• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.887-889
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• 2003

사다리꼴-분할 방식은 로봇 경로 계획 알고리즘 중 완전 셀-분할 방식중의 하나로서 장애물과 떨어진 경로를 제공하므로 안정성을 제공하는 방식이다. 사다리꼴-분할 방식은 다각형 환경으로 이루어진 형상공간에서 정의되며 자유공간을 볼록 다각형으로 이루어진 셀(cell)로 나누어 로봇 운동을 계획하는데, 원과 같은 비다각형 장애물이 존재하는 경우에 대해서는 이 성질을 만족하는 분할 방법이 알려져 있지 않다. 본 논문에서는 기존의 다각형 환경에서 정의된 사다리꼴-분할 방식을 분할의 완전성을 잃지 않고 원의 호를 포함하는 환경으로 확장하는 알고리즘을 소개하고 구현한다.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.439-444
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• 2007

Using the anaerobic digester gas as a fuel, fuel cells have the potential to provide significant environmental and economic benefits. A molten carbonate fuel cell power plant was installed in the municipal sewage works of Tancheon in Seoul. The fuel cell unit operates on anaerobic digester gas and provides power and heat for the sewage works. This is the first project of its kind in Korea. This article outlines the experiences of gas purification process with planning, installation and operation. The engineering and installation phase is described regarding to the special features of digester gas, for example impurities in gas composition. Such impurities would be harmful to fuel cells. Operational results from the field test with a gas purification process plant are presented in this paper.

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.3
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• pp.1-10
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• 2006

In this paper we deal with a cell planning issue arisen in a CDMA based multicast network. In a CDMA based wireless network, a terminal can significantly reduce the bit error rate via the cohesion of data streams from multiple base stations. In this case, multiple base stations have to be operated according to a common time line. The cells whose base stations are operated as such are called soft-combined cells. Therefore, a terminal can take advantage of error rate reduction, if the terminal is in a soft-combined cell and at least one neighboring cell is also soft-combined. However, as soft-combining operation gives heavy burden to the network controller, the limited number of cells can be soft-combined. Our problem us to find a limited number of soft-combined cells such that the benefit of the soft-combining operation is maximized.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.10
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• pp.582-590
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• 2000

A fast optimal path planning algorithm using the analog Cellular Nonlinear Circuits(CNC) is proposed. The analog circuits based optimal path planning is very useful since most of the optimal path planning problems require real time computation. There has already been a previous study to implement the dynamic programming with analog circuits. However, it could not be applied for the practically large size of problems since the algorithm employs the mechanism of reducing its input current/voltage by the amount of cost, which causes outputs of distant cells to become zero. In this study, a subgoal-based dynamic programming algorithm to compute the optimal path is proposed. In the algorithm, the optimal paths are computed regardless of the distance between the starting and the goal points. It finds subgoals starting from the starting point when the output of the starting cell is raised from its initial value. The subgoal is set as the next initial position to find the next subgoal until the final goal is reached. The global optimality of the proposed algorithm is discussed and two different kinds of simulations have been done for the proposed algorithm.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.866-870
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• 1995

To make a mobile robot to get to a goal point, path which connects the mobile robot and the goal point is needed and a path planning is necessary. There are various kinds of a path planning. Well known methods are skeleton method, cell decomposition method and potential field method. But each method has both fortes and defects. In this paper, we propose a new method of path planning to find a path for mobile robot. It is obtained by modifying a Voronoi diagram. An original Voronoi diagram can make a safe path but its result is not satisfied. First defect of path, finded by the original Voronoi diagram, is sulplus of safty which make a path longer. Second defect is that the original Voronoi diagram method has a problem of connecting the Voronoi daigram with start/goal point of mobile robot. These defects are removed in proposed algorithm in this paper. We define a function to show the quality of paths. And by computer simulation, paths are compared and its result are shown.

