• 정보처리학회논문지A
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• 제14A권3호
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• pp.159-166
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• 2007

u-러닝(u-learning) 체제의 도입은, 원격교육을 지원하는 다양한 형태의 u-러닝 시스템 및 모형을 요구하며, 이에 따라 네트워크를 이용한 u-러닝 환경의 원격교육시스템에 대한 연구가 지속적으로 진행되어왔다. 하지만, 현재 운영되고 있는 대부분의 원격교육시스템은 교수자와 학습자간의 지속적인 쌍방향 상호작용 유지의 어려움, 시스템 구축을 위한 경제적 부담, 시스템 운영에 투입되는 교수자의 기술적 소양 부족 등 여러 문제점을 안고 있다. 이러한 문제점을 해결하기 위해서는, 교사의 접속 여부와 무관한 지속적인 학습 활동의 유지, 시스템 구축의 경제성 및 사용상의 편리성에 대한 고려가 선행되어야 한다. 이에 본 연구에서는, 이동성과 내재성 등의 u-러닝 개념을 포함하고, 가상 교수자(cyber tutor)의 결합에 의해 실제 교수자의 접속 상태와는 독립적으로 지속적인 교수-학습 과정을 지원하며, 사용자의 기술적, 경제적 부담의 제거가 가능한 지능형 u-러닝시스템을 개발하고, 그 적용 가능성을 검증하였다.

• 정보처리학회논문지C
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• 제19C권1호
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• pp.71-82
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• 2012

향후의 차세대 무선 네트워크(NGWN) 환경에서는 음성을 비롯한 모든 정보들이 ALL-IP 망에서 동작하게 될 것이며, 현재는 이러한 과도기로서 IP 네트워크에서 사용자로 하여금 끊김없는 서비스를 유지하기 위한 망의 중요성 및 이기종 네트워크 간의 핸드오프에 대한 중요성이 커지고 있다. 이에 본 논문에서는 NGWN에서 여러 기법 중 핸드오프 성능을 높일 수 있는 끊김없는 PMIPv6 기반의 프록시 모델을 이용한 SePH를 제안한다. SePH의 특징으로는 핸드오프 과정 중 탐색 과정을 줄임으로서 끊김없는 IP 기반의 이동성을 효율적으로 지원할 수 있다. 제안한 SePH 기법의 성능 평가는 현재 이동성 관리 프로토콜에 비해 처리량, 핸드오프 지연시간, 패킷손실 및 시그널링 오버헤드 등의 이동성 관리 측면에서 QoS 향상을 보여준다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.179-180
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• 2007

Single crystal $AgGaSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $420^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $AgGaSe_2$ source at $630^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $AgGaSe_2$ thin films measured with Hall effect by van der Pauw method are $4.05{\times}\;10^{16}/cm^3$, $139\;cm^2/V{\cdot}s$ at 293 K. respectively. The temperature dependence of the energy band gap of the $AgGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=1.9501\;eV\;-\;(8.79{\times}10^{-4}\;eV/K)T^2$/(T + 250 K). The crystal field and the spin-orbit splitting energies for the valence band of the $AgGaSe_2$ have been estimated to be 0.3132 eV and 0.3725 eV at 10 K, respectively, by means of the phcitocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}So$ definitely exists in the $\Gamma_5$ states of the valence band of the $AgGaSe_2$. The three photocurrent peaks observed at 10 K are ascribed to the $A_1$-, $B_1$-, and $C_1$-exciton peaks for n = 1.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1999년도 정기총회 및 춘계 공동 학술발표회
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• pp.149-156
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• 1999

