• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7A
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• pp.528-534
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• 2012

In order to achieve high capacity and reliable link quality of the overlay convergent networks with the cognitive networking based on the advanced capability of the mobile terminal, a Distributed Wireless Communication System (DWCS) can provide the capability of enhancing the link quality. This paper has considered virtual cell: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on radio resource monitering. The considered system constructs DVC for multi-user high-rate data transmission, and the DWCS system exploits space-time trellis codes i.e., STTC to improve a spectral efficiency. The effects of imperfect CSI(channel state information) on the system performance has also been investigated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7A
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• pp.440-450
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• 2003

The reverse link of a spectrally overlaid macrocell/microcell cellular CDMA system supporting multimedia traffic is characterized in terms of the required signal power, interference, and capacity. Several narrowband subsystems are overlaid with a wideband subsystem in macrocells, while a single wideband subsystem is operated in a microcell with the same spectrum as the macrocell wideband subsystem. Using a typical propagation model the reverse link signal power and interference are characterized as the relative user signal power and the cross-tier interference factors between the macrocell and the microcell. The reverse link capacity of the overlay system is then analyzed. Analytical results show that the dominant parameters affecting the system performance are the spectral overlay ratio and the distance between the microcell and macrocell base stations. In particular, when the distance equals a half of macrocell radius, optimum performance can be achieved by minimizing the cross-tier interference factors. These results can be applied to CDMA multimedia network planning in heavily populated traffic areas.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.7
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• pp.32-38
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• 2009

In this paper, we consider the overlaid system of single frequency network broadcast service and cellular-based unicast data service. In general, broadcast service and unicast data service were considered as a separate services so that different frequency resources have been allocated for each. As the frequency resource get more expensive, however, there were some efforts to provide both the broadcast and unicast service over the same frequency resource by employing the so-called superposition coding. In fact, such an service overlay system has already been accepted as a standards in 3GPP long-term evolution (LTE). In this paper, we specifically investigate such overlay system within 3GPP framework and evaluate their performance in terms of BC coverage and UC data throughput.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06c
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• pp.350-352
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• 2012

최근 의료 분야 소프트웨어가 발전함에 따라 3차원 가상 모델을 이용한 의료 소프트웨어의 개발도 꾸준히 증가하는 추세이다. 치열 교정 분야는 이러한 3차원 가상 모델을 적용할 수 있는 분야 중 하나이다. 치열교정 분야에서는 3차원 가상 모델을 이용하여 부정 교합 환자의 치료 초기부터 끝까지 여러 단계의 치아이동 과정을 제공한다. 치아 이동의 각 단계별로 Stereolithographic Model이 만들어지는데, 이는 투명하고 얇은 Overlay 장치를 제작하는 기초가 된다. 투명한 재질의 Overlay 장치는 심미적이고 사용이 간편하여 많은 환자들이 선호하고 있다. Overlay 장치를 제작하는 시스템을 구축한 회사로는 Invisalign System이 가장 대표적이다. Invisalign System은 미국에 본사를 둔 회사로 한국에 지사를 두고 적극적인 마케팅을 통해 3D 치열 교정 분야의 국내시장을 거의 독점하고 있다. 독점적이다 보니 비용이 다른 교정 치료보다 2배 가까이 들고 있지만, 현재 한국에서는 개발이 적극적으로 이루어지지 않는 실정이다. 이에 본 논문에서는 환자 치아의 정확하고 과학적인 진단자료를 얻어 높은 치료비용에 대한 개선과 치료 전 과정에 대한 시뮬레이션 및 Stereolithographic Model을 미리 환자에게 제공하여 만족도를 높일 수 있는 3D치열 교정 시스템을 제안한다.

• The KIPS Transactions:PartC
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• v.14C no.1 s.111
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• pp.81-86
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• 2007

New multimedia services over the cellular/WLAN overlay networks require different Quality of Service (QoS). Therefore, efficient network management system is necessary in order to provide QoS sensitive multimedia services while enhancing network performance. In this paper, we propose a new online network management scheme that implements bandwidth reservation, congestion and transmission control strategies. Our online approach to network management exhibits dynamic adaptability, flexibility, and responsiveness to the current traffic conditions in multimedia overlay networks. Simulation results indicate the superior performance of our proposed scheme to strike the appropriate performance balance between contradictory QoS requirements under widely varying diverse traffic loads.

• Journal of the Korea Society of Computer and Information
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• v.13 no.6
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• pp.233-241
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• 2008

The overlay multicast that has been recently presented as an alternative for the IP multicast needs scheduling method that can apply the system resource and the network bandwidth for the many users. We propose a efficient overlay multicasting network policy for multimedia services with composite stream service topology. And in order to evaluate the ability of the proposed scheme's performance, We test the performance of multi_casting nodes with RTT values, the bandwidth attrition rate for building the network topology and MOR effects with Overcast[5] The result of simulation shows improves about $8{\sim}20%$ of performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1614-1620
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• 2009

The overlay multicast that has been recently presented as an alternative for the IP multicast has been getting much persuasion by the system resource and the network bandwidth and the advancement of the network cost. we propose a overlay multi_casting network policy for efficient multimedia services with P2P join scheduling. In order to evaluate the performance of proposed scheme, We test the performance of multi_casting nodes with average join count, the maximum guaranteed waiting time and buffer starvation ratio with similar techniques. The result of simulation shows improved about 15${\sim}$20% of performance.

• Journal of Environmental Science International
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• v.13 no.6
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• pp.489-495
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• 2004

The purpose of this research is to apply GIS(Geographic Information System) for the road simulation and find some benefits analysis for the design processes. The northern Jeju island was selected as a case study. The 1/5,000 digital map and GIS technique were used for optimum road design of the island based on Arc View software. Using this software we can get an overlay map by combination of hill shade map, slope map, aspect map, and building buffer map. Based on the overlay map, we designed the optimum road line and performed three dimensional simulation. From the results, we found that the developed three dimensional road simulation technique using GIS technique that was very useful tool to estimate the reasonable road design before the real road construction works.

• Journal of Industrial Technology
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• v.26 no.B
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• pp.199-206
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• 2006

Internet telephony provides voice communication services with added flexibility for multimedia extension at a lower cost compared to traditional telephone systems. We implemented an internet telephony system as an overlay network without a centralized server, using a distributed hash table (DHT). Compared to the current server-based internet telephony system, our system is fault-tolerant, scalable, and can be flexible extended to various services and advanced to integrated service. To demonstrate the high flexibility of our DHT-based internet telephony system, we made our system cooperate with web servers. Web users can check up others' online stales and establish voice communication sessions to online users at a mouse click. This technology can be applied to more complex services such as multimedia messaging or video conference service.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.7
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• pp.32-39
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• 1999

Digital signal processor (DSP) is used to obtain the peak value and the time difference of ultrasonic signals, to make digital filter, and to derive mathematical transformation from analog circuit. In this study, C-scan system and control program have been developed to high speed data acquisition. This system consists of signal processing parts (DSP, oscilloscope, pulser/receiver, digitizer), scanner, and control program. The developed system has been applied to a practical ultrasonic testing in overlay weld, and demonstrated high speed with precision