• 태양에너지
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• 제20권2호
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• pp.31-42
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• 2000

Since the direct normal insolation is a main factor for designing any focusing solar system, it is necessary to evaluate its characteristics all over the country. We have begun collecting direct normal insolation data since December 1990 at 16 different locations and considerable effort has been made for constructing a standard value from measured data at each station. KIER(Korea Institute of Energy Research)'s new data will be extensively used by concentrating system users or designers as well as by research institutes. From the results, we can conclude that 1) Yearly mean $4,576kcal/m^2.day$ of the direct normal insolation was evaluated for clear day all over 16 areas in Korea. 2) Clear day's direct normal insolation of spring and summer were $4,710kcal/m^2.day$ and $4,960kcal/m^2.day$, and for fall and winter their values were $4,484kcal/m^2.day$ and $4,151kcal/m^2.day$ respectively. So, spring and summer were higher, and fall and winter were lower than the yearly mean value.

• 대한가정학회지
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• 제27권2호
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• pp.53-63
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• 1989

A untrition survey of early childhood was undertaken among 102 rural young children, aged 3 to 6, attending three day care centers of Hongcheon-gun, Kangwon province, in July of 1987, to investigate dietary and nutritional status. The results were obtained as follows: Mean values of height and arm circumference ranged from 96 to 97% of the KSRI's standards. However, mean value of weight met 91% of that standard. Mean value of hematocrit was 37.3±3.5%. According to the criterion established by the WHO, 3% of the subjects were proven to be anemic. Mean value of urinary urea nitrogen/creatinine ratio was 13.8±7.6; the higher the age lower the ratio was shown. Intake of energy and nutrients ranged from 63 to 88% of the RDAs. Carbohydrate provided 68% of total energy intake; protein accounted for 14%; fat provided 18%. Energy intake was divided among breakfast, lunch supper and snacks in a percentage ratio of 21:35:26:18. The survey clarified that the day care feeding largely supplemented the inadequate dietary intakes of these young children at home. Family factors, anthropometric measurements, biochemical results were positively correlated with nutrient intakes. Authors with this study can be contributed, as a reference, to develop the community nutrition programs as well as improving the quality of day care feeding.

• Geomechanics and Engineering
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• 제20권3호
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• pp.243-254
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• 2020

Due to the permanent damage to structures during earthquakes, soil liquefaction is an important issue in geotechnical earthquake engineering that needs to be investigated. Typical examples of soil liquefaction have been observed in many earthquakes, particularly in Alaska, Niigata (1964), San Fernando (1971), Loma Prieta (1989), Kobe (1995) and Izmit (1999) earthquakes. In this study, liquefaction behavior of uniform sands of different grain sizes was investigated by using the energy-based method. For this purpose, a total of 36 deformation-controlled tests were conducted on water-saturated samples in undrained conditions by using the cyclic simple shear test method and considering the relative density, effective stress and mean grain size parameters that affect the cumulative liquefaction energy. The results showed that as the mean grain size decreases, the liquefaction potential of the sand increases. In addition, with increasing effective stress and relative density, the resistance of sand against liquefaction decreases. Multiple regression analysis was performed on the test results and separate correlations were proposed for the samples with mean grain size of 0.11-0.26 mm and for the ones with 0.45-0.85 mm. The recommended relationships were compared to the ones existing in the literature and compatible results were obtained.

• Journal of Radiation Protection and Research
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• 제28권4호
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• pp.327-335
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• 2003

The commercially available neutron survey meter, the REM500, which uses a tissue equivalent proportional counter (TEPC) and the self-constructed TEPC were used to determine the microdosimetric quantities of several neutron calibration fields at Korea Atomic Energy Research Institute (KAERI). Microdosimetric spectra, absorbed dose, dose equivalent as well as quality factor were derived and compared with several neutron fields which were produced by using the shadow objects to make neutron scattered and being used as a kind of realistic neutron calibration fields at KAERI. The response of REM500 as a function of mean energy was evaluated with these neutron fields using the counts measured and the predetermined reference value. The response of the self-made TEPC and the REM500 was compared using one of the neutron calibration filelds of a $^{252}Cf$ source. The reference quantities of scattered neutron calibration fields were determined using a Bonner Sphere (BS). The value of frequency-mean lineal energy, dose-mean lineal energy and quality factor of two $^{252}Cf$ sources (unmoderated and $D_2O$ moderated) were determined to check the differences in the reference neutron fields between KAERI and Pacific Northwest National Laboratory (PNNL, USA) and the results were in good agreement within 1%. It means that there is no big difference in dosimetric quantifies of neutron calibration fields of two laboratories.

