• Journal of Mechanical Science and Technology
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• 제19권7호
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• pp.1393-1404
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• 2005

Fatigue crack growth and life have been estimated based on established empirical equations. In this paper, an alternative method using artificial neural network (ANN) -based model developed to predict fatigue damages simultaneously. To learn and generalize the ANN, fatigue crack growth rate and life data were built up using in-plane bending fatigue test results. Single fracture mechanical parameter or nondestructive parameter can't predict fatigue damage accurately but multiple fracture mechanical parameters or nondestructive parameters can. Existing fatigue damage modeling used this merit but limited real-time damage monitoring. Therefore, this study shows fatigue damage model using backpropagation neural networks on the basis of X -ray half breadth ratio B / $B_o$, fractal dimension $D_f$ and fracture mechanical parameters can estimate fatigue crack growth rate da/ dN and cycle ratio N / $N_f$ at the same time within engineering limit error ($5\%$).

• The Journal of Asian Finance, Economics and Business
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• 제9권6호
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• pp.297-302
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• 2022

The current study examines the relationship between inventory management efficiency and financial performance in Saudi Arabian companies. The study collected data from the companies listed on Tadawul (a Saudi Arabian stock exchange) during the period starting from 2016 and ending in 2020. The study uses pooled regression model by incorporating Return on Assets (ROA) and Inventory Turnover Ratio (ITR) as a performance measurement variable and inventory conversion period as an inventory management variable to report the results. The results show a positive and significant association between inventory management and firms' financial growth measured in terms of Return on Assets (ROA). Further, the study reports a positive and significant association between the inventory conversion period and inventory turnover (ITR). This shows that managing inventory efficiently shall positively impact the firm's performance. The other variables, such as debt ratio and gross profit, are positively related to ROA and negatively correlated with ITR. The firm growth is positively associated with both the dependent variables. The results suggest that the management of inventory in Saudi Arabian firms is efficient. Further, the firm size is positively associated with ROA and ITR. This shows a nexus between inventory management efficiency and firms' financial growth in Saudi Arabian companies.

• 수산해양교육연구
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• 제24권2호
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• pp.203-209
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• 2012

We investigated the effect on dietary EPA (eicosapentaenoic acid) source (EP) into formulated diets for growth of brackish flea, Diaphanosoma celebensis. The highest density and specific growth rate (SGR) of brackish fleas were observed on Tetraselmis suecica (TE) trial, but these of trial were not significantly differed with that of Chlorella (CH) + Crypthecodinium sp. (CR) + EP trial, contained EPA oil (P>0.05). Contrastively, CH trial showed the lowest SGR. And in the RNA/DNA ratio, 0.08 of TE trial was the highest ratio out of whole trials, but the trial not significantly differed with that of CH + CR + EP trial (P>0.05). But, the ratio of CH trial was the lowest ratio at 0.05 out of whole trials (P<0.05). Through out results, the EPA source for flea culture was showed a positive effect through their growth and SGR. Therefore, we suggested that a usage of the source with CH could replace T. suecica as good diet for culture of the brackish flea.

• 한국해양공학회지
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• 제4권2호
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• pp.100-111
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• 1990

In this paper, fatigue tests were carried out at stress test levels of 461 MPa, 441 MPa, and 431 MPa by using smooth specimen of$2_{1/4}$ Cr-1 Mo steel with the stress ratio(R) of 0.05. The initiation, growth and coalescense process of the major cracks and sub-cracks among the fatigue cracks on the smooth specimen are investigated and measured under each stress level at a constant cycle ratio by the replica technique with optical microscope. Some of the important results are as follows: In spite of the difference of stress levels, the major crack data gather into a small band in the curve of surface crack length and crack depth against cycle ratio N/Nf. The sub-crack data, however, deviate from the band of the major crack. The growth rates, da/dN, of major and sub-crack plotted against the stress intensity factor range, ${\Delta}K$, have the tendency to be compressed on a relatively small band. But it is more effective to predict fatigue life through major cracks. The propagation behavior of surface microcracks on the smooth specimens coincides with that of the specimen having an artificial small surface defect or through crack.

• 한국약용작물학회지
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• 제21권3호
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• pp.174-178
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• 2013

Lime-bordeaux mixture has been used to prevent diseases in the field of ginseng. The purpose of this study is to investigate the efficacy of lime-bordeaux depending on the concentration and treatment time on major diseases of ginseng such as Alternaria blight and anthracnose, and to evaluate the root growth of ginseng. Lime-bordeaux caused damage on leaf when it was sprayed on ginseng between April and early May. No difference was found in root growth by spraying lime-bordeaux mixture between ratio 4-4 and 8-8 ratio in concentration. Plot of 6-6 raito and 8-8 ratio appeared to be similar efficacy compared to that of practical chemical control. However, the plot of 4-4 ratio showed lower than that of chemical control.

