• Journal of Energy Engineering
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• v.9 no.3
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• pp.157-162
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• 2000

기존의 IGCC의 장점인 고효율 플랜트의 특성을 살리기 위해 고온정제를 적용하는 경우 조건변화에 따른 플랜트 성능의 영향을 관찰하고자 본 연구를 수행하였다. IGCC에 고온정제 공정을 적용하여 구성한 모델은 연구 목적에 알맞은 범위의 건전성을 가진 것으로 나타났으며 기타 조건을 동일하게 설정한 경우 저온 정제 공정(MDEA amine) 적용에 비해 플랜트 효율이 약 2.7% 가량 상승하였다. 한편 동일한 고온정제 공정이라도 적용하는 흡수제를 zinc titanate에서 zinc ferrite로 달리 하는 경우 탈황제의 화학 반응상 특성 및 차이점으로 인해 연료가스의 발열량 변화를 유발하므로 결과적으로 약 0.5%의 플랜트 효율 손실이 발생함을 알 수 있었다. 또한 탈황 온도 350~$650^{\circ}C$ 사이의 온도범위에 대해 민감도 분석을 실행하였으며 민감도 분석 결과 전제 온도의 증가와 플랜트 효율은 정비례하지 않으며 50$0^{\circ}C$ 이상의 정제 온도를 적용한 경우는 거의 비슷한 효율을 나타내었다. 이와 같은 결과는 정제 온도를 증가시킴으로 인해 가스터빈에 공급되는 연료가스의 온도는 높아지지만 적용한 가스터빈의 출력 및 연소 온도가 제한되어 있어 고온정제를 적용함으로써 얻어지는 이득을 가스터빈에서 충분히 보상하지 못하고 한편으로 고온정제를 채택함으로써 저온정제 적용시 보다 syngas cooler에서 회수할 수 있는 헌열이 줄어듦으로 인한 증기 터빈 출력의 감소가 커지기 때문으로 분석되었다.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.111-121
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• 2001

Rockfall protection fences are used for diminishing rockfall damage in roads side slopes. In order to install the fences in effective way, the conditions of rock slopes and total predicted impact energy of fa11ing rock should be considered. However, the fences have been constructed without any consideration for lithology, height and slope angle of rock slope in Korea. In addition, the information about the performance of the protection fences, which should be evaluated by in-situ test or laboratory test in order to check out the practical use in the field, is not available. Therefore, in design manual for the rockfall protection fence, the specific details for the installation of this type of fence are not provided yet. The full sized rockfall in situ test was carried out for the calculation of falling energy of rock and the evaluation of the maximum energy absorbing capacity of fence. For this test, the rock slopes whose heights are about 20 m and dip angle of 65 degree, have been chosen. This is because those geometries are mean height and slope angle of most road cut slopes along Korean national highway. Based on the preliminary simulation procedure, four different sizes of concrete ball (0.7, 1.3, 2.3 and 4.3 ton) were prepared and flour different types of protection fence were constructed. The results of this test provide information about the maximum energy absorbing capacity of the fence, kinetic energy of rockfall and restitution coefficient, and these results can be utilized in the establishment of rockfall fence design and construction manual.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.4
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• pp.263-275
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• 1991

Studies on the annual performance of three different type of solar-absorption heat pump system (parallel type, series type, and generator type) are carried out by using the computer simulation. These include the calculation of solar energy from the solar collector, and the revision of computer package, developed by Oak Ridge National Laboratory, to predict the annual performance. Finally using weather data and load conditions, the annual performance are obtained. Results show that the annual operating costs of three solar-absorption heat pump systems are almost same values and 44% lower than that of the pure absorption heat pump system. The total annual input energys of solar-absorption heat pump systems are also about 44% lower than that of the pure absorption heat pump. The nominal size of the solar-absorption heat pump systems can be reduced to a value of 55% that of the pure absorption heat pump that would normally be specified under identical conditions.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.986-994
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• 2017

In this paper, $CO_2$ absorption of scrubber was tested for removal of high concentration $CO_2$. Liquid to gas ratio($18L/m^3$) and Superficial velocity(0.14 m/s) was determined through Lab-scale test. As flow rates increase 1, 2, 3, 4 and $5m^3/min$, $CO_2$ removal efficiency decrease 98.47%, 96.46%, 92.95%, 89.71% and 85.49%. Also, the scrubber operation made energy improvement(5.4%), energy saving(11.5 TOE/year) and greenhouse gases reduction(6.5 TC/year).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.1
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• pp.33-39
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• 2007

This paper is aimed at the development of a software that predicts the surface temperature profiles of three-dimensional objects on the ground by considering the spectral solar radiation through the atmosphere. The spectral solar radiation through the atmosphere is modeled by using the well-known LOWTRAN7 code which analyzes the detailed spectral transmission characteristics by considering the atmospheric gas layers. In this paper, the transient temperature distribution over a cylinder is calculated by using the semi-implicit method. The spectral radiative surface properties such as the absorptivity and emissivity of the objects are used to model the effects of the solar irradiation and the surface emission. Both the detailed spectral modeling and the simple total modeling for the solar radiation absorption show fairly good agreement with each other by showing less than 3% difference in surface temperature.

