• Steel and Composite Structures
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• v.4 no.6
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• pp.453-469
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• 2004

In this article, a genetic algorithm based optimum design method is presented for non-linear steel frames with semi-rigid connections. The design algorithm obtains the minimum weight frame by selecting suitable sections from a standard set of steel sections such as European wide flange beams (i.e., HE sections). A genetic algorithm is employed as optimization method which utilizes reproduction, crossover and mutation operators. Displacement and stress constraints of Turkish Building Code for Steel Structures (TS 648, 1980) are imposed on the frame. The algorithm requires a large number of non-linear analyses of frames. The analyses cover both the non-linear behaviour of beam-to-column connection and $P-{\Delta}$ effects of beam-column members. The Frye and Morris polynomial model is used for modelling of semi-rigid connections. Two design examples with various type of connections are presented to demonstrate the application of the algorithm. The semi-rigid connection modelling results in more economical solutions than rigid connection modelling, but it increases frame drift.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.381-386
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• 1994

Recently, the design and construction of massive concrete structures are increased. But, the temperature rise within a large concrete mass make the construction of massive concrete structures be very difficult. Therefore, in Seohae Grand Bridge Project, the field measurement of hydration heat for the massive concrete footings(11$\times$22$\times$4m) was carried out. It was shown to be possible to construct the massive concrete footing successfully by application of pipe cooling system. And the measurement results showed that standard code for concrete practice was very conservative.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.10a
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• pp.216-223
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• 1993

The safety factors of current standard code are considered to be not appropriate compared to design and construction practices, even this safety factors are not determined from probabilistic study but merely from experiences and practices. This study pripose the optimum safety indices based on expected total cost minimization using only three parameters, which are the level of the failure cost to the initial cost by improvement in safety, and the order of the initial cost function.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.5
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• pp.509-520
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• 2020

Currently, the criteria for input motions used in dam seismic design are clearly presented in general provisions of seismic design (KDS 17 10 00), and seismic ground motion records should be matched to the standard design response spectrum. However, the effect on the results is not assessed according to the selection of the seismic ground motion records, making it difficult to select seismic input motions. Therefore, in this study, the change in the amount of crest settlement of an embankment dam was assessed through numerical analysis after matching the seismic ground motion records of domestic and overseas earthquakes in accordance with the standard design response spectrum provided in the seismic design code (KDS 17 10 00). The results showed that the behavior of the upper part of the embankment, such as maximum acceleration at the crest and amplification through the dam, rather than the effect of free-field acceleration, had a greater effect on the amount of crest settlement. Moreover, it was confirmed that even an input seismic motion matched to the standard design response spectrum can make a difference in settlement depending on the characteristics of amplification through a dam body.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1405-1408
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• 2006

C++ 언어는 객체지향 프로그래밍 언어로, 기존의 C++ 프로그램은 각각의 플랫폼에 따른 컴파일러를 통해 목적기계의 코드(object code)로 변환되므로 실행되는 플랫폼에 의존적인 단점이 있다. 이러한 단점을 보완하는 방법으로 스택기반의 가상기계와 가상기계의 입력형태인 중간코드를 이용하는 기법이 있다. EVM(Embedded Virtual Machine)은 ANSI C, ISO/IEC C++ 언어와 SUN사의 Java 언어 등을 모두 수용할 수 있는 임베디드 시스템 기반의 가상기계이며, EVM에서 실행되는 중간코드인 SIL(Standard Intermediate Language)은 객체지향 언어와 순차적인 언어를 모두 수용하기 위한 명령 코드의 집합으로 설계되어 있다. 본 논문에서는 C++ 컴파일러를 통해 생성된 SIL 코드가 올바른지 검증하고 원시코드의 분석을 용이하게 하기 위해서 SIL 코드를 어셈블리 코드와 유사한 형태의 재 표현된 C++ 프로그램으로 역컴파일하는 시스템을 설계하고 구현하였다.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.27-32
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• 1998

This paper presents the development of a two-dimensional model for investigating the fluid flow in water jet and calculating the velocity and pressure distributions. The mathematical formulation as a standard k-$\epsilon$ model was solved employing a general thermofluid-mechanics computer program, PHOENICS code, which is based on the Semi-Implicit Method Pressure Linked Equations(SIMPLE) algorithm. The developed code was applied to water jet design to determine the nozzle size, and investigated the effect of the change of nozzle location. Calculated results showed that the flow pattern is not changed as the change of nozzle location.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.2
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• pp.158-165
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• 1996

The knowledge of air flow in an engine room has become more and more important in recent car design. The fluid flow in the engine compartment was investigated by numerical analysis. Due to the complex geometry of the engine compartment, mesh generation is a time-consuming job. In this research, the "ICEM" code was used to generate meshes by the Cartesian mesh model. The Reynolds-averaged Navier Stokes equations, together with the porous flow model for radiator and condenser, were solved. Computation was performed for the steady, incompressible, and high speed viscous flow, adopting the standard K-ε turbulence model. The "STAR-CD" code was used as a solver. The effect of car front openning area on the flow in engine room was also investigated.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.193-199
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• 2002

According to the NOx level requirement of annex Vl to IMO(International Maritime Organization) MARPOL 73/78, this regulation shall apply to each diesel engine with a power output of more than 130 ㎾ which is installed on a ship constructed and undergoes a major conversion on or after 1 January 2000. It is inevitable to adopt IMO standard for marine engines. Therefore, most of diesel engines which are being currently built should be tested and surveyed in accordance with the NOx technical code. In this study, various technics of NOx reduction methods were investigated for the diesel engines and the methods of NOx measuring were introduced by the new and simplified field detecting equipment. These results can be utilized for the basic design and developement of diesel engine for NOx reduction.

• Journal of Ubiquitous Convergence Technology
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• v.2 no.1
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• pp.12-17
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• 2008

In this paper, the 128bit AES block cipher algorithm OCB (Offset Code Book) mode for privacy and authenticity of high speed packet data was efficiently designed in C language level and was optimized to support the required capacity of contents server using high performance DSP. It is known that OCB mode is about two times faster than CBC-MAC mode. As an experimental result, the encryption / decryption speed of the implemented block cipher was 308Mbps, 311 Mbps respectively at 1GHz clock speed, which is 50% faster than a general design with 3.5% more memory usage.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.9 s.351
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• pp.31-37
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• 2006

Low-density parity-check (LDPC) codes are recently emerged due to its excellent performance. The standard for European high definition satellite digital video broadcast, DVB-S2 has adopted LDPC codes as a channel coding scheme. This paper proposes a DVB-S2 LDPC decoder architecture using a hybrid parity check matrix which is efficient in hardware implementation for both decoders and encoders. The hybrid H-matrices are constructed so that both the semi-random technique and the partly parallel structure can be applied to design encoders and decoders. Using the hybrid H-matrix scheme, the architecture of LDPC decoder for DVB-S2 can be very practical and efficient. In addition, we show a new Variable Node processor Unit (VNU) architecture to reuse the VNU for various code rates and optimized block memory placement to reuse. We design a DVB-S2 LDPC decoder of code rate 1/2 usng the proposed architecture. We estimate the performance of the DVB-S2 LDPC decoder and compare it with other decoders.