• Journal of Biosystems Engineering
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• 제25권1호
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• pp.39-46
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• 2000

This work was conducted to study the operating characteristics of a grinding system designed to obtain fine rice husk ash powder. To find better utilizing of rice husk, a valuable by-product from rice production, once the rice husk was incinerated and the thermal energy was recovered from the furnace, the ash was fed and pulverized in the grinding system resulting a fine powder to be used as a supplementary adding material to the portland cement manufacturing . The rice husk ash grinding system consisted of a high speed centrifugal fan for the preliminary coarse milling and a dry-type stirred ball mill for the subsequent fine grinding . Total grinding time 9 5, 15, 30, 45 min), impeller speed (250, 500, 750 rpm) , and mixed ratio (4.8, 7.9, 14.9) were three operating factors examined for the performance of a stirred ball mill used for the fine grinding of ash. With the stirred ball mill used in this study, the minimum attianable mean diameter of rice husk ash powder appeared to be 2 ${\mu}{\textrm}{m}$. During the find grinding, the difference in specific surface area of powder showed an increase and the grinding energy efficiency decreased with the increase in total grinding time, impeller speed ,and mixed ratio. For the operating conditions employed , the resulting mean diameter of fine ash powder, specific energy input, and grinding energy efficiency were in the range of 1.79 --16.04${\mu}{\textrm}{m}$, 0.072-5.226kWh/kg, an d1.11-12.15$m^2$/Wh, respectively. Grinding time of 30 min , impeller speed of 750 rpm, and mixed ratio of 4.8 were chosen as the best operating conditions of the stirred ball mill for fine grinding . At these conditions, mean particle diameter of the fine ash, grinding energy efficiency, grinding throughtput, and specific energy input were 2.73${\mu}{\textrm}{m}$, 3.95$m^2$/Wh, 0.25kg/h, and 1.22kWh/kg, respectively.

• 한국태양에너지학회 논문집
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• 제36권1호
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• pp.11-18
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• 2016

The local wind systems in the Pohang region were categorized into wind sectors. Still, thorough knowledge of wind resource assessment, wind environment analysis, and atmospheric environmental impact assessment was required since the region has outstanding wind resources, it is located on the path of typhoon, and it has large-scale atmospheric pollution sources. To overcome the resolution limitation of meteorological dataset and problems of categorization criteria of the preceding studies, the high-resolution wind resource map of the Korea Institute of Energy Research was used as time-series meteorological data; the 2-step method of determining the clustering coefficient through hierarchical clustering analysis and subsequently categorizing the wind sectors through non-hierarchical K-means clustering analysis was adopted. The similarity of normalized time-series wind vector was proposed as the Euclidean distance. The meteor-statistical characteristics of the mean vector wind distribution and meteorological variables of each wind sector were compared. The comparison confirmed significant differences among wind sectors according to the terrain elevation, mean wind speed, Weibull shape parameter, etc.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.911-916
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• 2012

Ion selectivity in a simple cyclic peptide nanotube, composed of four cyclo[-(D-Ala-Glu-D-Ala-Gln)$_2-$] units, is investigated by calculating the PMF profiles of $Na^+$, $K^+$, and $Cl^-$ ions permeating through the peptide nanotube in water. The final PMF profiles of the ions obtained from the umbrella sampling (US) method show an excellent agreement with those from the thermodynamic integration (TI) method. The PMF profiles of $Na^+$ and $K^+$ display free energy wells while the PMF curve of $Cl^-$ features free energy barriers, indicating the selectivity of the cyclic peptide nanotube to cations. Decomposition of the total mean force into the contribution from each component in the system is also accomplished by using the TI method. The mean force decomposition profiles of $Na^+$ and $K^+$ demonstrate that the dehydration free energy barriers by water molecules near the channel entrance and inside the channel are completely compensated for by attractive electrostatic interactions between the cations and carbonyl oxygens in the nanotube. In the case of $Cl^-$, the dehydration free energy barriers are not eliminated by an interaction between the anion and the peptide nanotube, leading to the high free energy barriers in the PMF profile. Calculations of the coordination numbers of the ions with oxygen atoms pertaining to either water molecules or carbonyl groups in the peptide nanotube reveal that the stabilization of the cations in the midplane regions of the nanotube arises from the favorable interaction of the cations with the negatively charged carbonyl oxygens.

