• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.2640-2642
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• 2005

Servovalves are widely used in industrial areas in order to control the position of large steam valves which regulate steam flow to prime mover. We must control the position of large steam valves to regulate flow of working fluids in the process. The small pilot valves are used to regulate the large main valves in case that the pressure of control fluids supplied to servovalves is low about $12kg/cm^2$. But, in case that the pressure of control fluids supplied to servovalves is high enough about $110kg/cm^2$, the pilot valves are not needed and servovalves can control directly the large main valves due to its large working forces. Additionally, the basic structures of armature coil should be different according to the types of control system even in the same servovalve. This paper compares and describes some integral types of flow control.

• 전기학회논문지
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• 제59권1호
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• pp.138-143
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• 2010

This paper presents the analysis, the fabrication and the test results of a micro passive gas pressure regulator to keep the outlet pressure costant even for a widely-varying inlet pressure. This device is to regulate the outlet pressure according to the applied reference pressure based on the pressure balancing mechanism of the structure including a membrane and a valve. This regulator consists of four layers; a bulk-micromachined silicon substrate, a sandblasted glass substrate, a PDMS valve seat layer and a glass valve layer. The device size is $10\times13\times1.7 mm3$. The device was fabricated by micromachining. The characteristic of the device was analyzed and tested. The characteristic of the fabricated pressure regulator is similar to that obtained from the analysis. The pressure regulator of this paper is feasible for portable systems and miniature drug delivery systems.

• 로봇학회논문지
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• 제16권2호
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• pp.86-93
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• 2021

This paper proposes a controller to regulate the supply pressure of the hydraulic power unit (HPU) for driving a bipedal robot. We establish flow rate models for charging accumulator, actuating joints and leaking from actuators and spool valves. This determines the pump driving motor speed to satisfy the demanded flow rate for operating the bipedal robot without the energy loss caused by the bypass through a pressure regulating valve. We apply proposed controller to an onboard HPU mounted on top of bipedal robot platform with twelve degrees of freedom. We implement air-walking motion and squat motion which require variable flow rate to the bipedal robot. Through this experiment, the energy efficiency of proposed controller was verified by comparing the electric energy consumed when the controller was applied and when the pump operated at constant speed. We also shows the capability of the HPU's control performance to regulate supply pressure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.638-640
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• 2004

The gas stripper system of a nuclear power plant provides gas-free water to a reactor and a turbine system. The gas tripper unit has two control systems to regulate pressure and level independently. Because the level and the pressure interact as a control disturbance each other, continuous operation of the system is difficult. In this paper, We describe the controllability evaluation of the gas stripper system and the results of the optimally tuned control gains.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1552-1564
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• 2002

Meter-in, meter-out and bleed-off circuits are widely utilized in order to adjust the speed of a hydraulic actuator by using a flow control valve and in order to regulate the pressure of a hydraulic volume by using a simple on-off valve. In these circuits, a relief valve serves either to maintain constant system pressure or to protect the system from over-pressure loading. The relief valve of a bleed-off circuit is the second case frequently undergoing on-off action during operation. It makes the analysis of the pressure control characteristics of the circuit highly difficult. In this paper, steady-state flow rate, pressure, heat loss and efficiency of the three circuits are reexamined and basic experiments far obtaining the characteristics of a pump and relief valve are conducted. Finally, simple empirical first-order dynamic models of decreasing and increasing pressure were separately proposed and verified by comparison with experiment. As the result, the basis for the theoretical analysis of the pressure control characteristics of a bleed-off circuit using a simple on-off valve is established.

• Biomolecules & Therapeutics
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• 제24권1호
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• pp.85-93
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• 2016

