• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6A
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• pp.791-802
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• 1999

This paper introduces a wireless multimedia CDMA system using a simulcasting method and configuring multiple radio links between a user and radio ports. The CDMA system with multiple links can support seamless and soft handoffs as well as port-diversity effect. We propose two transmission power control algorithms for the multiple links which support the required service quality. We perform simulations for the capacity of the proposed system. In the simulations, a system with nine ports is configured and simulated. For the uplink, as the number of the multiple links increases, the capacity also increases and immediately approaches to the theoretical upper limit. It is shown that four radio links are enough to achieve the theoretical maximum capacity. On the other hand, for the downlink, though it has the merit of soft and seamless handoff in the wireless ATM system, the capacity rather decreases as the increase of the number of the links due to the severe multiple interferences.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6B
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• pp.508-516
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• 2006

The explosive growth of wireless network users and the existence of various wireless services have demanded high rate throughput as well as user's QoS guarantees. Towards this, this paper proposes QoS-oriented subcarrier allocation scheme considering the QoS provisioning of multiple users, which is major requirement for wireless network design point of view. This paper introduces joint RR/K&H combined with M-LWDF(Modified Largest Weighted Delay First) scheme throughout observing statistical channel behavior and real time queuing analysis for appropriate resource allocation tightly connected to multiuser scheduling. Accordingly, the system throughput can be enhanced, and the QoS demanded for delay sensitive services can be satisfied. Furthermore, the proposed scheme is applied for OFDMA(Orthogonal Frequency Division Multiple Access) systems to allocate sub-carriers in optimal way. The simulation results verify plausible performances of proposed resource allocation scheme via showing superior effective capacity under time-varying physical-layer channel behaviors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1349-1358
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• 2009

Because of the limitation of supporting power, the current WSN(Wireless Sensor Network) Technologies whose one of the core attributes is low power consumption are the best solution for shipping container networking in stack environment such as on vessel. So it is effective to use the Wireless Sensor Network Technology. In this case, many nodes join in the network through a sink node because there are difficulties to get big money and efforts to set up a lot of sink node. It needs clustering-based proactive protocol to manage many nodes. But it shows low reliability because they have effect on radio frequency in metal obstacle environments(interference, distortion, reflection, and etc) like the intelligent container. In this paper, we proposed an improved Modified LEACH Protocol for stableness radio frequency environment. In the proposed protocol, we tried to join the network and derived stable topology composition after the measuring of link quality. Finally, we verified that the proposed protocol is composing more stable topology than previously protocol in metal obstacle environment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.122-129
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• 2009

In this paper, we have proposed the QoS (quality of services) control scheme which can adjust data transfer rates of the session participants in response to their radio channel conditions under the time-varying propagation radio environment. The outage probability is selected as the performance index in order to compare the performance of the proposed scheme with the conventional QoS control scheme. The outage probability of the single and multiple paths is mathematically derived here and its numerical results are investigated. The results show that the significant performance improvement can be obtained compared with the conventional scheme and also the diversity gain can improve the radio link outage as the degrees of the multipath diversity increases. Therefore the overall performance improvement in terms of the QoS of the outage probability can be significantly be achieved by applying the proposed scheme.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.8 s.350
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• pp.1-14
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• 2006

Multi-constraint QoS routing has been seen as crucial network property in the next generation optical Internet based on DWDM Networks. This paper proposes a new QoS routing algorithm based on flooding method, called bounded flooding routing (BFR) algorithm which can meet multi-constraint QoS requirements. Primarily, the BFR algorithm tries to reduce network overhead by accomplishing bounded-flooding to meet QoS requirements, and improve blocking probability and wavelength utilization. Also, as one effort to improve routing performance, we introduce a new concept, ripple count, which does not need any link-state information and computational process. For extensive analysis and simulation study, as a critical concern, in DWDM-based networks we deploy limited wavelength conversion capability within DWDM nodes. And the simulation results demonstrate that the BFR algorithm is superior to other predominant routing algorithms (both original flooding method and source-directed methods) in terms of blocking probability, wavelength channels required and overhead.

• The Journal of Advanced Prosthodontics
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• v.6 no.5
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• pp.333-345
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• 2014

PURPOSE. Bonding agents (BA) are the crucial weak link of composite restorations. Since the commercial materials' compositions are not disclosed, studies to formulize the optimum ratios of different components are of value. The aim of this study was to find a proper formula of BAs. MATERIALS AND METHODS. This explorative experimental in vitro study was composed of 4 different sets of extensive experiments. A commercial BA and 7 experimental formulas were compared in terms of degree of conversion (5 experimental formulas), shear bond strength, mode of failure, and microleakage (3 experimental formulas). Statistical analyses were performed (${\alpha}$=.05). The DC of selected formula was tested one year later. RESULTS. The two-way ANOVA indicated a significant difference between the shear bond strength (SBS) of two tissues (dentin vs. enamel, P=.0001) in a way that dentinal bonds were weaker. However, there was no difference between the four materials (P=.283). The adhesive mode of failure was predominant in all groups. No differences between the microleakage of the four materials at occlusal (P=.788) or gingival (P=.508) sites were detected (Kruskal-Wallis). The Mann-Whitney U test showed a significant difference between the microleakage of all materials (3 experimental formulas and a commercial material) together at the occlusal site versus the gingival site (P=.041). CONCLUSION. A formula with 62% bisphenol A-glycidyl methacrylate (Bis-GMA), 37% hydroxy ethyl methacrylate (HEMA), 0.3% camphorquinone (CQ), and 0.7% dimethyl-para-toluidine (DMPT) seems a proper formula for mass production. The microleakage and SBS might be respectively higher and lower on dentin compared to enamel.

• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.38-44
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• 2003

This study was performed to investigate the levels of fluoride (F), calcium (Ca), and magnesium (Mg) in water samples taken from five reservoirs or direct sources on a stream used for agricultural or domestic water in the Iksan and Wanjoo areas, Jeon-buk, Korea, and to find a possible link between Ca or Mg and fluoride in water sources in theses areas. The samples were collected by the recommendation methods of the World Health Organization and analyzed by the recommendations of the Japanese Standard Methods. Statistical analyses were performed by the analysis of variance and correlation analysis. The F levels in water samples wire 0.80~2.53 ppm. In four sampling sites the water fluoride levels exceeded 1 ppm. which if the recommended level for fluorosis/caries control. The Ca levels in water samples were 6.82~12.98 ppm, and the Mg levels were 0.30~1.97 ppm, which are lower compared with the natural levels of water sources previously reported by other investigators. This study showed a positive correlation between Ca and Mg (r= 0.8779. p<0.01) and a negative correlation between F and Ca (r=-0.6974, p<0.05) and also between F and Mg (r=-0.5581) in the water samples. However, the study did not find remarkable relationships in fluoride levels between sampling sites. These results support the fact that there were epidemics of dental fluorosis in this area. The lack of significant positive correlations in fluoride levels between sampling sites suggests that there may be some pathways for the transfer of the metal to the water through other environmental media besides the water course. Long-term epidemiological studies are needed on the relationship between high F together with low Ca and Mg levels in the water, and total human health in this community. There should alto be a long-term monitoring of the water quality in this area.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.13 no.2
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• pp.265-282
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• 2002

The purpose of this study is to investigate the principles of school library media center program and to finds out present level and future outlook of the program implementation in primary and middle school. The fundamental objective of school is learning and school library functions as a link to support this objective. Therefore quality of education must always be linked to the library media programs. A questionaire which consists of 13 questions covering school library media center operation was designed to final out how learning-teaching media program is being practiced in Korea. Based on this study, it is concluded that there is significant difference between present practice level and desired future-oriented practice. It is hoped that this study will help planners in formulating school library policy to achieve educational goal of the school.

• Journal of the Korean Society of Costume
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• v.60 no.6
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• pp.89-100
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• 2010

This study is intended to analyze current status of costume in the cultural industry and explore feasibility of integrating costume as important cultural contents in the digital era. Among the websites for contents as the cultural archetypes, some have strong foundations while others don't. First, as for various archetypal characters restored based on the Korean history, most of their clothes focus on shapes and colors but lack details. They should be produced in 3D to provide back views or textile patterns to users. To ease understanding of the history of costume, user-friendly services such as launch of a pop-up window when users click on specific contents in question should be available for detailed information. At least there should be a link to other related sites where users can conveniently find more details. Second, some sites have too much data under one subject, increasing complexity and undermining orderliness. As a result, it takes long time to identify the site map. In this case, it is required to rearrange the contents with Quick View by subject and related links for in-depth study. Third, each subject is important to develop the archetypes for a variety of purposes. Creation of design derived from them or their commercialization can be an example but these activities should not restrict imagination of users or degrade the value of the archetypes. Last, it is needed to adopt validation system to detect the needs for a regular update (renewal) and to fix errors. We found many servers whose operation is not stable in general. When these technical issues are addressed for stable operation, users will rely on the sites to utilize them for their purpose of developing the cultural archetypes. In conclusion, advancement of www.culturecontent.com is essential. Based on efficient management and operation of the system, the quality of contents would be increased and multi-faceted advertising campaigns focusing on needs should be launched, to promote application of the contents. This is the recommendation for the future of the cultural archetype industry in Korea.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.282-290
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• 2012

Today, home health care services needs a linkage plan of the customized home visiting health service in public health center, the medical institute home health care service, and home visiting nursing service based on long term care insurance for the elderly program which acknowledges the independence and professionalism of the home health care services while minimizing overlap through linking the projects. So, this study was performed by applying the Delphi technique, which draws agreement from professional opinion, to determine a method to link home health care services in Korea. The results of this study are as follows. Specialists agreed on 24 important items within the two domains of institutional linkage and medical linkage. And the significance of this study is as follows. The 24 items deduced for the approved nursing service linkage plan are expected to improve the home health care service business system, enhance the quality of home health care service, and bring increased satisfaction for service recipients. Also, seeking ways to minimize overlap in service can increase the effectiveness of health care and public health management at a national level. In addition, it is considered that this will ultimately reduce public medical costs as well as improve home health care service.