• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.73.1-73.1
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• 2011

석탄가스화 복합발전(IGCC) 시스템은 고온 고압으로 운전되는 가스화기에서 미분탄을 산소와 함께 가스화하여 주로 CO 및 $H_2$를 생성하고 이때 발생되는 먼지 및 황성분은 각각 집진기 및 탈황장치에서 제거되며, 석탄 회분은 고온에서 용융되어 슬래그의 형태로 배출되는 방식을 사용하고 있다. 본 연구에서는 석탄가스화 복합발전시스템 설계에 필요한 기본자료를 파악하기 위해서, 고온 고압의 운전조건에서 1일 3톤의 석탄을 처리할 수 있는 Bench Scale급 석탄가스화기를 이용하여 가스화에 사용된 원탄 및 가스화기 설비의 각 지점에서 샘플링한 고체 시료를 중심으로 열화학적 특성을 살펴보았다. 가스화 실험은 아역청탄 계열의 ABK 석탄을 대상으로 가스화기 내부의 온도와 압력을 $1400{\sim}1450^{\circ}C$, $7.5{\sim}7.6Kg/cm^2$로 유지시키면서 실시하였다. 실험에 사용된 석탄 시료의 기본적인 물성치를 조사하기 위하여 표준방법에 따라 석탄의 공업분석, 원소분석, 발열량분석 등을 실시하였다. 석탄가스화기에서 배출된 슬래그와 대상 석탄 회분의 특성을 파악하기 위해서 XRF를 이용한 회분의 성분분석, Heating Microscope를 이용한 회분의 용융점 분석, XRD를 이용한 회분과 슬래그내의 화합물의 형태 및 결정구조 파악, SEM을 이용한 슬래그의 형상 등을 분석하였다. 또한 석탄가스화기 시스템을 구성하는 각 설비의 특성을 파악하기 위해서 관련 설비의 특정 지점에서 채취한 시료의 입도분석, 원소분석, 촤 회분 무게비, 슬래그중의 잔존탄소함량, 슬래그와 슬래그로부터 제조된 용출수내의 중금속 함량분석 등을 실시하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.2
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• pp.182-188
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• 2011

In this paper, analysis on the performance characteristics of R744-R404A cascade refrigeration system is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree, compressor efficiency, and condensing and evaporating temperature in R404A high- and R744 low-temperature cycle, respectively. The main results were summarized as follows : It was observed that the highest COP of the system is achieved by higher superheating degree in R744 cycle than that in R404A cycle. The COP of the system increased by giving the subcooling degree in both cycles. The COP of the cascade system is the highest value when the system is operated at an optimum evaporation temperature.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.11
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• pp.1091-1097
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• 2017

Sales of commercial-type cooling fans intended for application in military electronics are often discontinued during equipment production. This results in requirements for alternative fan selection as well as equipment performance and reliability tests, such as high-temperature operation testing. This study deals with alternative fan selection and verification methods that can be used during the production process. First, an alternative fan was selected by calculating the flow and pressure required to effectively cool the equipment, then the feasibility of the selected fan was verified using a reliable CFD heat dissipation analysis model. Following this, a high-temperature operation test was performed using the alternative fan in the equipment. Results demonstrated that the equipment satisfied its required function in a high-temperature environment, and the main parts as well as internal air temperature were found to be thermally stable.

• Fire Science and Engineering
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• v.28 no.1
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• pp.20-25
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• 2014

Steel column is very important an structural element in steel framed building and plays a key role in sustataining the applied external load. Generally, the fire resistance performance of steel column has been executed by application of fire standard and vertical furnace having a limitation in height. Therefore, the fire resistance test was conducted with a H-section column having 3500 mm in length and hinge to hinge boundary condition. And the fire protective material derived from the fire test can be applied to any kind of boundary conditions and lengths. However, it is hard to determine the fire resistance. In this paper, to make sure the structural stability of them at high temperature according to various boundary conditions and lengths of H-section column, an analysis was done by using the mechanical properties and an heat transfer theory.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.2
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• pp.94-98
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• 2007

The fault current limiting characteristics of a flux-lock type superconducting fault current limiter (SFCL) considering hysteresis characteristics of a flux-lock reactor, which is an essential component of the flux-lock type SFCL, were investigated. In the normal state, the hysteresis loss of iron core in the flux-lock type SFCL does not happen due to its winding's structure. From the equivalent circuit for the flux-lock type SFCL and the fault current limiting experiments, the hysteresis curves could be drawn. Through the hysteresis curves together with the fault current level due to the inductance ratio between the primary and the secondary windings, the increase of the number of turns in the secondary winding of the flux-lock type SFCL made the fault current level increase. On the other hand, the saturation of iron core was prevented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.1-8
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• 2018

