• Journal of the Korea Society for Simulation
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• v.15 no.4
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• pp.97-105
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• 2006

Popular content stored within the Internet may be convenient to download via modern 3G connections, but costly due to a fee charged by telecommunication providers on the basis of the amount of data transferred. This paper presents a network in which several mobile devices, called the peers, cooperate to download their assigned portion of the content using a 3G connection in order to reduce the overall cost. Then, the peers exchange their assigned portion of the content with other peers via a wireless ad hoc network and the peers reconstruct the whole content using the exchanged portion. This paper focuses on the per-peer based distribution method, and presents the performance comparison with a similar method, called the per-packet distribution method. Both methods are designed to reduce packet collisions while content is exchanged. The simulation result indicates that the per-peer based method outperforms the per-packet based method, and approximately 90% of the telecommunication cost is saved with as few as 10 peers.

• Korean Journal of Environment and Ecology
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• v.22 no.4
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• pp.427-434
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• 2008

The studies of seven individuals of Asiatic black bears were carried out with radio telemetry from October 2004 to December 2006 in Jirisan National Park. They were attached radio-transmitter and calculated by the 95%MCP and fixed kernel method(95%, 50%). As a result, Mean annual home ranges for female and male asiatic black bears were 71.66$km^2$ and 90.20$km^2$. The seasonal home ranges were calculated 19.81$km^2$ for females and 33.47$km^2$ for males in spring, 30.48$km^2$ for females and 20.26$km^2$ for males in summer, 22.63$km^2$ for females and 23.23$km^2$ for males in autumn and 0.22$km^2$ for females and 0.78$km^2$ for males in winter(F=4.193, P<0.05). The degree of home range overlapped 38%, 12.5% among females, 22.4% among males. Mean elevation of seven bears was 744$\pm$236m in spring, 682$\pm$253m in summer, 937$\pm$218m in fall and 975$\pm$137m in winter(F=8.526, P<0.001). It is assumed that home range sizes and location were closely correlated to environmental characteristics of the habitats and the seasonal variation of home-range was related to distribution of food sources.

• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.405-413
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• 2000

This study was conducted to develop an on-line monitoring system for a forest hydrological environment and its meteorological condition, such as temperature, wind direction and speed, rainfall and water level on V-notch, electrical conductivity(EC), potential of hydrogen(PH) by the motor drive sensor unit and measurement with a single-chip microprocessor as controller. These results are summarized as follows ; 1. The monitoring system consists of a signal process unit, motor drive sensor unit, radio modem unit and power supply. 2. The motor drive sensor unit protects the sensor from swift current or freezing and can constantly maintain fixed water level during measurements. 3. This monitoring system can transfer the data by radio modem. Additionally, this system can monitor hydrological conditions in real time. 4. The hardware was made of several modules with an independent CPU. They can be mounted, removed, repaired and added to. Their function can be changed and expanded. 5. These are the result of an accuracy test, the values of temperature, EC and pH measured within an error range of ${\pm}0.2^{\circ}C$, ${\pm}1{\mu}S$ and ${\pm}0.1pH$ respectively. 6. This monitoring system proved to be able to measure various factors for a forest hydrological environment in various experimental stations.

• Journal of Digital Convergence
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• v.13 no.5
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• pp.213-218
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• 2015

In parallel with evolving information communication technology, M2M(Machine-to-Machine) industry has implemented multi-functional and high-performance systems, and made great strides with IoT(Internet of Things) and IoE(Internet of Everything). Authentication, confidentiality, anonymity, non-repudiation, data reliability, connectionless and traceability are prerequisites for communication security. Yet, the wireless transmission section in M2M communication is exposed to intruders' attacks. Any security issues attributable to M2M wireless communication protocols may lead to serious concerns including system faults, information leakage and privacy challenges. Therefore, mutual authentication and security are key components of protocol design. Recently, secure communication protocols have been regarded as highly important and explored as such. The present paper draws on hash function, random numbers, secret keys and session keys to design a secure communication protocol. Also, this paper tests the proposed protocol with a formal verification tool, Casper/FDR, to demonstrate its security against a range of intruders' attacks. In brief, the proposed protocol meets the security requirements, addressing the challenges without any problems.

• Journal of Digital Convergence
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• v.13 no.4
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• pp.387-393
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• 2015

The purpose of this study is investigating the effects of combination of policosanol intake and combined exercise to the defence mechanism and the changes of fat cell control hormones by analyzing the changes of inflammatory markers LDH and CPK, and Leptin when having policosanol intake and combined exercise together against obese women for 12 week. These groups are randomly assigned to the control group, policosanol intake group, combined exercise group and combined treatment group with 12 obese women in esch group and they performed muscular resistance exercise and an aerobic exercise which was walking twice a week. After 12 weeks the LDH showed significant differences(p<.01) at exercise period, and also showed the significant differences(p<.05) in the effect of the interaction between exercise period and group. The changes in Leptin showed significant differences(p<.001) at exercise period. In summary, carrying out together of the aerobic exercise, muscular resistance exercise or policosanol intake can be considered to have the beneficial effects to prevent various disease which caused by inflammatory maker and Leptin and it also increases its effects.

