• Korean Journal of Construction Engineering and Management
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• v.5 no.5 s.21
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• pp.143-150
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• 2004

Nowaday, The tendency of complexity and extension of construction fields increase the need for efficient works managements like a construction management. Consequently, by the introduction of Decision-Making Theories, researches for improving construction field's efficiencies are actively performed. Fuzzy Analytical Hierarchy Process method is invented, so that describes a decision maker's ambiguous linguistic judgment with fuzzy numbers. but most of researches on Fuzzy-AHP use symmetric triangular fuzzy function for estimating each evaluation item with the consequence that exact judgments are impossible. those limits are caused by the point that employed fuzzy ranking methods can not support dissymmetric fuzzy numbers. In this research, we aims to overcome this problem with R.P.R(Relative Preference Ratio) method and suggest improved Fuzzy-AHP method which can use dissymmetric fuzzy triangular numbers.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2006.06a
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• pp.164-168
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• 2006

전력 공격은 암호화 연산 과정 중 발생하는 소비 전력의 파형을 측정하여 비밀 정보를 알아내는 공격 방식이다. 이러한 전력 공격에 대한 취약성을 막기 위하여 message blinding, exponent blinding과 같은 기법들이 적용되어 왔다. 본 고에서는 $ECC^{[1]}$암호화 연산 과정에서, r이 임의의 정수일 때, dP=(d-r)P+rP인 관계를 이용하는 exponent blinding기법$^{[2]}$에 대하여 언급하고, 위 기법을 전력 공격의 대응책으로 적용 시 적절히 구현되지 않으면 power attack에 대하여 매우 취약하다는 것을 보인다.

• The KIPS Transactions:PartA
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• v.13A no.2 s.99
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• pp.147-156
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• 2006

Recently, streaming service accounts for large part of internet traffic and it is becoming the most popular service. Because of P2P's scalability, P2P-based streaming system is proposed. There are frequent leave and join of a node. To overcome the group dynamics, Multiple Multicast Trees Methods were suggested. However, since they did not consider discrepancy in peers' capacity, it may cause the trees to be long and unstable. So we suggest Resilient Capacity-Aware Multicast Tree construction scheme (R-CAT) that promotes superior peer to upper position in the tree and construct more stable and short multicast trees. By simulation we can show that R-CAT cost more overhead packets for tree joining process, but it reduce the end-to-end delay of the resulting tree and the number of packets lost during the node joining and leaving processes much more than SplitStream.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.28-30
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• 2006

스트리밍 서비스는 인터넷 트래픽의 많은 부분을 차지할 정도로 인기 있는 서비스가 되었고, 확장성을 위해 P2P기반의 스트리밍 서비스가 제안되었다. P2P기반 스트리밍 환경은 빈번한 피어들의 떠남과 합류가 일어난다. 이러한 멀티캐스트 그룹의 변화에 대처하기 위해서 다중 멀티캐스트 트리가 제안되었다. 이는 중복성을 통해 멀티캐스트 그룹의 변화에 따른 영향을 줄였다. 하지만 노드의 능력 차이를 고려하지 않았기 때문에 트리가 길어지고, 불안정해질 수 있다. 이를 위해 본 논문은 노드의 능력을 고려한 내구적 멀티캐스트 트리 생성 기법(R-CAT)을 제시하여 우수 노드를 트리의 상층부에 위치시킴으로써 트리의 길이를 줄이고 트리 상층부의 안정화 문제를 해결할 수 있다. 또한 제시한 기법의 유효성을 증명하기 위해 기존의 SplitStream을 확장해서 R-CAT을 구현, 비교 검증한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.1
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• pp.45-54
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• 2019

The damage detection method using the extended Kalman filter(EKF) technique has been continuously used since EKF can estimation the responses of the damaged building structure and the stiffness of the structure. However, in the use of EKF, the requirement of setting the initial paramters P, Q, and R has caused the divergence and instability of the state vector, and various researches have been conducted to determine theses parameters. In this paper, adaptive extended Kalman filter(AEKF) method is proposed to solve the problem of setting the values of P, Q, and R, which are important parameters determining the convergence performance of the EKF state vector. By using the AEKF method proposed in this study, the P, Q, and R parameters are updated every k steps. The proposed algorithm is applied for the estimation of stiffness and the damage detection of 3-DOF problem. Based of the verification, it can be found that the selection process for the values of P, Q, and R can improve the convergence performance of EKF.

