• 한국세라믹학회지
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• 제42권12호
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• pp.777-786
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• 2005

The Solid Oxide Fuel Cell (SOFC) is an electrochemical device to convert chemical energy of a fuel into electricity at temperatures from about 600 to $1000^{\circ}C$. The SOFC offers certain advantages over lower temperature fuel cells, notably its ability to use CO as a fuel rather than being poisoned by it, and high grade exhaust heat for combined heat and power, or combined cycle gas turbine applications. This paper reviews the operating principle, materials for different cell and stack components, cell designs, and applications of SOFCs. Among all designs of Solid Oxide Fuel Cells (SOFCs), the most progress has been achieved with the tubular design. However, the electrical resistance of tubular SOFCs is high, and specific power output $(W/cm^2)$ and volumetric power density $(W/cm^3)$ low. Planar SOFCs, in contrast, are capable of achieving very high power densities.

• 한국수소및신에너지학회논문집
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• 제32권6호
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• pp.649-655
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• 2021

The recently proposed Kalina based power and cooling cogeneration cycles (KPCCCs) have shown improvement in the energy utilization of the system compared to the basic Kalina cycle. This paper suggests a combined tri-cogeneration system for power, heating and cooling based on the Kalina cycle. And thermodynamic performances of the suggested system based on the first and second thermodynamic laws are parametrically investigated with respect to the ammonia mass fraction and the boiler pressure. Results showed that the thermodynamic performance of the system could be greatly improved compared to the former KPCCCs.

• 한국건설순환자원학회논문집
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• 제7권4호
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• pp.287-294
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• 2019

고로슬래그 미분말은 뛰어난 염해 저항성 및 내화학성을 가지고 있어 콘크리트에 널리 쓰여왔으나, 고분말도에 따라 수화열과 건조 수축에 의한 균열이 보고되고 있다. 국제 표준에서는 콘크리트에 저분말도 고로슬래그 미분말의 폭 넓은 상용화 및 균열 저감을 위하여 3,000급 저분말도 고로슬래그 미분말이 포함되어 있다. 본 연구에서는 저분말도 고로슬래그 미분말을 치환한 콘크리트(50%의 물-결합재비와 3,000급 고로슬래그 미분말을 60% 치환)와 삼성분계 콘크리트(50% 물-결합재비와 4,000급 고로슬래그 미분말 및 플라이애시를 총 60% 치환)가 고려되었다. 저분말도 고로슬래그 미분말을 치환한 콘크리트와 삼성분계 콘크리트의 강도 차이는 재령 3일차에서 재령 91일차까지 확연한 차이는 없었으며 우수한 염해와 탄산화 저항성을 나타내었다. 또한 적절한 공기량을 함유하여 두 배합 모두 90.0 이상의 높은 내구성 지수를 나타내었다. 배합개선을 통하여 저분말도 GGBFS 콘크리트의 초기강도 개선한다면 낮은 수화열 및 고내구성을 가진 매스 콘크리트를 제조할 수 있으리라 판단된다.

• 대한건축학회논문집:계획계
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• 제35권11호
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• pp.25-34
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• 2019

It is important to design windows in a reasonable way considering the performance characteristics of the elements of the window rather than just to increase the thermal energy performance of the window. In this study, the Heat-transfer Coefficient as insulation performance of the windows and together with the grade of the glass's SHGC (Solar Heat Gain Coefficient) were analyzed to relate to the energy efficiency performance of the building by azimuth angle. Based on this basic study, the Heat-transfer Coefficient of windows and the SHGC rating of glass were applied to the unit plan of apartment building, and the Heating and Cooling Demand were analyzed by azimuth angle. Apartment plan types were divided into 2 types of Non-extension and extension of balcony. The designPH analysis data derived from the variant of the Heat-transfer Coefficient and SHGC, were put into PHPP(Passive House Planning Package) to analyze precisely the energy efficiency(Heating and Cooling Demands) of the building by azimuth angle. In addition, assuming the 'ㅁ' shape layout, energy efficiency performance and potential of PV Panel installation also were analyzed by floors and azimuth angle, reflecting the shading effects by surrounding buildings. As the results of the study, the effect of Heat Gain by SHGC was greater than Heat Loss due to the Heat-transfer Coefficient. So it is more effective to increase SHGC to satisfy the same Heating Demand, and increasing SHGC made possible to design windows with low Heat-transfer Coefficient. It was also revealed that the difference in annual Heating and Cooling Demands between the low, mid and high floor households is significantly high. In addition to it, the installation of PV Panel in the form of a shading canopy over the window reduces the Cooling Load while at the same time producing electricity, and also confirmed that absolute thermal energy efficiency could not be maximized without controlling the thermal bridge and ventilation problems as important heat loss factors.

