• Korean Journal of Ecology and Environment
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• v.33 no.1 s.89
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• pp.51-60
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• 2000

In order to understand the trend and assessment of water pollution, seasonal water quality was determined in the main river and the tributaries from midstream to downstream of the Kum River from March 1998 to June 1999. Among environmental factors, the variation of nitrogen, phosphorus and chlorophyll-a was distinctive on an aspect of increase and decrease relatively to others, and particularly the impact of inorganic N ${\cdot}$ P inflowing into the main river was observed to be more significant at the Kapchon, Mihochon and Soksongchon among the tributaries. Water quality was highly related to hydrologic factor, and it was more deteriorated when water discharge maintains for a long time below normal flow or relatively at low condition of minimum and drought flow. These phenomena were remarkablee from December to March of the next year. $NH_4$ and SRP were decreased dramatically flowing toward the lower part of the river and chl-a was increased exponentially. While, the variations of $NO_3$ and $BOD_5$ were regular from midstream to downstream and there was no significant difference between the stations. Limiting nutrient for Phytoplankton growth seemed to be P than N because the ratio of TN/TP or DIN/SRP was relatively high as 42 or 544 in the main river, respectively. The main river and tributaries were ranked to be third grade, based on the assessment of BOD as an indirect indicator of organics, but particularly Kapchon was ranked to be over fifth grade. In addition, the inflow of high N ${\cdot}$ P nutrients from tributaries including Kapchon and Mihochon seemed to be major factor of the development of water pollution of the Kum River. On the other hand, persistent bloom of phytoplankton in lower part of the river was observed. As a conclusion, management of water quality for main source of pollution is urgent.

• Korean Journal of Soil Science and Fertilizer
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• v.3 no.1
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• pp.35-41
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• 1970

The experiment was conducted at the salt concentration of 0.5% and 1% end of April, respectively, in low and high-salty and the non-salty areas of silt loam with the Nongkwang, rice variety. The factorial design with confounding blocks of 3 levels each of 10, 15 and 20 kg of N, 8, 12 and 16kg of phosphate and potash, respectively, per 10a was applied. 1. N applications increased by 1.5 and 2 times with the fixed amount of $P_2O_5$ and $K_2O$ (8kg/10a each) increased the proportion absorbed to the applications of N in both non salty and low-salty areas. It was observed that the absorption of Ca and Si was inhibited by either an increased treatment of N alone or combination with the other nutrients in the salty area. 2. In the non-salty area, an increased applications of standard amount of N, $P_2O_5$ and $K_2O$ respectively did not increased the yields. Doubling the application of $K_2O$ resulted in a decreased yield. 3. Applications of additional of 1.5 and 2 times the 10 kg of N per 10a increased the rice yields 12% and 21% respectively, in the low-salty area. An increased application of $P_2O_5$ and $K_2O$ failed to bring about an increased yield. 4. Increasing the application of N gave a significant increased in the yield of rice grain and 1.5 times of N applications were seemed profitable on the high-salty area. Although an increased applications $P_2O_5$ and $K_2O$ seemed to increase the yields of grain, no significant increase was observed. 5. An increased application of N increased the number of panicles up to 1.5 times the standard amount in the non-salty area, but no further increase resulted by doubling the application. The number of panicles was increased in proportion to the increased application of N in both low and high-salty areas. An increased application of $P_2O_5$ increase the number of panicles per unit area in each experimental plot while that of $K_2O$ had no effect but rather decreased the number. 6. The effect of an increased application of N decreased the weight of panicle in the non-salty area, but when the application was increased to 1.5 times or more an increased weight of panicle resulted in both salty areas. Doubling the application had approximately the same effect as 1.5 times the application. Increasing the applications of $P_2O_5$ and $K_2O$ had no effect on the panicle weight in the experimental plots. Increasing the applications of N, $P_2O_5$ and $K_2O$ did not effect the weight of 1,000 grains produced in the non-salty and salty areas. Increasing the application of N decreased the number of grains per panicle in the non-salty area but increased the number of grains per panicle in either salty areas. 7. The ratio of matured grains was highest in the low-salty area and the lowest in the high-salty area. An increased N applications decreased the ratio of matured grains in the non-salty area. No effect was observed in both low and high-salty areas. Increased the $P_2O_5$ and $K_2O$ application showed no effect on the ratio of matured grains in the experimental plots. 8. Increased applications of N, $P_2O_5$ and $K_2O$ was observed not to change the percentage of milling recovery in any experimental plots. Broken rice was increased equally by an increased application of N in the non-salty and salty areas but more remarkably so in the former. 9. Increased applications of N increased the straw production equally in the non-salty, low and high-salty areas. However, no increased production was observed from heavier applications of $P_2O_5$ and $K_2O$. Additional N applications reduced the rate of rough grain weight v.s. straw weight in the non-salty area but increased the ratios in both low and high-salty areas. Additional $P_2O_5$ and $K_2O$ had no effect with the ratio.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.2
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• pp.34-45
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• 2016

