• Journal of Ginseng Research
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• v.27 no.3
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• pp.135-140
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• 2003

North American ginseng (Panax quinquefolius L.) was analysed for total ginsenosides and ten major ginsenosides (R$_{0}$ , Rb$_1$, Rb$_2$, Rc, Rd, Re, Rf, Rg$_1$, pseudoginsenoside F$_{11}$ and gypenoside XVII), and variations in ginsenoside content with age of plant (over a four-year-period) and geographic location (Ontario versus British Columbia) were investigated. In the roots the total ginsenoside content increased with age up to 58-100 mgㆍg$^{-1}$ dry weights in the fourth year, but in leaves it remained constant over time. Roots and leaves, moreover, had different proportions of individual ginsenosides. The most abundant ginsenosides were Rb$_1$ (56mgㆍg$^{-1}$ for Ontario; 37mgㆍg$^{-1}$ for British Columbia) and Re (21mgㆍg$^{-1}$ for Ontario; 15 mgㆍg$^{-1}$ for British Columbia) in roots, and Rd (28-38 mgㆍg$^{-1}$ ), Re (20-25 mgㆍg$^{-1}$ ), and Rb$_2$ (13-19 mgㆍg$^{-1}$ ) in leaves. Measurable quantities of Rf were found in leaves (0.4-1.8 mgㆍg$^{-1}$ ) but not in roots or stems. Our results show that ginsenoside profiles in general, and Rf in particular, could be used for chemical fingerprinting to distinguish the different parts of the ginseng plant, and that ginseng leaves could be valuable sources of the ginsenosides Rd, Re, and Rb$_2$.

• Journal of the Korean earth science society
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• v.21 no.1
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• pp.81-92
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• 2000

The purpose of this study is to elucidate the characteristic of this study is of attitudinal variation of water quality for nine representative springs in the Halla mountain region. The evolutional processes of the spring water also have been studied. Results of hydrogeochemical analyses show that Gwaneumsa spring is very high in pH. The spring waters from Yungsil, Namguksunwon, Sungpanark Oremok and Gwaneumsa which springs situated lower than 1000m in altitude are relatively high concentrations in chloride, sulphate, nitrate nitrogen and sodium ions, indicating that they are affected by surrounding pollution sources. The concentrations of bicarbonate, sulphate and hydrogen ions in spring waters increase when the precipitation increases, whereas the concentrations of nitrate nitrogen, chloride and calcium ions decrease with increasing amounts of precipitation. The magnesium, sodium and electrical conductivity are nearly independent of the precipitation. The spring waters in the Halla mountain region belong to the groups of sodium or potassium type and bicarbonate type, except the Baegrogdam and Wiseorm spring water.

• Ocean Science Journal
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• v.41 no.3
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• pp.125-137
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• 2006

Nutrients, chlorophyll-a, particulate organic carbon (POC), and environmental conditions were extensively investigated in the northern East China Sea (ECS) near Cheju Island during three seasonal cruises from 2003 to 2005. In spring and autumn, relatively high concentrations of nitrate ($2.6{\sim}12.4\;{\mu}mol\;kg^{-1}$) and phosphate ($0.17{\sim}0.61\;{\mu}mol\;kg^{-1}$) were observed in the surface waters in the western part of the study area because of the large supply of nutrients from deep waters by vertical mixing. The surface concentrations of nitrate and phosphate in summer were much lower than those in spring and autumn, which is ascribed to a reduced nutrient supply from the deep waters in summer because of surface layer stratification. While previous studies indicate that upwellings of the Kuroshio Current and the Changjiang (Yangtze River) are main sources of nutrients in the ECS, these two inputs seem not to have contributed significantly to the build-up of nutrients in the northern ECS during the time of this study. The lower nitrate:phosphate (N:P) ratio in the surface waters and the positive correlation between the surface N:P ratio and nitrate concentration indicate that nitrate acts as a main nutrient limiting phytoplankton growth in the northern ECS, contrary to previous reports of phosphate-limited phytoplankton growth in the ECS. This difference arises because most surface water nutrients are supplied by vertical mixing from deep waters with low N:P ratios and are not directly influenced by the Changjiang, which has a high N:P ratio. Surface chlorophyll-a levels showed large seasonal variation, with high concentrations ($0.38{\sim}4.14\;mg\;m^{-3}$) in spring and autumn and low concentrations ($0.22{\sim}1.05\;mg\;m^{-3}$) in summer. The surface distribution of chlorophyll-a coincided fairly well with that of nitrate in the northern ECS, implying that nitrate is an important nutrient controlling phytoplankton biomass. The POC:chlorophyll-a ratio was $4{\sim}6$ times higher in summer than in spring and autumn, presumably because of the high summer phytoplankton death rate caused by nutrient depletion in the surface waters.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.3
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• pp.237-246
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• 2000

