• 대한기계학회논문집B
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• 제25권7호
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• pp.933-943
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• 2001

Using a semi-circled blunt body model, the geometrical effects of injection hole on the turbine blade leading edge film cooling are investigated. The film cooling characteristics of two shaped holes (laterally- and streamwise-diffused holes) and three cylindrical holes with different lateral injection angles, 30°, 45°, 60°, respectively, are compared with those of cylindrical hole with no lateral injection angle experimentally and numerically. Kidney vortices, which decrease the adiabatic film cooling effectiveness, appear on downstream of the cylindrical hole with no lateral injection angle. At downstream of the two shaped holes have better film cooling characteristics than the cylindrical one. Instead of kidney vortices, single vortex appears on downstream of injection holes with lateral injection angle. The adiabatic film cooling effectiveness is symmetrically distributed along the lateral direction downstream of the cylindrical hole with no lateral injection angle. But, at downstream of the cylindrical holes with lateral injection angle, the distribution of adiabatic film cooling effectiveness in the lateral direction shows asymmetric nature and high adiabatic film cooling effectiveness regions are more widely distributed than those of the cylindrical hole with no lateral injection angle. As the blowing ratio increases, also, the effects of hole shapes and injection angles increase.

• 수산해양교육연구
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• 제9권1호
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• pp.83-97
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• 1997

Diesel engine is widely used for ship and industry source of power because of its high thermal efficiency and reliability and durability. However it lead to air pollution due to exhaust gas, and it is important to develop diesel engine of lower air-pollution to decrease the hazardous exhaust gas emissions. As one of the ways, the study for practically using the high pressure of fuel injection and variable injection timing system is being processing. The high pressure injection, which is said to be an effective means for reducing both NOx and particulate emissions, and great improvements in combustion characteristics have been reported by many researchers. In this study, electronic-hydraulic fuel injection system and hydraulic fuel injector system have been applied to the D.I. test engine for high pressure injection and variable injection timing. The injection pressure and injection rate depending upon accumulator pressure were measured with strain gage and Bosch injection rate measuring system before fitting the system into test engine, and analyzed the characteristics of the injection system. The combustion characteristics with this injection system has been analyzed with data concerning heat release rate, pressure rising rate, ignition point, ignition delay and maximum pressure value.

• 한국자동차공학회논문집
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• 제12권5호
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• pp.40-57
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• 2004

The effects of triple (pilot, main and after) injection on combustion and emission characteristics in a HSDI (High-Speed Direct Injection) diesel engine were investigated using a single-cylinder optical diesel engine equipped with a common-rail injection system. The pilot injection affected the spray and combustion evolution of the following main injection. It was found that the pilot injection reduced the ignition delay, which led to lowered NOx (Nitric Oxides) level, and increased IMEP (Indicated Mean Effective Pressure) due to slow combustion pace during an expansion stroke. The after-injection was shown to be effective in reducing PM (Particulate Matter) even when a small amount of fuel was added. The results suggest that a proper combination of individual injection strategy could bring about a good synergetic effect on engine performance and emission.

• 한국자동차공학회논문집
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• 제15권4호
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• pp.76-82
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• 2007

This paper described the effect of the multiple injections on the stability of combustion and emission characteristics in a direct injection diesel engine at various operating conditions. In order to investigate the influence of multiple injections in a diesel engine, the fuel injection timing was varied one main injection and two pilot injections at various conditions. The experimental apparatus consisted of DI diesel engine with four cylinders, EC dynamometer, multi-stage injection control system, and exhaust emissions analyzer. The combustion and emission characteristics were analyzed for the main, pilot-main injection, pilot-pilot-main injection strategies. It is revealed that the combustion pressure was smoothly near the top dead center and the coefficient of variations is reduced due to the effect of pilot injection. Also, $NO_x$ emissions are dramatically decreased with pilot injection because the decrease of rate of heat release. However, the soot is increased at early pilot injection and main injection.

• 한국자동차공학회논문집
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• 제19권3호
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• pp.99-105
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• 2011

This paper described the effect of the multiple injections on the emission characteristics and combustion stability in a common rail diesel engine. In order to investigate the influence of multiple injections in a passenger car diesel engine, the injection strategy was varied with pilot injection, post injection and one main injection at various conditions. Based on the experimental results, the combustion and emissions characteristics were analyzed for the various injection strategies such as main, pilot-main, double-pilot-main, double- pilot-main-post injection strategy. It is revealed that the $NO_X$, HC and CO emissions are reduced by double pilot and post injection at medium load, however, soot emission is increased. Also, in the case of multiple injection, the combustion pressure is increased smoothly near the TDC and the coefficient of variation and fuel consumptions are decreased.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.3007-3012
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• 2008

Multidimensional simulation has been carried out to be clear the role of initial combustion in a marine diesel engines on reduction of NOx and soot emissions by different pilot injection condition. Pilot injection can shorten the ignition delay, thus it reduces the premixed combustion phase. Since most NOx is formed during premixed combustion, pilot injections is one of reliable strategies to reduce the NOx. The formation of NOx consists of that formed by pilot injection and that formed by main injection. The result explains that 25-3-75 among the pilot injection conditions is effective to reduce the NOx, due to optimal combination pilot injection with main injection. The purpose of this study is to explain the characteristics of combustion with pilot injection of the marine diesel engine on reduction of exhaust emissions by examining the combustion process in a cylinder and to explore the formation mechanism of NOx between pilot injection and main injection.

