• Journal of Korea Spatial Information System Society
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• v.11 no.2
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• pp.133-142
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• 2009

Recently, with the advance of wireless internet and the frequent use of mobile devices, demand for LBS(Location Based Service) is increasing, and research is required on spatial indexes for the storage and maintenance of spatial data to provide efficient LBS in mobile device environments. In addition, the use of flash memory as an auxiliary storage device is increasing in order to store large spatial data in a mobile terminal with small storage space. However, the application of existing spatial indexes to flash-memory lowers index performance due to the frequent updates of nodes. To solve this problem, research is being conducted on flash-memory based spatial indexes, but the efficiency of such spatial indexes is lowered by low utilization of buffer and flash-memory space. Accordingly, in order to solve problems in existing flash-memory based spatial indexes, this paper proposed FR-Tree (Flash-Memory based R-Tree) that uses the node compression technique and the delayed write operation technique. The node compression technique of FR-Tree increased the utilization of flash-memory space by compressing MBR(Minimum Bounding Rectangle) of spatial data using relative coordinates and MBR size. And, the delayed write operation technique reduced the number of write operations in flash memory by storing spatial data in the buffer temporarily and reflecting them in flash memory at once instead of reflecting the insert, update and delete of spatial data in flash-memory for each operation. Especially, the utilization of buffer space was enhanced by preventing the redundant storage of the same spatial data in the buffer. Finally, we perform ed various performance evaluations and proved the superiority of FR-Tree to the existing spatial indexes.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.1
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• pp.1-7
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• 2023

An artificial intelligence (AI) method based on image deep learning is proposed to predict the entire displacement shape of a structure using the feature of partial displacements. The performance of the method was investigated through a structural test of a steel frame. An image-to-image regression (I2IR) training method was developed based on the U-Net layer for image recognition. In the I2IR method, the U-Net is modified to generate images of entire displacement shapes when images of partial displacement shapes of structures are input to the AI network. Furthermore, the training of displacements combined with the location feature was developed so that nodal displacement values with corresponding nodal coordinates could be used in AI training. The proposed training methods can consider correlations between nodal displacements in 3D space, and the accuracy of displacement predictions is improved compared with artificial neural network training methods. Displacements of the steel frame were predicted during the structural tests using the proposed methods and compared with 3D scanning data of displacement shapes. The results show that the proposed AI prediction properly follows the measured displacements using 3D scanning.

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.2
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• pp.159-165
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• 2013

Purpose: Abdominal compressor is used to control breathing in stereotactic body radiotherapy for lung tumors frequently. We evaluated the dynamic variation aspect of internal tumor volume by breathing. Materials and Methods: We reviewed 20 lung cancer patients (7 upper lung patients, 4 middle lung patients, 9 lower lung patients) who received stereotactic body radiotherapy using abdominal compressor between April 2012 to April 2013. Coordinate shift values were obtained by using four-dimensional cone-beam CT (4D-CBCT) to investigate treatment set-up error and moving tumor position error. To investigate how much difference of each part, we compared 95% confidence interval, maximum values and minimum values of three-dimensional vector value and analyzed conformity degree through the Pearson square correlation coefficient. Results: 95% confidence interval of three-dimensional vector value of each part is 1.8~2.9 mm in upper lobe, 2.3~5.4 mm in middle lobe and 2.2~4.0 mm in lower lobe. Conformity degree was the result that respectively is LR direction 0.75, SI direction 0.68 and AP direction 0.63 in upper lobe, LR direction 0.82, SI direction 0.51 and AP direction 0.92 in middle lobe and LR direction 0.63, SI direction 0.50 and AP direction 0.34 in lower lobe. Conclusion: We showed difference by each site in lung tumor due to respiration by using abdominal compressor. Therefore, we must correct treatment set-up error as well as moving tumor position error by breathing. It is also considered to be useful that it is the use of 4D-CBCT when correcting the error due to various dynamic variation.

• Progress in Medical Physics
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• v.20 no.1
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• pp.1-6
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• 2009

