• 대한기계학회논문집B
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• 제21권6호
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• pp.725-734
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• 1997

The effect of helical intake port geometry on in-cylinder swirl flow characteristics was studied. Two helical intake ports were selected to change swirl ratio, mean flow coefficient with the variation of valve lifts, valve eccentricity ratios and axial distance. The measurements were made by using an impulse swirl meter. The port B modified to increase the swirl ratio( $R_{s}$) had the tendency of the increased non-dimensional rig swirl ( $N_{r}$) distribution in comparison with that of the port A. And the $N_{r}$ distribution was remarkably improved at low valve lifts. The modification of the geometry to increase the swirl ratio ( $R_{s}$) in helical intake port resulted in the decrease of the mean flow coefficient ( $C_{f(mean)}$) regardless of valve eccentricity ratio ( $N_{y}$). And also non-dimensional rig swirl ( $N_{r}$) in the high valve lift affected the calculation of swirl ratio considerably.onsiderably.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2961-2966
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• 2007

When the pressure at the weak spot established at a certain part of a high pressure vessel or piping system exceeds a design pressure, this weak spot is burst, and the pressurized gas emitted through the weak spot will cause a compression wave system. In this connection, in the present study, an experimental study by using a conventional shock tube facility is performed to estimate the effects of the material of diaphragm, curvature radius and thickness of materials on the valve opening time in diaphragm. Pressure sensor having 500kHz in natural frequency is installed at 35mm downstream of the rupture diaphragm to measure the static pressure history of propagating and being accumulated compression wave. 4 kinds of materials are used as diaphragm that is aluminium, copper, stainless steel and zinc. The diaphragm radii of curvature R are ${\infty}$, 120mm and 60, respectively. And the depth for $90^{\circ}$ groove is 0.04mm. It is found that the smaller the tensile strength and elongation of the rupture diaphragm is, the smaller the radius of curvature of the rupture diaphragm is, and for the same conditions the thinner the thickness of the rupture diaphragm is, the shorter the valve opening time becomes. Also, the tensile strength, elongation and the radius of curvature of the rupture diaphragm for the same conditions are smaller, the maximum pressure rise caused by the coalescences of the compression wave is smaller. Finally the pressure ratio is higher, the valve opening time is shortened and gradient of pressure increment is more steepen.

• Journal of Chest Surgery
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• 제40권10호
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• pp.667-673
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• 2007

배경: 심한 대동맥 판막 질환을 가진 환자에서 많은 경우에 승모판막 폐쇄부전을 동반한다. 이런 환자들에서 대동맥 판막 수술 후 남겨지는 승모판막 폐쇄부전의 변화는 수술 등의 치료 과정을 결정하는 데 중요하다. 그러나 대동맥 판막 형태에 따른 대동맥 판막 치환술 후 중등도 이하의 승모판막 폐쇄부전의 변화는 잘 알려져 있지 않다. 본 연구에서는 중등도 이하의 승모판막 폐쇄부전을 동반한 대동맥 판막 협착(Group S)과 폐쇄부전(Group R)을 갖는 두 환자군에서 대동맥 판막 치환술 후 승모판막 폐쇄부전의 변화를 추적 비교해 보았다. 대상 및 방법: 연구 대상은 본 병원에서 1996년 1월에서 2005년 5월까지 대동맥 판막 치환술을 받고 중등도 이하의 승모판막 폐쇄부전을 수술을 하지 않은 환자 43명을 대상으로 하였다. 대상 환자들은 대동맥 판막 협착군(n=29)과 대동맥판막 폐쇄부전군(n=14)으로 나뉘었다. 추적검사 방법은 수술 후 7일, 수술 후 $6{\sim}10$개월 그리고 18개월 이후에 시행한 경흉부 심초음파 결과로 하였으며 평균 추적기간은 38개월이었다. 결과: 평균나이는 60.9세(Group 5=62세, Group R=52.5세)였으며 60% (Group S=55%, Group R=71%)가 남자 환자였다. 수술 전 승모판막 폐쇄부전의 정도는 경도가 29 (67.5%)명이었고 경도와 중등도 사이가 11 (25.5%)명이었으며 중등도가 3 (6.9%)명이었다 Group S에서 승모판 폐쇄부전 정도가 수술 후 수 일 내에 16 (55%)명에서 만 호전을 보였고 수술 후 18개월 후에 시행된 검사에서는 17 (59%)에서 호전을 보였다. 반면에 Group R의 모든 환자에서 조기에 승모판막 폐쇄부전의 호전을 나타냈다. 좌심방 크기감소는 승모판막 폐쇄부전의 호전에 따라 감소하였으나 좌심실 구출률은 두 군에서 의미 있는 차이가 없었다. 결론: 심한 대동맥 판막 질환과 동반된 중등도 이하의 승모판막 폐쇄부전이 있는 환자에서 대동맥 판막치환술 후 승모판막 폐쇄부전의 호전은 대동맥 판막 협착증의 환자보다 대동맥 판막 폐쇄부전 환자에서 보다 조기에 잘 이루어진다.

