• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1053-1064
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• 1999

In this paper, to transmit and receive the differently polarized signals simultaneously with a single antenna system, the dual-frequency microstrip array antenna with dual-polarization is proposed and designed. This antenna operates simultaneously at 14.25 GHz and 12.50 GHz. To extend to two dimensional array, microstrip feed line and coaxial probe through via-hole used.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.4
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• pp.56-64
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• 1997

최근 용접분야에서는 용접성능을 향상시키기 위하여 인버터회로를 용접기에 적용한 인버터 용접기에 관한 연구가 활발히 진행되고 있다,. 그러나 범용의 인버터 용접기의 경우 다이오드 정류기를 사용함에 저차의 전류고조파가 발생하고 시스템 역율을 저하시킨다. 따라서 본 논문에서는 인버터 아크 용접기의 역율개선을 위한 PWM 컨버터에 관하여 연구하여 입력전류의 저차 고조파를 저감하였고 전원전압과 동상으로 전원전류를 제어함에 의한 단위 역율형 인버터 용접기의 특성을 해석하였다. 또한 본 논문에서는 에너지 절약, 용접 특성, 역율, 사용율, 크기 및 부피 등의 관점에서 인버터 아크용접기의 응용연구 및 실험적 분석을 수행하였고 용접기 시스템에서 발생하는 전기적 노이즈를 억제하고 전력용 반도체 소자를 보호할 목적으로 새로운 노이즈 차폐변압기를 채택하였다. 이상의 전체시스템은 싱글칩 마이크로 프로세서를 이용한 디지털 제어기로 구현함으로서 제어기의 유연성과 기능의 다양화를 추구하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.599-602
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• 2006

본 논문에서는 변형된 QMSA에 전기력선이 제한되지 않도록 용량을 장하한 MSA를 제안 하였다. 안테나의 크기는 약 $30mm\times86.6mm\times1.575mm$의 크기를 갖는다. 안테나 특성은 듀얼밴드 설계에서 1.93GHz와 2.03GHz의 두 동작 주파수 동조를 수월하게 하였다. 듀얼밴드 동작을 얻기 위한 기술은 양측 평행 평판과 $\lambda/2$ 방사 폐치를 변화시킴으로서 조정할 수 있다. 또한 1.93GHz 와 2.03GHz의 동작 주파수에 대해 E면과 H면에서 시뮬레이션 된 방사 패턴은 비교 분석되었다. 이동 통신을 위한 설계 제작된 듀얼 밴드 안테나 이득은 약 11.394dBi 이고 이득 변화는 아래와 위 공진 주파수에 대해 1.0dBi 보다 작다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.5
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• pp.411-417
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• 2007

This study has been conducted to investigate pumping characteristics of diffuser/nozzle based piezoelectric micropumps. The micropumps include a piezo disk (an actuator), a chamber and a set of diffuser and nozzle. Flow in the current micropumps is controlled by a set of diffuser and nozzle, not by a nap valve. The diffuser/nozzle based micropumps are more reliable in operation and are easier in manufacturing than the flap valve based micropumps. The flow rates of the piezoelectric micropumps have been closely analyzed with a numerical calculation. It has been found that the positions of the inlet and outlet of the micropump can influence the performance of the diffuser/nozzle based piezoelectric micropumps. This study may provide fundamental understanding for the design and analysis of the piezoelectric micropumps.

• Journal of Sensor Science and Technology
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• v.9 no.3
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• pp.182-189
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• 2000

A micro-vacuum sensor was fabricated for the measurement of the vacuum level in micro-space. The fact that the field emission current was dependent on the environmental vacuum level was employed as an operating principle. The fabricated lateral-type field emitter triode with a cathode, a gate and a anode separated by using the surface micromachining process showed the emission current variation in the range of $1.20{\sim}2.42\;{\mu}A$ for the vacuum range of $10^{-5}{\sim}10^{-8}\;Torr$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.7
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• pp.53-59
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• 2005

In this paper, we proposed the 2-dimensional inspection algorithm for micro-BGA(Ball Grid Array) device using a vision system. The reposed method uses the subpixel algorithm for high precision. The proposed algorithm preferentially extracts the package area of device in the input image. After the extraction of package area, each ball areas are extracted by ball search window method. The parameters for inspection are calculated for the extracted ball area. In the simulation results, we have the average error within 17[${\mu}m$].

