• KIPS Transactions on Computer and Communication Systems
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• v.8 no.2
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• pp.35-40
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• 2019

Traditional Malware Detection is susceptible for detecting malware which is modified by polymorphism or obfuscation technology. By learning patterns that are embedded in malware code, machine learning algorithms can detect similar behaviors and replace the current detection methods. Data must collected continuously in order to learn malicious code patterns that change over time. However, the process of storing and processing a large amount of malware files is accompanied by high space and time complexity. In this paper, an HDFS-based distributed processing system is designed to reduce space complexity and accelerate feature extraction time. Using a distributed processing system, we extract two API features based on filtering basis, 2-gram feature and APICFG feature and the generalization performance of ensemble learning models is compared. In experiments, the time complexity of the feature extraction was improved about 3.75 times faster than the processing time of a single computer, and the space complexity was about 5 times more efficient. The 2-gram feature was the best when comparing the classification performance by feature, but the learning time was long due to high dimensionality.

• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.76-81
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• 2003

전산유체공학에서 그래픽 인터페이스를 이용한 후처리 기법은 수렴된 해의 물리적 구조 및 특성을 이해하는데 있어 매우 중요하다. 따라서 본 연구에서는 그래픽 환경을 이용하여 압축성 유동 해석 코드인 CSCM 수치해석 코드의 후처리 과정을 개발함으로서 코드전체의 완전성을 높이고자 하였다. Visual C++프로그램을 이용하여 Mesh plot, XY plot, 벡터 plot 및 contour plot이 가능한 후처리 프로그램을 개발하였으며 실시간으로 수치해석의 수렴정도를 파악할 수 있는 잔류항에 대한 그래픽 기능을 제공하게 하였다. 개발된 후처리 과정을 2차원 Compression ramp 및 Bump 문제의 해석결과에 대해 본 연구결과와 현재 유체해석의 후처리 프로그램으로 많은 사용자를 확보하고 있는 AMTEC사의 Tecplot 8.0 버전의 결과를 서로 비교해 본 결과 좋은 일치성을 보여주었다.

• Journal of Energy Engineering
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• v.9 no.4
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• pp.309-318
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• 2000

핀-관 열교환기의 효율을 증대시키기 위하여는 열저항을 결정하는 데 있어서 중요한 역할을 하는 공기측 열전달 특성의 향상이 필요하다. 본 연구에서는 핀-관 열교환기의 공리측 성능을 해석하기 위해서 3차원 비압축성 Navier-Stokes 코드를 개발하였으며 이 코드는 시간항에 스칼라 내재적 근사분해법(scalar implicit approximate factorization)절차, 공간항에 유한체적법과 2차의 풍상차분법(upwind differencing)을 사용한다. 서로 다른 3개의 핀형상(평판핀, 슬릿핀, 파형핀)을 고려하였고 이들의 유동 및 열전달 특성을 연구하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 1998.10a
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• pp.155-160
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• 1998

VRML 파서는 VRML(.wrl) 파일을 읽기 위하여 반드시 필요한 부분으로서, 이미 공개되어 있는 것으로는 C/C++ 코드의 QvLib1.0과 Yacc & Lex로 개발한 VRML2.0 파서가 있다. 그러나 QvLib1.0의 경우 VRML2.0 파일에 적용할 수 없으며, Yacc & Lex로 개발한 파서는 생성된 소스 코드를 수정하기 어려울 뿐만 아니라 이를 수정하기 위해서는 자동 생성기인 Yacc & Lex의 사용 방법을 잘 알고 있어야 한다. 이에 본 논문에서는 C/C++ 코드의 VRML2.0 파서를 설계 및 구현하고 파싱의 결과로 생성된 parse tree를 이용하여 VRML 파일을 scene graph로 bygus할 수 있도록 하는 Scene Graph 생성기의 구현과정을 소개하였다. 또한 본 연구의 파서와 Scene Graph 생성기를 기 개발된 VRML 저작도구에 적용 및 테스트하였다.

