• 설비공학논문집
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• 제14권5호
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• pp.408-414
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• 2002

The instability of two-phase loop thermosyphons (TLTs) was investigated experimentally. Three orifice type inserts were used to study the effect of change in the pressure drop in the flow channel of the TLT on the flow instability and temperature fluctuation. It is observed that a decrease in the size of the orifice insert from 3.7mm (no insert) to 0.71mm drastically reduced the fluctuation of the temperature, especially at the evaporator section of the TLT With the orifice type insert of 0.71 mm for the TLT, the overall temperature fluctuation was almost completely eliminated, especially at higher power input to the TLT.

• Journal of Biosystems Engineering
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• 제31권3호
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• pp.153-160
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• 2006

This study was performed to evaluate some geometrical characteristics of disc type swirl nozzles and to develop nozzles having improved spraying performance for knapsack sprayers. Considered geometrical characteristics of the nozzles were disc thickness, orifice diameter, swirl chamber diameter and shape of the swirl chamber (nozzle chamber). 3 types of nozzle cores were compared. Main results of this study were as follows. 1. Spraying angle (A) was increased with decreasing disc thickness (x), and with increasing orifice diameter (y) or spraying pressure (z). The equation was as a follow. $$A=3.95\frac{1}{x}+73.50\sqrt{y}+18.97\sqrt{z}-60.16$$ 2. Spraying flow rate (F) was increased with decreasing disc thickness (x), and with increasing orifice diameter (y) or spraying pressure (z). The equation was as a follow. $$F=-89.95x+611.09y+620.49\sqrt{z}-868.20$$ 3. Mean spraying droplet size (V) was decreased with decreasing disc thickness (x), with increasing orifice diameter (y) in low spraying pressure, with decreasing orifice diameter (y) in high spraying pressure, and with increasing spraying pressure (z). $$V=148.77x^4-746.85x^3+1311.76x^2-917.31x$$ 4. The spray pattern was compared using CV values. The CV value of the nozzle core type 1 was 26.7% in spraying pressure $3\;kgf/cm^2$, the CV value of the core type 2 was 23.6% in spraying pressure $2\;kgf/cm^2$, the CV value of the core type 3 was 20.6% in spraying pressure $1\;kgf/cm^2$. 5. Minimum spraying pressure was improved from $1.5\;kgf/cm^2\;to\;1.0\;kgf/cm^2$ by changes of nozzle core shape.

• 대한기계학회논문집B
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• 제24권11호
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• pp.1506-1512
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• 2000

Control of shock may be important in the hydraulic system and necessary to avoid failure and to improve the efficiency of operation. This study addresses the design and use of an orifice to provide the desired control of the hydraulic actuator system. The experimental apparatus is an idealization of an automobile shift system. Control is accomplished by installing three different types of orifices at appropriate locations in the system. Experimental results show that the orifice can be used to obtain the control of shock and control level depends on the orifice size, orifice type, operating pressure and flow rate.

• Journal of Chest Surgery
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• 제21권4호
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• pp.757-760
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• 1988

Double mitral valve orifice is an unusual congenital abnormality, and is rarely of clinical importance. That abnormality not produce hemodynamic deficits, but it has been associated with other congenital heart diseases, especially atrioventricular canal defects, and so it is surgically important condition. After the first report by M.S. Greenfield in 1876, there are only a few reported cases all over the world. We experienced two cases of double mitral valve orifice with atrioventricular canal defect. The small accessory mitral orifice was placed in anterior mitral leaflet as a hole type in both cases. The A-V canal defects are corrected with a one patch technique, but the accessory orifices are left unclosed because there were no mitral regurgitations through the orifice. On the 4th postoperative day, the patients have been performed echocardiography; both had no mitral regurgitation. Both of patients are now being follow-up and we find no specific problems. A small accessory mitral orifice may be left unclosed and rarely produce significant regurgitation, conclusively.