• 대한기계학회논문집
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• 제13권1호
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• pp.115-124
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• 1989

본 연구에서는 2상계 스테인리스강의 모재,용접재 및 용접후 열처리재 3종류의 경우에 대하여 피로크랙 전파특성을 피로크랙의 하한계치 근방에서 금속조직적인 영향을 검토하기 위하여, 각 조건에 대한 피로크랙 전파속도의 하한 계치를 구하였고 피로식검후의 파단면을 주사전자현미경(SEM)으로 관찰하였다. 용접재에 대하여는 용착부 부근 용접열영향부의 입경측정, .alpha./.gamma.상의 체적비교율의 변화량 측정 및 용접재와 용접후열처리재의 잔유응력분포측정을 통하여 피로크랙의 하한계특성에 미치는 여러가지 영향인자에 대하여 검토하였다.

• 수산해양교육연구
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• 제28권4호
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• pp.1098-1106
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• 2016

To study the influence of light intensity on blind-side hypermelanosis of starry flounder, Platichthys stellatus, we compared growth, glucose, cortisol, ratio of malpigmented blind-side area, ambicolored fish ratio and expression of mch mRNA for 60 days in 0 lux(darkness) and 20 lux(low light density). The test was done in duplicate at 50 fish/tank with the selected ordinary juvenile flounder. The rearing was performed in FRP aquarium tanks ($H100cm{\times}L100cm{\times}W100cm$). Growth was higher in the 0 lux. The ratio of malpigmented blind-side area and ambicolored fish ratio were significantly higher at the 0 lux than at the 20 lux. The result suggests that 20 lux could inhibit the hypermelanosis. The expression level of MCH 1, 2 mRNA was significantly lower in 0 lux, indicating that MCH 1, 2 and light intensity are related to blind-side hypermelanosis of starry flounder.

• 동의생리병리학회지
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• 제22권3호
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• pp.624-629
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• 2008

Effects of Kyungohkgo Ga Nokyong(Yongohkgo) on growth development and learning ability were investigated growth and intellectual impairment rat with insufficient nutrition diet. We divided male Sprague-Dawley rats into 4 groups. They were Normal group, Growth deficiency rat with insufficient nutrition diet group, Growth deficiency rat with 0.1% Yongohkgo group and 0.2% Yongohkgo group. They were administered for 5 weeks. We measured body weight, and morris water maze test in escape distance, escape time and escape speed, serum growth hormone, insulin-like growth factor and thyroid stimulating hormone, RBC, concentration of Hb and PCV ratio, total WBC and its composition, the values of GOT and GPT activities. The results are as follows that Yongohkgo 0.1%, 0.2% groups were showed significantly different than control groups in body weight and the counts of RBC. In the morris water maze test, in escape distance and escape time, in concentration of Hb and PCV ratio, 0.2% Yongohkgo group were significantly different than control groups. Serum growth hormone, insulin- like growth factor and thyroid stimulating hormone showed a tendency to increase in Yongohkgo groups. The counts of total WBC and its composition, GOT, GPT activities showed no significantly different in all treatment groups. These results suggested that Yongohkgo have an effect of promoting growth and learning ability of rats and might be effect to treat various kinds of growth and learning ability delay in children.

• 디지털융복합연구
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• 제14권10호
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• pp.107-117
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• 2016

본 연구는 유가증권시장의 제조업을 대상으로 재무정보의 효율성이 기업가치에 미치는 영향에 대해 정보가 반영되는 시기를 중심으로 검증하고자 하였다. 이를 위해 재무제표 공시를 기준으로 분석기간을 당해(t)년도, 재무제표 공시 전 90일, 차기년도(t+1)로 구분하였다. 실증분석에 사용된 재무변수는 수익성, 성장성, 안정성, 활동성 및 시장가치 비율이며 재무정보가 분석기간 동안의 주식수익률에 미치는 영향을 단계적 회귀분석(stepwise regression)을 이용해 검증하였다. 실증분석 결과, 성장성과 수익성에 관한 정보는 당기의 주식수익률에 반영되는데 비해 안정성과 활동성에 관한 정보는 차기의 주식수익률에 정보를 반영하고 있는 것으로 나타났다. 총자산증가율은 당기 및 차기의 주식수익률에 부(-)의 유의적인 영향을 주는 것으로 나타났으며, 이는 재무정보가 산출된 동기간에 정보가 반영될 뿐만 아니라 차기에도 지속적으로 정보를 반영하는 것으로 판단된다. 본 연구는 재무정보의 성격에 따라 기업가치에 반영되는 시기가 달라지는 것을 발견하였다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.120-126
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• 1997

This paper examines the crack growth behavior of 7075-T651 aluminum alloy under high-low block loading condition. The cantilever beam type specimen with a chevron notch is used in this study. The crack growth and closure are investgated by compliance method. The applied initial stress ratios are R=-0.5, R=0.0 and R=0.25 Crack length($\alpha$), effective stress intensity factor range(ΔKeff), ratio of effective stress intensity factor range(U) and crack growth rate(d$\alpha$/dN) etc. are inspected fracture mechanics estimate.