• Korean Journal of Environment and Ecology
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• v.11 no.3
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• pp.290-309
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• 1997

To investigate the plant community structure in Gunpo Experimental Forest of Mt. Suri, Kyonggi-do, sixty-four plots were set up and surveyed. By DCA ordination technique, sixty-four plots were divided into seven groups. The dividing groups were * Pinus rigitaeda community, P. densiflora community, P. densiflora-Quercus mongolica community, Q. variabilis community, Q. aliena comunity, Q. serrata community, Carpinus laxiflora community. Though the successional trend of seven communities by DCA ordination technique and DBH class distribution analysis was not clearly inferred, * Pinus rigitaeda community and P. densiflora-Q: mongolica community seems to be trended from present state to Q. spp. community. P. densiflora community, Q. variabilis community, Q. aliena community and Q. serrata community seems to be maintained preaent state and C. laxiflora community will be maintainde stable state. Shannon's diversity was 0.7430~1.3025(unit area: 300m$^{2}$) and soil acidity was pH 4.16~5.13 in surveyed areas.

• Bulletin of the Korean Chemical Society
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• v.26 no.12
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• pp.1981-1985
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• 2005

Kinetic studies have been performed for alkaline hydrolysis of a series of [(methoxy)(p-substituted styryl)carbene]pentacarbonyl chromium(0) complexes ($(CO)_5$Cr=$C(OCH_3)CH=CHC_6H_4X$, X = p-$OCH_3$, p-$CH_3$, H, p-Cl, p-$NO_2$). Second-order rate constants $(k_{{OH}^-})$ for the alkaline hydrolysis in 50% acetonitrile-water(v/v) were determined spectrophotometrically at various temperatures. At a low pH region (pH < 7.5), the observed rate constant $(k_{obs})$ remained constant with a small value, while in a high pH region (pH > 9.5), $k_{obs}$ increases linearly with increasing the pH of the medium. The second-order rate constants $(k_{{OH}^-})$ increase as the substituent X changes from a strong electron donating group to a strong electron withdrawing group. The Hammett plot obtained for the alkaline hydrolysis is consisted of two intersecting straight lines. The nonlinear Hammett plot might be interpreted as a change in the rate-determining step. However, the fact that the corresponding Yukawa-Tsuno plot is linear with $\rho$ and r values of 0.71 and 1.14, respectively indicates that the nonlinear Hammett plot is not due to a change in the rate-determing step but is due to ground-state stabilization through resonance interaction. The positive $\rho$ value suggests that nucleophilic attack by $OH^-$ to form a tetrahedral addition intermediate is the rate-determining step. The large negative ${\Delta}S^\neq$ value determined in the present system is consistent with the proposed mechanism.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.27-32
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• 2004

With an objective of evolving quantitatively and qualitatively superior bivolitine silkworm hybrid of Bombyxmori L. for tropics with shorter larval duration without compromising on productivity traits, a breeding programme was initiated at this institute during 1997 by utilizing breeding resource material from the institutes Germplasm collection. The breed SD7 is characterized with plain larvae spinning white oval cocoons and SD12 is characterized by sex-limited larval markings spinning white dumb-bell cocoons. After fixation, these breeds along with other newly evolved breeds were subjected for hybrid evaluation in the laboratory. Based on the hybrid studies, the hybrid SD7${\times}$SD12 was selected and evaluated for one year comprising three major sea- sons (6 trials) of tropics viz., Pre-monsoon (characterized by high temperature, low humidity and without any rain fall), Monsoon (characterized by moderate temperature, heavy rain fall with high humidity) and post-monsoon season (characterized by low temperature and low humidity with frequent rain fall) to know the fluctuations in the larval duration. The evaluation studies indicated that the hybrid is having shorter larval duration with productive merits. The hybrid SD7${\times}$SD12 recorded survival percent of 92.74, shell weight of 46.7 cg, shell ratio % of 24.0 and filament length of 1,200 meters with a shorter larval duration of 24 hrs; when compared to productive hybrid CSR2${\times}$CSR5(control). The breeding methodologies and hybrids usefulness for tropics were discussed.

