• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.1
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• pp.16-23
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• 2000

A topography-precipitation relationship derived from the southern part of Korean Peninsula was applied to North Korea where climate stations are few and widely separated. Two hundred and seventy seven rain gauge stations of South Korea were classified into 8 different groups depending on the slope orientation (aspect) of the region they are located. Monthly precipitation averaged over 10 year period (1986-1995) was regressed to topographical variables of the station locations. A 'trend precipitation' for each gauge station was extracted from the precipitation surface interpolated from the monthly precipitation data of 24 standard stations of the Korea Meteorological Administration and used as a substitute for y-axis intercept of the regression equation. These regression models were applied to the corresponding regions of North Korea, which were identified by slope orientation, to obtain monthly precipitation surface for the aspect regions. 'Trend precipitation' from the 10 year data of 27 North Korean standard stations was also used in the model calculation. Output grids for each aspect region were mosaicked to form the monthly and annual precipitation surface with a 1km$\times$1km resolution for the entire territory of North Korea. Spatially averaged annual precipitation of North Korea was 938 mm with the standard deviation of 246 mm.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1024-1028
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• 1998

Crystalline structure of the extrudate of high amylose corn starch was studied by X-ray diffractometer and $^{13}C\;NMR$. The X-ray diffraction crystal ratio of the extrudates (barrel temperature $100^{\circ}C$ )of high amylose corn starch slightly increased from 6.08% to 8.37% by increasing feed moisture content from 25% to 45%. But extrudates of high amylose corn starch showed similar crystal ratio on various extrusion conditions. Extrudates of high amylose corn starch (feed moisture content 20%, barrel temp $140^{\circ}C$) showed more enlarged crystal structure than that of non-extrudates. The perpendicular distance of crystal increased by extrusion. Crystal ratio was changed from $6.3{\sim}8.3%$ to $4.5{\sim}5.8%$ during storage at $4^{\circ}C$. Starch configuration was examined with $^{13}C\;NMR$. Double helical content was measured by $^{13}C\;NMR$ method. The highest double helical content (60%) was obtained from high amylose corn starch extrudate (barrel temp.: $100^{\circ}C$, feed moisture content 45%). Double helical contents and resistant starch (RS) yield (pancreatin) were positively correlated. However, double helical content of the extrudates was not changed by the storage at $4^{\circ}C$.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.1
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• pp.6-12
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• 2010

Fiber optic sensor using fiber Bragg grating(FBG) probes is used for monitoring strain and temperature distributed on the wide surfaces of large structures. In this paper, in order to use many FBG probes in one optical fiber line, we propose a complex multiplexing technology which is composed of two techniques, one is time division multiplexing and another is wavelength division multiplexing. However, we only investigate the characteristics of time division multiplexing because FBG sensors basically can be operated by wavelength division multiplexing. We calculate the optimal reflectivities and the lengthwise location of five FBG probes in serial connection in order to obtain the unique reflected intensities from the FBG probes. We fabricate five FBG probes with the reflectivities of 13%, 16%, 25%, 40% and 80%, which are determined by the theoretical calculation, and observe the signal reflected from each FBG in the time domain from the experiment. There are differences between experimental and theoretical results caused by the signal noise and the differences of reflectivities of FBG probes. But the experimental results shows the reflected signals of five FBG probes which prove the availability of complex multiplexing.

• Journal of Korea Water Resources Association
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• v.49 no.2
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• pp.83-94
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• 2016

Geomorphological, bed material and hydraulic characteristics are basis informations for the planning, design and management of the river in the aspect of flood control and environmental conservation, and it is very important to use these informations for the design of stable channel. In this study, dominant discharge was selected, geomorphological and hydraulic characteristics were analyzed using that discharge and also the characteristics of bed materials distribution were analyzed and bed materials-flow resistance relationship was evaluated, for the upstream section of Namgang dam. The dominant discharge was estimated a return period of approximately 1.5 year and stream type were classified Segment 1 and Segment 2 in this stream. Also, the frequency of riffle-pool showed 4.4 because this study area has the characteristics of natural channel that have not channel-crossing structures. In dominant discharge, according to the results that analyzed relationship between $h/d_{50}$ and $V/u_*$ to calculate flow resistance by bed materials, Julian's formula showed to appropriate in channel where is relatively close to natural river and is predominantly consisted of gravel, cobble, boulder and rock in mountain, and it was confirmed that the image processing methodology will be easily applied to the analysis of bed materials distribution in future.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.4
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• pp.327-343
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• 2020