• 한국구조물진단유지관리공학회 논문집
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• 제23권4호
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• pp.96-102
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• 2019

고분말도 슬래그를 사용할 경우 초기재령에서의 강도발현은 우수하나 수화열 및 품질관리에 따른 문제가 발생하기 쉽다. 본 연구에서는 3000급 저분말도의 고로슬래그 미분말을 혼입한 콘크리트의 강도특성 및 내구특성을 분석하였다. 작업성을 기준으로 3가지 배합을 고려하였으며, 압축강도와 내구특성시험이 수행되었다. 강도특성 결과 3000급 슬래그를 혼입한 콘크리트는 28일 재령에서 OPC(Ordinary Portland Cement) 배합 대비 강도가 떨어지지만 장기재령에서는 잠재수경성의 촉진으로 인하여 큰 차이가 나타나지 않았다. 탄산화 및 동결융해 실험에서는 4200급 슬래그 배합 대비 약간 우수한 저항성능이 나타났는데, 이는 동일 슬럼프를 목표로 배합을 진행하여 3000급 슬래그 배합에 단위수량을 적게 고려하였기 때문이다. 장기재령의 경우, 3000급 슬래그 배합의 염화물확산계수는 OPC 배합 대비20% 수준으로 감소하여 우수한 내염해특성이 평가되었다. 단위수량을 조정하고 3000급 저분말도의 고로슬래그 미분말을 혼입하여 사용할 경우, 기존 분말도의 슬래그가 사용된 콘크리트 및 OPC 콘크리트와 비교시 우수한 작업성능과 내구특성을 확보할 수 있을 것으로 판단된다.

• 감성과학
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• 제14권1호
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• pp.117-126
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• 2011

이 연구는 감성의류용 형상기억 메모리직물의 제조 방법과 물성을 조사하기 위해 저온열처리와 정장열처리 가연법을 폴리프로필렌 POY와 SDY에 각각 적용하고 이들 사를 사용하여 PP형상기억메모리 직물을 air-jet직기에서 제조하였다. 물성비교를 위해서 PET와 PTT형상기억메모리 직물도 같이 제직하여 4가지 형상기억 메모리 직물시료를 만들고 이들의 여러 가지 물성을 측정 비료분석하여 다음과 같은 결론을 얻었다. PP형상기억 메모리 직물에 사용하기 위해 저온가연법과 정장열처리법에 의해 만든 PP가연사의 물성은 절단강 신도가제직성에 문제가 없는 값을 가졌으며 특히 열수축율이 습열은 1.5% 이하 건열은 3~5% 범위를 가짐으로써 PTT의 5~8%의 높은 열수축율에 비해 열적 안정성을 가졌다. PP형상기억 메모리 소재의 변형된 형태를 유지하는 소성적 성능 특성 평가법인 Toray 방추성 평가는 PP소재가 PTT와 같은 5급을 나타냄으로써 우수한 변형 유지특성을 보였다. 또한 PP형상기억 메모리소재의 보온성은 PTT소재보다 약 56% 향상된 결과를 보였으며 스프레이법에 의한 발수성은 PTT소재에 발수처리한 소재와 동일하게 5급의 우수한 발수성을 보였다. 그리고 PP형상기억 메모리소재의 형상기억 특성을 평가 할 목적으로 3D 이미지 방법과 카메라 측정결과 PTT소재와 비슷한 형상기억 특성을 보임을 확인 할 수 있었다.

• Journal of Welding and Joining
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• 제17권4호
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• pp.46-52
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• 1999

Some of the pressurized reactor pressure vessels used in many chemical plants are made of low alloy carbon steel plates internally clad with an austenitic stainless steel for improved anti-corrosion properties. In this study, metallurgic structure of the weld interface of A 387 Grade12Class1 low alloy carbon steel claded with A182-F321 austenitic stainless steel after thermal exposure simulation heat treatment was investigated to display a characteristic behavior of dissimilar metal weld interface with thermal exposure during service at high temperature and pressure. EPMA, STEM, vickers-hardness test were performed and the results were correlated with the microstructure. To estimate the depth of the carburized/decarburized bands quantitatively, a model for carbon diffusion was proposed. The validity of the proposed theoretical relationships was confirmed by the directly measured data from the welded parts failed during service.

• 한국태양에너지학회 논문집
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• 제37권2호
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• pp.59-66
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• 2017

This paper compares the output power of different types of small Stirling engines in conjunction with the utilization of low grade thermal energy. A series of experimental measurements were performed to assess the output power of each engine under different conditions of the temperature difference between the hot and cold ends as well as applied weight. Results are presented in terms of torque and output power per heat transfer area. Among tested, the MM-7 engine produced the highest power of 4.455mW ($321mW/m^2$) under a temperature difference of $40^{\circ}C$.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.281-285
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• 2008

Effective use of available energy sources is of general concern along with the issues of global warming and unstable oil price. As one of the effort to recover waste heat from industrial facilities effectively, researchers have interest in a technology called organic Rankine cycle(ORC), in which the working fluid is some organic liquid instead of water. Known to have poor efficiency already, this old technology is considered to give an innovative solution to utilizing low grade energy sources, by improving the efficiency. Nano fluidics, coatings and the use of additives are the examples of these efforts. In the present study, we present simulated performance of a horizontal tube type condenser geometry. N-hexanr and isopentane are compared to water vapor case under 1 atm and the inet cooling water temperature of $20^{\circ}C$. EES(Engineering Equations Solver) is used for the present work.

• 한국표면공학회지
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• 제27권4호
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• pp.193-206
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• 1994

A wear behavior of electroless (Ni-P-X, X: SiC, $Al_2O_3$, Diamond) composite coating layers, formed under various conditions on commerical grade low carbon steel, has been investigated using Taber abrasion tester and scanning electron microscope. Several factors, which are type of particles, co-deposited content, particle size, distribution of particles and heat-treatment, influenced the wear resistance. The wear resistance of the composited coating layers after heat-treatment at $400^{\circ}C$ for 1 hr was increased 70 times with diamond, 15 times with SiC and 8 times with $Al_2O_3$, compared with the electroless nickel plating layer without heat-treatment.