• Journal of the Korean Society of Groundwater Environment
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• v.7 no.1
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• pp.32-46
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• 2000

Hydrogeochemical and isotope ($\delta$$^{18}$ O, $\delta$D, $^3$H, $\delta$$^{13}$ C, $\delta$$^{34}$ S, $^{87}$ Sr/$^{86}$ Sr) studies of various kinds of waters (thermal groundwater, deep groundwater, shallow groundwater, and surface water) from the Yusung area were carried out in order to elucidate their geochemical characteristics such as distribution and behaviour of major/minor elements, geochemical evolution, reservoir temperature, and water-rock interaction of the thermal groundwater. Thermal groundwater of the Yusung area is formed by heating at depth during deep circlulation of groundwater and is evolved into Na-HCO$_3$type water by hydrolysis of silicate minerals with calcite precipitation and mixing of shallow groundwater. High NO$_3$contents of many thermal and deep groundwater samples indicate that the thermal or deep groundwaters were mixed with contaminated shallow groundwater and/or surface water. $\delta$$^{18}$ O and $\delta$D are plotted around the global meteoric water line and there are no differences between the various types of water. Tritium contents of shallow groundwater, deep groundwater and thermal groundwater are quite different, but show that the thermal groundwater was mixed with surface water and/or shallow groundwater during uprising to surface after being heated at depths. $\delta$$^{13}$ C values of all water samples are very low (average -16.3$\textperthousand$%o). Such low $\delta$$^{13}$ C values indicate that the source of carbon is organic material and all waters from the Yusung area were affected by $CO_2$ gas originated from near surface environment. $\delta$$^{34}$ S values show mixing properties of thermal groundwater and shallow groundwater. Based on $^{87}$ Sr/$^{86}$ Sr values, Ca is thought to be originated from the dissolution of plagioclase. Reservoir temperature at depth is estimated to be 100~1$25^{\circ}C$ by calculation of equilibrium method of multiphase system. Therefore, the thermal groundwaters from the Yusung area were formed by heating at depths and evolved by water-rock interaction and mixing with shallow groundwater.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.2
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• pp.89-95
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• 1979

A field experiment was conducted to investigate the effects of season of application and particle-size distribution of silicate fertilizer on rice yields of Indica type, Milyang 23 and Japonica type Jinheung. The application of silicate fertilizer at the rate of 250kg per 10a increased greatly rice yields. Rice yields were a little higher when silicate fertilizer was applied at transplanting time (Spring application) than applied in Autumn of preceding year (Autumn application) and increased with increasing content of fine particles of silicate fertilizer. However, the difference in effects between the season of application was insignificant and the silicate fertilizer of particles to pass by 100% through a 8 mesh sieve and by 60% through a 25 mesh sieve, 8-25(60%) was as effective as the one to meet silicate fertilizer specifications, 10-28(60%). Silica content of plant samples did not show any significant effects of season of application and particle-size distribution of silicate fertilizer, whereas samples taken at 50 days after tran planting showed significant effects of season of application and particle-size distribution. Silica content of straw of Jinheung was highest when 8-25(60%) was applied. Silica content of soils before the experiment was 36.7 ppm and the content increased to range of 159.5-273.8 ppm and 80.3-134.4 ppm in the plots of Spring application and Autumn application respectively.

• Weed & Turfgrass Science
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• v.5 no.1
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• pp.29-34
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• 2016

Large patch disease in Zoysia japonica Steud. is the most destructive disease in turfgrass. For large patch management, it has been dependent on chemical controls but pesticides are harmful to soil, water and biodiversity. In this study, we evaluated 4 Streptomyces spp. strains (S2, S5, S8 and S12) which were selected in previous studies using metagenome approaches. Root colonization of the strains, large patch suppressing effect and the pathogen density change in actual golf course were investigated to evaluate biological control potential of the strains. All strains exhibited reliable root colonization ability that strains populations were higher than $6log\;cfu\;g^{-1}$ in turfgrass rhizosphere. The pathogen density, with S8 treatment, was detected average of 0.7 after a week and average of 1.2 after 4 weeks. Disease control and suppressive the pathogen population by S8 strain showed higher efficiency than other strains. S8 was applied in an actual golf course for the large patch control and pathogen density. The pathogen density in S8 treatment plot was detected below 1.6 per toothpick and lower compared with untreated plot. The results indicated that pathogen density was suppressed by S8 and the stain has great potential as a biological control agent for the large patch.

