• 한국분무공학회지
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• 제23권2호
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• pp.96-101
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• 2018

The purpose of this study is to investigate the effect of water injection on combustion characteristics of gasoline direct injection (GDI) engine with turbo-charger under low-load operating condition. The test engine used in this study has four-cylinder and 10.2 of compression ratio. In order to study the effect of water injection ratio on combustion characteristics, the water was injected into the intake port from 10% to 50%, based on fuel injection quantity. From the experiment, it revealed that the water injection induced the improvement of fuel economy because of the advance of spark-timing by the reduction of in-cylinder temperature. In addition, the water injection caused the prolong of extension of the ignition delay and slight increase of burn duration.

• 한국분무공학회지
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• 제26권2호
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• pp.96-103
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• 2021

In order to improve the overall efficiency and meet the emission regulations of boiler systems, the heat exchanging methods between inlet air and exhaust gas have been used in boiler systems, named as the waste-heat-recovery condensing boiler. Recently, to further improve the overall efficiency and to reduce the NOx emission simultaneously, the concept of the water injection into the inlet air is introduced. This study suggests the models for the optimized design parameters of water injection for waste-heat-recovery condensing boilers and performs the analysis regarding the water injection amount and droplet sizes for the optimized water injection. At first, the required amount of the water injection was estimated based on the 1^st law of thermodynamics under the assumption of complete evaporation of the injected water. The result showed that the higher the inlet air and exhaust gas temperature into the heat exchanger, the larger the amount of injected water is needed. Then two droplet evaporation models were proposed to analyze the required droplet size of water injection for full evaporation of injected water: one is the evaporation model of droplet in the inlet air and the other is that on the wall of heat exchanger. Based on the results of two models, the maximum allowable droplet sizes of water injection were estimated in various boiler operating conditions with respect to the residence time of the inlet air in the heat exchanger.

• The Journal of Korean Physical Therapy
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• 제15권3호
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• pp.189-201
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• 2003

The purpose of this study was to know the effect of aquatic-exercise on muscle atrophy which induced by steroid injection. The forty-eight Sparague-Dawley adult male rats were assigned to the 4 groups; Group I (distilled water injection), Group II (steroid injection), Group III (distilled water injection with aquatic exercise), Group IV (steroid injection with aquatic exercise). We observed their body weight, muscle relative weight, myofibrillar protein content. The results of this study were as follows; 1. Body weight was decreased rapidly on steroid injection groups in comparison with distilled water injection groups after 2 weeks (p<0.01), but that was almost recovered as before test on steroid injection group with aquatic exercise. 2. The relative weight of gastrocnemius muscles was decreased on steroid injection groups in comparison with distilled water injection groups. however, Decrease of it on steroid injection group with aquatic exercise for steroid injection group was fallen. There was very significant difference after 4 weeks (p<0.01). 3. Myofibrillar protein content of gastrocnemius muscles was decreased on steroid injection groups in comparison with distilled water injection groups. however, Decrease of it on steroid injection group with aquatic exercise for steroid injection group was fallen. There was significant difference after 4 weeks (p<0.05).

• 한국수자원학회논문집
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• 제48권1호
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• pp.23-35
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• 2015

본 연구에서는 3차원 수치모형을 이용하여 염수 대수층 내 담수 주입량에 따른 주입정과 양수정 사이의 담수체의 거동을 수치적으로 분석하였다. 대수층 내에 8개의 주입정이 동심원 상에 등간격으로 배열되어 있으며, 동심원 중심에 한 개의 양수정이 위치해 있다. 주입량이 상대적으로 작은 경우 주입정 주변의 담수체는 인근의 주입정에서의 담수체와 서로 혼합되지 않고 독립적으로 분포한다. 그러나 주입량이 증가함에 따라 담수체의 크기는 점차적으로 증가하며, 주입정과 주입정 사이에 염수와 담수가 혼합되어 있는 영역이 나타난다. 혼합되는 정도는 주입량이 증가함에 따라 증가되며, 이러한 현상은 양수정 주변에서도 동일하게 나타난다. 또한주입량이 증가할수록 양수정 주변 및 내에서의 염수비율이 점차적으로 감소하는 경향을 나타내었다.

