• 연구논문집
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• 통권29호
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• pp.123-130
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• 1999

Flow divider valve는 한 개의 공급라인에서 두 개 이상의 출력라인으로 유압유를 일정비율로 분배하는 유압제어밸브로서 하중압력이나 공급압력 등에 관계없이 항상 일정비율의 유량분배가 가능해야 한다. 현재 상용제품의 유량분할 정확도는 90~95% 수준이며, 이러한 유량분할오차(Flow dividing error)는 유압시스템에 누적오차로 작용하여 많은 문제점을 야기시키고 있어 보다 고정밀 유량제어가 가능한 Flow divider valve 개발이 요구된다. 본 연구에서는 외력을 고려한 스푸울의 거동을 수치적으로 정확하게 조사하여 Flow divider valve의 동특성을 규명함과 동시에 유량분할 오차를 감소시키는 최적설계방안을 제시하고자 한다. 동특성 해석은 일정한 하중저항을 입력신호로 작용하는 경우에 대해서 제시하였으며, 이때의 고정오리피스와 가변오리피스의 단면적 및 스푸울의 단면적 변화에 따른 동특성의 변화를 조사하였다.

• 한국정밀공학회지
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• 제17권1호
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• pp.198-203
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• 2000

In this paper, a numerical analysis is carried out to show the effect of friction farce on the dynamic characteristics of a flow divider valve. The continuity equations and the equation of motion fur spool are numerically solved. The viscous friction force acting on the spool is considered analyzing the Reynolds equation which governs the viscous flow in the clearance gap between the spool and sleeve. Dynamic characteristics are highly affected by the viscous friction farce whose magnitude is relatively small compare with other fluid forces. Therefore present theoretical formulation and numerical scheme can be used generally in designing and performance evaluation of all the hydraulic spool valve.

• 설비공학논문집
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• 제7권3호
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• pp.528-537
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• 1995

Natural convective flow and heat transfer characteristics in a partially opened enclosure fitted with a horizontal divider are investigated numerically. The enclosure is composed of a lower hot and a upper cold horizontal walls and adiabatic vertical walls. A divider is attached perpendicularly to the vertical insulated wall. The governing equations are solved by using the finite element method with Galerkin method. The computations have been carried out by varying the length of divider, the opening size, and the Rayleigh number based on the temperature difference between two horizontal walls and the enclosure height for air(Pr=0.71). As result, when the opening size is fixed, the intensity of the secondary flow is weaken as the length of divider increases. The maximum heat transfer rate over the upper cold wall occurs at a position bounded on the opening. However, when the length of divider is increased considerably, its maximum occurs at the right wall. The stability and frequency of oscillation are affected by the Rayleigh number and length of divider. The Nusselt number is increased with the increase of the opening size and the increase of Rayleigh number.

• 대한기계학회논문집B
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• 제24권12호
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• pp.1588-1595
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• 2000

Natural convection heat transfer in an enclosure with an opening in the right veritcal wall and a heat source at the bottom surface is investigated using a holographic interferometric technique. The effects of the opening length, divider length attached to the top wall, and heater temperature on the temperature distribution are examined. The opening length as well as the divider length greatly affects the degree of inflow and outflow of air. In the case of small opening length, the opening doesnt affect much the upward warm air flow resulting in the symmetric temperature distribution .The upward flow in hindered by the divider resulting in the decrease of heat transfer from the heater region to the upper region. The longest divider shows the highest temperature in the lower region of enclosure. In the case of large opening length, the inward cold flow moves the upward flow to the left direction. Among the cases of different divider length, the case of H(sub)d=0.25H shows the highest temperature in the lower region of enclosure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.322-327
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• 2000

Natural convection heat transfer in an enclosure with an opening in the right vertical wall and a heat source at the bottom surface is investigated using a holographic interferometric technique. The effects of the opening length, divider length attached to the top wall, and heater temperature on the temperature distribution are examined. The openging length as well as the divider length greatly affects the degree of inflow and outflow of air. With a small opening, the opening doesn't affect much the upward warm air flow resulting in the symmetric temperature distribution. On the other hand, with the increase of the opening length, the inward cold flow moves the upward flow to the left direction. With the increase of the divider length, temperature in the lower region of enclosure becomes higher for the small opening and lower for the large opening.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2016년도 춘계학술발표대회
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• pp.526-528
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• 2016

EPDW는 Event-Process-Data-Work의 약자로 소프트웨어 아키텍처이다. 이 아키텍처는 Event 지향적인 프로그래밍 아키텍처이다. Event 가 발생하면 Process에서 가공하고 Data로 만들어 Work가 처리하는 기본구조를 가지고 있다. 모든 Event는 EventDivider 흐름이 관리되며 Process는 EventDivider에 등록된다. Work는 하나의 기능단위로써 필요한 controller들과 Process들을 가진다. 이를 통해 Event 가공의 코드의 재사용 및 분산방지가 된다. 그리고 Event 흐름의 단순화와 추적의 용이성을 증대해 디버깅에 이점을 가진다.

