• Journal of the Korea Society for Simulation
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• v.28 no.2
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• pp.71-79
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• 2019

This research proposes an automatic generation system of aimpoints with considering 3D target shapes and CEP(circular error probability) values after determining a target and an azimuth value. In the past, users decided aimpoints manually based on experience or just chose a middle point of the 3D model. Futhermore, it was not possible to select a proper position with consideration of azimuth because users should decide aimpoints before the azimuth value was determined. To solve this problem, this research provides a automatic system to compute proper aimpoints with 3D target shapes, azimuth values and CEP. This article contains the explanation of 3 steps for generating aimpoints automatically: first, generating a reference plane and candidate entry points, then computing scores of each entry points and finally determining an aimpoint from the entry point with the highest score. Users can easily determine a final aimpoint with high probability of success using this system.

• Progress in Medical Physics
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• v.20 no.4
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• pp.324-330
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• 2009

In this study, we evaluated accuracy and usefulness of CyberKnife Respiratory Tracking System ($Synchrony^{TM}$, Accuray, USA) about a moving during stereotactic radiosurgery. For this study, we used moving phantom that can move the target. We also used Respiratory Tracking System called Synchrony of the Cyberknife in order to track the moving target. For treatment planning of the moving target, we obtained an image using 4D-CT. To measure dose distribution and point dose at the moving target, ion chamber (0.62 cc) and gafchromic EBT film were used. We compared dose distribution (80% isodose line of prescription dose) of static target to that of moving target in order to evaluate the accuracy of Respiratory Tracking System. We also measured the point dose at the target. The mean difference of synchronization for TLS (target localization system) and Synchrony were $11.5{\pm}3.09\;mm$ for desynchronization and $0.14{\pm}0.08\;mm$ for synchronization. The mean difference between static target plan and moving target plan using 4D CT images was $0.18{\pm}0.06\;mm$. And, the accuracy of Respiratory Tracking System was less 1 mm. Estimation of usefulness in Respiratory Tracking System was $17.39{\pm}0.14\;mm$ for inactivity and $1.37{\pm}0.11\;mm$ for activity. The mean difference of absolute dose was $0.68{\pm}0.38%$ in static target and $1.31{\pm}0.81%$ in moving target. As a conclusion, when we treat about the moving target, we consider that it is important to use 4D-CT and the Respiratory Tracking System. In this study, we confirmed the accuracy and usefulness of Respiratory Tracking System in the Cyberknife.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.31-36
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• 2006

The evaluation of safety of simulated maneuvers is frequently analysed by so called goal line or point of interest. This paper is to suggest that regarding the results of simulation the goal analysis and in length analysis are investigated respectively and the availability of which is effective and is also to suggest closest distance to channel boundary at each ship's position, not centerline, as one of proximity measures.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.2
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• pp.35-42
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• 1998

이동로봇이 주위환경에 대해서 전혀 알지 못하고 목표점으로 주행할때, 로봇은 긴 장애물이나 오목한 장애물에 대해서 존재할 수 있는 국부최소점에 빠져 더 이상 진행을 못하는 발생할수 있다. 본 논문에서는, 이 문제를 해결하기 위하여 퍼지 이론을 사용하여 효율적인 장애물회피와 안정된 목표점 도달을 달성할수 있도록하는 알고리즘을 제시한다. 제시된 알고리즘은 상하 2층 구조로 되어 있으며, 하위층은 장애물 회피 알고리즘 및 목표점 접근 알고리즘으로, 그리고 상위층은 로봇이 이동하면서 변화하는 환경에 맞게 앞의 두 알고리즘에 적절한 가중치를 부여하는 가중치 부여 알고리즘으로 구성되어 있다. 본 논문에서 제시된 알고리즘의 타당성을 보이기 위하여 'ㄹ', 'ㅊ' 형태의 장애물 및 여러 가지 형태의 장애물이 복합적으로 존재하는 환경에서 모의실험을 행한결과, 만족할 만한 결과를 얻을 수 있었다.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2334-2336
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• 2003

이동로봇의 주행을 위해서는 주변 환경에 대한 정보와 출발점과 도착점을 기초로 한 경로 탐색 알고리즘이 필요하다. 여러 경로 탐색 알고리즘 중 A* 알고리즘은 주어진 격자로 구성한 환경 정보 지도상에서 시작점과 목표점 두 Node가 주어지면 목표점까지 Node 단위로 탐색을 실시하여 시작점과 목표점 사이에 존재하는 수많은 경로 중 최저의 이동 비용 경로를 찾는 경험적인 알고리즘이다. 본 논문은 로봇의 가상 크기가 지도의 격자 방안 보다 큰 공간상에서 이동로봇의 경로 생성을 위해 격자 단위가 아닌 로봇의 가상 크기 단위로 탐색하도록 A*알고리즘을 보완하였으며 실험 결과 보완된 A* 알고리즘이 격자 단위 탐색으로 생성한 경로보다 로봇의 주행에 더 적합한 경로를 생성하였다. 또한 이동로봇의 코너 주행시 벽과의 충돌 가능성을 최소화 시키는 안전한 주행 방법을 제시하였다.

