• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.12
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• pp.529-538
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• 2002

Conventional method to reduce the handoff call blocking probability(PBH) in mobile communication system is to reserve a predetermined number of channels only for handoff calls. To determine the number of reserved channels, an optimization problem, which is generally computationally heavily involved, must be solved. In this Paper, we propose a call admission control (CAC) scheme that can be used to reduce the PBH without reserving channels in advance. For this, we define a new measure, gain, which depends on the state of the system upon the arrival of a new call. The proposed CAC decision rule relies on the gain computed when a new call arrives. SRN, an extended stochastic Petri nets, provides compact modeling facilities for system analysis can be calculated performance index by appropriate reward to the model. In this Paper, we develop SRN models which can perform the CAC with gain. The SRN models are 2 level hierarchical models. The upper layer models are the structure state model representing the CAC and channel allocation methods considering QoS with multimedia traffic The lower layer model Is to compute the gain under the state of the upper layer models.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.6
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• pp.724-733
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• 1999

An effective method of system modeling and dynamic scheduling for the back-end line of semiconductor manufacturing is proposed. The virtual factory, describing semiconductor manufacturing line, is designed in detail, and then a Petri net model simulator is developed for operation and control of the modular cells of the virtual factory. The petri net model is a colored timed Petri nets (CTPNs). The simulator will be utilized to analyze and evaluate various dynamic status and operatons of manufacturing environments. The dynamic schedulaer has a hierarchical structure with the higher for planning level and the lower for dynamic scheduling level. The genetic algorithm is applied to extract optimal conditions of the scheduling algorithm. The proposed dynamic scheduling is able to realize the semiconductor manufacturing environments for the diversity of products, the variety of orders by many customers, the flexibility of order change by changing market conditions, the complexity of manufacturing processes, and the uncertainty of manufacturing resources. The proposed method of dynamic scheduling is more effective and useful in dealing with such recent pressing requirements including on-time delivery, quick response, and flexibility.

• Journal of The Korean Association For Science Education
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• v.16 no.1
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• pp.1-12
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• 1996

The purpose of this study is to investigate the psychological hierarchy structure of science concepts and to determine the effective teaching order by comparing the teaching effects of the psychological hierarchy order with those of teaching order of the current text in order to inquire validating evaluation framework of science curriculum sequence. Key concepts were selected by tasks analysis in the seven units of elementary and secondary school curriculum. Concept formation tests were developed to evaluate each concepts achievement,. The test items were made according to each of the concepts based on 12 prototype tasks developed by Frayer(1969). To identify the students' psychological hierarchy the test items were administrated to elementary and secondary school students. Ordering theory was used to identify the students' psychological hierarchy. Nonequivalent control group pretest-posttest design was used in this study as an experimental design. Teaching with psychological hierarchy order was applied tp experimental group and teaching with concept order described in the current text was applied to control group. The major results of this study are as followings: 1. The students' psychological hierarchy structures are different from logical hierarchy structures. 2. The science teachers' psychological hierarchy structures are different from not only logical hierarchy structures but also students' psychological hierarchy structures. 3. The mean score of experimental group applied psychological hierarchy order is significantly higher(p<.05) than the control group in the concept achievement.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.3
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• pp.941-955
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• 2015

In dual-channel networks (DCNs), all frequency hopping (FH) sequences used for data channels are chosen from the original FH sequence used for the control channel by shifting different initial phases. As the number of data channels increases, the hitting frequency point problem becomes considerably serious because DCNs is non-orthogonal synchronization network and FH sequences are non-orthogonal. The increasing severity of the hitting frequency point problem consequently reduces the resource utilization efficiency. To solve this problem, we propose a novel hitting frequency point collision avoidance method, which consists of a sequence-selection strategy called sliding correlation (SC) and a collision avoidance strategy called keeping silent on hitting frequency point (KSHF). SC is used to find the optimal phase-shifted FH sequence with the minimum number of hitting frequency points for a new data channel. The hitting frequency points and their locations in this optimal sequence are also derived for KSHF according to SC strategy. In KSHF, the transceivers transmit or receive symbol information not on the hitting frequency point, but on the next frequency point during the next FH period. Analytical and simulation results demonstrate that unlike the traditional method, the proposed method can effectively reduce the number of hitting frequency points and improve the efficiency of the code resource utilization.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.69-77
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• 2015

MANET is composed of only the mobile nodes have a limited transmission range. The dynamic topology by the frequent movement of nodes makes routing difficult and is also cause exposed to security vulnerabilities. In this paper, we propose the security routing technique consisted of mechanism of two steps in order to respond effectively to attack by the modification of the routing information and transmit secure data. The hierarchical structure is used and the authentication node that issues the key of the nodes within each cluster is elected in this proposed method. The authentication node manages key issues and issued information for encrypting the routing information from the source node. The reliability value for each node is managed to routing trust table in order to secure data transmission. In the first step, the route discovery is performed using this after the routing information is encrypted using the key issued by the authentication node. In the second step, the average reliability value of the node in the found path is calculated. And the safety of the data transmission is improved after the average reliability value selects the highest path. The improved performance of the proposed method in this paper was confirmed through comparative experiments with CBSR and SEER. It was confirmed a better performance in the transmission delay, the amount of the control packet, and the packet transmission success ratio.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.204-209
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• 2003

Recently, The TCN(Train Communication Network} as the distributed control systems for electric vehicles, which is the international standard of the intra vehicle communication, actively recognizes variations and supports reconfiguration of the train network when a vehicle is separated or recombined. The technique of reconfiguration to take variety and interoperability of a vehicle constitution is used when the vehicle constitution is changed. At the time, each node making up vehicle network shares the information about the variation of vehicle constitutions and the state of nodes. In the hierarchical TCN structure, an exchange of data becomes available as a work to transmit information between components is performed at the node playing a role of gateway. This paper proposes a protocol to transmit the information of the train reconfiguration. The protocol gives an application to renew a list for transmitting information and to perform the transmission that can guarantee periodic and non-periodic data transmission between nodes when the network nodes changed by a variation of the network state are reconfigured. If use this protocol, can use functions that are offered in the electric railcar at the same time that composition of vehicles is completed without delay. And when driver of the electric railcar inspect before running of vehicles, can confirm state of vehicles visually through monitor in driver's room.

