• Journal of the KSME
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• v.20 no.3
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• pp.201-203
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• 1980

최근 전력수요의 증대와 석유위기에 따라 화력발전소의 연료 cost의 상승때문에 선진국에서는 대용량의 원자력 발전소의 건설이 증대되고 있으며, 원자력발전의 빈하조절의 난점 때문에 잉 여발력의 발생이 예상되는바 이들 잉여전력의 소화와 발전소의 효율향상, 철두전력의 공급상 변화변동에 대한 속응성이 가장 우수한 앙수발전소의 고려는 불가피 하게 된다. 양수발전은 전 력의 소비가 가장적은 심야에 잉여전력을 동력으로 이용하여 pump로 하부저수지에 저장되어 있는 물을 비교적 높은 곳에 자리잡은 상부 저수지에 양수한 다음 양간 또는 야간의 접두번하 시(peak time)나 계통사고때 이물을 다시 하부 저수지에 방유하면서 발전하는 점두변히 담당 발전방식이다. 따라서 양수발전은 peak 전력공급 뿐 아니라 심야의 값싼 전력을 소화 시키기 때문에 대용량 기저발전소(화력및 원자력)의 이용율을 향상 시켜주는 두가지 구실을 하게 된다.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.762-767
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• 2016

High thermal efficiency and the ability to use various types of fuel are a few of the many advantages of diesel engines. However, a major disadvantage is that their exhaust emissions are more harmful to humans and the environment than that of conventional engine. Consequently, the provisions of the international emissions standards for diesel engine equipped passenger cars, commercial vehicles, and ships have become more stringent. These standards include the EU Euro 6, the IMO MEPC Tier 3, and the US EPA Tier 4. Ryu et al. published a study that applied fuel additives to two-stroke diesel engines. In this study, a four-stroke diesel engine using diesel oil for a generator is utilized as the test subject, and an experiment is performed to verify whether fuel additive can be used to improve performance and exhaust emissions. In addition, this experimental study presents research results for the application of fuel additives in both two-stroke and four-stroke diesel engines. The experimental results were compared and analyzed by placing an oil-soluble calcium-based organometallic compound in diesel oil. The results confirmed that the addition of fuel additive improved the performance (fuel consumption rate, exhaust gas temperature) and exhaust emissions (NOx, CO) of the diesel engine.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.1
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• pp.94-100
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• 2019

This study was conducted on a high-temperature/high-pressure washer in which low-pressure cold water in a boiler is heated to a temperature range of $70{\sim}80^{\circ}C$ by supplying diesel combustion heat. The high-temperature water is sent to a compressor to increase its pressure to 200 bar, thereby making high-temperature/high-pressure water, which is sprayed through a spray nozzle. In the results of this study, the spray temperature of the high-pressure washing was shown to be the highest when the ratio between the actual amount of combustible air and the theoretical amount of air was 1:1 and the energy consumption rate of the low-pressure boiler type high-pressure washer was shown to be much lower than that of the high-pressure boiler type high-pressure washer.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.23-30
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• 2010

Trends of the automotive market require the application of new engine technologies, which allows for the use of different types of fuel. Since ethanol is a renewable source of energy and it contributes to lower $CO_2$ emissions, ethanol produced from biomass is expected to increase in use as an alternative fuel. It is recognized that for spark ignition (SI) engines ethanol has advantages of high octane number and high combustion speed. In spite of the advantages of ethanol, fuel supply system might be affected by fuel blends with ethanol like a wear and corrosion of electric fuel pumps. So the on-board hydrogen production out of ethanol reforming can be considered as an alternative plan. This paper investigates the influence of ethanol fuel on SI engine performance, thermal efficiency and emissions. The results obtained from experiments have shown that specific fuel consumption has increased by increasing ethanol amount in the blend whereas decreased by the use of hydrogen-enriched gas. The combustion characteristics with hydrogen-enriched gaseous fuel from ethanol reforming are also examined.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.137-143
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• 2012

