• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2004.10a
• /
• pp.13-16
• /
• 2004

This paper deals with a one-searcher multi-target search problem where targets with different detection priorities move in Markov processes in each discrete time over a given space search area, and the total number of search time intervals is fixed. A limited search resource is available in each search time interval and an exponential detection function is assumed. The searcher can obtain a target detection award, if detected, which represents the detection priority of target and is non-increasing with time. The objective is to establish the optimal search plan which allocates the search resource effort over the search areas in each time interval in order to maximize the total detection award. In the analysis, the given problem is decomposed into intervalwise individual search problems each being treated as a single stationary target problem for each time interval. An associated iterative procedure is derived to solve a sequence of stationary target problems. The computational results show that the proposed algorithm guarantees optimality.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.46 no.2
• /
• pp.57-71
• /
• 2023

In this study, we analyze a finite-buffer M/G/1 queueing model with randomized pushout space priority and nonpreemptive time priority. Space and time priority queueing models have been extensively studied to analyze the performance of communication systems serving different types of traffic simultaneously: one type is sensitive to packet delay, and the other is sensitive to packet loss. However, these models have limitations. Some models assume that packet transmission times follow exponential distributions, which is not always realistic. Other models use general distributions for packet transmission times, but their space priority rules are too rigid, making it difficult to fine-tune service performance for different types of traffic. Our proposed model addresses these limitations and is more suitable for analyzing communication systems that handle different types of traffic with general packet length distributions. For the proposed queueing model, we first derive the distribution of the number of packets in the system when the transmission of each packet is completed, and we then obtain packet loss probabilities and the expected number of packets for each type of traffic. We also present a numerical example to explore the effect of a system parameter, the pushout probability, on system performance for different packet transmission time distributions.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.10
• /
• pp.3423-3438
• /
• 2014

In recent years, wearable sensor devices are reshaping the way people live, work, and play. A wearable sensor device is a computer that is subsumed into the personal space of the user, and is always on, and always accessible. Therefore, among the most salient aspects of a wearable sensor device should be a small form factor, long battery lifetime, and real-time characteristics. Thereby, sophisticated applications of a wearable sensor device use real-time operating systems to guarantee real-time deadlines. The deterministic multi-dimensional task scheduling algorithms are implemented on ARC (Actual Remote Control) with relatively limited hardware resources. ARC is a wearable wristwatch-type remote controller; it can also serve as a universal remote control, for various wearable sensor devices. In the proposed algorithms, there is no limit on the maximum number of task priorities, and the memory requirement can be dramatically reduced. Furthermore, regardless of the number of tasks, the complexity of the time and space of the proposed algorithms is O(1). A valuable contribution of this work is to guarantee real-time deadlines for wearable sensor devices.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.11
• /
• pp.5449-5464
• /
• 2018

Recent works have validated the possibility of reducing the energy consumption in wireless heterogeneous networks, achieved by switching on/off some base stations (BSs) dynamically. In this paper, to realize energy conservation, the discrete time Markov Decision Process (DTMDP) is developed to match up the BS switching operations with the traffic load variations. Then, an asynchronous decision-making algorithm, which is based on the Bellman equation and the on/off priorities of the BSs, is firstly put forward and proved to be optimal in this paper. Through reducing the state and action space during one decision, the proposed asynchronous algorithm can avoid the "curse of dimensionality" occurred in DTMDP frequently. Finally, numerical simulations are conducted to validate the effectiveness and advantages of the proposed asynchronous on/off strategies.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.6
• /
• pp.107-115
• /
• 1998

A path planning using potential field method is very useful for the real-time navigation of mobile robots. However, the method needs high modeling cost to calculate the potential field because of complex preprocessing, and mobile robots may get stuck into local minima. In this paper, An efficient path planning algorithm for multiple mobile robots, based on the potential field method, was proposed. In the algorithm. the concepts of subgoals and obstacle priority were introduced. The subgoals can be used to escape local minima, or to design and change the paths of mobile robots in the work space. In obstacle priority, all the objects (obstacles and mobile robots) in the work space have their own priorities, and the object having lower priority should avoid the objects having higher priority than it has. In this paper, first, potential based path planning method was introduced, next an efficient collision-avoidance algorithm for multiple mobile robots, moving in the obstacle environment, was proposed by using subgoals and obstacle priority. Finally, the developed algorithm was demonstrated graphically to show the usefulness of the algorithm.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.4
• /
• pp.1025-1034
• /
• 1997

Inference process of resolution-based automated reasoning easily consumes the memory of computer without giving any useful result by priducing lots of fruioless information which are not necessary for the conslusion. This paper suggests a control strategy for saving the space of computer memory and reducing the inference time. The strategy uses a restriction that comparatively irrelevant axioms do mot take pare in the resoluition. In order to analyze and determine the priorities of the input axioms of joning the inference process, the system employs the fuzzy relational products.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.2
• /
• pp.317-329
• /
• 2018

The study on the existing multi-utility tunnel has examined the general aspects related to the installation of multi-utility tunnel rather than the optimal design and feasibility analysis of accommodation facility in multi-utility tunnel. In the basic planning stage related to the introduction of multi-utility tunnel, it is difficult to determine accommodation facility due to lack of relevant indicators and data. In this paper, VE/LCC analysis method is suggested for the optimal alternative decision of accommodation facilities in multi-utility tunnel. The analysis of the items of individual accommodation facility and the value index for LCC costs were applied to the kind alternatives, and the priorities of each kind were analyzed. In addition, the domestic multi-utility tunnel and analysis result are compared. The result of this study will be helpful to shorten the time and convenience of the user in the process of determining accommodation facility including the first designers when introducing multi-utility tunnel.