Global warming and climate change have been caused by combustion of fossil fuels. The greenhouse gases contributed to the rise of temperature between $0.6^{\circ}C$ and $0.9^{\circ}C$ over the past century. Presently, fossil fuels account for about 88% of the commercial energy sources used. In developing countries, fossil fuels are a very attractive energy source because they are available and relatively inexpensive. The environmental problems with fossil fuels have been aggravating stress from already existing factors including acid deposition, urban air pollution, and climate change. In order to control greenhouse gas emissions, particularly CO2, fossil fuels must be replaced by eco-friendly fuels such as biomass. The use of renewable energy sources is becoming increasingly necessary. The biomass resources are the most common form of renewable energy. The conversion of biomass into energy can be achieved in a number of ways. The most common form of converted biomass is pellet fuels as biofuels made from compressed organic matter or biomass. Pellets from lignocellulosic biomass has compared to conventional fuels with a relatively low bulk and energy density and a low degree of homogeneity. Thermal pretreatment technology like torrefaction is applied to improve fuel efficiency of lignocellulosic biomass, i.e., less moisture and oxygen in the product, preferrable grinding properties, storage properties, etc.. During torrefacton, lignocelluosic biomass such as palm kernell shell (PKS) and empty fruit bunch (EFB) was roasted under an oxygen-depleted enviroment at temperature between 200 and $300^{\circ}C$. Low degree of thermal treatment led to the removal of moisture and low molecular volatile matters with low O/C and H/C elemental ratios. The mechanical characteristics of torrefied biomass have also been altered to a brittle and partly hydrophobic materials. Unfortunately, it was much harder to form pellets from torrefied PKS and EFB due to thermal degradation of lignin as a natural binder during torrefaction compared to non-torrefied ones. For easy pelletization of biomass with torrefaction, pellets from PKS and EFB were manufactured before torrefaction, and thereafter they were torrefied at different temperature. Even after torrefaction of pellets from PKS and EFB, their appearance was well preserved with better fuel efficiency than non-torrefied ones. The physical properties of the torrefied pellets largely depended on the torrefaction condition such as reaction time and reaction temperature. Temperature over $250^{\circ}C$ during torrefaction gave a significant impact on the fuel properties of the pellets. In particular, torrefied EFB pellets displayed much faster development of the fuel properties than did torrefied PKS pellets. During torrefaction, extensive carbonization with the increase of fixed carbons, the behavior of thermal degradation of torrefied biomass became significantly different according to the increase of torrefaction temperature. In conclusion, pelletization of PKS and EFB before torrefaction made it much easier to proceed with torrefaction of pellets from PKS and EFB, leading to excellent eco-friendly fuels.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.28 no.4
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• pp.85-97
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• 2010

