• 동력기계공학회지
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• 제18권5호
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• pp.42-47
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• 2014

In this paper, the cycle performance analysis for the COP of supercritical heat pump using various refrigerants is presented to offer the basic design data for the operating parameters of the system. The working fluids are R134a, R22, R32, R290, R600, R600a, R1270 and R744. The operating parameters considered in this study include superheating degree of evaporator, temperature of gas cooler inlet and outlet, compressor efficiency and evaporating temperature in the supercritical heat pump system. The main results were summarized as follows : Superheating degree, temperature of gas cooler inlet and outlet, compressor efficiency and evaporating temperature of supercritical heat pump system have an effect on the COP of this system. With a thorough grasp of these effect, it is necessary to design the supercritical heat pump using R134a. And, in comparison of COP of supercritical heat pump using various refrigerants, R32 and R600 is the highest, and R744 is the lowest among other refrigerants. From these results, it is confirmed that the COP of supercritical heat pump using R744 is higher than that using freon refrigerants such as R32 and R134a.

• 한국주거학회논문집
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• 제15권5호
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• pp.21-32
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• 2004

The purpose of this study is to interpret Gaudi's philosophy of architecture through an analysis of the design characteristics in his remodeling of Casa Battlo. A review of the literature related to Casa Battlo as well as a field study in Barcelona to see the building were made for this study. The conclusions were as follows; Casa Battle is one of the best examples of Gaudi's attempts at creating a surreal atmosphere and should be evaluated in light of the following considerations: 1) Casa Battle as a remodeled house presented its own restrictions to Gaudi that he overcame by introducing characteristic design elements into the remodeling process; 2) the achievement, a perfect sculpture expressing continuity through a gorgeous colour scheme using different materials and design motifs with a dynamic spiral shape, originated from Gaudi's observations of nature and his experiences working in modeling studios; 3) a visualized embodiment of Gaudi's naturalism and functionalism through the impression of perpetual movement and continuity as formative symbols of genesis, life, death, and transmigration of the soul, originated from Gaudi's personal experiences of the early deaths of several close family members; 4) the design is meant to show the same processes of creation used by nature rather than a mere imitation of nature. Gaudi was not only a person dedicated obsessively to his profession as an architect, but also a rationalist fundamentally in the way he operated. It was expected that this study could be employed as a small stimulus to challenge the paradigm of housing remodeling projects -a hot issue in today's Korea- especially in their philosophical aspect.

• 벤처창업연구
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• 제6권3호
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• pp.43-59
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• 2011

최근 시장환경의 변화와 음악을 전공하는 음악학도가 많아지면서 음악학원이 위기를 맞고 있다. 무엇보다도 결정적인 이유는 음악경영의 경쟁자가 늘고 있고, 출산율 감소로 학원생이 줄어들어 학원 시장의 규모가 잠재적으로 축소되고 있다. 이에 따라 음악학원도 경영의 마인드가 필요하다. 본 연구는 음악학원의 운영의 성과인 경영성과에 영향을 미치는 요인을 규명하고자 한다. 본 연구의 내용은 3가지 영역으로 창업의 성공요인, 창업동기, 경영성과와 관련된 관련 내용을 살펴보고, 음악학원을 창업한 원장들을 대상으로 설문지를 통해서 경영성과에 영향을 미치는 요인을 분석하였다. 분석결과 경영성과에는 다양한 변수에 의해서 유의미한 영향을 미치는 것으로 나타났다. 따라서 음악학원도 벤처 경영의 접근방식이 필요하며, 음악학원, 거주환경, 상황적인 각각의 환경에 적합한 마케팅 전략이 필요하다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.231-231
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• 2010

