• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.243-246
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• 2019

In cognitive radio networks, secondary transmitters should cease its transmission immediately under the detection of primary transmission in the spectrum they are using. Then they need to exploit another idle spectrums and resynchronize to the newly found idle spectrums. Most of related work presume the existence of separate control channel used by secondary users commonly for exchanging the information of idle spectrums. However, this presumption is not feasible in real world cognitive radio scenario. Therefore we address a proactive spectrum synchronization scheme with no need of separate control channel. Our scheme lets secondary users exchange the spectrum information periodically during normal communication process and determine the next spectrum band in advance of detecting primary transmission. We evaluate our scheme in a real world cognitive radio environments set up with USRPs.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.222-225
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• 2013

무선 네트워크 환경에서 스펙트럼 자원을 효율적으로 활용할 수 있는 무선 인지 (Cognitive Radio, CR) 중 기지국이나 접속점과 같은 중앙 제어장치가 없는 분산형 무선 인지 네트워크 (Distributed Cognitive Radio Network, DCRN)에서는 부 사용자 (Secondary User, SU)들의 하드웨어적 한계로 인해 주 사용자 (Primary User, PU)들에게 인가된 스펙트럼의 모든 정보를 알 수 없다. 이를 극복하기 위해 SU들은 협력적 스펙트럼 감지 (Cooperative Spectrum Sensing)를 통하여 지역적인 스펙트럼 정보를 서로 교환하여 전체 스펙트럼의 정보를 파악한다. 본 논문은 효율적인 협력적 스펙트럼 감지를 위하여 PU 채널 상태의 비율을 사용한 정책 기반 감지 채널 선택 방법인 비율 기반 감지 정책 (Proportion-based Sensing Policy, PSP)을 제안한다. 각 SU가 PU의 채널 사용을 감지하고 PU 채널들의 idle 상태의 비율을 계산하고, 이 결과를 바탕으로 감지하는 PU 채널 변경 시, 높은 idle 비율을 갖는 PU 채널을 우선적으로 선택하여 감지되는 PU 상태가 idle 일 확률을 높여 효율적인 채널 감지를 가능하게 한다. 시뮬레이션 결과를 통하여 기존에 제안된 채널 감지 정책보다 비율 기반의 채널 감지 정책이 효율적으로 PU 채널들을 감지하는 것을 알 수 있다.

• Journal of the Korean Institute of Educational Facilities
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• v.28 no.2
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• pp.3-10
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• 2021

Community-based design is also becoming important in Korea recently. However, the existing design methods of the "conformity" method had the problem of excluding the participation of residents. Therefore, the "decision-making" method, in which residents participate in the design themselves, is drawing attention. Development of specific methods is important for residents to actively participate in "decision making." The theory of "Design Games" has long been studied as a method of community-based design in many countries. The old downtown areas of Jeju Special Self-Governing Province are increasing in number of buildings abandoned due to aging and declining. Abandoned buildings are causing many social problems. A decision-making method has been developed in Jeju for the regeneration design of abandoned buildings. This study conducted a design workshop involving residents on abandoned buildings in the old city center of Jeju City. The possibility and task of decision-making method were analyzed. As a result, participating residents were actively involved in decision-making. It also helped residents understand and learn about the attractions of the neighborhood. Meanwhile, there were also difficulties in communicating among some participants. This is a structural problem with this method. Studies have also shown that it is important for residents themselves to try to understand the neighborhood.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.6
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• pp.1292-1305
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• 2013

Along with the strengthening vehicle environmental regulations and the growing needs for the energy consumption reduction technology, the researches on the engine idle stop system, have been briskly carried out around the automobile manufacturers before the development of alternative energy. Furthermore, there is a movement to disseminate the environment friendly idle stop system by combining the system to the generalized smart key system to not only increase purchasing but also provide the convenience and save the energy as well. In this paper, we designed and implemented the idle stop system algorithm for the aftermarket smart key system with the OBD-II interface. The implemented start stop system is capable of controlling two independent systems, the smart key system and intelligent idle stop system, on a single ECU. In addition, the implemented start stop system standardizes the communication interface with the vehicles to reduce the time required for installing the start stop system to the various vehicles, and satisfies every standard response time limit for the vehicle status request signals.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.6
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• pp.460-469
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• 2015

This study's aim is for reducing big data transfer time of IoT healthcare devices by modulating digital bits into Manchester code including zero-voltage idle as information for secondary compressed binary cluster's compartment after two step compression of compressing binary data into primary and secondary binary compressed clusters for each binary clusters having compression benefit of 1 bit or 2 bits. Also this study proposed that as department information of compressed binary clusters, inserting idle signal into Manchester code will have benefit of reducing transfer time in case of compressing binary cluster into secondary compressed binary cluster by 2 bits, because in spite of cost of 1 clock idle, another 1 bit benefit can play a role of reducing 1 clock transfer time. Idle signal is also never consecutive because the signal is for compartment information between two adjacent secondary compressed binary cluster. Voltage transition on basic rule of Manchester code is remaining while inserting idle signal, so DC balance can be guaranteed. This study's simulation result said that even compressed binary data by another compression algorithms could be transferred faster by as much as about 12.6 percents if using this method.

