• Korean Management Science Review
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• v.23 no.3
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• pp.225-242
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• 2006

The Spectrum Usage Fee System which has been introduced and enforced since 1993 has had a great role for effective use of the radio frequency resources and the promotion of radio wave industry. However, the current system has been criticized due to several drawbacks. For example, broadcasting stations and national institutions are exempted whereas the overdue utility rate on some frequency has been imposed. So there has been rising the questions on whether the principles of fair imposition are broken. Another problem regarding the current system is that how to calculate the fee is too much complicated, and it needs to be revised into a simpler and clearer formulation. In this regard, this study intends to propose a new calculation framework for the radio spectrum usage fee and then prove its validity empirically on the basis of real data gathered from MIC and focus group interview.

• Korean Management Science Review
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• v.29 no.2
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• pp.65-77
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• 2012

With the explosivley increasing demand in wireless telecommunication service, the shortage of radio spectrum has been worsen. The traditional approach of the current fixed spectrum allocation leads to spectrum underutilization. Recently, CR (Cognitive Radio) technologies are proposed to enhance the spectrum utilization by allocating dynamically radio resources to CR Networks. In this study, we consider a radio resource(power, subcarrier) allocation problem for OFDMA-based CRN in which a base station supports a variety of CUs (CRN Users) while avoiding the radio interference to PRN (Primary Radio Network). The problem is mathematically formulated as a general 0-1 IP problem. The optimal solution method for the IP problem requires an unrealistic execution time due to its complexity. Therefore, we propose an heuristic that gives an approximate solution within a reasonable execution time.

• Electronics and Telecommunications Trends
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• v.26 no.6
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• pp.129-138
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• 2011

미래의 고속 및 광대역 서비스에 대한 수요 증가로, 부족한 스펙트럼을 효율적으로 사용할 수 있는 스펙트럼 관리(spectrum management) 방법의 중요성이 대두되고 있다. 또한, 트래픽 폭증 및 멀티미디어 제공 등 서비스 확대에 대응할 수 있는 유연한 스펙트럼 접속(spectrum access) 기술, 공유(sharing)에 대한 필요성도 증대되고 있다. 이러한 중요성 및 필요성에 기인해, 효율적으로 스펙트럼을 공유할 수 있는 방법으로 언더레이, 오버레이 방식 등이 제안되었고, UWB 및 인지무선(cognitive radio)과 같은 공유 기술 등이 발전하게 되었다. 본 고에서는 효율적 주파수 이용을 위한 스펙트럼 관리 방법 및 주파수 공유 기술로 기존의 주파수 대역에서 충분히 낮은 출력으로 전파를 송출하는 언더레이 방식, 기회주의적인 오버레이 동적접속 기술, 면허권자인 1차 우선 사용자(primary user)와 2차 면허권자(secondary user) 간의 동적접속 기술에 대한 국내 외 기술동향을 상세히 소개하고자 한다.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.3
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• pp.75-83
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• 2011

Cognitive radio (CR) technology is to maximize the spectrum utilization by allocating the unused spectrums to the unlicensed users. This technology enables the sharing of channels among secondary (unlicensed) and primary (licensed) users on a non-interference basis after sensing the vacant channel and as a result, it is possible to harness wireless frequency more efficiently. To enhance the accuracy of sensing, RDSS was suggested. It is a fusion mechanism based on the reputation of sensing nodes and WSPRT (weighted sequential probability ratio test). However, in RDSS, the execution number of WSPRT could increase according to the order of inputted sensing values, and the fast defense against the forged values is difficult. In this paper, we propose a transaction signing-based authentication scheme for secure distributed spectrum sensing to response the forged values. The validity of proposed scheme is provided by BAN logic.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.4
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• pp.1192-1207
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• 2014

Dynamic spectrum sharing is a key technology to improve spectrum utilization in wireless networks. The elastic spectrum management provides a new opportunity for licensed primary users and unlicensed secondary users to efficiently utilize the scarce wireless resource. In this paper, we present a game-theoretic framework for dynamic spectrum allocation where the primary users rent the unutilized spectrum to the secondary users for a monetary profit. In reality, due to the ON-OFF behavior of the primary user, the quantity of spectrum that can be opportunistically shared by the secondary users is limited. We model this situation with the renewal theory and formulate the spectrum pricing scheme with the Bertrand game, taking into account the scarcity of the spectrum. By the Nash-equilibrium pricing scheme, each player in the game continually converges to a strategy that maximizes its own profit. We also investigate the impact of several properties, including channel quality and spectrum substitutability. Based on the equilibrium analysis, we finally propose a decentralized algorithm that leads the primary users to the Nash-equilibrium, called DST. The stability of the proposed algorithm in terms of convergence to the Nash equilibrium is also studied.