• 한국자동차공학회논문집
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• 제23권3호
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• pp.263-270
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• 2015

Using Diesel-Water Emulsion fuel in commercial diesel engine can reduce NOx and soot when it is injected through the injector. Because water in Diesel-Water Emulsion fuel is vaporized ahead of diesel particle and it cause decrease of combustion temperature. Furthermore, research about the possibility of applicating Diesel-Water Emulsion fuels to commercial diesel engine is demanded in order to prove that Diesel-Water Emulsion fuel is able to apply commercial diesel engine without any replacement of equipments. This research analyzed applicable possibility of Diesel-Water Emulsion fuels to commercial diesel engine's fuel injection system refering injection and spray characteristics. In this research, there are 3 experiments, that is injection quantity, spray visualization, and injection rate. Diesel-Water Emulsion fuel has less injection quantities compared to diesel fuel, and spray penetration length is more longer than diesel. Furthermore, emulsion fuels have less dispersed than diesel fuel. In conclusion, comparing with diesel fuel with only spray characteristics, Diesel-Water Emulsion fuel has bad effects about dispersion and vaporization.

• 한국분무공학회지
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• 제8권1호
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• pp.29-36
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• 2003

Spray characteristics on diesel- water emulsion are analyzed in high pressure injection for several variables such as water content, injection pressure. Spray Patterns were visualized under various water content and injection pressures. Spray tip penetration was increased and spray angle decreased in accordance with increasing of water content. But these characteristics were enhanced with increase of injection pressure to high pressure.

• Journal of Advanced Marine Engineering and Technology
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• 제32권3호
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• pp.394-403
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• 2008

The effects of water injection (WI) and urea injection for NOx on a 4-cylinder Direct Injection (DI) diesel engine were investigated experimentally. For water injection, it was installed at the intake pipe and the water quantity was controlled at the intake manifold and Manifold Air Flow (MAF) temperatures while the urea injection was located at the exhaust pipe and the urea quantity was controlled by NOx quantity and MAF. The effects of WI system, urea-SCR system and the combined system were investigated with and without exhaust gas recirculation (EGR). Several experiments were performed to characterize the urea-SCR system, using engine operating points of varying raw NOx emissions. The results of the Stoichiometric Urea Flow (SUF) and NOx map were obtained. In addition, NOx results were illustrated according to the engine speed and load. It is concluded that the NOx reduction effects of the combined system without the EGR were better than those with the EGR-based engine.

• 한국수소및신에너지학회논문집
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• 제25권3호
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• pp.297-304
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• 2014

The purpose of this study is to evaluate the experimental performance characteristics of a water-to-water geothermal heat pump featuring a vapor refrigerant injection for the production of hot water. The performance of geothermal heat pump with a vapor injection was evaluated by comparing with that of a conventional geothermal heat pump without a vapor injection. For heating operation, the geothermal heat pump with a vapor injection is superior in COP and heating capacity. The vapor injection was more effective for supplying hot water while overloading. The vapor injection was effective for the improvement of the cooling capacity. However, the vapor injection was not effective for the increasing of COP according to the increased input of a compressor. The advantage of vapor injection in water-to-water geothermal heat pump become disappeared while cooling operation with lower part loading.

• 한국유체기계학회 논문집
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• 제12권2호
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• pp.46-51
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• 2009

Recently, microturbines have received attention as a small-scale distributed power generator. Since the exhaust gas carries all of the heat release, generating hot water is usual method of heat recovery from microturbine CHP (combined heat and power) systems. The power of microturbines decreases as ambient temperature increases. This study predicted micoturbine power boost by injecting hot water generated by heat recovery. Influence of injecting water at two different locations was examined. Water injection improves power, but efficiency depends much on the injection location. Injecting water at the compressor discharge shows a much higher efficiency than the combustor injection. However, the combustor injection may have as much available cogeneration heat as the dry operation, while the available heat in the compressor discharge injection is much smaller than the dry operation.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권5호
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• pp.39-48
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• 2021

Analysis of the change in water content and distribution was conducted according to the supply of recirculation water to a landfill. An excavation sample analysis showed that the recirculation water injection zone had water content 8.8% point higher than that of the non-injection zone, after 8 months of operation. And due to the influence of recirculation water supply by vertical wells in injection zones, the water content increases along with depth more clearly than non-injection zone. According to an electrical specific-resistivity survey after 13 months of operation, the water content got higher towards the bottom of the landfill. The water transmission coefficient is 8.72×10^-4 cm/sec for injection zones and 3.36×10^-5 cm/sec for the intermediate cover layer; analysis shows that the intermediate cover layer may affect the penetration velocity of water supplied by the horizontal injection tube. For the scientific design and operation of re-injection facilities, it was deemed necessary to follow-up research on the residence time and behavior of re-injection water considering the ratio of recirculation water supply in horizontal and vertical tubes, and pitcher coefficient of intermediate and waste layers.