• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.295-303
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• 2000

The water clarification efficiency was examined in a shallow wetland where dense vegetation was formed naturally in an abandoned paddy field. And, also two enclosure experiments were carried out to measure the effects of materials exchange between sediment and the overlying water with the existence of vegetation and accumulated litter. The hydraulic retention time of wetland was regulated in 1.2 day. The removal rates of SS (56%) and $NO_3-N$ (61%) were high, considering its short retention time. However, removal efficiencies of VSS (28%), COD (14%), DOC (1%),and TP (0.2%) were relatively lower. This low removal efficiencies were thought to be due to the release of dissolved form of organic matter and phosphorus from the sediment. Most of constituents except nitrate were higher in the enclosure at the beginning of enclosure installation than that of the outflowing water from wetland. And then, it has fluctuated and decreased with time. The wetland was in equilibrium state of settling, accumulation of organic debris, and regeneration of dissolved material from sediment. So ultimately high primary production by dense vegetation in the wetland may be the reason of unfavorable or low treatment efficiency of wetland after many years of operation for wastewater treatment. However, the water quality of effluent from the wetland showed smaller variation and better condition than that of inflow, especially during storm events. It can be concluded that this wetland is suitable for the improvement of water quality from nonpoint sources.

• Research in Plant Disease
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• v.21 no.3
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• pp.235-242
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• 2015

A 2014 nationwide survey in radish fields investigated the distribution of common viruses and possible emerging viruses. Radish leaves with virus-like symptoms were collected and 108 samples assayed by RT-PCR using specific primers for Radish mosaic virus (RaMV), Cucumber mosaic virus (CMV), and Turnip mosaic virus (TuMV); 47 samples were TuMV positive, and RaMV and CMV were detected in 3 and 2 samples, respectively. No samples showed double infection of TuMV/RaMV, or RaMV/CMV, but two double infections of TuMV/CMV were detected. TuMV isolates were sorted by symptom severity, and three isolates (R007-mild; R041 and R065-severe) selected for BLAST and phylogenetic analysis, which indicated that the coat protein (CP) of these isolates (R007, R041, and R065) have approx. 98-99% homology to a previously reported TuMV isolate. RaMV CP showed approx. 99% homology to a previously reported isolate, and the CMV CP is identical to a previously reported Korean isolate (GenBank : GU327368). Three isolates of TuMV showing different pathogenicity (degree of symptom severity) will be valuable to study determinants of pathogenicity.

• Radiation Oncology Journal
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• v.11 no.2
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• pp.431-437
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• 1993

An important problem in radiosurgery is the utilization of the proper beam parameters, to which dose shape is sensitive. Streotactic radiosurgery techniques for a linear accelerator typically, use circular radiation fields with multiple arcs to produce an spherical radiation distribution. Target volumes are irregular in shape for a certain case, and spherical distributions can irradiate normal tissues to high dose as well as the target region. The current improvement to dose distribution utilizes treating multiple isocenters or weighting various arcs to change treatment volume shape. in this paper another promising study relies upon dynamically shaping the treatment beam to fit the beam's eye view of the target. This conformal irradiation technique was evaluated by means of visual three dimensional dose distribution, dose volume histograms to the target volume and surrounding normal brain. It is shown that using even less arcs than multiple isocenter irradiation technique, the conformal therapy yields comparable dose gradients and superior homogeneity of dose within the target volume.

• Journal of Korea Water Resources Association
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• v.42 no.2
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• pp.149-160
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• 2009

The objective of this study is to suggest parameter regionalization scheme which is integrated two multivariate statistical methods: principal components analysis(PCA) and hierarchical cluster analysis(HCA). This technique is to apply semi-distributed rainfall-runoff model on ungauged catchments. 7 catchment characteristics (area, mean altitude, mean slope, ratio of forest, water content at saturation, field capacity and wilting point) are estimated for 109 mid-sized sub-basins. The first two components from PCA results account for 82.11% of the total variance in the dataset. Component 1 is related to the location of the catchments relevant to the altitude and Component 2 is connected with the area of these. 103 ungauged catchments are clustered using HCA as the following 6 groups: Goesan 23, Andong 6, Imha 5, Hapcheon 21, Yongdam 4, Seomjin 44. SWAT model is used to simulate runoff and the parameters of the model on the 6 gauged basins are estimated. The model parameters were regionalized for Soyang, Chungju and Daecheong dam basins which are assumed as ungauged ones. The model efficiency coefficients of the simulated inflows for these three dams were at least 0.8. These results also mean that goodness of fit is high to the observed inflows. This research will contribute to estimate and analyze hydrologic components on the ungauged catchments.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.4
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• pp.379-385
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• 1987