• The Korean Journal of Quaternary Research
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• v.14 no.1
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• pp.57-63
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• 2000

A simulation model was used to examine the effects of climate variation on the tree-ring structure of Larix leptolepis trees growing at a plantation plot in Worak National Park in central Korea. The model uses mathematical equations to simulate processes affecting cell(tracheid) size variations for individual rings using daily precipitation and temperature measurements. Limiting conditions are estimated from temperature, day length and a calculated water balance. The results indicate that the seasonal growth is mostly limited by the soil moisture content and precipitation income during April and May. The April-May temperature also inversely influences the growth by increasing water losses from soil. The global climate-change scenario which includes regional warming(increasing temperature in spring-summer periods) appears to decrease the duration of optimal growths. Consequently, the model estimated that Larix leptolepis would lose the total production of xylem by 25%.

• Food Science of Animal Resources
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• v.33 no.5
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• pp.565-571
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• 2013

An enzyme ${\beta}$-galactosidase or ${\beta}$-galactohydrolase [EC3.2.1.23], commonly called lactase, mediates galacto-oligosaccharide (GOS) synthesis under conditions of high substrate concentrations. Also, lactase hydrolyzes ${\beta}$($1{\rightarrow}4$) lactose into glucose and galactose, the latter is successively transferred to free lactose to make various oligosaccharides via transgalactosylation. GOS is non-digestible to human digestive enzymes and has been used as a functional prebiotics. Among the 24 lactic acid bacteria (LAB) strains used, Lactobacillus paracasei YSM0308 was selected based on its exhibition of the highest ${\beta}$-galactoside hydrolysis activity, and the crude lactase was prepared for examination of reaction conditions to affect the GOS synthesis. Lactase activity was measured with a spectrophotometer using ONPG (o-nitropheyl ${\beta}$-D-galactopyranoside) method. Lactase activity was not detected in the culture supernatant and was mostly present in the cell pellet after centrifugation. Activity of the crude lactase preparation ranges from102 to 1,053 units/mL, with the highest activity determined for L. paracasei YSM0308. Optimal conditions for GOS synthesis are as follows: concentration of whey powder, pH, temperature, and time were 30%, pH 6.5-7.0, $30^{\circ}C$, and 4 h, respectively. The final GOS concentration was 19.41% (w/v) by the crude YSM0308 lactase, which was obtained from strain YSM0308 grown in the 10% (w/v) reconstituted whey-based medium.

• International Journal of Industrial Entomology and Biomaterials
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• v.18 no.2
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• pp.97-103
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• 2009

Sericulturists in the vicinity of Bangalore city irrigate their mulberry gardens with Vrishabhavathy stream water, which is polluted with domestic and industrial wastes from the city. To investigate the effect of pollutants on silkworm crops, a detailed field survey was conducted to study the cocoon yield pattern of the crops raised on mulberry irrigated with wastewater as against irrigation by bore/open wells. The villages along the stream were grouped into five test batches at about a distance of $5{\sim}8$ km from each other. The seasonal yield data with relevant information were collected through questionnaires from 117 rearers using stream water and 35 rearers using bore/open wells, the latter serving as control group. The average yield for 100 layings was 46 to 57 kg in the control group whereas in test groups, it ranged between 34 to 51 kg in the first test group and 22 to 38 kg in the rest. The difference in yield was $9{\sim}19$ kg depending on the season between control and test batches. In summer, this difference was higher, with high co-efficient of variation in test groups ($33{\sim}52$%). Further, water, soil and leaf samples were collected from selected rearers and were analyzed for zinc, copper, iron, lead and nickel. Results indicated significantly higher contents of these metals in samples from gardens using wastewater when compared control samples. Significantly (p<0.05 & p<0.01)) higher levels of zinc ($24{\sim}122$ ppm) and iron ($208{\sim}683$ ppm) were noticed in mulberry leaves during summer followed by winter and rainy season. The significance of high content of heavy metals in mulberry leaves and cocoon yield pattern of this area in relation to the quality of irrigation water is discussed.

