• Nuclear Engineering and Technology
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• 제56권3호
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• pp.959-965
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• 2024

The High Temperature Test Unit (HTTU) was an experimental set-up to conduct separate and integral effects tests of the Pebble Bed Modular Reactor (PBMR) core. The annular core consisted of a randomly packed bed of uniform spheres. Natural convection tests using both nitrogen and helium, and forced convection tests using nitrogen, were conducted. The maximum material temperature achieved during forced convection testing was 1200 ℃. This paper presents the numerical analysis of the flow and temperature distribution for a forced convection test using 3D CFD as well as a 1D systems-CFD computer code. Several modelling approaches are possible, ranging from a fully explicit to a semi-implicit method that relies on correlations of their associated phenomena. For the comparison between codes, the analysis was performed using a porous media approach, where the conduction and radiative heat transfer were lumped together as an effective thermal conductivity and the convective heat transfer was correlated between the solid and gas phases. The results from both codes were validated against the experimental measurements. Favourable results were obtained, in particular by the systems-CFD code with minimal computational and time requirements.

• 국제초고층학회논문집
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• 제2권3호
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• pp.257-269
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• 2013

This study presents the development of an advanced multiple database-enabled design module for high-rise buildings (DEDM-HR), which seamlessly pools databases of multiple high frequency base balance measurements from geographically dispersed locations and merges them together to expand the number of available building configurations for the preliminary design. This feature offers a new direction for the research and professional communities that can be utilized to efficiently pool multiple databases therefore expanding the capability of an individual database and improving the reliability of design estimates. This is demonstrated, in this study, by the unprecedented fusion of two major established databases, which facilitates interoperability. The DEDM-HR employs a cyberbased on-line framework designed with user-friendly/intuitive web interfaces for the convenient estimation of wind-induced responses in the alongwind, acrosswind and torsional directions with minimal user input. In addition, the DEDM-HR embeds a novel feature that allows the use of wind characteristics defined in a code/standard to be used in conjunction with the database. This supplements the provisions of a specific code/standard as in many cases guidance on the acrosswind and torsional response estimates is lacking. Through an example, results from several international codes and standards and the DEDM-HR with the embedded features are compared. This provision enhances the scope of the DEDM-HR in providing an alternative design tool with nested general provisions of various international codes and standards.

• 한국통신학회논문지
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• 제22권7호
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• pp.1427-1436
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• 1997

Turbo codes, decoded through an iterative decoding algorithm, habe recently been shown to yidel remarkable coding gains close to theoretical limits in the Gaussian channel environment. This thesis presents the performance of Turbo code through the computer simulation. The performance of modified Turbo code is compared to that of the conventional Turbo codes. The modified Turbo code reduces the time delay in decoding with minimal effect to the performance for voice transmission sytems. To achieve the same performance, random interleaver the size of which is no less than the square root of the original one should be used. Also, the modified Turbo code is applied to MC-CDMA system, and its performance is analyzed under the Rayleigh Fading channel environment. In Rayleigh fading channel environment, due to the amplitude distortion caused by fading, the interleaver of the size twice no less than that in the Gaussian channel enironment was required. In overall, the modified Turbo code maintained the performance of the conventional Turbo code while the time delay in transmission and decoding was reduced at the rate of multiples of two times the squared root of the interleaver size.

• 한국정밀공학회지
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• 제22권4호
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• pp.121-127
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• 2005

There is a necessity for the communication between intelligent robots and human beings because of wide spread use of them. Gesture recognition is currently being studied in regards to better conversing. On the basis of previous research, however, the gesture recognition algorithms appear to require not only complicated algorisms but also separate training process for high recognition rates. This study suggests a gesture recognition algorithm based on computer vision system, which is relatively simple and more efficient in recognizing various human gestures. After tracing the hand gesture using a marker, direction changes of the gesture trajectory were analyzed to determine the simple gesture code that has minimal information to recognize. A map is developed to recognize the gestures that can be expressed with different gesture codes. Through the use of numerical and geometrical trajectory, the advantages and disadvantages of the suggested algorithm was determined.

• Journal of Microbiology and Biotechnology
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• 제6권5호
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• pp.315-320
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• 1996

The role of glyoxylate bypass in a lysine-producing Corynebacterium lactofermentum strain was analyzed. Unlike the wild type, the strain expressed enzymes of glyoxylate bypass during growth in the fermentation broth containing glucose as the carbon source. To evaluate the importance of glyoxylate bypass in the strain, we disrupted chromosomal aceA by using a cloned fragment of the gene. Site-specific disruption of aceA which codes for the isocitrate lyase, the first enzyme of the bypass, was confirmed by Southern blot analysis. The aceA mutant strain completely lost isocitrate lyase activity and ability to grow in a minimal medium containing acetate as the sole carbon source. The mutant strain was similar to its parental strain in growth characteristics and produced comparable amounts of lysine in shake flasks containing glucose as the carbon source. The amount of oxaloacetate accumulated in the fermentation medium was similar for both strains, suggesting that expression of glyoxylate bypass does not necessarily lead to the increase in intracellular oxaloacetate. These data clearly demonstrate that glyoxylate bypass does not function as one of the routes of carbon supply for lysine production in the strain. It appears that the leakiness of the glyoxylate bypass in the strain might be the result of a secondary mutation which arose during previous strain development by random mutagenesis.

