• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.361-365
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• 2002

Advancements in silicon phase control (SCR) technologies provide an arc welding power supply that has the capability to allow the alteration of the Alternating Current (AC) welding output. These technologies provide a square wave output involving sixteen frequency selections and multiple balance selections. While an AC out put is known to minimize magnetic disturbances associate with Direct Current (DC), the potentials of a non-sinusoidal waveform have not been explored. The focus of the paper is to determine the effects that the frequency and balance of an AC wave form output will have upon a high speed Submerge Arc (SAW) application. The test matrix of the project includes welding .250" steel plate. Joint type is square groove with a travel speed of 65 IPM. Each of the weld parameters was held constant, only the frequency and/or balance were altered between welds. Each frequency/balance combination involved three-gap spacing. Upon completion of the welds the bead profiles were measured and recorded. A relationships/trends were observed with various frequency and balance values. Optimum frequency and balance values were found for the .250" square groove application which permit consistent weld sizing, ease of slag removal, and minimal plate distortion.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.734-738
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• 1996

An adaptive output feedback controller is designed for tracking control of an n-link robot manipulator with unknown load. High-gain observers with same structure as error dynamic systems are used to estimate joint velocities. The parameter adaptation is achieved by the smoothed projection algorithm. The control inputs are saturated outside a domain of interest. Simulation results on a 2-link manipulator illustrate that when the speed of the high-gain observer is sufficiently high, the proposed controller recovers the performance under state feedback control.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2769-2772
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• 2003

This paper presents results of the development of the Turbo-generator system with structure which is HSG(High Speed Generator) installed to high speed gas-turbine engine directly. Turbo-generator with high speed motor-generator directly has many advantages aspects of weight, size, lubrication system and complexity of the system compared of conventional turbo-generator system with gear-box. But because of direct high speed operation of the high speed generator, we have to need stable high speed motor driving algorithm for perfect engine ignition when gas turbine starting. Also we have to need design of the PCU(Power Conditioning Unit) for converting high speed AC output power to conventional AC power or needed DC power.

• 한국컴퓨터정보학회논문지
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• 제12권1호
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• pp.155-160
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• 2007

고속 데이터 전송에 적합한 Multi-Code CDMA 시스템은 출력이 Multi-Level이 됨으로써 출력신호의 복잡성과 출력단에 선형적인 증폭기를 사용하므로 고가, 고복잡성 등의 단점을 가진다. 이러한 단점을 보완하고자 기존 CDMA 기술에 기반을 둔 Binary CDMA 기술이 제안되었다. Binary CDMA 시스템에서 고속 데이터 연산 시 병목현상이 발생되는 코릴레이터는 동기획득시 매우 중요한 파라미터이다. 기존의 코릴레이터는 전력소모가 작다는 장점이 있지만 코릴레이션의 값을 얻기 위해 여러단의 가산을 거쳐야 하므로 연산량이 많아 처리 속도가 낮은 단점을 가지고 있다. 그러므로 본 논문은 Binary CDMA 시스템에서 고속의 데이터를 처리할 수 있으며 데이터 량이 증가하더라도 칩 면적이 독립적이며 전력소모가 일정한 구조를 가지는 코릴레이터를 제안하였다.

• 한국전자통신학회논문지
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• 제3권3호
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• pp.177-182
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• 2008

고속 전송에 적합한 MC-CDMA시스템은 출력이 Multi-Level로 출력됨으로 인하여 출력신호의 복잡성과 출력단의 선형적인 증폭기 사용으로 인한 고가, 고복잡성 등의 단점을 가진다. 이러한 단점을 보완하고자 제안된 기술이 Binary CDMA 기술이다. Binary CDMA 시스템에서 가장 중요한 파라미터는 고속 데이터 연산 시 병목현상이 발생되는 코릴레이터이다. 기존의 코릴레이터는 전력소모가 작다는 장점이 있지만 코릴레이션의 값을 얻기 위해 여러 단의 가산을 거쳐야 하므로 연산량이 많아 처리 속도가 낮아지는 단점을 가지고 있다. 그러므로 본 논문에서는 Binary CDMA 시스템에서 고속의 데이터를 처리함과 동시에 데이터 량이 증가하더라도 칩 면적이 독립적이며 전력소모가 일정한 구조를 가지는 Binary CDMA 시스템 PBS 코릴레이터를 제안하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2552-2556
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• 2005

In general, the forklift driven by DC motor drive system is used in the industrial field. Classically, the DC motor is controlled by current control using proportion control method, by output torque following the load on the plane like a manual operation. But in the industrial field, the forklift is demanded the robust drive mode. Some cases of the mode, there aretrouble in torque control following slope capacity. The control is sensitive concerning about slope angle and output speed, various control method is studied for stability of speed control. In this paper, I apply current control for the self-tuning using the fuzzy controller to obtain robust, stable speed control and use stable, high efficiency control using DSP as main controller for high speed processor, embody dynamic characteristic of control compared the PI controller to the fuzzy controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.576-578
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• 1989

This paper describes a new pwm scheme of variable speed control for induction motor. The proposed scheme have the programmed pwm switching pattern which have the doninant harmonic elimination over the wide range of output speed in induction motor. Experimental results of proposed scheme hare high quality output current, voltage and torque than that of conventional pwm scheme. Therefore proposed scheme have the smooth operation and suitable for variable speed control in induction motor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.105-110
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• 2008

This Paper proposes Dual-PI controller for high performance control of IPMSM drive. Input of traditional PI control used speed error, but Dual-PI controller used two input speed error, current error and output is output is f-axis current. Dual-PI controller is Possible both speed control and current control because it used speed error and current error Therefore, dual-PI controller can is reduced current ripple. This paper is made analysis performance of algorithm and proposes result.

• Journal of the Korean Physical Society
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• 제73권12호
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• pp.1889-1894
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• 2018

An innovative small-scale piezoelectric energy harvester has been proposed to gather wind energy. A conventional horizontal-axis wind power generation has a low generating efficiency at low wind speed. To overcome this weakness, we designed a piezoelectric windmill optimized at low-speed wind. A piezoelectric device having high energy conversion efficiency is used in a small windmill. The maximum output power of the windmill was about 3.14 mW when wind speed was 1.94 m/s. Finally, the output power and the efficiency of the system were compared with a conventional wind power system. This work will be beneficial for the piezoelectric energy harvesting technology to be applied to the real world such as wireless sensor networks (WSN).

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권3호
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• pp.81-89
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• 2002

The sensorless AC motor drive is a popular topic of study due to the cost and reliability of speed and position sensors. Most sensorless algorithms are based on the mathematical modeling of motors including electrical variables such as phase current and voltage. Therefore, the accuracy of such variables largely affects the performance of the sensorless AC motor drive. However, the output voltage of the SVPWM-VSI, which is widely used in sensorless AC motor drives, has considerable errors. In particular, the SVPWM-VSI is error-prone in the low speed range because the constant DC link voltage causes poor resolution in a low output voltage command and the output voltage is distorted due to dead time and voltage drop. This paper investigates a novel high-performance strategy for overcoming these problems in a sensorless ac motor drive. In this paper, a variation of the DC link voltage and a direct compensation for dead time and voltage drop are proposed. The variable DC link voltage leads to an improved resolution of the inverter output voltage, especially in the motor's low speed range. The direct compensation for dead time and voltage drop directly calculates the duration of the switching voltage vector without the modification of the reference voltage and needs no additional circuits. In addition, the proposed strategy reduces a current ripple, which deteriorates the accuracy of a monitored current and causes torque ripple and additional loss. Simulation and experimentation have been performed to verify the proposed strategy.