In the United States (U.S.), the monitored natural attenuation (MNA) approach has been used as an alternative remedial option for organic and inorganic compounds retained in soil and dissolved in groundwater. The U.S. Environmental Protection Agency (EPA) defines the MNA as“in-situ naturally-occurring processes include biodegradation, diffusion, dilution, sorption, volatilization, and/or chemical and biochemical stabilization of contaminants and reduce contaminant toxicity, mobility or volume to the levels that are protective of human health and the environment”. The Department of Soil Environment. National Institute Environmental Research (NIER) is in the process for demonstrating the MNA approach as a potential remedial option for the BTEX contaminated site in Uiwang City. The project is charactering the research site in terms of the nature and extend of contamination, biological degradation rate, and geochemical and hydrological properties. The microbial-degradation rate and effectiveness of nutrient and redox supplements will be determined through laboratory batch and column tests. The geochemical process will be monitored for determining the concentration changes of chemical species involved in the electron transfer processes that include methanogenesis, sulfate and iron reduction, denitrification, and aerobic respiration. Through field works, critical soil and hydrogeologic parameters will be acquired to simulate the effects of dispersion, advection, sorption, and biodegradation on the fate and transport of the dissolved-phase BTEX plume using Bioplume III model. The objectives of this multi-years research project are (1) to evaluate the MNA approach using the BTEX contaminated site in Uiwang City, (2) to establish a standard protocol for future application of the approach, (3) to investigate applicability of the passive approach as a secondary treatment remedy after active treatments. In this presentation, the overall picture and philosophy behind the MNA approach will be reviewed. Detailed discussions of the site characterization/monitoring plans and risk-based decision-making processes for the demonstration site will be included.

• Nuclear Engineering and Technology
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• 제43권6호
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• pp.567-572
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• 2011

A sensitivity analysis of the methods used to evaluate the transport properties of a CdZnTe detector was performed using two different radiations (${\alpha}$ particle and gamma-ray) emitted from an $^{241}Am$ source. The mobility-lifetime products of the electron-hole pair in a planar CZT detector ($5{\times}5{\times}2\;mm^3$) were determined by fitting the peak position as a function of biased voltage data to the Hecht equation. To verify the accuracy of these products derived from ${\alpha}$ particles and low-energy gamma-rays, an energy spectrum considering the transport property of the CZT detector was simulated through a combination of the deposited energy and the charge collection efficiency at a specific position. It was found that the shaping time of the amplifier module significantly affects the determination of the (${\mu}{\tau}$) products; the ${\alpha}$ particle method was stabilized with an increase in the shaping time and was less sensitive to this change compared to when the gamma-ray method was used. In the case of the simulated energy spectrum with transport properties evaluated by the ${\alpha}$ particle method, the peak position and tail were slightly different from the measured result, whereas the energy spectrum derived from the low-energy gamma-ray was in good agreement with the experimental results. From these results, it was confirmed that low-energy gamma-rays are more useful when seeking to obtain the transport properties of carriers than ${\alpha}$ particles because the methods that use gamma-rays are less influenced by the surface condition of the CZT detector. Furthermore, the analysis system employed in this study, which was configured by a combination of Monte Carlo simulation and the Hecht model, is expected to be highly applicable to the study of the characteristics of CZT detectors.

• Molecules and Cells
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• 제23권3호
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• pp.398-404
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• 2007

Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) are involved in various pathophysiological processes such as inflammation and carcinogenesis. In a search for inhibitors of COX-2 and iNOS production we found that extracts of Stewartia koreana strongly inhibited NO and $PGE_2$ production in LPS-treated macrophage RAW 264.7 cells. We have now shown that the mRNA and protein levels of iNOS and COX-2 are reduced by the Stewartia koreana extract (SKE). SKE inhibited expression of an NF-${\kappa}B$ reporter gene in response to LPS, and gel mobility shift assays revealed that SKE reduced NF-${\kappa}B$ DNA-binding activity. The extract also inhibited LPS-induced phosphorylation of $I{\kappa}B-{\alpha}$ and nuclear translocation of p65. Administration of the extract reduced the symptoms of arthritis in a collagen-induced arthritic mouse model. These results indicate that Stewartia extracts contain potentially useful agents for preventing and treating inflammatory diseases.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권9호
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• pp.1492-1512
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• 2011

