• Journal of the Korean Geographical Society
• /
• v.44 no.6
• /
• pp.813-832
• /
• 2009

As accessibility to health-care service in less populated rural areas is geographically limited and demand for public health-care by the aging is increasing, a new approach for health-care service such as a home care service is becoming more popular. For a home care service, health-care personnels directly visit to location of health-care clients. Such changes in provision of health services require developing innovative and scientific approaches for efficient allocation of health resources and managing services by public health-care organizations. The purpose of this study is to formulate a location model for visiting health-care districting for the rural elderly and to develop an Automated Zoning Procedure (AZP) to solve this model. Mobility, workload balance and contiguity criteria are considered in the model. Three different objective functions are evaluated; 1) minimizing the sum of network distance between the unit areas in a district, 2) maximizing spatial interaction between the unit areas in a district, and 3) minimizing tour distance that visits each unit area exactly once in a district. The AZP for solving the model is developed and applied to a rural area. The application results demonstrate that the AZP can generate different districting systems for each objective functions.

• Journal of Intelligence and Information Systems
• /
• v.12 no.2
• /
• pp.125-144
• /
• 2006

The development of mobile applications is fast in recent years. However, nearly all applications are for messaging, financial, locating services based on simple interactions with mobile users because of the limited screen size, narrow network bandwidth, and low computing power. Processing an algorithm for supporting a group decision process on mobile devices becomes impossible. In this paper, we introduce the mobile-oriented simple interactive procedure for support a group decision making process. The interactive procedure is developed for multiple objective linear programming problems to help the group select a compromising solution in the mobile Internet environment. Our procedure lessens the burden of group decision makers, which is one of necessary conditions of the mobile environment. Only the partial weak order preferences of variables and objectives from group decision makers are enough for searching the best compromising solution. The methodology is designed to avoid any assumption about the shape or existence of the decision makers' utility function. For the purpose of the experimental study of the procedure, we developed a group decision support system in the mobile Internet environment, MOBIGSS and applied to an allocation problem of investor assets.

• Spatial Information Research
• /
• v.17 no.3
• /
• pp.269-276
• /
• 2009

For the development and management of u-City(ubiquitous city), Ubiquitous City Construction Law was enacted(March 3, 2008) to form the legal basis of u-City plan, construction and managements afterwards. Among u-City elements, the u-City Management Center has its own meaning and importance in roles which are crucial to the u-City developments, and its legal establishment is one of the core u-City realization factors. The purpose of this study is to analyse its overall problem issues regarding the function and location of u-City Management Center and then to suggest the basic direction and enforcement strategies to form its legal basis. As a result, in order to enhance the possibility of successful realization of u-City Management Center, the classification and standardization of function type, allocation of detailed functions based on u-City project hierarchy, and practical definition and relationships among basic u-City components such as u-City Service and Infrastructure were suggested. Also, practical execution devices on revenue sources and private sector participation, as well as the legal basis stipulating the mandatory inclusion of u-City Management Center development for u-City projects, were suggested.

• Journal of the Korean Society for Railway
• /
• v.19 no.2
• /
• pp.170-186
• /
• 2016

This paper introduces a multi-phase fuzzy risk graph model, representing a method for determining for SIL values for railway industry systems. The purpose of this paper is to compensate for the shortcomings of qualitative determination, which are associated with input value ambiguity and the subjectivity problem of expert judgement. The multi-phase fuzzy risk graph model has two phases. The first involves the determination of the conventional risk graph input values of the consequence, exposure, avoidance and demand rates using fuzzy theory. For the first step of fuzzification this paper proposes detailed input parameters. The fuzzy inference and the defuzzification results from the first step will be utilized as input parameters for the second step of the fuzzy model. The second step is to determine the safety integrity level and tolerable hazard rate corresponding to be identified hazard in the railway industry. To validate the results of the proposed the multi-phase fuzzy risk graph, it is compared with the results of a safety analysis of a level crossing system in the CENELEC SC 9XA WG A0 report. This model will be adapted for determining safety requirements at the early concept design stages in the railway business.

• Journal of the Korean Society for Railway
• /
• v.19 no.2
• /
• pp.145-158
• /
• 2016

This paper introduces a risk graph which is one method for determining the SIL as a measure of the effectiveness of signaling system. The purpose of this research is to make up for the weakness of the qualitative determination, which has input value ambiguity and a boundary problem in the SIL range. The fuzzy input valuable consists of consequence, exposure, avoidance and demand rate. The fuzzy inference produces forty eight fuzzy rule by adapting the calibrated risk graph in the IEC 61511. The Max-min composition is utilized for the fuzzy inference. The result of the fuzzy inference is the fuzzy value. Therefore, using the de-fuzzification method, the result should be converted to a crisp value that can be utilized for real projects. Ultimately, the safety requirement for hazard is identified by proposing a SIL result with a tolerable hazard rate. For the validation the results of the proposed method, the fuzzy risk graph model is compared with the safety analysis of the signaling system in CENELEC SC 9XA WG A10 report.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.7
• /
• pp.796-804
• /
• 2010

