• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.2
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• pp.99-123
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• 1997

Performance analysis of NTT/BT protocol is investigated, which is a GFC (Generic Flow Control) ptotocol in ATM (Asynchronous Transfer Mode ) network and is based on cyclic reset mechanism. THe mean cell delay time is proposed as a performance measure of NTT/BT protocol. The mean cell delay time is defined as the duration from the instant the cell arrives at the transmission buffer until the cell is fully transmitted. The process of cell transmission can be described as a single server queueing modle with two dependent services. By utilizing this model, mean cell delay time is obtained and sensitivity of the factors such as window size and reset period is also analysed.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.714-718
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• 2009

3D reconstruction of a human face from an image sequence remains an important problem in computer vision. We propose a method, based on a factorization algorithm, that reconstructs a 3D face model from short image sequences exhibiting rotational motion. Factorization algorithms can recover structure and motion simultaneously from one image sequence, but they usually require that all feature points be well tracked. Under rotational motion, however, feature tracking often fails due to occlusion and frame out of features. Additionally, the paucity of images may make feature tracking more difficult or decrease reconstruction accuracy. The proposed 3D reconstruction approach can handle short image sequences exhibiting rotational motion wherein feature points are likely to be missing. We implement the proposal as a reconstruction method; it employs image sequence division and a feature tracking method that uses Active Appearance Models to avoid the failure of feature tracking. Experiments conducted on an image sequence of a human face demonstrate the effectiveness of the proposed method.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.45-47
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• 2007

주강소재 보수용접부의 품질 및 용접생산성 향상을 위해 기존 용접후열처리 조건(이하 PWHT)을 모재에 적용하는 품질열처리(이하 NTT)로의 대체 및 반자동 FCAW 용접방법의 적용 가능성을 확인하기 위해 상온 및 고온 물성평가(고온인장강도, 크리프 파단강도)를 수행한 결과, 제작 공정 측면에서 FCAW의 적용이 가능한 것으로 확인되었다. 또한 PWHT 대신 NTT를 적용함으로서 용접방법별 물성 편차가 줄어드는 NTT 열처리의 긍정적 효과가 확인되어, 궁극적으로 기존 PWHT 및 NTT 모두 적용이 가능한 것으로 확인되었다.

• ETRI Journal
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• v.4 no.2
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• pp.51-60
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• 1982

본 번역문은, 최근 NTT에서 추진하고 있는 INS에 관해, 알기쉽게 서술된 NTT 내부 문서(1981년 9월 NTT부총재가 직원들에게 배부한것)를 편역한 것이다. INS를 설명하기위해, 지금까지의 전기통신 서비스 변천과정을 소개하면서 거기에서 일어난 문제점들을 하나하나 제기하고 있으며. 그 해결을 위해 디지탈화를 해야하며 요금체계의 일원화, 네트워크의 통합등을 이룩해야만 한다고 주장하고 있다. 또한. INS를 실현하는 구체적인 방향등을 얻기위한 시범적인 모델 시스템 구축의 필요성과 계획을 소개하고. 사회적으로 파급되는 INS의 커다란 영향에 관해서도 소개하고있다. 마지막부분에서 NTT직원들의. INS실현을 성공케 하기위한, 정신적인 자세등에 대해 당부하는 부분도 주목할 만하며, 특히 일본 NTT의 거대화와 독점성에서의 문제 때문에 거론되고있는 영업부분의 일부개방, 부분적인 업무분리및 민영화 문제등에 유연하게 대처해 나가야 한다고 역설 하는 부분등은 여러 뜻에서 흥미 있다고 보여진다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1999.06a
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• pp.23.1-28
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• 1999

InterSpaceTM is an advanced networked virtual reality system that presents shared three-dimensional computer graphics (CG) worlds via the Internet where multiple users can enjoy synchronous communications with voice, video and text. Users can control their avatars as a surrogate interface. In InterSpace users can walk around and interact with other people and interact with contents. In this paper, we describe the function-distributed architecture used in InterSpace. The architecture enables flexible configuration of server functions and load distribution. It also allows users to select media and client PCs to switch servers dynamically.

• Digital Contents
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• no.6 s.97
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• pp.80-81
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• 2001

3세대 이동통신으로 알려져 있는 IMT-2000사업이 당초보다 늦어질 전망이다. 이는 NTT 도코모가 3세대 이동통신 서비스를 4개월 연기 방침을 발표함에 따른 것이다. NTT 도코모는 세계최초로 3세대(IMT-2000) 이동통신서비스를 제공할 업체로 주목을 받아 왔다. 특히 동기식과 비동기식간의 표준경쟁이 가속화되고 있는 상황에서 NTT도코모의 비동기식 방식의 성공 가늠자로 인식되어 왔다.

