• Journal of Food Hygiene and Safety
• /
• v.37 no.1
• /
• pp.15-20
• /
• 2022

The purpose of this study was to compare the conventional culture method, enzyme immune method and the PCR method using species-specific primer in the analysis on the Salmonella spp. found in domestically distributed pet foods. For the study, Salmonella spp. were detected from 175 samples. From the conventional culture method and the PCR method, two samples (jerky and corn gluten) were determined as positive. Also, from the enzyme immune method, one sample (corn gluten) was test-positive. The study revealed that application of the PCR method with species-specific primer allows better distinguishment between the species of the strain collected from the samples than the conventional culture method and/or the enzyme immune method.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.13 no.2
• /
• pp.106-111
• /
• 2008

Six standard methods for marine ecotoxicological tests were established(or applicated) using marine decomposer, primary producers and consumers. Development processes referred to the standard methods established by USEPA(United States Environmental Protection Agency), international organizations and European methods. However, the standard test species were selected among the domestic species generally found in the Korean waters and sediments. The test methods provide the culture/maintenance of test species, test methods, reproducibility and quality acceptance criteria etc. A total of nine test species were designated including bioluminescent bacteria(Vibrio fischeri), diatom(Skeletonema costatum), seaweed(Ulva pertusa), rotifer(Brachionus plicatilis), benthic copepod(Tigriopus japonicus), benthic amphipods(Mandibulophoxus mai, Monocorophium acherusicum), and fishes(Oryzias latipes, Paralichthys olivaceus). These test species represent the decomposer, primary producer and consumers in marine trophic system in Korean coastal ecosystems, and we recommend the "battery test" including at least one species from the each trophic level for marine ecotoxicological test.

• The Korean Journal of Pesticide Science
• /
• v.15 no.1
• /
• pp.55-60
• /
• 2011

To work out quality control methods of environmental-friendly organic materials (EFOMs), the reason and basis for EFOM-selection and farmer's favorite formulation type of EFOMs, etc were investigated on farmers who had been practicing environmental-friendly agriculture. EFOMs used were soil amendments, control agents of plant diseases and insect pests, plant growth promotion formulations, in turns. In EFOMs application time, 22.7% of farmers sprayed EFOMs without delay after they were bought, in other hand, 77.3% of farmers used EFOMs which had been bought and stored for some period. Microbial density on seventeen environmental-friendly microbial formulates (EFMFs) including microbial pesticides, a microbial fertilizer, and environmental-friendly organic materials was investigated at different storing temperature and shelf life. When the microbial density of EFMFs was investigated without delay after they were bought, all used microbial pesticides and a microbial fertilizer was confirmed to be optimal for the certified density but two of environmental-friendly organic materials was confirmed not to be optimal. When microbial density of 17 EFMFs were investigated after storing them for six months at $4^{\circ}C$, only one of 9 microbial pesticides was confirmed not to be optimal, the other hand four of seven environmental-friendly organic materials not to be optimal, which each of their microbial density was less than the certified density. Population dynamics of microbial agents was much more influenced in fluctuated temperature (room temperature) than in static temperature condition ($5^{\circ}C$ and $25^{\circ}C$). Shelf life of microbial agents according to microbial formulation type were high in granule type, liquid wettable type and liquid type in turns.

• Korean journal of food and cookery science
• /
• v.24 no.5
• /
• pp.636-644
• /
• 2008

The principal objective of this study was to assess the effects of hydrocolloids(xanthan gum, guar gum, sodium alginate, k-carrageenan, carboxy-methyl cellulose) on the suppression of retrogradation in the bread. The pasting properties of the doughs and the sensory properties were determined in the bread samples, to which xanthan gum, guar gum, sodium alginate, k-carrageenan, and CMC, were added at different ratios(0.2%, 0.6%, 1%). CMC and k-carrageenan with 0.6% level were selected for the further retrogradation studies. Changes in the firmness of the bread samples at room temperature for 15 days were assessed using a texture analyzer, and the type of retrogradation was calculated via the Avrami equation. The thermal properties of the samples were also determined via differential scanning calorimetry (DSC). The addition of hydrocolloids was shown to increase the viscosities of the doughs. Setback and breakdown viscosity were reduced significantly via the addition of CMC(0.6%, 1%), xanthan gum(1%), and k-carrageenan(1%). Sensory hardness was significantly increased when 1% hydrocolloids were added. Our textural analysis showed that the addition of CMC reduced the firmness of the bread, whereas k-carrageenan didn't. However, the retrogradation rate was reduced via the addition of k-carrageenan, as was also demonstrated in the results of our DSC analysis.