A field experiment was conducted to find out the effects of liming (soil pH) and sources of N on the chemical constituents of soil and leaf lamina of burley tobacco. Treatments consisted of liming (nonliming, liming to soil pH 5.5 and 6.5) as the main plot and N sources［compound fertilizer of containing 3.9% $NH_4-N$ and 6.1% $NH_2-N,\;NaNO_3,\;(NH_2)_2CO\;and\;(NH_4)_2SO_4$］as the sub-plot. The soil pH was high in $NaNO_2$ plot, while low in $(NH_4)_2SO_4$. But the differences of Ca concentration in top soil among N sources were not detected. The $NO_3-N$ concentration in top soil was high in high limed and $NaNO_3$ plot. The $NO_3-N$ content of leaf (lamina) at 75 days after transplanting was high in $NaNO_3$ plot and CaO con-tent of leaf at 45 days after transplanting was high in high limed plot. But neither liming nor N source had effect on the contents of total nitrogen, $P_2-O_{5}\;and\;K_2O$ of leaf during growing season. There was no significant differences in total alkaloid and total nitrogen contents of cured leaf (lamina) to liming and N source. But when the source of N was $NaNO_3$, the content of total alkaloid was increased by adding lime. When the source of N was $(NH_4$)_2SO_4$, the content of $K_2O$ in cured leaf was high while CaO was low. But neither liming nor N source had effect on the contents of $P_2-O_{5}$ and MgO in cured leaf.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.4
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• pp.327-337
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• 1996

A field experiment was conducted at SNU Experimental Livestock Farm, Suweon in 1995 to determine effect of planting date on forage performance of wm hybrids of four different maturity groups. A split-plot design replicated three times was used, with com hybrids representing four maturity groups (115, 118, 121 and 125 days) being the main plots and planting dates (3124, 415, 415, 425, 515 and 5/15) the sub-plots. 1. Days to emergence and percent emergence from the March 24 planting were, on the average, 36 days and 58%, respectively, but those from the April 5 to May 15 planting averaged 12 days and 92%, respectively. 2. Plant and ear heights increased gradually as the dates of planting were delayed except the May 15 planting, however, percent ear was decreased as the dates of planting were delayed. There was a trend for the mean lodging percentage of the hybrids to be higher as the planting date was delayed. 3. The 115-and 118-day mediumearly maturing hybrids harvested on August 18 produced silages with a dry matter content between 27 and 30% at all planting dates except the May 15 planting, while the 121-and 125-day medium-late maturing hybrids produced silages with a dry matter wntent less than 27% regardless of any planting dates. 4. There were no significant differences in mean dry matter yield among the hybrids, but significant mean TDN yield differences were found. The 115-, 118- and 125-day hybrids had significantly higher mean TDN yield than the 121-day hybrid. There were significant differences in mean dry matter and TDN yields among the planting dates. The mean dry matter and TDN yields from the April 5, 15 and 25 plantings were significantly higher than those of other plantings, however, there were no significant differences in mean TDN yield among the April 5, April 15 and April 25 plantings. No significant planting date $\times$ maturity interactions were found for both the dry matter and TDN yields. 5. Mean stover NDF and ADF contents of the 115- and 118day hybrids were higher than those of the 121- and 125-day hybrids, but the reverse was true for mean stover IVDMD and RFV. Mean stover NDF an ADF contents increased with earlier plantings, but mean stover IVDMD and RFV increased when planting was delayed. Results of this experiment indicate that for corn planting in central and northern areas of Korea, early to mid-April may be the right time with the 115-to 118-day maturity hybrids when silage making before August 20 is taken into consideration.