This study analyzed the distribution, structure and environmental condition of the vegetation of the Chionanthus retusus Lindly et Paxton community at the Wansanchielbong in the Jeonju city to offer basic data for sustainable conservation and ecological management system. And the results are as follows; 1. The average pH of soil at the community was pH 5.69 and it was slightly higher than the average of forest soil pH of Korea. But if the degree of pH will be down, it will be needed some more fertilization of Calcium. 2. The total average for contents of organism was 4.98%. And the nitrate - nitrogen content(mg/kg) of A, B, C, D quadrat was 20.29%, 28.87%, 7.65%, and 23.3% respectively. And there were good condition except quadrat C which was contaminated by amount of earth and sand. 3. The flora of the Chionanthus retusus Lindly et Paxton community was listed as 60 taxa; 37 families, 50 genera, 47 species, 10 varieties and 3 forms. The average appearance species of each Quadrat were A sector 30, B sector 26, C sector 19 and D 19 taxa respectively. 4. Surveyed woody plants in the community were as follows : Chionanthus retusus, Zelkova serrata, Quercus variabilis, Cornus walteri, Robinia pseudo-acacia and those were mixed status. And Chionanthus retusus, Zelkova serrata, Robinia pseudo-acacia, Albizzia julibrisin, Cudrania tricuspidata, Symplocos chinensis for. pilosa were mixed in mid layer trees. Herbaceous plants were founded such as Chionanthus retusus, Zelkova serrata, Robinia pseudo-acacia, Grewia parviflora, Rosa multiflora, Trachelospermum asiaticum was dominant with 35~64% in the ground cover, and Commelina communis, Calamagrostis arundinacea, Dryopteris bissetiana, Lilium lancifolium were founded also. 5. The importance values of Chionanthus retusus was 40.2% in the quadrat A1, 50.2% at quadrat A, 50.0% B1, 45.2% B2, 22.4% C1, 73.6% C2, 33.2% D1 and the total average of I.V. was 44.9%. 6. The average height of surveyed Chionanthus retusus was 5.7m and the average DBH was 12.4cm. The number of trees higher than 2m were 107 and the number of trees lower than 2m were 63. The total numbers of Chionanthus retusus were 170. 7. The age of surveyed Chionanthus retusus were analyzed 42 thru 87 years old and that of Zelkova serrata were 42, Quercus variabilis were 60, Quercus aliena were 48, Robinia pseudo-acacia were 40. 8. The number of trees with DBH 40 through 50cm were 6, and that of 30~39cm were 3, and that of 20~29cm were 16, so the total number that was over 20cm was 25. And there were 70 trees under 10cm of DBH and 63 seedlings. It will be very important data to conserve the habitat that the structure and environmental condition of the Chionanthus retusus Lindly et Paxton community at the Wansanchielbong was stable, and sustainable monitoring will be needed. Now that community is nurse forest of Jeonju City but more positive preservation plan will be needed and assigning monument of city or province also be necessary.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.17-32
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• 2002

The purpose of this study was to find the rational method to analyze golf swing with specific property of club shaft. Three subjects were filmed by two high speed digital cameras with 500 fps. The phase analyzed was downswing of each subject. The three-dimensional coordinates of the anatomical landmarks were obtained with motion analysis system Kwon3d 3.0 version and smoothed by lowpass digital filter with cutoff frequency 6Hz. From these data, kinematic and kinetic variables were calculated using Matlab(ver 5.0) The variables for this study were angular velocity and accelerations, which were calculated and following conclusions have been made : 1) Golf swing time of stiff club is faster than that of regular club. 2) In shoulder joint motion of swing with the stiff club, x-stiff showed mort rapid negative acceleration than that of regular club. 3) In regular club, the velocity of club head would be more effective velocity, which was increasing, than those of other clubs before impact. 4) In wrist joint motion of swing with stiff club, x-stiff club showed faster than regular club in the downswing and impact more rapid negative acceleration.

• KSBB Journal
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• v.14 no.3
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• pp.309-314
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• 1999

In order to produce high concentration of sodium gluconate, optimization of the fermentation conditions, such as glucose concentration, inoculum size, dissolved oxygen concentration and glucose feeding method, was examined. When the glucose concentration was maintained in the range of 30∼50 g/L during the batch fermentation, glucose conversion yield and productivity were 92.2% and 6.0 g/L/hr, respectively. In the case of the low concentration below 30 g/L, the yield decreased by about 25%. As the inoculum size increased above 20%(w/v), lag phase was shortened but the productivity decreased. The dissolved oxygen level of 60∼70% was shown to be the threshold point for 75% of increase in the productivity of sodium gluconate. Finally, optimal glucose feeding rate was determined using various feeding methods such as exponential feeding, feeding based on the average glucose consumption rate and was determined using various feeding methods such as exponential feeding, feeding based on the average glucose consumption rate and on the oxygen uptake rate and etc. Our result shows that glucose feeding, based on the oxygen uptake rate is a very simple, efficient and robust method, especially when oxygen is consumed as a substrate for the bioconversion. Using the above glucose feeding strategy under the optimized condition, 255 g/L of sodium gluconate concentration, 12 g/L/hr of productivity and 95% of glucose conversion yield were achieved with A. niger ACM53.

