• International Journal of Naval Architecture and Ocean Engineering
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• 제10권5호
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• pp.545-565
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• 2018

A numerical code is developed based on potential flow theory to investigate nonlinear sloshing in rectangular Liquefied Natural Gas (LNG) tanks under forced excitation. Using this code, internal free-surface elevation and sloshing loads on liquid tanks can be obtained both in time domain and frequency domain. In the mathematical model, acceleration potential is solved in the calculation of pressure on tanks and the artificial damping model is adopted to account for energy dissipation during sloshing. The Boundary Element Method (BEM) is used to solve boundary value problems of both velocity potential and acceleration potential. Numerical calculation results are compared with published results to determine the efficiency and accuracy of the numerical code. Sloshing properties in partially filled rectangular and membrane tank under translational and rotational excitations are investigated. It is found that sloshing under horizontal and rotational excitations share similar properties. The first resonant mode and excitation frequency are the dominant response frequencies. Resonant sloshing will be excited when vertical excitation lies in the instability region. For liquid tank under rotational excitation, sloshing responses including amplitude and phase are sensitive to the location of the center of rotation. Moreover, experimental tests were conducted to analyze viscous effects on sloshing and to validate the feasibility of artificial damping models. The results show that the artificial damping model with modifying wall boundary conditions has better applicability in simulating sloshing under different fill levels and excitations.

• 정보통신설비학회논문지
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• 제2권4호
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• pp.5-16
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• 2003

Parallel Coupler Access Encoder(PCAE)와 Parallel Coupler Access Decoder(PCAD)를 이용한 FO-CDMA(Fiber-Optic Code Division Multiple Access)시스템에서 광정합필터 특성을 실험을 통해 분석하였다. PCAE와 PCAD를 구성하고 있는 즉, 1xN splitter와 Nx1 combiner사이에 접속된 광지연선로의 길이비율을 광직교코드 생성알고리즘에 의해 결정하였고, 부/복호화 과정 및 시그템 성능을 peak to side-lobe ratio(PSR)를 구하여 기존에 제시된 결과와 비교하였다. 기존의 연구에서는 SCAE 및 SCAD를 이용하여 일차신호만을 고려하여 시스템의 성능을 분석하여 성능평가가 정확하지가 않았다. SCAE 및 SCAD는 커플러수를 증가함에 따라 여러 형태의 간섭신호들을 가지므로, 이러한 신호들이 시스템 성능을 현저히 열화 시킨다. 본 논문에서는 $\alpha$(coupling coefficient)값이 커질수록 PCAE와 PCAD를 이용한 PSR이 향상됨을 밝혔고 FO-CDMA 통신망의 성능을 개선하기 위해서는 SCAE와 분석 SCAD 구조보다는 PCAE와 PCAD 구조가 적합함을 제시하였다.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.635-641
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• 2016

Because of prohibitive data storage requirements in large-scale simulations, the memory problem is an obstacle for Monte Carlo (MC) codes in accomplishing pin-wise three-dimensional (3D) full-core calculations, particularly for whole-core depletion analyses. Various kinds of data are evaluated and quantificational total memory requirements are analyzed based on the Reactor Monte Carlo (RMC) code, showing that tally data, material data, and isotope densities in depletion are three major parts of memory storage. The domain decomposition method is investigated as a means of saving memory, by dividing spatial geometry into domains that are simulated separately by parallel processors. For the validity of particle tracking during transport simulations, particles need to be communicated between domains. In consideration of efficiency, an asynchronous particle communication algorithm is designed and implemented. Furthermore, we couple the domain decomposition method with MC burnup process, under a strategy of utilizing consistent domain partition in both transport and depletion modules. A numerical test of 3D full-core burnup calculations is carried out, indicating that the RMC code, with the domain decomposition method, is capable of pin-wise full-core burnup calculations with millions of depletion regions.

• 한국지반공학회논문집
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• 제24권1호
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• pp.15-23
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• 2008

본 연구에서는 개별요소법에 근거한 상용 수치해석 프로그램인 PFC2D를 이용하여 조립재인 쇄석의 전단특성 모델링을 수행하였다. 본 연구를 통하여 기존의 연속체 해석에서 고려하기 힘든 조립질 재료의 입도분포 및 공극, 불규칙한 형상을 모델링 할 수 있었다. 또한, 대형직접전단시험을 수행한 실험결과와 비교를 통해 입자특성과 관련한 조립질 재료의 고유 특성을 본 연구에서 모델링한 불연속체 모델링으로 모사할 수 있음을 알 수 있었다. 이러한 모델링 기법은 향후 다양한 입도 및 공극특성을 갖는 조립질 재료의 현장 강도 특성을 예측하는데 도움이 될 수 있다.

