• 대한기계학회논문집
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• 제16권7호
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• pp.1408-1418
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• 1992

본 연구에서는 여러가지 흡기관 조건 및 밸브타이밍 변화에 대하여, 현재까지 연구에서 확인된 IVC에서 흡기포트압력 값의 체적효율에 대한 영향을 검토하고, 흡기 밸브가 열리는 동안 흡기 포트압력의 어느 부분 또는 지점이 엔진의 체적효율 변화를 설명해 줄 수가 있는지를 실험적으로 규명하고자 하였다.이 목적을 위해 각 흡입조 건에 대한 흡기포트압력 및 엔진 성능값을 측정.분석하여 서로의 연관성을 비교, 검토 하였다.

• 항공우주기술
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• 제3권2호
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• pp.197-207
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• 2004

현재 개발중인 스마트 무인기는 일반적인 헬리콥터와 같이 수직이착륙이 가능할 뿐만 아니라 고정익기와 같이 고속의 비행이 가능함을 목표로 하고 있다. 그러므로 흡기구는 여러 비행조건에서 엔진이 제 효율을 낼 수 있도록 충분한 공기를 흡입하루 수 있어야 함은 물론이고 비행체의 운행속도에 따라서도 그 효율이 어느 이상 저하되지 않도록 설계되어야 한다. 본 논문에서는 고속 비행체에 적합한 pitot 형태와 엔진 특성에 따른 플레넘 챔버를 장착한 흡기구를 설계하였다. 그리고 CFD-ACE를 이용하여 설계된 흡기구의 성능 해석을 수행하였으며 엔진 내부에서의 swirl과 distortion을 조사하고 압력손실에 대해서 연구하였다.

• 대한기계학회논문집B
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• 제26권10호
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• pp.1472-1479
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• 2002

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 marine diesel engines in E3 cycle (propulsion application) and D2 cycle (generation application). Also the effects of important operating parameters in terms of intake air pressure and temperature, and maximum combustion pressure on the specific emissions are described. Emissions measurement and calculation are processed according to IMO Technical Code. The results show that NOx emission level in E3 cycle is higher than that in D2 cycle due to lower engine speed at low load and the maximum combustion pressure by fuel injection timing control and 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.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
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• pp.121-127
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• 2002

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.

• 대한기계학회논문집B
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• 제20권1호
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• pp.275-283
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• 1996

The turbulence in the engine cylinder is generated by intake pressure and inertia effects during intake stroke, and is generated and decreased by piston compression effect during the compression stroke. The classified needed to generate high turbulence flow at vicinity of ignition timing. Therefore, A single-shot Rapid Intake Compression Expansion Machine (RICEM), which is able to realize the intake, compression, expansion or intake-compression stroke under high piston speed respectively, was manufactured and evaluated in order to find methods to generate high turbulence at around spark timing. It was found that the characteristics of RICEM such as reapperance, leakage, piston displacement with crank angle was corresponding to those of real engine and RICEM simulates not only high temperature and high pressure field but also flow patterns of the actual engine by increasing of pressure in intake line.

• 한국항공우주학회지
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• 제34권10호
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• pp.61-70
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• 2006

마하 4 비행 조건에서 작동하는 고성능 램제트와 듀얼모드 스크램제트 엔진의 초음속 공기 흡입구 모델을 설계하였다. 배압, 받음각, 요각 등 비행 변수의 변화에 따른 내부 유동 특성을 파악하기 위하여 규슈대학교의 불어내기식 초음속 풍동을 이용한 실험을 수행하였다. 유동 가시화를 위하여 쉴리렌 기법, 오일 가시화 기법을 이용하였으며, 정량적 성능 분석을 위하여 표면 압력 및 전압력을 측정하였다. 실험의 결과는 전산 유체 해석과 비교하였다. 본 연구는 기본적이지만 찾기 힘든 고 마하수 초음속 공기 흡입구 유동의 실험 결과를 제시한다.

