• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.1
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• pp.225-228
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• 2004

Optimization of fluidized bed granulating conditions for yield, bulk density, and tapped density of powdered milk was determined using response surface methodology. Yield of powdered milk was greatly affected by feeding rate of water, and bulk density and tapped density could be reduced by decreasing of atomization pressure. The optimum conditions for fluidized bed granulating of powdered milk were predicted with 6$0^{\circ}C$ of inlet air temperature, 16 mL/min of feeding rate, and 2.1 bar of atomization pressure. Also 94% of yield 0.350 g/㎤ of bulk density, and 0.446 g/㎤ of tapped density of powdered milk could be obtained by the optimum granulating conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.18-24
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• 2015

An experimental investigation was conducted to figure out the effects of the inlet air temperature on the combustion efficiency using the fuel grains which were highly loaded with boron carbide. The results showed that the normalized combustion efficiency increased with the inlet air temperature, apparently the result of enhanced combustion of the boron particles. Even though the combustion efficiency is increased, the overall efficiency through the semi-empirical method, is decreased with the increasing inlet air temperature. Brayton cycle analysis has been performed using the heat input parameter and combustor Mach number, those two parameters are important role for the performance and similar trends are shown at the experimental results.

• Journal of the KSME
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• v.23 no.6
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• pp.427-433
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• 1983

내연기관의 성능은 실린더에서 연료의 화학에너지가 열에너지로 얼마만큼 빠르고 완전하게 변화하느냐에 좌우된다. 이를 위해서는 실린더 내에서 뜨거운 압축공기와 연료의 혼합 및 증기화가 요구된다. 엔진의 출력은 매 사이클당 흡입.압축할 수 있는 공기량에 좌우되므로 연소의 해석을 위해서는 실린더 내의 공기유동, 연료의 분무 및 연소과정을 이해 해야한다. 배기와 엔진효율의 요구성때문에 희박 혼합기 또는 EGR (exhaust gas recirculation)이 필요하게 된다. 그러나 희석이 크면 낮은 연소온도, 낮은 층류흐름속도와 화염전면의 낮은 난류강도 때문에 연소기간이 증대하게 된다. 실제로 희박의 증가는 실화 또는 긴 연소 지연기간, 사이클 마다의 연소맥동현상, HC배기의 증가등을 초래하게 된다. 이러한 저온연소의 단점들은 연소상태를 안정시키고 연소량을 증대시키는 공기의 유동을 이용해서 해결 될 수 있다. 최근에는 선회류와 난류의 강도를 증가시켜서 빠른연소(fast burning)를 이루고 있다. 선회류와 난류의 강도를 증대시키는 가장 중요한 2가지 방법은 흡입포트(port), 매니홀드(manifold)설계이다.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.95-101
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• 2004

An experimental investigation was conducted to investigate the effects of the equivalence ratio and air mass flux on the combustion efficiency in a solid fuel ramjet used fuel grains which were highly loaded with boron carbide. Combustion efficiency increased with increasing equivalence ratio (grain length), and decreasing air mass flux. Higher inlet air temperature produced higher combustion efficiencies, apparently the result of enhanced combustion of the larger boron particles those burn in a diffusion controlled regime. Short grains which considered primarily of the recirculation region produced larger particles and lower combustion efficiencies. The result of the normalized combustion efficiency increased with inlet air temperatures coincident with the result of the Brayton cycle thermal and the total efficiency relating to the heat input.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.38-45
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• 2001

Environmental protection on the ocean has been interested and nowadays the International maritime organization(IMO) has advanced on the prevention of air pollution from ships. This study presents the emission characteristics of 4 stroke propulsion diesel engine in E2 cycle (constant speed) and E3 cycle (propeller curved speed). Also the effects of important operating parameters in terms of intake air pressure and temperature, and maximum combustion pressure are described on the specific emissions. Emissions measurement and calculation are processed according to IMO technical code. The results show that NOx emission level in E3 cycle is higher than E2 cycle due to lower engine speed and lower maximum combustion pressure by retarding fuel injection timing. Intake air temperature has strong influence on NOx emission production. And CO, HC emissions are not affected by maximum combustion pressure and intake air pressure and temperature.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.3
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• pp.457-465
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• 2004

