• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1365-1367
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• 2000

In electric railway system, potential of rail has been risen, for return-current flows through rail. The magnitude of rising voltage is different to railway feed system, ground admittance of rail and the load current. If rising voltage of rail is large, electric shock can be occurred to passengers and maintenance-worker. In this paper, we estimate the rising voltage of rail in high speed railway system and check the safety to human beings.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.603-605
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• 1998

In recent years, chip delay estimation has had an increasingly important impact on overall design technology. The analysis of the timing behavior of an ASIC should be based not only on the delay characteristics of gates and interconnect circuits but also on the interactions between them. This model plays an important role in our CAD system to analyze the ASIC timing characteristics accurately, together with two-dimensional gate delay table model, AWE algorithm and effective capacitance concept. In this paper, we present an efficient algorithm which accounts for series resistance by computing a reduced-order approximation for the driving-point admittance of an RC-tree and an effective capacitance equation that captures the complete waveform response accurately.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1973-1975
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• 2003

본 논문에선 보정된 차단영역 어드미턴스 인버터 등가회로를 이용하여 밀리미터파 대역의 NRD gap-coupled filter를 설계하였다. 설계된 filter는 3개의 반파장 공진기와 4개의 인버터 (gap)로 구성되어 있다. 인버터에 해당되는 gap (차단영역)의 S 파라미터를 EM 시뮬레이터로 추출해서 어드미턴스 인버터로 구현 하였다 위의 설계과정을 통하여 2% 대역폭, 0.1dB ripple, 38.3GHz를 중심주파수로 갖는 필터를 설계하였고, 보정된 인버터로 설계한 경우가 보정되지 않은 인버터로 설계한 경우보다 정확한 응답특성이 나옴을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.412-414
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• 2004

In this paper, a novel algorithm of underground cable fault location based on the analysis of distributed parameter circuit is proposed. The proposed method makes voltage and current equations about core and sheath, and then establishes a function of the fault distance according to the analysis of fault conditions. Finally gets the solution of this function through Newton-Raphson iteration method. The effectiveness of proposed algorithm has been verified by Matlab program, and the cable parameters such as impedance and admittance are from EMTP simulation.

• KIEE International Transactions on Power Engineering
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• 제3A권1호
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• pp.27-34
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• 2003

In this paper, the power conditioner composed of the stand-alone single-phase squirrel cage rotor type self-excited induction generator (SEIG) driven by prime movers such as a wind turbine and a micro gas turbine (MGT) is presented by using the steady-state circuit analysis based on the two nodal admittance approaches using the per-unit frequency in addition to a new state variable defined by the per-unit slip frequency along with its performance evaluations for the stand-alone energy utilizations. The stande-alone single-phase SEIG operating performances in unregulated voltage control loop are then evaluated on line under the conditions of the speed change transients of the prime mover and the stand-alone electrical passive load power variations with the simple theoretical analysis and the efficient computation processing procedures described in the part I of this paper. In addition, a feasuible PI controlled feedback closed-loop voltage regulation scheme of the stande-alone single-phase SEIG is designed on the basis of the static VAR compensate. (SVC) and discussed in experiment for the promising stand-alone power conditioner. The experimental operating performance results are illustrated and give good agreements with the simulation ones. The simulation and experimental results of the stand-alone single-phase SEIG with the simple SVC controller for its stabilized voltage regulation prove the practical effectiveness of the additional SVC control loop scheme including the PI controller with fast response characteristics and steady-sate performance improvements.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권1호
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• pp.10-15
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• 2003

This paper presents the digital computer performance evaluations of the three-phase self-excited induction generator (SEIG) driven by the variable speed prime mover such as the wind turbine using the nodal admittance approach steady-state frequency domain analysis with the experimental results. The three-phase SEIG setup is implemented for small-scale rural renewable energy utilizations. The experimental performance results give a good agreement with those ones obtained from the digital computer simulation. Furthermore, a feedback closed-loop voltage regulation of the three-phase SEIG as a power conditioner which is driven by a variable speed prime mover employing the static VAR compensator (SVC) circuit composed of the thyristor phase controlled reactor (TCR) and the thyristor switched capacitor(TSC) is designed and considered herein for the wind-turbine driven the power conditioner. To validate the effectiveness of the SVC-based voltage regulator of the terminal voltage of the three-phase SEIG, an inductive load parameter disturbances in stand-alone are applied and characterized in this paper. In the stand-alone power utilization system, the terminal voltage response and thyristor triggering angle response of the TCR are plotted graphically. The simulation and the experimental results prove the effectiveness and validity of the proposed SVC which is controlled by the Pl controller in terms of fast response and high performances of the three-phase SEIG driven directly by the rural renewable energy utilization like a variable-speed prime mover.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권1호
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• pp.1-9
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• 2003

