• Research in Plant Disease
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• v.11 no.2
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• pp.128-134
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• 2005

This study was conducted to elucidate effect of environmental factors on the development of white rot. In order to identify the causal agents causing white rot of Allium crops, we compared DNA profiles of a representative isolate, Sclerotium cepivorum, introduced from foreign country with Korean isolates using UP-PCR. As a result, Sclerotium isolates forming round-shaped sclerotia were identified as Sclerotium cepivorum pertaining in UP-PCR b group and Sclerotium isolates farming anamorphic-shaped sclerotia presumed to be a novel species of Sclerotium based on DNA profiles of UP-PCR. There was a big difference in DNA band pattern between two species of Sclerotium isolated in Korea. Electron micrographs of scanning electron microscope and transmission electron microscope showed morphological differences in sclerotial surface structure and rind layers between two species of Sclerotium. There were more wrinkles and pore spaces on sclerotial surface of Sclerotium sp. forming anamorphic-shaped sclerotia than that of Sclerotium cepivorum forming round-shaped sclerotia. Both of two white rot pathogens grew well at the temperature range of $10-25^{\circ}C$ with optimal temperature of $20^{\circ}C$. Sclerotia of the two pathogens were well formed at $20^{\circ}C$ and well germinated at the temperature range of $20-24^{\circ}C$, Effect of pre-incubation of sclerotia on destruction of sclerotial dormancy of two pathogens was evaluated through storing sclerotia under different temperature condition. The sclerotia of the two pathogens showed an increased capacity to germinate on potato dextroise agar when the sclerotia were incubated for 7 days at $10^{\circ}C$ after pre-treatment at $35^{\circ}C$ for 7 days. At that time, germination rate of Sclerotium sp. and 5. cepivorum was $100\%\;and\;70\%$, respectively. Flooding period and treatment temperature had an effect on sclerotial survival rate of the two pathogens. As flooding period and treatment temperature increased, sclerotial germination rate of the two pathogens decreased. It was confirmed that soil humidity played an important role on development of white rot. It was the highest disease incidence of garlic white rot when garlic were sown at potted soils infested with the two pathogens and adjusted soil humidity to $15\%$ (field moisture capacity, about -300 mb). As soil humidity increase or decrease based on $15\%$ of soil humidity, disease incidence decreased move and more.

• Radiation Oncology Journal
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• v.15 no.1
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• pp.71-78
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• 1997

Purpose : To collect beam data for dynamic wedge fields using conventional measurement tools without the multi-detector system, such as the linear diode detectors or ionization chambers. Materials and Methods : The accelerator CL 2100 C/D has two photon energies of 6MV and 15MV with dynamic wedge an91es of 15o, 30o, 45o and 60o. Wedge transmission factors, percentage depth doses(PDD's) and dose Profiles were measured. The measurements for wedge transmission factors are performed for field sizes ranging from $4\times4cm^2\;to\;20\times20cm^2$ in 1-2cm steps. Various rectangular field sizes are also measured for each photon energy of 6MV and 15MV, with the combination of each dynamic wedge angle of 15o 30o. 45o and 60o. These factors are compared to the calculated wedge factors using STT(Segmented Treatment Table) value. PDD's are measured with the film and the chamber in water Phantom for fixed square field. Converting parameters for film data to chamber data could be obtained from this procedure. The PDD's for dynamic wedged fields could be obtained from film dosimetry by using the converting parameters without using ionization chamber. Dose profiles are obtained from interpolation and STT weighted superposition of data through selected asymmetric static field measurement using ionization chamber. Results : The measured values of wedge transmission factors show good agreement to the calculated values The wedge factors of rectangular fields for constant V-field were equal to those of square fields The differences between open fields' PDDs and those from dynamic fields are insignificant. Dose profiles from superposition method showed acceptable range of accuracy(maximum 2% error) when we compare to those from film dosimetry. Conclusion : The results from this superposition method showed that commissionning of dynamic wedge could be done with conventional dosimetric tools such as Point detector system and film dosimetry winthin maximum 2% error range of accuracy.

