• Nuclear Engineering and Technology
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• 제51권3호
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• pp.825-836
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• 2019

One of the most challenging safety precautions for workers in dynamic, radioactive environments is avoiding radiation sources and sustaining low exposure. This paper presents a sampling-based algorithm, DL-RRT*, for minimum dose walk-path re-planning in radioactive environments, expedient for occupational workers in nuclear facilities to avoid unnecessary radiation exposure. The method combines the principle of random tree star ($RRT^*$) and $D^*$ Lite, and uses the expansion strength of grid search strategy from $D^*$ Lite to quickly find a high-quality initial path to accelerate convergence rate in $RRT^*$. The algorithm inherits probabilistic completeness and asymptotic optimality from $RRT^*$ to refine the existing paths continually by sampling the search-graph obtained from the grid search process. It can not only be applied to continuous cost spaces, but also make full use of the last planning information to avoid global re-planning, so as to improve the efficiency of path planning in frequently changing environments. The effectiveness and superiority of the proposed method was verified by simulating radiation field under varying obstacles and radioactive environments, and the results were compared with $RRT^*$ algorithm output.

• 동서간호학연구지
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• 제10권1호
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• pp.117-125
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• 2004

Purpose: This study was attempted to investigate the demand, the recognition, and the attitude of general people on Natural Family Planning Method(NFP), and to provide basic data for a development of a program to establish a healthy sexual life. Method: This is a descriptive correlative study, collecting data by questionnaires. The subjects were 130 people of three urban areas from March 1 to April 15, 2004. The measurement tool used was about demand, recognition, and attitude to the natural birth control method. The data analysis was done by number, percent and T-test, Pearson's correlation coefficient, using SPSS program. Results: The recognition, attitude, and demand to natural birth control method was 3.01, 2.84 and 2.73 respectively. The higher recognition of correlation for natural family planning, the higher attitude(r=.864, p=.000) and demand(r= .525, p=.000) of correlation for natural family planning. It was confirmed that the study subjects almost produced self esteem and confidence recognizing at the idea of life and self value, and positively thought of need, recognition, and attitude of natural family planning method which could keep their own health management. Conclusion: As the result above, we suggest that an educational program should be developed, diffused and supported, and culturally formed by nation and social group to insist the benefit of conjugal relations in natural family planning as well as to support the knowledge deficit.

• 로봇학회논문지
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• 제5권4호
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• pp.332-338
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• 2010

This paper presents a study of path-planning method for AGV(automated guided vehicle) based on path-tracking. It is important to find an optimized path among the AGV techniques. This is due to the fact that the AGV is conditioned to follow the predetermined path. Consequently, the path-planning method is implemented directly affects the whole AGV operation in terms of its performance efficiency. In many existing methods are used optimization algorithms to find optimized path. However, such methods are often prone with problems in handling the issue of inefficiency that exists in system's operation due to inherent undue time delay created by heavy load of complex computation. To solve such problems, we offer path-planning method using modified binary tree. For the purpose of our experiment, we initially designed a AGV that is equiped with laser navigation, two encoders, a gyro sensor that is meant to be operated within actual environment with given set of constrictions and layout for the AGV testing. The result of our study reflects the fact that within such environments, the proposed method showed improvement in its efficiency in finding optimized path.

• 제어로봇시스템학회논문지
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• 제17권6호
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• pp.513-520
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• 2011

This paper presents the motion planning of robotic vehicles for the path tracking and the obstacle avoidance. To follow the given path, the vehicle moves through the turning radius obtained through the pure pursuit method, which is a geometric path tracking method. In this paper, we assume that the vehicle is equipped with a 2D laser scanner, allowing it to avoid obstacles within its sensing range. The turning radius for avoiding the obstacle, which is inversely proportional to the virtual force, is then calculated. Therefore, these two kinds of the turning radius are used to generate the steering angle for the front wheel of the vehicle. And the vehicle reduces the velocity when it meets the obstacle or the large steering angle using the potentials of obstacle points and the steering angle. Thus the motion planning of the vehicle is done by planning the steering angle for the front wheels and the velocity. Finally, the performance of the proposed method is tested through simulation.

• 대한산업공학회지
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• 제41권3호
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• pp.275-286
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• 2015

In this paper, we propose a practical method for setting up a daily production plan which can operate semiconductor fabrication factories more stably and linearly by determining work in process (WIP) targets and movement targets. We first adjust cycle times of the operations to satisfy the monthly production plan. Second, work in process (WIP) targets are determined to control the production progress of operations: earliness and tardiness. Third, movement targets are determined to reduce cumulated differences between WIP targets and actual WIPs. Finally, the determined movement targets are modified through a simulation model which considers capacities of the equipments and allocations of the WIPs in the fab. The proposed daily production planning method can be easily adapted to the memory semiconductor fabs because the method is very simple and has straightforward logics. Although the proposed method is simple and straightforward, the power of the method is very strong. Results from the shop floor in past few periods showed that the proposed methodology gives a good performance with respect to the productivity, workload balance, and machine utilization. We can expect that the proposed daily production planning method will be used as a useful tool for operating semiconductor fabrication factories more efficiently and effectively.