• Information and Communications Magazine
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• v.25 no.1
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• pp.44-51
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• 2008

국가사회기반구조의 중추신경계 역할을 수행하는 정보통신 인프라를 기반으로 개인의 사이버생활 일상화, 디지털경제로의 전환, 전자정부 구축이 가속화되고 있다. 또한 네트워크 통합과 정보통신 서비스의 융합 등을 통한 제2의 디지털 혁명으로 유비쿼터스사회가 도래하고 있다. 그러나 이와 더불어 정보보호 환경은 개별 시스템, 네트워크 보호에서 서비스와 이용자 보호로 그 중심이 급격히 옮겨져 그 범위가 크게 확대되고 있으며, 웜 바이러스와 해킹 기능의 결합으로 복합화(Blended), 악성화된 사이버공격이 증가하고 있다. 또한 그 전파경로가 이메일은 물론 PC의 공유폴더, P2P, 웹 등으로 확대됨으로써 피해범위는 유선단말에서 무선단말과 방송단말 등으로 확장되고 있다. 이처럼 시간과 장소에 상관없이 지식정보를 자유롭게 이용함으로써 편리하고 쾌적한 정보이용 환경을 누리게 하는 유비쿼터스 사회는, 그러나 동시에 예측 불가능한 위험이 곳곳에 산재한 '고도화된 정보위험사회'로의 진입을 의미한다. 이에 따라 새로운 위협이 상존하는 유비쿼터스 환경 하에서 안심하고 신뢰할 수 있는 새로운 정보보호 정책방향의 설정과 대응전략이 필요함은 주지의 사실이라고 할 수 있다. 이에 본고에서는 유비쿼터스 사회에서 나타나는 새로운 도전과 신규위협에 대해 살펴보고, 정보보호 3대 핵심 추진 방향을 비롯한 향후 대응전략과 이를 통한 안전한 미래 사회의 청사진을 제시하도록 한다.

• Journal of Digital Convergence
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• v.12 no.3
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• pp.227-235
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• 2014

Mobile virtualization is an approach to mobile device management in which two virtual platforms are installed on a single wireless device. A smartphone, a single wireless device, might have one virtual environment for business use and one for personal use. Mobile virtualization might also allow one device to run two different operating systems, allowing the same phone to run both RTOS and Android apps. In this paper, we propose the techniques to virtualize the cores of a multicore, allowing the reassign any number of vCPUs that are exposed to a OS to any subset of the pCPUs. And then we also propose the real-time scheduling method to assigning the vCPUs to the pCPU. Suggested technology in this paper solves problem that increases time of real-time process when interrupt are handled, and is able more to fast processing than previous algorithm.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.2
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• pp.117-130
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• 1999

In this paper, the performance of data communication function of military radio equipment P-999K is analyzed based on the standard CSMA/CA protocol which is DFWMAC standard protocol done by IEEE802.11 work group. Basic three standard protocols, i.e. Basic CSMA/CA, Stop & Wait ARQ and 4-Way Handshake CSMA/CA protocols are analyzed and compared with each other under the hidden terminal environment. The computer simulation is also done by using SIMSCRIPT II.5 which is popular software tool for an independent processing. The results show that p-persistent(with p=0.3) CSMA scheme is superior to non-persistent CSMA scheme with non-hidden terminal condition, but the performances of both schemes are almost same with hidden terminal situation. And the results of computer simulations are also showed that Basic CSMA/CA protocol is superior to the other protocols when the ratio of hidden terminals is below 10 % of total user population, however, with the above 20% hidden terminals environment and the higher offered traffic conditions the 4-Way Handshake CSMA/CA protocol shows the most superior performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.570-576
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• 2004

In this paper, we design the IFFT/FFT (Inverse fast Fourier Transform/Fast Fourier Transform) modules for IEEE 802.11a-1999, which is a standard of the High-speed Wireless LAN using the OFDM (Orthogonal Frequency Division Multiplexing). The designed IFFT/FFT is the 64-point FFT to be compatible with IEEE 802.11a and the pipelined architecture which needs neither serial-to-parallel nor parallel-to-serial converter. We compare four types of IFFT/FFT modules for the hardware complexity and operation : R22SDF (Radix-2 Single-path Delay feedback), the R2SDF (Radix-2 Single-path Delay feedback), R2SDF (Radix-4 Single-path Delay Feedback), and R4SDC (Radix-4 Single-path Delay Commutator). In order to minimize the error, we design the IFFT/FFT module to operate with additional decimal parts after butterfly operation. In case of the R22SDF, the IFFT/FFT module has 44,747 gate counts excluding RAMs and the minimized error rate as compared with other types. And we know that the R22SDF has a small hardware structure as compared with other types.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.450-466
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• 2014

This study compared and analyzed body composition, physical fitness, and physical self-concept between gifted students in mathematics and science attending Korea Science Academy (KSA) and non-gifted students attending traditional high schools. The KSA students were 117 males who entered the school in 2009. As a control group, a total of 117 non-gifted students were randomly selected from 5 cities. The results of covariate analysis taken 2 year interval, pretest (2009) and posttest (2010), indicated that gifted students were significantly taller (p<.05) than non-gifted students, and were lower in BMI (p<.05) and PBF (p<.001). There was no significant difference in physical fitness between gifted and non-gifted students. But non-gifted students have a significantly higher self-concept in physical appearance (p<.05) and physical strength (p<.05). The internal/external frame of reference model and the Big Fish Little Pond Effect (BFLPE) theory were supported. Especially, gifted students were significantly higher (p<.01) in endurance self-concept than non-gifted students. We have discussion this result as the future research subject whether it come from the characteristics of the gifted's tenacity at high level tasks.