• 한국정보통신학회논문지
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• 제2권4호
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• pp.559-573
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• 1998

정보통신 표준화 기구들은 최근 동 분야가 국가 및 시장 경쟁력제고에 있어 전략적 수단으로 부상됨에 따라 더 많은 새롭고 복잡한 표준들을 보다 짧은 시간 내에 개발해야 한다는 문제에 직면하고 있으며, 이러한 문제 의 해결을 위해 이들은 표준개발절차의 많은 부분들을 전자화 시킨 소위 전자적 표준개발시스템 혹은 전자적 문서처리시스템의 구현을 꾀하고 있다. 본 논문에서는 이러한 정보통신분야의 환경변화에 효율적으로 대처하기 위해 국내 표준화 환경 및 표준화 순기(표준(안)연구개발표준(안)제안의견수렴표준화위원회 승인표준(안)확정)에 따른 Workflow기반 표준(안) 개발 환경을 WWW상에서 설계 구현한 표준정보유통망(SICN : Standards Information Cooperation Network) 시스템을 소개한다 구현된 온라인 표준개발 시스템은 기존의 인터라넷(Intranet)기반의 시스템과는 달리 개념적으로 인터넷의 제3물결이라 할 수 있는 엑스트라넷(Extranet) 개념의 Workflow 기반 시스템이라 할 수 있으며, 이는 향후 '가 상 표준 개발망(VSDN : Virtual Standards Development Network)'으로 확장 구현될 예정이다.

• 국제초고층학회논문집
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• 제5권4호
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• pp.251-262
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• 2016

Tall Buildings have been one of the most prominent symbols of economic growth for nearly a century. Yet, in the aftermath of the tragedies of September 11, "signature" Tall buildings have become the focus of much debate. The structural systems today are undergoing a major evolution to address the ability of providing flexibility in the design and use of the building together with sustainability (Green) and cost-effective system. This paper describes a new invented structural system, evolutionary structural analysis and design of Tall buildings, which involves the entire analysis process, including conceptual and design stages and comparison with the existing Tall building. This study presents an new innovative structural system, Beehive (Hexagrid), for Tall buildings. The final results are achieved by modeling an 80 story Tall building with the optimized angle and topology of hexagon members by using a computer analysis, ETABS finite element analysis. The objective function of this system is to use one structural system in order to both maximize Eigen frequency for resisting dynamic responses and minimize mean compliance for static responses. Finite element analysis is carried out by using standardized materials. Optimal Hexagrid topologies with the highest stiffness are finally determined to resist both static and dynamic behaviors. Holistic design integration approaches between structures and facades to save energy for environmental control are studied. Innovative design ideas to control structural motion as well as to utilize that motion to harness energy are discussed. Considering abundant emergence of tall buildings all over the world in recent years, the importance of the studies presented in this paper cannot be overemphasized for constructing more sustainable built environments.

• 디지털콘텐츠학회 논문지
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• 제19권2호
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• pp.363-370
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• 2018

최근 랜섬웨어 탐지는 디지털 콘텐츠 보호를 위한 컴퓨터 보안 분야에서 중요한 주요한 이슈가 되고 있다. 그러나 불행하게도 현재 시그니쳐 기반이나 정적 탐지 모델의 경우 압축 및 암호화 등의 기법을 이용하여 탐지를 피해갈 수 있다. 이를 극복하기 위해 본 논문에서는 RF, SVM, SL, NB 알고리즘 같은 데이터 마이닝 기법을 이용한 다이나믹 랜섬웨어 탐지 시스템을 제안하였다. 이 기법은 실제 소프트웨어를 구동 시켜 동작 행위를 추출해 API 호출 흐름 그래프를 만들고 그 특징을 분석에 이용하였다. 그 후 데이터 정규화, 특징 선택 작업을 진행하였다. 우리는 이러한 분석과정을 더욱더 개선 시켰다. 마지막으로 데이터 마이닝 알고리즘을 적용시켜 랜섬웨어인지를 판별하였다. 제안한 알고리즘의 성능 측정을 위해 더 적합한 추가 샘플 랜섬웨어 데이터를 수집하여 실험하였고 탐지성능이 향상되었음을 보여주었다.

