• Resources Recycling
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• v.19 no.3
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• pp.24-32
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• 2010

In the present work, a new separation system with rotating rakes has been developed to separate the film-based plastics from the recyclable materials, and environment assessment is also carried out during operation of the device. Capacity of the device was about 5.3 ton/hr at a rakes rotation speed of 26.0 rpm (the number of rakes in the 1st, 2nd and 3rd trials were 39, 52 and 48, respectively) and a belt conveyor speed of 38.5m/min, which satisfied the initial design capacity (5.0 ton/hr). Recovery ratio and purity of the plastic films were 92.6% and 96.5%, respectively at a rotation speed of 28 rpm. The levels of noise, vibration and particulate emission were below material standard regulatory limits. Plastic refused fuel (RPF) was also prepared with the recovered films. The calorific value and chlorine content of the prepared RPF were 9,740 kcal/kg and 0.18%, respectively which satisfy the first grade quality specification of the Korean RPF standard. As a result of this work, recovery of energy resources from the municipal solid waste is possible by adopting the developed separation device.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.181.1-181.1
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• 2010

기후변화의 주요인이 되는 온실가스 감축을 목표로 화석연료를 대체하기 위한 대체 에너지 개발을 위한 많은 노력이 진행되고 있다. 풍력 에너지와 같은 신재생에너지는 이러한 하나의 해결 수단이 될 수 있으며 풍력 에너지 사업의 활성화를 위해서는 정확한 풍력 정보 제공이 우선이다. 풍력-기상자원지도는 풍력 발전에 유용한 정보 제공을 위한 목적으로 중규모 수치 모델을 이용하여 작성된다. 본 연구에서는 중규모 수치 모델의 정확도 향상을 위한 자료동화 방법으로써 Four-Dimensional Data Assimilation (FDDA) 방법을 이용한다. 풍력-기상자원지도는 공간분해능 1 km 해상도로 개발된다. 풍력-기상자원지도는 1998-2008년까지의 평균적인 상태에 대하여 모의를 하기 위하여 통계적인 방법으로 11년 기간의 평균과 유사한 기간을 선정하였다. 풍력-기상자원지도는 연 평균, 월 평균 풍속과 주 풍향, 주풍향 발생 비율 등의 정보를 제공한다. 우리나라 풍속의 평균 분포는 내륙 산악지역, 남해안, 제주도에서 강풍이 발생하며 주 풍향은 대체로 북서풍이다. 주 풍향의 발생비율은 산악 지역과 남 동해안에서 높아 풍력 발전의 최적지 정보를 제공한다. 1 km 해상도의 모델과 관측의 오차는 서해안 등의 해안지역보다 강원 산악지역에서 오차가 더욱 증가하였다. 이러한 산악 지역의 오차는 복잡한 지형에서는 1km 미만의 수 백 m 해상도 수치모의가 필요함을 지시한다. 따라서 본 연구에서는 WRF-LES 모형을 이용하여 333m 해상도의 기상자원지도를 개발한다. 333m 해상도의 자원지도 영역은 강원도 지역에 대하여 모의되었다. 333m 해상도의 풍속 분포는 1km 해상도의 풍속 분포와 비교하였을 때 풍속의 분포가 보다 세밀하게 표현되었다. 정량적인 검증을 하였을 때 관측소에 따라 차이는 있었으나 1km 해상도에서 과대 모의된 풍속의 분포가 현저히 개선이 되었으며, 시간적인 경향도 잘 일치함을 보였다.

• Journal of Energy Engineering
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• v.19 no.4
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• pp.240-245
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• 2010

In this study, characteristics of wood pellet gasification was studied using a Two Stage Gasifier which is consisted of pyrolysis reactor and ultra high temperature reformer. The average yields of $H_2$, $CH_4$, CO, $CO_2$ were 16.7, 11.3, 37.2, 26.6 L/mim, conversion rate from biomass to gas was 65% in pyrolysis reactor and gas yields in reformer were 55.4, 0.8, 120.8, 56.8 L/mim, respectively. The hydrogen flow rate from reformer is obtained 360.1 L/hr. The most of $CH_4$ was decomposed from 12.3 to 0.3 vol.% while $H_2$ is from 18.2 to 23.7 vol.% in reformer by methane dry reforming, Boudouard reaction, oxidation and/or steam reforming. The amount of $H_2O$ generated by hydration reaction from reformer was 1111.8 g, its accelerated conversion of $CH_4$ to other products. The conversion rate from $CH_4$ to other Compounds was 97.2%. Cold gas efficiency was 53.2%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.713-721
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• 2014

In Europe and USA, new programs called GRC(Green Rotorcraft) and SRW (Subsonic Rotary Wing program) respectively, have been currently underway for developing the next generation rotorcraft. The final goal is to develope fuel-efficient/environmental-friendly tilt-rotor civilian rotorcraft, which can partly replace short-range regional aircrafts. Also for safe operation, the new rotorcraft technology is cooperated with the new air transport management(ATM) system, called SESAR(Single European Sky ATM Research) and NextGen(Next Generation Air Transport System) in Europe and USA. In addition to achieve the final goal, the tilt-rotor aircraft, they are trying to improve the performance of conventional helicopters by adopting more efficient propulsion system, active rotor system, and reducing internal and external noise. Especially in GRC program of Europe, the environmental factors such as noise, fuel efficiency, reduction of emission gas(CO2, NOx), are focused for the new technologies.