• Geophysics and Geophysical Exploration
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• v.8 no.1
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• pp.7-17
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• 2005

The determination of seismic velocities in refractors for near-surface seismic refraction investigations is an ill-posed problem. Small variations in the computed time parameters can result in quite large lateral variations in the derived velocities, which are often artefacts of the inversion algorithms. Such artefacts are usually not recognized or corrected with forward modelling. Therefore, if detailed refractor models are sought with model based inversion, then detailed starting models are required. The usual source of artefacts in seismic velocities is irregular refractors. Under most circumstances, the variable migration of the generalized reciprocal method (GRM) is able to accommodate irregular interfaces and generate detailed starting models of the refractor. However, where the very-near-surface environment of the Earth is also irregular, the efficacy of the GRM is reduced, and weathering corrections can be necessary. Standard methods for correcting for surface irregularities are usually not practical where the very-near-surface irregularities are of limited lateral extent. In such circumstances, the GRM smoothing statics method (SSM) is a simple and robust approach, which can facilitate more-accurate estimates of refractor velocities. The GRM SSM generates a smoothing 'statics' correction by subtracting an average of the time-depths computed with a range of XY values from the time-depths computed with a zero XY value (where the XY value is the separation between the receivers used to compute the time-depth). The time-depths to the deeper target refractors do not vary greatly with varying XY values, and therefore an average is much the same as the optimum value. However, the time-depths for the very-near-surface irregularities migrate laterally with increasing XY values and they are substantially reduced with the averaging process. As a result, the time-depth profile averaged over a range of XY values is effectively corrected for the near-surface irregularities. In addition, the time-depths computed with a Bero XY value are the sum of both the near-surface effects and the time-depths to the target refractor. Therefore, their subtraction generates an approximate 'statics' correction, which in turn, is subtracted from the traveltimes The GRM SSM is essentially a smoothing procedure, rather than a deterministic weathering correction approach, and it is most effective with near-surface irregularities of quite limited lateral extent. Model and case studies demonstrate that the GRM SSM substantially improves the reliability in determining detailed seismic velocities in irregular refractors.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.1
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• pp.1-8
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• 2015

To evaluate accuracy and precision of determination of total alkalinity ($Alk_T$) and carbon dioxide ($TCO_2$) derived from present study, experiment was applied with $CO_2$ CRM (Batch 132, Scripps Institution of Oceanography; $Alk_T=2229.24{\pm}0.39{\mu}mol/kg$, $TCO_2=2032.65{\pm}0.45{\mu}mol/kg$). As the result, average concentration of $Alk_T$ and $TCO_2$ was $2354.09{\mu}mol/kg$ (~5.6% difference with $CO_2$ CRM) and $2089.60{\mu}mol/kg$ (~2.3% difference with $CO_2$ CRM), respectively. For previous method (Gran Titration) by addition $NaHCO_3$ to deionized water($Alk_T$ $2023.33{\mu}mol/kg$), average concentration was $2193.39{\mu}mol/kg$ (sd=57.15, n=7). Whereas, average concentration was $2017.02{\mu}mol/kg$ (sd=10.98, n=7) for the present study. Recovery yield experiments of total alkalinity in deionized water and seawater were implemented by addition of $NaHCO_3$. The recovery yield of deionized water in the range 0 to $4952.39{\mu}mol/kg$ was 100.8% ($R^2$=0.999), and seawater in the range 0 to $2041.32{\mu}mol/kg$ was 102.3% ($R^2$=0.999). Comparison of $pCO_2$ sensor (PSI $CO_2-Pro^{TM}$) with present method showed very meaningful correlation coefficient ($R^2$=0.977) in the range of 427 to $705{\mu}atm$ and 9.16 to $15.24{\mu}mol/kg$ throught elapsed time for two weeks. Field experiment of diurnal variation of total carbon dioxide was accomplished at Sachon harbor in the coastal waters of East Sea of Korea. Concentration of $Alk_T$ and $TCO_2$ was increased during night, and decreased during daylight hours. The results showed mirror type between $TCO_2$ and dissolved oxygen, which was attributable to photosynthesis and respiration of phytoplankton. Also, open ocean field study was performed to obtain vertical profile of $Alk_T$ and $TCO_2$ in C-C zone (Clarion-Clipperton Fracture Zone), Northeastern Pacific. Average concentrations of $Alk_T$ in the surface mixed layer (0~60 m) and deeper layer below 200 m were $2422.38{\mu}mol/kg$ (sd=78.73, n=20) and $2465.87{\mu}mol/kg$ (sd=57.68, n=103), respectively. And average concentrations of $TCO_2$ were $2134.47{\mu}mol/kg$ (sd=65.4, n=20) and $2431.87{\mu}mol/kg$ (sd=65.02, n=103) in the same depth ranges such as $Alk_T$. Vertical distributions of $Alk_T$ and $TCO_2$ concentrations tended to increase with depth, and analyzed concentrations showed slightly higher than those of previous studies in this area.