This study proposes a method to improve the geometric quality of KOMPSAT (Korea Multi-Purpose Satellite)-3/3A Level 1R imagery, particularly for efficient disaster damage analysis. The proposed method applies a novel grid-based SIFT (Scale Invariant Feature Transform) method to the Planetscope ortho-imagery, which solves the inherent limitations in acquiring appropriate optical satellite imagery over disaster areas, and the KOMPSAT-3/3A imagery to extract GCPs (Ground Control Points) required for the RPC (Rational Polynomial Coefficient) bias compensation. In order to validate its effectiveness, the proposed method was applied to the KOMPSAT-3 multispectral image of Gangnueng which includes the April 2019 wildfire, and the KOMPSAT-3A image of Daejeon, which was additionally selected in consideration of the diverse land cover types. The proposed method improved the geometric quality of KOMPSAT-3/3A images by reducing the positioning errors(RMSE: Root Mean Square Error) of the two images from 6.62 pixels to 1.25 pixels for KOMPSAT-3, and from 7.03 pixels to 1.66 pixels for KOMPSAT-3A. Through a visual comparison of the post-disaster KOMPSAT-3 ortho-image of Gangneung and the pre-disaster Planetscope ortho-image, the result showed appropriate geometric quality for wildfire damage analysis. This paper demonstrated the possibility of using Planetscope ortho-images as an alternative to obtain the GCPs for geometric calibration. Furthermore, the proposed method can be applied to various KOMPSAT-3/3A research studies where Planetscope ortho-images can be provided.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.67-72
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• 1992

The growth of Ti on Si(111)-$7{\times}7$ and the formation of epitaxial C54 $TiSi_2$ were investigated by using reflection high energy electron diffraction(RHEED) and high resolution transmission electron microscopy(HRTEM). Polycrystalline Ti layer is grown on the amorphous Ti-Si interlayer which is formed at the Ti/Si interface by Ti deposition on Si(111)-$7{\times}7$ at room temperature (RT). HRTEM lattice image and transmission electron diffraction(TED) showed that epitaxial C54 $TiSi_2$ grown on Si substrate with 160 ML of Ti on Si(111)-$7{\times}7$ surface at RT, followed by annealing at $750^{\circ}C$ for 10 min in UHV. Thin single crystal Si overlayer with [111] direction is grown on $TiSi_2$ surface when $TiSi_2$/Si(111) is annealed at ${\sim}900^{\circ}C$ in UHV, which was confirmed by Si(111)-$7{\times}7$ superstructure.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.161-162
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• 2011

최근 광전자 분야에서는 미래 에너지 자원에 대한 관심과 함께 GaN 기반 태양전지 연구가 활발히 진행되고 있다. GaN 물질은 높은 전자 이동도와 높은 포화 속도 등 광전자 소자에 유리한 광, 전기적 특성들을 가지고 있다. 또한, In의 함량을 변화시켜가며, 0.7eV에서 3.4eV까지 밴드갭을 조절함으로써, 자외선부터 적외선까지 태양빛 스펙트럼의 대부분을 흡수할 수 있는 장점이 있다. InGaN 태양전지의 효율을 높이기 위해서는 In의 함량을 늘려 밴드갭을 줄이는 것이 중요하다. 하지만 GaN 와 InN 간의 격자 부정합으로 인해 In 함량이 높은 단결정 InGaN 층을 두껍게 성장 하는 것이 어렵다. 때문에 GaN 기반 태양전지 관련 연구 그룹들이 태양전지의 효율 향상을 위해 활성층에 양자우물(MQWs) 구조, Supper Lattice (SLs) 구조와 같이 얇은 InGaN/GaN 층을 주기적으로 반복하여 적층함으로써 높은 조성의 In을 함유한 상질의 InGaN/GaN 층을 성장하는 연구들을 진행해 왔다. 본 연구에서는, p-i-n 구조와 MQW 구조를 갖는 InGaN 기반 태양전지를 제작하여, 각각의 특성을 분석해 봄으로써, In0.1Ga0.9N 태양전지 활성층의 구조에 따른 장/단점에 대해 논의하였다. 먼저 MOCVD를 이용하여 200 nm의 i-In0.1Ga0.9N 활성층을 갖는 p-i-n 구조와 In0.19Ga0.81N/GaN(3 nm/8 nm) MQWs (8 periods) 구조를 갖는 태양전지 에피를 각각 성장하였고, 그 후 공정을 통해 그림 1과 같이 InGaN 태양전지 소자를 제작하였다. 그 후, 각 태양전지의 전류/전압 곡선과 외부양자효율을 측정하여 그림 2와 같은 결과를 얻었다. p-i-n과 MQW 샘플의 외부양자효율은 각각 ~70%, ~25%로 측정 되었다. MQW 샘플의 외부 양자효율이 높지 않음에도 불구하고 p-i-n 구조에 비해 높은 In 함량을 가지고 있으므로, 더 넓은 파장의 빛을 흡수하여, 높은 단락전류(0.778 mA/cm2)를 보이고 있다. 또한 p-i-n 구조에 비해 높은 개방전압(2.3V)를 가지고 있으므로, MQW 샘플이 약 17% 정도 높은 변환효율(1.4%)를 보이고 있다. 이후 추가적으로 p-i-n 과 MQW 구조의 InGaN 태양전지에 나타나는 Voc와 Jsc의 차이를 Polarization 효과를 비롯한 다양한 측면에서 분석해 보고자 한다.