• Journal of Information Management
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• v.35 no.1
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• pp.1-27
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• 2004

To share knowledge efficiently among our members on the basis of knowledge management system, first of all, we need to systematically design the knowledge classification scheme that we can classify these knowledge well. The objective of this study is to construct the most suitable knowledge classification scheme that all of us can share them in Korea Atomic Energy Research Institute (KAERI). To construct the knowledge classification scheme all over the our organization, we established a few principles to design it and examined related many classification schemes. And I carried out 3 steps to complete the best desirable KAERI's knowledge classification scheme, that is, (1) the step to design a draft of the knowledge classification scheme, (2) the step to revise a draft of the knowledge classification scheme, (3) the step to verify the revised scheme and to decide its scheme. The scheme completed as a results of this study is consisted of total 218 items : sections of 8 items, classes of 43 items and sub-classes of 167 items. I expect that the knowledge classification scheme designed as the results of this study can be played an important role as the frame to efficiently share knowledge among our members when we introduce knowledge management system in our organization. In addition, I expect that steps to design its scheme as well as this scheme itself can be applied when design a knowledge classification scheme at the other R&D institutes and enterprises.

• Journal of the Korean GEO-environmental Society
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• v.13 no.10
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• pp.25-32
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• 2012

The application of electrical resistivity, which is related to charge mobility, has increased in the field of geotechnical engineering for the detection of underground cavern, faults and subsurface pollution level. The purpose of this study is to investigate the variation of electrical resistivity due to temperature change. Sand-silt mixture specimens prepared in the square freezing nylon cell are frozen in the frozen chamber. Four electrodes are attached on the four side walls of the freezing cell for the measurement of electrical resistance during temperature change. Electrical resistances of sand-silt mixtures with different degrees of saturation (0%, 2.5%, 5%, 10%, 20%, 40%, 60% and 100%) are measured as the temperature of specimens decrease from $20^{\circ}C$ to $-10^{\circ}C$. The electrical resistances determined by Ohm's law are transformed into the electrical resistivity by calibration. Experimental results show that the higher degree of saturation, the lower electrical resistivity at $20^{\circ}C$. Electrical resistivity gradually increases as the temperature decrease from $20^{\circ}C$ to $0^{\circ}C$. For the specimens with the degree of saturation of 15% or higer, electrical resistivity dramatically changes near the temperature of $0^{\circ}C$. In addition, very high electrical resistivity is observed regardless of the degree of saturation if the specimens are frozen. This study provides the fundamental information of electrical resistivity according to the soil freezing and temperature change demonstrates that electrical resistivity be a practical method for frozen soil investigation.

• Journal of The Korean Association For Science Education
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• v.38 no.5
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• pp.649-665
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• 2018

In this study, we extracted the core competencies of makers through the analysis of critical incident technique and behavioral event interview to explore the nature and attributes of maker education, and then we developed a maker competency model based on these core competencies. As a result, six competency groups and 23 sub-competencies were extracted. In other words, we were able to confirm the existence of integrated thinking competency group consisting of four competencies made up of 'analytic thinking', 'intuitive thinking', 'visual thinking', and 'empirical thinking' and that of collaborative competency group with four competencies of 'sharing', 'communication', 'conflict management', and 'scrupulosity'. In addition, we could also confirm the existence of making mind competency group, which is composed of four competencies namely 'interest in various areas', 'challenge consciousness', 'failure management', and 'pleasure of the making process'. We could also confirm that human-centered competence group consisting of two competencies of 'humanity' and 'user-oriented' and the problem-finding competence group consisting of two competencies of 'observation' and 'recognition of discomfort in daily life'. Lastly, the making practice competency group is composed of seven competencies: 'understanding making tool', 'understanding electricity', 'understanding programming', 'planning', 'hand knowledge', 'information search', and 'direct execution'. We discussed educational implications of these findings.

• Journal of Digital Contents Society
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• v.17 no.1
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• pp.51-57
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• 2016

Distributed Computing attempts to harness a massive computing power using a great numbers of idle PCs resource distributed linked to the internet and processes a variety of applications parallel way such as bio, climate, cryptology, and astronomy. In this paper, we develop internet-distributed computing environment, so that we can analyze High Resolution Rainfall Prediction application in meteorological field. For analyze the rainfall forecast in Korea peninsula, we used QPM(Quantitative Precipitation Model) that is a mesoscale forecasting model. It needs to a lot of time to construct model which consisted of 27KM grid spacing, also the efficiency is degraded. On the other hand, based on this model it is easy to understand the distribution of rainfall calculated in accordance with the detailed topography of the area represented by a small terrain model reflecting the effects 3km radius of detail and terrain can improve the computational efficiency. The model is broken down into detailed area greater the required parallelism and increases the number of compute nodes that efficiency is increased linearly.. This model is distributed divided in two sub-grid distributed units of work to be done in the domain of $20{\times}20$ is networked computing resources.