• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.355-356
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• 2015

This paper proposes a control strategy of total output power ripple cancellation for both of Machine-Side Converter (MSC) and Grid-Side Converter (GSC) in a DFIG under unbalanced grid conditions. The proposed control strategy for the MSC is the zero torque ripple control algorithm with an enhanced LVRT capability. The control algorithm for the MSC exhibits reduced torque pulsation in steady-state unbalanced grid conditions. In addition, this control algorithm also minimizes a peak value of rotor current in transient unbalanced grid conditions. The total output power ripple cancellation control algorithm is adopted in the GSC. The total output power ripple cancellation is achieved by nullifying the oscillating component of the total output active and reactive power at the summing point of stator and rotor of DFIG. The proposed control strategy for the GSC reduces the output power oscillation leading to the improved quality of wind farms output.

• 무역상무연구
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• 제40권
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• pp.33-63
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• 2008

This study introduces the adoption of the logistics industry by the Korean government as a threshold of overcoming economic difficulties. The core contents of the National Logistics Plans (2001-2020) which contain the basic principles of the logistics policies of the Korean government and its aim to be an 'Excellent Nation of Logistics' is introduced. The economic effect of the logistics policies implemented between 2001 and 2005, (the period of the first Medium-term Logistics Plan according to the National Logistics Plans (2001-2020) set up by the Korean government at the end of 2000) is estimated through input-output analysis. The input-output analysis result is as follows: the total output effect is 8,856 billion won of which indirect output effect is 3,982.9 billion won; indirect output effect comes mainly from real estate and business services, non-metal products, metal products, electrical and electronics products, finance and insurance, wholesale and retail, petroleum and coal; the total amount of value-added effect is 3,376 billion won and total import effect is 726 billion won. Employment effect including self-employed and unpaid family supporters with paid laborers is 79,203.7 people of which paid laborers comprise 67,547.7 people.

• 플랜트 저널
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• 제12권4호
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• pp.32-36
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• 2016

본 연구에서는 CGAM 인수성능에 대한 페널티 비용 책정 방법론이 제안되어 있다. CGAM 성능시험결과 전기생산량에서 0.33% 감소, 전기생산효율에서 0.37% 감소, 열생산량에서 0.35% 증가, 열생산효율에서 0.31% 증가하였다. 페널티비용 책정 결과 전기생산량에서 -$22,138, 전기생산효율에서 -$24,348, 열생산량에서 +$11,661, 열생산효율에서 +$10,451로 산정되었다. 위 4 종류의 페널티 산정 계산은 명확하나, 총 페널티 비용은 위 4 종류를 어떻게 조합하는 가에 따라 달라진다. 계산결과 최대 -$46,486부터 -$13,898 범위였다. 따라서 총 페널티 정의에 대한 발주처와 건설사의 협의는 매우 중요하다는 것을 알 수 있다.

• Journal of Power Electronics
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• 제16권4호
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• pp.1407-1414
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• 2016

Unlike existing pulse-width modulation (PWM) techniques, such as sinusoidal PWM and random PWM, the wavelet PWM (WPWM) technique based on a Harr wavelet function can achieve a high fundamental component for the output voltage, low total harmonic distortion, and simple digital implementation. However, the original WPWM method lacks output voltage control. Thus, the practical application of the WPWM technique is limited. This study proposes an improved WPWM technique that can regulate output voltage amplitude with the addition of a parameter. The relationship between the additional parameter and the output voltage amplitude is analyzed in detail. Experimental results verify that the improved WPWM exhibits output voltage control in addition to all the merits of the WPWM technique.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.383-391
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• 1993

In this paper, a new automatic cardiac output control algorithm without any pressure sensors for the motor-driven electromechanical total artificial heart(TAH) was developed using motor current information. In the previous studies, many transducers were utilized to obtain informations of hemodynamic states for the automatic cardiac output control. But. such automatic control with sensors has some problems. To solve these problems, I proposed a new "sensorless" automatic cardiac output control algorithm providing the adequate cardiac output to the time-varying physiological demand without right atrial collapse. In-vitro tests were performed to evaluate the performance of a new algorithm and it satisfied the basic three requirements on the pump output response through the mock circulation tests.

