• Journal of the Mineralogical Society of Korea
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• v.29 no.3
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• pp.89-101
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• 2016

This study investigated spectral characteristics of heavy metal contaminated soil samples in the vicinity of abandoned Boksu mine. Heavy metal concentrations including arsenic, lead, zinc, copper and cadmium were analyzed by XRF analysis. As a result, all of the soil samples excluding control sample were over-contaminated based on the counter measure standard. The XRD results revealed that quartz, kaolinite and smectite were detected for all of the soil samples and heavy metals in soil were adsorbed on clay minerals such as kaolinite and smectite. The spectral analyses confirmed that spectral reflectance of near-infrared and shorter portion of shortwave-infrared spectrum decreases as heavy metal concentration increases. Moreover, absorption depths at 2312 nm and 2380 nm, the absorption features of clay minerals, decreases with higher heavy metal concentration indicating adsorption of heavy metal ions with clay minerals. It indicates that spectral features and heavy metal contamination of soil samples have high correlations.

• Journal of the Mineralogical Society of Korea
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• v.31 no.2
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• pp.75-86
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• 2018

This study analyzed precipitation environment, heavy metal concentration, mineral composition, and spectral characteristics associated with heavy metal concentration and mineral composition for the reddish brown precipitates occurred in the drainage of Dogye mining station. The pH of the reddish brown precipitates ranges from 7.59 to 7.94 resulting neutral. XRF analysis reveals that the precipitates has high Fe concentration, and contaminated with Ni, Cu, and Zn. Dolomite, calcite, goethite, magnetite, kaolinite, pyrophyllite, quartz and aluminum isopropoxide were identified based on XRD analysis. As a result of spectral analysis associated with heavy metal contamination, visible reflectance increases and infrared reflectance decreases with a increase in heavy metal concentration. The spectral characteristics of the reddish brown precipitates is turned out to be manifested by goethite, magnetite, kaolinite, pyrophyllite and aluminum isopropoxide.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.298-299
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• 2012

현재 반도체 나노구조는 단전자 트랜지스터, 레이저, LED, 적외선 검출기 등과 같은 고효율 광전자 소자에서의 응용을 위해 활발한 연구가 진행 되고 있다. 이러한 응용 분야를 위한 다양한 종류의 나노구조 성장이 광범위하게 시도 되고 있지만 주로 III-V 족 화합물 반도체에 대한 연구가 주를 이룬 반면 II-VI 족 화합물 반도체에 대한 연구는 아직 미흡하다. 하지만 II-VI 족 화합물 반도체는 III-V 족 화합물 반도체와 비교했을 때 더 큰 엑시톤 결합에너지(exciton binding energy)를 가지는 우수한 특성을 보이고 있으며 이러한 성질을 가지는 II-VI 족 화합물 반도체 중에서도 넓은 에너지 갭을 가지는 CdTe 양자점은 녹색 영역대의 광전자 소자로서 활용되고 있다. 본 연구에서는 분자 선속 에피 성장법(molecular beam epitaxy; MBE)과 원자 층 교대 성장법(atomic layer epitaxy; ALE)으로 CdTe 두께에 따른CdTe/ZnTe 나노구조의 광학적 특성을 연구하였다. 광루미네센스(photoluminescence; PL)를 통해 CdTe/ZnTe 나노구조에서 CdTe 두께에 따른 에너지 밴드와 열적 활성화 에너지를 관찰하였다. 또한 시분해 광루미네센스(Time-resolved PL)를 통해 CdTe 두께에 따른 CdTe/ZnTe 나노구조의 운반자 동역학을 조사하였다. 저온 광루미네센스 측정 결과 CdTe 두께가 증가할수록 각 샘플의 피크는 더 낮은 에너지 영역대로 이동하는 것을 관찰할 수 있다. 1.2 에서 2.0 ML로 증가할 때 광 루미네센스의 작은 적색편이를 관찰할 수 있는데, 이는 CdTe 양자우물에서 양자점으로의 구조적인 전이가 일어남에 따라 구속효과가 증가하였기 때문이다. 또한 2.0 에서 3.6 ML까지 CdTe 두께가 증가할 때 측정된 적색편이 현상은 양자점의 사이즈 증가함에 따른 것이다. 마지막으로 3.6 에서 4.4 ML로 CdTe 두께가 증가할 때 큰 적색편이 현상을 볼 수 있는데 이는 CdTe 양자점에서 양자세선으로의 구조적 전이에 따라 구속효과가 증가하였기 때문이다. 온도 의존 광루미네센스(Temperature-dependent PL) 측정 결과 1.2 와 3.0 ML 두께의 CdTe/ZnTe 나노구조에서 구속된 전자의 열적 활성화 에너지가 18 과 35 meV로 관찰되었다. 3.0 ML CdTe/ZnTe 나노구조에서 가장 큰 열적 활성화 에너지를 갖는 것은 양자점의 균일도가 좋아지고 저차원 나노구조로의 구조적 전이가 일어나면서 운반자 구속효과에 다른 쿨롱 상호작용이 증가하였기 때문이다.

