• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.191-194
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• 2000

In this study, experimental verification of performance of flat speaker has been conducted. The piezofilm (PVDF) actuator has been designed to prevent the distortion of sound and make the frequency response of radiated sound flat. The electrode pattern of piezofilm actuator is optimized to satisfy the design objective. The formulation of design method is based on the coupled finite element and boundary element method and electrode pattern is optimized by genetic algorithm. The flat speaker with optimized piezofilm actuator has been manufactured. The sound pressure level at the distance of 50cm is measured using microphone and compared with the result of numerical simulation.

• 센서학회지
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• 제14권2호
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• pp.85-90
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• 2005

In this study, we have fabricated a three branches vertical Hall sensor for detecting three phases rotation informations of miniaturized brushless motor. The sensor gives three position signals phase shifted by $120^{\circ}$, corresponding to the motor driving signals. The branch has one Hall output and one input each other. The central part acts as common driving input. Sensor has branch width of $150{\mu}m$ and distance from central electrode to Hall electrode of $100{\mu}m$. The sensitivity of sensor is 250 V/$A{\cdot}T$ at magnetic field of 0.1 T. It has also showed three sine waves of Hall voltages with $120^{\circ}$ phase over a $360^{\circ}$ rotation. A packaged sensing part are $2{\times}2mm^{2}$ and has been successfully tested on a motor rotation at a speed up to 60,000 rpm.

• 방사성폐기물학회지
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• 제15권4호
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• pp.321-332
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• 2017

전극 구성에 따른 고효율 전해정련공정의 일반적인 모델을 구축하기 위하여, 상미분방정식 인터페이스를 갖는 COMSOL Multiphysics V5.3 전착 모듈을 사용하여 수치해석을 실시하였다. 구축된 모델은 한국원자력연구원에서 제작한 실험실 규모 (1kg 우라늄/day 규모) 다중배열전극 전해정련장치를 사용해 전극 간 거리, 전극 배열을 변수로 하여 실시한 실험의 전류밀도-전위 곡선과 비교하였다. 공정온도는 $500^{\circ}C$이다. 용융염은 3wt% $UCl_3$가 포함된 LiCl-KCl 공융염을 사용하였다. 검증된 모델을 이용하여 전류밀도-셀전위 곡선을 계산한 결과 전극 간 거리가 가까울수록, 전극 배열은 양극/음극 면적비가 증가할수록 셀 전위가 낮아져 전해정련장치의 우라늄 처리효율을 향상시킬 수 있다는 것을 확인하였다. 이러한 접근은 고출력 사용후핵연료 전해정련기의 안전설계를 위한 데이터베이스 구축에 유용할 것이다.

• Journal of Welding and Joining
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• 제14권5호
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• pp.87-94
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• 1996

It has been well known in GMA welding process that wire feeding speed (WFS) or deposition rate increases linealy with the increase of wire extension. In this investigation, however, such an well-known relationship was .reconsidered in terms of contact-tube to work distance (CTWD) instead of wire extension. To verify the proposed relationship between WFS and CTWD, bead-on-plate welding was performed with various CTWDs in the range of 15∼35mm under the condition of near-constant voltage and current As expected, the test results showed an excellent linear relation between WFS and CTWD. Furthermore, the value of the slope turned out to be quite similar to those of previous investigators obtained either theoretically or experimentally through the Precise measurement of electrode extension. Present result also demonstred that the increase of CTWD could be very practical measure for increaring deposition rate without any increase of heat input Depending on the tip recess the practical maximum of CTWD was appeared to be limited somewhere in 25∼30mm mainly due to the entrappment of porocity.

• 전기학회논문지
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• 제59권1호
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• pp.108-112
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• 2010

Design of experiment (DOE) method is employed for a systematic and highly efficient optimization of Ga-doped ZnO thin films synthesized by pulsed laser deposition (PLD) process. We sequentially adopted fractional-factorial design (FD) and central composite design (CCD) of the DOE methods. In fractional-FD stage, significant factors to make conductive electrode are found to target-substrate (T-S) distance and oxygen partial pressure. Moreover, correlation among the process factors is elucidated using surface profile modeling. Electrical properties of the GZO films grown on a glass substrate had been optimized to find that the lowest electrical resistivity of about $1.8'10^{-4}Wcm$ which was acquired with the T-S distance and the oxygen pressure of 4 cm and 7 mTorr, respectively. During the DOE-fueled optimization process, the transparency of the GZO films is ensured higher than 85 %.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1489-1491
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• 2004

PD in air is accompanied by light, sound and electromagnetic wave. Light and sound can be prevented from blocking between PD sources and sensor but electromagnetic wave can be transferred to long distance without any interference an captured by antenna. This paper investigated the wideband antenna is appropriate for sensing Partial discharge in air. PD was generated from simulated PD source which consist of needle and flat electrode with small gap. Signals obtained from wideband antenna were diminished in both time and frequence region with the distance between PD source and antenna.

• 한국안전학회지
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• 제15권1호
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• pp.121-125
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• 2000

This study was executed by dust explosion experiment of terephthalic acid which was widely used for various purposes of food packing material and film etc. and the demand was rapidly increasing. The particle size and concentration of dust affected the minimum ignition energy largely and the lean concentration and the minimum ignition energy in the range of this study were obtained 50$g/m^3$ and 19mJ respectively. Minimum ignition energy was shown at the 4 and 5mm gap distance of discharge electrode, and when the gap distance was below 2mm the explosion could not generated although the sufficient energy was given. It was also found that the ignition energy decreased linearly with the decreasing of dust mean particle size.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1707-1709
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• 2002

Ionic wind may be produced by DC corona discharges. In this work, the electrical effect has studied to evaluate applicability in fields of electrostatic cooling, ozone generation, electrostatic precipitation, heat transfer, air flow modification, and etc. The ionic wind velocity was measured as a function of the distance of pin to plate and the diameter of punched hole. The pin to punched-plate electrode generates airflow from pin to plate and the flow direction is controlled by the hole size of punched-plate, input voltage and distance between two electrodes. As a consequence, the ionic wind velocity is nearly proportional to the applied voltages and ranges from 1 to 3 m/sec.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.495-496
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• 2006

Electrostatically actuated nanoscale tweezers are fabricated on micro processed electrodes using FIB-CVD. Heavily doped electrode works as interconnection platform for controlling nanoscale devices. Short bent pillars are deposited to control the gap distance of main tweezers fabricated on bent ones. Two types of tweezers which have different gap distances are fabricated and tweezing motion was successfully demonstrated. The threshold voltages at snap-down of the pillars are dependent on the initial gap distance of the unactuated pillars, and the measured values were 93V for 3.6um and 30V for 2.2um. The dimension of nano tweezers and initial gap distances are controllable as demonstrated and we expect more complicated 3-dimensional shapes are also possible.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.362-365
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• 2002

This paper, experiment manufactures device of Metal/Poly-${\gamma}$ Benzyl $_D$-GlutamateOrganic Films/Metal structure using PBDG and I-V properties and C-F properties. The I-V characteristic is measured that approve voltage from 0 to +2[V] of device and the distance between electrode is larger, could know that small current flow and thin film could know that had insulation property. C-F characteristic has each other affinity between the polarization amount and frequency. Permittivity of MIM device could know by dipole that is voluntary polarization of LB film that polarization is happened. The capacitor properties of a thin film is better as the distance between electrodes is smaller.