• Resources Recycling
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• v.23 no.4
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• pp.37-46
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• 2014

Carbon dioxide generated from construction materials and construction material industry among the fields of construction is approximately 67 million tons. It is about 30% of the carbon dioxide generated in the fields of construction. In order to reduce carbon dioxide in the fields of construction, it is necessary to control the use of fossil fuel consumed and decrease carbon emission by reducing the secondary and tertiary curing generating carbon dioxide in construction material industry. Therefore, this study manufactured mortar by having cement as the Plain and substituting three binding materials up to 50% and then adopted different curing methods to analyze congelation and strength characteristics. Test results for strength property by changing binding materials showed that specimens with blast furnace slag, CSA 15% and CAMC 5% resulted in positive effect for strength.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.443-450
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• 2008

Efficient use of low rank coals (LRC) have been investigated as a method to cope with recent high oil price. Among the coals used in industry, lignite and sub-bituminous coals are belong to the LRC, and have abundant deposit and are distributed worldwide, but high moisture contents and self ignition properties inhibits their utilization. In this paper, chemical coal cleaning to produce ash-free coal from LRC has been investigated. Two technologies, that is, UCC(Ultra Clean Coal) process removing ash from coal and Hyper Coal process extracting combustibles from coal were compared with. UCC process has merits of simple and reliable when it compared with Hyper Coal process, but the remaining ash contents werehigher than Hyper Coal. Hyper Coal has ash contents under the 200ppm when raw coal is treated with appropriate solvent and ion exchange materials to remove alkali materials in extracted solution. The ash-free coal which is similar grade with oil can be used as alternate oil in the industry, and also used as a high grade fuel for IGCC, IGFC and other advanced combustion technology.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.4
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• pp.337-344
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• 2017

The demand of liquified natural gas is increasing due to environmental issues. This reason has resulted in increasing the capacity of liquified natural gas cargo tank. The Mark-III type primary barrier directly contacts liquified natural gas. Also, the primary barrier is under various loading conditions such as weight of liquified natural gas and sloshing loads. During a ship operation, various loads can cause fatigue failure. Therefore, the fatigue life prediction should be evaluated to prevent leakage of liquified natural gas. In the present study, the fatigue analysis of insulation system including primary barrier is performed using a finite element model. The fatigue life of primary barrier is carried out using a numerical study. The value of principle stress and the location of maximum principle stress range are calculated, and the fatigue life is evaluated. In addition, the effects on the insulation panel status and the arrangement of knot or corrugation are analyzed by comparing the fatigue life of various models. The insulation system which has best structural performance of primary barrier was selected to ensure structural integrity in fatigue assessment. These results can be used as a design guideline and a fundamental study for the fatigue assessment of primary barrier.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.517-534
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• 2021

Hydrogen fuel is emerging as an new energy source to replace fossil fuels in that it can solve environmental pollution problems and reduce energy imbalance and cost. Since hydrogen is eco-friendly but highly explosive, there is a high concern about fire and explosion accidents of hydrogen fueled vehicles. In particular, in semi-enclosed spaces such as tunnels, the risk is predicted to increase. Therefore, this study was conducted on the applicability of the equivalent TNT model and the numerical analysis method to evaluate the hydrogen explosion pressure in the tunnel. In comparison and review of the explosion pressure of 6 equivalent TNT models and Weyandt's experimental results, the Henrych equation was found to be the closest with a deviation of 13.6%. As a result of examining the effect of hydrogen tank capacity (52, 72, 156 L) and tunnel cross-section (40.5, 54, 72, 95 m²) on the explosion pressure using numerical analysis, the explosion pressure wave in the tunnel initially it propagates in a hemispherical shape as in open space. Furthermore, when it passes the certain distance it is transformed a plane wave and propagates at a very gradual decay rate. The Henrych equation agrees well with the numerical analysis results in the section where the explosion pressure is rapidly decreasing, but it is significantly underestimated after the explosion pressure wave is transformed into a plane wave. In case of same hydrogen tank capacity, an explosion pressure decreases as the tunnel cross-sectional area increases, and in case of the same cross-sectional area, the explosion pressure increases by about 2.5 times if the hydrogen tank capacity increases from 52 L to 156 L. As a result of the evaluation of the limiting distance affecting the human body, when a 52 L hydrogen tank explodes, the limiting distance to death was estimated to be about 3 m, and the limiting distance to serious injury was estimated to be 28.5~35.8 m.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.8
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• pp.733-741
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• 2013

This is the first paper on the combustion characteristics of landfill gas in a constant volume combustion chamber for a large displacement volume commercial engine, and it discusses the fundamental characteristics of fuel from the viewpoint of thermochemistry and thermodynamics and compares these results with experimental ones. The results show that the final pressures obtained from theoretical analysis vary under the same heating value owing to the change in the constant volume specific heat owing to the difference in the burned gas composition according to the fuel gas compositions; furthermore, the stoichiometric ratios and trends of analytical and experimental pressures coincide very well, although some minor differences are observed between the two. The root cause of the difference is the heat transfer, which changes the specific heat and lowers the temperature considerably, in the real combustion process. In addition, the large chamber volume and ignition position promote the heat transfer to the wall. Finally, the fuel conversion efficiency increases as the methane mol fraction decreases, and it is maximum when the stoichiometric ratio ranges from 0.8 to 0.9. These increases due to the composition and stoichiometric ratio could sufficiently compensate the decrease due to the specific heat ratio drop, LFG might be more advantageous than pure methane in a real engine.

• Journal of IKEEE
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• v.23 no.1
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• pp.334-337
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• 2019

In response to the increasing demand for energy, research and development of next-generation energy is actively carried out around the world to replace fossil fuels. Among them, the specific gravity of solar power generation systems using infinity and pollution-free solar energy is increasing. However, solar power generation is so different from solar energy that it is difficult to provide stable power and the power production itself depends on the solar energy by region. To solve these problems in this paper, we have collected meteorological data such as actual regional solar irradiance, precipitation, temperature and humidity, and proposed a solar power output prediction system using logic-based fuzzy Neural Network.