• Conservation Science in Museum
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• v.23
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• pp.71-90
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• 2020

The scientific analysis of a 'F-51D Mustang Fighter'(Registered Cultural Heritage 666), one of the War Memorial of Korean collections, was carried out. The paint layer and canopy were discolored due to a constant outdoor exhibit. The results obtained through the scientific survey and analysis processes were intended to be used as basic data for the future dismantling and restoration of the fighter. The analysis results for the pigment components have confirmed red oxide of iron, Fe₂O₃ organic pigments, such as Cobalt Blue, phthalocyanine blue, etc., yellow PbCrO₄, white TiO₂, black Fe₃O₄, and gray Fe₃O₄ + TiO₂. It has been also confirmed that Alkyd resin was mainly used for painting. The fighter's canopy was Poly methyl methacrylate(PMMA), and Al was detected as the main component of the fighter body, wings, and tails.

• Journal of Conservation Science
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• v.29 no.4
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• pp.437-444
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• 2013

We studied for the chemical characterizations of the charred residues obtained from the ancient potteries in the Proto-Three Kingdom period from archaeological sites in Joong-do, Chuncheon. Organic components of the charred residues were extracted and analysed using mass spectrometry and infrared spectroscopy. Lipid profiles from these samples were not identified in gas chromatography-mass spectrometry. Bulk stable isotope analyses of charred residues was used to infer an average values of the foods prepared. The average carbon isotope values (${\delta}^{13}C$) of the residues are $-14.7{\pm}2.8$‰ (ranging from -8.7‰ to -18.4‰, n=9), and nitrogen isotope values (${\delta}^{15}N$) are $6.2{\pm}1.1$‰ (ranging from -4.4‰ to -7.6‰, n=9). This is the first approach to analyse charred residues using stable isotopic method in Korea. Charred food residues on the interior surface of archaeological pottery can provide valuable information about pottery use and dietary habits of its population.

• Journal of Conservation Science
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• v.34 no.2
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• pp.107-118
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• 2018

This report does studied for making the method of conserving bracket murals in Daeungjeon of Jikjisa Temple, through the scientific way. Results of evaluated the conservation status at the braket mural paintings, most serious damage is structural damage like cracks, breakage, and delamination. After optical investigation, a characteristic point wasn't found such as underdrawing or traces of a coat of paint. The ultrasonic examination speed by each wall painting was measured from about 195.8 m/s to 392.7 m/s, according to the location of the surface, and it was able to compare the surface properties according to the location. In Infrared-thermal image measurement shows that wall layer separation and paint layer delamination are closely detected, therefore it was able to judge of damage on the objective way. Material analysis revealed that the walls were made by sand and weathering soil. The wall layer combined sand with less than fine sand size by nearly 5:5, and the finishing layer was found to have mixed medium sand and fine sand at approximately 6:4 rates. However, In case of finishing layer, mixing ratios of sizes less than very fine sand were found to be significantly lower than wall. Therefore, it is estimated that the plysical damage such as the separation between the layers of the walls created in the braket mural paintings, is continuously caused by changes in the internal stresses and volume ratio caused by the density differences between the wall and the finishing layers.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.8
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• pp.28-34
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• 2000

Pyroelectric properties of the $Pb(Zr_{0.9}Ti_{0.1})O_3$ ceramics having the rhombohedral structure have been studied by using the dynamic measurement method. The pyroelectric responses of the $Pb(Zr_{0.9}Ti_{0.1})O_3$ ceramics are characterized in both low and high medulation frequency regions and their frequency depences are observed. In the low frequency region (2~200Hz), the change of polarization increases and shows the maximum since the reorientation rate of domains is higher than the modulation frequency. Inthe high frequency region (200~2000Hz), the pyroelectrci response decreases as the frequency increases, because the reorientation of domains is suppressed and so the change of polarization decreases. Pyroelectric coefficient, figure of merit, noise equivalent power and detectivity of the $Pb(Zr_{0.9}Ti_{0.1})O_3$ ceramics are measured as $1.6{\times}10^{-8}C/cm^2{\cdot},\;1.6{\times}10^{-11}C{\cdot}cm/J,\;2.4{\times}10^{-7}W/Hz^{1/2}\;and\;4.17{\times}10^6cm{\cdot}Hz^{1/2}/W$, respectively.