GaN는 상온에서 3.4 eV의 넓은 밴드갭을 갖는 직접천이형 반도체로 우수한 전기적/광학적 특성 및 화학적 안정성으로 발광 다이오드 및 레이저 다이오드 등과 같은 광전소자 응용을 위한 소재로 많은 연구가 진행되어왔다. 특히, GaN 나노구조의 경우 낮은 결함밀도, 빠른 구동 및 고집적 특성 등을 가지기 때문에 효과적으로 소자의 광학적/전기적 특성을 향상시킬 수 있어 나노구조 성장을 위한 연구가 활발히 진행되고 있다. 최근에는 Metal organic vapor deposition (MOCVD), hot filament chemical vapor deposition (CVD), molecular beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE) 등 다양한 방법을 통해 성장된 GaN 나노구조가 보고되고 있다. 하지만 고가 장비 사용 및 높은 공정 온도, 복잡한 공정과정이 요구되며 크기조절, 조성비, 도핑 등과 같은 해결되어야 할 문제가 여전히 남아있다. 본 연구에서는 나노구조를 형성하기 위하여 보다 간단한 방법인 전기화학증착법을 이용하여 GaN 나노구조를 ITO 및 FTO가 증착된 전도성 glass 기판 위에 성장하였고 성장 메커니즘 및 그 특성을 분석하였다. GaN 나노구조는 gallium nitrate와 ammonium nitrate가 혼합된 전해질 용액에 Pt mesh 구조 및 전도성 glass 기판을 1cm의 거리를 유지하도록 담가두고 일정한 전압을 인가하여 성장시켰다. Pt mesh 구조 및 전도성 glass 기판은 각각 상대전극 (counter electrode) 및 작업전극 (working electrode)으로 사용되었고 전해질 용액의 농도, 인가전압, 성장시간 등의 다양한 조건을 통하여 GaN 나노구조를 성장하고 분석하였다. 성장된 GaN 나노구조 및 형태는 field emission scanning electron microscopy (FE-SEM)를 이용하여 분석하였고, energy dispersive X-ray (EDX) 분석을 통하여 정량 및 정성적 분석을 수행하였다. 그리고 성장된 GaN 나노구조의 결정성을 조사하기 위해 X-ray diffraction (XRD)을 측정 및 분석하였다. 또한, photoluminescence (PL) 분석으로부터 GaN 나노구조의 광학적 특성을 분석하였다.

• 한국식품조리과학회지
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• 제28권3호
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• pp.337-347
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• 2012

This study was performed through one-to-one interviews or group sessions with single un-married foreigners living and working in Korea. A total of 150 questionnaires were distributed, and 109 were analyzed. This demographic becomes immersed in local cuisine searching for new food dishes and experiences. These foreigners were an excellent test group who came from a non-Korean domestic cuisine background and who were subsequently exposed to Korean cuisine over an extended period during which changes occurred in their diets and food preferences. We found that the longer the foreigners stayed in Korea, the more they ate Korean food and adapted to traditional dishes such as Korean stews and hot-pots. In general, Chinese, Japanese, and South-east Asians regarded Korean food as nutritious, whereas people from a western or European background considered it health conscious food. In contrast, South-east Asians, in particular, found Korean food aroma unpleasant. This study describes how diets and views of Korean food evolved in foreigners with time by providing objective opinions and data on the acceptance of Korean food by foreigners and hints the direction in which Korean cuisine should be developed to further its globalization.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.162-167
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• 2003

조사재시험시설에 설치되어 있는 풀$(3m{\times}6m{\times}10m)$은 조사재운반용 수송용기(Cask)를 풀에 하역하여 풀물 속에서 조사재(시료)를 꺼내어 핫셀 내로 반입/반출하는 목적으로 사용한다. 수송용기를 풀에 하역하여 시료를 취출시 또는 버켓 엘리베이터에 장착시 모든 작업은 육안으로 행하여지기 때문에 항상 풀물을 양호한 수준으로 관리하여 수중취급 작업을 용이하게 하여야 하며, 방사성 오염관리 측면에서는 물에 잔존해 있는 방사성물질을 원자력법령에서 정하는 규정치 이하로 관리하여야 한다. 본 논문에서는 조사재시험시설에 설치하여 운용하고 있는 풀물정화장치 운전에 의한 방사능오염 및 수질에 대한 거동을 반출입된 시료별로 오염분포를 기술하였다.

• 한국태양에너지학회 논문집
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• 제32권4호
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• pp.9-16
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• 2012

Nanofluids using Carbon Nanotubes have a excellent thermal characteristic. In this study, for increasing the efficiency of solar collector, the thermal conductivity and viscosity of Ethanol-Oxidized Multi-walled Carbon Nanofluids were measured. Nanofluids were manufactured by ultra-sonic dispersing Oxidized Multi-walled Carbon Nanotubes(OMWCNTs) in ethanol at the rates of 0.0005 ~ 0.1 vol%. The thermal conductivity and viscosity of manufactured nanofluids were measured at the low temperature($10^{\circ}C$), the room temperature($25^{\circ}C$) and the high temperature($70^{\circ}C$). For measuring thermal conductivity and viscosity, we used transient hot-wire method and rotational digital viscometer, respectively. As a result, under given temperature conditions, thermal conductivity of the 0.1 vol% nanofluids improved 33.74% ($10^{\circ}C$), 33.14% ($25^{\circ}C$) and 32.36% ($70^{\circ}C$), and its viscosity increased by 37.93% ($10^{\circ}C$), 31.92% ($25^{\circ}C$) and 29.42% ($70^{\circ}C$) than the base fluids.