• 대한교통학회지
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• 제13권1호
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• pp.153-165
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• 1995

The budget management in Korea is one-year budget system which is just following int he steps of last years budget plan. This system towards traditional item-by-item and restriction-centered budget system. The budget distribution without establishing and considering rational policy goals and directions have brought inefficient resource allocations. In order to promote the implementation of transportation planning, there are some alternatives like introduction of top-down planning system preparing for the provincial self-government era. In this study, the most efficient alternatives to promote the existing management system is referring by foreign countries transportation planning examples(BVWP system in Germany). First of all, mid-long term transportation and budget planning should be established and then make decisions of resource availability and allocation. In order to provide ration budget planning, introduction of Transportation Planning Programming Budget System(TPBS) has been judged as one of the method of unifying the sysematic transportation improvement planning and budgeting. All transporation planning and related activites can not be expressed in quantity and due to the limitation of excessive cost of analyzing transportation planning and ranking priority, here after, the continuous study to minimize the evaluation cost and introduction of TPBS should be done.

• International Journal of Contents
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• 제14권3호
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• pp.7-16
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• 2018

The extent and depth of the event plan determines the scope of pedagogical experience in situations and consequently the quality of immersive learning based on our simulated world. In contrast to planning in conventional narrative-based systems mainly pursuing dramatic interests, planning in virtual world-based pedagogical systems strive to provide realistic experiences in immersed situations. Instead of story plot comprising predetermined situations, our inter-event planning method aims at simulating diverse situations that each involve multiple events coupled via their associated agents' conditions and meaningful associations between events occurring in a background world. The specific techniques to realize our planning method include, two-phase planning based on inter-event search and intra-event decomposition (down to the animated action level); autonomous and independent agents to behave proactively with their own belief and planning capability; full-blown background world to be used as the comprehensive stage for all events to occur in; coupling events via realistic association types including deontic associations as well as conventional causality; separation of agents from event roles; temporal scheduling; and parallel and concurrent event progression mechanism. Combining all these techniques, diverse exogenous events can be derived and seamlessly (i.e., semantically meaningfully) integrated with the original event to form a wide scope of situations providing chances of abundant pedagogical experiences. For effective implementation of plan execution, we devise an execution scheme based on multiple priority queues, particularly to realize concurrent progression of many simultaneous events to simulate its corresponding reality. Specific execution mechanisms include modeling an action in terms of its component motions, adjustability of priority for agent across different events, and concurrent and parallel execution method for multiple actions and its expansion for multiple events.

• 로봇학회논문지
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• 제18권1호
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• pp.1-9
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• 2023

This paper presents an optimal path planning strategy for aerial searching and surveying of a user-designated area using multiple Unmanned Aerial Vehicles (UAVs). The method is designed to deal with a single unseparated polygonal area, regardless of polygonal convexity. By defining the search area into a set of grids, the algorithm enables UAVs to completely search without leaving unsearched space. The presented strategy consists of two main algorithmic steps: cellular decomposition and path planning stages. The cellular decomposition method divides the area to designate a conflict-free subsearch-space to an individual UAV, while accounting the assigned flight velocity, take-off and landing positions. Then, the path planning strategy forms paths based on every point located in end of each grid row. The first waypoint is chosen as the closest point from the vehicle-starting position, and it recursively updates the nearest endpoint set to generate the shortest path. The path planning policy produces four path candidates by alternating the starting point (left or right edge), and the travel direction (vertical or horizontal). The optimal-selection policy is enforced to maximize the search efficiency, which is time dependent; the policy imposes the total path-length and turning number criteria per candidate. The results demonstrate that the proposed cellular decomposition method improves the search-time efficiency. In addition, the candidate selection enhances the algorithmic efficacy toward further mission time-duration reduction. The method shows robustness against both convex and non-convex shaped search area.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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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.

• 한국측량학회지
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• 제8권1호
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• pp.31-40
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• 1990

본 연구는 사친 측량을 이용한 효율적인 초구장 기본 계획을 수립하고자 연구 대상지를 선정하여 종래 방법과 사진측량 방법을 비교 분석하였다. 또한, 대상지 항공사진과 지형도를 이용하여 사친 판독에 의해 식생, 수계도를 작성하고, 대상지를 격자로 구성하여 수치지형모델에 의한 지형 변화 및 경관을 예측하므로서 계획에 필요한 여러 요소를 종래방법과 비교 고찰하였다. 본 연구 결과 사진 판독에 식생도 및 수계도를 작성하므로서 기존 조사방법 보다 세밀한 결과를 얻을 수 있었고, 수치지형모델을 이용하여 지형, 경관 및 수계 등의 변화를 표현, 예측하므로서 우수처리, 경관, 조경 계획을 효율적으로 할 수 있었다. 또한, 항공사진과 지형도를 병용하므로서 토지 이용 계획과 기타 계획에 관하여 종래 방법보다 효율적임을 제시할 수 있었다.