• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.198-200
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• 1997

This paper consider a simple Nondestructive Testing(NDT) having eddy currnt effect. We analyzed the two dimension modeling of alternative magnetic field. eddy current with voltage source. And, the current magnitude and phase data obtained from each different frequency five object position is used for learning the neural network. Therefore, we can recognize an object position pattern from new input current magnitude, phase data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.357-359
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• 1995

In this paper, vector control of induction motor drives using space current vector PWM is presented. The scheme gives advantages, besides robustness to inverter arm-shoot, sinusoidal input current and voltage for induction motors. In addition, space vector PWM for CSI produces faster transient response than conventional pattern PWM. Also, a modulation index control is proposed.

• 전력전자학회논문지
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• 제17권4호
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• pp.337-344
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• 2012

A matrix converter is used for converting AC/AC power directly. In order to generate sinusoidal input/output waveform in matrix converter, it uses nine bidirectional switches and PWM modulation. This paper presents an analytical averaged loss model of matrix converter with DDPWM(direct duty ratio PWM) and proposes a new switching method for reducing switching losses. A Mathematical loss models with average magnitude of voltage/current are classed as conduction and switching loss. The proposed switching pattern is improved with existing DDPWM. To prove improved efficiency with proposed DDPWM, this paper compares losses between suggested switching pattern and conventional switching pattern using mathematical and simulation method. Each loss types are influenced by environmental factors such as temperature, switching frequency, output current and modulation method.

• 전자공학회논문지A
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• 제30A권11호
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• pp.40-47
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• 1993

In this paper, a method for analyzing coaxial collinear antenna for base station of mobile communications using the moment method and the transmission line theory is presented. The excited voltages at the junctions between elements are expressed as the matrix with transmission parameters and these voltages are applied to the integral equation for calculating current distribution. Here, the current distributions, input admittances, radiation patterns and gains are calculated. Calculated values of the current distributions and the input admittances show good agreement with measured values. In case of beamtilted collinear antenna, radiation pattern is simialar to measured result except side lobe.

• 정보보호학회논문지
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• 제21권4호
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• pp.47-60
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• 2011

모바일 디바이스(mobile device)를 통한 전자금융거래가 급속하게 증가하면서 이를 대상으로 한 공격시도도 점차 늘어나고 있다. 다양한 보안수단들이 적용되고 있지만, 모바일뱅킹(mobile banking)에 사용되는 디바이스에 원격으로 침입을 한 뒤 공격하는 방법 및 디바이스를 물리적으로 획득하여 전자금융사고를 유발할 수 있는 위험이 여전히 존재한다. 본 논문에서는 모바일 디바이스에서의 전자금융사고 예방 대책으로 개인별 입력패턴을 분석하여 본인에 의한 전자금융거래 시도인지 유무를 판단하여 선제적으로 대응할 수 있는 방안을 제안한다. 화면 터치(touch)를 통해 입력하는 모바일 디바이스의 특성상 터치 시간이나 압력 등의 패턴(pattern)은 개인별로 차이가 있으므로 이를 모니터링(monitoring) 함으로써 정상적인 모바일뱅킹 고객과 공격자를 구분할 수 있다. 본 논문에서 제시된 방안의 효용성을 증명하기 위해 모바일 디바이스에서의 개인별 입력패턴 정보를 실제 수집하여 실험하였고, 실험결과 입력패턴 정보 분석을 통해 전자금융사고를 효과적으로 예방할 수 있음을 확인하였다. 또한, 본 논문에서는 이러한 입력패턴 정보의 모니터링을 이용하여 불법적인 전자금융거래에 실시간으로 대응하는 방안도 제안한다.

• 한국지능시스템학회논문지
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• 제15권2호
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• pp.264-269
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• 2005

Advances in sensors, actuators, and computers and developments In information systems offer unprecedented opportunities to implement highly ambitious automation, control and decision strategies. There are also new challenges and demands for control and automation in modern industrial practices. There is a growing need for an active participation from the information systems in industrial, manufacturing and process industry environments because currently there are many control problems. This paper provides pattern recognition to the monitoring system for solvent manufacturing process and shows performance in real-time response with multiple input signals. Data is teamed by a multilayer feedforward network trained by error-backpropagation. The two kinds of test results show that the trained network has the ability to show the current system status with different input data sets.

• 한국해양공학회지
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• 제18권5호
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• pp.22-28
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• 2004

This study constructed a 3D real-time numerical model that predicts the water quality and movement characteristics of the inner bay, considering the characteristics of the wind-driven current and density current in estuaries, generated by the river discharge from the Hyeong-san river and oceanic water of the Eastern sea. The numerical model successfully calculated the seawater circulation current of Yeong-il Bay, using the input conditions oj the real-time tidal current, river discharge, and weather conditions during March 2001. This study also observed the wind-driven current and density current in estuaries that are effected by the seawater circulation pattern of the inner bay. We investigated and analyzed each impact factor, and its relationship to the water quality of Yeong-il bay.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.1914-1920
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• 2014

In this paper, characteristics of blushless direct current (BLDC) motor including core loss are analyzed considering pulse width modulation (PWM) of inverter. Input voltage of BLDC motor due to PWM is calculated considering duty ratio and carrier frequency of inverter in order to control torque or speed of BLDC motor. For the calculation of core loss, the input current with harmonics due to PWM voltage is calculated by using equivalent circuit model of BLDC motor according to switching pattern and carrier frequency. Next, core loss is analyzed by inputting the currents as a source of BLDC motor for FEM. Characteristics including core loss are compared with ones without PWM waveform according to reference speed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.29-31
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• 1993

This paper presents Neural Network(NN) approach to short-term load forecasting. Input to the NN are past loads and the output is the predicted load for a given day. The NN is used to learn the relationship among past, current and future temperature and loads. Three different cases are presented. Case 1 divides into weekday and weekendday load pattern. Case 2 forcasts 24-hour ahead load. Case 3 searchs for the same load pattern as present load pattern in past load pattern. From result of forecasting, an average absolute percentage errors of case 1 shows 2.0%. That of case 2 shows 2.2, and That of case 3 shows 1.6%.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1203-1205
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• 1998

Fault Detection of power system must be rapid and precise over input signal without relation to any disturbance. But, it is difficult to detect current unbalance, over voltage, and underfrequency for digital relay comparison of fault perfectly. In this paper, we measure each phase current and infer type of fault using fuzzy pattern classification.