• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.3
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• pp.130-134
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• 2009

A new long persistent phosphors of $CaZrO_3$ was synthesized at high temperature with weak reduction atmosphere by a traditional solid state reaction method. Photoluminescence spectra analysis showed that the $CaZrO_3$ doped with $Tb^{3+}$ emitted green-yellow emission caused by the energy level transition from the $^5D_3$ and $^5D_4$ to $^7F_1{\sim}^7F_6$. The main emission spectra of 542 nm peak by the $^5D_4{\rightarrow}^7F_5$ transition was revealed through synthesizing at high temperature in $N_2$ gas atmosphere. The afterglow emission spectra of $CaZrO_3:Tb^{3+}$ long persistent phosphores arise at 546 nm peak of narrow range. After the 254 nm ultraviolet light excitation source was switched off, the green-yellow long persistent phosphor can be observed which could last for 8 h in the limit of light perception of dark-adapted human eyes ($0.32\;mcd/m^2$).

• Membrane Journal
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• v.6 no.4
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• pp.219-226
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• 1996

Rotary disc ultrafiltration module(RDM) was developed for the separation of oil emulsions. This module was devised to reduce the gel polarization phenomenon by alecoupling the operation pressure and the surface velocity of solution in ultrafiltration(UF) processes. Two-shaft engaged disc type RDM having 20 rotary disc membcanes(UOP, USA) was operated under 85kPa vacuum at $25^{\circ}$C. The pressure drop due to slip flow in the two-shaft RDM was found to be proportional to $(2.5{\omega}r)^{2}$. The pure water flux of two-shaft RDM decreased by 9.95% at the angular velocity of 41.89rad/s compared to the decrease of 3.01% for one-shaft RDM at the same velocity. When the angular velocity was changed from 31.42rad/s to 2.62rad/s, the flux decline for 1% cutting oil in two-shaft RDM was 30.16% that is similar to that of one-shaft RDM. Disc gap of 3mm and 7mm did not show any significant differences in the flux for 1% cutting oil solution. A modified model for two-shaft RDM showed good agreement with the experimental results for the cutting oil solution.

• Journal of Sensor Science and Technology
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• v.9 no.5
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• pp.373-379
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• 2000

In this paper, an estimation system of vehicle position and orientation on magnetic lane, which is a parameter of the steering controller for automated lane following is described. To verify that the magnetic dipole model could be applied to a magnetic unit paved in roadway, the analysis of the model is compared with the data of 3-axis magnetic field measured experimentally. The sensor location could be estimated by analysis of the model based on experimental data. For the magnetic lane model merged magnetic unit, the relation of sensor location and magnetic field is acquired experimentally. The proposed estimation of vehicle position and orientation is adopted to automated lane following by computer simulation.

• Proceedings of the Korean Society of Computer Information Conference
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• 2010.07a
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• pp.99-102
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• 2010

스마트폰의 도입으로 인하여 증강현실이 널리 알려짐에 따라 대중들의 관심은 이에 집중되고 있으며 휴대성으로 인하여 모바일 기기에서의 증강현실 연구가 하나의 흐름으로 자리 잡고 있다. 기존의 증강 현실 관련 응용 기술들이 많이 연구되고 있지만 실제 게임에서 사용되고 있는 인공 지능과 결합된 연구는 이루어지고 있지 않다. 본 논문에서는 스마트 폰의 기능중 하나인 3축 가속도 센서를 이용하여 증강 현실 환경에서 3D 에이전트의 상태를 동적으로 변환하는 인공 지능 알고리즘을 제안한다. 인공지능이 적용된 에이전트의 상태를 제어하기 위한 전통적인 방식으로서 사용자가 직접 입력해 주거나 이를 인식하는데 마커를 사용하여 해결하였다. 본 논문에서는 증강 현실 구현을 위해 마커리스 추적 기술을 사용하였고 3축 가속도 센서를 이용하여 동적으로 에이전트의 상태를 변환하도록 하였다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.05a
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• pp.310-313
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• 2002

