• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1167-1170
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• 2006

웹 인프라와 P2P 기술 개념을 기반으로 연구되고 있는 데이터 그리드 컴퓨팅 환경에서 중요한 문제 중 하나는 거대한 데이터 자료 접근에 관한 이슈이다. 요청된 자원 공간을 확보하기위해 저장되어 있는 자원을 선택하는 '캐쉬 교체 정책' 연구는 많이 연구되어 왔으나, 상항을 미리 예측하거나 스택과 같은 추가적인 자원이 필요하다. 본 논문은 기존 연구의 문제점을 해결하고 요청된 파일에 대응되는 파일의 개수가 되도록 적게 하기위해 파일 크기를 고려한 캐쉬 교체 정책을 제안하고 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.91-93
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• 2003

그리드 및 P2P 컴퓨팅 시스템과 같이 이종 시스템으로 연결된 환경을 관리하기 위해서 사용되는 미들웨어 및 운영체제의 복잡도의 증가로 인해 시스템 관리 비용이 증가하였다. 따라서 본 연구에서는 시스템 관리 비용을 최소화할 수 있는 시스템 구조적 접근 방식을 채택한다. 이질 컴퓨팅 환경을 통합하기 위해 XML 기반 기술을 사용하여 사람의 개입을 최소화할 수 있는 방법에 대해 제안하며, 적용 사례를 통해 제안된 구조와 기법에 대한 검증을 수행한다.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.1_2
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• pp.64-72
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• 2001

이 논문은 행렬 탐색 방법을 이용하여 평면상의 η개의 점에 대한 모든 L$_{p}$, 1$\leq$P$\leq$$\infty$ 거리의 양방향 각도제한 근접 점 문제를 0(nlogn) 시간에 계산하는 알고리즘을 고안한다. 이 방법은 최적의 시간 복잡도를 가지며 궤적추적 법을 쓰지 않기 때문에 수치오차가 적으며 구현이 용이하고 실용적이다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.10a
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• pp.369-372
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• 2004

유비쿼터스 환경에서는 프라이버시에 민감한 다양한 정보가 수집되고 이들이 통제되지 않은 채 배포될 수 있기 때문에 프라이버시 보호가 필수적이다. 유비쿼터스 환경에서 프라이버스 보안을 위해 사용되는 대표적인 방법론의 하나인 익명(anonymity) 기반 기법에서는, 사용자가 새로운 서비스 영역에 참여할 때 가명(pseudonym)을 사용할 수 있도록 하여, 사용자의 신분을 노출시키지 않도록 하는 방법이다. 이 방법은 사용자의 신분을 보호하는데는 효과적이지만, 친구 찾기 서비스, 위험지역경보, P2P통신 등 ID 기반의 서비스를 제공하기 어렵게 하는 단점이 있다. 이 논문에서는 익명기반의 프라이버스 보호 기법을 사용하는 유비쿼터스 환경에서 ID 기반의 서비스를 제공할 수 있도록 하는 시스템 구조를 제안한다.

• Journal of Internet Computing and Services
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• v.23 no.3
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• pp.21-33
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• 2022

This paper is to suggest the secure secret sharing system in order to outstandingly reduce the damage caused by the leakage of the corporate secret. This research system is suggested as efficient P2P distributed system kept from the centrally controlled server scheme. Even the bitcoin circulation system is also based on P2P distribution scheme recenly. This research has designed the secure circulation of the secret shares produced by Threshold Shamir Secret Sharing scheme instead of the shares specified in the torrent file using the simple, highly scalable and fast transferring torrent P2P distribution structure and its protocol. In addition, this research has studied to apply both Shamir Threshold Secret Sharing scheme and the securely strong multiple user authentication based on Collaborative Threshold Autentication scheme. The secure transmission of secret data is protected as using the efficient symmetric encryption with the session secret key which is safely exchanged by the public key encryption. Also it is safer against the leakage because the secret key is effectively alive only for short lifetime like a session. Especially the characteristics of this proposed system is effectively to apply the threshold secret sharing scheme into efficient torrent P2P distributed system without modifying its architecture of the torrent system. In addition, this system guaranttes the confidentiality in distributing the secret file using the efficient symmetric encryption scheme, which the session key is securely exchanged using the public key encryption scheme. In this system, the devices to be taken out can be dynamically registered as an user. This scalability allows to apply the confidentiality and the authentication even to dynamically registerred users.

