• Journal of Institute of Control, Robotics and Systems
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• v.18 no.3
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• pp.258-266
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• 2012

This paper describes a biped walking algorithm for a hydraulic humanoid robot on inclined floors. To realize stable and robust biped walking, the walking algorithm was divided into five control strategies. The first is a joint position control strategy. This strategy is for tracking desired joint position trajectories with a gain switching. The second is a multi-model based ZMP (Zero Moment Point) control strategy for dynamic balance. The third is a walking pattern flow control strategy for smooth transition from step to step. The fourth is an ankle compliance control, which increases the dynamic stability at the moment of floor contact. The last is an upright pose control strategy for robust walking on an inclined floor. All strategies are based on simple pendulum models and include practical sensory feedback in order to implement the strategies on a physical robot. Finally, the performance of the control strategies are evaluated and verified through dynamic simulations of a hydraulic humanoid on level and inclined floors.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.147-148
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• 2007

BICC protocol is a relay protocol adaptable to ATM and IP based core networks compared to ISUP protocol to TDM networks. Using BICC protocol, multi-rate bearer traffic such as voice and video can flow in the relay core networks. BICC protocol is standardized as WCDMA circuit switching networks in 3GPP Release 4. Thus KTF is now operating core networks using BICC protocol. In this paper, we describe the background and characteristics of BICC protocol. We also provide the status of KTF WCDMA core networks using BICC. To show the efficiency of BICC protocol an analytical simulation is given in which the results can be expected by intuitive observation.

• 전기의세계
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• v.17 no.4
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• pp.18-27
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• 1968

Analysis of the transient stability of power systems following disturbances involves many sets of non-linear differential equations. This paper attempts to analyze the transient stability of multi-machine power systems by the step by step method, using the electronic digital computer. The critical switching times and phase angles for the main 154KV transmission system in Korea, are given from the swing curves of the probable conditions. It is concluded that the system is, in general, stable if the relay is cut off within 12 cycles after the fault. However the fault of DAEGU-SANGJU branch, accompanying much real power, makes the system unstable when the raly is cut off within 4 cycles after fault or automatic voltage regulators are equipped in this branch.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.11
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• pp.680-686
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• 2004

An integrated inductor using the low temperature cofiring ceramics(LTCC) technology was fabricated. The inductor has Ag circular spiral coil with 16 turns (2-turn x 8-layer) and has a dimension of 11.52mm diameter and 0.71mm thick. For the fabricated inductor, calculation method of inductance was given and it is confirmed that the calculated value is very close to the measured one. Finally as an application of the LTCC integrated inductor to low power electronic circuits, a LTCC buck DC/DC converter with 1.32W output power and 1MHz switching frequency using the inductor fabricated was developed. For the converter the maximum efficiency of about 81% was obtained.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1145-1153
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• 2014

It is well known that line switching operations like reclosing are able to cause transient power oscillations which can stress or damage turbine generators. This paper presents a reclosing scheme to reduce the shaft torsional torques of turbine generators by inserting an additional reactor. A novel method to determine optimal reactor capacity to minimize the torsional torque generated in a turbine generator is also proposed. In this paper, the turbine generator shaft is represented by a multi-mass model to measure torsional torques generated in the shaft between the turbine and the generator. Transmission systems based on actual data from Korea are modeled to verify the proposed scheme using ElectroMagnetic Transient Program (EMTP) software. The simulation results clearly show the effectiveness of the proposed scheme and torsional torque can be minimized by applying the proposed scheme.

• Journal of Power Electronics
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• v.2 no.4
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• pp.312-324
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• 2002

This paper presents a new PWM DC/DC converter with dual output power using single power stage, which has the isolation characteristics between each dual output. The proposed converter topology consists of two switches ($S_B$ and $S_F$) and only single secondary winding. Therefore, the proposed converter has better advantages of not only low cost and small size but also high power density because of using minimum components and devices compared with conventional methods which use multi winding transformers or several converters. The operating principle of the proposed converter topology, which includes the conventional auxiliary ZVT (Zero-Voltage-Transition) circuit to implement soft switching of the main switch, is illustrated in detail and the validity of the proposed converter is verified through several simulated and experimental results.

• Journal of Power Electronics
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• v.12 no.6
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• pp.912-924
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• 2012

In hybrid renewable power systems, the use of a multiple-input dc/dc converter (MIC) leads to simpler circuit and lower cost, when compared to the conventional use of several single-input converters. This paper proposed a novel three-input buck/boost/buck-boost converter, which can be used in applications with various values of input voltage. The energy sources in this converter can deliver power to the load either simultaneously or individually in one switching period. The steady relationship, the power management strategy and the small-signal circuit model of this converter have been derived. With decoupling technology, modeling and regulator design can be obtained under multi-loop control modes. Finally, three generating methods of a multiple-input buck/boost/buck-boost converter is given, and this method can be extended to the other multiple-input dc/dc converters.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.523-525
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• 2001

MPLS(Multi-Protocol Label Switching)망에서 LSP(Label Switched Path)의 수와 레이블 수를 줄이는 것은 망 자원 관리 측면에서 매우 중요하다. 다중점대점(Multipoint-to-Point) LSP[1]는 이러한 요구사항으로 제안되었다. 하나의 다중점대점 LSP는 다수의 망 입구 노드로부터 하나의 망 출구 노드까지의 경로를 나타낸다. 다중 점대점 LSP는 미리 정의된 경로이다. 망 형태 정보가 빈번히 변하는 실제 망을 고려할 대 다중점대점 LSP는 경로가 신속히 재결정될 필요가 있다. 본 논문에서는 망의 트래픽 부하 균형을 위해 Monte-Carlo 시뮬레이션을 이용한 빠른 LSP 결정 방법을 제시한다. 또한 경로 결정시 Greedy 알고리즘을 사용하므로 최적의 다중점대점 LSP 결정에 접근하는 경로를 결정한다.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1084-1086
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• 2003

3-Phase BLDC Motor, which is generally used, has limited usage in high speed, due to pulsation torque occurring commutation and variable speed. To solve this problem, it is necessary to increase invariable, pole number, or the number of slots. Currently, due to rapid growth of semiconductor technology and trend toward smaller and cheaper production of switching device, multi-phase BLDC Motor for high speed, high output power is being actively pursued to produce. In this paper 7-Phase BLDC Motor drive system is designed and Vector modulator is studied.

• Transactions on Electrical and Electronic Materials
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• v.15 no.1
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• pp.12-15
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• 2014

At the moment of transformer energization by the supply voltage, a high current called transient inrush current, which may rise to ten times the transformer full load current, could be drawn by the primary winding. This paper discusses a microcontroller circuit with the intention of controlling and limiting the inrush current for a transformer, by the method of ramping up the supply voltage feeding to the transformer primary. Simulations and the experimental results show a significant reduction of inrush current, when the ramping up voltage is applied to the three-phase transformer load. The inrush current could be almost eliminated if the correct switching step rate is chosen.