• 대한지리학회지
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• 제43권3호
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• pp.324-336
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• 2008

본 연구에서는 최근의 한반도 여름철 강수특성을 파악하기 위해 장기간($1958{\sim}2007$년) 관측을 수행하고 있는 기상관측소를 대상으로 강수량의 변화 경향을 시 공간적으로 분석하였다. 여름철($6{\sim}9$월) 강수량의 연변화를 분석하고 여름철을 장마와 장마 후 강수기간으로 구분하여 그 특징을 살펴보았다. 장마기간에는 남서풍과 준정체전선의 영향으로 산악지역의 풍상측에서 최대 강수량이 발생하였으며 장마 후 강수기간에는 한반도 주변의 서쪽 및 남동쪽에서 유입되는 하층순환장과 함께 태풍, 대류불안정, 저기압성 강수에 의해 주로 남해안과 영동 산간 및 해안지방에서 최대 강수량이 나타났다. 여름철($6{\sim}9$월) 강수량의 시계열 변화에서는 모든 지점에서 강수량이 증가하는 경향을 보여주었으며 이 중에서도 최근 10년이 가장 큰 증가 경향을 보였다. 일 강수량을 10년 단위로 평균하여 분석한 결과, 모든 지점에서 최근 10년에 장마 및 장마 후 강수기간의 강수량이 가장 크게 증가하는 것으로 나타났다. 지점별로 증가 경향은 차이를 보여주었는데, 강릉은 장마 후 강수기간의 강수량이 장마기간보다 더 많았으며 최근 들어 장마 후 강수기간의 강수량이 가장 크게 증가하였다. 서울과 부산의 경우는 최근 10년 동안 여름철 강수량의 두 개 최대값 사이의 강수량이 크게 증가하는 경향을 보여주었다.

• 한국레이저가공학회지
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• 제16권4호
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• pp.1-6
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• 2013

Femtosecond laser patterning of ITO on a touch screen panel with a shaped fs laser beam was investigated. A quasi flat-top beam was formed using a variable mask and a planoconvex lens. The spatial profile of the original Gaussian beam and the shaped beam were monitored by a CCD beam profiler. The laser patterned ITO film was examined using an optical microscope, Scanning Electron Microscope (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), and Atomic Force Microscope (AFM). It turned out that the quality of the ITO pattern fabricated by a shaped beam is superior to that of the pattern without beam shaping in terms of debris generation, height of the craters, and homogeneity of the bottom. Optimum processing window was determined at the laser irradiance exhibiting 100% removal of Sn. The removal rate of In was measured to be 83%.

• 대기
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• 제20권4호
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• pp.415-426
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• 2010

A Land cover map over East Asian region (Kongju national university Land Cover map: KLC) is classified by using support vector machine (SVM) and evaluated with ground truth data. The basic input data are the recent three years (2006-2008) of MODIS (MODerate Imaging Spectriradiometer) NDVI (normalized difference vegetation index) data. The spatial resolution and temporal frequency of MODIS NDVI are 1km and 16 days, respectively. To minimize the number of cloud contaminated pixels in the MODIS NDVI data, the maximum value composite is applied to the 16 days data. And correction of cloud contaminated pixels based on the spatiotemporal continuity assumption are applied to the monthly NDVI data. To reduce the dataset and improve the classification quality, 9 phenological data, such as, NDVI maximum, amplitude, average, and others, derived from the corrected monthly NDVI data. The 3 types of land cover maps (International Geosphere Biosphere Programme: IGBP, University of Maryland: UMd, and MODIS) were used to build up a "quasi" ground truth data set, which were composed of pixels where the three land cover maps classified as the same land cover type. The classification results show that the fractions of broadleaf trees and grasslands are greater, but those of the croplands and needleleaf trees are smaller compared to those of the IGBP or UMd. The validation results using in-situ observation database show that the percentages of pixels in agreement with the observations are 80%, 77%, 63%, 57% in MODIS, KLC, IGBP, UMd land cover data, respectively. The significant differences in land cover types among the MODIS, IGBP, UMd and KLC are mainly occurred at the southern China and Manchuria, where most of pixels are contaminated by cloud and snow during summer and winter, respectively. It shows that the quality of raw data is one of the most important factors in land cover classification.

