• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1227-1229
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• 2003

Kojima Lake in Okayama prefecture is a freshing reservoir constructed adjacent to the oldest reclaimed land in Japan. This lake has a serious water quality problem because two urban rivers are flowing into it. In the present study, unsupervised classification was performed at intervals of several years using Landsat MSS data in the past 15 years. After geometric correction of these data, MSS data corresponding geographically to the field observation data were extracted and subjected to the multivariate analysis. Water quality distribution in the lake was estimated using the regression equation obtained as a result. In addition, two - dimensional and three-dimensional numerical simulations were performed and compared with the distribution obtained from the satellite images. Behavior of the reservoir flows is complicated and water quality distribution varies greatly with the flows. Here, I report the results of analysis on three factors, field observation, numerical simulation and satellite images.

• 대기
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• 제30권2호
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• pp.169-181
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• 2020

We conducted a study on the impact of observation station density; this was done in order to enable the accurate estimation of spatial meteorological variables. The purpose of this study is to help operate an efficient observation network by examining distributions of temperature, relative humidity, and wind speed in a test area of a three-dimensional meteorological observation project in the Yeongdong region in 2019. For our analysis, we grouped the observation stations as follows: 41 stations (for Step 4), 34 stations (for Step 3), 17 stations (for Step 2), and 10 stations (for Step 1). Grid values were interpolated using the kriging method. We compared the spatial accuracy of the estimated meteorological grid by using station density. The effect of increased observation network density varied and was dependent on meteorological variables and weather conditions. The temperature is sufficient for the current weather observation network (featuring an average distance about 9.30 km between stations), and the relative humidity is sufficient when the average distance between stations is about 5.04 km. However, it is recommended that all observation networks, with an average distance of approximately 4.59 km between stations, be utilized for monitoring wind speed. In addition, this also enables the operation of an effective observation network through the classification of outliers.

• 대한토목학회논문집
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• 제7권2호
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• pp.89-98
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• 1987

X-Ray 사진측량(寫眞測量)은 인체에 대한 해부학적(解剖學的) 또는 생리학적(生理學的) 자료를 사진형태로 기록하여 해석하는 방법이다. 본 연구는 X-Ray를 이용하여 모델이 되는 피사체(被寫體)에 변형(變形)을 준 각 경우와, 인체 부분을 모델로 할 경우의 3 차원 좌표에 대한 정확도를 분석하므로써, X-Ray 사진(寫眞)에 의한 3 차원 위치결정의 정확도(正確度)를 향상시키고, 실용성을 높이는데 그 목적을 두고 있다. X-Ray를 이용하여 인체부분의 실제 피사체(被寫體)를 관측(觀測)한 결과, 높은 정확도(正確度)로 실제응용을 할 수 있었으며, X-Ray 사진을 이용하여 피사체(被寫體) 모든 면에 대한 삼차원(三次元) 좌표(座標)를 결정 할 수 있었다.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1697-1704
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• 2018

As a key component of lighting location system (LLS) for lightning warning, the atmospheric electric field measuring is required to have high accuracy. The Conventional methods of the existent electric field measurement meter can only detect the vertical component of the atmospheric electric field, which cannot acquire the realistic electric field in the thunderstorm. This paper proposed a three dimensional (3D) electric field system for atmospheric electric field measurement, which is capable of three orthogonal directions in X, Y, Z, measuring. By analyzing the relationship between the electric field and the relative permittivity of ground surface, the permittivity is calculated, and an efficiency 3D measurement model is derived. On this basis, a three-dimensional electric field sensor and a permittivity sensor are adopted to detect the spatial electric field. Moreover, the elevation and azimuth of the detected target are calculated, which reveal the location information of the target. Experimental results show that the proposed 3D electric field meter has satisfactory sensitivity to the three components of electric field. Additionally, several observation results in the fair and thunderstorm weather have been presented.

• 대기
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• 제26권3호
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• pp.423-433
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• 2016

In this study, performance of a computational fluid dynamics (CFD) model is assessed from analysis on air flow pattern which is observed in the artificial street canyon. Field observations focusing on flows were conducted at an artificial street canyon in Magok region. For the observation of three-dimensional airflow structures, twelve three-dimensional wind anemometers (hereafter, CSAT3) were installed inside the street canyon. The street canyon was composed of two rectangular buildings with 35-m length, 4-m width, and 7-m height. The street width (distance between the buildings) is 7 m, making the street aspect ratio (defined by the ratio of building height to street width) of 1. For the observation of above-building wind, a CSAT3 was installed above the northwest-side building. Southwesterly, westerly and northwesterly were dominant in the street canyon during the observations. Because wind direction is parallel to the street canyon in the southwesterly case, westerly and northwesterly were selected as inflow directions in numerical simulations using a computational fluid dynamics model developed through the collaborative research project between National Institute of Meteorological Sciences and Seoul National University (CFD_NIMR_SNU). The observations showed that a well-structured vortex flow (skimming flow) and an evidence of a small eddy at the corner of the downwind building and ground appeared. The CFD_NIMR_SNU reproduced both the observed flow patterns reasonably well, although wind speeds inside the street canyon were underestimated.