• 한국토양비료학회지
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• 제41권6호
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• pp.374-378
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• 2008

기존의 전량집수법은 유실된 토양과 물을 전부 채취하기 위하여 시험대상지 하부에 낙차를 두어 일정규모의 집수조를 설치하여야 하고, 유실 토양과 유출 수를 측정한 후에는 집수조 내부의 토양과 물을 전부 제거해야 하므로 집수조의 설치 및 관리에 많은 노력과 비용이 소요된다. 이러한 집수구 설치 및 관리상의 문제점을 개선하기 위하여 토양보전시험연구를 위하여 장소선정이 용이하고, 시험포장에서 배출되는 토양유실 및 유출수의 측정과 시료채취 작업이 간편한 회전분할집수기를 제작하여 기존의 표준방법과 비교하였다. 농경지에서 유실되는 토양과 물을 일정 비율로 채취하기 위하여 집수기의 원형판을 8부분으로 분할하여 각 날개에 일정량의 물이나 토양이 채워지면 무게 중심이 아래로 이동하는 방법으로 소량의 물이나 토양에 의해 자체 회전하면서 시료 중 일부만 채취하도록 하였고, 집수기 자체의 각도를 기울여 각각의 날개에 채워진 유출수와 유실토양은 원형판이 가장 낮은곳에서 회전할 때 비워지도록 하였다. 회전분할집수기의 정밀도를 비교하기 위하여 실내실험으로 유수량을 $1{\sim}10L\;min^{-1}$로 조절하여 유출수량과 회전분할집수기의 채취량을 비교한 결과 고도의 직선적인 정의상관 ($r=0.997^{***}$)을 보였으며, 야외 시험포장에서 회전분할집수기 시제품을 설치하여 측정한 결과 집수비율은 토양 유실량 및 물 유출량이 많을수록 정밀도가 높았다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권1호
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• pp.107-116
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• 2012

In this paper, the trade-off related to bandwidth of high-speed common-mode logic frequency divider is analyzed in detail. A method to optimize the operating frequency, band-width as well as power consumption is proposed. This method is based on bipolar device characteristics, whereby a negative resistance model can be used to estimate the optimal normalized upper frequency and lower frequency of frequency dividers under different conditions, which is conventionally ignored in literatures. This method provides a simple but efficient procedure in designing high performance frequency dividers for different applications. To verify the proposed method, a static divide-by-2 at millimeter wave ranges is implemented in 180 nm SiGe technology. Measurement results of the divider demonstrate significant improvement in the figure of merit as compared with literatures.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.379-384
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• 2003

Coal-burning utilities are facing a major NOx control compliance challenge due to the heavy emission regulation. In response to this challenge, some applicative technologies to effectively reduce NOx are developed and applied in the pulverized coal power plants. One of these is low NOx burner(LNB) equipped with multi-staged air register. In this study, NOx emission rate and flame shapes are investigated with secondary and tertiary air flow conditions in air staged coal burner, and the optimal windows of flow conditions to minimize NOx emission rate are found out. The test conditions treated in this study are the flow rate, swirl direction and intensity and throat injection velocity of secondary and tertiary air.

• Korea-Australia Rheology Journal
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• 제18권2호
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• pp.51-65
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• 2006

Of concern in the present theoretical investigation is the study of blood flow and convection-dominated diffusion processes in a model bifurcated artery under stenotic conditions. The geometry of the bifurcated arterial segment having constrictions in both the parent and its daughter arterial lumen frequently appearing in the diseased arteries causing malfunction of the cardiovascular system, is constructed mathematically with the introduction of suitable curvatures at the lateral junction and the flow divider. The streaming blood contained in the bifurcated artery is treated to be Newtonian. The flow dynamical analysis applies the two-dimensional unsteady incompressible nonlinear Wavier-Stokes equations for Newtonian fluid while the mass transport phenomenon is governed by the convection diffusion equation. The motion of the arterial wall and its effect on local fluid mechanics is, however, not ruled out from the present model. The main objective of this study is to demonstrate the effects of constricted flow characteristics and the wall motion on the wall shear stress, the concentration profile and on the mass transfer. The ultimate numerical solutions of the coupled flow and diffusion processes following a radial coordinate transformation are based on an appropriate finite difference technique which attain appreciable stability in both the flow phenomena and the convection-dominated diffusion processes.