• 한국통신학회논문지
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• 제38A권6호
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• pp.459-464
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• 2013

본 연구에서는 이차원 인접 심볼간 간섭(2D ISI) 및 인접 페이지간 간섭 (IPI)을 줄이는 홀로그래픽 저장장치를 위한 이차원 변조부호를 선택하는 문제를 고려한다. 변조부호 선택문제는 목적함수로 코드내부와 코드 상호간 인접심볼값의 차이를 최소화하고, 제약식으로는 사용된 심볼의 분포가 균등하며, 최소 해밍거리 조건이 주어진 이차정수계획법 모형으로 수식화되었다. 선택된 코드워드에서 고립된 픽셀의 발생여부를 검색하는 모형은 정수계획법 모형으로 수식화되었다. 제안된 모형들은 4-레벨 6/8 코드 및 2-레벨 6/8 코드에 적용되어 성능을 계산하였다.

• Steel and Composite Structures
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• 제29권2호
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• pp.175-186
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• 2018

The plastic hinge method and the plastic zone method are extensively adopted in displacement-based elements and force-based elements respectively for second-order inelastic analysis. The former enhances the computational efficiency with relatively less accurate results while the latter precisely predicts the structural behavior but generally requires more computer time. The displacement-based elements receive criticism mainly on plasticity dominated problems not only in accuracy but also in longer computer time to redistribute the forces due to formation of plastic hinges. The multi-element-per-member model relieves this problem to some extent but will induce a new problem in modeling of member initial imperfections required in design codes for direct analysis. On the contrary, a force-based element with several integration points is sufficient for material yielding. However, use of more integration points or elements associated with fiber section reduces computational efficiency. In this paper, a new force-based element equipped with stress-resultant plasticity model with minimal computational cost is proposed for second-order inelastic analysis. This element is able to take the member initial bowing into account such that one-element-per-member model is adequate and complied with the codified requirements of direct analysis. This innovative solution is new and practical for routine design. Finally, several examples demonstrate the validity and accuracy of the proposed method.

• 대한기계학회논문집A
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• 제27권11호
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• pp.1958-1966
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• 2003

Three-axis CNC surface machining entails a series of processes including rough cutting, intermediate cutting and finish cutting for a reference surface defined in CAD/CAM. This study is targeting development of an integrated NURBS surface interpolator that can incorporate rough, intermediate and finish cutting processes. In each process, volume to be removed and cutting condition are different according to the shape of a part to be machined and the reference surface. Accordingly, the proposed NURBS surface interpolator controls motion in real-time optimized for the machining conditions of each process. In this paper, a newly defined set of G-codes is proposed such that NURBS surface machining through CNC is feasible with minimal information on the surface composition. To verify the usefulness of the proposed interpolator, through computer simulations on NURBS surface machining, total machining time, size of required NC data and cutting force variations are compared with the existing method.

• 한국통신학회논문지
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• 제32권10C호
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• pp.1042-1050
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• 2007

본 논문은 머신 기술 언어를 이용하여 전력 소모가 최소화된 임베디드 코어 자동 생성 시스템의 설계에 대해 기술한다. 머신 기술 언어를 사용하여 어플리케이션에 적합한 임베디드 코어를 빠른 시간에 설계하기 위해 어플리케이션 실행시 동적 전력 소모가 최소화된 코어를 생성하는 시스템을 구축하였다. 제안된 시스템은 각 인스트럭션의 파이프라인 스테이지의 행위 정보로부터 파이프라인 해저드를 찾아내며 처리하는 능력을 가진 임베디드 코어를 생성한다. 생성된 코어는 파워 소모가 최소화되게 만들어져 있다. 자동 생성 시스템의 검증을 위해 ARM9, MIPS R3000에 대해 SMDL로 기술하고 전력 최적화 과정을 거쳐 HDL 코드를 자동 생성하였으며, 어플리케이션에 대해 시뮬레이션을 수행하여 소모되는 전력을 측정하였다. 실험 결과로 생성된 프로세서는 정확한 동작을 수행하였고, 어플리케이션과 생성된 코어에 따라 동적 전력 소모가 $20%{\sim}40%$ 줄어드는 것을 확인하였다.

• Structural Engineering and Mechanics
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• 제73권4호
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• pp.397-405
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• 2020

In this study size optimization of large-scale dome structures with dynamic constraints is presented. In the optimal design of these structure, the Jaya algorithm is used to find minimal size of design variables. The design variables are the cross-sectional areas of the steel truss bar elements. To take into account the constraints which are the first five natural frequencies of the structures, the finite element analysis is coded in Matlab programs using eigen values of the stiffness matrix of the dome structures. The Jaya algorithm and the finite elements codes are combined by the help of the Matlab - GUI (Graphical User Interface) programming to carry out the optimization process for the dome structures. To show the efficiency and the advances of the Jaya algorithm, 1180 bar dome structure and the 1410 bar dome structure were tested by taking into the frequency constraints. The optimal results obtained by the proposed algorithm are compared with those given in the literature to demonstrate the performance of the Jaya algorithm. At the end of the study, it is concluded that the proposed algorithm can be effectively used in the optimal design of large-scale dome structures.