• Journal of Service Research and Studies
• /
• v.12 no.3
• /
• pp.134-143
• /
• 2022

TThe National Cemetery is a space for realizing patriotism at the national level to honor the will of those who gave their lives for the country and to permanently venerate their loyalty and merit. The purpose of the establishment of the national cemetery is to imitate the spirit of patriotism that was sacrificed for the country and people. The state distinguishes between private death and public death as a sacrifice for the state. Furthermore, we carefully manage deaths that are classified as public. National cemeteries are the institutional space for managing such public deaths. With respect for devotion and discipline, the standards for burial and commemoration should not be based on status or class. In a national cemetery, shifting the degree of courtesy and priorities to devotion and discipline will become a true patriotism system in a democratic society. First of all, it is time to honor those who have died and those who have dedicated themselves to the restoration of national sovereignty as the highest and highest priority. This is the key to resolving the conflict that our national cemetery is experiencing and gaining public sympathy. This study is based on the premise that the national cemetery is insufficient as an open memorial space and historical space loved by the people. In addition, the implications and applicability of national cemeteries are reviewed through domestic and foreign excellent cases and high-quality and eco-friendly national cemetery construction cases in advanced countries.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.32 no.2
• /
• pp.11-24
• /
• 2004

The purpose of this study is to present data on the human activities responding to the physical environment of ‘Ulsan’s Grand Parks by evaluating user behavior and activity, visiting motivations, and user satisfaction. This study was conducted using multi-methods such as interviews and questionnaires surveys. The main findings of this study can be summarized in six parts as follows: \circled1 Behavior patterns showed that the users visited the park left within 30 minutes and the frequency of visits was 1 or 2 times per week. They spent their time mostly on ‘walking’ and ‘picnicking’. The users visited regardless of the seasons or the day of the week. \circled2 The priorities for improvements were analyzed as follows: the users expressed their demands for ‘shadowing facilities’ like shelters and pergolas because they used these facilities frequently. Also, the users would like an ‘event program’, ‘sign system’ and ‘guide program’. \circled3 Analysis of the the user’s perception of the park showed that they perceive the park as ‘representative source of the landscape and open space in Ulsan and place for making contact with nature. \circled4 In examining the visiting motivations of the users of Ulsan Grand Park, it was revealed that people use the park for ‘time with family and friends’, ‘to escape from city life’, ‘to relieve fatigue. As a result of factor analysis, 4 factors were identified such as ‘physical motive(MF1)’, ‘exploratory motive(MF2)’, ‘social motive(MF3)’ and ‘emotional motive(MF4). \circled5 Park users’ evaluation for park facilities showed that people are satisfied with most of the facilities and especially, they have high level of satisfaction for ‘footpaths’, ‘squares’ and ‘picnicspace’. The evaluation of the park user’s of activity reveals that they are content with nearly all the variables. Especially, they have high level of satisfaction for the variables of ‘convenience for dynamic activities’, ‘making of a beautiful atmosphere, ‘accessibility from the outside’ and, ‘convenience in group activitie. Factor analysis of the park user’s of activity revealed 5 factors such as ‘convenience and interest factor (AF1)’, ‘park maintenance, management and use program(AF2)’, ‘visual beauty(AF3)’, ‘safety and accessibility(AF4)’ and ‘crowding(AF5)’. \circled6 Regression analysis was employed to get the predictor factors of overall satisfaction with a result of 60.0%($R^2$). The variance was explained as ‘quality of the picnic space’, ‘convenience and interest factor while using the park’, ‘park program for maintain and management in the park’, ‘visually beauty while using the park’, ‘safety and accessibility of the parks’, ‘quality of the pond’, ‘crowding’, ‘quality of the square’.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.4
• /
• pp.1557-1561
• /
• 2014

Background: Breast cancer is the most frequently diagnosed cancer in women and estimating its relative risks and trends of incidence at the area-level is helpful for health policy makers. However, traditional methods of estimation which do not take spatial heterogeneity into account suffer from drawbacks and their results may be misleading, as the estimated maps of incidence vary dramatically in neighboring areas. Spatial methods have been proposed to overcome drawbacks of traditional methods by including spatial sources of variation in the model to produce smoother maps. Materials and Methods: In this study we analyzed the breast cancer data in Iran during 2004-2008. We used a method proposed to cover spatial and temporal effects simultaneously and their interactions to study trends of breast cancer incidence in Iran. Results: The results agree with previous studies but provide new information about two main issues regarding the trend of breast cancer in provinces of Iran. First, this model discovered provinces with high relative risks of breast cancer during the 5 years of the study. Second, new information was provided with respect to overall trend trends o. East-Azerbaijan, Golestan, North-Khorasan, and Khorasan-Razavi had the highest increases in rates of breast cancer incidence whilst Tehran, Isfahan, and Yazd had the highest incidence rates during 2004-2008. Conclusions: Using spatial methods can provide more accurate and detailed information about the incidence or prevalence of a disease. These models can specify provinces with different health priorities in terms of needs for therapy and drugs or demands for efficient education, screening, and preventive policy into action.