• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.27-30
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• 2002

As computer capacity has been progressed continuously, the studies of the flow characteristics have been performing by the numerical methods actively. In this study, 3-dimensional unsteady incompressible Wavier-Stokes equation was solved by numerical method using the fractional step method with the fourth order compact pade' scheme to achieve high accuracy To validate the present code and algorithm, 3D flow-field around a cylinder was simulated. The drag coefficient and lift coefficient were computed and, then, compared with experiment. The present code will be tailored to LES simulation for more accurate turbulent flow analysis.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.448-455
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• 2020

The H.B. Robinson Unit 2 (HBR-2) pressure vessel dosimetry benchmark is an in- and ex-Reactor Pressure Vessel (RPV) neutron dosimetry benchmark based on experimental data from the HBR-2 reactor, a 2300-MW PWR designed by Westinghouse and put in operation in March 1971, openly available through the SINBAD Database at OECD/NEA data Bank. The goals of the present work were to carry out three-dimensional (3D) fixed source transport calculations in both Cartesian (X,Y,Z) and cylindrical (R,θ,Z) geometries by using the TORT-3.2 discrete ordinates code on very detailed 3D HBR-2 geometrical models and to test the latest broad-group coupled (47 neutron groups + 20 photon groups) working cross section libraries in FIDO-ANISN format with same structure as BUGLE-96, such as BUGJEFF311.BOLIB, BUGENDF70.BOLIB and BUGLE-B7. The results obtained with all the cited libraries were satisfactory and are here reported and compared.

• 정보처리학회논문지D
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• 제8D권3호
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• pp.273-284
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• 2001

실제로 사용되는 주소의 분석을 통해 한글주소의 해석방법을 제안하고, 제안한 주소해석 방법을 이용한 주소 검색시스템의 구현에 대하여 서술한다. 주소 상위 및 하위영역의 일치검증을 각각 순차적으로 수행하는 2단계 과정을 통해 최종 배달점에 대한 순로코드를 발생한다. 우편 번호와 주소 상위영역 일치검증 단계에서는 우편버호를 이용하여 주소사전에서 검색된 주소단어와 인식된 문자 후보들과의 비교를 통해 우편 번호를 검증하게 되며, 주소 상위영역과 주소 하위영역이 분리된다. 주소 상위영역 일치검증 과정의 성능향상을 위해 혼동행렬을 제안하고, 주소 인식결과에 혼동행렬을 적용하여 검증 성공률의 향상을 통해 혼동행렬의 유용성을 확인하였다. 주소 하위영역 검증은 번지정보와 건물명 정보를 이용하여 순로코드를 발생하였다. 부분적으로 완성된 광주와 부산지역의 DPF(Delivery Point File)와 레이블링된 데이터를 이용해 분석 가능한 주소에 대해 높은 정확도를 가지고 순로코드를 발생함을 확인할 수 있었다.

• 한국컴퓨터정보학회논문지
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• 제6권3호
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• pp.78-83
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• 2001

본 논문에서는 DS-CDMA시스템에서 다양한 페이딩 채널을 모델화 할 수 있는 나카가미-m 페이딩 환경을 고려하였다. 나카가미-m 페이딩을 고려한 시스템 모델링은 도시의 통신환경에서 다중경로를 갖는 이동 통신 채널에 적합한 모델로서 많이 사용되고 있다. 시스템은 적응형 직렬 탐색 PN 부호 획득기법을 사용하였으며 부호 획득 시간에 영향을 미치는 검출확률( $P_D$)과 오경보 확률( $P_FA$ )을 나카가미-m 페이딩 환경 하에서 유도하였다. 검출 확률 및 오경보 확률은 PN 부호 획득 시간을 결정하기 위한 결정변수로서 평균 획득 시간과 분산을 계산하기 위해 필수적으로 사용되며 컴퓨터 시뮬레이션 결과로부터 페이딩 채널 하에서의 PN부호 획득에 대한 평균 획득 시간과 분산을 해석함으로서 이동 통신 시스템의 H/W설계에 적용할 수가 있음을 확인하였다.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2670-2689
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• 2022

STREAM - a lattice transport calculation code with method of characteristics for the purpose of light water reactor analysis - has been developed by the Computational Reactor Physics and Experiment laboratory (CORE) of the Ulsan National Institute of Science and Technology (UNIST). Recently, efforts have been taken to develop a photon module in STREAM to assess photon heating and the influence of gamma photon transport on power distributions, as only neutron transport was considered in previous STREAM versions. A multi-group photon library is produced for STREAM based on the ENDF/B-VII.1 library with the use of the library-processing code NJOY. The developed photon solver for the computation of 2D and 3D distributions of photon flux and energy deposition is based on the method of characteristics like the neutron solver. The photon library and photon module produced and implemented for STREAM are verified on VERA pin and assembly problems by comparison with the Monte Carlo code MCS - also developed at UNIST. A short analysis of the impact of photon transport during depletion and thermal hydraulics feedback is presented for a 2D core also from the VERA benchmark.

