• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.2
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• pp.120-131
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• 2009

This study measured the centripetal force and effective scope of the population spread from urban center and subcenters in order to diagnose the urban spatial structure of the formation of a multicentric city structure in Busan. The study analyzed the variability of the determination coefficient value (R square) with a negative exponential function derived from the population density model by extending the circular region into 5-km units. The aim of this study was to measure changes in the effective scope of the population centripetal force of the urban center and subcenter in 5-year intervals from 1995 to 2005 using census data. The explanatory adequacy of the population density function was examined with the bias of the function to calculate the distance error between the real location of the urban center and the optimal location, according to the population density function. To summarize the results, the value for the area of Jungangdong showed a continuous reduction, whereas Seomyeon (Bujeondong) maintained explanatory adequacy without a large change. As a whole, Busan was in the process of continuous diversification, in spite of its reduced population. Therefore, it appears necessary to strengthen the function of the urban center and subcenter and to supply adequate dwelling zones close to downtown to form a more efficient urban spatial structure. The results of the present study will be utilized as basic data for the formulation of a political approach to the efficient reorganization of spatial structure by correlating concrete spatial information with the population variability of Busan's urban center and subcenter.

• Korean Journal of Remote Sensing
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• v.36 no.5_3
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• pp.1013-1025
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• 2020

Unmanned Aerial Vehicle (UAV) platform is being widely used in disaster monitoring and smart city, having the advantage of being able to quickly acquire images in small areas at a low cost. Ground Control Points (GCPs) for positioning UAV images are essential to acquire cm-level accuracy when producing UAV-based orthoimages and Digital Surface Model (DSM). However, the on-site acquisition of GCPs takes considerable manpower and time. This research aims to provide an efficient and accurate way to replace the on-site GNSS surveying with three different sources of geospatial data. The three geospatial data used in this study is as follows; 1) 25 cm aerial orthoimages, and Digital Elevation Model (DEM) based on 1:1000 digital topographic map, 2) point cloud data acquired by Mobile Mapping System (MMS), and 3) hybrid point cloud data created by merging MMS data with UAV data. For each dataset a three-dimensional positional accuracy analysis of UAV-based orthoimage and DSM was performed by comparing differences in three-dimensional coordinates of independent check point obtained with those of the RTK-GNSS survey. The result shows the third case, in which MMS data and UAV data combined, to be the most accurate, showing an RMSE accuracy of 8.9 cm in horizontal and 24.5 cm in vertical, respectively. In addition, it has been shown that the distribution of geospatial GCPs has more sensitive on the vertical accuracy than on horizontal accuracy.

• Radiation Oncology Journal
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• v.10 no.2
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• pp.137-145
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• 1992

Three-dimensional dose calculations based on CT images are fundamental to stereotactic radiosurgery for small intracranial tumor. In our stereotactic radiosurgery program, irradiations have been performed using the 6 MV photon beam of linear accelerator after stereotactic CT investigations of the target center through the beam's-eye view and the coordinates of BRW frame converted to that of radiosurgery. Also we can describe the tumor diameter and the shape in three dimensional configuration. Non-coplanar irradiation technique was developed that it consists of a combination of a moving field with a gantry angle of $140^{\circ}$, and a horizontal couch angle of $200^{\circ}C$ around the isocenter. In this radiosurgery technique, we provide the patient head setup in the base-ring holder and rotate around body axis. The total gantry moving range shows angle of 2520 degrees via two different types of gantry movement in a plane perpendicular to the axis of patient. The 3-D isodose curves overlapped to the tumor contours in screen and analytic dose profiles in calculation area were provided to calculate the thickness of $80\%$ of tumor center dose to $20\%$ of that. Furtheremore we provided the 3-D dose profiles in entire calculation plane. In this experiments, measured isodose curves in phantom irradiation have shown very similiar to that of computer generations.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.179-179
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• 2000

음극의 크기에 따라 발생된 전자빔 전류가 도파관 영역에서 공간 전하 한계 전류를 초과할 경우 형성되는 가상 음극 (Virtual Cathode)을 이용한 축 방향으로의 고출력 마이크로파 발생 및 진단에 관한 연구를 수행하였다. 먼저 실험에 앞서 전산모사를 통해 결과를 예측하고 실험을 통해 확인하는 순으로 하였다. 전산 모사는 2-1/2차원 Partical-In-Cell(PIC) 코드인 "MAGIC"을 사용하여 축 방향으로 진행하는 새로운 개념의 가상 음극발진기를 모사하고, 정확한 경과를 얻기 위해 강렬한 상대론적 전자빔 발생 장치인 "천둥"( 최대 전압 600kV, 최대 전류 70KA, 60ns)을 사용하여 전산 모사에 넣어줄 전류값을 얻었다. 음극의 반지름이 2.5cm 일 때 전파되는 최대 출력이 약 800MW인 마이크로파가 발생되었고, 이때 출력변환 효율이 약 30%임을 전산모사를 통하여 알 수 있었다. 또한 전파하는 전기장의 축방향 성분(Ez)의 반지름 방향에 대한 분포 특성을 통하여 주된 전파 모드가 TM01와 그 상위모드의 조합으로 이루어졌음을 알았고 이때 기대되는 동작 진동수는 5~7 GHz임을 전산 모사 결과로부터 알 수 있었다. 실험을 통해서도 음극의 크기가 2.5cm 때, 최대 출력이 약 520MW인 마이크로파를 발생하였고, 이 때 출력 변환 효율은 약 8%이고, 방전 사진을 통해서 주된 동작 모드가 TM01와 그 상위모드의 조합으로 이루어졌음을 알았고, 이때 주된 출력 진동수는 5~6 GHz임을 알 수 있었다.는 5~6 GHz임을 알 수 있었다.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.15-24
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• 2001