Currently, in order to meet the reinforced emissions regulations for harmful exhaust gas including carbon dioxide ($CO_2$) as a greenhouse gas, technologies for reducing $CO_2$ emission and fuel consumption are being developed. Gasoline direct injection (GDI) systems have the advantage of improved fuel economy and higher power output than port fuel injection gasoline engine systems. The aim of this study is to examine the performance and emission characteristics of a lean burn GDI engine equipped with spray-guided-type combustion system. Stable lean combustion was achieved with a late fuel injection strategy under a constant operating condition. Further improvement in specific fuel consumption is possible with the introduction of multiple fuel injection strategies, which also increases hydrocarbon (HC) and nitrogen oxide ($NO_x$) emissions and decreases carbon monoxide (CO) emission.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1050-1056
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• 2010

Diesel engines introduce only air into the cylinder, and the air is high lycompressed. Fuel is directly injected into the combustion chamber in high temperature and pressure. Therefore diesel engines have high thermal efficiency because of the high compression ratio, while having high level of particulate matter and nitrogen oxide emissions because of the direct fuel injection. Many technologies have been developed to reduce particulate matter and nitrogen oxide emissions from diesel engines. One of the technologies is hydrogen fuel introduced into the combustion chamber with diesel fuel. In this thesis tiny amount of hydrogen is supplied into the combustion chamber in order to enhance the combustion performance. The engine, in which hydrogen is introduced, is tested. There are 20 test conditions given as 5 torque values of 100%, 75%, 50%, 25%, 0%, and 4 engine speeds of 700rpm, 1000rpm, 1500rpm and 2000rpm for the two cases with or without hydrogen addition. Maximum torques and Idle torques at each engine speed are measured, then the torque values are divided into 4 levels with 25% increasing step. The result shows that the fuel consumption, smoke, CO are reduced while the NOx emission is slightly increased, and the hydrogen addition has not a great effect on the performance at low loads but a great effect at a maximum load.

• Journal of Energy Engineering
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• v.25 no.2
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• pp.29-36
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• 2016

In this study, diesel/natural gas dual-fuel engine was studied numerically using DoE method. The engine is CI engine for power generation and modelled by 1-D simulation GT-power. The combustion and emission characteristics were analyzed as a function of IVO, IVC and the ratio of natural gas to total fuel enegy. As the proportion of natural gas increases, the BSFC(Brake specific fuel consumption) is increased and BSNOx(Brake specific NOx) is decreased. If specific valve timing to improve the BSFC is applied to the engine, the BSFC is decreased by 1% and simultaneously BSNOx is decreased by 36%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.953-959
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• 2015

The global warming caused by consumption of fossil fuel and energy has been interested. Therefore, several policies and regulations have been discussed to reduce greenhouse gas emission and effective energy consumption. The construction industry that takes 45% of energy consumption makes efforts to develop green construction methods and materials and reuseable energy. However, there is no common definition to calculate greenhouse gas and database in the construction industry. Especially, transportation infrastructure like road, railway, harbor, and airport consumes 21% energy of construction facilities. Therefore, this paper develops the causal relationship to define performance of sustainable road construction and maintenance. The performance indices are grouped into economic, social, and envirionmental impacts. Then, the causal map is developed based on survey results of construction experts. This will provide the baseline to evaluate the performance of sustainable construction and to establish the objective goals.