• Journal of the Korean Society of Radiology
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• v.13 no.1
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• pp.39-44
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• 2019

Radiation safety management is being considered very important since radioactive isotopes such as Co-60 and Ir-192 are widely used in fields such as non-destructive test(NDT). In this study, the applicability of Mercury(II) Iodide($HgI_2$) source for tracing system was evaluated. To make sure the unit cell sensor's reliability, we evaluated the electrical properties of the sensor made with $HgI_2$, and then position dependence of the sensor was analyzed and compared with the dose distribution from the planning system. As a result of the evaluation, high reliability of the sensor was shown through the linearity of R-sq > 0.990 and reproducibility of CV < 0.015. In the position dependence evaluation, the maximum value was measured at the isocenter of the sensor and gradually decreased according to the distance. However, the dose distribution data from the planning system was turned out that has difference with that of the sensor up to 30%. This seems to come from the difference between single-point measuring based planning system and area measuring based sensor.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.56-56
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• 2003

For the treatment of superficial tumors like squamous cell carcinoma of the head and neck, 6 MV photon beam is not appropriate and a spoiler is widely used to increase dose in the buildup region, while preserving the skin sparing effect. However, commercially available treatment planning systems assume a normal unspoiled beam, thereby cannot predict the buildup dose with spoiler accurately. We aimed to implement a Monte Carlo (MC) based planning system to apply it to the radiation treatment of head and neck. Lucite with thickness of 10-mm was used for the beam spoiler with Siemens Primus 6 MV photon beam. BEAM/DOSXYZ MC system was employed to model the linac and the spoiler. To verify the calculation accuracy of MC simulations, the percent depth doses (PDDs) and profiles with and without spoiler were measured using a parallel-plate chamber. For the MC based planning, we adopted a hybrid interface system between Pinnacle (Philips, USA) and BEAM/DOSXYZ to support treatment parameters of Siemens linac and the spoiler. The measurements of PDDs and profiles agreed with the corresponding MC simulations within 2% (lSD), which demonstrate the reliability of our MC simulations. The spoiler generated electrons make a contribution to the absorbed dose up to depth of 2cm, which shows that the dominant source of increased dose from spoiler system is the contaminating electrons created by the spoiler. The whole procedures necessary for MC based treatment planning were performed seamlessly between Pinnacle and BEAM/DOSXYZ system. This ability helps to increase the clinical efficiency of the spoiler technique. In conclusion, we implemented a MC based treatment planning system for a 6 MV photon beam with a spoiler. We demonstrate sophisticated MC technique makes it possible to predict dose distributions around buildup region accurately.

• Journal of Energy Engineering
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• v.11 no.3
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• pp.216-223
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• 2002

Generation facilities of the power system are mainly classified into large-scale concentrated generation and small-scale dispersed generation, but generation planning of the Korea power system has been focusing on the large-scale generation so far. Recently, however, applications of dispersed generation sources including solar cell, fuel cell, wind power, etc. have been rapidly increasing and being strongly promoted, and such generation sources should be comprehensively considered in both planning and operating. Since it is not always possible that the dispersed generation alone meets all the load interconnected to it is especially when a fault occurs, interconnection into the existing utility is desirable and recommended. In relation to wind power generation systems interconnected at the low and extra high voltage levels, this paper performs the simulation and analysis of the system protection and suggests protection coordination plans on various faults which possibly occur.

• Radiation Oncology Journal
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• v.35 no.2
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• pp.180-184
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• 2017

Patients with locally advanced lung cancer and very limited pulmonary function (forced expiratory volume in 1 second $[FEV1]{\leq}1L$) have dismal prognosis and undergo palliative treatment or best supportive care. We describe two cases of locally advanced node-positive non-small cell lung cancer (NSCLC) patients with very limited lung function treated with induction chemotherapy and moderate hypofractionated image-guided radiotherapy (Hypo-IGRT). Hypo-IGRT was delivered to a total dose of 45 Gy to the primary tumor and involved lymph nodes. Planning was based on positron emission tomography-computed tomography (PET/CT) and four-dimensional computed tomography (4D-CT). Internal target volume (ITV) was defined as the overlap of gross tumor volume delineated on 10 phases of 4D-CT. ITV to planning target volume margin was 5 mm in all directions. Both patients showed good clinical and radiological response. No relevant toxicity was documented. Hypo-IGRT is feasible treatment option in locally advanced node-positive NSCLC patients with very limited lung function ($FEV1{\leq}1L$).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.519-522
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• 1997

In this study, the collision free path planning method of the articulated manipulator using sequential search is proposed. This method is to find the joint path of the manipulator with many degrees of freedom from the distal joint to the proximal one. To do this, the initial work space of the gantry manipulator, which is a remote maintenance equipment of the radioactive environment, is defined from the condition that the distal joint configuration is determined by the posture of maintenance. Then, 2-dimensional configuration space with the obstacle area is represented and the collision free path of manipulator is searched in the configuration space. And, this method is verified using the graphic simulation in virtual workcell for the spent fuel disassembling processes. The result of this study can be effectively used in implementing the maintenance processes for the hot cell equipment and enhance the reliability of the spent fuel management.