• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.716-728
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• 1994

In this paper, fatigue tests were carried out to study the behavior of growth and coalescence of multi-surface cracks which were initiated at the semi-circular surface notches, and a simulation program was developed to predict their growth and coalescence behavior. By comparing the experimental result with those of the simulation based on SPC(surface point connection), ASME and BSI(British Standards Institution) conditions, we tried to enhance the reliance and integrity of structures. This shows that the simulation result has utility for fatigue life prediction.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1568-1570
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• 2005

The internet is already a part of life. It is very convenient and people can do almost everything with internet that should be done in real life. Along with the increase of the number of internet user, various network attacks through the internet have been increased as well. Also, Large-scale network attacks are a cause great concern for the computer security communication. These network attack becomes biggest threat could be down utility of network availability. Most of the techniques to detect and analyze abnormal traffic are statistic technique using mathematical modeling. It is difficult accurately to analyze abnormal traffic attack using mathematical modeling, but network simulation technique is possible to analyze and simulate under various network simulation environment with attack scenarios. This paper performs modeling and simulation under virtual network environment including $NGSS^{1}$ system to analyze abnormal traffic-flooding attack.

• Journal of Korea Multimedia Society
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• v.10 no.12
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• pp.1714-1725
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• 2007

This paper describes a top-down behavior planning framework in a simulation game from personality to real life action selection. The combined behavior creating system is formed by five levels of specification, which are personality definition, motivation extraction, emotion generation, decision making and action execution. Along with the data flowing process in our designed framework, NPC selects actions autonomously to adapt to the dynamic environment information resulting from active agents and human players. Furthermore, we illuminate applying Gaussian probabilistic distribution to realize character's behavior changeability like human performance. To elucidate the mechanism of the framework, we situated it in a restaurant simulation game.

• Structural Engineering and Mechanics
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• v.49 no.4
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• pp.509-521
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• 2014

In this paper two protocols of Wireless Sensor Networks (WSN) are examined through both a simulation and a case study. The simulation was performed with the optimized network (OPNET) simulator while comparing the performance of the Ad-Hoc on demand Distance Vector (AODV) and the Dynamic Source Routing (DSR) protocols. This is compared and shown with real-world measurement of deflection from eight wireless sensor nodes. The wireless sensor response results were compared with accelerometer sensors for validation purposes. It was found that although the computer simulation suggests the AODV protocol is more accurate, in the case study no distinct difference was found. However, it was shown that AODV is still more beneficial in the field as it has a longer battery life enabling longer surveying times. This is a significant finding as a large factor in determining the use of wireless network sensors as a method of assessing structural response has been their short battery life. Thus if protocols which enhance battery life, such as the AODV protocol, are employed it may be possible in the future to couple wireless networks with solar power extending their monitoring periods.

• Proceedings of the Safety Management and Science Conference
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• 2007.11a
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• pp.239-253
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• 2007

With the development of the Korean economy, the number of arson fire has been radically increased and become a huge problem and issue in Korea Society for last several decades. This study is to establish the fire life safety strategy regarding the arson fire through performing the computer simulation based on fire scenarios with researching domestic fire statistics and cutting edge techniques and methods for fire characteristics and fire dynamic. In addition, to design the fire life safety strategy depending on the arson fire pattern, the flow and characteristics of fire flames and smoke is analyzed by the computer modeling.

• Transactions of Materials Processing
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• v.9 no.4
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• pp.413-420
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• 2000

In the die casting process, the flow of liquid metal has significant influence on the quality of casting products and die life. For the optimal process design of front housing part of aircon compressor, various analyses were performed in this study by using computer simulation code, MAGMAsoft. The simulation has been focused on the molten metal behaviors during the filling and solidification stages for the sound casting products. Two cases of casting design that have different types of gating system are considered in the analysis. The potential sites where the casting defects may occur is examined by computer simulation and an improved design process is proposed. Also the effect of partial squeeze on the quality of casting products is considered and the optimal time lag after filling process is determined. For the die-stability, the effect of operational parameters such as die temperature, heat cycle and spot cooling on the die life has also been analyzed.

• Transactions of Materials Processing
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• v.19 no.7
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• pp.435-440
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• 2010

The creep life of 9Cr1MoVNb steel, in terms of Larson-Miller parameter(LMP), was evaluated by small punch(SP) creep simulation and verified by uniaxial creep test. By employing the elastoplastic FEM(finite element method), the small punch creep behaviors associated with various friction coefficients were simulated to identify a real friction phenomena. The friction coefficient, ${\mu}$=0.7, determined by comparing deflection history was used in the small punch creep simulation to find the equivalent stresses with which the relationship between punch load and uniaxial creep stress was found. The creep life was then predicted by the LMP, which was the relationship among the rupture time, temperature, and stress. Finally, the LMP calculated by SP-creep simulation was compared with that had computed by the uniaxial creep test and fairly matched LMPs were found.

• Journal of the Korean Society of Safety
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• v.21 no.1 s.73
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• pp.28-34
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• 2006

A procedure of estimating failure probability is demonstrated for a pressurized pipe of CrMo steel used at $538^{\circ}C$. Probabilistic fracture mechanics were employed considering variations of pressure loading, material properties and geometry. Probability density functions of major material variables were determined by statistical analyses of implemented data obtained by previous experiments. Distributions of the major variables were reflected in Monte Carlo simulation and failure probability as a function of operating time was determined. The creep crack growth life assessed by conventional deterministic approach was shown to be conservative compared with those obtained by probabilistic one. Sensitivity analysis for each input variable was also conducted to understand the most influencing variables to the residual life analysis. Internal pressure, creep crack growth coefficient and creep coefficient were more sensitive to failure probability than other variables.

• Journal of the Korea Safety Management & Science
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• v.10 no.1
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• pp.1-10
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• 2008

With the development of the Korean economy, the number of arson fire has been radically increased and become a huge problem and issue in Korea Society for last several decades. This study is to establish the fire life safety strategy regarding the arson fire through researching domestic fire statistics and performing the computer simulation based on fire scenarios with cutting edge techniques and methods for fire characteristics and fire dynamic. In addition, to design the fire life safety strategy depending on the arson fire pattern, the flow and characteristics of fire flames and smoke are analyzed by the computer modeling.

• Design & Manufacturing
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• v.13 no.2
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• pp.49-53
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• 2019

The temperature distribution and lifetime of molds were predicted by computer simulation analysis with various spraying and blowing process of high pressure die casting. After varying the spraying angle and time, the mold temperature, heat exchange and mold life were predicted. As the spraying angle increases, the maximum temperature of the mold decreases, which is because the spraying area increases and the heat exchange with the mold increases. Heat exchange occurs more actively in the blowing process than in the spraying process. This is because the cooling is not performed due to the steam generation. When the spraying angle is 50 degree, the minimum life of the mold is analyzed 200 times. After adjusting the blowing time from 5s to 3s, the minimum lifetime of the mold has been increased almost twice.