• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.4
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• pp.336-344
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• 2007

A method is developed to evaluate partial safety factors for armor units, by which uncertainties of random variables in reliability function as well as wave height distribution with service periods could take into account straightforwardly. It is found that partial safety factors for resistance and wave height are correctly increased with improving target levels on failure of coastal structures at the same return and service periods. Therefore, it nay be possible to determine design variables through the same processes as those of deterministic method by using the partial safety factors for resistance and wave height evaluated in this paper, since uncertainties of random variables and the effects of service periods and target probability failure are directly considered in the processes of evaluation of partial safety factors.

• Tunnel and Underground Space
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• v.16 no.3 s.62
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• pp.203-208
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• 2006

This report is to introduce an article to compare 3 kinds of methods as RMR, Q-system and RMi published in Tunnel and Tunnelling Technology 2003. As rock mass classification is applied to estimate the amount of the support as an empirical design method, an attempt has been made to evaluate the parameters for classifications and their variations by Professor Nilsen and his team in Norway. Representability and reproducibility in measuring the field parameters are discussed and sensitivity of rating values in the three methods is also analyzed in this research. Although some parameters have high variation in rating among the 5 observers, the rock mass class has been found to be quite similar.

• The Transactions of the Korea Information Processing Society
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• v.7 no.9
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• pp.2797-2806
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• 2000

Recently, DDSs(Distributed Database Systems) have been implemented on V AN(V alue Added Network) as we know the amazing expansion of information network. DDS can yield significant cost and response time advantages over centralized systems for geographically distributed organizations. However, inappropriate design can result in high cost and poor response time to maintain the database at each site. In a DDS design, the main problem is how to select proper computer and how to allocate data fragment into a proper site. In this paper, we address DDS design problem of selecting the proper class of computers and the allocating data files on VAN. Also, the formulated model includes two objectives, the waited response time and the investment cost to include their relationship. Specially, the formulation of waited response time is based on M/M/1 queueing system to evaluate more precisely. GA(Genetic Algorithm), a kind of heuristic search method, is developed to search an optimal solution in the proposed design model and we show the simulation result to examine the algorithm performance.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.3
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• pp.142-151
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• 2004

A method for the determination of concrete armor unit weights with hydraulic stability and structural stability may be formulated in this paper. The hydraulic stability is analyzed by using Hudson's formula, the structural stability is also studied by evaluation of maximum flexural tensile stresses in armor unit induced by the impact loads and by comparison of those with the tensile resistance strength directly. The applicable criteria for concrete armor units can be represented as a function of design wave heights with return period, armor weights, and tensile strengths for the practical uses. In addition, reliability analyses for two failure modes are carried out to take into account some uncertainties. Finally, a series system for two-failure mode analysis can be made up straightforwardly, by which the optimal weights of armor units can be estimated with the various relative breakages, given the specific target probability of failure under the concepts of reliability-based design method.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.2
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• pp.29-37
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• 1998

Linear equations of motion for submersibles are one of the rest important design parameters, which are used as a governing equation for the shape design and the controller design. But, the estimated maneuvering coefficients in equations of motion by using empirical formulae, theoretical calculations or model tests might have some errors. Therefore the maneuvering coefficients should be verified from sea trial test. In this study, parallel extended Kalman filter method, Nelder & Mead Simplex method and genetic algorithm were applied to the parameter identification of roll maneuvering coefficients based on sea trial data. As a result, it was verified that Nelder & Mead Simplex method gave the most satisfactory results for the mathmatical models and the sea trial data used in this study.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.281-293
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• 2002

Empiricism has characterized the traditional methods of pile design; in essence, pile design recommendations are based on the accumulated knowledge of pile behaviour based on the construction and subsequent load testing of piles in soil and rock. In this paper, the traditional approaches to design of piles in rock will be briefly reviewed. It will be shown that the unrelated empirical relationships developed fur rock lead to considerable uncertainty in the design of piles. A new method for predicting the shaft resistance of piles socketed into rock, and based on fundamental principles is outlined. It is shown that the shaft resistance predictions of this method agree well with the field test data for rock and hard soil. It is demonstrated by way of a limited parametric study that shaft roughness and socket diameter are critical factors in the performance of piles constructed in these materials. The application of the method to piles socketed into the granites and gneisses of Korea is discussed by way of a case study and by reference to recent direct shear tests on these rocks.

