• 대한건축학회논문집:계획계
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• 제34권8호
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• pp.13-22
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• 2018

The purpose of this study was to consider the energy generation of the building as well as the energy demand of the building in terms of zero energy building design. The reason why the zero energy building viewpoint should be discussed is that direction of the building, heat transfer rate of the building, and the S/V ratio of the building are variables related to energy demand and solar panels installed on the building roof and building envelope are variables related to energy generation. This study proceeded as follows; Firstly, the simulation model of large office and elementary school has the same mutual volume and total floor area, and the each floor area and number of floors are adjusted so that the S/V ratio is different. To the next, the energy demand and energy generation of the simulation model were derived based on the meteorological data of Seoul, Daejeon, Busan. Finally, energy demand, energy generation, and final energy demand were compared with heat transfer rate, S/V ratio, building type, region, and orientation. The results of this study is that consideration of solar power generation in terms of energy generation should be taken into consideration at the same time in consideration of the heat transfer rate, the shape, the region and the direction of the zero energy building design.

• International Journal of Aeronautical and Space Sciences
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• 제13권2호
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• pp.170-187
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• 2012

Recent years have seen an outpour of revived interest in the use of airships for a number of applications.Present day developments in materials, propulsion, solar panels, and energy storage systems and the need for a more eco-oriented approach to flight are increasing the curiosity in airships, as the series of new projects deployed in recent years show; moreover, the exploitation of the always mounting simulation capabilities in CAD/CAE, CFD and FEA provided by modern computers allow an accurate design useful to optimize and reduce the development time of these vehicles.The purpose of this contribution is to examine the different aspects of airship development with a review of current modeling techniques for airship dynamics and aerodynamics along withconceptual design and optimization techniques, structural design and manufacturingtechnologies and, energy system technologies. A brief history of airships is presented followed by an analysis of conventional and unconventional airships including current projects and conceptual designs.

• 전기학회논문지
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• 제59권6호
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• pp.1046-1052
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• 2010

In residential house, photovoltaic (PV) system among various alternatives in renewable energy system is the most efficient and feasible solution for reducing energy consumption and electricity cost. However, relatively high initial cost make people reluctant to install PV system in their houses. Therefore, in the initial state for PV system installation in the house, it is very important to decide proper capacity of the PV system considering the expected energy usage and solar energy supplying condition with the house. This paper proposes a novel optimization model for deciding appropriate capacity of the PV system for residential house. The objective function of the model is to minimize the annual cost including electricity bill, operation and maintenance cost, and annual fixed cost calculated from the initial installation cost based on capital recovery factor (CRF). The model also shows the optimal inclining angle of PV panels of the system. In this paper, we estimate the PV output using PVWATTS (PV simulator of Office of Energy Efficiency and Renewable Energy) and find optimal solutions by Sequential Quadratic Programming (SQP) method using MATLAB software. The proposed approach is finally applied to a residential model house in Gangneung, Gangwon-Do and verified its feasibility for adopting to PV system design for residential houses.

• 한국항공우주학회지
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• 제36권11호
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• pp.1126-1131
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• 2008

본 논문은 궤도 기하학 기반 바이어스 추정기법을 다목적실용위성 1호 및 2호의 자기센서 측정데이터에 적용하여 위성체 태양전지판과 전장박스에서 발생하는 유도자기장 바이어스를 추정한다. 유도자기장 바이어스의 추정과 적절한 보정은 자기센서의 노후화를 대처하고 수명을 최대한 연장하여 정상적으로 위성 임무를 수행을 가능하게 한다.

• 전기학회논문지
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• 제64권2호
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• pp.222-227
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• 2015

This paper presents the optimal energy generation systems for economical EVs(Electric Vehicles) charging stations located in an island area. The system includes grid electricity, diesel generator and renewable energy sources of wind turbines and PV(Photovoltaic) panels. The independent generation system is designed with data resources such as annual average wind speed, solar radiation and the grid electricity price by calculating system cost under different structures. This sensitive analysis on the varying data resources allows for the configuration of the most economical generation system for charging stations by comparing initial capital, operating cost, NPC(Net Present Cost) and COE(Cost of Energy). Depending on the increase of the grid cost, the NPC variation of the most economical system which includes renewable energy generations and grid electricity can be smaller than those of other generation systems.

