• Research in Plant Disease
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• v.8 no.4
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• pp.228-233
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• 2002

This experiment was carried out to investigate the primary inoculum of strawberry anthracnose in nursery field. The pathogen, Colletotrichum gloeosporioides was not detected in soil and weeds of nursery field but symptom of anthracnose was developed in mother plants collected from market after incubation in humid chamber, The symptom of anthracnose was expressed in the strawberry plant that reserved for 17 days in field after inoculation by spore suspension but was not observed there after. When inoculated leaves were observed by SEM, only appressoria were observed 7 days after inoculation. So, it is guessed that dissemination of Colletotrichum sp. into nursery held will be by contamination of mother plants, and diagnosis by naked eyes may be impossible because symptom will be not developed if environment is to be adequate to penetration and in case of imperfect penetration after germination, the pathogen remains appressorium to achieve penetration.

• Korean Journal of Environmental Agriculture
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• v.5 no.1
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• pp.67-72
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• 1986

The nitrofen adsorption on several clay minerals was determined by sludge method to know the effect of clay minerals on the nitrofen activity. The bioassay was conducted with wheat seedlings to study the influence of the adsorbed nitrofen on the nitrofen activity. It is apparant that a four hours shaking was enough to reach the equilibrium concentration. The more the amount of sample, the more nitrofen was adsorbed by clay minerals, whereas the more nitrofen adsorption per unit gram of sample was observed at a 200 mg addition than a 400 mg in the same nitrofen solution. A little amount of nitrofen was adsorbed on Ca-zeolite or Ca-kaolinte, and much more nitrofen was adsorbed on Na-montmorillonite than the other clay minerals in the experiment. Little effect of pH on the adsorption would be attributed to physical adsorption between nitrofen molecule and clay surface. Na-and Ca-montmorillonite were the most effective in reducing the phytotoxicity of nitrofen to the growth of wheat seedlings among clay minerals which nitrofen was added to the growth media.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.5
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• pp.315-320
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• 2006

A precision test of hydrometer method, used to determine soil texture, was conducted on selected 10 soil samples, compared to pipette method. Soil texture measurements with hydrometer method were performed with monitoring the temperature of soil suspension in settling cylinder. The temperature and its fluctuation during settling time had a range of $13^{\circ}C-28^{\circ}C$ and $0.2^{\circ}C-4.4^{\circ}C$, respectively. The difference of clay content between hydrometer and pipette method were distributed from -6.4% to 4.0%. Positive end of difference in clay content was observed at soil having very low clay content, whereas negative end at soil having high organic matter content and exchangeable cations. Except both ends, difference in clay content of soils was less than 3%, and expecially closed to 0% in soils having clay content more than 25%. The difference of sand content were distributed from -1.5% to 4.2%. Similar to clay content, positive end soil was soil sample having lowest sand content.

• The Korean Journal of Mycology
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• v.29 no.2
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• pp.116-122
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• 2001

An isolate of the prospective hyperparasite, Ampelomyces quisqualis 94013 (AQ94013) was selected for the use of biological control of cucumber powdery mildew caused by Sphaerotheca fuliginea. Examination for the parasitism processes by scanning electron microscopy and light microscopy showed that conidia of AQ49013 germinated on conidia, conidiophores and hyphae of Sphaerotheca fuliginea four hours after inoculation. Appressorium-like structures were developed and attached to the hyphae of S. fuliginea seventeen hours after inoculation. Hyphae of AQ94013 penetrated into hyphae of S. fuliginea twenty-four hours after inoculation. Pycnidia of AQ94013 were produced in the hyphae and the basal part of conidiophores of S. fuliginea fourty four hours after inoculation. The pycnidia of AQ94013 matured foully eight hours after inoculation, and the conidia were discharged from the ostioles of the pycnidia fifty two hours after the inoculation. At the same time, hyphae and conidiophores of S. fuliginea were distorted and died. Also, concentrated culture filtrate and culture filtrate of AQ94013 had not suppressed the cucumber powdery mildew fungus as water treatment. Therefore, mode of action of AQ94013 was assumed to be parasitism on powdery mildew fungi.

• Korean Journal Plant Pathology
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• v.3 no.3
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• pp.180-186
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• 1987

Cell suspensions of two isolates of Pseudomonas syringae. PS8401 from sweet persimon and PS8402 from tea plant, were active in ice nucleation at -2.5 and $-3.8^{\circ}C$, respectively. Ice nucleation at those temperature was, using micropipette method, detected in suspensions ($10^8$ olony forming unit/ml of distilled water) of cells that had been grown on nutrient agar supplemented with $2.5\%$ glycerol. Using the same method, on the other hand, the freezing temperature of distilled water only was approx. $-21.8^{\circ}C$, and those of various plant saps including corn were lower than $-11.6^{\circ}C$. Corn seedlings sprayed with cell suspensions $(10^8\;cfu/ml)$ of nutrient broth) of PS8401 began to be damaged at $-2^{\circ}C$ and were almost completely damaged at $-4^{\circ}C$, whereas seedlings sprayed with nutrient broth only were not injured until the temperature down to $-9^{\circ}C$. Amounts of frost damage measured 48 hr after application of PS8401 suspensions increased as applied bacterial cell densities were increased. Ice-nucleation activity of the cell suspensions in vitro increased with increasing the number of cells in suspension. The activity also affected by growth-medium composition or growth-temperature. Ice nucleation thus occured at -4.0, -4.4 and $-7.2^{\circ}C$ in suspensions $(10^2\;cfu/ml)$ of PS8401 that had been grown at$25\%$ nutrient agar with $2.5\%$ glycerol, nutrient agar with $2.5\%$ glucose and nutrient agar only, respectively, and occured at -4.0 and $-7.6^{\circ}C$ in suspensions $(10^2\;cfu/ml)$ of PS8401 hat had been grown on nutrient agar with $2.5\%$ glycerol at $15\~25^{\circ}C$ and $30^{\circ}C$, respectively.