• Journal of applied mathematics & informatics
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• v.30 no.1_2
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• pp.101-109
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• 2012

In this paper, we present an algorithm for computing the number of points on the Jacobian varieties of one-dimensional family of genus 3 nonhyperelliptic curves over finite fields. We also provide the explicit formula of the characteristic polynomial of the Frobenius endomorphism of the Jacobian of $C:y^3=x^4+{\alpha}$ over a finite field $\mathbb{F}_p$ with $p{\equiv}1$ (mod 3) and $p{\neq}1$ (mod 4). Moreover, we give some implementation results using Gaudry-Schost method. A 162-bit order is computed in 97 s on a Pentium IV 2.13 GHz computer using our algorithm.

• Computational Structural Engineering
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• v.4 no.2
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• pp.77-85
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• 1991

A new finite element technology based on the p-version of E.F.M. is discussed with reference to its potential for application to stress intensity factor computations in linear elastic fracture mechanics, especially cracked cylindrical shells. It is shown that the p-version model is far better suited for computing the stress intensity factors than the conventional h-version models with the help of three test problems. The main advantage of this technology is that the accuracy of approximation can be established without mesh refinement or the use of special procedures such as crack-tip element and mixed variational approach.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.6
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• pp.17-28
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• 2002

XTR is a new method to represent elements of a subgroup of a multiplicative group of a finite field GF( $p^{6m}$) and it can be generalized to the field GF( $p^{6m}$)$^{[6,9]}$ This paper progress optimal extention fields for XTR among Galois fields GF ( $p^{6m}$) which can be aplied to XTR. In order to select such fields, we introduce a new notion of Generalized Opitimal Extention Fields(GOEFs) and suggest a condition of prime p, a defining polynomial of GF( $p^{2m}$) and a fast method of multiplication in GF( $p^{2m}$) to achieve fast finite field arithmetic in GF( $p^{2m}$). From our implementation results, GF( $p^{36}$ )longrightarrowGF( $p^{12}$ ) is the most efficient extension fields for XTR and computing Tr( $g^{n}$ ) given Tr(g) in GF( $p^{12}$ ) is on average more than twice faster than that of the XTR system on Pentium III/700MHz which has 32-bit architecture.$^{［6,10］/ ［6,10］/6,10］}$

• Physical Therapy Rehabilitation Science
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• v.13 no.2
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• pp.152-162
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• 2024

Objective: This study was conducted to analyze the effect of wearable Electromyography-controlled functional electrical stimulation (EMG-controlled FES) System on Gait Function and cardiopulmonary metabolic efficiency during walking in older adults. Design: Cross-section study Methods: Total 22 older adult participants suitable to selection criteria of this study participated in this study. The EMG-controlled FES System, which functions as a wearable physical activity assist FES system was used. All participations performed randomly assigned two conditions (Non-FES assist [NFA], FES assist [FA]) of walking. In all conditions, spatio-temporal parameters and kinematics and kinetics parameters during walking was collected via 3D motion capture system and 6 minutes walking test (6MWT) and metabolic cost during walking and stairs climbing was collected via a portable metabolic device (COSMED K5, COSMED Srl, Roma, Italy). Results: In Spatio-temporal parameters aspects, The EMG-controlled FES system significantly improved gait functions measurements of older adults with sarcopenia at walking in comparison to the NFA condition (P<0.05). Hip, knee and ankle joint range of motion increased at walking in FA condition compared to the NFA condition (P<0.05). In the FA condition, moment and ground reaction force was changed like normal gait during walking of older adults in comparison to the NFA condition (P<0.05). The EMG-controlled FES system significantly reduced net cardiopulmonary metabolic energy cost, net energy expenditure measurement at stairs climbing (P<0.05). Conclusions: This study demonstrated that EMG-controlled FES is a potentially useful gait-assist system for improving gait function by making joint range of motion and moment properly.

• Journal of IKEEE
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• v.24 no.1
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• pp.186-193
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• 2020

In this paper, we propose a multi-threading system to support reconfigurable hardware accelerators on Zynq SoC. We implement high-performance JPEG decoder with reconfigurable 2D IDCT hardware accelerators to achieve maximum performance available on the platform. In this system, up to four reconfigurable hardware accelerators synchronized with SW threads can be dynamically reconfigured to provide adaptive computing capabilities according to the given image resolution and the compression ratio. JPEG decoding is operated using images with resolutions 480p, 720p, 1080p at the compression ratio of 7:1-109:1. We show that significant performance improvements are achieved as the image resolution or the compression ratio increase. For 1080p resolution, the performance improvement is up to 79.11 times with throughput speed of 99 fps at the compression ratio 17:1.