• Korean Journal of Soil Science and Fertilizer
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• v.5 no.2
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• pp.1-38
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• 1972

This study, designed to establish a classification system of paddy soils and suitability groups on productivity and management of paddy land based on soil characteristics, has been made for the paddy soils on the Gimje-Mangyeong plains. The morphological, physical and chemical properties of the 15 paddy soil series found on these plains are briefly as follows: Ten soil series (Baeggu, Bongnam, Buyong, Gimje, Gongdeog, Honam, Jeonbug, Jisan, Mangyeong and Suam) have a B horizon (cambic B), two soil series (Geugrag and Hwadong) have a Bt horizon (argillic B), and three soil series (Gwanghwal, Hwagye and Sindab) have no B or Bt horizons. Uniquely, both the Bongnam and Gongdeog series contain a muck layer in the lower part of subsoil. Four soil series (Baeggu, Gongdeog, Gwanghwal and Sindab) generally are bluish gray and dark gray, and eight soil series (Bongnam, Buyong, Gimje, Honam, Jeonbug, Jisan, Mangyeong and Suam) are either gray or grayish brown. Three soil series (Geugrag, Hwadong and Hwagye), however, are partially gleyed in the surface and subsurface, but have a yellowish brown to brown subsoil or substrata. Seven soil series (Bongnam, Buyong, Geugrag, Gimje, Gongdeog, Honam and Hwadong) are of fine clayey texture, three soil series (Baeggu, Jeonbug and Jisan) belong to fine loamy and fine silty, three soil series (Gwanghwal, Mangyeong and Suam) to coarse loamy and coarse silty, and two soil series (Hwagye and Sindab) to sandy and sandy skeletal texture classes. The carbon content of the surface soil ranges from 0.29 to 2.18 percent, mostly 1.0 to 2.0 percent. The total nitrogen content of the surface soil ranges from 0.03 to 0.25 percent, showing a tendency to decrease irregularly with depth. The C/N ratio in the surface soil ranges from 4.6 to 15.5, dominantly from 8 to 10. The C/N ratio in the subsoil and substrata, however, has a wide range from 3.0 to 20.25. The soil reaction ranges from 4.5 to 8.0. All soil series except the Gwanghwal and Mangyeong series belong to the acid reaction class. The cation exchange cpacity in the surface soil ranges from 5 to 13 milliequivalents per 100 grams of soil, and in all the subsoil and substrata except those of a sandy texture, from 10 to 20 milliequivalents per 100 grams of soil. The base saturation of the soil series except Baeggu and Gongdeog is more than 60 percent. The active iron content of the surface soil ranges from 0.45 to 1.81 ppm, easily-reduceable manganese from 15 to 148 ppm, and available silica from 36 to 366 ppm. The iron and manganese are generally accumulated in a similar position (10 to 70cm. depth), and silica occurs in the same horizon with that of iron and manganese, or in the deeper horizons in the soil profile. The properties of each soil series extending from the sea shore towards the continental plains change with distance and they are related with distance (x) as follows: y(surface soil, clay content) = $$-0.2491x^2+6.0388x-1.1251$$ y(subsoil or subsurface soil, clay content) = $$-0.31646x^2+7.84818x-2.50008$$ y(surface soil, organic carbon content) = $$-0.0089x^2+0.2192x+0.1366$$ y(subsoil or subsurface soil, pH) = $$-0.0178x^2-0.04534x+8.3531$$ Soil profile development, soil color, depositional and organic layers, soil texture and soil reaction etc. are thought to be the major items that should be considered in a paddy soil classification. It was found that most of the soils belonging to the moderately well, somewhat poorly and poorly drained fine and medium textured soils and moderately deep fine textured soils over coarse materials, produce higher paddy yields in excess of 3,750 kg/ha. and most of the soils belonging to the coarse textured soils, well drained fine textured soils, moderately deep medium textured soils over coarse materials and saline soils, produce yields less than 3,750kg/ha. Soil texture of the profile, available soil depth, salinity and gleying of the surface and subsurface soils etc. seem to be the major factors determining rice yields, and these factors are considered when establishing suitability groups for paddy land. The great group, group, subgroup, family and series are proposed for the classification categories of paddy soils. The soil series is the basic category of the classification. The argillic horizon (Bt horizon) and cambic horizon (B horizon) are proposed as two diagnostic horizons of great group level for the determination of the morphological properties of soils in the classification. The specific soil characteristics considered in the group and subgroup levels are soil color of the profile (bluish gray, gray or yellowish brown), salinity (salic), depositonal (fluvic) and muck layers (mucky), and gleying of surface and subsurface soils (gleyic). The family levels are classified on the basis of soil reaction, soil texture and gravel content of the profile. The definitions are given on each classification category, diagnostic horizons and specific soil characteristics respectively. The soils on these plains are classified in eight subgroups and examined under the existing classification system. Further, the suitability group, can be divided into two major categories, suitability class and subclass. The soils within a suitability class are similar in potential productivity and limitation on use and management. Class 1 through 4 are distinguished from each other by combination of soil characteristics. Subclasses are divided from classes that have the same kind of dominant limitations such as slope(e), wettness(w), sandy(s), gravels(g), salinity(t) and non-gleying of the surface and subsurface soils(n). The above suitability classes and subclasses are examined, and the definitions are given. Seven subclasses are found on these plains for paddy soils. The classification and suitability group of 15 paddy soil series on the Gimje-Mangyeong plains may now be tabulated as follows.