• Journal of the Mineralogical Society of Korea
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• v.16 no.4
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• pp.295-305
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• 2003

This study aims to provide the physicochemical properties of three kinds of organo­smectites which can be diversely used in industries. Some properties of them were compared with Na­smectite. Three kinds of organo­smectites such as Hexadecyltrimethylammonium(HDTMA), Benzyldimethyltetradecylammonium(BDTDA), and Cetylpyridinium(CP) exchanged smectites were manufactured for this study. Three types of organo­smectites showed the alkaline character(pH 9), very low swelling property and viscosity, and a fast flocculation behavior because of strong hydrophobic property in contrast to hydrophilic Na­smectite. Three organo­smectites showed the strong interlayer expansion with basal spacing from $19\AA$ to $23\AA$ compared with the Na­smectite of about 12 $\AA$. Organic cations such as HDTMA, BDTDA, and CP exchanged into smectite were completely decomposed in the temperature range from $250^{\circ}C$ to $400^{\circ}C$. Generally, three organo­smectites showed the similar mineralogical, physicochemical and thermal properties. But their properties are quite different from Na­smectite. Considering economically, CP exchanged smectite would be used for the diverse utilization field in the future time.

• Journal of Sensor Science and Technology
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• v.4 no.1
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• pp.51-63
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• 1995

Polycrystalline $CdS_{1-x}Se_{x}$ thin films were grown on ceramic substrate using a chemical bath deposition method. They were annealed at various temperature and X-ray diffraction patterns were measured by X-ray diffractometer in order to study $CdS_{1-x}Se_{x}$ polycrystal structure using extrapolation method of X-ray diffraction patterns for the CdS, CdSe samples annealed in $N_{2}$ gas at $550^{\circ}C$ it was found hexagonal structure which had the lattice constant $a_{0}=4.1364{\AA}$, $c_{0}=6.7129{\AA}$ in CdS and $a_{0}=4.3021{\AA}$, $c_{0}=7.0142{\AA}$ in CdSe, respectively. Hall effect on these samples was measured by Van der Pauw method and then studied on carrier density and mobility depending on temperature. We measured also spectral response, sensitivity(${\gamma}$), maximum allowable power dissipation and response time on these samples.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.2
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• pp.217-222
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• 2010

The geoid is the level surface that closely approximates mean sea level and usually used for the origin of vertical datum. For the computation of geoid, various sources of gravity measurements are used in South Korea and, as a consequence, the geoid models may show different results. however, a limited analysis has been performed due to a lack of controlled data, namely the GPS/Leveling data. Therefore, in this study, the gravimetric geoids are compared with the geodetic geoid which is obtained through the GPS/Leveling procedures. The gravimetric geoids are categorized into geoid from airborne gravimetry, geoid from the terrestrial gravimetry, NGII geoid(geoids published by National Geographic Information Institute) and NORI geoid(geoi published by National Oceanographic Research Institute), respectively. For the analysis, the geometric geoid is obtained at each unified national control point and the difference between geodetic and gravimetric geoid is computed. Also, the geoid height data is gridded on a regular $10{\times}10-km$ grid so that the FFT method can be applied to analyze the geoid height differences in frequency domain. The results show that no significant differences in standard deviation are observed when the geoids from the airborne and terrestrial gravimetry are compared with the geomertric geoid while relatively large difference are shown when NGII geoid and NORI geoid are compared with geometric geoid. Also, NGII geoid and NORI geoid are analyzed in frequency domain and the deviations occurs in long-wavelength domain.