• Korean Journal of Environmental Biology
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• v.39 no.2
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• pp.245-257
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• 2021

Ulleungdo, a volcanic island, has different climate, soil, and topography characteristics from inland of the Korean Peninsula. Its agriculture also exhibits distinctive features. This study focused on floristic compositions and characteristics of crop lands in Ulleungdo. Flora surveys were conducted for 37 areas three times, one in May of 2016, one in July of 2020, and one in August of 2020. Results showed that vascular plants of crop lands in Ulleungdo included 186 taxa of 53 families, 132 genera, 160 species, 14 varieties, five subspecies, and five hybrids. Asteraceae had the most diverse species (33 taxa), followed by Poaceae (25 taxa), Fabaceae (12 taxa), Polygonaceae (11 taxa), and Liliaceae (nine taxa). The biological type of crop lands in Ulleungdo island was determined to be Th-R₅-D₄-e type. Rare plants were found for nine taxa: Athyrium acutipinnulum Kodama ex Nakai, Sedum takasimense Nakai, Rubus takesimensis Nakai, Dystaenia takesimana (Nakai) Kitag., Ligustrum foliosum Nakai, Aster pseudoglehni Y.Lim, Cirsium nipponicum (Maxim.) Makino, Lilium hansonii Leichtlin ex D.D.T.Moore, and Polygonatum robustum (Korsh.) Nakai. In addition, 45 taxa contained naturalized plants of 13 families, 33 genera, 44 species, and one variety. Urbanization and naturalization indices were 13.9%, and 24.2%, respectively.

• Applied Biological Chemistry
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• v.14 no.1
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• pp.9-18
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• 1971

In order to obtain basic information on the production of single cell protein from petroleum, more than 400 yeast strains were isolated from various soil samples in Korea utilizing petroleum hydrocarbon as the sole carbon source. A yeast strain showing the highest cell yield among the isolated strains was selected and identified. The optimal culture condition was searched in the flasks shaken throughout the procedure. And the growing characteristics for the selected yeast strain and chemical analysis of the yeast cell component were carried out. The results obtained were as follows: 1. The selected yeast strain was identified as Candida curvata and we named it Candida curvata-SNU 70. 2. The composition of the medium proposed for the present yeast strain is: Light Gas Oil 30ml, Urea 400mg, Ammonium sulfate 100mg, Potasium phosphate (monobasic) 670mg, Sodium phosphate (dibasic) 330mg, Magnesium sulfate 500mg, Calcium carbonate 3g, Yeast extract 50mg, Tween 20 0.05ml, Tap water 1,000ml. 3. Other culture conditions employed for the yeast were pH 5.5-7.0, temp. $30^{\circ}C$ under an affluent aerobic state. 4. Addition of light gas oil in portions to the culture media as the growth proceeded was more effective, especially in the cultivation on the higher oil concentration media. 5. Studies on the propagation of the yeast cells in the light gas oil medium revealed that the yeast has the lag phase lasted 16 hours and the logarithmic growth phase covered 16 to 28 hours. The specific growth rate was about $0.22\;hr^{-1}$ and doubling time was 3.2 hrs. during the logarithmic growth phase. 6. Under the cultural condition employed, the cell yield against the amount of light gas oil (wt%) was 16.1% and the protein content of the dried yeast cells was 48.4%.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.6
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• pp.339-344
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• 2006

