• 한국공작기계학회논문집
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• 제15권2호
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• pp.30-37
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• 2006

The purpose of this study is to visualize the characteristics of ER fluids as preceding step of developing 3 port ER valves. ER fluids are made with silicone oil and 3 weight fraction starch having hydrous particles. The flow visualization of ER fluids flow is obtained by CCD camera with changing the strength of electric field to ER fluids flow. As the strength of the electric field increases, more clusters in flow are made and these clusters are though to be the reasons of the load flow rate being increased and the outlet flow rate being decreased. The ER Valves and load and outlet flow rate check method are considered to be applied to the fluid power control system.

• 동력기계공학회지
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• 제16권6호
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• pp.92-97
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• 2012

In this study, ER fluids were working fluid and yield shear stress of attained dispersive ER fluids made by analyzed to adapt effectively at the practical equipment like three port ER valve. In addition, movement of ER particle was observed by using a microscope the same as the strength of electric field with Bingham characteristic. Basis material was presented to develop 3 port ER-Valve by quantitatively comparing and analyzing entrance, load and outlet flow's differences of 3 port rectangular tubes. This study, after designing and producing the 3port ER-Valve, considered the characteristic of pressure drop, outlet and load flow rate by changing the strength of electric field on ER fluids flowing between electrodes.

• 한국생산제조학회지
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• 제22권2호
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• pp.331-336
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• 2013

The purpose of this study is to visualize the characteristics of ER fluids as preceding step of developing 3 port ER valves. As the strength of the electric field increases, more clusters in flow are made and these clusters are thought to be the reasons of the load flow rate being increased and the outlet flow rate being decreased. The ER Valves and load and outlet flow rate check method are considered to be applied to the fluid power control system. Using the manufactured pressure control valve, a one-link manipulator with FHA in robot system is driven. As a result, it is experimentally confirmed that the pressure control valve using ER fluids is applicable to use in driving actuator. If it applies characteristics of the ER fluids, it will be able to apply in the control system for the ER Valve which occurs from industrial controller(PLC).

• Nuclear Engineering and Technology
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• 제48권6호
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• pp.1349-1359
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• 2016

Alternative control schemes for an Advanced High Temperature Reactor system consisting of a reactor, an intermediate heat exchanger, and a secondary heat exchanger (SHX) are presented in this paper. One scheme is designed to control the cold outlet temperature of the SHX ($T_{co}$) and the hot outlet temperature of the intermediate heat exchanger ($T_{ho2}$) by manipulating the hot-side flow rates of the heat exchangers ($F_h/F_{h2}$) responding to the flow rate and temperature disturbances. The flow rate disturbances typically require a larger manipulation of the flow rates than temperature disturbances. An alternate strategy examines the control of the cold outlet temperature of the SHX ($T_{co}$) only, since this temperature provides the driving force for energy production in the power conversion unit or the process application. The control can be achieved by three options: (1) flow rate manipulation; (2) reactor power manipulation; or (3) a combination of the two. The first option has a quicker response but requires a large flow rate change. The second option is the slowest but does not involve any change in the flow rates of streams. The third option appears preferable as it has an intermediate response time and requires only a minimal flow rate change.

• 한국포장학회지
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• 제28권3호
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• pp.211-215
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• 2022

Air distribution occupies an important position in the smart unit load container design process for agricultural products. Inner air may be uncomfortable because of its temperature, speed, direction, and volume flow rate. It doesn't matter how efficient the ventilation equipment is if the air is not distributed well. The main aim of this study was to design the inlet and outlet fan locations of smart unit load container for agricultural products. A numerical study was performed on the effects of the location of inlet air and outlet air in relation to the container cooling sources on air distribution and thermal comfort. A concept of combining inner container cooling sources with the exhaust outlet was employed in this investigation. Also, in this research, the developed CFD (Computational Fluid Dynamics) models were thoroughly validated. This system was adopted for use in container spaces, where the exhaust outlet was located. In this study, the location of the inlet was derived through CFD for a container with a size of 1,100×1,100×1,700 mm, and it was derived that the inlet was located at the center of the lower part of the container for efficient air flow. It was efficient to position the outlet through the air inlet in the center of the lower part of the container at the top of the same side.

