• Macromolecular Research
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• 제17권1호
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• pp.44-50
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• 2009

Rigid polyurethane foams (PUF)s were synthesized with environmentally friendly blowing agents such as a cyclopentane/distilled water (10.0/1.0, pphp) mixture and distilled water only for four different silicone surfactants having different silicone/polyether ratios. An attempt was made to reduce the thermal conductivities of the PUF samples by varying the concentration and the silicone/polyether ratio of the various silicone surfactants. The scanning electron microscopy (SEM) results indicated an optimum concentration of the silicone surfactant of about 1.5 to 2.5 phpp for various surfactants to reduce the cell size and lower the thermal conductivity. The silicone surfactant having a higher silicone/polymer ratio showed a smaller cell size and, therefore, demonstrated the lower thermal conductivity of the PUF samples. From the relation between the thermal conductivity and the cell size of the PUF samples, the smaller cell size improved the thermal insulation property of the rigid PUF for both the PUF samples blown by the cyclopentane/distilled water (10.0/1.0, pphp) mixture and distilled water only. If the blowing agent is fixed, then the cell size is an important factor to decrease the thermal conductivity of the PUF samples. These results indicated that rigid PUF samples having lower thermal conductivity can be obtained by choosing a silicone surfactant containing a higher silicone/polyether ratio, as well as an optimum content of the surfactant.

• Macromolecular Research
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• 제17권11호
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• pp.856-862
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• 2009

This study examined the effects of liquid and solid additives on the morphological, mechanical and thermal insulating properties of rigid polyurethane foams (PUFs). The PUFs synthesized with tetramethylsilane (TEMS) as a liquid-type additive showed a smaller average cell size and lower thermal conductivity than those with the aerosil 200 and clay 30B as solid-type additives. When TEMS was added, the average cell size of the PUF became more uniform and finer due to the reduced surface tension of the polymer solution, which increased the nucleation rate and number of bubbles produced and reduced cell size. The PUFs with TEMS showed the highest closed cell contents among the PUFs prepared using TEMS, aerosil 200 and clay 30B. This suggests that the insulation properties of PUF can be determined by both the size of the cell structure and the amount of closed cell contents in the system. The compression and flexural strengths of the PUF increased slightly when the aerosil 200, clay 30B and TEMS were added compared those of the neat PUF. The reaction profiles of the PUFs showed a similar gel and tack tree time with the reaction time among the PUFs synthesized with three different additives and neat PUF. This suggests that the nucleating additives used in this study do not affect the bubble growth of the chemical reaction, and the additives may act as nucleating agents during the formation of PUF. From the above results of the cell size, thermal conductivity, closed cell contents and reaction profile of the PUFs, liquid-type nucleating agent, such as TEMS, is more effective in decreasing the thermal conductivity of the PUF than solid-type nucleating agent, such as aerosil 200 and clay 30B.

• 아시안잔디학회지
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• 제20권2호
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• pp.175-190
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• 2006

미생물제재(mycoherbicide)라는 용어는 1970년대부터 사용되기 시작하였다. 하지만 미생물 제재에 대한 관심은 화학제재의 비용증가로 인해 최근 주목을 받게 되었다. 고전적인 생물학적방제재(Biological Control Agent, BCA)는 생태적으로 안전하다는 이유로 생태학적인 관점에서 관심을 끌고 있다. 반면, 현대적인 의미의 생물학적방제재는 인공적으로 배양이 가능하고, 또한 그 잡초방제 효과도 화학제초제와 같은 수준이 요구된다. 현재 미생물제재는 7개국에서 곰팡이로부터 만들어지는 26종이있다. 이들은 재배작물에는 안전한 기주특이성을 갖는다. 그러나 대부분의 약제전달체계는 살아있는 미생물을 활력을 유지한 상태로 장기간 보존할 수 있는 능력을 가지고 있어야 함에도 불구하고 대부분이 조건을 충족시키질 못하였다. 또한, 실험실 수준에서는 방제효과가 잘 나타나지만, 실무적으로 사용할 경우 사용년도 및 포장에 따라 방제효과의 발현성과 지속성이 다르게 나타났다. 이 밖에 미생물제재 사용시 습도, 이슬, 온도 및 이들 요인이 잡초방제에 미치는 효과에 대한 연구결과도 미비한 상태이다. 따라서 잡초방제효과가 뛰어난 미 생물제재를 선별해야한다. 선행된 연구에서 제안된 효과적인 미생물제재의 조건은 첫째, 인공 배양법으로 내구성이 있는 접종원(inoculum)의 대량 생산이 가능하고, 둘째, 유전적으로 안정하면서 기주 특이성이 있고, 셋째, 다양한 범위의 잡초방제효과 있어야 한다. 미생물제재의 생산과 보급은 잡초의 생물학적인 방제에 지대한 역할을 할 수 있다. 액상보다는 입상 형태의 미생물제재가 가벼워서 사용이 간편하며, 젤(gel) 타입의 미생물제재도 사용되는 것으로 알려져 있다.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2199-2202
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• 2013

• Bulletin of the Korean Chemical Society
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• 제25권9호
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• pp.1326-1330
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• 2004

Several new derivatives of oxazolidinone phosphonate, that are expected to show biological activity, were prepared efficiently by previously published methods. ${\gamma}$-Ketophosphonate 1 was synthesized using pentacovalent oxaphosphorane chemistry followed by reductive amination with aromatic amine of oxazolidinone 4. Biological activity of the synthetic compounds has been studied. One of the synthetic compounds showed promising result for us to pursue further studies.