• Structural Engineering and Mechanics
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• 제78권5호
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• pp.599-610
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• 2021

Early detection of small concrete crack or reinforcement corrosion is necessary for Structural Health Monitoring (SHM). Global vibration based methods are advantageous over local methods because of simple equipment installation and cost efficiency. Among vibration based techniques, FRF based methods are preferred over modal based methods. In this study, a new coupled method using frequency response function (FRF) and proper orthogonal modes (POM) is proposed by using the dynamic characteristic of a damaged beam. For the numerical simulation, wave finite element (WFE), coupled with traditional finite element (FE) method is used for effectively incorporating the damage related information and faster computation. As reported in literature, hybrid combination of wave function based wave finite element method and shape function based finite element method can addresses the mid frequency modelling difficulty as it utilises the advantages of both the methods. It also reduces the dynamic matrix dimension. The algorithms are implemented on a three-dimensional reinforced concrete beam. Damage is modelled and studied for two scenarios, i.e., crack in concrete and rebar corrosion. Single and multiple damage locations with different damage length are also considered. The proposed methodology is found to be very sensitive to both single- and multiple- damage while being computationally efficient at the same time. It is observed that the detection of damage due to corrosion is more challenging than that of concrete crack. The similarity index obtained from the damage parameters shows that it can be a very effective indicator for appropriately indicating initiation of damage in concrete structure in the form of spread corrosion or invisible crack.

• Korean Journal of Radiology
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• 제22권7호
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• pp.1021-1033
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• 2021

Objective: To assess the expression of vascular normalization genes in different molecular subtypes of breast cancer and to determine whether molecular subtypes with a higher vascular normalization gene expression can be identified using dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI). Materials and Methods: This prospective study evaluated 306 female (mean age ± standard deviation, 50 ± 10 years), recruited between January 2014 and August 2017, who had de novo breast cancer larger than 1 cm in diameter (308 tumors). DCE MRI followed by IVIM DWI studies using 11 different b-values (0 to 1200 s/mm²) were performed on a 1.5T MRI system. The Tofts model and segmented biexponential IVIM analysis were used. For each tumor, the molecular subtype (according to six [I-VI] subtypes and PAM50 subtypes), expression profile of genes for vascular normalization, pericytes, and normal vascular signatures were determined using freshly frozen tissue. Statistical associations between imaging parameters and molecular subtypes were examined using logistic regression or linear regression with a significance level of p = 0.05. Results: Breast cancer subtypes III and VI and PAM50 subtypes luminal A and normal-like exhibited a higher expression of genes for vascular normalization, pericyte markers, and normal vessel function signature (p < 0.001 for all) compared to other subtypes. Subtypes III and VI and PAM50 subtypes luminal A and normal-like, versus the remaining subtypes, showed significant associations with K^trans, k_ep, v_p, and IAUGC_BN90 on DEC MRI, with relatively smaller values in the former. The subtype grouping was significantly associated with D, with relatively less restricted diffusion in subtypes III and VI and PAM50 subtypes luminal A and normal-like. Conclusion: DCE MRI and IVIM parameters may identify molecular subtypes of breast cancers with a different vascular normalization gene expression.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.63.2-63.2
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• 2015