• Monthly Duck's Village
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• s.92
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• pp.50-59
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• 2011

2008년 급등하였던 국제곡물 가격은 209년 들어 하락하여 2010년 상반기까지 안정세를 보였으나, 기상악화로 인한 구소련 지역의 밀 생산 감소로 러시아가 수출 금지 조치를 취하면서 2010년 7월부터 밀 가격 급등을 시작으로 현재까지 강세를 보이고 있다. 옥수수 국제 가격 상승은 사료비 상승의 주된 요인으로 작용하여 축산 농가의 수익성을 악화시키고, 밀과 대두 국제 가격 상승은 이를 원료로 하는 가공품 가격 상승으로 이어져 소비자들의 부담으로 연계된다. 따라서 본고에서는 2008년의 애그플레이션 경험을 토대로 최근의 국제곡물 가격상승 원인과 2011년 상반기 국내 물가에 미치는 영향을 분석하고, 시사점을 제시하였다. 최근의 국제곡물 가격 상승은 생산 감소, 수요 증가, 곡물 선물 투기 증가에서 기인하고 있다. 2010/11년도 세계 곡물 생산량은 전 세계적인 이상기후로 전년보다 2% 감소하고, 소비량은 2.4% 증가하여 곡물 기말재고율은 전년대비 3.1%p 하락할 것으로 예상된다. 향후 바이오연료 소비는 지속적으로 증가할 전망이며, 이에 따른 세계 곡물 수요 증가는 불가피해 보인다. 곡물 수급이 전년보다 좋지 않은 상황에서 곡물 선물에 대한 투기가 증가하고, 중국과 인도의 육류 소비 증가에 따른 곡물 소비 증가도 국제곡물 가격 상승의 주된 원인으로 작용하고 잇다. 2010년 하반기 국제곡물 가격을 적용하면, 2011년 상반기 국내 물가 상승은 불가피한 것으로 나타났다. 2011년 상반기 국제곡물 가격을 적용하면, 2011년 상반기 국내 물가 상승은 불가피한 것으로 나타났다. 2011년 상반기 배합사료는 2010년 6월 시세보다 11.5%, 제분 부문은 31.3%, 유지 및 식용유는 6.6%, 제당 부문은 30.0%의 물가 상승요인이 있는 것으로 나타났다. 한편 전분 및 당류는 전년 6월대비 10.9%의 물가 상승요인이 있을 것으로 예상된다. 이와 같이 밀, 옥수수, 대두의 대부분을 수입에 의존하는 우리나라는 국제곡물 가격이 상승할 경우 국내물가 상승이 불가피한 실정이며, 국내 생산을 늘린다 하더라도 수요량을 충족하기에는 한계가 있다. 따라서 국제곡물 수급 및 가격을 상시 모니터링하여 향후 국제곡물 가격을 전망하는 관측시스템 개발을 통해 조기경보를 주고, 이에 따른 매뉴얼을 만들어 대응해야 할 것이다. 한편, 정부 차원에서는 세계 곡물 생산량 감소와 수요 증가로 곡물 공급에 차질이 생길 경우 수입선 다변화 등의 빠른 정책적 대응을 위해 주요 곡물 생산국과의 네트워킹을 강화시킬 필요가 있다.

• Clean Technology
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• v.25 no.1
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• pp.74-80
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• 2019

Thermochemical treatment of sewage sludge is an energy-intensive process due to its high moisture content. To save the energy consumed during the process, the hydrothermal carbonization process for sewage sludge can be used to convert sewage sludge into clean solid fuel without pre-drying. This study is aimed to investigate co-firing characteristics of the hydrothermally carbonated sewage sludge (HCS) to a pulverized coal combustion system. The purpose of the measurement is to measure the pollutants produced during co-firing and combustion efficiency. The combustion system used in this study is a furnace with a down-firing swirl burner of a $80kW_{th}$ thermal input. Two sub-bituminous coals were used as a main fuel, and co-firing ratio of the sewage sludge was varied from 0% to 10% in a thermal basis. Experimental results show that $NO_x$ is 400 ~ 600 ppm, $SO_x$ is 600 ~ 700 ppm, and CO is less than 100 ppm. Experimental results show that stable combustion was achieved for high co-firing ratio of the HCS. Emission of $NO_x$ and $SO_x$ was decreased for higher co-firing ratio in spite of the higher nitrogen contents in the HCS. In addition, it was found that the pollutant emission is affected significantly by composition of the main fuel, regardless of the co-firing ratios.