• Journal of the Korea Society for Simulation
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• v.12 no.2
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• pp.63-73
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• 2003

The major objective of this paper is to propose the method of attacker and host modeling for cyber-attack simulation. In the security modeling and simulation for information assurance, it is essential the modeling of attacker that is able to generate various cyber-attack scenarios as well as the modeling of host, which is able to represent behavior on attack concretely The security modeling and simulation, which was announced by Cohen, Nong Ye and etc., is too simple to concretely analyze attack behavior on the host. And, the attacker modeling, which was announced by CERT, Laura and etc., is impossible to represent complex attack excepting fixed forms. To deal with this problem, we have accomplished attacker modeling by adopted the rule-based SES which integrates the existing SES with rule-based expert system for synthesis and performed host modeling by using the DEVS formalism. Our approach is to show the difference from others in that (ⅰ) it is able to represent complex and repetitive attack, (ⅱ) it automatically generates the cyber-attack scenario suitable on the target system, (ⅲ) it is able to analyze host's behavior of cyber attack concretely. Simulation tests performed on the sample network verify the soundness of proposed method.

• Korean Journal of Computational Design and Engineering
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• v.19 no.4
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• pp.316-323
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• 2014

This paper proposes the 3D modeling and simulation technique for predicting the integrated performance of combat vehicle. To consider the practical driving and firing condition of a combat vehicle, the full vehicle model, which can define the six degrees-of-freedom of vehicle motion and various firing angles, is developed. The critical design parameters such as the stiffness and damping coefficient of suspension system are applied to construct the analysis model of vehicle. A simple ballistic model, which incorporates the empirical interior ballistic model and the point mass trajectory model, is built to estimate the firing range and the firing recoil force. To predict the integrated performance and analyze the effect of system parameters, MATLAB/SIM-ULINK model of a combat vehicle for performing the real time simulation is also developed. Several simulation tests incorporating the road bump and the firing recoil force are presented to confirm the effectiveness of the proposed vehicle model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.2
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• pp.105-116
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• 2018

In this study, we consider the assembly line balancing (ALB) problem which is known as an very important decision dealing with the optimal design of assembly lines. We consider ALB problems with soft constraints which are expected to be fulfilled, however they are not necessarily to be satisfied always and they are difficult to be presented in exact quantitative forms. In previous studies, most researches have dealt with hard constraints which should be satisfied at all time in ALB problems. In this study, we modify the mixed integer programming model of the problem introduced in the existing study where the problem was first considered. Based on the modified model, we propose a new algorithm using the genetic algorithm (GA). In the algorithm, new features like, a mixed initial population selection method composed of the random selection method and the elite solutions of the simple ALB problem, a fitness evaluation method based on achievement ratio are applied. In addition, we select the genetic operators and parameters which are appropriate for the soft assignment constraints through the preliminary tests. From the results of the computational experiments, it is shown that the proposed algorithm generated the solutions with the high achievement ratio of the soft constraints.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.4
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• pp.72-82
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• 1990

A simple numerical analysis procedure has been proposed to trace the response of unstiffened offshore tubular members subjected to lateral impacts and eventually to estimate the consequential extent of damage. In the procedure a tubular member is reduced to a spring-mass system having two degrees-of-freedom. one for local denting deformation and the other for that of overall bending. Results of impact tests have been correlated with those of numerical analysis in order to achieve an empirical representation of the strain-rate sensitivity and other dynamic effects upon the spring coefficient for bending deformation. The theoretical estimates of extents of damage correlate reasonably well with those obtained in experiments.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.5-11
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• 2015

In a pressurized water reactor (PWR), control rod assembly (CRA) falls into the guide tubes of a fuel assembly due to gravity for scram. Various theoretical approaches and numerical analyses have been performed because its shape is simple and its design was completely developed several decades ago. A control rod assembly for a sodium-cooled faster reactor (SFR) which is geometrically more complicated is being actively developed in Korea nowadays. Drop time and impact velocity of a CRA are important parameters with respect to reactivity insertion time and the mechanical robustness of a CRA and a guide duct. In this paper, computational method considering simultaneously the equation of motion for rigid body and the Navier-Stokes equations for fluid is suggested and verified by comparison with theoretical analysis results. Through this valuable CFD analysis method, drop time and impact velocity of initially designed SFR CRA are evaluated before performing scram tests with it.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.271-276
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• 2004

In this paper. dynamic behavior of the cracked beam under a moving mass is presented using the finite element method (FEM). Model accuracy is improved with the following consideration: (1) FE model with Timoshenko beam element (2) Additional flexibility matrix due to crack presence (3) Interaction forces between the moving mass and supported beam. The Timoshenko bean model with a two-node finite element is constructed based on Guyan condensation that leads to the results of classical formulations. but in a simple and systematic manner. The cracked section is represented by local flexibility matrix connecting two unchanged beam segments and the crack as modeled a massless rotational spring. The inertia force due to the moving mass is also involved with gravity force equivalent to a moving load. The numerical tests for various mass levels. crack sizes. locations and boundary conditions were performed.

