• Nuclear Engineering and Technology
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• 제35권6호
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• pp.529-536
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• 2003

The objective of this study is to investigate the reorientation of hydrides with applied stress intensity factor, the peak temperature and the time when to apply the stress intensity factor in a Zr-2.5Nb pressure tube during its thermal cycle treatment. Cantilever beam (CB) specimens with a notch of 0.5 mm in depth made from the Zr-2.5Nb tube were subjected to electrolytic hydrogen charging to contain 60 ppm H and then to a thermal cycle involving heating to the peak temperature of either 310 or $380^{\circ}C$, holding there for 50 h and then cooling to the test temperature of $250^{\circ}C$. The stress intensity factor of either 6.13 or $18.4\;MPa\sqrt{m}$ was applied at the beginning of the thermal cycle, at the end of the hold at the peak temperatures and after cooling to the test temperature, respectively. The reorientation of hydrides in the Zr-2.5Nb tube was enhanced with the increased peak temperature and applied stress intensity factor. Furthermore, when the CB specimens were subjected to $18.4\;MPa\sqrt{m}$ from the beginning of the thermal cycle, the reoriented hydrides occurred almost all over the Zr-2.5Nb tube, surprisingly suppressing the growth of a DHC crack. In contrast, when the CB specimens were subjected to the stress intensity factor at the test temperature, little reorientation of hydrides was observed except the notch region, leading the Zr-2.5Nb to grow a large DHC crack. Based on the correlation between the reorientation of hydrides and the DHC crack growth, a governing factor for DHC is discussed along with the feasibility of the Kim's DHC model.

• 한국잡초학회지
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• 제5권2호
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• pp.103-108
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• 1985

Echinochloa colona(L.) Link 발아(發芽) 및 생장(生長)에 미치는 pH, 염도(鹽度), 파종심도(播種深度) 및 수분압박(水分壓迫)의 영향(影響)을 조사(調査)하였다. 발아(發芽)는 pH 10에서 현저히 감소(減少)되었으나, 유아(幼芽)의 길이는 시험(試驗)된 pH의 범위내(範圍內)에서 유의차(有意差)가 없었다. 염분농도(鹽分濃度) 0.1% 이하(以下)에서 발아(發芽)에 영향(影響)을 미치지 않으나, 0.5%에서 감소(減少)되었다. 염분농도(鹽分濃度) 1.0%에서는 유아신장(幼芽伸長)에 영향(影響)을 미치지 않았다. 파종심도(播種深度)가 깊어짐에 따라 발아율(發芽率)은 현저히 감소(減少)되지만, 파종심도(播種深度)에 관계(關係)없이 엽초(葉鞘)마디(coleoptilar node)는 항상 지표면(地表面) 바로 밑에서 형성(形成)되었다. 수분(水分)포텐셜이 -4.6 bars에서 발아(發芽)는 감소(減少)되고 지연(遲延)되었으며, -9.8 bars의 수분(水分)포텐셜에서는 발아(發芽)되지 않았다. 토양(土壤)의 수분압박(水分壓迫)은 초장(草長)을 감소(減少)시키고, 출수(出穗)를 지연(遲延)시켰으며, 종자생산(種子生産)을 감소(減少)시켰다.

• 한국컴퓨터정보학회논문지
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• 제3권2호
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• pp.1-6
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• 1998

소프트웨어 개발 과정에서 신뢰성 평가는 대단히 중요하다. 테스트 단계를 구분하지 않은 소프트웨어의 신뢰도 평가˙분석의 결과는 신뢰성이 결여될 수 있다. 따라서 본 논문에서는 이러한 문제점을 해결하기 위해 테스트 단계를 구분하여 신뢰성 평가에 관한 연구를 하였다. 이를 위해 단위 테스트(Unit Test), 통합 테스트(Integration Test), 확인 테스트(Validation Test), 시스템 테스트(System Test)에서 발견된 결함 데이터를 이용하여 소프트웨어 신뢰도 성장 모델(Software Reliability Growth Model : SRGM)인 지수형, 지연 S자형, 습숙 S자형 SRGM에 적용하였다. 그 결과 단위 테스트에서는 습숙 S자형, 통합 테스트에서는 지연 S자형, 확인테스트에서는 지연 S자형, 시스템 테스트에서는 지수형 SRGM이 가장 적합한 것임을 입증하였으며, 신뢰성 평가 척도인 파라미터 추정, 편차 자승합, 기대잔존 결함수 등에서 본 연구의 결과가 기존의 방법보다 우수함을 보였다.

