• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.2
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• pp.349-355
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• 2004

The purpose of this study was to estimate effect of academic examination stress on taste perception and nutrient intakes in university students. Physical status, blood pressure, stress score using stress test of 2 types, recognition threshold and preference for taste, nutrient intakes using diet record method were measured before and after examination in 20 subjects. Mean age, height, weight, and BMI of the subjects were 23.39$\pm$1.20 years, 164.56$\pm$7.99 cm, 60.66$\pm$13.23 kg, 22.28$\pm$4.56 kg/$m^2$, respectively. Stress scores before examination of the subjects were significantly higher than those after examination. There were no significant differences in blood pressure, pulse rate, recognition threshold and just right concentration for sweetness and saltness, and food and nutrient intakes between pre- and post-examination. There were significantly positive correlation between stress score and diastolic blood pressure. And threshold concentration for saltness was positively correlated with threshold concentration for sweetness and animal protein intake. These results show no effect of examination stress on taste perception and nutrient intakes in university students. This may be due to low level of stress. Therefore, it is needed to study about effect of more higher level of stress on taste perception and nutrient intakes.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.9
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• pp.1091-1096
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• 2017

The aim of this study was the validation of a modified analytical method for determination of oxypaeoniflorin and paeoniflorin in Moutan Cortex Radicis extract. For validation of the analytical method, we modified established analytical methods and validated improvement. For validation, the specificity, linearity, precision, accuracy, limit of detection (LOD), and limit of quantification of oxypaeoniflorin and paeoniflorin were measured by high performance liquid chromatography. The results show that the correlation coefficients of the calibration curve for oxypaeoniflorin and paeoniflorin were 1.0000 and 0.9998, respectively. The LOD for oxypaeoniflorin and paeoniflorin were $0.23{\mu}g/mL$ and $0.25{\mu}g/mL$, respectively. The inter-day and intra-day precision values of oxypaeoniflorin and paeoniflorin were 0.70~3.19% and 1.74~2.43%, and 0.32~0.92% and 0.62~2.28%, respectively. The inter-day and intra-day accuracies of oxypaeoniflorin and paeoniflorin were 98.33~102.11% and 97.72~118.12%, and 98.44~101.56% and 97.10~112.00%, respectively. Therefore, the analytical method was validated for the detection of oxypaeoniflorin and paeoniflorin in Moutan Cortex Radicis.

• Journal of Bio-Environment Control
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• v.17 no.3
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• pp.231-237
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• 2008

Objective of this research was to investigate the effect of calcium concentrations in the fertilizer solution on growth and development of Ca deficiency in 'Maehyang' strawberry (Fragaria $\times$ ananassa Duch.). The margins of the youngest leaves were scorched and they developed a cupped shape as they were expanded in Ca deficient plants. The vein area of the youngest leaves became brown when the deficiency became severe. The quadratic responses were observed in dry weight production to elevated Ca concentrations in fertilizer solutions with the highest growth in 4.5 mM treatment. The regression equation was y=2.4026+1.0209x-$0.098x^2$ $(R^2=0.3546^{***})$. However, tissue Ca contents increased lineally as the Ca concentrations in fertilizer solutions were elevated (y=1.2108+0.1333x, $R^2=0.9189^{***}$). In changes of the fresh weight and Ca concentrations in petiole sap, fresh weight production showed quadratic responses to elevated Ca concentrations in fertilizer solution, but Ca concentration increased lineally. The equations in changes of fresh weight and Ca concentrations were y=9.273+4.882x-$0.4245x^2$ $(R^2=0.4935^{***})$ and y=52.311+3.2917x $(R^2=0.6918^{***})$, respectively. When the concentration of calcium at which plant growth was retarded by 10% is regarded as critical concentration level, the calcium contents based on dry weight of above ground plant tissue and in petiole sap should be in the range between 1.6 to 2.25% and 63 to $79mg{\cdot}kg^{-1}$, respectively.

• Horticultural Science & Technology
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• v.30 no.5
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• pp.477-483
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• 2012

This study was carried out to investigate the influence of copper concentrations in fertilizer solution on the growth of and nutrient uptake by domestically bred strawberries. The characterization of toxicity symptoms as well as tissue analyses based on dry weight of above ground tissue were also conducted to determine the threshold levels in plants when toxicity developed in copper. The dry weights of the above ground tissue were not significantly different among the treatments of 0.25 mM to 1.0 mM in 'Keumhyang' and 'Maehyang' strawberries and that of 0.25 mM to 3.0 mM in 'Seolhyang' strawberry. This indicates that the 'Seolhyang' strawberry is more tolerant to copper toxicity than 'Keumhyang' or 'Maehyang' strawberries. Application of copper at high concentrations resulted in severe toxicity such as death of extensive areas of leaves. The lower leaves became yellow and die rapidly as the symptoms spread up the plants. The leaf blades and petioles died back to the crown and hang on by mechanical attachment. Symptoms of copper toxicity in lower leaves developed as browning on leaf margins and in patches between leaf veins that became necrotic. The elevation of copper concentrations in fertilizer solution did not influence the tissue phosphorus, potassium, calcium, and magnesium contents based on the dry weight of the above ground tissue. The tissue copper contents increased lineally as the copper concentrations in fertilizer solution were elevated. But the tissue iron, manganese and boron contents were not influenced by the concentrations. When the concentration of copper at which growth of a plant is retarded by 10% is regarded as threshold level, the copper contents based on dry weight of above ground plant tissue should be lower than 71.4, 57.9 and 74.8 $mg{\cdot}kg^{-1}$ in 'Keumhyang', 'Maehyang' and 'Seolhyang' strawberries, respectively. The symptom characterization and established threshold level in copper toxicity would help growers to prevent the reduction of crop growth and yield in 'Seolhyang' strawberry cultivation.

