경될 수 있다. 후방 Gun Port Diverter의 옵션 형상에 따라 기총 발사 시 Gun Gas의 유량, 경로, 압력을 분석하였다. Gun Port 내부 속도분포와 온도변화를 분석한 결과 후방 Diverter를 지나는 유량은 옵션 형상에 따라 급격이 감소하는 경향을 보이지만, 전방을 지나는 유량은 변화가 적은 비슷한 경향을 보임을 확인하였다. 따라서 기총발사 시 발생하는 Gun Gas는 후방 Gun Port Diverter 옵션 형상과 관계없이 항공기 표면에서 충분한 유동 거리가 확보되며, Diverter 옵션 형상에 따른 Gun Gas 유동의 정체는 Gun Port 내부 온도 상승에 큰 영향을 미침을 확인하였다.