• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.56-58
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• 2006

Sensing and coverage are the two relevant tasks for a sensor network. Quality of sensor network totally depends upon the sensing ability of sensors. In a certain monitored region success of detecting or sensing an object with the help of sensor network tells that how efficiently the network coverage perform. Here in this paper we have proposed a clustering algorithm for the deployment of sensors and thus calculated the object detection probability. Actually by this work we can easily identify the present network coverage status and accordingly can take action for its improvement.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.4
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• pp.321-326
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• 2015

Smart metering is one of the most implementable internet-of-thing service. In order to implement the smart metering, a wireless communication network should be newly designed and evaluated so as to satisfy quality-of-service of smart metering. In this paper, we consider a wireless network for the smart metering implemented with multi-purpose wireless chips and channel coding-functioned micro controllers. Especially, channel coding is newly adopted to improve successful frame transmission probability. Based on the successful frame transmission probability, average transmission delay and delay violation probability are analyzed. Using the analytical results, service coverage expansion is evaluated. Through the delay analysis, service feasibility can be verified. According to our results, channel coding needs not to be utilized to improve the delay performance if the smart metering service coverage is several tens of meters. However, if more coverage is required, chanel coding adoption definitely reduces the delay time and improve the service feasibility.

• Management Science and Financial Engineering
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• v.17 no.2
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• pp.39-62
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• 2011

In wireless sensor network, since each sensor is equipped with a limited power, efficient use of the energy is important. One possible network management scheme is to cluster the sensors into several sets, so that the sensors in each of the sets can completely perform the monitoring task. Then the sensors in one set become active to perform the monitoring task and the rest of the sensors switch to a sleep state to save energy. Therefore, we rotate the roles of the active set among the sensors to maximize the network lifetime. In this paper, we suggest an optimal algorithm for the maximum lifetime coverage problem which maximizes the network lifetime. For comparison, we implemented both the heuristic proposed earlier and our algorithm, and executed computational experiments. Our algorithm outperformed the heuristic concerning the obtained network lifetimes, and it found the solutions in a reasonable amount of time.

• Journal of Korean Society for Quality Management
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• v.31 no.4
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• pp.164-175
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• 2003

This paper investigates bootstrap confidence intervals of the process capability index(PCI) based on the expected loss derived from the empirical distribution function(EDF). The PCI based on the expected loss is too complex to derive its confidence interval analytically, so the bootstrap method is a good alternative. We propose three types of the bootstrap confidence interval; the standard bootstrap(SB), the percentile bootstrap(PB), and the acceleration biased­corrected percentile bootstrap(ABC). We also perform a comprehensive simulation study under various process distributions, in order to compare the accuracy of the coverage probability of the bootstrap confidence intervals. In most cases, the coverage probabilities of the bootstrap confidence intervals from the EDF PCI turned out to be more accurate than those from the PCI based on the normal distribution. It is expected that the bootstrap confidence intervals from the EDF PCI can be utilized in real processes where the true distribution family may not be known.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.10
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• pp.708-714
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• 2014

Wireless sensor networks (WSNs) generally consist of densely deployed sensor nodes that depend on batteries for energy. Having a large number of densely deployed sensor nodes causes energy waste and high redundancy in sensor data transmissions. The problems of power limitation and high redundancy in sensing coverage can be solved by appropriate scheduling of node activity among sensor nodes. In this paper, we propose a cellular automata based node scheduling algorithm for prolonging network lifetime with a balance of energy savings among nodes while achieving high coverage quality. Based on a cellular automata framework, we propose a new mathematical model for the node scheduling algorithm. The proposed algorithm uses local interaction based on environmental state signaling for making scheduling decisions. We analyze the system behavior and derive steady states of the proposed system. Simulation results show that the proposed algorithm outperforms existing protocols by providing energy balance with significant energy savings while maintaining sensing coverage quality.

• Archives of Plastic Surgery
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• v.39 no.6
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• pp.663-666
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• 2012

Current treatments for hidradenitis suppurativa (HS) include prolonged courses of antibiotics, retinoids, immunosuppressants, and biologics. Severe cases that are resistant to prolonged medical treatment pose a therapeutic challenge. We propose radical excision and lateral thoracic flap reconstruction as a treatment option for such cases. In our experience with two patients, good aesthetic and functional outcomes were achieved, with a high level of patient satisfaction. The availability of suitable flap coverage allows for wide resection of all of the hair-bearing skin, leading to a low incidence of residual disease and subsequent recurrence. Following excision of the affected tissue, the ideal reconstructive method in the axilla provides suitable coverage without unacceptable donor site morbidity and also avoids axillary contractures. A long lateral thoracic flap with delay has excellent coverage with minimal donor tissue sacrifice. With a suitable flap coverage option, the management paradigm of intractable HS should shift from prolonged medical treatment to allow decisive radical excision, which will improve the quality of life for patients.