In order to achieve a desirable tooth movement, it is of great importance to control the M/F ratio and to know the location of the center of resistance. The purpose of this study was to locate the center of resistance and the axis of rotation, and to estimate the stress distribution in the periodontal ligament with experimental model. After preparing a model of an upper canine with a simulated periodontal ligament and alveolar bone, the force and moment were applied. The tooth movement was traced using measuring device with LVDTs(Linear variable differential transformers) that can measure three dimensional tooth movement in real time. The results were as follows. 1. The location of center of resistance by transverse force was $29\%$ of root length measured from alveolar crest to apex regardless of force magnitude. The position of the center of resistance is more coronal than that of two-dimensional model($42\%$). 2. The center of resistance and the axis of rotation coincide when couple moment was applied. 3. As the magnitude of moment increases, tooth tends to extrude irrespective of the direction of the moment. 4. The relationship between location of force and axis of rotation (a x b = $49.6\;mm^2$) was obtained. A tooth movement can be predicted through this formula. 5. The centers of rotation by transverse force were plotted linearly.

• Economic and Environmental Geology
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• v.36 no.4
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• pp.305-312
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• 2003

This study was performed to delineate the subsurface geology, geologic structure, and distribution pattern of the Palgongsan granitic body, and to reveal the relationship between the Kyeongsang basin and Yongnam massif by gravity survey. The study area is located between the latitude of 35$^{\circ}$45'-36$^{\circ}$21'N and longitude of 128$^{\circ}$15'-129$^{\circ}$00'E. Total of 966 gravity data measured by Seoul National University, KlGAM(Korea Institute of Geology, Mining ＆ Materials), Pusan National University and Yonsei University were used. The Bouguer gravity anomaly in the study area ranges from -12.88 to 26.01 mgal with a mean value of 11.27 mgal. A very low anomaly zone is located in the Yongnam massif in west of the study area. The anomaly value increases going from west to east. A low anomaly distribution in Palgongsan granite and Yongnam massif is interpreted as the effect of their lower density than that of Kyeongsang Super Group. Power spectrum analysis is applied to evaluate the average depth of basement the Kyeongsang Basin and Conrad discontinuity from gravity anomaly. The average depths of density discontinuities are calculated 10.45 km and 4.9 km, and these are interpreted as Conrad discontinuity and depth of basement of the Kyeongsang Basin, respectively. The depth of Palgongsan granite is derived by means of 2-dimensional modeling and it decreases gradually toward the east. The gravity anomaly east of the study area decreases abruptly due to Shingryeong fault and Nogosan ring fault. Two deepest and sharp roots of Palgongsan granite are recognized by 2-dimensional modeling of each profiles. The depths of those roots are 5.3 km on a profile AA' and 7 km on a profile BB' which is the maximum depth of Palgongsan granite. Small granitic bodies are also seen to be intruded around the Palgongsan granite. The root of Palgongsan granite is shown by 3-dimensional analysis based on the interpolation of 2-dimensional modeling along each profiles to exist in the southwest vicinity of Palgongsan granite. The total volume of Palgongsan granite is approximately 31.211 $Km^3$.

• The Journal of the Acoustical Society of Korea
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• v.20 no.5
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• pp.76-82
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• 2001

Because the biological tissue with inhomogeneous acoustic properties does not keep a particular shape, the measurement of propagation characteristics of ultrasonic fields by the conventional scanning method with a miniature hydrophone is difficult. In this study, a two-dimensional may hydrophone was fabricated using the PVDF (Polyvinylidene fluoride) piezo-electric film and a ultrasonic field measurement system with it was established. For the acoustic field produced by a circular plan transducer with center frequency of 2.25㎒ and 13㎜ in diameter, it was possible to make a fairly accurate field measurement using the hydrophone system. The attenuation coefficients at 2.25 ㎒ for biological tissues were 0.7∼1.3 dB/cm(average; 1.0 dB/cm) in bovine liver, 1.0∼1.8 dB/cm (average; 1.6 dB/cm) in pig liver, 0.9∼2,9 dB/cm(average: 2.1 dB/cm) in bovine muscles, 1.7∼3.3 dB/cm (average; 2.5 dB/cm) in pig muscles.

