• 대한기계학회논문집A
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• 제29권2호
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• pp.311-317
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• 2005

NC controller parameters are fixed when the controller is combined with a machine. However, the characteristics of controller could be changed as it has being used by the machine or other environmental conditions. Ultimately, it results in tool positioning accuracy changing. The loading torque in servo motor also influences on the positioning accuracy. This study focus on a measuring and analysing method for verifying the angular positioning accuracy of NC servo motor. We used a high resolution A/D converter for acquiring analogue signal of rotary encoder in servo motor. Generating tool path by the combination of axial movements (X,Y,Z) is compared with the encoder signals with the servo motor torque. The current variation signal is also read from the servo motor power using a hall sensor and converted to the motor torque. The method of analysing proposed in this study will be used for determining the gains (tuning) of parameter in NC controller, when the controller is set up at a machine initially or the controller condition is changed during the work.

• 한국음향학회지
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• 제36권5호
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• pp.321-328
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• 2017

본 연구는 실제 콘서트홀에서의 무대음향측정과 무대 위 연주평가를 통해 듀엣연주자의 무대음향 선호요인을 도출한 것이다. 실험은 1186석 규모의 공연장에서 진행하였으며, 무대에는 오케스트라 쉘(Orchestra Shell)이 설치되었다. 실험에는 15쌍(총30명)의 연주자가 참여하였고, 선별된 5개 위치에서 순서에 따라 쌍을 지어 자기연주에 따른 각 지점의 선호도를 평가하였다. 그 결과, 무대 중앙의 선호도가 가장 높은 것으로 나타났으며, CS(Clarity at stage) 및 $ST_{Late}$가 가장 유의한 선호요인으로 도출되었다.

• 환경위생공학
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• 제21권1호
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• pp.58-65
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• 2006

This study is measured in at ozone concentrated places in school and outside of school where places that use copy machine and the others do not use one. Library copy room, Search room, Y-Copy, J-copy, R-shop are the places using copy machines and Search room, K-apt, J-billiard hall are the opposite. The measurement was held three times a day-the morning, the afternoon and the evening-once for each at indoor and outdoor. 8 places were lower than domestic ozone concentration standard(0.06ppm). The indoor ozone concentration average was the highest in Search room of school and was the lowest in Library restroom. The outdoor ozone concentration average was the highest in J-billiard hall.

• 한국표면공학회지
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• 제38권1호
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• pp.7-13
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• 2005

Bismuth thin films were prepared on glass substrate with RF magnetron sputtering and effects of substrate temperature on surface morphology and their electrical transport properties were investigated. Grain growth of bismuth after nucleation and the onset of coalescense of grains at 393 K were observed with field emission secondary electron microscopy. Continuous thin films could not be obtained above 473 K because of grain segregation and island formation. Hall effect measurements showed that substrate heating yields the decrease of carrier density and the increase of mobility. Resistivity of bismuth film has its minimum (about 0.7 x 10/sup -3/ Ωcm) in range of 403～433 K. Annealing of bismuth films deposited at room temperature was carried out in a radiation furnace with flowing hydrogen gas. The change of resistivity was not significant due to cancellation of the decrease of carrier density and the increase of mobility. The abrupt change of electrical properties of film annealed above 523 K was found to be caused by partial oxidation of bismuth layer in x-ray diffraction analysis.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.326-329
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• 2007

$CuInS_{2}$ thin films were synthesized by sulpurization of Cu/In Stacked elemental layer deposited onto glass Substrates by vacuum furnace annealing at temperature 200[$^{\circ}C$]. And structural and electrical properties were measured in order to certify optimum conditions for growth of the ternary compound semiconductor $CuInS_{2}$ thin films with non-stoichiometry composition. $CuInS_{2}$ thin film was well made at the heat treatment 200[$^{\circ}C$] of SLG/Cu/ln/S stacked elemental layer which was prepared by thermal evaporator, and chemical composition of the thin film was analyzed nearly as the proportion of 1 : 1 : 2. Physical properties of the thin film were investigated at various fabrication conditions substrate temperature, annealing and temperature, annealing time by XRD, FE-SEM and Hall measurement system. At the same time, carrier concentration, hall mobility and resistivity of the thin films was $9.10568{\times}10^{17}$ [$cm^{-3}$], 312.502 [$cm^{2}/V{\cdot}s$] and $2.36{\times}10^{-2}$ [${\Omega}{\cdot}cm$], respectively.