• Journal of Astronomy and Space Sciences
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• 제35권3호
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• pp.195-200
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• 2018

The present paper describes the design of a Solid State Telescope (SST) on board the Korea Astronomy and Space Science Institute satellite-1 (KASISat-1) consisting of four [TBD] nanosatellites. The SST will measure these radiation belt electrons from a low-Earth polar orbit satellite to study mechanisms related to the spatial resolution of electron precipitation, such as electron microbursts, and those related to the measurement of energy dispersion with a high temporal resolution in the sub-auroral regions. We performed a simulation to determine the sensor design of the SST using GEometry ANd Tracking 4 (GEANT4) simulations and the Bethe formula. The simulation was performed in the range of 100 ~ 400 keV considering that the electron, which is to be detected in the space environment. The SST is based on a silicon barrier detector and consists of two telescopes mounted on a satellite to observe the electrons moving along the geomagnetic field (pitch angle $0^{\circ}$) and the quasi-trapped electrons (pitch angle $90^{\circ}$) during observations. We determined the telescope design of the SST in view of previous measurements and the geometrical factor in the cylindrical geometry of Sullivan (1971). With a high spectral resolution of 16 channels over the 100 keV ~ 400 keV energy range, together with the pitch angle information, the designed SST will answer questions regarding the occurrence of microbursts and the interaction with energetic particles. The KASISat-1 is expected to be launched in the latter half of 2020.

• 한국항공우주학회지
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• 제33권2호
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• pp.11-21
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• 2005

3차원 비정렬 격자를 이용한 로터-동체 공력 상호작용에 대한 수치적 해석을 수행하였다. 로터와 동체간의 상대적인 운동을 모사하기 위하여 해석 유동장을 회전하는 부분과 정지된 부분으로 나누어 계산하였다. 블레이드 끝단에서 생성되는 끝단 와류를 포착하기 위하여 준 비정상 적응 격자 기법을 도입하였다. 또한 낮은 속도로 전진 비행하는 헬리콥터 해석을 위해서 저 마하수 예조건화 기법을 적용하였다. 로터-동체 공력 간섭현상에 대한 검증을 위해 Georgia Tech 형상과 NASA에서 실험한 ROBIN 형상에 대한 실험 결과와 비교하여 본 연구 해석 기법이 타당함을 보였다.

• Journal of the Optical Society of Korea
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• 제16권2호
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• pp.141-144
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• 2012

A mobile Rayleigh Doppler wind LIDAR at an eye-safe wavelength of 355 nm incorporating double-edge technique with triple-channel Fabry-Perot etalon is developed for wind measurement from 5 to 40km. The structure of this LIDAR system is described. An intercomparsion experiment with rawinsonde is made, showing good agreement with expected measurement accuracy. A continuous observation of stratosphere wind field for several days with temporal resolution of 15 min and spatial resolution of 200 m from 5 to 40 km is presented, demonstrating the stability and robustness of the LIDAR. A stratospheric quasi-zero wind layer can be found at around 20 km with a direction change from east to west evident in the continuous observation.

• 한국지리정보학회지
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• 제6권3호
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• pp.139-150
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• 2003

한국 연근해역의 중규모 해양 환경변동이 Cochlodinium polykrikoides 적조의 시공간 분포 변동과 밀접한 관련성이 있는 것으로 나타났다. 매년 하계 한국 연안역에서 적조가 최초로 발생한 전남 고흥 나로도 연안의 해양환경 상태는 최근 7년(1995~2001) 동안 열염전선대에 위치하였다. 대규모 적조발생은 7년 동안 매 홀수해(1995, 1997, 1999, 2001)에 나타났는데 동중국해 북부해역에서 표면 수온 및 염분의 큰 변동 또한 격년 주기로 나타났다. 저온 고염(홀수해), 고온 저염(짝수해)의 중규모적 해황 변동에 따라 적조의 공간분포 규모가 크게 변동되는 것으로 추정되었다. 한편, 동해연안으로 유입 확산되는 C. polykrikoides 적조의 분포와 이동상황은 동해남부 연안에서 발생하는 냉수대의 시공간 변동 규모에 따라 다르게 나타났다.