• 한국유체기계학회 논문집
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• 제5권3호
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• pp.54-59
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• 2002

A commercial CFD code is used to compute the 3-D viscous flow field within the inlet flow concentrator of the newly developed AHU (Air Handling Unit). To improve the performance of the AHU, the inlet air needs to be gradually accelerated to the fan's annular velocity without causing turbulence or flow separation. Three major geometric parameters were selected to specify the inlet shape of the AHU. The performance of the AHU could be measured by the inlet and outlet flow uniformity and the total pressure loss through the inlet flow concentrator. Several numerical calculations were carried out to determine the influence of the geometric parameters on the performance of the AHU. The best geometric values were decided to have efficient inlet shape with analyzing CFD calculation results.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.67-74
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• 2004

Numerical analysis code has been developed for investigating the combustion characteristics in a slab heater of a steel mill company. Unsteady full 3-Dimensional behaviour can be predicted with the code. Premixed flame model is adopted for combustion phenomena. And eddy dissipation model is used for turbulent flow and non gray FVM method for radiation. Slab movement can be fully traced from entrance into heater until it's exit and computation is performed during that period. Code was validated by comparing the calculation results with experimental ones for the bench scale heater.

• Geomechanics and Engineering
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• 제16권1호
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• pp.21-34
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• 2018

Discontinuities considerably affect the mechanical and hydraulic properties of rock mass. These properties of the rock mass are influenced by the geometry of the discontinuities to a great extent. This paper aims to render an account of the geometrical parameters of several discontinuity sets related to the surrounding rock mass of Rudbar Lorestan Pumped Storage Power Plant powerhouse cavern making use of the linear and areal (circular and rectangular) sampling methods. Taking into consideration quite a large quantity of scanline and the window samplings used in this research, it was realized that the areal sampling methods are more time consuming and cost-effective than the linear methods. Having corrected the biases of the geometrical properties of the discontinuities, density (areal and volumetric) as well as the linear, areal and volumetric intensity accompanied by the other properties related to four sets of discontinuities were computed. There is an acceptable difference among the mean trace lengths measured using two linear and areal methods for the two joint sets. A 3D discrete fracture network generation code (3DFAM) has been developed to model the fracture network based on the mapped data. The code has been validated on the basis of numerous geometrical characteristics computed by use of the linear, areal sampling methods and volumetric method. Results of the linear sampling method have significant variations. So, the areal and volumetric methods are more efficient than the linear method and they are more appropriate for validation of 3D DFN (Discrete Fracture Network) codes.

• ETRI Journal
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• 제46권3호
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• pp.485-500
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• 2024

A hardware architecture is presented to decode (N, K) polar codes based on a low-density parity-check code-like decoding method. By applying suitable pruning techniques to the dense graph of the polar code, the decoder architectures are optimized using fewer check nodes (CN) and variable nodes (VN). Pipelining is introduced in the CN and VN architectures, reducing the critical path delay. Latency is reduced further by a fully parallelized, single-stage architecture compared with the log N stages in the conventional belief propagation (BP) decoder. The designed decoder for short-to-intermediate code lengths was implemented using the Virtex-7 field-programmable gate array (FPGA). It achieved a throughput of 2.44 Gbps, which is four times and 1.4 times higher than those of the fast-simplified successive cancellation and combinational decoders, respectively. The proposed decoder for the (1024, 512) polar code yielded a negligible bit error rate of 10^-4 at 2.7 E_b/N_o (dB). It converged faster than the BP decoding scheme on a dense parity-check matrix. Moreover, the proposed decoder is also implemented using the Xilinx ultra-scale FPGA and verified with the fifth generation new radio physical downlink control channel specification. The superior error-correcting performance and better hardware efficiency makes our decoder a suitable alternative to the successive cancellation list decoders used in 5G wireless communication.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 추계학술발표회 발표논문집
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• pp.201-202
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• 2004