It is important to use the comb type pilot allocation for the continuous channel and efficient processing. And DFT-spreading OFDM is used a lot to solve high PAPR problem of OFDM system. However, PAPR is increased again when comb type pilot is used to estimate channel characteristics. So, in this paper, we employ a new SLM method to DFT-spreading OFDM system to reduce increased high PAPR. And we suggest an effective method to transmit side information without additional bandwidth. Pilot and side information must be preserved from jamming or intentional interferences since those are very important in DFT spread OFDM system using SLM. So, in this paper, we like to analyze and simulate the performance of DFT spread OFDM system based on SLM against jamming signal. To remedy the vulnerable shortcomings of DFT spread OFDM about jamming or intentional interferences, we employ FH(Frequency Hopping) method and analyze system performance under the several jamming conditions such as MTJ(Multi Tone Jamming) and PBJ(Partial Band Jamming).

• The KIPS Transactions:PartC
• /
• v.9C no.1
• /
• pp.123-134
• /
• 2002

The requirement for QoS (Quality of Service) has become an important Issue as real-time or high bandwidth services are increasing, such as Internet Telephony, Internet broadcasting, and multimedia service etc. In order to guarantee the QoS of Internet application services, several approaches are being sought including IntServ (Integrated Service) DiffServ(Differentiated Srvices), and MPLS(Multi-Protocol Label Switching). In this paper, we describe the performance analysis of QoS guarantee mechanism using the DiffServ. To analyze how the DiffServ performance was affected by diverse input traffic models and the weight value in WFQ(Weighted Fair Queueing), we simulated and performed performance evaluation under a random, bursty, and self-similar input traffic models and for diverse input parameters. leased on the results of performance analysis, it was confirmed that significant difference exist in packet delay and loss depending on the input traffic models used. However, it was revealed that QoS guarantee is possible to the EF (expedited Forwarding) class and the service separation between RF and BE (Best Effort) classes may also be achieved. Next, we discussed the performance synthesis problem. (i. e. derived the conservation laws for a DiffServ networks, and analysed the performance variation and dynamic behavior based on the resource allocation (i.e., weight value) in WFQ.

• Journal of KIISE:Computer Systems and Theory
• /
• v.30 no.5_6
• /
• pp.299-306
• /
• 2003

This paper formulates a problem of embedded real-time system re-engineering, and presents its solution approach. Embedded system re-engineering is defined as a development task of meeting performance requirements newly imposed on a system after its hardware and software have been fully implemented. The performance requirements nay include a real-time throughput and an input-to-output latency. The proposed solution approach is based on a bottleneck analysis and nonlinear optimization. The inputs to the approach include a system design specified with a process network and a set of task graphs, task allocation and scheduling, and a new real-time throughput requirement specified as a system's period constraint. The solution approach works in two steps. In the first step, it determines bottleneck precesses in the process network via estimation of process latencies. In the second step, it derives a system of constraints with performance scaling factors of processing elements being variables. It then solves the constraints for the performance staling factors with an objective of minimizing the total hardware cost of the resultant system. These scaling factors suggest the minimal cost hardware upgrade to meet the new performance requirement. Since this approach does not modify carefully designed software structures, it helps reduce the re-engineering cycle.

• Journal of KIISE:Information Networking
• /
• v.29 no.4
• /
• pp.375-385
• /
• 2002

The IETF has defined the Intserv model and the RSVP signaling protocol to improve QoS capability for a set of newly emerging services including voice and video streams that require high transmission bandwidth and low delay. However, since the current Intserv model requires each router to maintain the states of each service flow, the complexity and the overhead for processing packets in each rioter drastically increase as the size of the network increases, giving rise to the scalability problem. This motivates our work; namely, we investigate and devise new control schemes to enhance the scalability of the Intesev model. To do this, we basically resort to the SCORE network model, extend it to fairly well adapt to the three services presented in the Intserv model, and devise schemes of the QoS scheduling, the admission control, and the edge and core node architectures. We also carry out the computer simulation by using ns-2 simulator to examine the performance of the proposed scheme in respects of the bandwidth allocation capability, the packet delay, and the packet delay variation. The results show that the proposed scheme meets the QoS requirements of the respective three services of Intserv model, thus we conclude that the proposed scheme enhances the scalability, while keeping the efficiency of the current Intserv model.

• Journal of Advanced Navigation Technology
• /
• v.7 no.1
• /
• pp.59-71
• /
• 2003

The channel scheduler is suggested the radio resource management method in order to provide service with guaranteeing fairness and throughput to the users who use limited wireless channel. Proportional fairness scheduling algorithm is the channel scheduler used in the AMC(Adaptive Modulation and Coding)/TDM system, and this algorithm increases the throughput considering the user's time fairness. In this paper is suggested the channel scheduler combining CDM scheme available in AMC/TDM/CDM system. Unlike the system which only uses TDM which provide the only one user at the same slot, this scheduler can service a lot of users since this uses the CDM scheme with multi-cord channel. At every moment, allocation of transmission power to multi-channel users is problematic because of CDM scheme. In this paper, we propose a water-filling scheduling algorithm to solve the problem. Water-filling fairness(WF2) scheduling algorithm watches the average channel environment. So, this modified method guarantees fairness for each user in terms of power and service time.