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박관석,오윤근 제주대학교 환경연구소 1995 환경연구논문집 : 제주대 Vol.3 No.1
This study was performed about some major items such as Water Temperature, Salinity, pH, COD, T-N and PO_(4)^(3-)-P on to examine the water quality characteristics of ground-seawater in the eastern and the southern coasts of Cheju island from May to September in 1994. The water temperature in ground-seawater was about 17±1℃ in two coasts, but that in natual-seawater changed greatly amrclmg to season. COD in natual-seawater was 0.79-0.82mg/l. and was higher than that of ground-seawater bemg 0.53-0.54mg/l. The concentration of T-N and PO_(4)^(3-)-P in ground-seawater were hgher than those of natual-seawater: Average concentrations of T-N and PO_(4)^(3-)-P in ground-seawater were 24.72~26.79 ㎍-at/l and 1.15-1.16 ㎍-at/l respectively, whde those in natual-seawater were 3.54~3.65 ㎍-at/I and 0.32-0.34 ㎍-at/l respectively.
유한요소해석 및 실험에 의한 S45C 시편의 고주파 유도경화에 관한 연구
박관석,최진규,이석순 항공우주시스템공학회 2018 항공우주시스템공학회지 Vol.12 No.5
In this study, we proposed a high frequency induction hardening analysis method based on electromagnetic-thermal co-simulation. In the high frequency induction heating analysis, the results of the finite element analysis (FEA) (considering the change of the material property and the cooling factor according to the temperature) and those of the high frequency induction hardening experiment (using the S45C specimen) were compared. The hardness of the S45C specimens was measured using the micro Vickers hardness test to determine the depth of hardening. The measurement results were then compared with the results of FEA. The result of high frequency induction heating analysis showed that the temperature was more than 750 ℃, which is the A2 transformation point of S45C, while the temperature during quenching was below 200 ℃. The results showed that the difference of the depth of hardening between the FEA and the experiment is 0.2mm. 본 연구에서는 전자기-열 연동 모사를 기반으로 한 고주파 유도경화 해석방법을 제안하였다. 고주파 유도가열 해석 시 온도에 따른 재료의 물성치 변화 및 냉각 요소를 고려한 유한요소해석 및 이를 S45C시편을 이용한 고주파 유도경화 실험결과와 비교하였다. S45C시편을 마이크로 비커스를 사용하여 경도를 측정하여 경화깊이를 확인하였고 이를 유한요소해석 결과와 비교하였다. 고주파 유도가열 해석결과 온도는 S45C의 A2변태점인 750℃도 이상 가열되었으며, 급랭 시 200℃이하였다. 유한요소해석결과와 실험에 의한 경화깊이 차이는 0.2mm 수준인 것을 확인할 수 있었다.