• 전자공학회논문지D
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• 제35D권5호
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• pp.80-86
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• 1998

Material characterizations were performed for In$_{0.53}Ga_{0.47}As/In$_{0.52}Al_{0.48}$/As MQWs grown on InP substrates by low-temperature modlecular beam epitaxy. MQW samples were grwon at different temperatures of 200.deg.C, 300.deg. C and 500.deg. C, and doped with 10$^{18}$ cm$^{3}$ Be. High resolution x-ray diffraction measurement showed the change in crystal qualities according to growth temperature. Hall measurement showed the changes in carrier concentrations and mobilities for different growth temperatures. The optical properties of MQW samples were investigated with photoluminescence and fourier-transform infrared spectroscopy measurements.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.501-502
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• 2008

In this study, P-doped ZnO thin films were prepared on sapphire substrates by pulsed laser deposition and annealing method. The electrical properties were investigated as a function of annealing temperatures at a fixed oxygen pressure. The XRD measurement showed that p-doped ZnO thin films were c-axis oriented. The Hall measurement showed that p-type ZnO thin film was observed. The carrier concentration of $1.18{\times}10^{16}cm^{-3}$ and the mobility of $0.96\;cm^{-3}/Vs$ were obtained for the P-doped ZnO thin film fabricated annealing temperature $850^{\circ}C$.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.103-106
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• 2000

We have studied the magnetic properties in Bi$_2$Sr$_2$CaCu$_2$O$_8$ single crystal with columnar defects using micro Hall-probe array. We found that fold profiles inside sample were similar to the Bean's critical state model from the magnetic hysteresis measurement. In the magnetic relaxation measurement, the normalized relaxation rates were maximum near the center and decreased toward the edge of the sample expect zero gauss. The relaxation rates as a function of the temperature were maximum near the 40K and rapidly decreased both sides of the peak.

• 한국정밀공학회지
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• 제13권6호
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• pp.136-144
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• 1996

We developed a part of stroke sensing cylinder for position control of automatic excavator and its measurement system. In this paper, for development of stroke sensing cylinder, we consist of 2-axis control instrument system with Hall sensor. A performance of piston rod with magnetic scales is evaluated by the developed measurement system. Furthermore, the position control for good performance of instrument system is achieved by a sliding mode control which is a new method diminishing the chattering in that control by setting 2-dead band along the swtching line. The unknown parameters for sliding mode control are estimated by the signal compression method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.404-405
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• 2007

Tin-doped indium thin film is outstanding material among transparent Conductive Oxide (TCO) materials. ITO thin films show a low electrical resistance(<$10^{-4}\;[{\Omega}{\cdot}m]$) and high transmittance(>80%) in the visible range. ITO thin films usually have been deposited on the glass substrate. In order to apply flexible display, the substrate should have the ability to bend and be deposited without substrate heat. Also properties of ITO thin film depend on what kind of substrate. In this study, we prepared ITO thin film on the polycarbonate (PC) substrate by using Facing Target Sputtering (FTS) system. Before deposition of ITO thin film, PC substrate took plasma surface treatment. The electrical and surface properties of as-deposited thin films were investigated by Hall Effect measurement, UV/VIS spectrometer and the surface property of substrate is investigated by Contact angle measurement.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.159-160
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• 2006

$AgGaSe_2$ single crystal thin films grown by using hot wall epitaxy (HWE) system. The single crystal thin films were investigated by photoluminescence and double crystal X-ray diffraction(DCXD) measurement. From the photoluminescence measurement of $AgGaSe_2$ single crystal thin film, we observed free excition ($E_x$) observable only in high quality crystal and neutral bound exciton ($D^{\circ}$,X) having very strong peak intensity. And, the full width at hall maximum and binding energy of neutral donor bound excition were 8 meV and 14.1 meV, respectively. By Haynes rule, an activation energy of impurity was 141 meV.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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• pp.91-97
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• 1996

We have all heard sounds that did not sound "right" while riding in an automobile. Objectionable sounds are difficult to find and understand because the sound field is complex and dynamic in the near field of an automobile. Many different noise sources and transmission paths must be understood before an engineering change can be recommended. This paper reviews the fundamental characterization of sound and chscusses the Sound Intensity measurement technique. Sound intensity measurements locate sources and sinks of acoustic energy. Used with narrowband analysis equipment, acoustic noise sources can be identified. Sound intensity measurements are made -in-situ and do not require specmi anechoic facilities. The measurement results in a vector representation of the near field sound field and can discriminate between multiple sound sources.d sources.

• 한국결정성장학회지
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• 제14권6호
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• pp.253-256
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• 2004

단결정상의 ZnO 에피 박막 성장을 사파이어 기판의 (0001)면 상에 RF magnetron sputtering 법으로 수행하였다. 200～$600^{\circ}C$까지의 기판의 온도를 변화하여 가면서 ZnO 에피 박막의 성장 거동을 조사하였으며, 성장된 ZnO 박막에 대하여 산소분위기에서 400, 600, $800^{\circ}C$에서 각각 아닐링을 하여 이에 대한 광 특성을 평가하였다. Hall measurement에 의해 측정 된 carrier concentratin은 $600^{\circ}C$에서 아닐링하여 $2.6${\times}$10^{16}\textrm{cm}^{-3}$이었다.

• Transactions on Electrical and Electronic Materials
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• 제7권1호
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• pp.36-41
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• 2006

In this paper, the time evolution of undoped GaN epilayers on a low-temperature GaN buffer layer grown on c-plane sapphire at a low pressure of 300 Torr was studied via a two-step growth condition in a horizontal MOCVD reactor. As a function of the growth time at a high-temperature, the surface morphology, structural quality, and optical and electrical properties were investigated using atomic force microscopy, high-resolution x-ray diffraction, photoluminescence, and Hall effect measurement, respectively. The root-mean-square roughness showed a drastic decrease after a certain period of surface roughening probably due to the initial island growth. The surface morphology also showed the island coalescence and the subsequent suppression of three-dimensional island nucleation. The structural quality of the GaN epilayer was improved with increasing growth time considering the symmetrical (002) and asymmetrical (102) rocking curves. The variations of room-temperature photoluminescence, background carrier concentration, and Hall mobility were measured and discussed.

• Transactions on Electrical and Electronic Materials
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• 제13권5호
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• pp.241-244
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• 2012

Antimony doped tin oxide (ATO) thin films on glass substrate were prepared by the chemical solution deposition (CSD) method, using sol-gel solution synthesized by non-alkoxide precursors and the sol-gel route. The crystallinity and electrical properties of ATO thin films were investigated as a function of the annealing condition (both annealing environments and temperatures), and antimony (Sb) doping concentration. Electrical resistivity, carrier concentration, Hall mobility and optical transmittance of ATO thin films were improved by Sb doping up to 5~8 mol% and annealing in a low vacuum atmosphere, compared to the undoped tin oxide counterpart. 5 mol% Sb doped ATO film annealed at $550^{\circ}C$ in a low vacuum atmosphere showed the highest electrical properties, with electrical resistivity of about $8{\sim}10{\times}10^{-3}{\Omega}{\cdot}cm$, and optical transmittance of ~85% in the visible range. Our research demonstrates the feasibility of low-cost solution-processed transparent conductive oxide thin films, by controlling the appropriate doping concentration and annealing conditions.