• Carbon letters
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• 제11권1호
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• pp.38-40
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• 2010

Carbon supported electrocatalysts are commonly used as electrode materials for polymer electrolyte membrane fuel cells(PEMFCs). These kinds of electrocatalysts provide large surface area and sufficient electrical conductivity. The support of typical PEM fuel cell catalysts has been a traditional conductive type of carbon black. However, even though the carbon particles conduct electrons, there is still significant portion of Pt that is isolated from the external circuit and the PEM, resulting in a low Pt utilization. Herein, new types of carbon materials to effectively utilize the Pt catalyst are being evaluated. Carbon nanofiber/activated carbon fiber (CNF/ACF) composite with multifunctional surfaces were prepared through catalytic growth of CNFs on ACFs. Nickel nitrate was used as a precursor of the catalyst to synthesize carbon nanofibers(CNFs). CNFs were synthesized by pyrolysising $CH_4$ using catalysts dispersed in acetone and ACF(activated carbon fiber). The as-prepared samples were characterized with transmission electron microscopy(TEM), scanning electron microscopy(SEM). In TEM image, carbon nanofibers were synthesized on the ACF to form a three-dimensional network. Pt/CNF/ACF was employed as a catalyst for PEMFC. As the ratio of prepared catalyst to commercial catalyst was changed from 0 to 50%, the performance of the mixture of 30 wt% of Pt/CNF/ACF and 70wt% of Pt/C commercial catalyst showed better perfromance than that of 100% commercial catalyst. The unique structure of CNF can supply the significant site for the stabilization of Pt particles. CNF/ACF is expected to be promising support to improve the performance in PEMFC.

• Nuclear Engineering and Technology
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• 제42권5호
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• pp.474-499
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• 2010

This paper presents the mostortant developments implemented in the APOLLO2 spectral code since its last general presentation at the 1999 M&C conference in Madrid. APOLLO2 has been provided with new capabilities in the domain of cross section self-shielding, including mixture effects and transfer matrix self-shielding, new or improved flux solvers (CPM for RZ geometry, heterogeneous cells for short MOC and the linear-surface scheme for long MOC), improved acceleration techniques ($DP_1$), that are also applied to thermal and external iterations, and a number of sophisticated modules and tools to help user calculations. The method of characteristics, which took over the collision probability method as the main flux solver of the code, allows for whole core two-dimensional heterogeneous calculations. A flux reconstruction technique leads to fast albeit accurate solutions used for industrial applications. The APOLLO2 code has been integrated (APOLLO2-A) within the $ARCADIA^{(R)}$ reactor code system of AREVA as cross section generator for PWR and BWR fuel assemblies. APOLLO2 is also extensively used by Electricite de France within its reactor calculation chain. A number of numerical examples are presented to illustrate APOLLO2 accuracy by comparison to Monte Carlo reference calculations. Results of the validation program are compared to the measured values on power plants and critical experiments.

• 한국건축시공학회지
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• 제15권2호
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• pp.201-207
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• 2015

본 연구에서는 고로슬래그 다량치환 콘크리트의 탄산화 저항성 및 내동해성 향상을 위하여 팽창성 인공 기포인 Expancel과 ERCO를 조합 사용하고 그에 따른 일련의 실험을 진행하고자 한다. 연구결과에 따르면 ERCO 치환에 따라 비누화반응에 의한 모세관공극 충전효과로 탄산화 저항성이 향상되었으며, 이 때 문제점으로 지적된 내동해성 저하현상을 개선하기 위하여 Expancel을 사용하였는데, Expancel 치환율이 증가함에 따라 내동해성이 대폭 개선되는 것으로 나타났다. 이는 Expancel이 외부압력에 의해 선택적으로 체적축소현상과 기포간격계수의 감소에 기인한 결과로 판단된다.

• 설비공학논문집
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• 제17권10호
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• pp.883-890
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• 2005

In this study, 2 pure hydrocarbon refrigerants of R1270 (Propylene) and R290 (Propane) and 3 binary mixtures composed of R1270, R29O and R152a were tested in a refrigerating bench tester with a scroll compressor in an attempt to substitute R502 used in most of the low temperature applications. The test bench provided 3\sim3.5$ kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. All tests were conducted under the same external conditions resulting in the average saturation temperatures of -28 and $45^{\circ}C$ in the evaporator and condenser, respectively. Test results showed that all refrigerants tested had $9.6\sim18.7\%$ higher capacity and $17.1\sim27.3\%$ higher COP than R502. The compressor discharge temperature of R1270 was similar to that of R502 while those of all other refrigerants were $23.7\sim27.9\%$ lower than that of R502. For all alternative refrigerants, the amount of charge was reduced up to $60\%$ as compared to R502. Overall, these alternative refrigerants offer better system performance and reliability than R502 and can be used as long term substitutes for R502 due to their excellent environmental properties.

• 암석학회지
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• 제16권2호
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• pp.73-81
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• 2007

경상북도 포항시 장기지역의 제3기 장기분지에는 제 3기 장기층군의 상부현무암질응회암이 넓게 분포하고 있으며, 그 가운데에 연일현무암이 단속적으로 산출되고 있다. 본 연구의 목적은 이들 현무암질암의 산상과 암상의 조사를 통하여 그 형성과정을 밝히는데 있다. 야외조사 결과 본역의 현무암질암은 다음과 같이 크게 4가지 특징적인 암상으로 구분된다: (1) sideromelane shard hyaloclastite, (2) pillow breccia, (3) entablature-jointed basalt, 그리고 (4) in situ breccia. 본역에서 관찰되는 현무암질암의 여러 특징에 의하면 장기지역의 장기분지에 분포하는 상부현무암질응회암은 hyaloclastite에 해당하며. 현무암질 용암의 수저분출 후 일어난 비폭발성 급랭 파쇄작용에 의해서 형성된 것으로 추론된다.