• 한국BIM학회 논문집
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• 제10권4호
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• pp.1-10
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• 2020

While the importance of barrier-free and fire evacuation design is highlighted in architectural design education, systemic analysis, and examination on such performances are still challenging due to methodological lacks. The present study investigates the effectiveness of BIM-based human behavior simulation for architecture major students' analytical examinations to promote barrier-free and fire evacuation performances. To achieve such an aim, quasi-experiments were conducted, which compare 50 students' analysis and examination scores according to the use and non-use of the simulation, and the data were collected via participants' survey and interview. As a result, T-Test and MANOVA analyses indicate that, compared with its non-use counterpart, the use of human behavior simulation better facilitates the students' (1) examination of the physical properties and dimensions for the disabled's accessibility and evacuation, (2) understanding of the bodily capacity and handicap of the disabled, (3) examination on the spatial layouts and locations of exits, (4) understanding on evacuees' urgent behaviors, and (5) responsibility as an architect. Based on previous studies, the reasons of statistical results are interpreted as the explicit observation and analytical measures of multiple numbers of virtual-evacuees and direct-experience from body range of the disabled responding to the populated occupants as what they face in authentic reality.

• Steel and Composite Structures
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• 제43권2호
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• pp.139-152
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• 2022

Steel-reinforced concrete (SRC) L-shaped column is the vertical load-bearing member with high spatial adaptability. The seismic behavior of SRC L-shaped column is complex because of their irregular cross sections. In this study, the hysteretic performance of six steel truss reinforced concrete L-shaped columns specimens under the combined loading of compression, bending, shear, and torsion was tested. There were two parameters, i.e., the moment ratio of torsion to bending (γ) and the aspect ratio (column length-to-depth ratio (φ)). The failure process, torsion-displacement hysteresis curves, and bending-displacement hysteresis curves of specimens were obtained, and the failure patterns, hysteresis curves, rigidity degradation, ductility, and energy dissipation were analyzed. The experimental research indicates that the failure mode of the specimen changes from bending failure to bending-shear failure and finally bending-torsion failure with the increase of γ. The torsion-displacement hysteresis curves were pinched in the middle, formed a slip platform, and the phenomenon of "load drop" occurred after the peak load. The bending-displacement hysteresis curves were plump, which shows that the bending capacity of the specimen is better than torsion capacity. The results show that the steel truss reinforced concrete L-shaped columns have good collapse resistance, and the ultimate interstory drift ratio more than that of the Chinese Code of Seismic Design of Building (GB50011-2014), which is sufficient. The average value of displacement ductility coefficient is larger than rotation angle ductility coefficient, indicating that the specimen has a better bending deformation resistance. The specimen that has a more regular section with a small φ has better potential to bear bending moment and torsion evenly and consume more energy under a combined action.

• 천문학회보
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• 제45권1호
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• pp.43.1-43.1
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• 2020

Cassiopeia A (Cas A) is a young supernova remnant (SNR) where we observe the interaction of SNR blast wave with circumstellar medium. From the early optical studies, dense, slowly-moving, N-rich "quasi-stationary flocculi" (QSF) have been known. These are probably dense CNO-processed circumstellar knots that have been engulfed by the SNR blast wave. We have carried out near-infrared, high-resolution (R=45,000) spectroscopic observations of ~40 QSF, and here we present the result on a QSF knot (hereafter 'Knot 24') near the SNR boundary of Cas A. The average [Fe II] 1.644 um spectrum of Knot 24 has a remarkable shape with a narrow (~8 km/s) line superposed on the broad (~200 km/s) line emitted from shocked gas. The spatial morphology and the line parameters indicate that Knot 24 has been partially destroyed by a shock wave and that the narrow line is emitted from the unshocked material heated/ionized by the shock radiation. This is the first detection of the emission from the pristine circumstellar material of the Cas A supernova progenitor. We also detected H Br gamma and other [Fe II] lines corresponding to the narrow [Fe II] 1.644 um line. For the main clump where we can clearly identify the shock emission associated with the unshocked material, we analyze the observed line ratios using a shock model that includes radiative precursor. The analysis indicates that the majority of Fe in the unshocked material is in the gas phase, not depleted onto dust grains as in the general interstellar medium. We discuss the non-depletion of Fe in QSF and its implications on the immediate progenitor of the Cas A supernova.