• Journal of the Korean Society for Precision Engineering
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• v.19 no.7
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• pp.36-42
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• 2002

This paper presents two actuators for levitation using repulsions of permanent magnet and two magnetic levitation tables using the actuators. Here, one actuator for levitation consists of one fixed magnet and one moving magnet, and the other actuator consists of two fixed magnets and one moving magnet. The moving part of the magnetic levitation table contains the moving magnets. repulsive forces caused by the permanent magnets are linearized, and then the equation of motion of the moving part of the table is derived. Using the equation of motion, stability conditions of the moving part are deduced. The stability conditions are analyzed for positional relations of the moving magnets and the minimum number of active control required for stable system. As a result, in the each case of magnetic levitation tables, the requirements for stabilization are expressed by the positional relations and the number of the active controls.

• Journal of Korean Society of Water and Wastewater
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• v.7 no.1
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• pp.5-12
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• 1993

The objectives of this paper are to present data to illustrate how an advanced digestion process, two-phase digestion, can provide superior performance in terms of waste stabilization efficiency and net energy recovery. As the result, it is possible to separate enrichment cultures of acidogenic and methanogenic organisms in isolated environments by kinetic control involving manipulation of dilution rates. In single-phase digestion process, HRT and COD loading for effective operation were 14.29 days and 2.33kg $COD/m^3$ day, but two-phase digestion may be conducted efficiently at 7 days of HRT and 5.71kg $COD/m^3$ day of loading. Data from this studies showed that the two-phase process is better than single-phase digestion under all test conditions when compared on the bases of gas yield and production rate, reductions of COD and VS, buffer capacity, and unconverted volatile acids in the effluent.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.206-208
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• 1997

This paper presents a design of self_tuning fuzzy logic controller using Genetic Algorithms for power system stabilization. FPSS(Fuzzy Logic Power System Stabilized is applied to the KERI(Korea Electric Research Int.) power system simulator so that its efficiency can be investigated in real time control. Genetic Algorithms are used to determine fuzzy membership functions. Experiment results show the better performances with FPSS in comparison to no PSS.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.946-947
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• 2015

정지궤도 복합위성용 전력조절장치는 위성의 전력버스에 필요한 전력을 조절하고 배터리의 충전과 방전을 제어하고 관리한다. 전력조절장치의 용량은 1kw로 하고 태양 전지의 어레이는 4개의 패널로 구성되며 S3R(Sequential Switching Shunt Regulator)을 이용하여 조절된 버스전압은 완전조절 50Vdc으로 한다. 변환된 전력은 위성부하에 필요한 전력을 분배하는 PDM(Power Distribution Module)에 공급된다. 남은 전력은 BCR(Battery Charge Regulator)를 통해 배터리에 전력을 충전하고 전력이 부족할 때 BDR(Battery Discharge Regulator)를 통해 방전을 하여 버스전압에 전력을 공급한다.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.457-462
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• 2004

Active magnetic bearings (AMB's) have become practical in many industrial fields and numbers of studies for magnetic bearing systems have been reported. However, AMB systems are open-loop unstable and thus require feedback control for robust stabilization and performance. In this paper, first, a rotation of the rotor around the inertial axis is considered and a rigorous modeling of a magnetic bearing system in which the rotation of the rotor is on its axis of inertia is developed. Next, to stabilize the AMB system a PID controller is used and experimentally analyze its rotational response.

• Journal of Microbiology and Biotechnology
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• v.5 no.4
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• pp.218-223
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• 1995

Veratryl alcohol which has been reported as an inducer for lignin peroxidase showed different effects on the enzyme biosynthesis in Phanerochaete chrysosporium depending on the addition time. Enzyme expression was optimally induced by adding veratryl alcohol when the carbon source began to be depleted. Hydrogen peroxide, to some extent, stimulated production of lignin peroxidase, but beyond a certain concentration, inactivated lignin peroxidase. Tween 80 induced the formation of small pellets, which were resistant to the deactivation by shear stress. Lignin peroxidase production was increased twice compared with that of the control by adopting all the optimal factors in the culture system.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.639-643
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• 2003

We are interested in this paper on the control of an electromechanical system consisting of a doubly-fed induction generator(DFIG), driven by a prime mover that can supply or extract mechanical power, e.g., a flywheel inertia, and an induction motor(IM). The stator of the Induction machine is connected to the stator of the generator whose rotor voltage is regulated by a bidirectional converter. The main interest of this configuration is that it permits a bidirectional power flow between the motor, which may operate in regenerative mode, and the generator We propose a passivity-based controller to regulate the motor mechanical speed. Since this kind of controllers achieve stabilization via energy balancing, regulation of the power flow in the system is naturally incorporated. Simulation results are presented to illustrate the main points of our paper.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.208-210
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• 2008

LRT System Application Project is performed for the purpose of technical advancement and stabilization of K-AGT system from the viewpoint of practical use and commercialization. For those purpose, the performance test and evaluation procedure for K-AGT signaling system are developed, and the scheme of verifying the performance and function of signaling system under multi-train and driverless control environment is being conducted. For the multi-train operation in K-AGT test track, we applied the regenerative energy storage system in addition to the existing electric facilities. This paper present the design, manufacturing, and testing results of regenerative energy storage system.

• Journal of the Korean Professional Engineers Association
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• v.38 no.4
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• pp.7-9
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• 2005

The recent speculation fever in Kangnam and its southern vicnity of Seoul resulted in surging apartment prices. The government is determined to employ more effective anti-speculation policy measures to control the property speculative demand. The Government plans to implement support measures to discourage people from owning multiple homes by reinforcing tax measures. To meet the increasing demand for more large-sized apartments in Seoul, the Government may allow to build more large sized units. By the end of August, 'a comprehensive package tool of real estate policy measures' ,as a real estate controlling guidelines, is scheduled to be presented by the Government. We hope that the package tool will stabilize housing market more effectively and enhance the national economy.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.60-69
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• 2005

In electrostatic suspension system of thin plates like a silicon wafer or an aluminum disk for hard disk applications, the lateral restoring force exerted on a suspended object plays an important role since the lateral motion of the suspended object, owing to the inherently stable restoring forces, can be passively stabilized without any active control of it. This paper reports about the measurement apparatus of the lateral restoring force originating from a relative translation of the suspended object with respect to the electrodes-for-suspension. An approximate calculation of the lateral force in disk-shaped objects, the structure of the measurement apparatus, a measurement method, stabilization condition and the guideline in designing the measurement apparatus are described. Experimental results obtained by using a 3.5-inch aluminum disk as a suspended object are presented as well in order to assess the magnitude of lateral force and stiffness, and also verify the usefulness of the measurement apparatus.