• 대기
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• 제31권4호
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• pp.405-420
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• 2021

Forest fire happens every year at Yeongdong, Gangwon-do, due to the strong local wind during the spring time and it causes a huge damage. This wind is named "Yangganjipung" or "Yanggangjipung" that blows along Yeongdong. However, the occurrence conditions of the wind have been still unclear. To identify the occurrence mechanism of local strong wind through three-dimensional observation data, Gangwon Regional Meteorological Administration performed Joint Gangwon-Yeongdong 3D Observation Project in 2020. The special observation was carried out for 6 times from March to April. The observation data was analyzed by focusing on the structure of synoptic pressure distribution and inversion layer. The result showed that the strength of wind is different depending on the latitude of low pressure, intensity of inversion layer, and changes on height in the south-high and north-low pressure distribution. As the interval of the upper and lower parts of the inversion layer was narrow, the strength of the wind became stronger, which is one of the observational characteristics of the springtime wind pattern at Yeongdong, Gangwon-do. In future, the clear mechanism of the local wind in the Yeongdong during the spring time is expected to be verified based on the accumulative observation data and close analysis.

• Steel and Composite Structures
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• 제12권2호
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• pp.93-115
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• 2012

This paper presents a numerical investigation of the mechanical behaviour of extended end - plate steel connections including comparison with full size experiments. Contact and friction laws have been taken into account with nonlinear, three dimensional finite element analysis. Material and geometric nonlinearities have been implemented to the model, as well. Results are then compared with experimental tests conducted at the Jordan University of Science and Technology. According to the most significant observation of the analysis, a separation of the column flange from the extended end - plate occurs. Other important structural parameters of the connection, like the impact of some column stiffeners on the overall response, local buckling of the column and friction of the beam to column interface, have been examined as well.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2010년 춘계학술발표회 논문집
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• pp.257-258
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• 2010

최근 넓은 지역에 대해 신속하게 3차원 위치좌표 데이터를 취득하기 위하여 항공레이저 스캐닝 시스템에 의해 취득된 데이터가 활용되고 있다. 현재 작업규정에 따르면 GPS 기준국과 항공기 GPS 거리가 반경 30km 이내로 정해져 있다. 본 연구에서는 항공라이다측량을 수행하는 데 있어 국토지리 정보원에서 운영중인 GPS상시관측소를 이용한 데이터와 비교하고자 한다.

• Structural Engineering and Mechanics
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• 제86권1호
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• pp.17-27
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• 2023

To investigate the mechanical behavior of the post-tensioned prestressed concrete lining (PPCL), the desilting tunnel of the Xiaolangdi Hydro Project in China is adopted as a case, and a detailed three-dimensional continuum model verified by the observation results is established for the PPCL. The radial stresses, longitudinal stresses, axial forces and bending moments of the PPCL under the completed cable tension condition (CCTC) and design water pressure condition (DWPC) are analyzed, respectively. The numerical results reveal that the PPCL concrete is significantly compressed in the circumferential direction by the prestress, while the prestress has a negligible influence on the radial stresses of the PPCL concrete. It should be noted that the concrete near the anchor slots has a complex and adverse stress state with stress concentration, longitudinal tensioning and large bending moment. In addition, a simplified shell model and a further simplified beam model which can take the influences of the prestress loss and the anchor slot into consideration are proposed for the PPCL. The results of the simplified models are in a good agreement with these of the three-dimensional continuum model, and they can be used as efficient approaches for the structural design and analysis of the PPCL.

• 한국가시화정보학회지
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• 제1권2호
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• pp.58-70
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• 2003

Meteorological data contains observation and numerical weather prediction model output data. The computerized analysis and visualization of meteorological data often requires very high computing capability due to the large size and complex structure of the data. Because the meteorological data is frequently formed in multi-variables, 3-dimensional and time-series form, it is very important to visualize and analyze the data in 3D spatial domain in order to get more understanding about the meteorological phenomena. In this research, we developed interactive 3-dimensional visualization techniques for visualizing meteorological data on a PC environment such as volume rendering, iso-surface rendering or stream line. The visualization techniques developed in this research are expected to be effectively used as basic technologies not only for deeper understanding and more exact prediction about meteorological environments but also for scientific and spatial data visualization research in any field from which three dimensional data comes out such as oceanography, earth science, and aeronautical engineering.