• ETRI Journal
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• 제32권6호
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• pp.972-975
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• 2010

In this letter, we consider the lossy coding of a non-uniform binary source based on GF(q)-quantized low-density generator matrix (LDGM) codes with check degree $d_c$=2. By quantizing the GF(q) LDGM codeword, a non-uniform binary codeword can be obtained, which is suitable for direct quantization of the non-uniform binary source. Encoding is performed by reinforced belief propagation, a variant of belief propagation. Simulation results show that the performance of our method is quite close to the theoretic rate-distortion bounds. For example, when the GF(16)-LDGM code with a rate of 0.4 and block-length of 1,500 is used to compress the non-uniform binary source with probability of 1 being 0.23, the distortion is 0.091, which is very close to the optimal theoretical value of 0.074.

• 대한의용생체공학회:의공학회지
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• 제14권4호
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• pp.355-364
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• 1993

Clinical laboratory order communication system was developed to run fast and effective laboratory tests at the Chungbuk National University Hospital. The present system incorporated with the main Hospital Management Information System accepts :aboratory orders, classifies them based on the predefined logical system, and outputs various practical informations for the user. These assist sample taking, sample management, and work plan organization. A special care was taken to the sample management by introducing the bar code system. The system was written in the INFOS hierarchical database and COBOL, and is currently in the practical use for both in - and out-ward patients. The present system enabled fast and effective data communication as well as reducing the time and man power indispensable when the manual slips are used for order communication.

• Structural Engineering and Mechanics
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• 제34권4호
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• pp.475-490
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• 2010

It is the intention of this study to synthesize the effects of double-edge cracks on the dynamic characteristics of a beam. The stiffness matrix is first determined for a Timoshenko beam containing two same-line edge cracks. The presented model is then developed for elements with two parallel double-sided cracks, considering the interaction between the stress fields of adjacent cracks. Finally, a finite element code is implemented, to examine the influence of depth and location of double cracks, on the natural frequencies of the damaged system.

• ETRI Journal
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• 제27권2호
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• pp.231-234
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• 2005

This letter proposes a new embedded speech coding structure based on the Adaptive Multi-Rate Wideband (AMR-WB) standard codec. The proposed coding scheme consists of three different bitrates where the two lower bitrates are embedded into the highest one. The embedded bitstream was achieved by modifying the algebraic codebook search procedure adopted for the AMR-WB codec. The proposed method provides the advantage of scalability due to the embedded bitstream, while it inevitably requires some additional computational complexity for obtaining two different code vectors of the higher bitrate modes. Compared to the AMR-WB codec, the embedded coder shows improved speech qualities for two higher bitrate modes with a slightly increased bitrate caused by the decreased coding efficiency of the algebraic codebook.

• 대한유전성대사질환학회지
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• 제5권1호
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• pp.108-115
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• 2005

Inherited metabolic diseases (IMD) comprise a large class of genetic diseases involving disorders of metabolism. The majorities are due to defects of single genes that code for enzymes that facilitate conversion of various substances into others. Because of the multiplicity of conditions, many different diagnostic tests are used for screening of IMD. Molecular genetic diagnosis is the detection of pathogenic mutations in DNA and/or RNA samples and is becoming a much more common practice in medicine today. The purpose of molecular genetic testing in IMD includes diagnostic testing, pre-symptomatic testing, carrier screening, prenatal diagnosis, preimplantation testing, and population screening. However, because of the complexity, difficulty in interpreting the result, and the ethical considerations, an understanding of technical, conceptual, and practical aspects of molecular genetic diagnosis is mandatory.

• International Journal of Concrete Structures and Materials
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• 제11권1호
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• pp.151-159
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• 2017

The action of rainwater on reinforced concrete walls has led to an erosion phenomenon. The erosion is very apparent when the walls are inclined. This phenomenon is studied on a real site characterized by different architectural forms. The site dates back to the seventies; it was designed by the architect, modeler of concrete, Oscar Nie Meyer. On this site, the erosion has damaged the cover of the reinforcements and reduced its depth. In this research work, a method of quantification of the erosion is developed. Using this method, the amount of mass loss by erosion was measured on imprints taken from the site. The results are expressed by the rate of mass loss by erosion; they are associated to the height and the inclination of the walls. Moreover, laboratory analysis was carried out on samples taken from the site. From this study, it is recommended to consider the erosion, in any building code, to determine the cover thickness.