• Publications of The Korean Astronomical Society
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• v.21 no.2
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• pp.67-74
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• 2006

We have developed a control electronics system for an infrared detector array of KASINICS (KASI Near Infrared Camera System), which is a new ground-based instrument of the Korea Astronomy and Space science Institute (KASI). Equipped with a $512{\times}512$ InSb array (ALADDIN III Quadrant, manufactured by Raytheon) sensitive from 1 to $5{\mu}m$, KASINICS will be used at J, H, Ks, and L-bands. The controller consists of DSP(Digital Signal Processor), Bias, Clock, and Video boards which are installed on a single VME-bus backplane. TMS320C6713DSP, FPGA(Field Programmable Gate Array), and 384-MB SDRAM(Synchronous Dynamic Random Access Memory) are included in the DSP board. DSP board manages entire electronics system, generates digital clock patterns and communicates with a PC using USB 2.0 interface. The clock patterns are downloaded from a PC and stored on the FPGA. UART is used for the communication with peripherals. Video board has 4 channel ADC which converts video signal into 16-bit digital numbers. Two video boards are installed on the controller for ALADDIN array. The Bias board provides 16 dc bias voltages and the Clock board has 15 clock channels. We have also coded a DSP firmware and a test version of control software in C-language. The controller is flexible enough to operate a wide range of IR array and CCD. Operational tests of the controller have been successfully finished using a test ROIC (Read-Out Integrated Circuit).

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.161-161
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• 2010

InAsSb alloy system 은 HgCdTe 를 대체하는 적외선 광소자 및 검출기 등에 응용이 가능한 유망한 물질이지만 정확한 유전함수 및 전이점의 연구는 미흡한 실정이다. 본 연구에서는 타원 편광 분석법을 이용하여 1.5 ~ 6 eV 의 분광 영역에서 As 조성비를 각기 (x = 0, 0.127, 0.337, 0.491, 0.726 및 1.00) 다르게 한 $InAs_xSb_{1-x}$ alloy의 유전함수를 측정하였다. 또한 표면에 자연산화막을 제거하기 위하여 Methanol 과 DI Water 로 표면을 세척 한 후 $NH_4OH$, Br in Methanol, HCl 등으로 적절한 화학적 에칭을 하여 산화막을 제거함으로서 순수한 InAsSb 의 유전함수를 측정할 수 있었다. 측정된 InAsSb 유전함수를 Standard analytic critical point line shape 방법으로 As 조성비에 따른 에너지 전이점을 얻을 수 있었다. 또한 얻어진 에너지 전이점 값을 이용하여 linear augmented Slater-type orbital 방법으로 전자 밴드 구조 계산을 하였고, 이를 바탕으로 $E_0$, $E_1$, $E_2$ 전이점 지역의 여러 전이점 ($E_1$, $E_1+\Delta_1$, $E_0'$, $E_0'+\Delta_0'$, $E_2$, $E_2+\Delta_2$, $E_2'$, $E_2'+\Delta_2$, $E_1'$) 의 특성을 정확히 정의할 수 있었다. 또한 As 조성비가 증가하면서 $E_2$, $E_2+\Delta_2$, $E_2'$, $E_2'+\Delta_2$ 전이점들이 서로 교차 되는 것을 발견하였고, 저온에서만 관측이 가능하였던 InSb 의 두 saddle-point (${\Delta_5}^{cu}-{\Delta_5}^{vu}$, ${\Delta_5}^{cl}-{\Delta_5}^{vu}$)를 상온에서 찾아내었다. 타원 편광 분석법을 이용한 전이점 연구 및 물성 분석은 InAsSb alloy 의 광학적 데이터베이스를 확보하는 성과와 더불어 새로운 디바이스기술 및 광통신 산업에도 유용한 정보가 될 것이다.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.4
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• pp.91-100
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• 2009

In this paper, we propose autonomous intelligent wheelchair system which recognize the commands using the gaze recognition and avoid the detected obstacles by sensing the distance through range sensors on the way to driving. The user's commands are recognized by the gaze recognizer which use a centroid of eye pupil and two reflection points extracted using a camera with infrared filter and two infrared LEDs. These are used to control the wheelchair through the user interface. Then wheelchair system detects the obstacles using 10 ultrasonic sensors and assists that it avoid collision with obstacles. The proposed intelligent wheelchair system consists of gaze recognizor, autonomous driving module, sensor control board and motor control board. The gaze recognizer cognize user's commands through user interface, then the wheelchair is controled by the motor control board using recognized commands. Thereafter obstacle information detected by ultrasonic sensors is transferred to the sensor control board, and this transferred to the autonomous driving module. In the autonomous driving module, the obstacles are detected. For generating commands to avoid these obstacles, there are transferred to the motor control board. The experimental results confirmed that the proposed system can improve the efficiency of obstacle avoidance and provide the convenient user interface to user.