This paper deals with the nodal admittance approach steady-state frequency domain analysis of the three-phase self-excited induction generator (SEIG) driven by the variable speed prime mover as the wind turbine. The steady-state performance analysis of this power conditioner designed for the renewable energy is based on the principle of equating the input mechanical power of the three-phase SEIG to the output mechanical power of the variable speed prime mover mentioned above. Us-ing the approximate frequency domain based equivalent circuit of the three-phase SEIG. The main features of the present algorithm of the steady-state performance analysis of the three-phase SEIG treated here are that the variable speed prime mover characteristics are included in the approximate equivalent circuit of the three-phase SEIG under the condition of the speed changes of the prime mover without complex computations processes. Furthermore, a feedback closed-loop voltage regulation of the three-phase SEIG as a power conditioner which is driven by variable speed prime movers such as the wind turbine(WT) employing the static VAR compensator(SVC) circuit composed of the thyristor phase controlled reactor(TCR) and the thyristor switched capacitor(TSC) controlled by the PI controller is designed and considered for wind-turbine driving power conditioner.

• 대한전자공학회논문지TC
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• 제41권12호
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• pp.93-102
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• 2004

본 논문은 개구면 결합 공진기 급전 마이크로스트립 패치 안테나에 대하여 간결하면서도 정확한 등가회로 모델을 추출하기 위한 일반적인 전자기 이론을 제안하였다. 그리고 등가회로는 이상적인 트랜스, 어드미턴스, 그리고 전송선으로 구성된다. 관련소자들의 값은 복소전력 개념, Fourier 변환, Fourier 급수, 그리고 spectral-domain immittance-approach를 적용하여 계산된다. 본 논문에서는 이 방법을 이용하여 안테나의 입력 임피던스를 구하고, 기존 논문에서 발표된 계산값, 그리고 측정값들과 비교하였다. 기존의 연구 결과와의 정확한 일치는 본 논문이 제안한 등가회로 모델의 간결성과 정확성을 입증해 준다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.226-229
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• 2005

In this study, a step-down piezoelectric transformer was fabricated to utilize as an adapter for charging batteries of mobile electronic appliances. The ceramic part of the transformer is $Pb[(Mn_{1/3}Sb_{2/3})_{0.05}Zr_{0.475}Ti_{0.475}]O_3$ with mechanical quality factor of 1600, electromechanical coupling coefficient 59 %, and piezoelectric constant d33 1300, which can be utilized as a piezoelectric transformer. A simply fabricated disk-typed test pattern of diameter 28 mm and thickness 2 mm was used to characterize resonant frequency, Qm, kp according to the different input/output electrode area. efficiency and power as a function of load resistance was also investigated. The sample APT showed some spurious mode and BPT showed better frequency property. Taking all properties which are admittance, effective electromechanical coupling coefficient and mechanical quality factor most suitable for piezoelectric transformer is BPT which has 12 mm diameter electrode and the condition of 15 Vrms, 30 $\Omega$ made the maximum efficiency of 93.7 % and maximum power is 6W with 50 Vrms.

• 대한전기학회논문지:전력기술부문A
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• 제50권2호
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• pp.90-95
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• 2001

Electric arc furnaces (EAFs) has a process to cause the degradation of the electric power quality such as voltage flicker. In order to adequately understand and analyze the effects on the power system from these loads, obtaining an accurate representation of the characteristics of the loads is crucial. In this paper, a mixed chaotic EAF model to represent the low frequency and high frequency variations of the arc current respectively has been proposed. The Lorenz system may contribute to the low frequency components of arc current and the logistic equation may contribute to the high frequency components, and the proposed mixed model will be a combination of both Lorenz and logistic model. The concept of chaotic parameters, such as chaotic resistance, inductance of admittance has been also proposed for the characterization of arc furnace operation and the highly nonlinear physical processes. The power quality indices are calculated from the simulated waveforms and compared with the actual power quality indices statistics in order to illustrate the model's capabilities.