Controlling and sensing spin states of magnetic molecules such as metallo-porphyrins at the single molecule level is essential for spintronic molecular device applications. Axial coordinations of diatomic molecules to metallo-porphyrins also play key roles in dynamic processes of biological functions such as blood pressure control and immune response. However, probing such reactions at the single molecule level to understand their physical mechanisms has been rarely performed. Here we present on our single molecule association and dissociation experiments between diatomic and metallo-porphyrin molecules on Au(111) describing its adsorption structures, spin states, and dissociation mechanisms. We observed bright ring shapes in NO adsorbed metallo-porphyrin compelxes and explained them by considering tilted binding and precession motion of NO. Before NO exposure, Co-porphryin showed a clear zero-bias peak in scanning tunneling spectroscopy, a signature of Kondo effect in STS, whereas after NO exposures it formed a molecular complex, NO-Co-porphyrin, that did not show any zero-bias feature implying that the Kondo effect was switched off by binding of NO. Under tunneling junctions of scanning tunneling microscope, both positive and negative energy pulses. From the observed power law relations between dissociation rate and tunneling current, we argue that the dissociations were inelastically induced with molecular orbital resonances. Our study shows that single molecule association and dissociation can be used to probe spin states and reaction mechanisms in a variety of axial coordination between small molecules and metallo-porphyrins.

• 한국항공우주학회지
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• 제38권1호
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• pp.22-28
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• 2010

복합재 구조물의 손상을 탐지하기위해 비파괴 검사법이 폭넓게 사용되고 있다. 태핑시험은 복합적층판의 손상을 탐지하는데 가장 일반적으로 사용하는 방법이다. 이 방법은 가벼운 해머 같은 장치를 이용하여 검사부위를 두드리고, 국부적인 강성변화를 이용하여 구조물의 손상을 평가한다. 진동신호의 변화는 동적인 접촉하중을 측정하여 탐지할 수 있다. 본 연구에서는 구조물에 층간분리나 표면균열 등의 손상이 존재하는 경우 태핑 시 충격하중이력의 특성이 변하는 것을 보였다. 그리고 손상의 영향을 검토하기위해 균열이 있는 복합재 로터블레이드에 대한 충격해석을 수행하였다.

• 한국전산유체공학회지
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• 제18권1호
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• pp.13-21
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• 2013

Cavitating flow is usually formed on the surface of a high speed underwater object. When a object moves near a free surface at very high speed, the cavity signature becomes one of the major factors to be overcome by sensors of military satellite. The present work was to study the free surface effect on the ventilated cavitation. The governing equations were Navier-Stokes equations based on a homogeneous mixture model. The multiphase flow solver used an implicit preconditioning method in the curvilinear coordinate system. The cavitation model used here was the one first presented by Merkle et al.(2006) and redeveloped by Park & Ha(2009). Computations considered the free surface effects were carried out with a NACA0012 hydrofoil and the corresponding results were compared with the experimental data to have a good agreement. Calculations were then performed considering the ventilated cavitation, including the effect of non-condensable gas under the free surface effects.

• 한국컴퓨터정보학회논문지
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• 제13권3호
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• pp.123-130
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• 2008

P2P 응용 프로그램들은 일반적으로 방화벽과 같은 보호시스템을 피하기 위해, 동적인 포트 번호 등을 사용하기도 한다. 그에 따라 포트 기반의 방법과 시그너처, 패킷 페이로드의 전수 검사 등을 통해 트래픽 식별을 하는 많은 방법론을 이용하지만, 여전히 정성적인 면과 정량적인 면을 만족시키지 못하고 있다. 따라서 이 논문에서는 P2P가 기본적으로 가지는 프로토콜의 성격을 이용하여 P2P의 트래픽 특성들을 분석하고 플로우 단위로 트래픽을 수집한 후, SVM을 이용하여 P2P 트래픽을 식별할 수 있는 방법론을 제안하고자 한다.

• Journal of Information Processing Systems
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• 제7권1호
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• pp.173-186
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• 2011

Due to the disadvantages of signature-based computer virus detection techniques, behavior-based detection methods have developed rapidly in recent years. However, current popular behavior-based detection methods only take API call sequences as program behavior features and the difference between API calls in the detection is not taken into consideration. This paper divides virus behaviors into separate function modules by introducing DLLs into detection. APIs in different modules have different importance. DLLs and APIs are both considered program calling resources. Based on the calling relationships between DLLs and APIs, program calling resources can be pictured as a tree named program behavior resource tree. Important block structures are selected from the tree as program behavior features. Finally, a virus detection model based on behavior the resource tree is proposed and verified by experiment which provides a helpful reference to virus detection.