• 동력기계공학회지
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• 제10권3호
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• pp.11-16
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• 2006

The pressure fluctuation in the intake and exhaust pipe of 4 stroke-cycle diesel engine is caused by reciprocating motion of piston for suction of fresh air and exhaust of burned gas. this gas dynamic effect can be utilized for increase the volumetric efficiency. Many empirical studies have been carried out to investigate the effects of intake pulsating flow on the volumetric efficiency. However, when the gas dynamic effects are utilized for the variable speed engine to increase its performance, The speed range in which the maximum volumetric efficiency is limited and there occurs some difficulties in lay-out of intake system because it become too long. During induction process, as waves travel both directions, they are reflected and interacted each other and pressure waves are transmitted through it. Hence, the flow becomes more complex and unsteady flow. These pressure waves act upon intake pulsating flow and affects on the volumetric efficiency. In this paper the effects of pulsating flow of intake and exhaust pipes on volumetric efficiency were examined and evaluated. It was found that volumetric efficiency was affected by pulsating flow of intake and exhaust pipes.

• Journal of Nutrition and Health
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• 제30권1호
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• pp.32-39
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• 1997

This study was desiged to investigate the effects of calcium supplementation on the metabolism of sodium and potassium and blood pressure in seven healthy college women, aged from 19 to 21 years old. For this purpose, metabolic studies were conducted for two weeks. During the first week, the subjects ate experimental diet of which nutrients composition was similar to their usual intake. And during the consecutive second week, they ate the same experimental diet supplemented with 500mg or calcium daily. The results were summarized as follows : 1) Urinary excretion of sodium was significantly increased(p<0.05), but fecal excretion and retention of it was not affected by supplementary intake of calcium. 2) Potassium balance was not changed after additional intake of calcium. 3) Serum sodium and potassium level decreased significantly(p<0.05), but aldosterone and renin levels in serum were not changed by additional intake of calcium. 4) Systolic blood pressure(SBP) was not affected, but diastolic blood pressure (DBP) was significantly decreased (p<0.05) by supplementation of calcium. The above results showed that daily supplementary intake of calcium can be effective to decrease diastolic blood pressure through inducing the change of sodium metabolism in young women eating usual Korean diets.

• Journal of Advanced Marine Engineering and Technology
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• 제26권4호
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• pp.457-463
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• 2002

The closed cycle diesel engine is used in a closed circuit system which has no air breathing. The working fluid as intake mixture are consisted of oxygen, argon and recirculated exhaust gas in order to obtain underwater or underground power sources. In the present study, the high pressure diesel engine which can be operated by the closed cycle system with high intake pressure for increasing the net power rate is designed. It has been carried out to investigate the combustion characteristics of high pressure diesel engine according to the power rate. The maximum cylinder pressure and heat release rate were investigated. Also, major experimental data such as specific fuel consumption rate, oxygen concentrations, fuel conversion efficiency, polytropic exponent, and IMEP were compared with low pressure diesel engine experimental data.

• 한국지역사회생활과학회지
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• 제26권1호
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• pp.167-176
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• 2015

This study compares salt-related dietary patterns according to sodium intake. A survey was conducted with 257 college students(130 male and 127 female students) in the Busan area. Dish Frequency Questionnaire 70(DFQ 70) was used to quantitatively estimate sodium intake. A short dish frequency questionnaire(DFQ 15) was used to screen subjects with high or low- salt intake. The sodium intake of male students based on DFQ 70 was significantly higher than that of female students(p<0.05). Sodium intake has significant negative effects on systolic and diastolic blood pressure(p<0.05). In the high-salt intake(HS) group, classified by DFQ 15, the number of male students was significantly higher than that of female students(p<0.01). The systolic blood pressure of the HS group was significantly higher than that of the low-salt intake(LS) group(p<0.05). Salt-related dietary behavior score and eating habit score for the HS group were significantly higher than those for the LS group(p<0.01). The sodium intake of the HS group based on DFQ 70 was significantly higher than that of the LS group(p<0.01). In these results, college students in Busan area showed high blood pressure and high sodium intake compared to Korean DRIs. The results indicate a need for various education programs to help college students practice a low-sodium diet.