• Journal of Korean Society of Forest Science
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• v.45 no.1
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• pp.11-25
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• 1979

There was much mass movement at many different mountain side of Peong Chang area in Kwangwon province by the influence of heavy rainfall through August/4 5, 1979. This study have done with the fact observed through the field survey and the information of the former researchers. The results are as follows; 1. Heavy rainfall area with more than 200mm per day and more than 60mm per hour as maximum rainfall during past 6 years, are distributed in the western side of the connecting line through Hoeng Seong, Weonju, Yeongdong, Muju, Namweon and Suncheon, and of the southern sea side of KeongsangNam-do. The heavy rain fan reason in the above area seems to be influenced by the mouktam range and moving direction of depression. 2. Peak point of heavy rainfall distribution always happen during the night time and seems to cause directly mass movement and serious damage. 3. Soil mass movement in Peongchang break out from the course sandy loam soil of granite group and the clay soil of lime stone and shale. Earth have moved along the surface of both bedrock or also the hardpan in case of the lime stone area. 4. Infiltration seems to be rapid on the both bedrock soil, the former is by the soil texture and the latter is by the crumb structure, high humus content and dense root system in surface soil. 5. Topographic pattern of mass movement spot is mostly the concave slope at the valley head or at the upper part of middle slope which run-off can easily come together from the surrounding slope. Soil profile of mass movement spot has wet soil in the lime stone area and loose or deep soil in the granite area. 6. Dominant slope degree of the soil mass movement site has steep slope, mostly, more than 25 degree and slope position that start mass movement is mostly in the range of the middle slope line to ridge line. 7. Vegetation status of soil mass movement area are mostly fire field agriculture area, it's abandoned grass land, young plantation made on the fire field poor forest of the erosion control site and non forest land composed mainly grass and shrubs. Very rare earth sliding can be found in the big tree stands but mostly from the thin soil site on the un-weatherd bed rock. 8. Dangerous condition of soil mass movement and land sliding seems to be estimated by the several environmental factors, namely, vegetation cover, slope degree, slope shape and position, bed rock and soil profile characteristics etc. 9. House break down are mostly happen on the following site, namely, colluvial cone and fan, talus, foot area of concave slope and small terrace or colluvial soil between valley and at the small river side Dangerous house from mass movement could be interpreted by the aerial photo with reference of the surrounding site condition of house and village in the mountain area 10. As a counter plan for the prevention of mass movement damage the technics of it's risk diagnosis and the field survey should be done, and the mass movement control of prevention should be started with the goverment support as soon as possible. The precautionary measures of house and village protection from mass movement damage should be made and executed and considered the protecting forest making around the house and village. 11. Dangerous or safety of house and village from mass movement and flood damage will be indentified and informed to the village people of mountain area through the forest extension work. 12. Clear cutting activity on the steep granite site, fire field making on the steep slope, house or village construction on the dangerous site and fuel collection in the eroded forest or the steep forest land should be surely prohibited When making the management plan the mass movement, soil erosion and flood problem will be concidered and also included the prevention method of disaster.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.3
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• pp.189-201
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• 1977