• Journal of Advanced Marine Engineering and Technology
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• 제25권6호
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• pp.1317-1323
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• 2001

The circumstance is giving the blow against fishermen with the incoming-decreasing and the difficulty of crew's supply & demand and management. In addition, the depression of the external situation like the departure of WTO system and the plan of EEZ proclaim is forcing fishery into improving their fishing condition. By this international and domestic circumstance, development of the sea water cooling apparatus for fish hold storage is demanded sincerely. First of all, we Investigated load characteristics which based on development of sea water cooling system and optimum fish hold storage. The experimental results is as follows. In creasing the speed of compressor and mass blew rate of refrigerant, the temperature of NaCl solution is low. And the load characteristics experiment on fish hold storage outlet is as fellows. As time goes by, increasing the mass flow rate of NaCl solution, temperature difference between inlet and outlet is small in a model of fish hold storage. These results provide many useful informations applicable to an actual design of sea water cooling system and optimum fish hold storage.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.433-436
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• 2002

A subwatershed within Juam Lake was monitored to identify hydrologic and water quality characteristics. Rainfall record was collected and flow rate measurement and water quality sampling were conducted periodically at the watershed outlet. Hydrologic response and pollutant load characteristics were analyzed based on observed data.

• 한국기계가공학회지
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• 제4권4호
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• pp.39-47
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• 2005

In this paper, a novel high power micropump using active check valves in place of conventional passive check valves employed at the inlet and outlet ports is presented. It actively controls open/close motion of check valves using piezoelectric actuator for expansion/contraction of pump chamber. A prototype micropump having an effective size of $17mm{\times}8mm{\times}11mm$ is fabricated. Frequency-dependent flow rate characteristics, bi-directional flow characteristics and load characteristics are experimentally investigated using a timing control method for valve closing motion. From the obtained experimental results, it is ascertained that optimal values of the phase shift compared to the voltage to drive pump chamber are $15^{\circ}$ for inlet check valve and $195^{\circ}$ for outlet. Based on the obtained results, a sheet-type active shuttle valve that has a unified valve-body for inlet and outlet check valves is proposed. A micropump with an effective size of $10mm{\times}10mm{\times}10mm$ is fabricated and the basic characteristics are experimentally investigated.

• Tribology and Lubricants
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• 제14권3호
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• pp.39-45
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• 1998

Reynolds equation, which describes behavior of fluid film in journal bearings, basically satisfies mass conservation. But, boundary conditions usually used with this equation, e.g. half Sommerfeld or Reynolds boundary conditions, cannot fulfill this natural law of conservation. In the case of connecting rod bearing, where applied load is dynamic and its magnitude is relatively large, such unrealistic boundary conditions have serious influence on calculation results, especially on lubricant flow rate or power disspation which are important parameters in thermal analysis. In this paper, mass-conserving boundary condition was applied in the finite element analysis of connecting rod bearings. Lubricant flow rate and power dissipation rate were calculated together with journal center locus, minimum film thickness and maxmium film pressure. These computation results were compared with those of the case of Reynolds boundary condition. Balance between inlet and outlet flow rate was well achieved in the case of mass-conserving boundary condition.

• 대한기계학회논문집A
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• 제41권11호
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• pp.1077-1084
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• 2017

기존의 선박용 디젤 엔진에는 항상 일정한 엔진 부하량을 유지하는 캠 구동장치가 적용되고 있었으나, 최근 환경규제로 인하여 엔진 부하량에 따라 실린더 온도를 개별적으로 제어하는 LDCL(Load dependent cylinder liner) JWCS(Jacket water cooling system)가 적용된 전자유압 제어방식이 개발되었다. 이 시스템에서 3-way 밸브는 실린더의 상부와 하부와의 온도 차이를 줄여 저온부식을 방지하는데, 대부분 수입에 의존하고 있으며 토출유량이 낮다. 이에 본 연구에서는 3-way 밸브 내부 형상 관련 설계인자가 성능(토출 유량 및 온도)에 미치는 영향을 파악하여 밸브의 형상 설계를 수행하였으며, 기존 모델과의 성능 비교를 통해 제안된 밸브의 우수성을 검증하였다.