• Computational Structural Engineering
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• v.3 no.1
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• pp.83-95
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• 1990

Many structural optimization problems are solved by numerical algorithms since these are complicated and nonlinear. To provide a wider base and popular it to structual design optimization, reliable, accurate and superlinearly convergent nonlinear programming algorithm with active-set strategy have been developed. One of these is RQP(recursive quadratic programming method). This algorithm has several parameters and its performance is influenced by variations of these key parameters. Therefore, an RQP algorithm is selected to enhance its numerical performances by choosing proper parameters. The paper persents these influences on its numerical performance. For comparison of performances, a structural design software for minimum weight of truss subjected to displacement, stress, and lower and upper bounds on design variables is also implemented.

• Journal of the Korean Geotechnical Society
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• v.18 no.1
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• pp.17-28
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• 2002

Tunnel construction is a complex three dimensional operation. Since, however, it is neither possible nor useful to simulate all conditions and parameters in detail, a simplified two dimensional model is commonly employed in practice. The simulation of three dimensional conditions by a two dimensional model should use empirical parameters. The numerical predictions indicate that analysis results are highly dependent on the parameters. An improved modelling method based on time was adopted to account for three dimensional effect at the tunnel heading and time dependent nature, and used to perform an analysis of tunnelling in decomposed granite. The effects of weathering degree, tunnel shape and multi-drift excavation were investigated by using the method. It is identified that a structural benefit can be obtained by adopting a horse-shoe-shaped cross section with multi-drift excavation in mixed-force ground condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.765-770
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• 2000

HDD로부터 방사되는 소음을 제어하려는 연구가 많이 진행되고 있다. 기존의 소음제어 방법은 주로 소음/진동 측정에 의한 실험적 방법과 엔지니어의 직감과 경험을 이용만 반복적 시행 착오법에 의존한다. 그러나, 이러한 방법은 제품 개발 기간의 단축이 요구되고 소음문제가 더욱 크게 대두되는 현실에 비추어 볼 때 부적절하다. 따라서, 본 연구에서는 해석적 방법을 통해 HDD 소음을 체계적으로 제어하고자 한다. 실험을 통해 HDD의 소음/진동특성을 파악하였고 문제가 되는 관심 주파수대역를 선정하였다. 복잡한 HDD 전체구조물에 대한 유한요소모델을 세우기 보다 소음/진동적 측면에서 문제가 되는 커버만 유한요소모델을 수립하고 부분구조합성법을 통해 전체 HDD의 동특성을 예측할 수 있는 모델을 수립하려 하며 현재 이러한 연구를 진행 중에 있다. 이러한 실험/해석모델이 완성되면 궁극적으로 SDM을 적용하여 소음/진동 특성이 향상된 HDD 구조물 설계기법을 제안할 수 있을 것으로 기대된다. 본 논문에서는 현재까지의 실험 및 해석결과와 향후 필요한 과제를 고찰하였다.

• Journal of Korea Game Society
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• v.16 no.4
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• pp.35-44
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• 2016

To apply the player's experiences to the design process of the game levels set by the developer, gameplay behavior analysis is needed. The player's behavior which is different by how much he got experiences from the play has generally been studied by one computational approach based on numerical data and the other HCI(human-computer interaction) approach through heuristic analysis. For the analysis of the player's behavior with the level design patterns in FPS(first-person shooter) games, in this paper those methods are used to code 12 main types of action, which in turn is simply categorized into 5 kinds of behavior pattern. Along with it, an optimized visualization is proposed to intuitively compare the flow of behavior pattern with the time of playing game.