• Journal of Life Science
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• v.13 no.4
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• pp.457-462
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• 2003

Houttuynia Cordata thunb has been used as folk medicine for analgesics, beriberi, edema, hepatitis and icterus etc. We investigated, the effects of Houttuynia Cordata thunb administration on protective in liver of 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD) treated rats. Seven days after the injection of TCDD(1${\mu}g$/kg), Houttuynia Cordata thunb (200mg/kg) was administered into rats intraperitoneally for four weeks. We examined the antioxidative enzymatic activity by measuring the level of GOT, GPT in serum and MDA, GSH, GSSG, GPx, SOD and Catalase in liver tissue of rats. GOT activity of Houttuynia Cordata thunb and TCDD administered group(HTT) showed 49.00% of inhibitive effect compared to TCDD-treated abnormal group(TTA). GPT level of HTT group was decreased to the level of Non TCDD-treated group(NTT). MDA content in the TTA group was 1.27 times increased compared to NTT group. HTT group was inhibited by 69.53% compared to TTA group. GSH contents in HTT group was 1.91 times increased compared to TTA group. GSSG contents in HTT group was 46.72% decreased compared to TTA group. SOD and Catalase in TTA group were lower than in NTT group, but SOD and Catalase in HTT group were increased by 82% and 55.45% respectively compared to TTA group.

• ETRI Journal
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• v.26 no.5
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• pp.375-383
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• 2004

This paper proposes a common interleaving method associated with independent channel-encoding among transmitter antenna branches in orthogonal frequency and code division multiplexing based on multiple-input multiple-output (MIMO) multiplexing to achieve an extremely high throughput such as 1 Gbps using a 100 MHz bandwidth. This paper also investigates the average packet error rate performance as a function of the average received signal energy per bit-to-background noise power spectrum density ratio $(E_b/N_0)$. We found that the loss in the required average received $E_b/N_0$ of the proposed method is only within approximately 0.3 dB in up to a 12-path Rayleigh fading channel, using 16QAM and Turbo coding with a coding rate of 5/6. We also clarify that even for a large fading correlation among antenna branches, 1 Gbps is still possible by increasing the transmission power. Therefore, the proposed method reduces the processing rate to 1/4 in the turbo decoder with only a slight loss in the required average received $E_b/N_0$.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.1
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• pp.33-38
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• 2015

In this study, flat-type photocatalytic reaction system is applied to reduce toxic hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) in aqueous solution under UV irradiation. To overcome the limitation of conventional photocatalysis, a novel approach toward photocatalytic system for reduction of hexavalent chromium including nanotubular $TiO_2$ (NTT) on two kinds of titanium substrates (foil and mesh) were established. In addition, modified Ti substrates were prepared by bending treatment to increase reaction efficiency of Cr(VI) in the flat-type photocatalytic reactor. For the fabrication of NTT on Ti substrates, Ti foil and mesh was anodized with mixed electrolytes ($NH_4F-H_2O-C_2H_6O_2$) and then annealed in ambient oxygen. The prepared NTT arrays were uniformly grown on two Ti substrates and surface property measurements were performed through SEM and XRD. Hydraulic retention time(HRT) and substrate type were significantly affected the Cr(VI) reduction. Hence, the photocatalytic Cr(VI) reduction was observed to be highest up to 95% at bended(modified) Ti mesh and lowest HRT. Especially, Ti mesh was more effective as NTT substrate in this research.

• Journal of IKEEE
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• v.25 no.1
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• pp.88-94
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• 2021

Public-key cryptographic algorithms such as RSA and ECC, which are currently in use, have used mathematical problems that would take a long time to calculate with current computers for encryption. But those algorithms can be easily broken by the Shor algorithm using the quantum computer. Lattice-based cryptography is proposed as new public-key encryption for the post-quantum era. This cryptographic algorithm is performed in the Polynomial Ring, and polynomial multiplication requires the most processing time. Therefore, a hardware model module is needed to calculate polynomial multiplication faster. Number Theoretic Transform, which called NTT, is the FFT performed in the finite field. The logic verification was performed using HDL, and the proposed design at the transistor level using Hspice was compared and analyzed to see how much improvement in delay time and power consumption was achieved. In the proposed design, the average delay was improved by 30% and the power consumption was reduced by more than 8%.