An experimental study has been carried out using a rotating water channel in order to investigate the effect of surface roughness on the vertical dispersion of plume within boundary layer. Dispersion measurements of tracers released from two sources with different height at neutral conditions over various rough terrain ranging from rural to urban have been performed. Various values of roughness length were simulated by combining of 4 stream velocities and 3 roughness element conditions. Dispersion measurements have also been made for rough terrain where high buildings are locally concentrated. Values of $\sigma$z increase with roughness and this tendency appears to apply both cases of with and without locally concentrated high buildings. The comparisons of the Bowne's nomogram on $\sigma$2 vs x relationship and the measurements of $\sigma$2 with roughness show good accordance in $\sigma$2 distribution at stability D class over rural, suburban and urban terrain. For constant roughness length the $\sigma$2 values of plumes from lower source height are smaller than those of plumes from higher source at short downwind distance, but this relationship becomes reverse as distance increases. Crossing appears to be made before about 2km. The value of constant I in McMullen's equation $\sigma$2=exp [I+J(In x) + K(In x)2] appears to increase with roughness length, however, the relationships between other constants and roughness have been confirmed. The values of $\sigma$2 for various downwind distances, estimated by using an equation which is employed in ISC (Industrial Source Complex) dispersion model for areas where high buildings are locally assembled, are in accordance with measurements from water channel experiments.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.1
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• pp.63-71
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• 2006

An automated carbonyl measurement system was constructed. Atmospheric carbonyl compounds were extracted onto DNPH containing collection solution while flowing through a glass coil. Each carbonyl species was separated on a HPLC column and quantified by UV absorption detector. Using this system, carbonyl compounds were continuously measured at the campus of Korea University in Seoul, Korea during June, 2005. Sampling resolution was 30 minutes and the detection limit of HCHO was 0.19 ppbv. Also, $\O_{3}$, it's precursors, and meteorological parameters were measured. The maximum, minimum, average, and median concentrations of HCHO during the whole experiment was 35.8 ppbv, 1.4 ppbv, 11.7 ppbv, and 9.3 ppbv respectively. Formaldehyde showed a distinct diurnal variation with a broad maximum around 13 $\sim$ 15, which was 1 $\sim$ 3 hours ahead of an ozone maximum. During a couple of days, however, HCHO concentrations were kept high through the night or increased concomitantly with NOx in the morning. These results imply that HCHO was mainly produced from the photochemical oxidation of VOCs, but local emission sources couldn't be ruled out. The differences between daily maximum and minimum of $O_{3}$ and HCHO were calculated for 11 days of June, when typical diurnal variations were observed for the two species. A strong positive correlation was found between $\Delta O_{3}$ and $\Delta HCHO$ and the average mole ratio of $\Delta HCHO$ to $\Delta O_{3}$ was 2.6. It indicates that formaldehyde played a key role in $\Delta O_{3}$ production as an indicator species in Metropolitan Seoul during June, 2005.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.197-201
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• 1983

Underwater ambient noise level was measured at two points near the Youngil Bay. The environmental characteristics depend upon oceanographic conditions of sound propagation ana its implication on the source of ambient noise. Some noise sources were estimated, and the effect of the oceanographic conditions on the noise level variation had been considered. The results were as follows : 1) At the nearshore station of Youngil Bay, the ambient noise level in the near bottom(45m) was lower than that of the near surface(10m) by 15dB. This difference was due to spherical spreading from the upper to the lower layer. 2) At the open sea station which is located outside of the thermal front existing near the Youngil Bay, the ambient noise level of the upper layer(20m) was higher than that of the lower layer (100m) by $8{\sim}12dB$ below 50Hz and $15{\sim}23dB$ above 50Hz. 3) Above 60Hz the ambient noise level at the nearshore station was higher than that of the open sea station, while below 60Hz, the result was reverse. It appears that a boundary layer existed between the two stations.

• Fisheries and Aquatic Sciences
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• v.11 no.2
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• pp.82-87
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• 2008

Marine fisheries are important natural resources and must be maintained, especially fish species that are important sources of food. Despite the increase in stocking programs to maintain fisheries with artificially raised fish, the genetic impact stocking has on the wild fry population has not been addressed. Genetic variation in rock bream, Oplegnathus fasciatus, within and between wild-caught parents and the $F_1$ generation produced by them in 1 day was assayed using nine highly variable micro satellite markers. The nine micro satellite loci used in this study displayed diverse polymorphisms, and in total, 98 different alleles were observed over all loci. Differences in genetic variability of the $F_1$ offspring compared to their wild-caught parents (brood stock) were observed in terms of allele frequency, gene diversity, and heterozygosity. Although the $F_1$ generation of rock bream was missing 16% of the micro satellite alleles, no significant reduction was found in mean heterozygosity of the $F_1$ population compared to the brood stock. Eight of nine loci showed significant Hardy-Weinberg equilibrium (HWE) deviations in the $F_1$ population, while the brood stock deviated from HWE at three micro satellite loci (KOF85, KOF360 and KOF374). These deviations showed mostly a deficit of heterozygotes. Our results provide evidence for genetic differences in the $F_1$ hatchery offspring compared to their wild-caught parents and reinforce the need for a series of consecutive egg collections to avoid the loss of genetic variability. This also further underscores the importance of monitoring genetic variability of hatchery populations for the conservation of natural rock bream resources.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.19-26
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• 2020