A lot of organic wastes have been produced from diverse industries, they must be tested by the regulation of fertilizer control act if reuse the organic wastes for agricultural utilization. The regulation has had only two criteria; the content of organic matter and 8 heavy metals. This study was conducted to evaluation trace element (boron, cobalt, molybdenum, and selenium) and distribution of organic compounds with different classification for complement the regulation in 16 organic waste materials(62 samples) collected from different regions and industries. Contents of boron(leather industry sludge, $154.2mg\;kg^{-1}$; food company sludge, $57.1mg\;kg^{-1}$), cobalt(industrial area sewage sludge, $95.2mg\;kg^{-1}$; metropolitan sewage sludge, $22.9mg\;kg^{-1}$), molybdenum(metropolitan sewage sludge, $40.1mg\;kg^{-1}$; food company sludge, $16.8mg\;kg^{-1}$), selenium (fiber industry sludge, $28.1mg\;kg^{-1}$; leather industry sludge, $16.9mg\;kg^{-1}$; food company sludge, $15.9mg\;kg^{-1}$) were highest compare to the other organic wastes. Total PAHs contents were the highest in paper-mill manufacture($3,462ug\;kg^{-1}$), and among the 16 PAHs, naphthalene, phenanthrene, pyrene, fluoroanthene, Anthracene and acenaphthene were detected more clearly than others in all kinds of organic resources.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.2
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• pp.113-118
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• 2011

This study was aimed to develop blend films by rice by-product (rice-hull and rice-bran) and bio-degradable materials. The rice by-product was firstly prepared from the pulverizing for making fine powder. Bio-degradable materials could be prepared by melting at high temperature. The mixture of the fine powder of rice by-product and melted bio-degradable materials was then blended and cast into films. The obtained films were investigated on their morphology, secondary structures and properties by using SEM, ICP and ASTM, respectively. Mechanical properties and degradability of these films were measured and compared to those of the PE films. Mechanical strength of bio-films was higher than that of PE films, however elongation ratio showed lower percent than that of PE film. In addition, bio-film could be degraded into fragments within 3 months under the field condition of normal upland crop cultivation. Bio-degradable mulching film indicated great potential for agronomic use as a new source of bio-degradable material.

• Korean journal of applied entomology
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• v.55 no.4
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• pp.377-381
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• 2016

The Baermann funnel method requires approximately four Kimwipe tissues for research a nematode count under a stereo microscope. To select more efficient and economical nematode extraction paper for nematode extraction, 15 different kinds of tissue papers were tested and compared with Kimwipe tissues. Nematode species used in the extraction efficiency tests include juvenile (J2) of Heterodera sp., J2 of Meloidogyne sp., Pratylenchus sp., Rhabditis sp., Acrobeloides sp., Panagrolaimus sp., Poikilolaimus sp. and Diplogasterida. The extraction efficiency varied between 42.0 to 88.8%. Considering costs, extraction efficacy, and clarity, the Pulling Kitchen Towel (Monalisa Co., Korea) is the best tissue, with clarity A, isolation efficiency of 69.4% (not significantly different compared to Kimwipe 1 ply 88.8%), and 1/2 costs per isolation of Kimwipe 2 ply.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.209-210
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• 2016