• Composites Research
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• v.16 no.3
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• pp.9-17
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• 2003

In order to simulate the crack connection between cords and the interply crack growth in the belt-layer of real tire, 2 ply rubber/cord laminate specimens with exposed edges were tested in 4~11mm displacement control. Measurement of the crack connection is evaluated when crack reaches the half of the length between 45$^{\circ}$ aligned cords, and the amount of the crack growth is measured by the steel probe method. 2 dimensional analytic modeling was performed to simulate the crack connection between cords at the exposed edges. Also, the theoretical life of the specimens was calculated from the crack connection life between cords(critical value) and from the critical value to the final failure by the use of Tearing energy(T); the strain energy release per unit area of one fracture surface of a crack. Then, theoretical life was compared with those of experiments. The life prediction up to the critical value has about 20% error compared to experimental life, and up to the final failure about 65% error. Therefore, total theoretical life has about 45% error compared to the experimental life, which is conceivable in the case of rubber.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.06a
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• pp.351-355
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• 2001

2차원 바코드는 2차원인 점자식 코드로서 낮은 공간점유, 높은 정보, 다양한 정보처리 기능이 가능한 차세대 라벨링 기법이다. 즉, 2차원(2D) 심볼로지는 양축(X 방향, Y 방향)으로 데이터를 배열시켜 평면화 시킨것으로서 기존의 일차원(1D) 바코드 심볼로지가 가지는 문제점인 데이터 표현의 제한성, 즉 선적용 패키지와 같은 로트 번호, 구매 주문 번호, 수취자, 수랑 기타 정보 등의 다양한 내용을 바코드로 표현하여 대상물에 부착하거나 동반시킴으로써 1750년대 중반에 등장하게 되었고, 현재 많은 부분에서 사용하고 있다. 본 논문에서는 현재 많이 쓰이는 2 차원 바코드 중 하나인 Data Matrix 의 구성과 디코딩 알고리즘을 제안한다. Data Matrix는 데이터를 효율적으로 나타내기 위하며 각 정보의 교환에 따라 다른 인코딩 방식을 사용하고 있다. 디코딩 알고리즘은 그에 따라서 구현되었다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.83-89
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• 2012

Recently, due to widespread use of smartphones, the number of applications of the QR code is increased rapidly. QR codes, a kind of 2-dimensional barcode, is used to encode information such as simple URLs or namecards, especially for corporates' advertisement. Users can get some information easily by taking picture of the target QR code, however, fake or altered QR codes can cause serious problems, e.g., URL hijacking or infringement of private information because no one can identify the buried information in the QR code by his naked eye. In this paper, I summarize threats to the QR code and present how to tackle these threats.

• Tunnel and Underground Space
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• v.33 no.1
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• pp.57-69
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• 2023

In this study, we simulated induced seismicity in the Groningen natural gas reservoir using 2D hydro-mechanical coupled discrete element modelling (DEM). The code used is PFC2D (Particle Flow Code 2D), a commercial software developed by Itasca, and in order to apply to this study we further developed 1)initialization of inhomogeneous reservoir pressure distribution, 2)a non-linear pressure-time history boundary condition, 3)local stress field monitoring logic. We generated a 2D reservoir model with a size of 40 × 50 km² and a complex fault system, and simulated years of pressure depletion with a time range between 1960 and 2020. We simulated fault system failure induced by pressure depletion and reproduced the spatiotemporal distribution of induced seismicity and assessed its failure mechanism. Also, we estimated the ground subsidence distribution and confirmed its similarity to the field measurements in the Groningen region. Through this study, we confirm the feasibility of the presented 2D hydro-mechanical coupled DEM in simulating the deformation of a complex fault system by hydro-mechanical coupled processes.

• The Journal of the Korea Contents Association
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• v.18 no.10
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• pp.431-442
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• 2018

2-dimensional barcode, QR code has been used for containing various information such as image, video, map, and business cards. Currently, a smartphone is used as a QR code scanner, displaying the code and converting it to a standard URL for a website. However, QR codes are not very common in encrypted application and so have a few applications. This paper proposes a new color-code, which integrates the conventional QR code and color design, and can be effectively used in some product certification system. The proposed method exploits the fact that genuine code is produced by CMYK color model, but the counterfeit is captured by RGB color model and during this process, color information of the code is changed. This paper introduces the color matrix model to measure the distortion between genuine code and counterfeit code. By investigating the statistical characteristics of color matrix, an effective detection of print image forgeries are designed. Various experiments with color codes show that the proposed system can be effectively used in product certification systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.583-588
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• 2010

The nonlinearity and high deformability of rubber make accurate analysis of the behavior of cord-rubber composites a challenging task. Some researchers have adopted the third phase between cord and rubber and have carried out three-phase modeling. However, it is difficult to determine the thickness and properties of the interface in cord-rubber composites. In this study, a two-dimensional finite-element method (2D FEM) is used to investigate the effective and normalized moduli of cord-rubber composites having interfaces of various thicknesses; this model takes into account the 2D generalized plane strain and a plane strain element. The neo-Hookean model is used for the properties of rubber, several interface properties are assumed and three loading directions are selected. It is found that the properties and thickness of the interface can affect the nonlinearity and the effective modulus of cord-rubber composites.