For HDR intracavitary brachytherapy with ovoids and a tandem, we compared the dose discrepancy of treatment plans using two different Ir-192 sources (microSelectron, Varian) and generated on two different treatment planning systems (PLATO, BrachyVision). The treatment plans of ten patient treated from Oct. 2007 to Jan. 2008 were selected for these comparisons. For the comparison of dose calculation using different sources, the average discrepancies were $-0.91{\pm}0.09%$, $-0.27{\pm}0.07%$, $0.22{\pm}0.39%$, and $0.88{\pm}0.37%$ in total treatment time and at B-point and ICRU bladder and rectum reference point, respectively. Comparing the two systems, the average dose discrepancies between treatment planning programs were $-0.22{\pm}0.42%$, $-0.25{\pm}0.29%$, $-0.23{\pm}0.63%$, and $-0.17{\pm}0.76%$, and the average dose discrepancies between positioning methods (PLATO with film and BrachyVision with digitial image) were $-0.61{\pm}0.59%$, $-0.77{\pm}0.45%$, $-0.72{\pm}1.70%$, and $0.35{\pm}2.82%$ at A-point, B-point, and ICRU bladder and rectum reference points, respectively. The rectal dose discrepancies between two systems were reached 5.87%. The difference in the dwell position expected by each TPS are mainly affected by the differences in the positioning method in TPSs and have an effect on dose calculations of rectal and bladder located in AP direction.

• The Journal of the Korea Contents Association
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• v.11 no.8
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• pp.51-58
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• 2011

This paper describes a development of system that enables the user to manage and display from 3D viewer after at real-time saves attribute informations in DBMS using RTK systems and 3D game engines. The 3-dimensional game engines for this system will be input a attribute values of underground utilities which is measured from RTK systems with wireless network. This system which sees does to make be a possibility of managing creation, elimination, modification for the underground utilities from 3-dimensional viewer. The coordinates about the underground utilities measures with GPS. The base reference point for RTK systems uses one in reference points which are measured in existing. GPS coordinates revised a reference point in standard. The 3-dimensional game engines are having the function which manages the underground utilities with 3-dimensions. The function is the same as wireless network of RTK systems, 3-dimensional display for terrain and underground utilities, input and registration for attribute of underground utilities, etc. The system which sees will be able to prevent the various accident which is caused by in the spatial location coordinate which underground utilities is inaccurate. And the system which sees is accurate is a possibility of managing and the application possibility is high very. Finally, this system could be applied very usefully from the point of view which starts a new town development.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1429-1433
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• 2010

수공구조물의 설계, 수자원 관리계획의 수립, 재해영향 검토 등을 수행할 때, 재현기간에 따른 확률개념의 강우량, 홍수량, 저수량 등을 산정하여 사용하게 되며, 보통 대상지역의 장기 수문관측 자료를 이용하여 수문사상의 확률분포를 산정한 후 재현기간을 연장하여 원하는 설계빈도에 해당하는 양을 추정하게 된다. 미계측지역 또는 관측자료의 보유기간이 짧은 지역의 경우는 지역빈도 분석 결과를 이용하게 된다. 지역빈도해석을 위해서는 강우자료들의 동질성을 파악하는 것이 가장 기본적인 과정이 되며 이를 위해 통계학적인 범주화분석이 선행되어야 한다. 지점 빈도분석의 수문학적 동질성 판별을 위해 L-moment 방법, K-means 방법에 의한 군집분석 등이 주로 사용되며 관측소 위치좌표를 이용한 공간보간법을 적용하여 시각화하고 있다. 강수량은 시공간적으로 변하는 수문변량으로서 강수량의 시간적인 특성 또한 강수량의 특성을 정의하는데 매우 중요한 요소이다. 이러한 점에서 본 연구를 통해 강수지점의 공간적인 좌표 및 강수량의 양적인 범주화에 초점을 맞춘 기존 지역빈도분석의 범주화 과정에 덧붙여 시간적인 영향을 고려할 수 있는 요소들을 결정하고 이를 활용할 수 있는 범주화 과정을 제시하고자 한다. 즉, 극치강수량의 발생 시기에 대한 정량적인 분석이 가능한 순환통계기법을 이용하여 관측 지점별 시간 통계량을 산정하고, 이를 극치강수량과 결합하여 시 공간적인 특성자료를 생성한 후 이를 이용한 군집화 해석 모형을 개발하는데 연구의 목적이 있다. 분석 과정에 있어서 시간속성의 정량화 및 일반화는 순환통계기법을 사용하였으며, 극치강수량과 발생시점의 속성자료는 각각의 평균과 표준편차를 이용하였다. K-means 알고리즘을 이용해 결합자료를 군집화 하고, L-moment 방법으로 지역화 결과에 대한 검증을 수행하였다. 속성 결합 자료의 군집화 효과는 모의데이터 실험을 통해 확인하였으며, 우리 나라의 58개 기상관측소 자료를 이용하여 분석을 수행하였다. 예비해석 단계에서 100회의 군집분석을 통해 평균적인 centroid를 산정하고, 해당 값을 본 해석의 초기 centroid로 지정하여, 변동적인 클러스터링 경향을 안정화시켜 해석이 반복됨에 따라 군집화 결과가 달라지는 오류를 방지하였다. 또한 K-means 방법으로 계산된 군집별 공간거리 합의 크기에 따라 군집번호를 부여함으로써 군집의 번호순서대로 물리적인 연관성이 인접하도록 설정하였으며, 군집간의 경계선을 추출할 때 발생할 수 있는 오류를 방지하였다. 지역빈도분석 결과는 3차원 Spline 기법으로 도시하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.205-212
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• 2018