• 대한지역사회영양학회지
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• 제4권2호
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• pp.123-131
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• 1999

The nutritional status of 125 preschool children(Female : 56, Male : 69) residing in low income area of Seoul was surveyed. The mean family size was 4.3 and the mean monthly income was 921,000 won which was below the poverty level. Average heights of boys aged 3, 4, 5 and 6 were 98.6cm, 106.1cm, 111.9cm and 116.0cm and those for girls were 99.4cm, 106.4cm, 110.9cm, and 116.0cm, respectively. There was no significant difference between the height of boys and girls. The proportion of children showing stunted growth(<90% of Korean standard of height) was 3.2%. The mean weight of boys for each age group(3, 4, 5, 6) were not significantly differient from that of girls. The proportion of children assessed as moderately underweight (<80-90% of Korean Standard of weight) was 10.4% and 3.2% of children was underweight(<80% of weight standard). The group of children aged 3 were taking adequate energy, whereas the mean energy intake of children aged 4.5 and 6 were within 77.3-78.6% of RDA. The proportion of energy derived from carbohydrate, fat and protein was 60.1%, 24.6% and 15.3%. The high proportion of energy derived from fat seems partly due to high energy intake from fat in the snack. The nutrients which did not meet 75% of the RDA were vitamin A and calcium for children aged 5, and iron for children aged 3 to 5. Carbohydrate intake was positively correlated with the height, weight and girth of chest(P<0.05-P<0.001). There was positive correlation between protein intake and weight, girth of chest and BMI, respectively(P<0.05). Iron intake showed positive relationship with height, weight and BMI(P<0.05).

• 대한지역사회영양학회지
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• 제1권1호
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• pp.47-60
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• 1996

This study was carried out to investigate growth performance, energy and protein metabolism of breast and formula fed infants from birth to 3 months postpartum. There were four groups : breast fed(BF) and three formula fed groups(FFM, FFN and FFP). There was no significant difference in the height of infants according to feeding method and formula brands. However, mean weight of FFM was significantly higher than that of FFP and BF at 1 and 3 months postpartum, respectively. Mean head circumference of FFN was lowest among groups. The average intake of breast milk was $781.4{\;}{pm}{\;}119.3m{\ell}/day$ and that of formula was $848.6{\;}{pm}{\;}118.5m{\ell}/day$. Mean apparent digestible energy intakes of formula-fed infants and breast-fed infants during 3months were 568.9 $\pm$146.9 kca1/day and 657.9$\pm$212.8 kca1/day, respectively. The average protein intake of brest-fed and formula-fed infants were 8.3$\pm$1.6g/day and 14.1$\pm$14.1 g/day, respectively. The protein intakes of formula-fed infants were significantly higher than those of breast-fed infants at 1, 2, 3 months. The apparent protein digestibility of breast-fed infants was singnificantly higher compared to formula fed infant. These data suggest that RDA for infants be established and breast feeding be encouraged.

• Journal of Nutrition and Health
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• 제30권3호
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• pp.277-285
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• 1997

The purpose of this study was to investigate the relationship among nutrient intake, life style, and serum lipids level in 108 healthy middle-aged men in Taegu. A convenient method was to assess nutritional intake. Anthropometric measuement of body weight and hight were measured and average energy expenditure was calculated. The mean body mass index(BMI) was 22.8$\pm$2.4 and it was in the middle of the mean BMI of Korean men. Obesity rate of study subject were 13.2%. Daily energy intake was not sufficient as 88.4% of recommended dietary allowances and the energy percentage of carboydrate, fat protein was 65 : 21 : 14. Mean intake of vitamin A, B1, C and Ca were lower than RDA. There was a highly significant negative correlation between the systolic blood pressure and calcium intake(r=-0.28, p<0.05). Smokers showed significantly higher blood glucose than non-smokers. Skipping meals and uneven diurnal distribution(no breakfast and large evening meals) are associated with high triglyceride level in this population. There was a highly significant correlation between body weight and plasma lipids. Energy expenditure was negatively correlated with plasma triglyceride level. Especially, atherogenic index was significantly lower in job-time physically active worker than that in sedentary worker. Above data provides valuable imformation to the community for program planning as well as to health providers who work individual male adults to meet their nutrition needs and to control blood lipids.