Some of basic aspects of soil potassium with special reference to soil physical properties were discussed. Data in the Official Soil Series Description(Korea) was analyzed according to soil type, land form, and soil texture to find soil potassium status which may explain different response to potassium application. Exchangeable potassium contents decreased with soil depth irrespective of soil type, land form and soil texture. Change in degree of potassium saturation within soil profile was not so clear as exchangeable potassium but the degree of potassium saturation of A horizon was highest among soil horizon. Soils of terrace and mountain foot slope showed high values both in exchangeable potassium and degree of potassium sauration and only these two soils were classified as soils having exchangeable potassium higher than 0.3 meq per 100g of soil and degree of potassium saturation higher than 5.0%. Exchangeable potassium of fine loamy and fine clayey soils is higher than 0.3 meq per 100g of soil but degree of potassium saturation is lower than 4.0%. Degree of potassium saturation of sandy soils exceeds 5.0% but exchangeable potassium is very low. Soils of rolling, hilly, unmatured and alpine land soils have lower exchangeable potassium and show lower degree of potassium saturation. The highest distribution of exchangeable potassium content irrespective of soil horizons was shown in the range of 0.1-0.2 meq per 100g of soil. The highest distribution of degree of potassium saturation was in the range of 2.0-3.0% in A horizon and 1.0-2.0% in B and C horizons. Of the soil series concerned in this analysis, 27.3% in A horizon, 11.1% in B horizon and 4.0% in C horizon had exchangeable potassium higher than 0.3 meq per 100g of soil and 18.0% in A horizon, 6.3% in B horizon, and 4.1% in C horizon showed degree of potassium saturation higher than 5.0%. The low response of potassium application only to soils in terrace and mountain foot slope may be resulted from the high exchangeable potassium content and high degree of potassium saturation. It is concluded that a great response of potassium application to soils is expected especially in dry season.

• Radiation Oncology Journal
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• v.25 no.4
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• pp.268-277
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• 2007