• Journal of the Korean Wood Science and Technology
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• v.36 no.1
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• pp.30-35
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• 2008

Degradation of mechanical properties of fire-killed Korean red pine has been investigated after death in 5 years period. Impact bending absorbed energy was the most sensitive property by elapsed time after forest fire. It is an indication of incipient decay of the wood and can be useful indicator to monitor any change of mechanical property of fire-killed tree after death. Degradation of mechanical properties was more pronounced in sapwood than heartwood. Impact bending absorbed energy was more reduced than any other properties in both sapwood and heartwood, while compressive strength was least impacted by elapsed time after forest fire. It is recommended that the fire-killed Korean red pine can be harvested in one year after the fire for industrial uses by considering decay and consequent changes of mechanical properties.

• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.647-656
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• 2002

High-strength steel in steel bridges is the key to achieving cost-efficiency because it facilitates lightweight construction and rationalizes structure. The future of high-strength steel is bright, with its use projected to expand. As such, it is necessary to evaluate precisely various factors affecting the process of fabricating high-strength steel, i.e., welding heat, strain hardening, and weldability and performance of the welded joints. This study therefore performed the maximum hardness test and y-groove weld crack test using welding processes such as SAW, FCAW, and GMAW, in order to investigate the welding performance and characteristics of welded Joints or high-strength steel produced in Korea such as SM570, POSTEN60, and POSTEN80. In addition, a series of welding tests was carried out to estimate the tensile strength, bending characteristics, absorbed energy, and hardness in welded joints.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.2
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• pp.55-66
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• 1999

Eight RC bridge plers have been made on a 1/3.4 scale model and have been tested in a quasi-static cyclic load so as to investigate their seismic performance. The ultimate objective of this experimental study is to investigate the hysteretic behavior of reinforced concrete plers, which have been widely used for urban transportation facilities in Korea. Improtant test parameters are hoop ratio, axial load, load pattern, and etc. And noninear behaviors of test columns have been evaluated through their yield and ultimate strength, energy dissipation, ductility and load-deflection characteristics under quasi-static cyclic loads. From the quasi-static tests on 8 bridge piers, it is concluded that energy dissipation, ultimate strength and curvature for a given displacement factor ${\mu}={\Delta}/{\Delta}_y$ are higher for the seismically designed columns than for the nonseismically designed columns.

• Journal of Energy Engineering
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• v.26 no.1
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• pp.23-27
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• 2017

An expander of an organic Rankine cycle is an essential component that significantly influences its entire performance and cycle efficiency. The inlet pressure and temperature of the expander used for the organic Rankine cycle are limited by the expander's mechanical properties and the characteristics of the working fluid. The organic Rankine cycle's output, heat absorption, and efficiency are altered by the inlet pressure and temperature of the expander. In this study, a theoretical comparative analysis was conducted on an organic Rankine cycle's performance changes, which are dependent on the inlet condition of the expander. The working fluid is an R134a refrigerant, and the expander is a positive-displacement type.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.2
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• pp.165-172
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• 2014

Experiments were conducted to identify basic characteristics of $CO_2$ capture using a spray tower with a single nozzle. Results were evaluated in terms of $CO_2$ saturation which is the main determining factor of regeneration energy, and capture efficiency under various operating conditions. Changes in the capture efficiency under various conditions are well expressed as a monotone increasing function of the relative solvent $(NH_3):CO_2$ flow rate. Although changes in $CO_2$ saturation are also well described as a function of the $NH_3/CO_2$ flow rate ratio, these are expressed as a monotone decreasing function, in contrast with the increasing function of $CO_2$ efficiency. In recent research on the relationship between $CO_2$ saturation and capture efficiency, $CO_2$ saturation was found to decrease when capture efficiency increased. In conclusion, the results show that the amount of solvent used for achieving high capture efficiencies is excessive, as is the amount of regeneration energy needed.