• Korean Journal of Environmental Agriculture
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• v.16 no.2
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• pp.136-141
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• 1997

In this study, we can be obtained the following conclusions about the characteristics of leachate with passed time in the expired landfill. Compared with the expired landfilling H. and S., pH shows a tendency to increase in E., because $NH_3$ is created by anaerobic degradation and dissolved in leachate. The initial BOD and COD of E. and S. are high in similar concentration but H. is low, Since the organics of waste in H. are lower than in E. and S. during landfilling. SS of E. in concentration is increased and very altered, because food of combustible in E. is higher than it in H. and S.. According to passed time, T-N is high in concentration but T-P shows a similar tendency. Heavy metals of leachate is lower than threshold concentrations. If leachate is treated biologically, microbes are not inibitory.

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.365-371
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• 2007

Objective of this research was to investigate the effect of nitrogen concentrations in the fertilizer solution on growth and development of nutrient deficiency in leaf perilla (Perilla frutesens). The nutrient concentrations in above-ground plant tissue, petiole sap and soil solution of root media were also determined. Nitrogen deficiency resulted in dwarfed growth, small leaves, and bright yellow color of older leaves. The leaves of deficient plants became uniform yellowing in color and finally necrosis occurred on the deficient leaves. Elevation of N concentrations in the fertigation solution from 0 to 20 mM increased the crop growth in leaf length and width as well as fresh and dry weights of above ground plant tissue. That also resulted in the increase of chlorophyll contents. However, light toxicity symptoms such as abnormal leaf surface appeared on crops grown in 20 mM N fertilization. The plant growth was commercially acceptable in the treatments of 10 and 15 mM N. The plants with acceptable growth had 0.9 to 1.25% in N contents of above-ground plant tissue, 800 to $3,300mg{\cdot}kg^{-1}$ in the $NO_3-N$ concentrations of petiole sap, and 28.7 to $47.3mg{\cdot}kg^{-1}$ in the $NO_3-N$ concentrations of soil solution (1:2 extract) at 75 days after transplanting.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.3
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• pp.85-93
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• 1991

To investigate the effect of the initial sediment concentration ($C_o$) and bed shear stress (${\tau}_b$) on the settling properties of silty mud, deposition experiments were conducted in a recirculating flume using silty mud sediment taken from the Youngkwang coast which is located in the eastern Yellow Sea. The relative concentration, $C/C_o$ (C=depth averaged concentration), and the relative equilibrium concentration, $C_{eq}/C_o$ ($C_{eq}$=depth averaged concentration in the equilibrium state), have been found to depend much more strongly on the bed shear stress than initial concentration, and to increase with increasing bed shear stress. The minimum value. ${\tau}_{bmin}$, and maximum value. ${\tau}_{bmax}$, of critical bed shear stress for deposition of the Youngkwang sediment were deduced to be $0.017N/m^2$ and $1.25N/m^2$, respectively, and these values depend strongly on the properties of sediment (grain size and mineralogy). Formulas for the relative concentration and apparent median settling velocity in the range of ${\tau}_b{\geq}{\tau}_{bmin}$ were deduced. The apparent median settling velocity was found to depend much more strongly on the bed shear stress than the initial concentration and to decrease exponentially with increasing bed shear stress.

• Korean Journal of Food Science and Technology
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• v.15 no.4
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• pp.342-347
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• 1983

The effects of barley tea concentration and atomizing air pressure on the size, homogeneity and distribution of the sprayed droplets were investigated. An equation relating mean diameter (${\overline{D}}$) with the concentration where the coefficient a and b were determined empirically. As the operating air pressure was increased, the mean diameter of the droplets decreased and finally reached the limiting mean diameter, $36{\mu}m$ at 15.7% barley tea concentration. The homogeneity of the droplets increased with the operating air pressure, increase and it was decreased steadily as the soluble solid concentration increased up to 20% and markedly over 20% at every operating air pressure. The distribution ($P_D$) of sprayed droplets related with the droplet size as the following exponential equation; $P_D$ = e 1nD + f where e and f are empirical constants.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.10a
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• pp.170-175
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• 2003

화학과 석유화학 산업의 많은 공정에서는 가연성가스가 공정 가스로 사용되거나 발생될 수도 있다. 최근 석유화학단지에서 화재 및 폭발이 빈번하게 발생되고 있으므로 이에 대한 재해를 예방하기 위해서는 공정 조건에서의 이들 가연성가스의 연소특성을 알 필요가 있다. 연소특성들로는 폭발한계, 인화점, 최소자연발화점, 최소산소농도, 최소발화에너지, 연소열 등을 들 수 있다.(중략)

• Environmental engineer
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• s.171
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• pp.46-51
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• 2000

한강, 낙동강등 주요수계의 수질을 개선하기 위해 정부는 일련의 특별법 제정을 통해 수질오염 총량관리제를 도입하여 시행할 예정이다. 총량관리제는 기존의 사후처리 및 농도규제에 근거한 수질관리의 한계를 극복하고 실질적인 수질개선을 달성할 수 있다는 점에서 일본 및 미국에서는 이미 오래 전부터 시행해오고 있다. 한강, 낙동강 수계의 총량관리 시행체제는 이러한 외국사례를 참고하고 해당지역 정서와 사회경제적인 여건 등의 지역특수성을 반영하여 개발되었다. 즉, 한