• 한국세라믹학회지
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• 제30권6호
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• pp.433-440
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• 1993

The bioactivity of glasses in the CaO-SiO2 system and CaO-P2O5-SiO2 system with less than 10mol% of P2O5 was investigated by in vitro test in simulated body flood(SBF). The formation of Ca.P film and hydroxyapatite on the surface of glasses after in vitro test was analysed by X-ray photoelectron spectoscopy (XPS), fourier transform infrared reflection spectroscopy (FT-IRRS), energy dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) observation. In the early stage of Ca.P film formation after in vitro test for CaO-SiO2 and CaO-P2O5-SiO2 glasses, the rate of Ca.P film formation on the surface of the glasses was dependent of structural parameter (Y) evaluated from the glass composition. First, in the case of the glasses having Y value below 2, Ca.P film and SiO2-rich layer were formed simultaneously, and there were no differences of the rate of Ca.P film formation in terms of the Y values. Second, in the case of the glasses having Y value above 2, the SiO2-rich layer was formed, and then Ca.P.Si mixed layer was formed in the silica gel structure of the SiO2-rich layer, and finally the Ca.P film on the surface of SiO2-rich layer. The rate of Ca.P film formation delayed as the Y values increased. The rate of hydroxyapatite formation of glasses (the rate of transformation from Ca.P film to hydroxyapatite) seems to be propotional to the rate of Ca.P film formation and Y value. The rate of hydroxyapatite formation of glasses belonging to the second group was delayed as structural parameter increased, and the hydroxyapatite crystal showed spherical growth in the early reaction stage, and then showed silkworm-like linear growth as the reaction time increased.

• 대한한방내과학회지
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• 제24권2호
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• pp.315-328
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• 2003

This study was performed to investigate the effect of Bunsimgieum on antitumor effect after sarcoma-180 cells transplantation into peritoneal cavity or left groin and immune responses on the depressed immunity induced by methotrexate in mice. The Bunsimgieum extract of 10mg/kg was orally administered 14 days for antitumor effects and 21 days for immune responses. 50% inhibitory concentration($IC_{50}$) of SUN-1, SUN-C4, and SUN-396 cancer cell, mean sunvival days and body weight of tumor bearing mice, and growth of tumor mass for antitumor effect; delayed type hypersentivity, hemagglutinin titer, hemolysis titer, rosette forming cells, natured killer cell activity, lymphocyte transformation, productivity of interleukin-2, and phagocytic activity for their immune responses were measured in ICR mice. Significance in antitumor effect is noted in the enlongation of mean life days and inhibition of tumor growth(p<0.01, respectively). Significance of immune responses is also noted in hemolysis titer, lymphocyte transfumotion, IL-2 productivity, phagocytic activity, and natural killer cell activity at E/T ratio 100:1(p<0.01, respectively). Significant in rosette cell formation was seen at dosage of 20mg/kg(p<0.01). However, Difference of body weight as antitumor effect, delayed type hypersensitivity, and hemagglutinin titer were not shown significantly. According to the above results, it could be suggested that Bunsimgieum has prominent antitumor and immunity enhancing effect.

• 한국작물학회지
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• 제26권4호
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• pp.337-343
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• 1981

단교잡종 옥수수민 수원19호를 3월 26일부터 7월 9일까지 15일 간격으로 8회 파종하여 파종기가 종실 및 싸일레이지 수량과 생육기간에 미치는 영향을 보면 다음과 같다. 1. 파종기가 빠를수록 파종에서 출현까지 일수가 길어지나 출현율은 65%인 3월 26일의 극조식을 제외하면 4월 9일 이후의 파종구는 출현율이 80% 이상이었다. 2. 종실수량은 4월 25일까지는 파종기간에 차이가 없었으로 그 이후는 파종이 지연될수록 자수를 발달시키지 못하는 포기의 증가와 수당잎수의 감소로 수량이 감소하였다. 3. 건물중으로 표시한 싸일레이지 수량은 5월10일 파종까지는 차이가 없었으나 그 이후는 파종이 지연될수록 수량, 건물비율, 종실중/전건물중 비율이 현저히 감소하였다. 4. 파종에서 출사까지 일수는 파종류가 지연됨에 따라 108 일에서 52일까지 감소하였으나 유효적산 온도로 표시하면 파종기에 관계없이 비슷하였으며 평균 815$^{\circ}C$이었다. 5. 종실 및 싸일레이지 생산을 목표로 할 때 등숙기간은 다수확을 위한 파종한계기 이내에 파종하면 각각 44 및 40~42일 이었으나 다수확을 위한 파종만한기 이후에 파종하면 성숙까지 일수는 헌저히 증가되었다. 그러나 유효적산온도로 표시하면 파종에 상관없이 종실용은 평균 697$^{\circ}C$ 싸일레이지용은 651$^{\circ}C$이었다.

• 한국해양공학회지
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• 제23권2호
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• pp.69-73
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• 2009

The objective of this study was to obtain a better understanding of the delayed hydride cracking (DHC) of Zr-2.5Nb alloy. The DHC model has some defects: first, it cannot explain why the DHC velocity (DHCV) becomes constant regardless of an applied stress intensity factor, even though the stress gradient is affected by the applied stress intensity factor at the notch tip. Second, it cannot explain why the DHCV has a strong dependence on the method of approaching the test temperature by a cool-down or a heating-up, even under the same stress gradient, and third, it cannot predict any hydride size effect on the DHC velocity. The DHC tests were conducted on Zr-2.5Nb compact tension specimens with the test temperatures reached by a heating-up method and a cool-down method. Crack velocities were measured in hydrided specimens, which were cooled from solution-treatment temperatures at different rates by being furnace-cooled, water-quenched, and liquid nitrogen-quenched. The resulting hydride size, morphology, and distributions were examined by optical metallography. It was found that fast cooling rates, which produce very finely dispersed hydrides, result in higher crack growth rates. This different DHC behavior of the Zr-2.5Nb tube with the cooling rate after a homogenization treatment is due to the precipitation of the $\gamma$-hydrides only in the water-quenched Zr-2.5Nb tube. This experiment will provide supporting evidence that the terminal solid solubility of a dissolution (TSSD) of $\gamma$-hydrides is higher than that of $\delta$-hydrides.