• Journal of Animal Environmental Science
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• v.7 no.3
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• pp.147-154
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• 2001

An experiment was conducted to examine environmental influences upon the behavioral pattern of pigs. The resting areas of an enclosed growing-finishing pig house were checked in two seasonal ventilation systems, and the excretion habit of pigs influenced by the different closing rates (50, 75 and 100%) of side walls of pens was surveyed. 1. The excretion habit of pigs was not influenced by temperature, humidity and the flow speed of running air as they excreted in a fixed area of the side walls. However, the lighting effects on the excretion habit was observed because pigs excreted in the darkest area of the pig pen. 2. The accumulated height and width of feces showed 10 and 30 cm; 5 and 25cm; and 3 and 20cm for 50, 75 and 100% of closing rates of side walls, respectively. It indicates that pigs excrete all over the floor in the pen with 100% closed side walls. 3. Ammonia concentrations of the resting areas on the pen floor were determined to 4.2, 5.1 and $5.8mg/{\ell}$ for 50, 75 and 100% of closing rates of side walls, respectively. It indicates that the ammonia concentration was highest in the pen with 100% closed side walls. Thus, the high ammonia concentration of the resting areas could be reduced by illuminating the darker areas with relation to the excretion habit. 4. The flow speed of running air was likely the biggest factor influencing the resting areas of pigs; pigs took a rest at the place of 0.04 m/s air flow speed point during midwinter, and at the place of 0.24 m/s air flow speed point during midsummer.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.453-453
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• 2018

2017년 12월 기준 우리나라에 등록된 자동차는 약 2,200만 이상으로, 그 증가율은 매년 증가하는 추세이다. 이러한 최근 차량대수 및 고자산인 외산차 보유율 증가는 자연재난에서 노출과 관련한 위험도를 증가시키는 주요인이 되며, 홍수발생 시 상당한 규모의 경제적 피해를 야기한다. 현재 국가연구개발사업으로 진행 중인 행정안전부(2017) 연구는 위험지역 내 차량의 공간적 분포와 차량유형별 침수심에 따른 취약성을 고려하여 어떠한 홍수사상으로부터 예상되는 차량 피해액을 추정하는 방법을 제시한 바 있다. 여기서는 어떠한 집계구 내에서 동일한 침수심 구간을 가지는 면(polygon)을 분석단위로 하고 있는 데, 이를 편의성 차원에서 벡터자료에 기반 한 연산과정을 수행할 경우 정의된 침수구역도(재해정보)의 고유 정보가 훼손되거나, 세분화된 침수심 구간에 따른 손상률 관계를 사용할 수 없는 문제점이 있다. 이에 본 연구에서는 격자 기반의 침수구역도와 인벤토리 지도로부터 Raster GIS 공간연산을 활용한 차량피해 산정절차를 제시하였고, 이를 신천수계 하천기본계획(경기도, 2011)에서 계획된 치수사업에 적용하여 홍수빈도별 사업시행 전후 상황에 적용하였다. 이 과정에서 침수구역도는 인벤토리 상의 집계구 면적을 고려하여 $5m{\times}5m$ 크기로 제작하였고, 동일한 격자크기로 변환된 인벤토리는 변환 전후 면적을 기준으로 할 때 거의 오차가 없는 것으로 확인되었다. 그리고 Raster 공간연산으로부터 침수편입률을 결정하는 과정에서 집계구 넘버 및 침수심 정보를 확인하기 위한 자료별 전처리 과정을 제시하였고, 여기서 집계구 넘버는 인벤토리 정보와 침수심 정보는 손상함수와 연계된다. 본 연구에서 제시한 결과는 향후 실무에서 직접 적용하는 데 활용하기 위하여 방법론과 함께 가이드라인 문서로 정리할 계획이다.

• Journal of the Korean earth science society
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• v.32 no.6
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• pp.548-559
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• 2011

3-D Multi-geophysical surveys were carried out around the Hwasan caldera at the Euisung Sub-basin. To overcome the limitations of resolutions in previous studies, dense gravity data and magnetotelluric (MT) data were obtained and analyzed. In this study, the independent inversion models from gravity and MT data were integrated using correlation and classification approaches for 3-D imaging of the geologic structures. A Structure Index (SI) method was proposed and applied to the integration and classification analyses. This method consists of Type Angle (TA) and Type Intensity (TI) values, which are estimated by the spatial correlation and abnormality of the physical properties. The SI method allowed the classification analysis to be effectively performed. Major findings are as follows: 1) pyroclastic rocks around the central area of the Hwasan caldera with lower density and resistivity than those of neighboring regions extended to a depth of around 1 km, 2) intrusive igneous rocks with high resistivity and density were imaged around the ring fault boundary, and 3) a basement structure with low resistivity and high density, at a depth of 3-5 km, was inferred by the SI analysis.