• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.31-34
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• 2010

본 논문에서는 교량의 자유진동 모드의 중첩원리를 이용하여 KTX-교량의 동적상호작용 해석법을 제시한다. 이를 위하여 모드중첩법에 기초한 3차원 교량-차량의 에너지 식으로부터 에너지원리를 적용하여 교량과 차량의 상호작용을 고려할 수 있는 운동방정식을 유도한다. 이때 운동방정식의 해는 Newmark-${\beta}$ 방법을 사용한다. 그리고 궤도의 불규칙성은 FRA의 6등급 분류규정을 고려하여 각 등급별로 고속철도의 열차속도에 따르는 응답을 분석한다. 실제 고속철도에 사용되는 PSC 박스형 교량을 상용프로그램(MIDAS)를 이용하여 모델링하고 그로부터 각 모드별 형상을 얻어내어 본 논문에서 개발한 열차-교량 상호작용 프로그램에 입력하여 상호작용 해석을 수행한다.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.455-460
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• 2001

For some applications, the computational structure changes dynamically during the program execution. When this happens, static partitioning and allocation of tasks are not enough to achieve high performance in parallel computers. In this paper, we propose a dynamic load balancing algorithm efficiently distributes the computation with dynamically growing tree structure to processors. We present an implementation technique for the algorithm on mesh architectures, and analyze its complexity. We also demonstrate through experiments how our algorithm provides good quality solutions.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.3
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• pp.121-128
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• 2021

Piloti-type buildings in Korea are usually composed of lower frames and upper shear wall structures. Piloti-type buildings have been seriously damaged during earthquakes because of the construction of soft and weak stories. Piloti-type buildings with edge cores are two-way unsymmetric planes. This paper analyzed and obtained the dynamic response for structures modeled using a multistory two-way asymmetric system. The numerical results, obtained using the Newmark-β method, show the time-history responses and trends of maximum displacements and shear forces. The purpose of this study is to evaluate the effect of reinforcement on dynamic response when a shear wall or brace is reinforced in the corner opposite the piloti.

• Tunnel and Underground Space
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• v.16 no.1 s.60
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• pp.58-72
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• 2006

In recent years, not only the occurrences but the magnitude of earthquakes in Korea are on an increasing trend and other sources of dynamic events including large-scale construction, operation of hi띤-speed railway and explosives blasting have been increasing. Besides, the probability of exposure fir rock joints to free faces gets higher as the scale of rock mass structures becomes larger. For that reason, the frictional behavior of rock joints under dynamic conditions needs to be investigated. In this study, a shaking table test system was set up and a series of dynamic test was carried out to examine the dynamic frictional behavior of rock joints. In addition, a computer program was developed, which calculated the acceleration and deformation of the sliding block theoretically based on Newmark sliding block procedure. The static friction angle was back-calculated by measuring yield acceleration at the onset of slide. The dynamic friction angle was estimated by closely approximating the experimental results to the program-simulated responses. As a result of dynamic testing, the static friction angle at the onset of slide as well as the dynamic friction angle during sliding were estimated to be significantly lower than tilt angle. The difference between the tilt angle and the static friction angle was $4.5\~8.2^{\circ}$ and the difference between the tilt angle and the dynamic friction angle was $2.0\~7.5^{\circ}$. The decreasing trend was influenced by the magnitude of the base acceleration and inclination angle. A DEM program was used to simulate the shaking table test and the result well simulated the experimental behavior. Friction angles obtained by shaking table test were significantly lower than basic friction angle by direct shear test.