• The Korean Journal of Physiology
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• v.2 no.2
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• pp.21-31
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• 1968

The appearance rates of antipyrine and urea into cerebrospinal fluid from blood were studied in the rabbits which were in the state of hypotension and of high permeability in the capillary beds following injection of histamine. The alteration in the distribution of electrolytes among various compartments of the brain and the permeability characteristics in the blood-cerebrospinal fluid barrier were also observed. Adult male rabbits, weighing around 2 kg, were used. Twenty four rabbits were divided into 3 groups. Besides the control group, histamine treated rabbits were categorized into 2 groups. $H_1$ consisted of the rabbits showing moderate responses to histamine and ranging from 62 to 80 mmHg in their mean anterial blood pressure. The animals which belong to $H_2-group$ showed severe responses to histamine and the mean anterial blood pressures dropped to 30-50 mmHg. Animals were anesthetized with nembutal, 30mg/kg i.v. The mean arterial blood pressure was read by means of the mercury manometer connected to the femoral artery. The animals, treated with histamine, were kept in hypotensive state at least for 40 minutes before the administration of the test-substances. The test-substances, 300 mg of urea and 200 mg of antipyrine, were dissolved in 3 ml of distilled water and were injected into the ear vein of the rabbit. After 10 minutes elapsed arterial blood sample was taken from the femoral artery and cerebrospinal fluid from the cisterna magna. Brain tissues were also analysed with respect to electrolytes in order to observe the disturbances in the electrolytes balance as well as in the function of the central nervous system. The results obtained were as follow: 1. The ratio of antipyrine concentration in cerebrospinal fluid to that of arterial blood plasma, that was the distribution ratio, was close to unity, revealing a well established equilibrium between the compartments of blood and cerebrospinal fluid in 10 minutes. In other words, there was no diffusion barrier with regard to antipyrine. The ratios over unity which were frequently seen in the histamine treated animals were attributable to the early penetration of the substance into the cerebrospinal fluid. 2. The appearance rates of urea into the cerebrospinal fluid in the histamine treated rabbits were higher in comparison with those of in the control animals. The increasing tendency in the rates was particularly remarkable in the $H_2-group$, showing the enhanced penetration of urea across the boondary. 3. In the htisamine treated $H_2-group$ the concentration of potassium in the blood plasma and cerebrospinal fluid well exceeded the control values and showed 8.5 and 9.0 mEq/l in average, respectively. Simultaneous drops in the brain tissue water were noticed, suggesting the leakage of intracellular potassium. 4. There was a coincidence in the rising pattern of potassium in the blood plasma and in the cerebrospinal fluid of $H_2-group$ and at least partial removal of the blood-cerebrospinal fluid barrier with respect to potassium was suggested in these animals. 5. The concentration of sodium in the blood plasma or in the cerebrospinal fluid showed no significant changes following histamine injection. However, sodium in the brain tissue revealed slight elevation in the histamine treated groups. 6. The ratios of the concentrations of potassium to those of sodium, [K]/[Na] in the brain tissues, were 1.92 in the control 1.82 in the $H_1$ and 1.52 in the $H_2-group$, respectively. The marked drop in the $H_2-group$ might represent neural dysfunction in the extremely hypotensive rabbits.

• Korean journal of applied entomology
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• v.24 no.2 s.63
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• pp.97-101
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• 1985