• Journal of Life Science
• /
• v.28 no.12
• /
• pp.1477-1488
• /
• 2018

This study investigated the muscles, intestines, and gonads of Sulculus diversicolor supertexta to examine the diversity of microbial communities within examples collected from the Jeju Coast. Using different media, initial pure isolation in MA, 1% BHIA, and 1% TSA indicated that the muscles, intestines, and gonads supported more communities, respectively. In analysis of relative similarity with 16s rRNA sequencing, 190 pure colonies were isolated, and further analysis with NBLAST identified 71 species, 39 genera, 25 families, and five phyla. Homogeny with the reference strain was 91-100%. Microbial communities in S. supertexta consisted of gamma and alpha Proteobacteria (48%), Actinobacteria (32.5%), Firmicutes (16.9%), Deinococcus-Thermus (1.3%), and Bacteroides (1.3%). In all tissue, Psychrobacter cibarius in Moraxellaceae was dominant. Alteromonadaceae, Enterobacteriaceae, Pasturellaceae, Moraxellaceae, Rhodobacteraceae, Geminicoccaceae, Dietziaceae, Intrasporangiaceae, Microbacteriaceae, Micrococcaceae, Micromonosporaceae, Streptomycetaceae, Aerococcaceae, Bacillaceae, Paenibacillaceae, Planococcaceae, and Staphylcoccaceae were commonly isolated across all tissues, and Flavobacteriaceae, Corynebacteriaceae, Yesiniaceae, Vibrionaceae, Hahellaceae, Pseudomonadaceae were also identified from the intestines. In microbial monitoring of four harmful bacteria, Streptomyces albus (96%) showed antibacterial activity against all four strains, and Agrococcus baldri (99%) and Psychrobacter nivimaris (99%) presented against E. Coli and E. aerogens. In addition, some strains with low homogeny were isolated and further experiments are therefore required, for example to refine the antimicrobial substances including new strain investigations. These additional experiments would aim to establish generic resources for the microbial communities in S. Supertexta and provide basic data for applied microbiological research.

• The Korean Journal of Rheology
• /
• v.11 no.2
• /
• pp.159-167
• /
• 1999

Sandwich injection molding is one of the remarkable polymer processes recently developed from conventional injection molding. But it is almost impossible to do theoretical investigation that we've researched it through numerical simulation. In this paper, numerical simulation on the study of sandwich injection molding is based on Finite Element Method and FAN/Control Volume method. In addition to conventional filling parameter that can confirm skin polymer melt front, new filling parameters have been introduced to confirm core polymer melt front advancement. These filling parameters are defined in each layer which is divided to solve temperature field along the thickness direction. One can notice different filling patterns resulted from the variation of material properties such as viscosities and power-law indexes, and processing conditions such as switch-over times and wall temperatures. It gives us a better understanding of the sandwich injection molding process. And we can recognize that it's the core polymer spatial distribution after the completion of filling that is the most important key point to use this process for industrial molding process.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.105.2-105.2
• /
• 2010

석탄의 직접 연소 대신 고온/고압의 조건에서 불완전연소 및 가스화 반응을 통하여 일산화탄소(CO)와 수소($H_2$)가 주성분인 합성가스를 제조하여 이용하는 석탄 가스화 기술은 현실적인 에너지원의 확보를 위한 방법인 동시에 이산화탄소를 저감할 수 있는 기술이라 할 수 있다. 따라서, 본 연구에서는 non-slagging 방식의 pilot급 분류층 석탄가스화기를 대상으로 고압 미분탄공급장치, 합성가스 냉각장치, 고온 집진장치 등을 연계하여 상용급 석탄가스기와 유사한 $1,300^{\circ}C$, 20 kg/$cm^2$의 운전조건에서 미분탄의 안정적인 공급을 통한 양질의 합성가스 제조 및 제조된 합성가스의 분기 공급특성 시험을 진행하였다. 그리고, 고압 미분탄공급장치는 공급호퍼에 저장된 미분탄을 고온/고압 조건으로 운전되는 석탄가스화기에 공급하기 위한 설비로서, 이러한 고압 미분탄공급장치를 이용한 기류수송 방식의 미분탄 공급 기술은 가스화기 설계 및 운전제어 기술과 더불어 석탄가스화기 시스템의 안정적 연속운전을 위한 가장 핵심적인 기술 중 하나라고 할 수 있다. 따라서, 본 연구에서는 아역청탄인 인도네시아 ABK탄을 대상으로 향후 dense phase 고압 기류수송을 목적으로 하는 고압 미분탄공급장치의 성능특성을 시험을 진행하였는데, 시험 결과 73 kg/h 조건에서 20 kg/$cm^2$의 가스화기에 대한 안정적인 미분탄 공급특성을 확인할 수 있었으며, 이러한 미분탄 공급 조건에서 CO 40～45%, $H_2$ 16~20%, $CO_2$ 5~8% 조성의 양질의 합성가스를 평균적으로 $230{\sim}50Nm^3/h$ 안정적으로 제조할 수 있었다.