• Architectural research
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• 제20권3호
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• pp.93-102
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• 2018

With the change in Earth's ecosystems due to climate change, a number of studies on zero energy buildings have been conducted globally, due to the depletion of energy and resources. However, most studies have concentrated on residential and office buildings and the performance predictions were made only in the design phase. This study verifies the zero-energy performance in the operational phase by acquiring and analyzing data after the completion of an exhibition building. This building was a retention building, in which a renewable energy system using a passive house building envelope, solar photovoltaic power generation panels, as well as fuel cells were adopted to minimize the maintenance cost for future energy-zero operations. In addition, the energy performance of the building was predicted through prior simulations, and this was compared with actual measured values to evaluate the energy performance of the actual operational records quantitatively. The energy independence rate during the measurement period of the target building was 123% and the carbon reduction due to the energy production on the site was 408.07 tons. The carbon reduction exceeded the carbon emission (331.5 tons), which verified the carbon zero and zero-energy performances.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.579-579
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• 2012

Graphene has recently been a subject of much interest as a potential platform for future nanodevices such as flexible thin-film transistors, touch panels, and solar cells. And chemical vapor deposition (CVD) and related surface segregation techniques are a potentially scalable approach to synthesizing graphite films on a variety of metal substrates. The structural properties of such films have been studied by a number of methods, including Raman scattering, x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). An understanding of the structural quality and thickness of the graphite films is of paramount importance both in improving growth procedures and understanding the resulting films' electronic properties. In this study, we synthesized the few-layered grapheneunder optimized condition to figure out the growth mechanism seen in CVD-grown graphenee by using various electron microscope. Especially, we observed directly film thickness, quality, nucleation site, and uniformity of grpahene by using AEM. The details will be discussed in my presentation.

• 한국표면공학회지
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• 제40권3호
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• pp.144-148
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• 2007

To prepare the transparent electrode for electronic devices such as flat panel or flexible displays, solar cells, and touch panels; tin doped $In_2O_3$ (ITO) films with low resistivity and a high transparency were fabricated using a facing target sputtering (FTS) system at the various oxygen gas flow rate. The carrier concentration and mobility of ITO films were measured by Hall Effect measurement. And the transmittance was measured using the UV-VIS spectrometer. As a result, we can obtain the ITO thin films prepared at 10% oxygen gas flow ratio, thickness 150 nm with transmittance 85% and resistivity $8.1{\times}10^{-4}{\Omega}cm$ and surface roughness 5.01 nm.

• 한국추진공학회지
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• 제10권3호
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• pp.99-108
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• 2006

본 논문은 기존 파이로 부품인 폭발볼트의 기능을 그대로 유지하면서 분리시 발생되는 파편 및 충격파의 악 작용과 파편을 완벽히 제거할 수 있게 형상기억합금(Shape Memory Alloy)을 이용한 분리장치(Fangibolt) 모델의 설계 및 모사에 관한 연구이다. Frangibolt는 기존 폭발볼트에서 사용하는 분리화약을 사용하지 않고 스마트 소재인 형상기억합금의 온도에 따라 변화되는 미세조직에 따른 응력생성을 이용하여 파이로 장치를 분리시키는 Non Pyrotechnic 장치로써, 실제 Frangibolt노치부에 생성되는 응력의 분포 및 분리거동을 해석함으로써 Frangibolt 설계에 필요한 인자를 파악할 수 있었다. 또한 볼트 설계방법의 최적화를 제시함으로써 향후 다른 종류의 SMA을 이용한분리장치 설계 및 해석 모델에 기초자료를 제공할 수 있을 것이다.

• Transactions on Electrical and Electronic Materials
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• 제18권4호
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• pp.190-194
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• 2017

Present-day solar panels incorporate inverters as their core components. Switching devices driven by specialized power controllers are operated in a transformerless inverter topology. However, some challenges associated with this configuration include the absence of isolation, causing leakage currents to flow through various components toward ground. This inevitably causes power losses, often being also the primary reason for the power inverters' analog equipment failure. In this paper, various aspects of the leakage currents are studied using different circuit analysis methods. The primary objective is to convert the leakage current energy into a usable DC voltage source. The research is focused on harvesting the leakage currents for producing circa 1.1 V, derived from recently developed rectifier circuits, and driving a $200{\Omega}$ load with a power in the milliwatt range. Even though the output voltage level is low, the harvested power could be used for charging small batteries or capacitors, even driving light loads.