Pathogenic variations of Xanthomonas campestris pv. oryzae were observed to Korean rice cultivars depending upon isolates in the same pathotype of the pathogen grouped by reactions of Japanese rice differentials. Using 201 Korean isolates of X. campestris pv oryzae 1,307 rice cultivars and promising lines were inoculated, and they were grouped into four varietal groups based on reactions. Of rice cultivars showing similar reactions to X. campestris pv. oryzae, five Korean rice cultivars Milyang 42, Hangangchalbyeo, Pungsanbyeo, Cheongcheongbyeo, and Milyang 23 were selected for classification of the pathogen into races The isolates only virulent to Milyang 23 were designated as race K1, the isolates virulent to Cheongcheongbyeo and Milyang 23 were designated as race K2, the isolates virulent to Pungsanbyeo, Cheongcheongbyeo and Milyang 23 were designated as race K3, the isolates virulent to Hangangchalbyeo, Pungsanbyeo, Cheongcheongbyeo and Milyang 23 were designated as race K4, and the isolates virulent to Milyang 42, Hangangchalbyeo, Pungsanbyeo, Cheongcheongbyeo and Milyang 23 were designated as race K5. Of 201 isolates tested, 114 isolates (56.7%) were classified as race K1, 47 isolates (23.4%) as race K2, 38 isolates (18.9%) as race K3, and 2 isolates (1.0%) as race K4. Reaction in each rice cultivar used as differentials in this test was also compared with that of rice differentials used for classification of X. campestris pv. oryzae into pathotypes in the previous work.

• Publications of The Korean Astronomical Society
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• v.36 no.3
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• pp.47-63
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• 2021

Variability is one of the major characteristics of Active Galactic Nuclei (AGN), and it is used for understanding the energy generation mechanism in the center of AGN and/or related physical phenomena. It it known that there exists a time lag between AGN light curves simultaneously observed at different wavelengths, which can be used as a tool to estimate the size of the area that produce the radiation. In this paper, We present long term near-infrared variability of optically bright type 1 AGN using the Wide-field Infrared Survey Explorer data. From the Milliquas catalogue v6.4, 73 type 1 QSOs/AGN and 140 quasar candidates are selected that are brighter than 18 mag in optical and located within 5 degree around the ecliptic poles. Light curves in the W1 band (3.4 ㎛) and W2 band (4.6 ㎛) during the period of 2010-2019 were constructed for these objects by extracting multi-epoch photometry data from WISE and NEOWISE all sky survey database. Variability was analyzed based on the excess variance and the probability P_var. Applying both criteria, the numbers of variable objects are 19 (i.e., 26%) for confirmed AGN and 12 (i.e., 9%) for AGN candidates. The characteristic time scale of the variability (τ) and the variability amplitude (σ) were derived by fitting the DRW model to W1 and W2 light curves. No significant correlation is found between the W1/W2 magnitude and the derived variability parameters. Based on the subsample that are identified in the X-ray source catalog, there exists little correlation between the X-ray luminosity and the variability parameters. We also found four AGN with changing W1-W2 color.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2335-2347
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• 2023

As medical facilities are usually built at urban areas, special concrete aggregates and evaluation methods are needed to optimize the design of concrete walls by balancing density, thickness, material composition, cost, and other factors. Carbon treatment rooms require a high radiation shielding requirement, as the neutron yield from carbon therapy is much higher than the neutron yield of protons. In this case study, the maximum carbon energy is 430 MeV/u and the maximum current is 0.27 nA from a hybrid particle therapy system. Hospital or facility construction should consider this requirement to design a special heavy concrete. In this work, magnetite is adopted as the major aggregate. Density is determined mainly by the major aggregate content of magnetite, and a heavy concrete test block was constructed for structural tests. The compressive strength is 35.7 MPa. The density ranges from 3.65 g/cm³ to 4.14 g/cm³, and the iron mass content ranges from 53.78% to 60.38% from the 12 cored sample measurements. It was found that there is a linear relationship between density and iron content, and mixing impurities should be the major reason leading to the nonuniform element and density distribution. The effect of this nonuniformity on radiation shielding properties for a carbon treatment room is investigated by three groups of Monte Carlo simulations. Higher density dominates to reduce shielding thickness. However, a higher content of high-Z elements will weaken the shielding strength, especially at a lower dose rate threshold and vice versa. The weakened side effect of a high iron content on the shielding property is obvious at 2.5 µSv=h. Therefore, we should not blindly pursue high Z content in engineering. If the thickness is constrained to 2 m, then the density can be reduced to 3.3 g/cm³, which will save cost by reducing the magnetite composition with 50.44% iron content. If a higher density of 3.9 g/cm³ with 57.65% iron content is selected for construction, then the thickness of the wall can be reduced to 174.2 cm, which will save space for equipment installation.