• Restorative Dentistry and Endodontics
• /
• v.27 no.6
• /
• pp.600-611
• /
• 2002

본 연구의 목적은 클로로필린이 치주인대 세포 생활력에 미치는 영향을 평가하는데 있다. 치주인대 세포는 건강한 사람에서 발치한 소구치의 치주인대 조직으로부터 채취하여 배양하였다. 비교 기준을 설정하기 위하여, HBSS 내에서 $37^{\ circ}C$로 보관한 치주인대 세포수의 50%가 생존하는데 소요되는 시간을 MTT 분석법에 의해 측정하였다. 그 결과는 6시간이었다. HBSS에 클로로필린 10, 100, 500 nM이 각각 첨가된 3군의 실험 보존액과 F-medium, ViaSpan, Likorol 등 모두 6군의 실험 보존액을 96-well plate에 접종한 후, 치주인대 세포를 동일한 수로 분주하였다. 이를 6시간동안 보관한 후, 각 실험군 보존액에서의 세포 생활력을 MTT 분석법으로 측정하였다 또한, HBSS와 F-medium 및 클로로필린 500 nM이 첨가된 HBSS군의 세포들에 대해 유식세포 계측을 시행하여 각각의 세포주기를 분석하였다. 실험 결과, 클로로필린 500 nM이 첨가된 HBSS에서 보관한 세포들이 가장 높은 생활력을 나타내었으며, 클로로필린이 첨가되지 않은 HBSS에 비해서 유의하게 양호한 세포 생활력 유지 능력을 보였다. 클로로필린으로 처치한 세포들은 클로로필린의 농도가 커짐에 따라 세포 생활력이 증가하는 양상을 나타내었다. 유식세포 계측 결과, HBSS와 F-medium 및 클로로필린 500 nM이 첨가된 HBSS에서 보관한 세포의 77~80%가 G0-G1 단계의 세포 주기로 측정되어, 대부분의 세포들이 안정된 세포 대사 상태를 보이는 것으로 나타났다. 결론적으로, 클로로필린 처치는 치주인대 세포의 생활력 유지에 도움이 되는 것으로 사료된다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.312-317
• /
• 2006

지역규모의 기후변화 모의결과를 이용하여 금강유역 용담댐의 홍수기 치수안전도에 대한 민감도분석을 수행하였다. 기후변화 모의에 사용된 SNURCM(Seoul National University Regional Climate Model)은 미국 National Center for Atmospheric Research의 Community Climate System Model의 전지구모형을 기반으로 spectral nudging 기법을 사용한 공간해상도 30 km, 연직 21층의 지역기후모형이다. 기후변화 시나리오로는 SRES 'B1'이 사용되었으며 과거 control run에 대한 기후모의 정확도 분석을 통하여 SNURCM 기상자료를 관측치와 비교한 결과 면적강우량을 다소 과소추정하였고 이점을 감안하여 SNURCM의 일 모의결과에 보정 계수를 적용하였다. 하천유출량은 SSARR 모형을 이용하여 SNURCM 모의가 수행된 전체기간을 $1980{\sim}1999$년과 $2000{\sim}2019$년으로 20년씩 나누어 용담댐 일 유입량을 산정하여 통계분석을 실시하였고 과거와 미래 20년 동안을 비교하여 본 결과 (1) 유량의 평균보다는 분산이 미래 20년 동안 증가하여 가뭄과 홍수에 대한 위험도가 증가함을 알 수 있었고, (2) 특히 연최대유량 또한 미래 20년 동안 상당히 증가하여 홍수기 치수대책이 더욱 중요해질 것으로 판단되었다. 마지막으로 용담댐 운영은 범용 시스템분석 도구인 STELLA(System Thinking Experimental Learning Laboratory with Animation) 상에서 GUI로 구현하여 유입량 변화에 따른 용담댐 치수안전도 변화를 모의해 보았다. 용담댐의 홍수기 운영은 저수지 수위가 제한수위를 초과하기 시작하면 Rigid ROM 발효하여 방류량을 결정하도록 구성하였고, 무효방류(spill)가 일어나는 현상을 실패로 가정하여 이에 대한 신뢰도(reliability), 회복도(resiliency), 그리고 심도(vulnerability)를 치수안전도 지표로 계산하였다. 전체기간을 1980년${\sim}$1999년, 2000년${\sim}$2019년, 2000년${\sim}$2009년, 그리고 2010년${\sim}$2019년까지 총 4구간으로 나누어 결과를 도출하였으며 예상한 바와 같이 후반기 20년 동안에 세 가지 지표가 취약해 지는 것을 확인할 수 있었고, 특히 2000년부터 2009년까지 10년 동안에는 더욱 취약해짐을 확인할 수 있었다.

• Polymer(Korea)
• /
• v.25 no.5
• /
• pp.744-753
• /
• 2001

One of the most important factors which affect the impact strength of high impact polystyrene (HIPS) is the rubber-phase particle size and size distribution. In this study, HIPS was prepared from a batch reactor to observe the influence of reaction conditions such as rubber content, agitation speed and prepolymerization time on the particle size and size distribution. Measurements concerning the particle size distribution were conducted using a particle size analyzer. Due to swelling, the particle suspended in toluene increases in size with lower heat-treatment temperature and shorter heat-treatment time, while the particle in methyl ethyl ketone shows quite reasonable size without any effort of heat-treatment. As rubber content increases, the average particle size increases substantially, but the increase in agitation speed at lower rubber contents does not have much influence on the size. However, the polystyrene-phase particles occluded in rubber-phase become more uniform as agitation speed increases. Longer prepolymerization time produces rubber-phase particles with narrower particle size distribution.