• ETRI Journal
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• v.32 no.2
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• pp.292-301
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• 2010

Increasing convergence among heterogeneous radio networks is expected to be a key feature of future ubiquitous services. The convergence of radio networks in combination with dynamic spectrum allocation (DSA) could be a beneficial means to solve the growing demand for radio spectrum. DSA might enhance the spectrum utilization of involved radio networks to comply with user requirements for high-quality multimedia services. This paper proposes a simple spectrum allocation algorithm and presents an analytical model of dynamic spectrum resource allocation between two networks using a 4-D Markov chain. We argue that there may exist a break-even point for choosing whether or not to adopt DSA in a system. We point out certain circumstances where DSA is not a viable alternative. We also discuss the performance of DSA against the degree of resource sharing using the proposed analytical model and simulations. The presented analytical model is not restricted to DSA, and can be applied to a general resource sharing study.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.4
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• pp.57-66
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• 2003

The purpose of this study is to evaluate the resource value of existing mud flats in JANGWHARI, KANGWHADO, as strategies for ecotourism. The research methods used in this study are Limits of Acceptable Change(LAC), and Recreation Opportunity Spectrum(ROS). The LAC process draws attention to the existing area conditions that are judged to be acceptable. Managers must define desired area conditions and undertake actions to maintain or achieve these conditions. The ROS is within each of the recreation opportunity classes identified as being used at the regional level. The Results of this study are as follows: 1) The Opportunity Class of the ROS is ecological, physical, social, managerial setting as primitive, semi-primitive. non-motorized, semi-primitive$.$motorized, and roaded natural. 2) The indicator of the LAC is ecological, physical, social, and managerial setting; the indicator of ecological is wildlife populations, water quality, road paving; the indicator of physical is facilities; the indicator of social is visitor needs for knowledge, adventure, eco-experience, and environmental education programs; and, the indicator of managerial is limits of law, and degree of management. 3) Currently, the Opportunity Class of the ROS of JANGWHARI, KANGWHADO is levels II-III, and the Opportunity Class of the suggested ROS is levels I-II. 4) This paper describes strategies for mud flat area management: detection of water quality, resolving problems of equipment, supply of both environmental education programs and guide equipment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.11
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• pp.1033-1040
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• 2012

Recently, several researches are focused on the frequency sharing and the liberalization of frequency use for utilizing the limited frequency resources efficiently. In military, as Network Centric Warfare(NCW), which requires significant mutual operability of battle elements and real-time operation speed, has come to the fore front as an important aspect of modern warfare, the methods to manage limited frequency resources in wireless communications environment efficiently has been studied and utilized. In this paper, we propose a Spectrum COP(Common Operation Picture) design suitable for the battlefields of air force. To construct the Spectrum COP of Air Force, we analyze the requirements and design the frequency management system by using EA(Enterprise Architecture) Framework. The simulation results of the proposed design proved the effectiveness by using EADSIM(Extended Air Defense Simulation) of Air Force.

• Journal of Korean Society of Neurocognitive Rehabilitation
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• v.10 no.2
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• pp.1-7
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• 2018

The study has compared normally developed children and children who were diagnosed as autism spectrum in goal management training them to observe the effect. The research was conducted to four normally developed children and four children who were diagnosed as autism spectrum, and all subjects were provided with identical goal management training. The children and the caregivers have selected desired objectives activity, and all three activities were followed by goal management training. Intervention periods were conducted ten times in total, two times a week for five weeks, and eight subjects in the two groups were trained one on one by the researcher. The training time was 40 minutes for every session. The descriptive statistics and frequency analysis were used as the statistical method, and the Mann-Whitney test, the nonparametric statistical analysis, was conducted to compare the difference between the two groups. Goal management training for two groups did not show a statistically significant difference in terms of the performance status of Canadian Occupational Performance Measure (p>.05). In the summary of Bruininks-Oseretsky Test of Motor Proficiency (2nd) which evaluates the motor skill, there was a statistically significant difference between the autism spectrum disorder group and normal group (p<.05). Additionally, the two groups showed a statistically significant difference in eye-hand coordination sub-test among Developmental Test of Visual Perception (2nd) which evaluates the visual perception performance (p<.05). The research has confirmed the applicability of goal management training to children with autism spectrum compared to the normally developed children, and it has confirmed the effectiveness of the training.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.10
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• pp.995-1004
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• 2014

Due to the development of spectrum use technology and various services based on radio spectrum, the scarcity of spectrum has been heightened. In this circumstances both the efficiency and fairness of spectrum use need to be raised. Open spectrum access can be a useful approach for both goal. For the open spectrum access the legal institution needs to be reformed to enable it. From the starting point of spectrum use till the end of spectrum use there can be various issues of rights and obligations. So the legal institution for various legal status of spectrum use and establishment and continuous management of DB and fast and respectable dispute resolution mechanism is required.