Environmental protection on the ocean has been interested and nowadays the International Maritime Organization(IMO) has advanced on the prevention of air pollution from ships. This study presents the performance and the emission characteristics of 4 stroke marine diesel engines for generation application in D2 cycle(IMO mode). The effects of important operating parameters, such as intake air pressure. intake air temperature and maximum combustion pressure on NOx emissions were also described. Emissions measurement and calculation are processed according to IMO Technical Code. The results show that the maximum combustion pressure by fuel injection timing control and intake air temperature has strong influence on NOx emission production. But NOx emission is not affected by intake air pressure and exhaust gas back pressure.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.6 no.1
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• pp.36-43
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• 1977

온도분포, 농도분포를 가미한 비압축성 유체의 기초방정식을 토출$\cdot$흡입이 있는 2차원 폐공간에 적용하고 시간공간에 차분근사로써 얻은 수치해에 대하여 서술했다. 이와같은 방법에 대해서는 미해결의 요소가 많이 있으나, 여기서는 토출풍속$\cdot$온도차$\cdot$격자수를 변화시킬 때의 해가 변화하는 모양을 계산예에 따라서 보고한다.

• Journal of Power System Engineering
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• v.10 no.1
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• pp.19-24
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• 2006

This work treats a controlled auto-ignition (CAI) single cylinder gasoline engine, focusing on the extension of operating conditions. The fuel was injected indirectly into electrically heated inlet air flow. In order to keep a homogeneous air-fuel mixing, the fuel injector was water-cooled by a specially designed coolant passage. The engine performance and emission characteristics were investigated under the wide range of operating conditions such as 40 in the air-fuel ratio, 1000 to 1800 rpm in the engine speed, 150 to $180^{\circ}C$ in the inlet-air temperature, and $60^{\circ}$ BTDC in the injection timing. The ultra lean-burn with self-ignition of gasoline fuel by heating inlet air was achieved in a controlled auto-ignition gasoline engine. It could be also achieved that the emission concentrations of carbon monoxide, hydrocarbons and nitrogen oxide significantly reduced by CAI combustion compared with conventional spark ignition engines.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.377-380
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• 2007

Large Eddy Simulation has been conducted to investigate both stable and unstable flame structures in a swirl turbulent combustor. While a flame is stabilized with periodic dynamic structure at 600K, a slight increase in the flame temperature of inlet mixture, 660K, lead to bifurcation of flame at swirl angle 45 degrees. It was observed that both swirl number and mixture temperature affect a flame bifurcation and the former is a major parameter. One major mechanism contributing to the unstable flame is that the local flame speed overshadows the local flow velocity near the wall of the combustor.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.2
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• pp.59-67
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• 2017

The aim of this experiment was to investigate the effect of air suction rate (SR) during the composting process of swine manure mixed with sawdust used as a bulking agent. In the 25 L composting reactors, the suction rate (SR) was at four different treatment levels (100%, 200%, 300%, 400%), and were fixed on the based on constant aeration rate into the composting mixtures. The temperature reached to thermophilic phase within 2 days and it was maintained up to the $5^{th}$ day of the composting process in all reactors and then gradually decreased to room temperature at the end of the composting process. The moisture content (MC, %) of the initial mixtures was 64.27%, and it was reduced to 38.4, 33.08, 14.59 and 11.93 in the different suction rate of 100%, 200%, 300%, 400%, respectively in the end process. During the composting, the level of pH was increased from 6.83 to 8.67 and it gradually decreased to 7.56 in 100% and 200%(SR). At the same time, the pH values were reduced only up to 8.19 at 300%, and 8.08 at 400%(SR), showing that suction strengths of 100% and 200% were the better option for composting than those of 300% and 400%. The total Kjeldahl nitrogen (TKN) of initial composts mixtures was 2.3% and were changed in 3.3, 3.1, 2.5, and 2.3% at the end of the composting period from the 100%-400% (SR) variations respectively. These results also indicated that 100% and 200% (SR) were more affected by the dry mass loss as $CO_2$ and water evaporation. The initial value of C/N ratio was 25.17 and were significantly reduced to 11.88, 11.97, 14.31, and 14.72 at the end of the experiment, respectively from the 100%-400% (SR) variations. These results suggest that the suction rate (SR) of 100% and 200% relative to constant air supply would be the optimal conditions to produce high-quality compost.