• The Korean Journal of Malacology
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• v.12 no.2
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• pp.91-97
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• 1996

바윗굴의 산란유발 및 종묘생산을 위한 생물학적 기초자료를 얻고자 자극방법별 효과와 난발생 및 유생사육에 미치는 수온의 영향에 관하여 실험한 결과, 자극방법별 산란유발은 정자현탁액 첨가구에서 가장 많은 산란량과 높은 수정률을 나타냈고, 난발생 및 유생사육의 각 단계에 이르기까지의 수온(T, $^{\circ}C$)에 따른 발생속도(h, 시간)는 수온이 높을 수록 빨랐으며, 그 관계식은 다음과 같다. 담륜자기 :1/h= 0.0069T - 0.0950(r=0.9447)D형 유생 :1/h= 0.0006T - 0.0045(r=0.9288)초기 각정기 유생:1/h= 0.0002T - 0.0019(r=0.9358)후기 각정기 유생:1/h= 0.0002T - 0.0022(r=0.9868)부착기 유생:1/h= 0.0001T - 0.0013(r=0.9897)또한 바윗굴의 수온과 난발생 속도와의 관계에서 추정된 난발생의 생물학적 영도는 평균 10.96$^{\circ}C$였으며, 수온별 유생사육시 바윗굴의 생존율은 24$^{\circ}C$에서 6.8%로 가장 좋았다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1141-1151
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• 1998

An effective thermal conductivity measurement for suspensions of microparticles in oil mixture is conducted in order to evaluate the shear rate-dependence of the thermal conductivity of suspensions. Measurements are made for rotating Couette flows between two concentric cylinders. The rotating outer cylinder is immersed into a constant temperature water bath while the stationary inner cylinder is subject to a uniform heat fluff. Test fluids are made to be homogeneous suspensions, in which neutrally buoyant microparticles ($d=25{\sim}300{\mu}m$) are uniformly dispersed. The present measurements show strong shear-rate dependent thermal conductivities for the suspensions, which are higher than those at zero shear rate. The shear rate dependent thermal conductivity increases with the particle size and volume concentration.4 new model for shear rate-dependent thermal conductivity of microparticle suspensions is proposed; the correlation covers from zero shear rate value to asymptotic plateau value at moderately high shear rates.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.103-103
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• 2003

대기나 물에 용해된 여러 가지 유해한 유기물을 분해하기 위한 방안으로서 다양한 광촉매 재료를 이용하려는 시도가 진행되고 있다. 하지만 광촉매 반응은, 현탁액 내에서 submicrometer 크기를 갖는 반도체재료에서 발생하므로 처리된 폐수로부터 촉매를 제거해야 하는 정제공정 (downstream process)이 필요하며, 이는 경제적인 측면에서 큰 경비를 요구하게 된다. 이를 해결 하기 위하여, 가장 우수한 광촉매 재료로 평가받는 TiO$_2$를 glass beads, sands, silica gel등의 물질에 고정시키거나, TiO$_2$를 자성 입자에 코팅시킨 형태인, 자성 광촉매입자를 응용하려는 연구가 최근 활발하게 진행되고 있다. 따라서 본 연구에서는 광촉매의 고정화와 재활용 효율을 향상시키기 위하여 TiO$_2$ 나노입자를 y-Fe$_2$O$_3$ 나노입자의 표면에 코팅하여 나노입자의 큰 비표면적을 활용하고 미세구조를 제어하여 입자간의 고정특성과 자기적 특성의 제어기술을 확립하고자 하였다.

• Korean Journal Plant Pathology
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• v.12 no.3
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• pp.291-296
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• 1996

옥수수 유묘접종시 깜부기병이 가장 잘 발병하는 조건은 4엽기 옥수수묘를 10\ulcorner~10\ulcorner/ml 농도의 소생자 현탁액으로 경엽살포한 후 28~3$0^{\circ}C$의 습실상에서 24시간 둔 후 꺼내어 온실에 두었을 때였다. 유묘의 엽기가 이보다 어리거나 접종원 농도가 이보다 높을 때, 혹은 습실상내 처리기간이 길어지면 접종후 유묘의 이른 고사를 초래하였다. 또한 습실상의 온도가 낮아질수록 깜부기병의 발병정도도 감소하였다. 깜부기병의 발생은 소생자 현탁액의 경엽살포 및 줄기주사접종에 의해서는 가능하였지만 토양관주에 의해서는 발병하지 않았다. 소생자 현탁액은 별도의 영양원의 첨가 없이도 발병을 잘 유도하였다. 동포자 현탁액을 직접 경엽살포하거나 줄기주사접종하여도 발병하였으나 소생자 현탁액접종에 비하여 발병정도가 현저히 낮았다.

• Journal of the Korean Society of Visualization
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• v.11 no.3
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• pp.12-16
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• 2013

The impact and spreading behaviors of silicon dioxide nanoparticle colloidal suspension droplets were quantitatively visualized using a high-speed imaging system. Millimeter-scale droplets were generated by a syringe pump and a needle. Droplets of different velocity were impacted on a non-porous solid surface. Images were consecutively recorded using a CMOS high-speed camera at 5000 fps (frames per second) for millimeter-scale droplets. Temporal variations of droplet diameter, velocity and maximum spreading diameters were evaluated from the sequential images captured for each experimental condition. Effects of Reynolds number, Weber number, and particle concentration were investigated experimentally.