We already reported that genetically engineered resveratrol-enriched rice (RR) showed to down-regulate skin melanogenesis. To be developed to increase the bioactivity of RR using calli from plants, RR was adopted for mass production using plant tissue culture technologies. In addition, high-pressure homogenization (HPH) was used to increase the biocompatibility and penetration of the calli from RR into the skin. We aimed to develop anti-melanogenic agents incorporating calli of RR (cRR) and nanoparticles by high-pressure homogenization, examining the synergistic effects on the inhibition of UVB-induced hyperpigmentation. Depigmentation was observed following topical application of micro-cRR, nano-calli of normal rice (cNR), and nano-cRR to ultraviolet B (UVB)-stimulated hyperpigmented guinea pig dorsal skin. Colorimetric analysis, tyrosinase immunostaining, and Fontana-Masson staining for UVB-promoted melanin were performed. Nano-cRR inhibited changes in the melanin color index caused by UVB-promoted hyperpigmentation, and demonstrated stronger anti-melanogenic potential than micro-cRR. In epidermal skin, nano-cRR repressed UVB-promoted melanin granules, thereby suppressing hyperpigmentation. The UVB-enhanced, highly expressed tyrosinase in the basal layer of the epidermis was inhibited by nano-cRR more prominently than by micro-cRR and nano-cNR. The anti-melanogenic potency of nano-cRR also depended on pH and particle size. Nano-cRR shows promising potential to regulate skin pigmentation following UVB exposure.

• KIEE International Transactions on Electrophysics and Applications
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• 제4C권4호
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• pp.155-159
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• 2004

This work reports the theoretical and experimental investigations of capillary bust valves to regulate liquid flow in microchannels. The theoretical analysis uses the Young-Laplace equation and geometrical considerations to predict the pressure at the edge of the valve opening. Numerical simulations are employed to calculate the meniscus shape evolution while the interface is pinned at the valve edge. Microchannels and valves are fabricated using soft lithography. A wafer-rotating system, which can adjust the driving pressure by rotational speed, induces a liquid flow. Experimentally measured valve-bursting pressure agrees with theoretical predictions.

• 한국멀티미디어학회논문지
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• 제18권11호
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• pp.1400-1407
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• 2015

In the paper, we suggest bettered EHMECS(Enhanced Hybrid Multi Electrical Cupping System) to regulate automatically vacuum pressure using many cupping cup at once. We controlled accurately the pressure using S-PI control technique in pump motor to input the air inside cupping cup. S-PI control compared constant velocity, load and velocity variance between existing PI and FLC(Fuzzy Logic Control). The stabilization time of suggested S-PI control improve 20% of existing PI and 8% of FLC. The error constant of normal condition improved 71% of existing PI and 62% of FLC in steady speed and 80% of existing PI and 67% of FLC in load change. Also the error constant about velocity variance improve 45% of PI control. It is prove the suggested S-PI control technique. When use long time vacuum pressure of cupping cup regulated the suggested S-PI control technique, can loosen knotted muscles.

• Journal of Biosystems Engineering
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• 제26권5호
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• pp.409-414
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• 2001

This paper reports a technique for measuring a three-dimensional soil deformation and a simplified method to determine the three-dimensional contact area of agricultural tires in a soil bin. A Pirelli 12.4R28 radial-ply tire was used on soft soil. Effects of dynamic load and inflation pressure were determined using the equipment for measuring soil deformation on the soil surface. Soil deformation measurements were made under three conditions of over-load (59kPa-14.2kN), rated-load (108kPa-11.8kN) and under-load (157kPa-9.3kN) in the combinations of the inflation pressures (kPa) and the tire load (kN). The results from three conditions were shown that the contact area of the over-load increased considerably bigger than those of the rated-load and the under-load. Therefore, to regulate soil deformation, the inflation pressure and the tire load should be set according to the soil conditions.

• 한국항공우주학회지
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• 제37권1호
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• pp.76-81
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• 2009

본 논문에서는 가변 추력 고체추진기관을 모사할 수 있는 상온기체 시험장치를 이용하여 고체추진기관의 연소실 압력을 능동적으로 제어할 수 있는 비선형 압력 제어알고리듬을 제안하였다. 제안된 제어기법은 고체추진기관의 비선형성과 시변성을 고려하여 설계되었으며, 압력 및 온도조건 등에 따른 물리적 변수들의 변화를 적응제어 알고리듬을 통하여 보상하였다. 비선형 압력제어 알고리듬의 효과를 상온기체 모사장치를 이용한 압력제어 실험을 통하여 검증하였으며, 실험결과 일반적인 비례 제어기 및 비례-적분 제어기에 비하여 제안된 제어기법이 더 좋은 압력제어 성능을 보임을 확인하였다.