• 한국기계기술학회지
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• 제13권1호
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• pp.65-71
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• 2011

Steering gear is the part of an automobile that change circular movement of steering wheel to lateral movement of rack to change driving direction. This can be classified with manual and power steering gear. Manual steering gear is operated only with human power while power steering gear use oil pressure support. These days power steering gear is more common to almost of the car. Recently a korean company manufactures a speed sensitive power steering which provide variable steering feel depend on the speed of car. The Broens company of Australia produces and exports the test equipments for the manufacture of power steering valves and assemblies to major vehicle manufactures. Some korean companies imported the test equipments from Australia, thus increasing the cost. The purpose of this study is development of the valve balance test equipment to measure the valve torque of the power steering gear. This study designed and manufactured the valve balance test equipment to take hold of the power steering valve using CAE analysis. In order to evaluate the performance of the developed valve balance test equipment, the R&R tests have been conducted.

• 유공압시스템학회논문집
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• 제6권2호
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• pp.7-13
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• 2009

This study specifies the flow control characteristics of a flow control valve(FCV) in a submerged cargo pumping system through experiments and simulations. In the experiments, the functions of the major components of the FCV in relation to the FCV's flow characteristics are presented clearly. Through the simulations, it is shown that the simulation program suggested in this study can be utilized for the design of the FCV.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.395-396
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• 2011

• 한국자동차공학회논문집
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• 제5권5호
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• pp.157-169
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• 1997

The effects of intake port eccentricity on the characteristics of in-cylinder swirl ratio in a 4-valve diesel engine having the two intake ports; one is a helical intake port and the other is a tangential intake port were investigated by using the ISM(impulse swirl meter) in steady flow test rig. Swirl ratio($R_s$) and mean flow coefficient($C_{f(mean)}$) with valve eccentricity ratio($N_y$) and axial distance(Z/B) were measured. As the results from this experiment, the characteristics of in-cylinder swirl ratio formed by a 4-valve cylinder head were largely affected by intake port eccentricity. There is a difference in the mass flowrate through the two intake ports, and the mass flowrate through the tangential intake port is 19% more than that of the helical intake port. Therefore, we could know that the effects of the mass flowrate ratio through each intake port besides intake port shape should be conidered.

• 대한기계학회논문집B
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• 제21권7호
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• pp.948-961
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• 1997

The effects of intake port eccentricity and a partition between the two intake ports on the incylinder swirl characteristics in a 4 valve diesel engine having the two intake ports, one is a helical intake port and the other is a tangential intake port, were investigated by using the impulse swirl meter(ISM) in a steady flow test rig. Mean flow coefficient ( $C_{f(mean)}$, swirl ratio ( $R_{s}$) and the mass flowrate through the two intake ports with and without intake port partition were measured. The results showed that the characteristics of in-cylinder swirl ratio formed by a 4-valve cylinder head were largely affected by valve eccentricity ratio ( $N_{y}$) and the existence of an intake port partition between the two intake ports. Mean flow coefficient ( $C_{f(mean)}$) increases and swirl ratio ( $R_{s}$) decreases in case of being the partition between the two intake ports. And also the mass flowrate through the tangential intake port is 19.0% and 7.7% more than that of the helical intake port in case of the two intake ports with and without partition respectively.ively.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.433-438
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• 2001

Noise is one of the major environmental problems in human life. To reduce the noise emitted from the control valve it is necessary to develop the measurement method, measurement system, analysis method applicable to the field. In this study IEC and ISO standards were investigated and measurement method for the valve noise was proposed. Noise from the valve was measured in the reverberation room and sound power level was calculated. The sound power level increased as the flow rate and pressure difference increased. The noise characteristics are useful to predict valve noise for given conditions, to compare the performance of different valves and to develope low-noise valves.

• Journal of Biosystems Engineering
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• 제31권1호
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• pp.39-45
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• 2006

Fundamental informations on performance of sets of solenoid valve and nozzle were necessary to develop a target selectable spraying system. The experiments were performed for the sets of solenoid valves and flat spraying nozzles at 3 levels of the operating pressures, and the obtained results are as follows; Rise time of the system pressure to reach up to 90% of the operating pressure after the valve turned was affected by nozzle size and operating pressure. Maximum overshoot of the system pressure was about 170% not affected by the sets of valve and nozzle and operating pressure. The system pressure after its settle down within 5% of the set pressure showed good uniformity in any condition of the experiment as less as 2.3% of its coefficient of variation. Time requirement to lower the system pressure down to 50% after the valve power turned off was affected by valve and nozzle set and operating pressure.