• The Korean Journal of Applied Statistics
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• v.31 no.4
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• pp.497-505
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• 2018

Attacking computer systems using ransomware is very common all over the world. Since antivirus and detection methods are constantly improved in order to detect and mitigate ransomware, the ransomware itself becomes equally better to avoid detection. Several new methods are implemented and tested in order to optimize the protection against ransomware. In our work, 582 of ransomware and 942 of normalware sample data along with 30,967 dynamic action sequence variables are used to detect ransomware efficiently. Several variable selection techniques combined with various machine learning based classification techniques are tried to protect systems from ransomwares. Among various combinations, chi-square variable selection and random forest gives the best detection rates and accuracy.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.130-133
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• 2019

수중(submerged)에 부유(floating)식으로 계류되는 거주목적의 구조체 설계(design basis) 관련 연구로서 계류안정성 모델(수중가옥)을 만들고 거동을 정수압적 유체역학적으로 수치분석한다. 임의 가정한 수중가옥의 1)배수량 규모 2) 함체형상에 따른 환경압 하에서의 계류안정성을 a)부력중심, b)무게중심과 가변하중의 변위에 따른 c)함체 기울기를 MATLAB프로그램을 이용하여 산정한다. 나아가 수중가옥의 동적(hydrodynamic) 계류안정성을 임의 시공 장소인 독도의 기상청 울릉도-독도 부이 최근 관측치를 근거로 OrcaFlex프로그램을 이용하여 분석하므로써 수중가옥의 수중건축 시공간상 계류안정성 설계요건(design basis)을 구체화 한다.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.29-36
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• 2012

In this study, frequently passing vehicles with two, three, four, and five axles were chosen through traffic volume analysis in Kyung-In Expressway in order to analyze how the road roughness and vehicle speed affect on the dynamic loads for roads in various vehicle classes. Dynamic loads according to chosen vehicles are estimated by TruckSim program. Dynamic load amplification factor is ratio between dynamic and static loads, and it is also determined for each vehicle classes. From the result of dynamic loads estimated by the dynamic load amplification factor, it is shown that for three-axles vehicle, when IRI is 3.5 and vehicle speed is 100km/hr, asphalt pavements receive additional 36% of static loads in maximum. The analysis of the amplification factor according to each vehicle classes also indicates that the amplification factor increases as the distance between the axles becomes smaller and each axle receives more loads.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.167-174
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• 2009

The simulation of dynamic load was conducted based on surface profile on asphalt concrete pavement, vehicle speeds, and suspension types using a truck simulation program. The results of the simulated dynamic load based on different surface profile, vehicle speeds, and suspension types are analyzed. As pavement roughness and vehicle speed are increased, the dynamic load was increased. Walking beam suspension produces greater dynamic load than air spring suspension. Pavement damage index is calculated based on covariance of dynamic load and Paris-Erdogan fracture parameter, n which is based on creep compliance tests of asphalt mixtures used in Korea. The higher covariance of dynamic load, confidence level, and fracture parameter are used, the greater pavement damage index is obtained. Specification of pavement roughness can be developed in various vehicle speeds and asphalt mixtures, and pay factor can be determined after constructing asphalt concrete pavement using pavement damage concepts.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.460-462
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• 2001

테스트 데이터의 자동 생성은 소프트웨어 테스팅에서 가장 중요하면서도 어려운 부분이다. 대부분의 데스트 데이터 자동생성에 관한 연구는 명세로부터 테스트 데이터를 자동 생성하는 방식이며 이틀 위해 정확한 정형적 명세를 필요로 한다. 본 논문에서 는 프로그램을 실 행하지 않고 프로그램의 동적인 특성을 분석할 수 있는 요약 해석(abstract interpretation) 방법과 선후 지배 관계(pre-, postdominance relationship)를 이용하여 프로그램 코드로부터 직접 테스트 데이터를 자동 생성할 수 있는 방법 을 제안한다.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.5
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• pp.13-23
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• 2001

In the companion paper, F. E. formulation for the geometric and plastic non-linear analysis of steel jacket structures subjected to wave and earthquake loadings was presented and the main processor was developed. In this paper, the pre/post processor are developed in order to analyze the output results effectively as well as to prepare the input data efficiently. Furthermore, the numerical examples are presented and discussed for linear and non-linear analysis of steel jackets under environmental loadings.