• Journal of Environmental Impact Assessment
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• v.32 no.6
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• pp.556-576
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• 2023

This study attempted to find a way to utilize idle spaces in rural areas as a way to respond to rural extinction. Based on the keywords "startup," "youth start-up," and "youth start-up+rural," start-up+rural," the study sought to identify the perception of idle facilities in rural areas through the keywords "Idle facilities" and "closed schools." The study presented basic data for policy direction and plan search by reviewing frequency analysis, major keyword analysis, network analysis, emotional analysis, and domestic and foreign cases. As a result of the analysis, first, it was found that idle facilities and school closures are acting importantly as factors for regional regeneration. Second, in the case of youth startups in rural areas, it was found that not only education on agriculture but also problems for residence should be solved together. Third, in the case of young people, it was confirmed that it was necessary to establish digital utilization for agriculture by actively starting a business using digital. Finally, in order to attract young people and revitalize the region through best practices at home and abroad, policy measures that can serve as various platforms such as culture and education as well as startups should be presented in connection with local residents. These results are significant in that they presented implications for youth start-ups in rural areas by reviewing start-up recognition for the influx of young people as one of the alternatives for the use of idle facilities and regional regeneration, and if additional solutions are presented through field surveys, they can be used to set policy goals that fit the reality.

• Journal of Intelligence and Information Systems
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• v.29 no.1
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• pp.79-105
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• 2023

Due to unprecedented extreme weather events such as global warming and climate change, many parts of the world suffer from severe pain, and economic losses are also snowballing. In order to address these problems, 'The Paris Agreement' was signed in 2016, and an intergovernmental consultative body was formed to keep the average temperature rise of the Earth below 1.5℃. Korea also declared 'Carbon Neutrality in 2050' to prevent climate catastrophe. In particular, it was found that the increase in temperature caused by greenhouse gas emissions hurts the environment and society as a whole, as well as the export-dependent economy of Korea. In addition, as the diversification of transportation types is accelerating, the change in means of choice is also increasing. As the development paradigm in the low-growth era changes to urban regeneration, interest in idle railway sites is rising due to reduced demand for routes, improvement of alignment, and relocation of urban railways. Meanwhile, it is possible to partially achieve the solar power generation goal of 'Renewable Energy 3020' by utilizing already developed but idle railway sites and take advantage of being free from environmental damage and resident acceptance issues surrounding the location; but the actual use and plan for these solar power facilities are still lacking. Therefore, in this study, using the big data provided by the Korea National Railway and the Renewable Energy Cloud Platform, we develop an algorithm to discover and analyze suitable idle sites where solar power generation facilities can be installed and identify potentially applicable areas considering conditions desired by users. By searching and deriving these idle but relevant sites, it is intended to devise a plan to save enormous costs for facilities or expansion in the early stages of development. This study uses various cluster analyses to develop an optimal algorithm that can derive solar power plant locations on idle railway sites and, as a result, suggests 202 'actively recommended areas.' These results would help decision-makers make rational decisions from the viewpoint of simultaneously considering the economy and the environment.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.5
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• pp.298-305
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• 2014

In this study, a novel Randomly Shifted Certification Authority Authentication protocol was used in ad hoc networks to provide authentication by considering the MAC layer characteristics. The nodes achieve authentication through the use of public key certificates issued by a CA, which assures the certificate's ownership. As a part of providing key management, the active CA node transfers the image of the stored public keys to other idle CA nodes. Finally the current active CA randomly selects the ID of the available idle CA and shifts the CA ownership by transferring it. Revoking is done if any counterfeit or duplicate non CA node ID is found. Authentication and integrity is provided by preventing MAC control packets, and Enhanced Hash Message Authentication Code (EHMAC) can be used. Here EHMAC with various outputs is introduced in all control packets. When a node transmits a packet to a node with EHMAC, verification is conducted and the node replies with the transmitter address and EHMAC in the acknowledgement.

• Proceedings of the Korea Association of Information Systems Conference
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• 1996.11a
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• pp.199-204
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• 1996

It is discussed how to determine the home location of idle vehicles in an AGVS with a loop guide path in a way of maximizing the request-call response probabilities for all demand. Optimal home position is selected by solving the simultaneous equations easily. Static positioning strategy is analyzed in which a single home position is allocated to which every vehicle is routed whenever it becomes idle. The cases of unidirectional guidepath is considered only. We provide a numerical example to illustrate the search algorithm developed for the case and compare the searched optimal solutions with the others.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.681-685
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• 2004

Design of efficient Medium Access Control (MAC) protocols with both high throughput performances is a major focus in distributed contention-based MAC protocol research. In this paper, we propose an efficient contention-based MAC protocol for wireless Local Area Networks, namely, the Developed Collision Resolution (DCR) algorithm. This algorithm is developed based on the following innovative ideas: to speed up the collision resolution, we actively redistribute the backoff timers for all active nodes; to reduce the average number of idle slots, we use smaller contention window sizes for nodes with successful packet transmissions and reduce the backoff timers exponentially fast when a fixed number of consecutive idle slots are detected. We show that the proposed DCR algorithm provides high throughput performance and low latency in wireless LANs.