• Progress in Medical Physics
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• v.13 no.4
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• pp.218-223
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• 2002

Stereotactic radiosurgery for intracranial lesion is well established since the Lars Leksell first introduced radiosurgery concept in 1951 Its use in the treatment of spinal lesion has been limited by the availability of effective immobilization devices. The first clinical experience of the spinal stereotactic radiosurgery technique was reported by Hamilton AJ. in 1995. Recently, Optic-guided patient positioning technique for extracranial stereotactic radiosurgery was developed and reported. This study is for assess the target positioning accuracy of the optic guided patient positioning system Exactrac (BrainLab., Inc, Germany). We have designed phantom for assess the accuracy of spinal stereotactic radiosurgery The infrared reflective body markers attached to the relatively immobile part of the body and a series of 2 mm CT images was taken. The image sets were transferred to the planning computer. During the radiosurgery treatment, we measure the real-time display showing the positioning values from Exactrac computer. And we compare the isocenter deviation from irradiated center point of the film which was mounted on the lesion site of the phantom and pin hole site of that film. The accuracy of the ExacTrac system in positioning a target point shows enough for the clinical applications.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1997.11a
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• pp.263-266
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• 1997

로봇 축구 경기를 위해서는 경기장의 임의의 시작점에서 목표점으로 장애물을 피해 갈 수 있는 능력이 필요하다. 이러한 경로 계획을 학습하기 위해서 다양한 상황을 모두 고려할 경우 학습량이 급격히 증가한다. 그러나 많은 실제적인 학습 문제에 있어서는 가능한 모든 학습 데이터를 사용하지 않고도 원하는 학습 효과를 가져올 수 있음이 알려져 있으며, 이러한 경우 데이터를 스스로 선별하여 학습하는 능동적 학습 방법이 효과적이다. 본 논문에서는 진화 알고리즘을 사용하여 실시간에 경로 계획을 하기 위한 새로운 능동적 학습 방법을 제시한다. 제안되는 방법은 두 개의 진화 알고리즘으로 구성되는데 하나는 주어진 시작점-목표점간의 최적 경로를 찾는데 사용되고 또 다른 하나의 진화 알고리즘은 유용한 시작점-목표점들의 쌍을 탐색하는데 사용된다. 이 방법은 계산 시간의 여유가 있을 때 다양한 문제를 스스로 제시하고 해결하는 법을 학습해 놓고 후에 실제 문제가 주어질 때 기존의 문제와 가장 유사한 문제를 찾아 실시간에 해결함으로써 기존의 진화 알고리즘에 의한 경로 계획법들이 갖는 실시간성에서의 단점을 개선할 수 있다. 실험을 통하\ulcorner 제안된 두 가지 진화 알고리즘의 성능을 실험적으로 검토한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.836-846
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• 2018

The purpose of this study was to evaluate nursing educational objectives achievement, critical thinking disposition, and clinical competence and their relationships in nurses within five years after graduation. Subjects were 82 nurses who graduated one nursing college within five years and 68 managers in nursing unit of hospital. Questions were given to nurses. They reported their achievement of educational objectives of the nursing college, critical thinking disposition and clinical competence. Nursing unit managers received the same questions to evaluate nurses working at their unit. Data were collected from January to march 2014 and analyzed by descriptive statistics, t-test, ANOVA, Pearson correlation and multiple regression with SPSS/WIN 23.0 program. Mean scores for achievement of educational objectives, critical thinking disposition, and clinical competence were $3.60{\pm}0.60$, $3.46{\pm}0.28$, and $4.17{\pm}0.56$, respectively. Educational objectives achievement showed significant correlations with critical thinking disposition (r = 0.52, p <. 001) and clinical competence (r = 0.52, p < .001). Regression analysis showed that critical thinking disposition (${\beta}=.30$, p = .018) and clinical competence (${\beta}=.26$, p = .029) were significant factors for predicting educational objectives achievement. Manager's evaluation score for educational objectives achievement and clinical competence was higher than graduated nurses' report (p < .001). This could be used as a feed- back to reset educational objectives and upgrade the curriculum. These study results could be used to, establish strategies to improve educational objectives achievement.

• Journal of Distribution Research
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• v.10 no.1
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• pp.85-106
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• 2005

This study has investigated the mediating effects of dependence, goal incongruence, and conflict in processing of environmental dynamism effects on the dissolution intention in the discount store industry. As the result of hypotheses test using data collected from 180 supplier samples, environmental dynamism has the positive effects on dependence, goal incongruence, and conflict. Goal incongruence has the positive effect on conflict. Goal incongruence and conflict has the positive effects on dissolution intention. But, dependence didn't decrease dissolution intention significantly. Finally, the authors discussed the theoretical contributions, managerial implications, and limitations of this study and presented the future research directions.

• Progress in Medical Physics
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• v.24 no.4
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• pp.290-294
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• 2013

Stereotactic Radiosurgery require high accuracy and precision of patient positioning and target localization. We evaluate the real time positioning accuracy of isocenter using optic guided patient positioning system, ExacTrac (BrainLab, Germany), during spinal radiosurgery procedure. The system is based on real time detect multiple body markers attached on the selected patient skin landmarks. And a custom designed patient positioning verification tool (PPVT) was used to check the patient alignment and correct the patient repositioning before radiosurgery. In this study, We investigate the selected 8 metastatic spinal tumor cases. All type of tumors commonly closed to thoracic spinal code. To evaluate the isocenter positioning, real time patient alignment and positioning monitoring was carried out for comparing the current 3-dimensional position of markers with those of an initial reference positions. For a selected patient case, we have check the isocenter positioning per every 20 millisecond for 45 seconds during spinal radiosurgery. In this study, real time average isocenter positioning translation were $0.07{\pm}0.17$ mm, $0.11{\pm}0.18$ mm, $0.13{\pm}0.26$ mm, and $0.20{\pm}0.37$ mm in the x (lateral), y (longitudinal), z (vertical) directions and mean spatial error, respectively. And body rotations were $0.14{\pm}0.07^{\circ}$, $0.11{\pm}0.07^{\circ}$, $0.03{\pm}0.04^{\circ}$ in longitudinal, lateral, table directions and mean body rotation $0.20{\pm}0.11^{\circ}$, respectively. In this study, the maximum mean deviation of real time isocenter positioning translation during spinal radiosurgery was acceptable accuracy clinically.