• 한국의류학회지
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• 제31권1호
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• pp.21-32
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• 2007

The purpose of this study is to establish the idea of sustainable slow design by analyzing literatures and preceding cases, based on the external elements of a design including forms, the methods of expression, materials and colors. This study reviewed the previous literature of books and pictures related to the research for case studies and content analysis. fashion books, magazines, and web-sites published from 2000 to 2005 were analyzed for this research. The sustainable slow design trends in fashion can be summarized as follow. The first is a timeless style which has sustain ability in design independently of the versatile fads and relies on functionality, serving the purpose of design. One of the examples is both clothes designed by Burberry and suits by Chanel. The second is a hand-touch style which the more time for outputs can be positively tolerated, in favor on eco-friendly design through the techniques of manual arts. The third is a renewable design which the combined values of design with reuse and renewal result in recreation of past ecology as shown in the technique of designs by mix & match. The forth is a transformable design which features the multi-purpose and multi-forms, eventually extending the lift cycle of products. As a result of analysis of the four designs above, it can be inferred that the representation of past styles, the mixture of old design with new design, the appropriate combination of conventional fabrics with advanced ones, the ecological trends of sports look was emerging.

• 설비공학논문집
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• 제18권10호
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• pp.761-767
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• 2006

In this study, performance of 2 pure hydrocarbons R290 and R1270 was measured in an attempt to substitute R22 under 3 different temperature conditions. They were tested in a refrigerating bench tester with a hermetic rotary compressor. The test bench provided about 3.5 kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. All tests were conducted under the same external conditions resulting in the average saturation temperatures of $7/45^{\circ}C$ and $-7/41^{\circ}C$ and $-21/28^{\circ}C$ in the evaporator and condenser, respectively. Test results show that the coefficient of performance (COP) of these refrigerants is up to 11.54% higher than that of R22 in all temperature conditions. Compressor discharge temperatures were reduced by $14{\sim}31^{\circ}C$ with these fluids. There was no problem with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of charge was reduced up to 58% as compared to R22. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for residential air-conditioning and heat pumping application.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.58-63
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• 2006

In this study, performance of 2 pure hydrocarbons and 3 mixtures was measured in an attempt to substitute R22 under 3 different temperature conditions. The mixtures were composed of R1270(propylene), R290(propane) and R152a. They were tested in a refrigerating bench tester with a hermetic rotary compressor The test bench provided about 3.5 kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. All tests were conducted under the same external conditions resulting in the average saturation temperatures of $7^{\circ}C/45^{\circ}C$ and $-7^{\circ}C/41^{\circ}C$ and $-21^{\circ}C/28^{\circ}C$ in the evaporator and condenser, respectively. Test results show that the coefficient of performance (COP) of these refrigerants is up to 11.54% higher than that of R22 in all temperature conditions. Compressor discharge temperatures were reduced by $14{\sim}31^{\circ}C$ with these fluids. There was no problem with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of charge was reduced up to 58% as compared to R22. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for residential air-conditioning and heat pumping application.

• 유기물자원화
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• 제27권2호
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• pp.51-56
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• 2019

황화수소는 매립가스와 바이오가스 사용 전에 제거해야 하는 유해한 불순물이다. 본 연구에서는 공기 산화를 활용한 황화수소 저감 방법을 연구하였다. C시 매립장에서 발생하는 매립가스의 유량 조절이 가능한 실규모 황화수소 저감 장치를 운전하였다. 실험 결과, 세정액 내 용존 철 농도는 황화물 산화 효율에 유의한 영향을 미쳤다. 매립지 발생 침출수 내 철 성분은 매립가스 내 황화수소 제거를 위한 용도로 철킬레이트와 혼용할 수 있었다. 철 농도가 90 mM 이상인 경우 9 초 이내의 접촉 시간에서 83 % 이상의 $H_2S$가 제거되었다. 따라서 촉매 산화 흡착법은 매립가스 및 바이오가스 정제를 위한 용도로서 충분히 가치가 있는 것으로 판단되었다.

• 공업화학
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• 제30권4호
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• pp.415-420
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• 2019

비이온 계면활성제와 유화안정제가 O/W 유화 제형에 미치는 영향을 살펴보기 위하여 비이온 계면활성제와 유화안정제 종류를 달리한 여러 제형을 만들어 이들의 유변학적 특성을 비교하였다. 친수성 비이온 계면활성제는 polysorbate 60 (Tween 60), PEG-60 hydrogenated castor oil (HCO 60), octyldodeceth-16 (OD 16), ceteareth-6 olivate (Olivem 800) 등을 사용하였고, 유화안정제로는 cetyl alcohol, glyceryl monostearate, stearic acid 등을 각각 사용하였다. Octyldodeceth-16을 사용한 유화 제형에서만 상분리가 일어나고 나머지 제형은 모두 안정한 상을 유지하였다. 계면활성제 ceteareth-6 olivate와 유화안정제 cetyl alcohol을 혼합 사용한 제형의 점도, 경도, 크림성 등이 가장 높게 나타나고 유화된 입자 사이즈도 가장 큰 값으로 측정되었다. 이와 같은 결과는 유화 제형에 액정이 많이 생성되면서 네트워크 구조의 텍스처가 형성되었기 때문이다. 이 제형에서는 탄성적 특성이 크게 나타나고 힘이 가해지는 이력에 따라 점도 값이 달라지는 씩소트로픽 현상이 나타났다.