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SA 508c-3강의 고온에서 J-R 및 Tmat의 평가
주원식,임만배 東亞大學校 1998 東亞論叢 Vol.35 No.-
In this study, the J-Resistance Curve and material tearing modulus of SA508-C3 steel, which is one of the used nuclear pressure vessel steel, were measured at room temperature, 200℃ and 300℃ according to load ratio analysis and ASTM E813. ASTM E1152, respectively. It was observed that J-R curve and Tmat value decreased as the temperature level invreased. Applicability of Tj proposed by Paris et al as an instability paramter for ductile material is investigated. The results are the Tj parameter may be used as a crack instability parameter.
SUS 304鋼의 크리이프溫度領域에 관한 時間依存型 및 싸이클依存型 疲勞크랙 傳播
周原植 동아대학교 공과대학 부설 한국자원개발연구소 1984 硏究報告 Vol.8 No.1
The low-cycle fatigue creak growth behavior of SUS 304 Stainless steel was investigated at 650℃ by the nonlinear fracture mechanics. Crack Propagation can be separated into cycle-dependent and time-dependent, the former is correlated with △J_(f), J-intergral range and the latter is correlated with J', modified J integral. Transition from cycle-dependent to time-dependent crack growth was successfully predicted using the β hypothesis, which was proposed by the authors on the basis of an analysis on the interaction of elastic and creep strain. To investigate the reliability of β-hypothesis, experimenting by the change of stress-level, stress rate and frequency, following conclusions were obtained. 1) High temperature fatigue crack propagation was separated into cycle-dependent and time-dependent. 2) Transition of crack propagation was predicted by △J_(c)/△J_(f) or β. 3) Lower limit in cycle-dependent crack propagation was obtained.
高溫低싸이클 疲勞크랙전파에 미치는 過度的 크리이프變形擧動의 影響
周原植,韓根祚 동아대학교 공과대학 부설 한국자원개발연구소 1985 硏究報告 Vol.9 No.1
Considering the elastic strain and the creep strain at high temperature low cycle fatigue, together, we could find that the experimental modified J integral, J'ex is larger than the theoretical value, J'a. To investigate which effects this enlargement have on the crack propagation in the creep-fatigue interaction range, the high temperature low cycle fatigue crack experiment was accomplished using CN specimens. The results are as follows. 1. The enlargement of J'ex is not considerable at R=0 but at R=-1 it is considerable. 2. J'ex with low stress holding time is 2-10 times larger than the one without holding time. 3. In case of no holding time, the enlargement of J'ex has effects on the crack crack propagation rate at R=-1, but at R=0 a certain factor having no effects was found out.
주현수,김진,박종천,정원석,이원교,이우범 國立 麗水大學校 環境問題硏究所 2000 環境硏究論文集 Vol.3 No.-
On filtrated and autoclaved water samples from Lake Jinyang, algal growth potential(AGP) test using Selenastrum capricornutum Printz were performed from February, 1999 to October, 1999 in order to assess fertility potential of the lake and to identify possible limiting nutrients. Algal growth potentials of the filtrated and filtrated after autoclaved samples were 0.018 ㎎/ℓ ~9.965 ㎎/ℓ and 0.018 ㎎/ℓ ~28.788㎎/ℓ respectively during surveyed period. AGP of the filtrated after autoclaved were higher than those of the filtrated only except some specific stations. The points of maximum growth were measured after addition of N, P and unenriched samples (control). The limiting factor was nitrogen only at site 5 in spring and phosphate appeared to be the major limiting nutrients in spike test throughout the year, especially during spring and autumn. Accoding to trophic level by Sudo(1980), the water quality of lake Jinyang were estimated mesotrophic at site 2, 4, 5, 6 in spring, at site 3, 6 in summer and at site 6 in autumn but all other sites were oligotrophic. But it is suggested that if we have not manigement of lake Jinyang, the water quality is possible to convert eutrophic.
주현수,김진,박종천,정원석,송현철,이용탁,이우범 國立麗水大學校 環境問題硏究所 2004 環境硏究論文集 Vol.6 No.-
We carried out a study on phytoplankton community at Owon stream, Jeollabukdo, Korea. The author have examined 83 taxa of the phytoplankton from researched area. These were composed of 5 classes, 11 orders, 21 families, 44 genera, 79 species, and 9 varieties. The composition of occurrence species were as follows: green algae are 48.2%, diatoms are 33.7%, blue green algae are 10.8% and etc(7.3%). Dominant species were Chlamydomonas angulosa, Pandorina morum, Coelastrum microporum, Scenedesmus quadricauda, Staurastrum gracile, Melosira varians, Me. italica, Synedra ulna, Sy. acus, Cocconeis placentula, and Cymbella tumida. The standing crops varied from 1,650cells/ℓ to 47,000cells/ℓ. Phytoplankton density of Owon stream were lower about 8.6 times to a 1,531 times than those of other lakes and rivers in Korea. So, to preserve the water quality in Owon stream we have to manage continuously on the nitrogen and phosphorus.
주현수,김진,이원교,이우범 國立 麗水大學校 환경문제硏究所 2001 環境硏究論文集 Vol.4 No.-
A survey of phytoplankton community was carried out seasonally from January to September, 2000 at Seomjin river, Jeollanamdo, Korea. The author have examined 158 taxa of the phytoplankton from researched area. These were composed of 6 classes, 14 orders, 33 families, 75 genera, 145 species, and 13 varieties. The composition of occurrence species were as follows: green algae are 42.4%, diatoms are 39.2%, blue green algae are 12.0% and etx(6.4%). Dominant species were Scenedesmus dimorphus, Melosira varians, M,granulata, Fragilaria constuns, Asterionella grasillima, Synedra ulna, Synedra acus, Cymbella affinis, Nitzschia sigma, N.seriata, frustual. The standing crops varied from 2.304 cell/ℓ to 13.056 cells/ℓ in winter and spring, and appeared from 234 cells/ℓ to 6784cell/ℓ in summer and autumn. It was different than general dimictic lake in temperate zone has seasonal change of standing crop. Phytoplankton density of Seomjin river were lower about ten times to a five thousand tines than those of other lakes and river in Korea. So, to preserve the water quality in Seonjin river we have to manage continuously on the nitrogen and phosphorus.