• 전자공학회논문지B
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• 제32B권3호
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• pp.38-47
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• 1995

A new automatic cardiac output control algorithm for the motor-driven electromechanical total artificial heart(TAH) was developed based on the motor current waveform analysis without using any extra transducer. The basic control requirements of artificial heart can be described in terms of three features : preload sensitivity, afterload insensitivity, and balanced ventricular outputs. In the previous studies, many transducers were utilized to obtain informations of hemodynamic states for the automatic cardiac output control, But such automatic control systems with sensors have had reliability problems. We proposed a new sensorless automatic cardiac output control algorithm providing adequate cardiac output to the time-varying physiological demand without causing right atrial collapse, which is one of the critical problem in an active-filling type device. In-vitro tests were performed on a mock circulation system to evaluate the performance of the developed algorithm and the results show that the new algorithm satisfied the basic control requirements on the cardiac output response and the possibility of application of the developed algorithm to in vivo experiments.

• 기술혁신학회지
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• 제4권1호
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• pp.96-109
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• 2001

The aim of this paper is to analyse the impacts on domestic production, value added, employment and import substitution of national technological information activities, using the 1995 Input-Output Tables in Korea. The total output of technological information amounted to 4,167 billion won at current prices. The total domestic output of 2,318 billion won was generated directly and indirectly and the amount of value added totaled 3,773 billion won. 119 thousand new jobs were created and total import substitution amounted to 1,346 billion won. As an increase of 4,167 billion won in technological information sector led to an increase of 7,437 billion won in total socio-economic repercussion effects, the multiplier was 1.8 in 1995.

• 기술혁신학회지
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• 제6권3호
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• pp.328-344
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• 2003

This paper is aimed at analyzing the effect of Information Technology (IT) investment on the output growth and Total Factor Productivity (TFP) of Korean stock industry. Data on 24 stock firms for the eleven years (1991-2001) are used for the analysis. It is identified that there are both direct and indirect impacts of IT investment of the Korean stock industry on output growth. The total effect on output growth is 1.34 percentage point per year, which divided into a direct effect of investment in IT on the output growth is 1.97 and an indirect effect on the TFP is -0.63 percentage points per year. Results show that IT investment cannot contribute to increased stock industry productivity. Therefore, the Korean stock industry has not benefited from increased investment on IT in increasing productivity, implying the so-called productivity paradox has existed during the period.

• Journal of Power Electronics
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• 제9권4호
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• pp.593-603
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• 2009

This paper proposes and describes the design and operational principles of a three-phase three-level nine switch voltage source inverter. The proposed topology consists of three bi-directional switches inserted between the source and the full-bridge power switches of the classical three-phase inverter. As a result, a three-level output voltage waveform and a significant suppression of load harmonics contents are obtained at the inverter output. The harmonics content of the proposed multilevel inverter can be reduced by half compared with two-level inverters. A Fourier analysis of the output waveform is performed and the design is optimized to obtain the minimum total harmonic distortion. The full-bridge power switches of the classical three-phase inverter operate at the line frequency of 50Hz, while the auxiliary circuit switches operate at twice the line frequency. To validate the proposed topology, both simulation and analysis have been performed. In addition, a prototype has been designed, implemented and tested. Selected simulation and experimental results have been provided.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1328-1336
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• 2013

Nowadays multilevel inverters are developing generally due to reduced voltage stress on power switches and low total harmonic distortion (THD) in output voltage. However, for increasing the output voltage levels the number of circuit devices are increased and it results in increasing the cost of converter. In this paper, a novel multilevel inverter is proposed. The suggested topology uses less number of power switches and related gate drive circuits to generate the same level in output voltage with comparison to traditional cascaded multilevel inverter. With the proposed topology all levels in output voltage can be realized. As an illustration, a symmetric 13-level and asymmetric 29-level proposed inverters have been simulated and implemented. The total peak inverse (PIV) and power losses of presented inverter are calculated and compared with conventional cascaded multilevel inverter. The presented analyses show that the power losses in the suggested multilevel inverter are less than the traditional inverters. Presented simulation and experimental results demonstrate the feasibility and applicability of the proposed inverter to obtain the maximum number of levels with less number of switches.