• Journal of the Korean GEO-environmental Society
• /
• v.5 no.1
• /
• pp.13-25
• /
• 2004

Granular compaction piles increase the load bearing capacity of the soft ground and reduce the settlement of foundation built on the reinforced soil. The granular compaction group piles also accelerate the consolidation of the soft ground and prevent the liquefaction caused by earthquake using the granular materials such as sand, gravel, stone etc. However, this method is one of unuseful method in Korea. In the present study, the optimum locations of granular compaction group piles using genetic algorithm are proposed. The results were shown that the bearing capacity was increased in the case concentrated on the central part of the group piles. Also, the optimum design for total weight of granular compaction group piles was carried out in consideration of the economical efficiency and parametric studies were performed to examine the effects of parameters at the design of granular compaction group piles.

• Composites Research
• /
• v.33 no.6
• /
• pp.353-359
• /
• 2020

In this work, a contour-based section analysis method incorporating the use of Bézier curves is attempted for the construction of optimal structural design framework of composite helicopter blades. The suggested section analysis method is able to analyze composite blades with solid cores made of arbitrary materials and geometric shapes. The contour-based section analysis method is integrated into a blade structural optimization framework to confirm the efficiency of the present approach. The numerical simulation result demonstrates that the optimized blade configurations are obtained with a reduction in mass by 52%, compared to the baseline blade. For the structural optimization of composite blades with 19 subsections, it takes about one hour for the successful optimization while satisfying all the design constraints considered in this study, which reveals the efficiency of the present approach.

• Journal of the Korean GEO-environmental Society
• /
• v.1 no.1
• /
• pp.51-56
• /
• 2000

Granular piled raft systems have been effectively used in soft ground foundation not only to reduce settlements but also to improve bearing capacity. In the present study, the finite element method of analysis on a basis of the plate theory is proposed to predict non-uniform settlements at the interface between the raft and foundation soils. To verify the validity of the proposed method of analysis and the predicted settlements of granular piled raft systems, comparisons are made with the results presented in the previous research(Kim et al., 1999). Finally, behavior characteristics with various patterns of the granular piled raft systems and effects of the settlement reduction are analyzed in connection with the design parameters.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.30 no.1
• /
• pp.118-126
• /
• 2024

In this paper, the research contents and results related to the automation of the hull-form optimal design of container ships are summarized. A container ship is a ship that generally operates near Froude number of 0.26. To implement hull-form optimal design automation for ships operating at this speed, an optimization algorithm, a hull-form change algorithm, a ship performance prediction algorithm, an automation algorithm, and an iterative calculation technique were applied to develop a numerical analysis computer program that enables hull-form optimal design automation of the container ship, and it was named HOTCONTAINER. In this study, a sensitivity analysis algorithm was developed and applied to appropriately set design variables for hull-form optimal design. To understand the reliability and real ship applicability of the developed algorithm, a numerical analysis was performed on KCS(KRISO Container Ship), a container ship that has been studied in various ways worldwide. Consequently, the optimal ship was derived, and the wave resistance, wave pattern, and wave height of the target and optimal ship were compared. In conclusion, compared the target ship, the optimal ship a 47.63% decrease in wave resistance, and the displacement and wet surface area decreased by 0.50% and 0.39%, respectively.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.31 no.5
• /
• pp.243-250
• /
• 2018

In this paper, design technique using genetic algorithms(GA) for design optimization of composite leaf springs is presented here. After the initial design has been validated by the car plate spring as a finite element model, the genetic algorithm suggests the process of optimizing the number of layers of composite materials and their angles. Through optimization process, the weight reduction process of leaf springs and the number of repetitions are compared to the existing algorithm results. The safety margin is calculated by organizing a finite element model to verify the integrity of the structure by applying an additive sequence optimized through the genetic algorithm to the structure. When GA is applied, layer thickness and layer angle of complex leaf springs have been obtained, which contributes to the achievement of minimum weight with appropriate strength and stiffness. A reduction of 65.6% original weight is reached when a leaf steel spring is replaced with a leaf composite spring under identical requirement of design parameters and optimization.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.15 no.6
• /
• pp.1011-1016
• /
• 2020

