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C/C복합체와 Graphite의 기계적 물성및 내산화성 증진
신동우,김법진 국립경상대학교 공과대학부설 첨단소재연구소 1995 尖端素材 Vol.5 No.-
본 연구에서는 탄소/탄소 복합체의 내산화성을 증진시키기 위하여 CVD법에 의한 SiC코팅과 PCS함침법을 응용하여 실험을 행하였다. 전자현미경으로 시편의 미세구조를 관찰한 결과 CVD법에 의해서는 표면에 SiC가 고르게 증착되었으며, 함침법에 의해서는 각 탄소 섬유의 표면에 PCS가 wetting된 후, SiC로의 전이가 잘 일어났음을 확인할 수 있었고, 이로 인하여 각 섬유들의 결합력을 증대시키고 기계적물성에 증진을 가져왔음을 확인하였다. PCS 함침된 탄소/ 탄소 복합체 시편은 함침되지 않은 시편에 비해 밀도는 25%, 곡강도 값은 3.5배, 내산화성은 2.8배가 증가하는 현격한 기계적 물성이 증가함을 보였다. 이러한 증가는 CVD법에 의해 코팅된 탄소/탄소 복합체 시편 보다도 우수한 기계적 성질을 보여주었다. Applicability of SiC coating through CVD process and PCS.(polycarbosilane) impregnation for the oxidation resistance and mechanical properties of C/C composite and graphite was studied. The SiC layer coated by CVD was deposited uniformly on the C/C composite, whereas the SiC converted from PCS impregnation wetted around individual carbon fiber. The PCS-impregnated C/C composite exhibited a significant increase of bending strength in comparison with as-received C/C composite. This increase in the mechanical property could be attributed to the high bonding strength between fibers due to an impregnated SiC phase. The PCS-impregnated C/C showed 25% improvement in density, 3.5 times higher MOR and 2.8 times higher oxidation resistance compared to the as-received C/C. The increments due to PCS impregantion were more effective than CVD process.
Zygosaccharomyces rouxii OB-03과 Pediococcus halophilus BH-90 의 첨가에 의한 低食鹽된장의 개발
류병호,채영주,박법규,김동규 慶星大學校 1991 論文集 Vol.12 No.2
For the deveolpment of new technique for low salty soybean paste, this study were carried out to the large scale fermentation of soybean paste after the addition of number of mass cells of Zygosaccharomyces rouxii OB-03 and Pediococcus halophilus BH-90. Inoclum size of Z. rouxii )B-03과 P. halophilus BH-90 was adapted to the rate of 1.8*10??/ml and 1.8*10⁴/ml in large scale fermentation of soybean paste. pH and lactic acid content were not markedly changed and, total and formol nitrogen was eluted high levels in 4% and 8% NaCl concentration during fermentation of soybean paste. Z. rouxii B-03 and P. halophilus BH-90 grew well at 4% NaCl than that of 8% and 12% NaCl concentrations and ethylalcohol also produced highest level at 4% NaCl. Glutamic acid and aspartic acid of free amino acid were eluted prodiminantly at 4% NaCl acid and also lactic were high content then that of others.
B$\Phi$rrensen Model Computation for Neutronic Benchmark Problems
Bub Dong Chung,Chang Hyo Kim,Chang Hyun Chung Korean Nuclear Society 1981 Nuclear Engineering and Technology Vol.13 No.2
B$\Phi$rrensen은 3차원적 노심분석에 긴 시간이 요구되는 유한차분법의 대안으로서 경수형 원자로의 전체출력분포를 계산하는데 한가지의 coarse mesh 방법을 제안하였다. 이 방법은 계산시간이 매우 짧은 것으로 알려져 있지만. 그 계산의 정확도에 대한 것은 아직까지 알려져 있지 않다. 본 논문에서는 B$\Phi$rrensen의 방법을 IAEA benchmark 문제와 RIS$\Phi$ benchmark 문제에 적용시켜서 계산시간과 정확도에 대해서 고찰하였다. 두 문제에서 노심-반사체와의 경계조건과 B$\Phi$rrensen의 모델상수들의 개선으로 출력분포 계산의 정확도를 상당히 높힐 수 있었다. B$\Phi$rrensen proposed a coarse mesh, three-dimensional one-and-half group diffusion scheme for computing the gross power distribution in light water reactors as an alternative to the conventional fine mesh finite difference approach in dealing with three dimensional problems, which require a prohibitively long computing time. The method reported takes extremely small execution time. However, its computational accuracy has not been investigated yet. The B$\Phi$rrensen method is revised in this work and both efficiency and accuracy are examined by applying it to IAEA benchmark problem and RIS$\Phi$ benchmark problem. It is found that two modifications on core-reflector boundary conditions and B$\Phi$rrensen's model constants may improve computational accuracy of power distribution calculation.
고리 1호기 외부 전원 상실사고에 의한 RELAP5/MOD2코드 모델 평가
Chung, Bub-Dong,Kim, Hho-Jung,Lee, Young-Jin Korean Nuclear Society 1990 Nuclear Engineering and Technology Vol.22 No.1
The Loss of Offsite Power Transient at 77.5% power which occurred on June 9, 1981 at the Kori Unit 1 PWR (Pressurized Water Reactor) is simulated using the RELAP5/MOD2 system thermal-hydraulics computer code. Major thermal-hydraulic parameters are compared with the available plant data. The comparison of the analysis results with the plant data demonstrates that the RELAP5/MOD2 code has the capability to simulate the thermal-hydraulic behaviour of PWRs under accident conditions of this type with accuracy, except the pressurizer pressure and level. The pressurizer pressure increase is sensitive to the in surge now it is believed that the interracial heat transfer in a horizontal stratified flow regime may be estimated low and the compression effect due to insurge flow may be high. In the nodalization sensitivity study it is found that S/G noding with junctions between bypass plenum and steam dome is preferred to simulate the S/G water level decreasing and avoid the spurious level peak at trubine trip.