In order to overcome shortcomings of commercial analysis program for solving certain geotechnical problems, finite element method adopting isoparametric quadrilateral element was selected as a tool for analyzing soil behavior and calculating process was programmed. Two examples were considered in order to verify reliability of the developed program. One of the two examples is the case of acting isotropic confining pressure on finite element and the other is the case of acting shear stress on the sides of the finite element. Isoparametric quadrilateral element was considered as the finite element and displacements in the element can be expressed by node displacements and shape functions in the considered element. Calculating process for determining strain which is defined by derivatives using global coordinates was coded using the Jacobian and the natural coordinates. Four point Gauss rule was adopted to convert double integral which defines stiffness of the element into numerical integration. As a result of executing analysis of the finite element under isotropic confining pressure, calculated stress corresponding to four Gauss points and center of the element were equal to the confining pressure. In addition, according to the analyzed results for the element under shear stress, horizontal stresses and vertical stresses were varied with positions in the element and the magnitudes and distribution pattern of the stresses were thought to be rational.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.2
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• pp.61-66
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• 2019

Augmented reality is a technology that makes a virtual object appear as if it exists in reality by composing a virtual object in real time with the image captured by the camera. In order to augment the virtual object on the object existing in reality, the homography of images utilized to estimate the position and orientation of the object. The homography can be estimated by applying the RANSAC algorithm to the feature points of the images. But the homography estimation method using the RANSAC algorithm has a problem that accurate homography can not be estimated when there are many feature points in the background. In this paper, we propose a method to filter feature points of a background when the object is near and the background is relatively far away. First, we classified the depth image into relatively near region and a distant region using the Otsu's method and improve homography estimation performance by filtering feature points on the relatively distant area. As a result of experiment, processing time is shortened 71.7% compared to a conventional homography estimation method, and the number of iterations of the RANSAC algorithm was reduced 69.4%, and Inlier rate was increased 16.9%.

• Korean Journal of Construction Engineering and Management
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• v.24 no.2
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• pp.13-23
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• 2023

Unlike building construction projects, where the activity is repeatedly carried out in a limited area, civil engineering projects such as roads and railroads are carried out in a linear type in a horizontal working space over several tens of kilometers. Each activity is managed with a station number that has a unit of distance from the starting point to the end point. For this reason, since the work location information of the activity is a major management factor, the Gantt chart system that expresses only schedule information may have limitations. In this study, authors propose a method for constructing a linear schedule chart that can simultaneously express schedule information indicating the start and finish dates and location information indicating the start and end positions of each activity, and develop a system for generating a linear schedule chart. In the study, the coordinate axes of the linear schedule chart consisted of distance and date values on the X and Y axes, respectively, and each activity was expressed as a symbol that can infer the type of work to increase the visibility of the linear schedule chart compared to the simple bar chart method. The linear schedule chart generation system was reviewed for practical applicability by utilizing the actual schedule data of bridge structures in a railroad project.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.379-386
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• 2010

This study evaluated the motion of tumors during the entire period of therapy and the accuracy of radiosurgery among forty eight lung tumor patients who were underwent radiosurgery using the CyberKnife Synchrony Respiratory Tracking System. The motion of lung tumor was measured by the coordinates of a gold acupuncture needle inserted into the tumor or the area around the tumor using the CyberKnife image guided system. Then the accuracy of radiosurgery was evaluated based on the error of correlation computed with the motion tracking system. The lung tumor motion is Cranio-Caudal direction by an average of $2.63{\pm}1.87\;mm$, moved left-right direction by $1.13{\pm}0.71\;mm$, and anterior-posterior direction by $1.74{\pm}1.16\;mm$. The degree of rotational movement was $1.66{\pm}1.66^{\circ}$ on X axis, $1.20{\pm}0.97^{\circ}$ on Y axis, and $1.18{\pm}0.73^{\circ}$ on Z axis. The vector of translation movement was measured to be $3.78{\pm}2.00\;mm$ on the average. The results show that directions of Cranio-Caudal(p < 0.001), anterior-posterior direction(p < 0.029), and three dimensional vector value(p < 0.002) showed statistical significance, because the lower side of tumor showed more intensive movement compared to the upper side of tumor. The radiosurgery was carried out by compensating the motion of tumor after accurate investigation of the correlation error with the average of $0.95{\pm}0.62\;mm$ during the lung tumor radiosurgery with the CyberKnife Synchrony Respiratory Tracking System.