• 미생물학회지
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• 제46권3호
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• pp.270-277
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• 2010

장류 제조에 Bacillus cereus의 오염을 줄이기 위한 방법으로 전국 150 종 장류에서 분리한 무독소 Bacillus subtilis 및 Bacillus licheniformis 균들을 대상으로 B. cereus에 대해 억제능력이 큰 한 균주 SCK 121057를 선발하였다. SCK 121057은 생화학 검사 및 16S rRNA 유전자 서열에 의한 계통도 분석 결과 B. licheniformis로 동정되었고 12 종의 B. cereus 이외에 중요 병원성 균인 Staphylococcus aureus, Aspergillus flavus, A. ochraceus, A. parasiticus 등의 증식을 억제하였다. SCK 121057이 생산하는 항균 물질은 고압멸균 조건에서 열안정성, proteinase K에 대한 가수 분해 저항성, $37^{\circ}C$에서 장기 저장성을 지닌 구조적으로 매우 안정한 물질이었고, 전자현미경 관찰에서 이 물질은 B. cereus의 세포막을 손상시켜 ghost cell을 형성하였다. SCK 121057 균과 B. cereus를 혼합 접종한 청국장 적용 실험 결과 B. cereus 균수는 대조군에 비해 극적으로 감소되었다.

• Journal of Microbiology and Biotechnology
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• 제15권4호
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• pp.701-709
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• 2005

An efficient method of selecting an antagonistic strain for use as a biological control agent strain was developed. In this improved method, the surface tension reduction potential of an isolate was included in the 'decision factor,' in addition to two other factors; the growth rate and pathogen inhibition. By using a statistically designed method, an isolate from the soil was selected and identified as Bacillus sp. GB 16. In the pot test, this strain showed the best performance among the isolated strains. The lowest disease incidence rate and fastest seed growth were observed when the Bacillus sp. GB 16 was used. The action of the surface tension reducing component was assumed to enhance the wetting, spreading, and residing of the antagonistic strain in the rhizosphere. This result showed that the improved selection method was quite effective in selecting the best antagonistic strain for the biological control of soilborne infectious plant pathogens.

• 한국미생물·생명공학회지
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• 제49권1호
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• pp.24-31
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• 2021

This study aimed to investigate the melanogenesis inhibitory activity of epicatechin-3-O-gallate (ECG) isolated from Polygonum amphibium L. ECG was isolated from the ethanol extract of P. amphibium L, and its chemical structure was determined using spectroscopic methods such as LC-ESI-MS, 1D-NMR, and UV spectroscopy. ECG inhibited the melanogenesis of B16F10 cells in a dose-dependent manner. Particularly, it decreased the melanin content by 27.4% at 200 µM concentration, compared with the control, in B16F10 cells, without causing cytotoxicity. It is noteworthy that the expression of three key proteins, including tyrosinase, tyrosinase-related protein-1 (TRP-1), TRP-2, and microphthalmia-associated transcription factor (MITF), involved in melanogenesis, is significantly inhibited by ECG. The ECG isolated in this study caused the inhibition of body pigmentation and tyrosinase activity in vivo in the zebrafish model. These results suggest that the ECG isolated from P. amphibium L. is an effective anti-melanogenesis agent.

• Journal of Korean Biological Nursing Science
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• 제15권4호
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• pp.202-209
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• 2013

Purpose: The purpose of this study is to investigate relationships among sun-screening agents use, bone health promotion behavior, and bone mineral density. Methods: The participants of this study were 105 female college students. The data were collected using a questionnaire about sun-screening agent use and bone health promotion behavior. Bone mineral density was measured with Ultrasound Bone Densitometer/Osteo Pro Series. Data were analyzed with the SPSS/Win 18.0 program. Results: The mean Z-score in female college students was $-1.04{\pm}1.26$, and the T-score was $-1.16{\pm}1.22$, 21.39% of the participants have osteopenia. Bone mineral density showed a significant correlation with weight. Bone mineral density showed no significant correlation between sun-screening agent use, and bone health promotion behavior. There was a significant correlation between protection power of sun-screening agents and the protection by clothes. Conclusion: According to the results of this study, we need to develop an intervention program for bone health promotion of female college students.

• 미생물학회지
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• 제50권1호
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• pp.84-86
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• 2014

길항균을 생물 농약으로 개발하기 위해서는 저렴한 산업용 배지를 이용한 대량 생산 체계를 확립하는 것이 중요하다. 본 연구에서는 풋마름병 방제 효과가 뛰어난 Bacillus amyloliquefaciens SKU-78 균주의 배양조건을 확립하였다. 저가의 산업용 기질로는 콩가루와 옥수수 전분 배지가 균 생장에 가장 효과적이었고, 최초 pH 5.5, 배양 온도 $30^{\circ}C$, 교반속도 150-250 rpm의 조건으로 30 L fermenter를 이용한 배양에서 20 시간째에 최대 생균수($1.2{\times}10^{11}$ CFU/ml)에 도달하였다. 저가의 산업용 배지로 배양한 배양액을 관주 처리하였을 때 65%의 발병 억제 효과를 나타냄으로써 SKU-78 균주의 산업용 배지를 이용한 대량배양의 기초가 마련되었다.