The object of this paper is to find the characteristics of fire proof materials through an analytical method and to suggest a proper approach for fire-proof design of reinforced concrete beam strengthened with fiber reinforced polymer (FRP). Heating tests for fire-proof materials were conducted and the thermal conductivities and specific heats of them were simulated through finite element analyses. In addition, a finite element analysis on the beam specimen strengthened with FRP under high temperature, which was conducted by previous researchers, was performed and the analytical result was compared with test result. And then the compatibility of the analytical approach was evaluated. Finally, the heat resistance characteristic of RC beam strengthened with FRP was analyzed by the proposed analytical method and the strength decrease of the beam due to the high temperature was evaluated. From the comparison with analytical and test result, it was found that the heat transfer from outside to inside through the fire-proof materials can be suitably simulated by using the proposed analytical approach.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.5
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• pp.528-532
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• 2007

The generation of high-purity hydrogen from hydrocarbon fuels is essential for efficient operation of fuel cell. In general, most feasible strategies to generate hydrogen from hydrocarbon fuels consist of a reforming step to generate a mixture of $H_2$, CO, $CO_2$ and $H_2O$(steam) followed by water gas shift(WGS) and CO clean-up steps. The WGS reaction that shifts CO to $CO_2$ and simultaneously produces another mole of $H_2$ was carried out in a two-stage catalytic conversion process involving a high temperature shift(HTS) and a low temperature shift(LTS). In the WGS operation, gas emerges from the reformer is taken through a high temperature shift catalyst to reduce the CO concentration to about $3\sim4%$ followed to about 0.5% via a low temperature shift catalyst. The WGS reactor was designed and tested in this study to produce hydrogen-rich gas with CO to less than 0.5%.

• Fire Science and Engineering
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• v.24 no.1
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• pp.116-121
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• 2010

The present study has been performed to investigate the ignition characteristics of a n-dodecane fuel droplet on the hot surface. Simplified bench scale test setup was built to examine the effect of air flow on the ignition temperature of fuel droplet. IR pyrometric sensor was used to measure the surface temperature, the measured temperature using IR pyrometer was directly compared with k-type thermocouple. The ignition of n-dodecane fuel droplet was divided into two stage - cool flame and hot flame - with the air flow rate except the case of air flow rate 3.0 lpm. The ignition temperature and probability was greatly affected by the air flow rate and the MHSIT of the present study was about $300^{\circ}C$ for air flow rate of 0.5 lpm.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.2
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• pp.93-101
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• 2019

The mechanical properties and microstructure of 1st stage used and casted buckets of $1,100^{\circ}C$ class gas turbine were analyzed to evaluate quality of the components. Gas turbine 1st stage buckets are exposed and operated in the most severe environment except 1st nozzle among the hot path gas components. Additionally, since the 1st stage bucket is a rotating component, so it may cause additional damage to the rear buckets and nozzles which cause a huge financial loss. Therefore, the quality of the casted bucket must be evaluated prior to use at the plant site. In this study, the microstructure analysis and mechanical properties of the casted bucket were evaluated to verify the casting quality and it was confirmed that the quality conditions designed by KEPCO were satisfied. A bucket operated 46% (11,067EOH) of its life time also evaluated for quality comparison.

• Composites Research
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• v.22 no.3
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• pp.60-65
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• 2009

The mechanical behavior of carbon fiber reinforced polymeric (CFRP) composites was investigated. Both strength and modulus were measured at room temperature dry, cold temperature dry, $-55^{\circ}C$, and elevated temperature wet, $82.2^{\circ}C$ on seven different laminate configurations consisting of $[0_6]_T$, $[90_{12}]_T$, $[0_{16}]_T$ and $[90_{16}]_T$ unidirectional laminates, $[{\pm}45]_{5S}$ angle-ply laminate, $[0/90_{12}/0]_T$ cross-ply laminate, a 36-ply laminate $[0/45/-45/45/-45/0]_{3S}$. Based on the experimental data presented, it is shown that the strength at cold temperature dry, $-55^{\circ}C$ is increased with the brittleness of fiber or matrix. Moreover, it is shown that both shear strength and modulus at elevated temperature wet, $82.2^{\circ}C$ are decreased by the cause of interfacial deterioration between fiber and matrix with moisture absorption.