본 연구는 공간특성이 서로 다른 두 공간, 주거/사무공간의 조명환경에 대한 평가구조를 비교 검토하고 각 공간의 행위에 적합한 조명환경을 제시하고자 슬라이드 사진을 이용한 평가실험을 실시하였다. 평가대상 슬라이드수는 주거공간이 28장, 사무공간이 26장이다 실험은 각 공간별로 분위기항목과 행위항목에 대해 각각 실시하였다. 평가항목은 분위기항목이 21가지, 행위항목이 14가지이다. 각 공간의 평정치를 이용하여 인자분석을 실시한 결과, 주거공간과 사무공간 모두 <활동성>,<안정감),<고급감)의 3인자축이 추출되었다. 그러나, 주거공간의 경우는 <활동성>인자축이 평가축을 이루었으며, 사무공간의 경우는 <고급감>인자축이 평가축을 이루었다. 행위항목의 인자분석 결과는 주거공간의 경우, <작업행위>,<휴식행위>,<단란행위>의 3인자축이, 사무공간의 경우 <작업행위),<휴식행위>의 2인자축이 추출되어 주거공간의 경우, 활동성 평가가 높은 조명환경은 작업행위에 적합하며 반대로 활동성평가가 낮은 조명환경일수록 휴식행위에 적합한 것으로 나타났다 사무공간의 경우도 마찬가지로 작업행위에 가장 큰 영향을 미치는 분위기 인자는 활동성으로 나타나 활동성평가 높을수록 작업행위에 적합하며, 후식행위는 평가성 평가가 높은 조명환경에 적합한 것으로 나타났다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.370-375
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• 2010

Tungsten carbide microshaft is used as micro punch, electrode of micro electro discharge machining, and micro tool because of its high hardness and rigidity. In this research, tungsten carbide microshaft was fabricated using electrochemical machining. $H_2SO_4$ solution was used as the electrolyte because it can dissolve tungsten carbide and cobalt simultaneously. Experimentally studied were the effects of electrolyte concentration, machining time, and machining voltage on material removal rate and the shape of the microshaft. To eliminate the effects of bubbles and metal corrosion layer on microshaft shape, the machining was performed below the electrolysis voltage. Three step electrochemical process was suggested to fabricate the straight tungsten carbide microshaft. As a result, a straight tungsten carbide microshaft of $30{\mu}m$ in diameter and $500{\mu}m$ in length was obtained through the proposed three step electrochemical process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.123-123
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• 2003

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.2
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• pp.63-71
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• 2003

This paper presents a robust slewing control of a flexible space structure based on sliding surface design. A sliding surface is designed for a single-axis rest-to-rest slewing in view of target angle, target angular velocity, and root monent of the flexible appendage. In comparison with the Lypunov control law, both controllers guarantee the stability and command tracking capabilities for nominal system. It is also shown that the designed control law provides further robustness to internal/external uncertainties. Extending the results of a single-axis maneuver, a sliding mode control law was sought for an arbitrary three-axis maneuver. Quaternion was used to determine the attitude of a space structure and sliding surfaces were designed for each axis, thereby a robust control law was derived considering the coupling effects between each rotational axis during the maneuver. Several numerical examples were demonstrated to show the effectiveness of the designed control law.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.160-165
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• 2014

In this study, an efficiency test was performed by fabricating MEMS (Micro Electro Mechanical Systems) based 3-axis acceleration sensor modules and an earthquake monitoring system was composed. Data acquisition device (NI-9239) with a 24bit ADC (Analog to Digital Converter) was used for improving the performance of 3-axis acceleration sensor modules and filtered data (100Hz Low Pass Filter) was used for reducing noises. Also this paper focused on detecting meaningful vibration in the building by developing the earthquake monitoring software. If vector sum of 3-axis acceleration is greater than the preset value, the value will be recorded and saved to the file.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.2
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• pp.107-120
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• 2014

First purpose of this study is to build Korean mountain ridgelines based on GIS by using spatial information and analyze natural environment around mountain ridgelines built before. Second purpose of this study is to integrate Korean ridgelines and natural environment built before and then provide the integrated information related to ridgelines for public. To do so, fist of all, Korean mountain ridgelines including Deagan, Jeongmeak, Gimeak, Jimeak, are built as spatial information. Second, Encoding of mountain ridgelines is conducted to analyze main and divaricate ridgelines systematically as grades of ridgelines. Third, based on spatial information, present condition using natural environment including geographical information, ecological zoning map, environmental conservation value assessment map, is analyzed. Finally, as a method integrating and using the aforementioned three information, the system providing integrated information based on GIS is proposed, To build the GIS data of Gimeak and Jimeak, they should be analyzed in more detail than Beakdu Deagan and Jeongmeak, so existing methodology to build mountain ridgelines based on GIS is improved. According to the distance of each mountain ridgeline, they are separated into five grades, and encoding of each mountain ridgeline based on Beakdu Deagan is applied to all mountain ridgelines to figure out the present condition of ridgelines themselves. In addition, according to the distance of each mountain ridgeline, it is separated into three areas: core, buffer, median zone. Based on three zones, the way to make use of the information efficiently related to mountain ridgelines is proposed. This study systematizes Korean mountain ridgelines which did not have systematic structures and then analyzes systematic mountain ridgelines. Based on this analysis, this study finds the way to makes use of information related to mountain ridgelines effectively.