• Asia-Pacific Journal of Business
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• v.12 no.2
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• pp.25-37
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• 2021

Purpose - This study analyzes the situational relationship between the components of job crafting and innovation performance, and based on this, suggests practical alternatives to the effect of the control variables of organizational support. Design/methodology/approach - For this survey, 350 questionnaires were distributed to Korean SME workers from October 5, 2020 to March 20, 2021, and 230 questionnaires were collected. In order to check the validity of the questionnaire, the questionnaire judged to be inappropriate in response was excluded. The recovery rate was 65.7%, and the effectiveness of the questionnaire was 82%. Structural equation model and hierarchical regression analysis are used to analyze those data. Findings - First, job enhancement through job redesign as well as organizational support is a key task in order to expect innovative results from field members. Innovative performance is not created by individual jobs, but is created between jobs and jobs, tasks and tasks, teams and teams, and departments and departments. This is why it is worth paying attention not to the functional approach, but to the interconnection structure of the process. Research implications or Originality - In this study, it was analyzed that structural job resource increase and social job resource increase, which are components of job crafting, had a positive effect on innovation performance, and that challenging job will had no significant effect. Challenging work will itself does not negatively affect innovation performance. Combining the survey and interview, field members who make up the majority of respondents say that they do not lack the will to work. They claim that there is no channel or opportunity to express or practice a challenging will.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.4
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• pp.51-62
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• 2004

Fuzzy supervisory control technique for the seismic response control of cable-stayed bridges subject to earthquakes is studied. The proposed technique is a hybrid control method, which adopts a hierarchical structure consisting of several sub-controllers and a fuzzy supervisor. Sub-controllers are independently designed to reduced the responses to be controlled of a cable-stayed bridge, and a fuzzy supervisor achieves improved seismic control performance by tuning the pre-designed sub-controllers. It is realized by converting static gains of the sub-controllers into time-varying dynamic gains through the fuzzy inference mechanism. To evaluate the feasibility of the proposed technique, the benchmark control problem of cable-stayed bridge proposed by Dyke et al. is adopted. The control variables for the seismic response control of the cable-stayed bridge are determined to be t도 shear forces and bending moments at the base of the towers, the longitudinal displacements at the top of the towers, the relative displacements between the deck and the tower, and the tensions in the stay cables. Comparative results between the fuzzy supervisory controller and LQG controller demonstrate the effectiveness of the proposed control technique.

• Korean Institute of Interior Design Journal
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• v.20 no.3
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• pp.249-258
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• 2011

As the elderly population are rapidly growing, the elderly who needs special care and nursing homes for them are also growing. However, many nursing homes were planned without considering the hierarchial space organization such as division of housing unit and nursing unit based on the cognitive and behavioral characteristics of the elderly or accessibility and supportiveness of the staff. This study was to examine the hierarchial characteristics in space organization of nursing homes by using Space Syntax. The subjects were 8 nursing homes in Busan. First, spaces in nursing homes were divided into five areas based on the literature review. Then the hierarchy of space organization for the access layer and layers of living floors was grasped by using G-graph. The access layer has a tree-type hierarchical structure and high visuality. Also, average depth of the space was 5. Then the full integration was analyzed. Mobile area, such as elevator, hallways, or living rooms has a high accessibility and the middle corridor type has commonly been characterized. The nursing stations were analyzed through the control degree and it was low in three nursing homes such as B, C, and G. The low clarity was showed in B, D, and F. The low clarity means that it is relatively difficult to recognize the whole space organization of nursing home. Even though the hierarchy of their living floors was tree-type structure with a high visuality, they has a type of grouping spaces around hallways and spreading, or a ring type.

• Journal of Preventive Medicine and Public Health
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• v.40 no.5
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• pp.351-362
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• 2007

Objectives: The present study was intended to assess the mental health of nurses working for university hospitals and to establish which factors determine their mental health. Methods: Self-administered questionnaires were given to 1,486 nurses employed in six participating hospitals located in Daejeon City and Chungnam Province between July 1 st and August 31st, 2006. The questionnaire items included sociodemographic, job-related, and psychosocial factors, with job stress factors (JCQ) as independent variables and indices of mental health status (PWI, SDS and MFS) as dependent variables. For statistical analysis, the Chi-square test was used for categorical variables, with hierarchical multiple regression used for determining the factors effecting mental health. The influence of psychosocial and job-related factors on mental health status was assessed by covariance structure analysis. The statistical significance was set at p<0.05. Results: The factors influencing mental health status among subject nurses included sociodemographic characteristics such as age, number of hours of sleep, number of hours of leisure, and subjective health status; job-related characteristics such as status, job satisfaction, job suitability, stresses such as demands of the job, autonomy, and coworker support; and psychosocial factors such as self-esteem, locus of control and type A behavior patterns. Psychosocial factors had the greatest impact on mental health. Covariance structure analysis determined that psychosocial factors affected job stress levels and mental health status, and that the lower job stress levels were associated with better mental health. Conclusions: Based on the study results, improvement of mental health status among nurses requires the development and application of programs to manage job stress factors and/or psychosocial factors as well as sociodemographic and job-related characteristics.