• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2233-2239
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• 2007

The pantograph-catenary system is one of important components for high-speed rail system that are powered electrically. Electrical power is delivered from a catenary structure to the train via a pantograph and thus it is very important to regulate the contact force between catenary and pantograph. Although a lot of research results for active pantograph have been reported, most of them have made an unrealistic assumption that the catenary displacement is constant with respect to the time. In this paper, we present a new pantograph model that regards the catenary displacement as an unknown disturbance input. Moreover, a disturbance observer based controller is proposed to remove the effect of disturbance, i.e., the catenary displacement variation. The computer simulation result shows that the substantial improvement in regulating the contact force can be achieved by the proposed controller.

• Journal of Communications and Networks
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• v.18 no.6
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• pp.873-883
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• 2016

In this paper, we focus on maximizing weighted sum energy efficiency (EE) for a multi-cell multi-user channel. In order to solve this non-convex problem, we first decompose the original problem into a sequence of parallel subproblems which can optimized separately. For each subproblem, a base station employs dirty paper coding to maximize the EE for users within a cell while regulating interference induced to other cells. Since each subproblem can be transformed to a convex multiple-access channel problem, the proposed method provides a closed-form solution for power allocation. Then, based on the derived optimal covariance matrix for each subproblem, a local optimal solution is obtained to maximize the sum EE. Finally, simulation results show that our algorithm based on non-linear precoding achieves about 20 percent performance gains over the conventional linear precoding method.

• The Korean Society of Law and Medicine
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• v.6 no.2
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• pp.291-310
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• 2005

Most of all countries have a governmental system for regulating the certification of nursing. In Korea, certification of advanced practice nurse(APN) is statuary regulation under supervision of government. In this article, the writers discuss the legal characters and effects of certification and regulatory body for certification and suggest the new regulatory system. The advanced practitioner may be recognize "new" health provider in the future. The nursing specialist have right to use title and practice expanded role. It's different things with physicians certification. The regulatory body is important because certification protected the title and empower APN authorize of expanded role. The certification of nursing is closely connected with public interest. The Korea government delegate power of national examination to private institute. To improve utility and publicity of certification system, we suggest that statutory empower the certification authority to public institute which composed with nursing professionals.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.4
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• pp.127-133
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• 1984

In this paper the performance of a variable-phase thyristor motor combined with a phase splitter and a single-phase tapped induction motor is investigated. The phase splitter consists of a bridge type thyristor switching circuit. The regulating power flow of the phase splitter is obtained from the switching phase difference of thyristor switching sequences. The proper switching performance improves the torque-speed-characteristics of the motor and its operation efficiency. We simplify the motor system th using the tapped windng reactances of the motor as the complementary element of the thyristor phase splitter. We discussed the practicality of this motor system through the analysis of simulation result and the voltage and the current wave forms obtained froms obtained from the experiment.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.360-365
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• 2012

Cascaded H-Bridge rectifier (CHBR) is a more attractive solution in traction application for its transformerless structure. Because of the currents of different cells are exactly the same one, it is a challenge job to regulate the voltages of cells with only one current controller. In this paper, a PI-based control scheme is presented to deal with the voltages balance issue in CHBR. To satisfy the demand of rectifier such as unity power factor and regulated output DC voltages, the proposed control scheme consists of two parts. One is for shaping the grid current waveform and regulating the sum of DC-link voltages of all the cells; the other one is for balancing DC-link voltages. The latter is more concerned in this paper and is discussed in detail especially. Simulations and experiments are carried on. The results verified the feasibility and effectiveness of the proposed scheme.

• Journal of Haehwa Medicine
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• v.9 no.1
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• pp.461-467
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• 2000

After analyzing the datas to propose the rightful recognition and research direction for the long used charcoal, the following conclusions are obtained. 1. The 'soot' is pure Korean which has the meaning of 'fresh power' and is translated in English as charcoal which is composition of china and cool meaning good. 2. The main dispositions of the charcoal are 85% of carbon, 10% of water, 4% of minerals and 2% of essential so that the understanding of properties and effects of carbon are essential. 3. It is usually appeared that there are purifying and detoxifying effects of the woods and the room in practical use of charcoal. 4. In everyday life, it removes the odors, regulates the humidity and prevents the decaying. 5. It is often used medically for activating liver fuctions, regulating digestive fuctions and for diseases with inflammations, fever or bleeding. 6. The charcoal is used in medical treatment internally as well as externally. Above conclusions shows that the objective research is needed for clinical use considering the physical and chemical properties in future.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.222-224
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• 2006

Electronic ballast uses various resonant type filters, which perform many important functions such as filtering the high frequency harmonics, shaping the proper lamp current waveform and regulating the lamp power. In this paper, characteristics of resonant type filters are reviewed and the matching problem between inverter and resonant filter are described. Transfer function which is always necessary for the circuit parameter design is derived in case of LCC filter type as an example.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.379-380
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• 2015

최근 전기자동차에 양방향 충전기를 탑재하여 배터리 충전 뿐만 아니라 배터리에 저장된 전기에너지를 전력망으로 재송전하는 V2G 기술과 정전 시 배터리에 축적된 전기에너지를 가정에 공급하는 V2H 기술에 대한 요구가 증대되고 있다. 본 논문에서는 NRSRC(Non-regulating series resoanat converter)기반 정현파 충전 방식과 전해캐패시터를 사용하지 않는 양방향 충전기를 제안한다. 3.3kW 시작품을 통해 제안하는 충전기의 타당성을 검증 하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.593-602
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• 2004

We have developed a digital control rod control system not only to improve its performance but also to improve its reliability and speed of response so that it can replace the old fashioned analog system. However, a new developed digital control system should be tested to prove the validity by using any prototype or mock-up before application. The reliability prediction and the reliability block diagram analysis methods were adopted to verify the reliability of the developed hardware. For the case of software, especially fur a new developed control algorithm it has been tested to prove performances and validation by using a dynamic simulator and mock-up of control rod drive mechanism altogether. Here we want to present some key factors regarding to the new developed digital system with some verification procedures.

• Nuclear Engineering and Technology
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• v.44 no.4
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• pp.369-378
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• 2012

A load-following operation in APR+ nuclear plants is necessary to reduce the need to adjust the boric acid concentration and to efficiently control the control rods for flexible operation. In particular, a disproportion in the axial flux distribution, which is normally caused by a load-following operation in a reactor core, causes xenon oscillation because the absorption cross-section of xenon is extremely large and its effects in a reactor are delayed by the iodine precursor. A model predictive control (MPC) method was used to design an automatic load-following controller for the integrated thermal power level and axial shape index (ASI) control for APR+ nuclear plants. Some tracking controllers employ the current tracking command only. On the other hand, the MPC can achieve better tracking performance because it considers future commands in addition to the current tracking command. The basic concept of the MPC is to solve an optimization problem for generating finite future control inputs at the current time and to implement as the current control input only the first control input among the solutions of the finite time steps. At the next time step, the procedure to solve the optimization problem is then repeated. The support vector regression (SVR) model that is used widely for function approximation problems is used to predict the future outputs based on previous inputs and outputs. In addition, a genetic algorithm is employed to minimize the objective function of a MPC control algorithm with multiple constraints. The power level and ASI are controlled by regulating the control banks and part-strength control banks together with an automatic adjustment of the boric acid concentration. The 3-dimensional MASTER code, which models APR+ nuclear plants, is interfaced to the proposed controller to confirm the performance of the controlling reactor power level and ASI. Numerical simulations showed that the proposed controller exhibits very fast tracking responses.