Rapid change in network topology in high-speed VANET(: Vehicular Ad Hoc Network) is an important task for routing protocol design. Selecting the next hop relay node that affects the performance of the routing protocol is a difficult process. The disadvantages of AODV(: Ad Hoc On-Demand Distance Vector) related to VANET are end-to-end delay and packet loss. This paper proposes the AAODV (Advanced AODV) technique to reduce the number of RREQ (: Route Request) and RREP (: Route Reply) messages by modifying the AODV routing protocol and adding direction parameters and 2-step filtering. It can be seen that the proposed AAODV reduces packet loss and minimizes the effect of direction parameters, thereby increasing packet delivery rate and reducing end-to-end delay.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.11a
• /
• pp.257-265
• /
• 2009

The present study deals with the leading edge shape on a wing-body junction to decrease a horseshoe vortex, one of the main factors to generate the secondary flow losses. The shape of leading-edge is optimized with design variables form the leading-edge shape. Approximate optimization design method is used for the optimization. The study is investigated using $FLUENT^{TM}$ and $iSIGHT^{TM}$. As the result, total pressure coefficient of the optimized design case was decreased about 9.79% compare to the baseline case.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2004.04a
• /
• pp.17-21
• /
• 2004

본 논문에서는 실시간으로 상수 및 변수의 병렬 매칭이 가능한 새로운 구조의 하드웨어 기반 룰-베이스시스템 구조를 제안한다. 이 시스템은 context-aware computing 시스템에서 상황 인식을 위한 기법으로 적용될 수 있다. 제안된 구조는 기존의 하드웨어 기반의 구조가 가지는 룰의 표현 및 룰의 구성에서 발생하는 제약을 상당히 감소시킬 수 있다. 이를 위해 변형된 형태의 content addressable memory(CAM)와 crossbar switch network(CSN)가 사용되었다. 변형된 형태의 CAM으로 구성된 지식-베이스는 동적으로 데이터의 추가 및 삭제가 가능하다. 또한 CSN은 input buffer와 working memory(WM) 사이에 위치하여, 시스템 외부 및 내부에서 동적으로 생성되거나, 시스템 설정에 의해 지정된 데이터들의 조합 및 pre-processing module(PPM)을 이용한 연산을 통하여 WM을 구성하는 데이터를 생성시킨다. 이 하드웨어 룰-베이스 시스템은 SystemC 2.0을 이용하여 설계하였으며 시뮬레이션을 통하여 그 동작을 검증하였다.

• Journal of Wetlands Research
• /
• v.20 no.2
• /
• pp.105-115
• /
• 2018

The frequency analysis of hydrometeorological data is one of the most important factors in response to natural disaster damage, and design standards for a disaster prevention facilities. In case of frequency analysis of hydrometeorological data, it assumes that observation data have statistical stationarity, and a parametric method considering the parameter of probability distribution is applied. For a parametric method, it is necessary to sufficiently collect reliable data; however, snowfall observations are needed to compensate for insufficient data in Korea, because of reducing the number of days for snowfall observations and mean maximum daily snowfall depth due to climate change. In this study, we conducted the frequency analysis for snowfall using the Bootstrap method and SIR algorithm which are the resampling methods that can overcome the problems of insufficient data. For the 58 meteorological stations distributed evenly in Korea, the probability of snowfall depth was estimated by non-parametric frequency analysis using the maximum daily snowfall depth data. The results of frequency based snowfall depth show that most stations representing the rate of change were found to be consistent in both parametric and non-parametric frequency analysis. According to the results, observed data and Bootstrap method showed a difference of -19.2% to 3.9%, and the Bootstrap method and SIR(Sampling Importance Resampling) algorithm showed a difference of -7.7 to 137.8%. This study shows that the resampling methods can do the frequency analysis of the snowfall depth that has insufficient observed samples, which can be applied to interpretation of other natural disasters such as summer typhoons with seasonal characteristics.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.2
• /
• pp.89-97
• /
• 2020

In this study, a numerical analysis was performed on 26 inch single and coaxial propeller using the ANSYS Fluent 19.0 Solver to analyse the effect of the distance between coaxial propellers as one of the design parameter. The Moving Reference Frame (MRF) method was used for single propeller, while the sliding mesh method was used for a coaxial propeller to analyse the flow field varying with azimuth angle. The thrust and power are decreased as the upper and lower propeller approaching each other. As H/D is increased, interference between the propellers is decreased. According to the flow field variable contour of the coaxial propeller, it appears that the change in aerodynamic performance is due to the loading effect and the tip vortex wake effect.