• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.562-563
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• 2008

경쟁적 전력시장에서는 이익주체의 다양화로 송전망확장은 개별 시장참여자의 경제적 편익에 큰 영향을 미칠 수 있다. 송전설비 투자계획은 미래 전력 시장 및 계통의 예측을 바탕으로 하기 때문에 예측의 불확실성에서 발생하는 설비투자의 과잉.과소투자의 최소화 방안이 필요하다. 따라서 본 논문은 송전망확장사업의 경제적 가치를 평가하는 방법에 대해 연구였고 미래 시장 및 계통의 불확실성을 반영하기 위해 전력수요와 연료가격의 과거 예측오차의 표준편차를 이용한 예측값의 확률밀도함수의 모델링 방법을 이용한 송전망확장의 경제성 평가 방법을 제시한다. Monte Carlo Sampling을 이용, 송전망확장으로 인한 시장참여자의 경제적 편익 변화의 기대값과 편익 변화의 범위를 산출함으로써 설비투자의 리스크와 잠재효과에 대해 분석한다.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.4
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• pp.421-429
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• 1997

This study is theoretically examined the influences on the performance of diesel engine super¬charged by exhaust gas turbine with the change of excess air factor, admission ratio, total efficien¬cy of turbine and compressor, scavenging pressure ratio, and scavenging temperature. In this study, all calculations are carried out by computer, and the theoretical engine performance is com¬pared with the actual engine performance which is offered from engine manufacturer. Following results are acquired by this study. The mean effective pressure is increased with decrease of excess air factor or increase of scavenging pressure ratio. As the admission ratio or total efficiency of tur¬bine is increased, the mean effective pressure is increased but the specific fuel consumption is decreased. Mean calculation error compared with the actual engine performance is under 5 per¬cents, therefore, this calculation method can be used in the design of diesel engine.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.2
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• pp.44-52
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• 1993

In this study, the characteristics of decreasing exhaust gas of diesel engine was examined in dual fuel method by using commertial LPG for automotive. LPG was supplied to engine intake port by fumigation method and flow rate was controlled by using the needle valve. LPG supply ratios were 0, 20, 30% of total fuel amount to be supplied to engine by mass base. We investigated the effect of LPG supply ratio on exhaust gas concentrations related to excess air ratio and engine load at 1600, 1800, 2000 rpm. Soot concentration decreased about 30% in proportion to the increase of the LPG supply ratio. NOx concentration decreased in proportion to the increase of the LPG than diesel only and the increase rate was higher at low engine load. BSFC(Brake specific fuel consumption) was lower in proportion to the increase of the LPG supply ratio at high engine load and to the decrease of LPG supply ratio at low engine load.

• Journal of Power System Engineering
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• v.6 no.2
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• pp.12-17
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• 2002

Recently, the world is faced with very serious problems related to the air pollution due to the exhaust emissions of the diesel engine. So, many of researchers have studied to reduce the exhaust emissions of diesel engine. This study was investigated for various exhaust emissions according to operating conditions in a turbocharged D.I. diesel engine. As a result of experiments in a test engine, the $CO_2\;and\;NO_x$ increased with increasing load, the $CO_2$ and CO decreased with increasing charge air pressure in manifold, the CO decreased with increasing cooling fresh water temperature, and the $NO_x$ decreased with worming cooling fresh water before engine start.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.107-113
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• 2002

LPG has been well known as a clean alternative fuel for vehicles. Recently, several LPG engines for heavy duty vehicles have been developed, which can replace some diesel engines that are one of the main sources for air pollution in the urban area. Because cylinder bore of heavy duty LPG engine is larger than that of gasoline, the study of knock characteristics of LPG engine are needed. In this study, the knock characteristics were investigated with various engine speed, air excess ratios and LPG fuel compositions. Experimental results indicated that the Knock occurrence probability decreases with increasing engine speed and propane fraction of fuel. The Knock occurrence probability is highest at excess air ratio of 1 and decreases as the mixture strength became leaner.

• Life and Agrochemicals
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• v.29 no.10
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• pp.10-13
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• 2008