• Journal of Mushroom
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• v.14 no.4
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• pp.162-167
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• 2016

Lactic acid bacteria (LAB) producing phenyllactic acid (PLA), which is known as antimicrobial compound, was isolated from button mushroom bed and the isolated LAB was identified to Lactobacillus casei by 16 rRNA gene sequence analysis. Cell-free supernatant (CFS) from L. casei was assessed for both the capability to produce the antimicrobial compound PLA and the antifungal activity against three fungal pathogens (Rhizoctonia solani, Botrytis cinerea, and Collectotricum aculatum). PLA concentration was investigated to be 3.23 mM in CFS when L. casei was grown in MRS broth containing 5 mM phenylpyruvic acid as precursor for 16 h. Antifungal activity demonstrated that all fungal pathogens were sensitive to 5% CFS (v/v) of L. casei with average growth inhibitions ranging from 34.58% to 65.15% (p < 0.005), in which R. solani was the most sensitive to 65.15% and followed by C. aculatum, and B. cinerea. The minimum inhibitory concentration (MIC) for commercial PLA was also investigated to show the same trend in the range of 0.35 mg mL-1 (2.11 mM) to 0.7 mg mL-1 (4.21 mM) at pH 4.0. The inhibition ability of CFS against the pathogens were not affected by the heating or protease treatment. However, pH modification in CFS to 6.5 resulted in an extreme reduction in their antifungal activity. These results may indicate that antifungal activities in CFS was caused by acidic compounds like PLA or organic acids rather than protein or peptide molecules.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.572-572
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• 2013

본 연구에서는 Plasma damage-free 선형 대향 타겟 스퍼터(Linear Facing Target sputtering: LFTS) 시스템을 이용하여 성막시킨 GaN-LED의 투명전극용 Ga-doped ZnO (GZO) 박막의 특성을 연구하였다. LFTS 시스템을 이용한 GZO 성막 공정 중 LED소자의 플라즈마 노출에 의한 데미지를 최소화 하기 위해 일정한 타겟간 거리(Target-to-Target distance: 65 mm)에서 타겟과 기판간 거리(Target-to-Substrate distance)를 50 mm에서 120 mm로 변화시키며 GZO 투명 전극을 성막해 박막의 특성과 소자의 특성을 동시에 분석하였다. LFTS에서 플라즈마는 GZO 타겟 사이에 형성된 일방향의 자장에 의해 효과적으로 구속되기 때문에 기판과 타겟 거리를 최적화 할 경우 플라즈마 데미지를 최소화하며 GaN-LED의 제작이 가능하다. 기판과 타겟 사이의 거리가 120 mm에서 최적화된 200 nm 두께의 GZO 투명 전극은 DC 파워 250 W, 공정 압력 0.3 mTorr, Ar 20 sccm 실험 조건하에서 LED 소자 위해 성막되었으며, 이후 $600^{\circ}C$ 수소 분위기에서 1분간 급속 열처리하였고 면저항(37 Ohm/sq.)과 450 nm 파장에서의 투과도(83%)를 나타냄을 확인할 수 있었다. LED 소자와 타겟 사이의 거리가 50 mm에서 120 mm로 증가할수록 성막공정 중 LED 소자에 미치는 플라즈마 데미지의 감소로 인해 GaN-LED 소자의 turn on voltage가 8.2 V에서 3.4 V로 감소한 것을 확인하였으며, 또한 radiant intensity는 20 mA의 전류를 인가하였을 시 0.02 mW/sr에서 8 mW/sr로 400배 향상되었다. 이러한 소자 특성은 대향 타겟 스퍼터 시스템으로 성장시킨 GZO 투명전극이 LED 소자의 투명 전극 층(Transparent Conductive Layer: TCL)에 적용될 수 있음을 말해준다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.473-473
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• 2013