• 한국환경기술학회지
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• 제19권6호
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• pp.570-575
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• 2018

폐수수탁처리업에 반입되는 산업폐수의 원수 성상이 매일 달라짐에 따라 전처리 공정인 응집침전공정의 효율적 운전이 어려운 실정이며, 이로 인해 후처리공정인 증발농축 및 대체 공정인 membrane 공정의 부하원인이 되고 있다. 이에 본 연구에서는 산업폐수의 효율적 처리를 위해 응집제 주입 방법별(단독주입, 동시주입, 순차주입, 역주입) 응집특성을 비교하기 위해 NaOH 주입 전 후 폐수 원수를 채수하여 실험하였다. 응집실험은 Jar-tester를 이용하여 진행하였다. 응집제주입방법별 TDS 제거효율은 순차주입(2.8 %) < 단독주입(3.9 %) < 동시주입(8.1 %) < 역주입(9.6 %) 순으로, TOC 제거효율은 단독주입(84.3 %) < 역주입(86.2 %) < 순차주입(88.6 %) < 동시주입(89.1 %) 순으로, 탁도 제거효율은 단독주입(99.7 %) < 순차주입(99.8 %) ${\fallingdotseq}$ 역주입(99.8 %) < 동시주입(99.9 %) 순으로 각각 나타내어, 이를 종합적으로 고려하여 판단한 결과 순차주입방법(무기응집제${\rightarrow}$고분자응집제)보다 무기응집제 및 고분자응집제를 동시에 주입하는 방법이 더 효율적인 것으로 나타났다.

• 한국자동차공학회논문집
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• 제21권4호
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• pp.89-95
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• 2013

In this work, the evaluation of swirl nozzle injector performance was conducted by investigating effective area ($A_{eff}$), injection mass ($m_{inj}$), injection rate ($Q_{inj}$), and injection delay ($t_{delay}$) under various test conditions. To achieve these, fuel injection analysis system which was composed of fuel supply system, injection system, and control system was installed. At the same time, the swirl nozzle that had 12 orifice hole with $120^{\circ}$ injection angle was used in this work. It was revealed that the difference of injection mass ($m_{inj}$) between base and swirl nozzle injector increased as the injection pressure ($P_{inj}$) and energizing duration ($t_{eng}$) decreased under the same test conditions. The maximum injection rate ($Q_{inj}$) of swirl nozzle injector was higher than base nozzle injector about 2~5%. The injection performance of swirl nozzle was better than base nozzle at low injection pressure ($P_{inj}$) and short energizing duration ($t_{eng}$) conditions.

• 대한간호학회지
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• 제18권3호
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• pp.257-268
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• 1988

The purpose of this study was to compare the effect of the Z-track intramuscular injection technique with the effect of the stand and intramuscular injection technique on the severity of discomfort and leasions at the injection site. The subjects of the study were 20 patients with only early tuber culosis excluding another abnormalities (a akin rash, allergy to topical use of alcohol, jaundice, edema, neurosensory abnormality, coagulation defects, obesity and thin). Data collection was done from Feb. 1 to March 15, 1988 by means of Korean Pain Measurement Tool, Visual Analogue Scale, and Objective measures of injection site lesions. The results of this study were as follows ; 1) Hypothesis 1 ; “The severity of subject discomfort is less following administration of the Z-track intramuscular injection technique than following administra tion injection technique.” was not sopported 2) Hypothesis 2 ; “The degress of severity subject discomfort is less following administration of the Z-track intramuscular injection technique than following administra tion of the standard intramuscular injection technique.” was not supported. 3) Hypothesis 3 ; “The severity of injection site lesions is less following administra tion of the Z-track intramuscular injection technique than following administration of the standard intramuscular injection techniques.” was not supported. 4) The terms that were selected included factor II (mild-moderate pain) of Ratio Scale Measuring Pain using Korean Pain Terms. In conclusion ; it was found that there was not a difference from the severity of subject discomfort between two groups, but the degress of severity of subject discomfort about following administration of the Z-t-rack intramuscular injection was tended to be declined. Therefore further studies suggest that the Z-track intramuscular injection technique can decrease the severity of discomfort in persons receiving frequently intramuscular injections. First of all, it is necessery to be developed an effective tool of discomfort measurement for the intramuscular injection in Korean.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.452-457
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• 2003

As a fundamental study on developing elements with micro shape, micro mold parts machining and experiment of injection molding using it were performed. The ultra precision micro machining system with high functionality was fabricated, and utilized in the machining of micro parts. By using this machining system and micro end-mill tool, a micro circle column structure of high aspect ratio, diameter 60 $\mu\textrm{m}$, height 500 $\mu\textrm{m}$, was fabricated. And a micro lens molds were fabricated by using ball end-mill tool of 300 $\mu\textrm{m}$ diameter and diamond fly-cut tool of 150 $\mu\textrm{m}$ radius. A micro injection molding machine, which is clamping force 1.75 ton, injection capacity 2.8cc, was fabricated for injection molding experiment using micro molds. The injection molding experiment was performed by using the injection molding machine, micro cylinder structures and lens molds. This paper introduces these micro machining system and injection molding machine and demonstrates examples of injection molding using fabricated molds.