• Investigative Magnetic Resonance Imaging
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• v.18 no.1
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• pp.34-42
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• 2014

Purpose : To evaluate the correlation of lesion-to-normal ratio (LNR) of signal intensity from double inversion recovery MR imaging and total choline-containing compound (tCho) resonance from single voxel MR spectroscopy in breast cancers. Materials and Methods: Between August 2008 and December 2009, 28 patients who were diagnosed as breast cancer and had undergone both double inversion recovery (DIR) MR imaging and MR spectroscopy (MRS) were included in this study. The signal intensities of the lesion (L) and ipsilateral normal breast tissue (N) were measured in region of interest of each breast cancer in DIR and contrast enhance MR image (CE-T1WI) to calculate the LNR value for each technique. MRS was performed using single-voxel MR spectroscopy. The height, width and area of tCho resonance were compared with each LNR of DIR and CE-T1WI. We used Pearson's correlation coefficient(r) for correlation analysis and the significance level was p=0.05. Results: There was no statistically significant correlation between LNR of CE-T1WI and height (r=-0.322, p=0.094), width (r=-0.233, p=0.232) and area (r=-0.309, p=0.109) of MRS tCho. There was no statistically significant correlation between LNR of DIR and height (r=0.067, p=0.735), width (r=-0.287, p=0.139) and area (r=0.012, p=0.953) of MRS tCho, either. The Pearson's correlation coefficient was 0.186 between LNRs of CET1WI and DIR (p=0.344). Conclusion: There was no statistically significant correlation between LNR of DIR and relative amount of tCho resonance of MRS.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.270-275
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• 2000

In this study, heat transfer and Pressure drop characteristics for R-718 in the plate and shell heat exchanger (P&SHE) investigated experimentally. The plates are circular and welded into a stack which fits into a cylindrical shell in P&SHE. Although apparently very different from rectangular the compact brazed plate heat exchanger (CBE), the underlying flow passage structure through the P&SHE is the same as in the CBE. The R-718 between plate side and shell side was performed a counterflow heat exchange. Heat transfer characteristic of R-718 were measured for turbulent flow in P&SHE by using wilson plot technique. Heat transfer experiment Ivas performed in the $200{\leq}Re{\leq}500$ regime and Pressure drop experiment was performed in the $150{\leq}Re{\leq}1600$ regime. The purpose of this study is to investigate heat transfer and friction factor correlations for R-718 in P&SHE and to offer fundamental data for experiment

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.1
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• pp.85-91
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• 2004

In this study, we evaluated the crow's feet of 152 Korean women by using visual assessment established by our research group and mechanical assessment, Skin Visiometer SV 600. The volunteers were divided into 3 groups according to age; the group I of 30's was 43, the group II of 40's was 75, the group III of 50's was 34. The wrinkle score by visual assessment showed tendency to increase according to age and was statistically significant different among those three age groups (P 〈 0.05). But there was no significant difference between the left and the right of crow's feet. The 5 wrinkle parameters (RI, R2, R3, R4, R5) of mechanical assessment varied as age and the Rl, R4, and R5 showed statistically significant difference among three age groups (P 〈 0.05). However there was no significant difference between the left and the right of crow's feet. The volunteers were divided into 3 groups according to wrinkle score; (0-3 grade for group A, 4-6 grade for group B, 7-9 grade for group C). Only R4 and R5 showed significant difference between group A and group C (P 〈 0.05). It was suggested that visual scoring criteria applied in this study was related to R4 and R5 and was useful in investigating in fine wrinkles.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.97-99
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• 2004

ONS나 E-mail 혹은 Instant Messaging등 메시지 애플리케이션에서 서버-클라이언트 모델은 scalability에 의한 한계가 있다. 이러한 문제를 해결할 수 있는 대안은 Peer-to-Peer 기반 정근방식이다. 하지만 이러한 환경에서는 기존의 P2P 시스템에 높은 데이터의 지속성과 Bounded Look-up Latency를 효과적으로 지원하는 방안이 필수적이다. 본 논문에서는 Replication을 통하여 Look-up Latency를 줄이기 위한 하나의 방법으로 Distributed k-ary Replication(DkR)을 제안한다. DkR은 source node와 root node 사이에 multi-path를 유지하고 Look-up Locality 특성을 이용하여 Replica를 배치함으로써 효율적으로 Look-up latency를 줄이게 된다. 마지막으로 DkR의 Replication 효과를 시뮬레이션을 통해서 확인을 해 보았다.

• Journal of Korea Water Resources Association
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• v.45 no.9
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• pp.861-874
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• 2012

To fulfill applicability of Soil and Water Assessment Tool (SWAT) model, it is important that this model passes through a careful calibration and uncertainty analysis. In recent years, many researchers have come up with various uncertainty analysis techniques for SWAT model. To determine the differences and similarities of typical techniques, we applied three uncertainty analysis procedures to Chungju Dam watershed (6,581.1 $km^2$) of South Korea included in SWAT-Calibration Uncertainty Program (SWAT-CUP): Sequential Uncertainty FItting algorithm ver.2 (SUFI2), Generalized Likelihood Uncertainty Estimation (GLUE), Parameter Solution (ParaSol). As a result, there was no significant difference in the objective function values between SUFI2 and GLUE algorithms. However, ParaSol algorithm shows the worst objective functions, and considerable divergence was also showed in 95PPU bands with each other. The p-factor and r-factor appeared from 0.02 to 0.79 and 0.03 to 0.52 differences in streamflow respectively. In general, the ParaSol algorithm showed the lowest p-factor and r-factor, SUFI2 algorithm was the highest in the p-factor and r-factor. Therefore, in the SWAT model calibration and uncertainty analysis of the automatic methods, we suggest the calibration methods considering p-factor and r-factor. The p-factor means the percentage of observations covered by 95PPU (95 Percent Prediction Uncertainty) band, and r-factor is the average thickness of the 95PPU band.