2008년 3월 현재 세계 인구는 약 66억 7000만 명으로 나타났다. 이에 그치지 않고 세계인구는 계속 증가하여 2050년에는 90억, 그리고 2100년에는 100억 명이 될 것이라는 것이 UN의 예측이다. 인구만 증가하는 것이 아니다. 당연히 인구증가에 따른 주택, 도로, 기타 소회간접시설이 확충되어야 하기 때문에 농지가 감소하게 된다. 보다 효율적인 식량 증산방법이 없다면 식량부족문제가 더욱 심각해질 것이라는 것은 그렇게 이해하기 어려운 얘기가 아니다. 그러나 우리나라 국민들은 식량부족 위기에 대해서는 대체로 둔감하다. 그저 돈만 있으면 무엇이든지 구하지 못할 것이 없다는 생각을 가지고 있다. 그 이유가 뭘까? 과거 60년대까지는 식량부족 및 화석연료(석탄이나 석유)의 고갈에 대한 위기감이 매우 고조되어 있었으나 그러한 위기가 현실로 나타나지 않았다. 뿐만 아니라 우리나라는 현재 1980년대 중반 이후 산업발달의 결과로 많은 부(富)가 창출되어 식량 및 에너지의 풍요를 누리고 있다. 오히려 식량부족보다는 식품의 과잉섭취로 인한 비만이나 성인병 등의 부작용 개선이 더 시급한 현실상황에서 식량부족 문제는 다른 나라의 일로 생각할 수도 있다. 그러나 농지가 절대적으로 부족한 우리나라로서는 안정적인 식량공급을 위한 방안의 도출이 중요한 과제임에 틀림이 없다.

• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.59-66
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• 2018

Using hydrogen fuel is expected to be suitable as a reciprocating internal combustion engine with heightened interest in HALE(High Altitude Long Endurance) UAV(Unmanned Aerial Vehicle). Hydrogen is hightest energy density per mass so it can continue to charge for long periods of time and have positive part of the environmental effects. However, it is estimated that there is less research on hydrogen fuel engine currently applied, and many studies need to be done. Depending on the operation, there are factors that result in supercooling due to reduced radiation or reduce cooling performance due to low air density. Therefore, the experiment was to change the temperature of the cooling water and investigate the effect on engine combustions. The limitation of the stable operation range due to backfire is dominated by the excess air ratio rather than the effect of the cooling water temperature change. When the cooling water temperature increases, the volumetric efficiency decreases and the torque decreases. As the cooling water temperature decreases, the heat loss was increased and consequently the thermal efficiency was decreased.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1033-1040
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• 2011

The premixed burner is a very strong candidate for using household boiler burner system because it has high efficiency, low emission and can be used in compact boiler system. Usually, household boiler burner systems use a Bunsen burner, which consists of an inner rich premixed flame and fuel burned completely by a secondary air supply. It has a relatively long flame length and operates in a high excess of air, so it is difficult to fit such a burner into a high efficiency compact boiler. In this paper, the characteristics of a premixed combustion burner for surface media such as metal fiber, ceramic, and SUS fin were evaluated. In particular, the flow velocity over the burner surface for the cold flow characteristics of the surface material were measured and adjusted. The combustion tests were carried out by taking pictures of the flame and measuring the flame temperature. The amounts of CO and NO were measured and the characteristics of the surface burner materials, combustion chamber, and heat exchangers were evaluated for various excess air ratios and heating values.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.860-865
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• 2012

Although biomass syngas is very low calorific gas, it is utilized by means of dual fuel combustion technology in the fields of industrial furnace and boiler as a substitute oil technology. The basic structure of duel fuel combustion burner is designed so that low caloric gas fuel is supplied around an oil burner in the middle. In the present study, three types of mixing burners were manufactured to conduct performance experiment. Low caloric gas was evenly distributed around the oil burner and the method of changing the angle of gas nozzle was applied. CO generation decreased according to the increase of the amount of air for combustion. In addition, the shapes and colors of flame changed according to the proportions of gas and oil used. Remained flame after combustion was from the lack of atomization at the exit of oil burner. Although it was difficult to maintain the optimum air ratio due to different required air ratio for oil and syngas, stable combustion was able to maintained within excess oxygen concentration of 4.7~8.2%. From this study, it was shown that the oil atomization at the exit of fuel oil nozzle was promoted by the increased rate of syngas combustion and the CO concentration in flue gas lower than only fuel oil combustion.

• Journal of Convergence for Information Technology
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• v.11 no.7
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• pp.111-117
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• 2021

This research work is to suggest the experimental results capable of solving an initial unsuitability of combustion and environment in a constant volume combustion chamber by using LFG(Land Fill Gas) which consists of 40% CO₂ and 60% CH₄. The experimental condition is set as 0.9~1.6 of air-fuel ratio, 3bar of combustion pressure, 25℃ of room temperature, methane for using gas, and 2.5~4.5 of Pre-chamber hole sizes. As a result, it can be seen that diffusion of initial flame is significantly increased by M3.0 model comparing with other one. The reason for the characteristics is that orifice effect is extremely improved by 0.9, 1.0, and 1.2 of air-fuel ratio comparing with other one. Consequently, this experiment is shown that M3.0 model is partially capable of improving combustion performance than a conventional ignition plug in case of applying to LFG with Pre-chamber design.