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.175-175
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• 2011

인체감지 적외선 센서로 사용되는 마이크로볼로미터 센서 감지재료인 $V_{2-x}W_xO_5$를 증착하고 단위소자를 제작하여 저항 및 센서성능을 측정 조사하였다. 감지재료는 $V_2O_5$에 W을 첨가하여 $V_{2-n}W_nO_5$ 타겟을 제작하였으며 RF sputtering 장비를 이용하여 $V_{1.85}W_{0.15}O_5$ 박막을 증착하였다. 증착온도 $400^{\circ}C$, $Ar/O_2$ 가스비율 50/20, 두께 200nm로 증착된 센서 재료의 특성을 조사한 결과 저항은 약 $20{\sim}70k{\Omega}$이었으며, TCR 값은 -3%/$^{\circ}C$ 이상으로 매우 우수한 박막특성을 얻었다. 볼로미터소자는 $40{\times}40{\sim}140{\times}140um^2$의 셀면적으로 설계하여 전극패턴과 습식식각공정으로 센서 구조체를 제작하였다. 소자의 성능평가는 검출기 측정장비를 이용하여 반응도 및 탐지도 특성을 조사하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.1
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• pp.83-86
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• 2004

A high temperature tolerant microelectronic-based carbon monioxde(CO) gas sensor has been developed. The gas sensing performance has been studied over a wide temperature range$(100-300^\circ{C)}$. The gas sensitivity of the sensor is high, its initial sensing behavior is very fast, and the sensor is reproducible. Pt-SiC and $Pt-SnO_2-SiC$ diodes are fabricated using standard semiconductor processes and their CO gas-sensing behaviors are analyzed as a function of CO gas concentration and temperature by I-V and $\Delta{I-t}$ methods under steady-state and transient conditions. The sensitivity of the device with $Pt-SnO_2$ catalytic gate is higher than that of the Pt gate. The experimental results indicate that $SnO_2$ layer improves the catalytic reaction of the Pt layer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1183-1188
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• 2011

The novel metal position detection method is proposed where conventional techniques, in high temperature, moisture and particle environment, are not able to be applied. It is known that electronic devices, utilizing microwave, ultrasonic or optical technique, are hard to apply for sensing application where temperature is exceeding above 300 degree centigrade. Metal position detection technique, which was consisted with passive elements facing hot sensing surface, utilizing electromagnetic wave was investigated, and the metal detection sensitivity was measured by varying sensor frequency and sensing distance. Measurement result in laboratory test set-up showed position measurement resolution up to 1mm, when distance between two sensing elements were 500mm, and possibility to measure position of hot metal sheet having very high surface temperature.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11B
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• pp.1620-1627
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• 2001

In this paper, a broadband microstrip antenna for PCS and IMT-2000 service is designed. To obtain the broadband characteristics of an antenna, we utilized the multi-layered structure composed of two foam material layers, parasitic element and aperture coupled feeding network. The broadband characteristic is obtained by changing the size of parasitic element and the height of foam materials. In addition to that, the usage of metal layer at the distance of λ/4 from feed-line, back radiation is reduced. The bandwidth of a single element for VSWR less than 1.3 is about 550MHz. The bandwidth of a designed 1$\times$4 array antenna for VSWR less than 1.3 is about 460MHz. The gain of a designed array antenna is about 11.15∼12.15dBi and the front-to-back ratio is about 30dB.