Purpose: Respiratory motion is a considerable inhibiting factor for precise treatment with stereotactic radiosurgery using the CyberKnife (CK). In this study, we developed a moving phantom to simulate three-dimensional breathing movement and investigated the distortion of dose profiles between the use of a moving phantom and a static phantom. Materials and Methods: The phantom consisted of four pieces of polyethylene; two sheets of Gafchromic film were inserted for dosimetry. Treatment was planned to deliver 30 Gy to virtual tumors of 20, 30, 40, and 50 mm diameters using 104 beams and a single center mode. A specially designed robot produced three-dimensional motion in the right-left, anterior-posterior, and craniocaudal directions of 5, 10 and 20 mm, respectively. Using the optical density of the films as a function of dose, the dose profiles of both static and moving phantoms were measured. Results: The prescribed isodose to cover the virtual tumors on the static phantom were 80% for 20 mm, 84% for 30 mm, 83% for 40 mm and 80% for 50 mm tumors. However, to compensate for the respiratory motion, the minimum isodose levels to cover the moving target were 70% for the $30{\sim}50$ mm diameter tumors and 60% for a 20 mm tumor. For the 20 mm tumor, the gaps between the isodose curves for the static and moving phantoms were 3.2, 3.3, 3.5 and 1.1 mm for the cranial, caudal, right, and left direction, respectively. In the case of the 30 mm tumor, the gaps were 3.9, 4.2, 2.8, 0 mm, respectively. In the case of the 40 mm tumor, the gaps were 4.0, 4.8, 1.1, and 0 mm, respectively. In the case of the 50 mm diameter tumor, the gaps were 3.9, 3.9, 0 and 0 mm, respectively. Conclusion: For a tumor of a 20 mm diameter, the 80% isodose curve can be planned to cover the tumor; a 60% isodose curve will have to be chosen due to the tumor motion. The gap between these 80% and 60% curves is 5 mm. In tumors with diameters of 30, 40 and 50 mm, the whole tumor will be covered if an isodose curve of about 70% is selected, equivalent of placing a respiratory margin of below 5 mm. It was confirmed that during CK treatment for a moving tumor, the range of distortion produced by motion was less than the range of motion itself.

• Korean Journal of Ecology and Environment
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• v.36 no.4 s.105
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• pp.455-462
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• 2003

This study evaluated the change of water quality and chlorophyll - a at the birth stage of a large reclaimed estuarine lake (Lake Hwaong) of which the dike was finally constructed in March, 2002. Physico -chemical parameters and chlorophyll - a were investigated along a longitudinal transect, including 3 in-lake sites and 1 out-lake site from June to November, 2002. Salinity at all in-lake sites was over 21 psu during the study period, indicating that lake is still in the seawater phase. Salinity was periodically diluted at times when precipitation was high, especially in August. Chemocline was established in July near the dam site, and correspondingly vertical profile of dissolved oxygen was very clear during that Period. Total nitrogen and phosphorus concentrations at all lake sites were in the eutrophic range, and they were especially high at the stream inlet site. Nutrients concentration was not much varied vertically but significantly varied temporally, and correlated significantly with precipitation and chlorophyll-a concentration, indicating that inflowing water from the watershed seemed not to improve lake water by dilution but cause eutrophication of the lake, and thereby stimulate phytoplankton development. Based on the analyses of nutrient ratio (N/P) and trophic state deviation, both phosphorus and nitrogen appeared to limit phytoplankton growth in the lake. Phosphorus limitation appeared to be probable at all in-lake sites with being most severe at the stream inlet site. Nitrogen limitation seemed to occur at both in-lake and out-lake sites. These results indicate that in Lake Hwaong experiencing the very early stage of a reclaiming lake, water quality and phytoplankton development appear to be affect-ed largely by salinity and hydrology and nutrients from the inflowing water. Lake biogeochemistry is still very unstable, and thus further long-term study is necessary to understand the effects of seawater to freshwater conversion on lake biology and water chemistry.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1781-1786
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• 2011

This study was conducted to investigate the cause of microbiological contamination in yogurt and evaluate the effect of physicochemical treatment on the growth inhibition of Hanseniaspora uvarum isolated from yogurt. The yeast strain Hanseniaspora uvarum Y1 was subjected to heat and pH treatments. H. uvarum Y1 was killed at $70^{\circ}C$ and $80^{\circ}C$ after 15 min and survived in a wide pH range from pH 2 to 9. However, it did not survive under pH 1 and over pH 10. In a disk diffusion susceptibility test on H. uvarum Y1, a clear zone (5 mm) of growth inhibition was observed upon treatment with electrolyzed water. The effect of ozone gas on the growth of H. uvarum Y1 was evaluated by viable cell count. Initial cell numbers of $10^2$ and $10^3$ CFU/mL of H. uvarum Y1 were completely killed by treatment for 10 and 30 min, respectively. H. uvarum Y1 was also sterilized by microwave treatment for 1 min. When treated with gamma-irradiation, the rate of killing of H. uvarum Y1 was proportional to the irradiation dose. and complete killing occurred at a dose of 50 kGy.