• Journal of Families and Better Life
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• v.19 no.6
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• pp.241-263
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• 2001

The objectives of this study were empirically to test the reformative model for Korean sacrificial rite and to investigate the effects of demographic variables. the survey was conducted by means of questionnaire with 600 persons located in Seoul. Major findings were as follows ; 1, Sacrificial day ; was displayed (1) dead day (2) holiday in back and forth of dead day 2. Sacrificial time ; was showed (1) 8-9 h. p.m (2) 6-7 h. p.m 3. Sacrificial extent ; was displayed (1) grandparents and parents (2) only parents 4. Participative extent ; was showed (1) Cousin (2) only sons and daughters 5. Sacrificial procedure ; was displayed twice deep bow and 1 minute\`s silent prayer. 6. New year's and Chusok's rite ; was showed (1) simple foods (2) joint leisure time 7. Sacrificial table ; was displayed (1) boiled rice . water . gustoish articles. (2) omission of food table 8. rite\`s socialization ; was showed (1) delivery and marketing sale\`s food (2) special sacrificial restaurant. 9. Womens'and mens'difference ; women were active 7ut men were passive 10. Age's difference ; excepting 30-40, the all generations were more reformative. 11. Number of brothers ; small number of brothers were more reformative than a many number. 12. Sacrificial manager or not , managers were conservative than persons were not managers.

• Computers and Concrete
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• v.13 no.6
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• pp.799-827
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• 2014

In this paper, a theoretical and experimental study of the sectional behaviour of reinforced concrete beams subjected to short-term loads is carried out. The pure bending behaviour is analysed with moment-curvature diagrams. Thus, the experimental results obtained from 24 beams tested by the authors and reported in literature are compared with theoretical results obtained from a layered model, which combines the material parameters defined in Model Code 2010 with some of the most recognized tensions-tiffening models. Although the tests were carried out for short-term loads, the analysis demonstrates that rheological effects can be important and must be accounted to understand the experimental results. Another important conclusion for the beams tested in this work is that the method proposed by EC-2 tends to underestimate the tension-stiffening effects, leading to inaccuracies in the estimations of deflections. Thus, the actual formulation is analysed and a simple modification is proposed. The idea is the separation of the deflection prediction in two parts: one for short-term loads and other for rheological effects (shrinkage). The results obtained are in fairly good agreement with the experimental results, showing the feasibility of the proposed modification.

• Structural Engineering and Mechanics
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• v.61 no.1
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• pp.161-169
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• 2017

This study aimed to develop a simple and effective method to facilitate the experimental research on mechanical properties of masonry under biaxial compressive stress. A series of tests on full-scale brick masonry panels under biaxial compression have been performed in limited principal stress ratios oriented at various angles to the bed joints. Failure modes of tested panels were observed and failure features were analyzed to reveal the mechanical behavior of masonry under biaxial compression. Based on the experimental data, the failure curve in terms of two orthotropic principal stresses has been presented and the failure criterion of brick masonry in the form of the tensor polynomial has been established, which indicate that the anisotropy for masonry is closely related to the difference of applied stress as well as the orientation of bed joints. Further, compared with previous failure curves and criteria for masonry, it can be found that the relative strength of mortar and block has a considerable effect on the degree of anisotropy for masonry. The test results demonstrate the validity of the proposed experimental method for the approximation of masonry failure under biaxial compressive stress and provide valuable information used to establish experimentally based methodologies for the improvement of masonry failure criteria.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.620-625
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• 2011

A simple, rapid potentiometric back titration of Isoniazid (INH) in the presence of Rifampicin (RIF) in tablets and syrups is described. The method is based on the oxidation of INH by a known excess of copper (II) ion and the back titration of unreacted copper (II) ion potentiometrically with ascorbic acid using a lab-made Copper Based Mercury Film Electrode (CBMFE). The titration conditions have been optimized for the determination of 1.0-10.0 mg of INH in pure and dosage forms. The precision and accuracy of the method have been assessed by the application of lack-of-fit test and other statistical methods. Interference was not caused by RIF and other excipients present in dosage forms. Application of the method for INH assay in tablets and syrups was validated by comparison of the results of proposed method with that of the British Pharmacopoeia (BP) method using F- and t- statistical tests of significance.