• 한국작물학회지
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• 제45권3호
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• pp.185-189
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• 2000

영남내륙지역에서 직파재배용 벼 품종인 동안벼, 대산벼, 농호벼, 호안벼, 광안벼를 공시하여 적정 파종기를 구명하기 위해 시험한 결과를 요약하면 다음과 같다. 1 출아소요기간은 5월 30일 파종기에서 12일로 가장 짧았으며, 입모수는 5월 10일과 5월 30일에서 많았다. 2. 4월 30일과 5월 10일 파종에서 수수가 많아 10a당 쌀수량이 485-494 kg으로 다른 시기 보다 증수되었으며, 품종별로는 5월 10일 파종의 동안벼가 513 kg으로 가장 많았다. 3. 완전미비율은 5월 10일 파종이 90.4%로 가장 높았고, 5월 30일 파종은 83.1%로 가장 낮았다. 4. 품종별 완전미비율은 5월 10일 파종한 대산벼에서 92.1%로 가장 높았으며, 4월 20일과 5월 30일 파종한 광안벼에서 각각 동할미 및 청미의 비율이 높아 완전미비율은 78.8%로 낮았다. 5. 회귀식에 의한 적정파종기는 호안벼는 5월 10일, 동안벼는 5월 3일, 농호벼는 5월 8일, 광안벼는 5월 1일, 대산벼는 5월2일이었다.

• 한국초지조사료학회지
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• 제12권4호
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• pp.246-252
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• 1992

In order to reduce the problems from overlapping between rye harvest and maize seeding dates, and also to improve the growth, productivity and nutritive value of rye (Secale cereale L.), an experiment was carried out to determine the variety effect of rye on the forage production system, and seeding date effect on the yield and quality of rye. The experiment was conducted in the forage testing field of S.N.U., Suweon, from September 1988 to May 1989. The dry matter and in vitro digestible dry matter yields of rye harvested 14 April were 5.2 t and 4.6 t/ha with an early maturing rye variety, Winter more, but 3.1 t and 2.8 t/ha were obtained with a late maturing rye variety, Kodiak. When seeding date was delayed, a significant decrease in dry matter yield was observed. ADF and NDF contents, and IVDMD of an early maturing rye, Winter more, harvested 14 April were 25.6, 44.8 and 81.9 %, but those of a late maturing rye, Kodiak, were 21.1, 39.5 and 88.9 %, respectively. ADF and NDF contents of rye were increased as the seeding date was delayed, but ail forage ryes from different seeding dates as well as varieties were recorded as the 1st grade proposed by market hay grades. The dry matter and in vitro digestible dry matter yields of rye harvested at 80 %heading stage were significantly decreased as delayed seeding date, but no significant differences were found between early and late maturing varieties. No differences in ADF and NDF contents, and IVDMD of the rye harvested at 80% heading stage were found among the treatments, but all forage ryes were evaluated as the 4 th grade proposed by market hay grades.

• 한국작물학회지
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• 제45권4호
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• pp.272-275
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• 2000

Winter green manure crops including legume increase grain yield of subsequent crop and substitute N fertilizer requirement with organic-No Hairy vetch grows vigorously and can provide N-rich green manure for corn with its soil incorporation after wintering. But, grain yield of corn as succeeding crop would be reduced if its planting time is delayed until late spring. This experiment was carried out to find the proper incorporation time of hairy vetch green manure and planting time of subsequent corn in cropping system with winter hairy vetch(green manure)-summer corn. Hairy vetch was incorporated into soil at a ten-day interval between April 10 and May 10 and corn was planted at 5 days after each hairy vetch incorporation. Soil nitrate concentration on April 10 and 20 in hairy vetch plot was slightly lower than that at winter fallow. Above-ground dry matter and organic-N of hairy vetch increased linearly with delayed hairy vetch incorporation time from April 10 to May 10. Average dry matter and organic-N produced by hairy vetch were 5.7 ton/ha and 248 kgN/ha, respectively. Corn growth and yield decreased as delayed corn planting time after May in spite of increasing dry matter and N-yield of hairy vetch. Nitrogen concentration of corn grain, stalk and whole plant at harvest were the highest in May 5 planting, but total N-uptake of May 5 planting were not different from that of April 25 planting because of lower grain yield. It was concluded that the proper incorporation time of hairy vetch and corn planting time were April 20 and April 25, respectively, because grain yield was the highest and corn could use hairy vetch-N effectively to produce dry matter.