• Journal of Communications and Networks
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• v.18 no.4
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• pp.600-609
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• 2016

In this paper, we propose a two-stage base station (BS) sleeping scheme to save energy consumption in cellular networks. The BS sleeping mode is divided into a light sleeping stage and a deep sleeping stage according to whether there is a user in the BS's coverage. In the light sleeping stage, a BS will retain its coverage and frequently switch between the on state and the doze state according to the service characteristics. While in the deep sleeping stage analysis, the BS will shut down its coverage, and neighbor BSs will patch the coverage hole. Several closed-form formulas are derived to demonstrate the power consumption in each sleeping stage and the stage switching conditions are discussed to minimize the average power consumption. The average traffic delay caused by BS sleeping and the average deep sleeping rate under a given traffic load have also been studied. In addition, it is shown that BS sleeping is not always possible because of the limited quality of service (QoS) requirements. Simulation results show that the proposed scheme can effectively reduce the average BS power consumption, at the cost of some extra traffic delay. In summary, our proposed framework provides an essential understanding of the design of future green networks that aim to take full advantage of different stages of BS sleeping to obtain the best energy efficiency.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.3
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• pp.406-412
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• 2010

In this paper, we formally define the problem of maximizing the coverage of sensor deployment, which is the optimization problem appeared in real-world sensor deployment, and analyze the properties of its solution space. To solve the problem, we proposed novel genetic algorithms, and we could show their superiority through experiments. When applying genetic algorithms to maximum coverage sensor deployment, the most important issue is how we evaluate the given sensor deployment efficiently. We could resolve the difficulty by using Monte Carlo method. By regulating the number of generated samples in the Monte Carlo evaluation of genetic algorithms, we could also reduce the computing time significantly without loss of solution quality.

• Journal of Korean society of Dental Hygiene
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• v.16 no.2
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• pp.195-204
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• 2016

Objectives: The purpose of the study is to investigate the knowledge, attitude, and recognition of health insurance coverage in tooth implant among Korean adults. Methods: A self-reported questionnaire was completed by 420 adults over 20 years lod in Seoul and Gyeonggido from October 1 to December 15, 2014. The questionnaire consisted of general characteristics of the subjects, knowledge, attitude, and recognition of health insurance coverage in tooth implant. Results: The mean of knowledge of regular checkup after implant was 3.05 points, and mean of advantage and disadvantage of implant was 3.03 points. The expectation for the implant treatment was 4.18 points and this was the highest score. There was no significant difference between the knowledge and attitude in age and monthly compensation(p>0.05). Only 45.6% of the adults were aware of the health insurance coverage of tooth implant since July, 2014. Health Insurance meeds to be modified in the beneficiaries age(44.6%), and cost(32.7%). The positive aspects of implant care included medical expenses(37.8%), health care beneficiary(29.1%), and oral health promotion(20.9%). Conclusions: Health insurance coverage of tooth implant is very important to enhance the quality of life in the adults because the proper management and implementation of the health insurance in implant will improve the oral health care in life.

• Journal of Technologic Dentistry
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• v.38 no.4
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• pp.327-342
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• 2016

Purpose: The purpose of this study was to investigate the cognition of denture fabrication activities and its cost in National Health Insurance for elderly denture. Methods: A self-administered questionnaire was completed by 41 dental laboratories' owner who was research subjects of HIRA(Health Insurance Review & Assessment Service)'s policy research for elderly denture in 2011. The questionnaire consisted of general characteristics of the subjects, dental technicians' knowledge of national health insurance coverage of elderly denture, job-related changes after national health insurance coverage of elderly denture including validity of denture fabrication activity classification and the cost for each service. Each question was measured by Likert 5 point scale or frequency. The collected data were analyzed by SPSS 16.0. Results: Most of the research subjects had been fabricating national health insurance coverage denture(92.7%), also had ample knowledge of national health insurance coverage denture for elderly. Job-related changes after national health insurance coverage of elderly denture revealed marginal differences in the quality. The validity of fabrication activity classification of resin based complete denture was $3.71{\pm}1.023$ by Likert 5 point scale. Conclusion: The goal of national health insurance for elderly denture is to promote elderly's health and well-being. To fabricate denture is a very important part of the denture treatment. For this reason, denture fabrication activity classification and the cost analysis plan should be duly reflected in the policy of national health insurance for elderly denture.