• 한국융합학회논문지
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• 제11권1호
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• pp.195-200
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• 2020

본 연구에서는 쇽업소버 오리피스 유형별 유동해석을 하였다. 좋은 차의 기준에서 중요한 승차감을 위해서는 쇽업소버는 없어서는 안 될 존재이다. 해석 절차로서, 실제 쇽업소버의 실린더가 전진될 때의 속력을 유동 속도로 설정하여 쇽업소버의 모델 A, B, C들에 대한 유동 해석 결과들을 서로 비교하였다. 유동해석을 통해 각 모델의 오리피스 근처에서 유동흐름을 고찰하여 쇽업소버의 성능을 알아보았다. 전반적으로 모델 A가 유속이 가장 빨랐으며 유동변화 또한 가장 컸다. 모델 B가 유속이 가장 느렸으며 오리피스의 개수가 같은 모델 B, C의 유속 형상들은 비슷하였다. 본 연구를 통하여 어느 쇽업소버 오리피스 모델이 실린더 내에서의 유동을 원활히 하여 승차감을 상승시키는지를 알 수 있다. 쇽업소버 오리피스의 유형별 유동해석에 대한 본 해석 결과는 디자인 분야에 융합하여 적용될 수 있다고 보인다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.138-144
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• 2004

Pneumatic damping through a orifice type duct for OWC type wave energy device is studied experimentally. Forced oscillation tests are made to measure chamber pressure and velocity of air flaw through orifice. Pneumatic damping coefficient are deducted from the experimental research, and discussion are made far the influence of frequency, heave amplitude, and orifice size. Finally two formula are proposed for the estimation of non-dimensional pneumatic damping coefficient by regression analysis. The proposed formula proves to be a reliable method far practical application.

• 한국해양공학회지
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• 제18권4호
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• pp.8-14
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• 2004

Pneumatic damping through an orifice-type duct for an OWC-type wave energy device is studied experimentally. Forced oscillation tests are used to measure chamber pressure and velocity of air-flow through an orifice. Pneumatic damping coefficients are deducted from the experimental research, and the influence of frequency, heave amplitude, and orifice size are discussed. Finally, two formulas are proposed for the estimation of non-dimensional pneumatic damping coefficient by regression analysis. The proposed formula proves to be a reliable method for practical application.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.621-626
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• 2000

Reduction in pressure transients may be important in the hydraulic system and necessary to avoid failure and to improve the efficiency of operation. This study addresses the design and use of an orifice to provide the desired control of the hydraulic actuator system. The experimental apparatus is a model of an automobile shift system. Control is accomplished by installing four different diameter ratio of orifices at appropriate locations in the system. Experimental results show that the orifice can be used to obtain the control of shock and the control level depends on the orifice size, orifice type, operating conditions.

• 한국분무공학회지
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• 제6권2호
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• pp.9-15
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• 2001

The internal flow characteristics of a gasoline direct injector have been studied to improve fuel economy and reduce exhaust emissions. Computational Fluid Dynamics (CFD) is used to examine the internal flow of the GDI with the purpose of designing the optimum geometry of the injector. This study tests orifice length, cone angle, swirl angle, orifice diameter and needle lift. The results show that optimum sizes of the orifice length, cone angle, swirl angle, orifice diameter and needle lift are 0.8mm, $140^{\circ},\;120^{\circ},\;80mm\;and\;70{\mu}m$, respectively. The size of the lift does not affect the formation of the air core signficantly near the tip of the needle compared to the ball-type needle. The vena contracta phenomenon near the orifice inlet can be released by smoothing the edge.

• 대한기계학회논문집B
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• 제34권5호
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• pp.457-464
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• 2010

사고로 해양에 유입된 기름을 제거하는 대표적인 방법은 기계적 회수, 화학적인 처리, 수면소각, 미생물에 의한 분해 등이 있으나, 2차오염의 가능성을 방지할 수 있는 기계적인 회수법이 최상으로 생각된다. 기계적 유회수 형태는 벨트, 디스크, Weir, Vortex, 흡입, 드럼, 브러쉬 방식 등이 있다. 저자는 합목적적인 방법으로 회수능력을 개선할 수 있는 실험을 위한 잠수공 모델을 만들었다. 본 스키머의 원리는 외부 액체(물과 기름)를 스키머에 유입시키면, 비중 차에 의해 기름은 뜨고 물은 가라앉는 것이다. 본 스키머는 탱크 바닥의 잠수공으로 물은 빠져나가 스키머 내에 물은 최소로 남고 기름은 모아 회수하는 위어타입의 혁신적인 것이다. 유회수량과 유회수율을 결과로 보였다. 유회수율은 1차 집유탱크의 기름층이 두꺼워지면 증가한다.