• 전자공학회논문지D
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• 제34D권12호
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• pp.46-53
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• 1997

The TMA gas sensors are fabricated with the ZnO-based thin films grown by a RF magnetron sputtering method. The hall effect measurement and AES analysis are carried out to investigate the effects of the sputtering gases and dopants which effect on the electrical resistivity and sensitivity to TMA gas. We measure the cfhanges of the surface carrier concentration, haall electron mobility, electrical resistivity, surface condition, and depth profile of the films. The ZnO-based thin film sensors sputtered in oxygen, or added with dopants showed a high sruface carrier concentration, film sensors sputtered in oxygen and doped with 4.0 wt.% $Al_{2}$O$_{3}$, 1.0 wt.% TiO$_{2}$, and 0.2 wt% v$_{2}$O$_{5}$ showed the highest surface carrier concentration of 5.952 * 10$^{20}$ cm$^{-3}$ , hall electron mobility of 176.7 cm$^{2}$/V.s, lowest electrical resistivity of 6*10$^{-5}$ .ohm.cm and highest sensitivity of 12. These results were measured at a working temperature of 300.deg. C to 8 ppm TMA gas.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 하계학술연구발표회 및 한.일 공동심포지엄
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• pp.154-155
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• 2003

Substituting transition metals such as V, Cr, Mn, Fe, Co and Ni into semiconductors have been of interest because of its unique electrical and magnetic properties. It was reported that the magnetoresistance(MR) ratio of CrGe was 1.7% and 1 4% at 120 K in fields of 0.5 and 5 T, respectively. The MR ratio of FeGe was 19% at 180K. The electrical resistivity of CrGe changed according to Cr concentration. In this talk, we report transport properties of V-doped Ge single crystals with several different V concentrations. The carrier densities and mobilities will be determined from Hall measurement.

• 대한전자공학회논문지
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• 제20권5호
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• pp.50-55
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• 1983

본 논문에서는 여러 가지 이온 도우스와 열처리 온도에 대해서 hall-effect/sheet resistivity 측정방법을 이용하여 실리콘을 주입한 크롬이 도핑된 GaAs의 전기적 성질에 관한 연구를 하였다. 시료는 상온에서 이온을 주입하였으며 실리콘 나이트라이드 캘핑을 하여 15권동안 수소수국기에서 열처리하였다. 연구된 모든 도우스에서 n형 층이 형성되었으며 최적 열처리 온도는 850℃이었다. 크롬이 도핑된 GaAs기판에 대해 최대 전기적 활성화 효률은 89%이었다. 캐리어 농도와 이동도의 depth profile은 이온 도우스와 열처 이에 매우 의존적이다. 800노의 열처리 후에도 이온 주입에 의해 생긴 손상이 일부 존재하고 있었으며 900℃ 열처리에서는 주입된 실리콘 이온의 약부확산과 외류확산이 있었다.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권8호
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• pp.451-458
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• 2000

The precise speed and position control technique for Brushless DC Motor demands accurate position and speed feedback information. Generally, resolver or absolute encoders are used as speed and positiion sensor. But they increase cost and more problem happens at low speed than high speed specially. Therefore, in this paper, optimal speed observer is proposed for decreasing size and cost of whole system. And also, we consider the error problem about the system modeling and measurement at low speed range as well as high speed. The overall system consists of two parts, a drive and a speed observer. We make use of Least square curve fitting algorithm as speed observer and can overcome low resolution by proposed observer. Also, because of using the signal of hall sensor, robust control is possible in low speed as well as high speed for the change of the parameters of the system and disturbance. To construct observer using the signal of hall sensor, we design the pulse multiplier circuit and the software of microprocessor, AT89CC2051. Finally, the performance of the proposed observer is exemplified by some simulations and experiments.

• 한국표면공학회지
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• 제47권4호
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• pp.181-185
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• 2014

We investigated the structural, electrical and optical characteristics of IGZO thin films deposited by a room-temperature RF reactive magnetron sputtering. The thin films deposited were annealed for 2 hours at various temperatures of 300, 400, 500 and $600^{\circ}C$ and analyzed by using X-ray diffractometer, transmission electron microscopy, atomic force microscope and Hall effects measurement system. The films annealed at $600^{\circ}C$ were found to be crystallized and their surface roughness was decreased from 0.73 nm to 0.67 nm. According to XPS measurements, concentration of oxygen vacancies were decreased at $600^{\circ}C$. Optical band gap were increased to 3.31eV. The carrier concentration and Hall mobility were sharply increased at 600oC. Our results indicate that the IGZO films deposited at a room temperature can show better thin film properties through a heat treatment.