Due to multiple hops, mobility and time-varying channel, supporting delay sensitive real-time traffic in wireless local area network-based (WLAN) mesh networks is a challenging task. In particular for real-time traffic subject to medium access control (MAC) layer control overhead, such as preamble, carrier sense waiting time and the random backoff period, the performance of real-time flows will be degraded greatly. In order to support real-time traffic, an efficient adaptive packet scheduling (APS) scheme is proposed, which aims to improve the system performance by guaranteeing inter-class, intra-class service differentiation and adaptively adjusting the packet length. APS classifies incoming packets by the IEEE 802.11e access class and then queued into a suitable buffer queue. APS employs strict priority service discipline for resource allocation among different service classes to achieve inter-class fairness. By estimating the received signal to interference plus noise ratio (SINR) per bit and current link condition, APS is able to calculate the optimized packet length with bi-dimensional markov MAC model to improve system performance. To achieve the fairness of intra-class, APS also takes maximum tolerable packet delay, transmission requests, and average allocation transmission into consideration to allocate transmission opportunity to the corresponding traffic. Detailed simulation results and comparison with IEEE 802.11e enhanced distributed channel access (EDCA) scheme show that the proposed APS scheme is able to effectively provide inter-class and intra-class differentiate services and improve QoS for real-time traffic in terms of throughput, end-to-end delay, packet loss rate and fairness.

• 한국IT서비스학회지
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• 제14권4호
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• pp.171-184
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• 2015

Nowadays, mobile commerce is having an increasingly profound impact on our daily lives, and offer interesting and advantageous new services. Mobile payment is an emerging and important application of mobile commerce in smart work, enabling users to use their mobile devices (especially mobile phones) for paying goods and services wherever they go. The appearance of m-payment is expected to provide us a convenient and bright future to enjoy. That is the common trend on over the world, but in Vietnam, although the number of smart phone users has been increasing rapidly, the adoption of m-payment system still didn't succeed completely. The research reviewed literature regarding mobile payment services, analyzed the impact of customer characteristics and system characteristics on m-payment adoption in Vietnam. To analyze the adoption behaviors of m-payment users, m-payment research model which consists of three customer-characteristics (m-payment trust, personal innovativeness, m-payment knowledge) and four m-payment system characteristics (mobility, reachability, convenience, compatibility) were studied. The results indicate that perceived usefulness, trust, and compatibility are the important predictors to the intention to use m-payment. This study will assist m-payment services suppliers in implementing appropriate business models and service strategies to successfully attract customer to use m-payment in Vietnam, allowing managers to exert appropriate investment, time, and effort for m-payment system development in designing smart working.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.234-238
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• 2004

A stoichiometric mixture of evaporating materials for $CuInSe_2$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $CuInSe_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $620^{\circ}C$ and $410^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CuInSe_2$ single crystal thin films measured with Hall effect by van der Pauw method are $9.62{\times}10^{l6}\;cm^{-3}$ and $296\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuInSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;1.1851\;eV\;-\;(8.99{\times}10^{-4}\;eV/K)T^2/(T+153K)$. The crystal field and the spin-orbit splitting energies for the valence band of the $CuInSe_2$ have been estimated to be 0.0087 eV and 0.2329 eV at 10K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}_{so}$ definitely exists in the $\Gamma_6$ states of the valence band of the $CuInSe_2$. The three photocurrent peaks observed at 10K are ascribed to the $A_1-$, $B_1-$, and $C_1$-exciton peaks for n = 1.

• 한국정보통신학회논문지
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• 제12권7호
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• pp.1263-1270
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• 2008

현재 기존의 웹과 차별화를 의미하는 웹 2.0에 대한 관심이 높아져 가고 있다. 기존의 시스템이 클라이언트와 서버 모델에 기반을 둔 정적인 웹이 전형적이었다면, 웹 2.0은 웹이 근본적으로 변화하고 진화한다는 차원의 차세대 웹을 뜻한다. 본 논문에서는 웹 2.0규격하에서 쓰일 수 있는 RSS리더에 대한 모듈을 제안한다. 제안된 모듈은 Ajax를 이용하여 개발하였다 현재 쓰이는 RSS Feed가 브라우저에 따라 왜곡될 수 있는 부분을 보정하고 한글 및 제 3세계 언어의 인코딩 문제를 해결하였고, Ajax의 유동성 있는 프로그래밍을 통한 DragBox모듈과 RSS Feed의 자동 업데이트 모듈의 설계 및 개발을 통해 웹 2.0 기반상에서의 효과적인 콘텐츠의 활용을 위한 모듈을 개발하였다.