• Design & Manufacturing
• /
• 제14권4호
• /
• pp.52-57
• /
• 2020

In this study attempted to prevent defects due to blow holes among defects of sand casting products. It was intended to reduce the defect rate by reducing the blow hole of the inner surface. Currently, expectations and requirements for the quality level of non-ferrous aluminum casting in the casting industry are increasing. In addition, the shape is complex and the shrinkage precision is required. Among them, the test prototype is expensive to manufacture the mold, and the production time is also long, and the product is manufactured by sand casting. At this time, the highest defect rates are defects caused by shrinkage defects, surface defects, and blow holes.. At this study, the manufacturing time was shortened by using the shape of the fluid movement path in advance. Also, it is possible to reduce defects due to blow holes.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 1995년도 특별강연 및 춘계학술발표 개요집
• /
• pp.74-76
• /
• 1995

• 한국정밀공학회지
• /
• 제13권1호
• /
• pp.69-77
• /
• 1996

To design high-effective profile in screw rotor profile using in screw compressor, we design the symmetric type changing the number of lobes and the non-symmetric type changing the neighbourhood of the top point of lobe. Then, we calculated the performance value of profile according to the scale of these non-symmetric's wrap angle. We had the results as follows. 1. About the non-symmetric case, the larger a wrap angle is the shorter seal line is and the smaller blow hole is, thus we know what the large wrap angle profile is better than the small one. 2. We know what the non-symmetric profile is better than the symmetric profile in the result of the compare of seal line's length, blow hole's area, volume curve. 3. About the non-symmetric case, the deformation of the neighbourhood of lobe's top point of the rotor profile has a large effect upon the increase of performance because the length of seal line became short and the area of blow hole is small.

• Journal of Welding and Joining
• /
• 제19권1호
• /
• pp.21-23
• /
• 2001

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
• /
• pp.585-592
• /
• 2009

The performance of screw compressor depends on lots of design parameters of rotor profile, such as length of seal line, wrap angle, blow hole, suction and discharge port size, number of rotor lobe, etc. The optimum rotor profile makes it possible to increase the compression efficiency with low energy consumption, and to minimize the loss of power. In this research, a new rotor profile design and performance analysis are done by computer simulation. It is expected that the volumetric efficiency is improved because the internal leakage is reduced due to the minimization of blow hole and clearance, and the stiffness of rotors is increased due to the reduction of length to diameter ratio. Also, the specific power consumption will be secured for use ranging from low to high operation speed.

• 한국가시화정보학회지
• /
• 제9권4호
• /
• pp.35-40
• /
• 2011

An experimental investigation of the characteristic of non-premixed lifted flames with nozzle hole-tone of high-frequency has been performed. Before the fuel was supplied to nozzle, the fuel was supplied through a burner cavity which was located under the nozzle. The fuel passed through the excitation cavity under the influence of the high-frequency affects the lifted flame characteristics. The measurements were performed in flow range that occurs lifted flame and blow out. When the high-frequency is generated from burner cavity, the lifted length became shorter, and noise reduced comparing to unexcitation case. Additionally, operating flow range was increased and diameter of flame base became smaller with high-frequency effect. Through this experiments, it's ascertained that the high-frequency excitation can be adopted with effective method for flame stability and noise reduction.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1993년도 춘계학술대회 논문집
• /
• pp.146-150
• /
• 1993

screw압축기는 진동이 적고, 소형이면도 그효율 유지가 용이하다는 특징을 가지고있으며, 왕복압축기와 같은 crank가 없고 원통형 밀폐용기 내에 암,수 로타가 서로 반대 방향으로 맞물려 회전하면서 로타홈과 케이싱 사이에 생기는 공간의 용적이 로타의 회전에 의해서 가스를 연속적으로 흡입, 압축, 배출하는 용적형압축기이다. 본 연구는 screw 압축기의 성능에 큰 영향을 미치는 로타의 치형함수의 기하학적성질 및 제한사항을 서술하였고, 로타의 형상이 특성값에 미치는 영향을 이론적으로 해석 하기 위하여, 임의의 치형을 갖는 로타를 만들고, 이것과 맞물리는 상대로타의 치형을 설계하여 seal line length와 blow hole area을 계산하였다.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 1995년도 제2회 KOSCI Workshop
• /
• pp.105-121
• /
• 1995

The objective of this study is to find out the design data for gas burner with an axal and radial type nozzles. The design parameters are chosen as the stabilizer type, the jet hole size of gas nozzle, the distance between gas nozzle and stabilizer, the size of stabilizer and the hole size of stabilizer, the stabilizer type with or without air swirler, the angle of swirler. For the experimental test combustor sizing ${\phi}1.3m{\times}L4.5m$ is designed and manufactured, in which the set up of power diagram, the exhaust gas analysis, blow-off test, the flame temperature and the direct photography are performed.

• 한국자동차공학회논문집
• /
• 제19권5호
• /
• pp.51-57
• /
• 2011

Parametric studies based on analysis of lubrication system of a four cylinder gasoline engine are illustrated system in this paper. In development process of engine lubrication system, parts of failure cases are related with oil pull over and oil churning phenomenon. The crankcase & head system pressure by oil churning phenomenon are gradual increased. It cause oil pull over phenomenon at engine breather line and oil over-consumption. In order to improve oil reduction and oil pull over phenomenon are also considered in the developing state. For this study, the characteristics of engine lubrication system are measured at various tilting angle and drain hole sizes. In addition, the oil flow & oil quantity are tested by blow by meter and catch jar. Results are presented to stabilize the oil supply system at sever driving condition. The data from present study are available for the engine lubrication system.

• 한국전자파학회논문지
• /
• 제19권2호
• /
• pp.257-262
• /
• 2008

본 논문에서는 열전도도가 우수한 AIN 기판에 $CO_2$ Laser 장비 를 이용하여 Thru-hole과 scribing line을 형성하기 위해 $CO_2$ laser의 파라미터(촛점 거리, 공기량, 레이저 빔 시간, 펄스 개수)를 실험하고, 자체 정렬 마스킹 기법을 이용한 5 um 두께의 Cu 도금으로 AIN 기판에 전송 선로와 나선형 평면 인덕터를 제작하였다. AIN 기판에서의 마이크로스트립 라인의 전송 손실은 10 GHz에서 0.1 dB/mm, 6 nH 나선형 평면 인덕터는 1 GHz에서 56의 품질 계수를 얻었고, 이를 통해 열전도도가 우수한 AIN 기판의 고전력 RF 응용이 가능할 것으로 기대한다.