Small nuclear reactor features higher power capacity, longer operation life than conventional power sources. It could be an ideal alternative of existing power source applied for special equipment for terrestrial or underwater missions. In this paper, a 25kWe heat pipe cooled reactor power source applied for multiple use is preliminary designed. Based on the design, a thermal-hydraulic analysis code for heat pipe cooled reactor is developed to analyze steady and transient performance of the designed nuclear reactor. For reactor design, UN fuel with 65% enrichment and potassium heat pipes are adopted in the reactor core. Tungsten and LiH are adopted as radiation shield on both sides of the reactor core. The reactor is controlled by 6 control drums with B₄C neutron absorbers. Thermoelectric generator (TEG) converts fission heat into electricity. Cooling water removes waste heat out of the reactor. The thermal-hydraulic characteristics of heat pipes are simulated using thermal resistance network method. Thermal parameters of steady and transient conditions, such as the temperature distribution of every key components are obtained. Then the postulated reactor accidents for heat pipe cooled reactor, including power variation, single heat pipe failure and cooling channel blockage, are analyzed and evaluated. Results show that all the designed parameters satisfy the safety requirements. This work could provide reference to the design and application of the heat pipe cooled nuclear power source.

• Health Policy and Management
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• v.33 no.1
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• pp.40-54
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• 2023

Background: Based on the increase in the needs for convalescent rehabilitation medical services in Korea, this study aims to calculate the needs for rehabilitation services and examine its determinants for 229 regions. Methods: Claim data from the Health Insurance Review and Assessment Service were used to estimate patients who need to receive rehabilitation services, and data from various sources were also used for analysis. The number of cases and incidence rates of hospitalization related to convalescent rehabilitation were calculated to estimate the needs for services by region, and the results were visualized via a map. Multivariate regression and fixed effects regression using panel data were performed to identify the determinants of regional variation of the incidence rate. Results: First, the incidence rate of rural areas such as Jeolla-do, Gyeongsang-do, and Chungcheong-do was higher than urban areas (metropolitan cities). Second, the population, proportion of the elder, medical aid recipients, financial independence, traffic deaths, smoking, diabetes rate, and medical infrastructure correlated significantly with the incidence rate. Third, 'rho' values which mean the fraction of variance due to individual terms in panel data regression models were 0.965 and 0.976, respectively. Conclusion: The incidence rate of hospitalizations was correlated with most independent variables in this study and there is a gap between urban and rural areas. These regional disparities are fixed in our society. An improved regional convalescent rehabilitation system is suggested to cover the entire area including rural areas with a high rate of aging.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.8
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• pp.1105-1116
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• 2017

Objective: A meta-analysis was conducted to evaluate the effects of supplemental fat containing saturated free fatty acids (FA) on milk performance of Holstein dairy cows. Methods: A database was developed from 21 studies published between 1991 and 2016 that included 502 dairy cows and a total of 29 to 30 comparisons between dietary treatment and control without fat supplementation. Only saturated free FA (>80% of total FA) was considered as the supplemental fat. Concentration of the supplemental fat was not higher than 3.5% of diet dry matter (DM). Dairy cows were offered total mixed ration, and fed individually. Statistical analysis was conducted using random- or mixed-effects models with Metafor package in R. Results: Sub-group analysis showed that there were no differences in studies between randomized block design and Latin square/crossover design for dry matter intake (DMI) and milk production responses to the supplemental fat (all response variables, $p{\geq}0.344$). The supplemental fat across all studies improved milk yield, milk fat concentration and yield, and milk protein yield by 1.684 kg/d (p<0.001), 0.095 percent unit (p = 0.003), 0.072 kg/d (p<0.001), and 0.036 kg/d (p<0.001), respectively, but tended to decrease milk protein concentration (mean difference = -0.022 percent unit; p = 0.063) while DMI (mean difference = 0.061 kg/d; p = 0.768) remained unchanged. The assessment of heterogeneity suggested that no substantial heterogeneity occurred among all studies for DMI and milk production responses to the supplemental fat (all response variables, $I^2{\leq}24.1%$; $p{\geq}0.166$). Conclusion: The effects of saturated free FA were quantitatively evaluated. Higher milk production and yields of milk fat and protein, with DMI remaining unchanged, indicated that saturated free FA, supplemented at ${\leq}3.5%$ dietary DM from commercially available fat sources, likely improved the efficiency of milk production. Nevertheless, more studies are needed to assess the variation of production responses to different saturated free FA, either C16:0 or C18:0 alone, or in combination with potentially optimal ratio, when supplemented in dairy cow diets.