전자종이, 입을 수 있는 디스플레이, 플렉서블 터치 스크린, 투과성 면 등과 같은 차세대 플렉서블 투명 전자소자는 기계적으로 유연하고 광학적으로 투명하며 무게가 가벼운 특성을 지녀야 할 것으로 예상된다. 현재까지는Indium tin oxide (ITO), zinc tin oxide (ZTO), carbon nano tube (CNT)와 polyimide 계열의 물질들이flexible, wearable, and transparent electronics (FWTEs) 소자의 electrode, active channel, dielectric layers로 제안되어 활발히 연구되었다. 최근에는 높은 이동도(~200,000 cm2/Vs) 및 유연성(fracture strain of 30%), 투명도 (97.5% for monolayer)와 같은 특성을 갖는 그래핀에 대한 연구가 활발히 진행되고 있다. 그러나 그래핀을 차세대 플렉서블 투명 전자소자 구현에 적용하기 위해서는 플렉서블하고 투명한 절연체의 확보 및 그래핀의 진성(intrinsic) 특성 유지 등과 같은 문제점들을 해결해야 한다. 따라서, 본 연구팀에서는 그래핀 기반 플렉서블 투명 전자소자의 게이트 절연층으로 적합한 poly-4-vinylphenol/poly (melamineco-formaldehyde) (PVP/PMF) 물질을 제시하고 이에 대한 전기적 재료적 분석을 수행하였다. 특히 다양한 PVP와 PMF의 비율 및 가열(annealing 혹은 curing) 온도에서 형성된 PVP/PMF 층의 화학 및 전기적 특성을 FT-IR, I-V, 그리고 C-V 측정을 통해 확인하였다. PVP/PMF는 유기절연 물질의 하나로서 높은 유연성과 투명도를 갖고 있을 뿐만 아니라 그래핀에 적용 시 그래핀의 진성 특성을 확보할 수 있다. 이는 PVP/PMF에 존재하는 hydroxyl (-OH) 그룹과 그래핀 상에서 정공(hole)을 공급하는 것으로 알려져 있는 -OH 그룹들간의 cross-linking 메커니즘에 의한 것으로 예상된다. 마지막으로 최적화된 PVP/PMF (낮은 hysteresis 전압)를 게이트 절연층에 적용하여 polyethylene terephthalate (PET) 기판 및 연구원의 손가락 위에 95.8%의 투명도 및 0에 가까운 Dirac point를 갖는 그래핀 기반 플렉서블 투명 전자소자를 성공적으로 집적하였다.

• Reproductive and Developmental Biology
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• v.32 no.2
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• pp.81-87
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• 2008

Production of transgenic animals for studying specific gene has been limited due to a low efficiency, lack of skilled researchers and the need for expensive equipment. Currently, the boar spermatozoa as a vector to deliver exogenous DNA into the oocyte were used to improve the efficiency of transfection rate. In this study, we revealed that the optimal conditions for DNA uptake in spermatozoa by liposome were to 90 min of incubation, $17^{\circ}C$, $10^5$ spermatozoa, 4 ng/ml of exogenous DNA and 0.5% (v/v) liposome, without damage to fertility. In addition, the developmental rate to the blastocyst stage of embryo in control group was significantly higher than those embryos with exogenous DNA and liposome, whereas there were no significant differences in embryo development between the liposome and type of DNA. The transfection rates of embryo using treated spermatozoa with both liposome and circular DNA were higher than those using linear DNA. These findings raise the possibility thattreated spermatozoa with liposome/DNA complexes could be used in in vitro fertilization, and the exogenous DNA transferred into the oocytes. Taken together, we demonstrated that liposome a vector for the uptake of exogenous DNA in boar spermatozoa could improve the efficiency of sperm-mediated gene transfer in creating transgenic pig and the other domestic transgenic animals.