• 동굴
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• 제76호
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• pp.37-42
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• 2006

The Dielectric Barrier Discharge (DBD) is a nonequilibrium gas discharge that is generated in the space between two electrodes, which are separated by an insulating dielectric layer. The dielectric layer can be put on either of the two electrodes or be inserted in the space between two electrodes. If an AC or pulse high voltage is applied to the electrodes that is operated at applied frequency from 50Hz to several MHz and applied voltages from a few to a few tens of kilovolts rms, the breakdown can occur in working gas, resulting in large numbers of micro-discharges across the gap, the gas discharge is the so called DBD. Compared with most other means for nonequilibrium discharges, the main advantage of the DBD is that active species for chemical reaction can be produced at low temperature and atmospheric pressure without the vacuum set up, it also presents many unique physical and chemical process including light, heat, sound and electricity. This has led to a number of important applications such as ozone synthesizing, UV lamp house, CO2 lasers, et al. In recent years, due to its potential applications in plasma chemistry, semiconductor etching, pollution control, nanometer material and large area flat plasma display panels, DBD has received intensive attention from many researchers and is becoming a hot topic in the field of non-thermal plasma.

• 보존과학연구
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• 통권27호
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• pp.165-180
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• 2006

The research was conducted to understand type of iron used by those who lived at dwelling site of Yangsoo-ri in between the first century B.C. and the first century A.D. to make steel products and their technique such as steel making process and heat treatment, based on micro structure information obtained through microscopic metallographic structure analysis with SEM-EDS of six steel productsexhumed at the site. Key findings are summarized as below. In the sense that Si-Ca-Al style and less than 0.5% of Ti were found in the non-metallic inclusion, the material used for forged iron ware was magnetite resolved in that. It is, however, unclear whether magnetite was resolved at high temperature or at low temperature. Microscopic structure analysis revealed that forged steel products were made through repeated hot working, the technique of molding by hitting after heating in the process of resolving and molding iron. As a result, the iron used here for the products was not the iron ore which was produced through resolution from discarded cast iron axe, ingot iron. It is probable that to make those steel products, disposed-of cast iron was reused after being molded by decarburizing. Although a few of relics were analyzed for the research, they were of critical importance in defining the process of ironware production from the first century B.C. and the first century A.D. at the Yangsoo-ri region. Judging from the iron from A-19 dwellingsite, it is possible to conclude that the iron was manufactured from cast iron decarburized and yet more research has to be done into relics yetto be exhumed in order to ascertain the finding. All of these findings are believed to play a critical role in further studies to define the steel-manufacturing technique used on the central Korean peninsular in the ancient times.

• 한국표면공학회지
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• 제48권6호
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• pp.297-302
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• 2015

Nanocrystalline diamond(NCD) coated aluminium plates were prepared and applied as heat sinks for LED modules. NCD films were deposited on 1 mm thick Al plates for times of 2 - 10 h in a microwave plasma chemical vapor deposition reactor. Deposition parameters were the microwave power of 1.2 kW, the working pressure of 90 Torr, the $CH_4/Ar$ gas ratio of 2/200 sccm. In order to enhance diamond nucleation, DC bias voltage of -90 V was applied to the substrate during deposition without external heating. NCD film was identified by X-ray diffraction and Raman spectroscopy. The Al plates with about 300 nm thick NCD film were attached to LED modules and thermal analysis was carried out using Thermal Transient Tester (T3ster) in a still air box. Thermal resistance of the module with NCD/Al plate was 3.88 K/W while that with Al plate was 5.55 K/W. The smaller the thermal resistance, the better the heat emission. From structure function analysis, the differences between junction and ambient temperatures were $12.1^{\circ}C$ for NCD/Al plate and $15.5^{\circ}C$ for Al plate. The hot spot size of infrared images was larger on NCD/Al than Al plate for a given period of LED operation. In conclusion, NCD coated Al plate exhibited better thermal spreading performance than conventional Al heat sink.