우리나라의 연평균강수량은 약 1362 mm이며, 총강수량의 약 30% 이상이 증발산을 통해 손실되고 있다고 추정되어지고 있다. 증발산은 물 수지 분석에 있어 매우 중요한 성분이며, 많은 부분을 차지하지만 다른 요인들에 비해 직접적인 관측이 어려워 과거에는 경험식을 사용하거나 단순하게 가정에 의해 결정해 왔다. 또한 기상자료로부터 증발산량을 추정하거나 증발접시나 추정식으로 잠재증발산을 추정하고 있다. 또한 최근 기후변화의 가속화에 따른 홍수의 가뭄의 강도와 빈도가 높아지고 있으며, 이에 따라 수자원 관리에 있어서 기초수문조사 항목에 많은 변화를 요구하고 있다. 그 결과 2007년 4월 하천법 개정으로 증발산량 및 토양수분량이 기초수문조사 항목으로 추가되었으며, K-water 연구원에서는 용담시험유역에 플럭스타워를 설치하였고 현재 운영 중에 있다. 덕유산 플럭스타워는 용담시험유역 내에 위치한 금강 수계 구량천 상류부의 덕곡제 유역 내에 설치하였으며, 2011년 4월부터 실제 증발산량을 관측하고 있다. 동경 $127^{\circ}$42'23" ~ $127^{\circ}$44'53", 북위 $35^{\circ}$50'47" ~ $35^{\circ}$52'50"사이로 중부지방에 위치한 유일한 증발산관측 타워이다. 유역 면적은 9.27 km2으로 유로연장 3.48 km, 유역 평균폭 2.66 km, 형상계수는 0.77이며, 덕곡제플럭스 타워 주변의 토지이용은 대부분 산림으로 구성되어 있으며, 침활 혼효림과 낙엽송림으로 임상 분포가 이루어져 있다. 주요 관측기기로는 3차원 풍향 풍속계, $CO_2/H_2O$ 기체분석기, 순복사 측정 센서, 지중열플럭스 측정 센서 등이 있다. 2011년부터 측정된 자료를 바탕으로 에디공분산 방법을 이용하여 증발산량을 측정하였으며, 30분간의 데이터 18,000개 중 취득률 90 % 이상의 데이터를 대상을 분석을 실시하였다. 2011 ~ 2015년도 증발산량 분석 결과는 아래의 표와 같다. 증발산의 패턴은 1월부터 서서히 증가하지만 활발하지는 않고, 4월부터 매우 활발해져 8월에 최대치에 이른다. 10월부터 증발산량은 급격히 감소하기 시작하며 11, 12월에는 증발산이 거의 발생하지 않는 공통적인 경향을 보였다. 2013년 8, 9월은 다른 해와 다른 경향을 보이고 있는데, 이는 2013년 8, 9월에 강우가 많이 발생하여 증발산량이 감소하였기 때문으로 판단된다. 2015년 8월은 다른 년도와 비교했을 때, 매우 높은 증발산량을 보이는데 이는 2015년 8월에 많은 강우에도 식생이 활발하게 작용하였기 때문으로 판단된다.

• Journal of Climate Change Research
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• v.1 no.2
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• pp.121-131
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• 2010

This study was carried out to evaluate spatial variations in rice production areas by simulating rice growth and yield with CERES-Rice growth model under GCM $2{\times}CO_2$ climate change scenarios. A modified window version(v4.0) of CERES-Rice was used to simulate the growth and development of three varieties, representing early, medium, and late maturity classes. Simulated growth and yield data of the three cultivars under the climate for 1971 to 2000 was set as a reference. Compared with the current normal(1971 to 2000), heading period from transplanting to heading date decreased by 7~8 days for the climate in $2^{\circ}C$ increase over normal, and 16~18 days for the climate in UKMO with all maturity classes, while change of ripening period from heading to harvesting date was different with maturity classes. That is, physical maturity was shortened by 1~3 days for early maturity class and 14~18 days for late maturity class under different climate change scenarios. Rice yield was in general reduced by 4.5%, 8.2%, 9.9%, and 14.9% under the climate in $2^{\circ}C$, $3^{\circ}C$, $4^{\circ}C$, and about $5^{\circ}C$ increase, respectively. The yield reduction was due to increased high temperature-induced spikelet sterility and decreased growth period. The results show that predicted climate changes are expected to bring negative effects in rice production in Korea. So, it is required for introduction of new agricultural technologies to adapt to climate change, which are, for example, developing new cultivars, alternations of planting dates and management practices, and introducing irrigation systems, etc.