• 한국치위생학회지
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• 제5권2호
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• pp.131-145
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• 2005

There are normal inhabitants doing medically useful functions in the body. There are many kinds of bacteria performing specific functions in the oral cavity. Two strains of lactic add bacteria were isolated from normal inhabitants of children's oral cavity, which inhibited the production of volatile sulfur compounds by anaerobic bacteria. The authors identified the isolates by 16S rDNA partial sequencing. 1. Two isolates were Gram-positive bacilli and produced hydrogen peroxide. 2. When Streptococcus mutans was cultured in the media, the mean weight of formed artificial plaque on the orthodontic wires was $124.4{\pm}30.4$ mg, whereas being reduced to $5.2{\pm}2.0$ mg and $10.6{\pm}6.6$ mg in the media cultured with Streptococcus mutans and each isolate, respectively(p<0.05). 3. The number of viable cells of Streptococcus mutans was $3.4{\times}10^9$ per ml in the cultured solution, whereas those of Streptococcus mutans in the combined culture with each of isolates were $4.6{\times}10^8$ and $2.4{\times}10^8$ per ml. 4. The optical density was 1.286 in the supernatant of Fusoacterium nucleatum after vortexing for 30 minutes, whereas in the supernatant of combined Fusoacterium nucleatum and each isolate, they were reduced to 0.628 and 00497, which the percentages of coaggregation between them were 2904% and 57.8%, respectively. 5. The optical density of Fusoacterium nucleatum precipitate was 1.794 in the culture media containing cysteine and $FeSO_4$ being reduced to 1.144 and 0.915 in the coaggregated precipitates of Fusoacterium nucleatum and each isolate. 6. The similarity values of 16S rDNA sequence between each of isolates and Lactobacillus salivarius subsp. salicinius were 99.60% and 99.73%, respectively, meaning that isolates were Lactobacillus salivarius subsp. salicinius. These results indicated that two strains isolated from children's saliva, which inhibited the formation of plaque and the production of volatile sulfur compounds, were identified as Lactobacillus salivarius subsp. salicinius.

• 한국화재소방학회논문지
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• 제24권2호
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• pp.82-88
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• 2010

본 연구에서는 자동차 내장재에 적용되고 있는 플라스틱 합성물질의 화재위험성을 알아보기 위하여 콘칼로리미터를 이용한 열방출특성, 연기밀도시험기를 이용한 연기발생특성 및 독성지수시험기를 이용한 유 독성을 측정하였다. 자동차 내장재를 구성하고 있는 주요 부위별로 3종류씩 총 12개의 시편을 준비하여 실험하였다. 콘칼로리미터 실험결과, PVC sheet 및 PVC leather가 약 2초의 가장 빠른 착화시간을 보였으며, 12개의 시편 중 8개의 시편이 10초 이내의 착화시간을 나타냈다. 최대열방출률은 232~635$kW/m^2$ 정도로서 나일론과 PE로 구성된 플로우매트가 $635kW/m^2$의 가장 큰 최대열방출률을 보였다. Rubber로 구성된 보조매트는 최대열방출률은 가장 낮았지만 총열방출은 가장 큰 값을 보였다. 연기밀도시험기 실험 결과, rubber로 구성된 보조매트는 약 924의 가장 큰 연기밀도값을 보였으며, 초기연기발생량을 확인할수 있는 VOF4값은 PVC leather로 구성된 시트가 가장 큰 값을 나타냈다. 독성지수시험기 실험결과, 대부분의 시편에서 이산화탄소의 치사농도를 초과하였고, PVC를 포함하고 있는 시편에서 염화수소 및 브롬화수소의 검출수치가 비교적 높게 나타났으며, 치사농도를 초과하였다. 13가지 특정가스의 치사농도와 발생농도를 이용한 독성지수는 PVC sheet가 상대적으로 가장 높은 것으로 나타났으며, 모든 시편의 독성지수 1을 초과하는 결과를 보였다.

• 대한원격탐사학회지
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• 제22권2호
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• pp.141-151
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• 2006

태양광을 광원으로 하고 천정방향을 포함한 다양한 고도각을 이용하는 자외선/가시광선영역에서의 흡수분광학이 최근에 지상용 대기원격 측정에 개발되어오고 있다. 이를 이용하여 지표부근에 존재하는 대기 미량 물질의 공간적 분포가 유추될 수 있다. 대기질 측정기술 중 하나인 MAX-DOAS (Multi-axis Differential Optical Absorption Spectroscopy) 기술은 광원으로서 태양산란광을 이용하고, 다양한 고도각에서 태양산란광을 기록하고 분석을 통하여 대기 중 미량 물질을 측정한다. 광주과학기술원 환경모니터링 신기술 연구센터에서 개발된 MAX-DOAS 시스템은 9004년 1월, 5월, 10월에 각각 도시대기, 화산플룸, 화력발전소 플룸의 측정에 적용되었다. 각각의 경우에 $SO_2,\;NO_2,\;BrO,\;O_4$를 정량분석하기 위하여 기록된 MAX-DOAS 스펙트럼은 자외선/가시광선 영역에서의 고유 흡수스펙트럼을 이용한 DOAS 기술을 이용하여 분석 되었다. 그 결과는 Slant Column Density (SCD)로 표현되었다. 플룸 측정의 경우에서는 플룸 속에 포함된 $NO_2,\;SO_2$의 공간적 분포를 파악하기 위하여 플룸의 진행방향과 수직적인 방향에서 MAX-DOAS 스캔이 이루어졌다. 이를 통하여 얻은 단면적을 토대로 $SO_2,\;NO_2$ 농도가 계산되었다. 화산플룸에서 $SO_2$는 580ppbv, 화력발전소 플룸에서 $NO_2$는 337ppbv, $SO_2$는 227ppbv 로 계산되었다.

• 대한소아치과학회지
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• 제32권2호
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• pp.344-356
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• 2005

우리 인체에는 의학적으로 유용한 기능을 가진 세균들이 정상적으로 존재하며 구강내에도 독특한 기능을 나타내는 세균들이 상재한다. 본 연구에서는 치아우식증이 없는 소아의 타액에서 분리한 유산균 2주가 Streptococcus mutans에 의한 인공치태 형성과 혐기성 세균에 의한 휘발성 유황화합물 생성을 억제하는 것을 확인하고, API 50 CHL medium kit를 이용한 생화학적 검사와 16S rDNA sequencing으로 동정하여 다음과 같은 결과를 얻었다. 1. 분리균주는 2주 모두 그람양성 간균으로 과산화수소를 생성하였다. 2. 인공치태의 무게는 Streptococcus mutans의 단독 배양시 $124.4{\pm}30.4mg$이었으나, 분리균주와 병합 배양시에는 각각 $5.2{\pm}2.0mg,\;10.6{\pm}6.6mg$으로 현저하게 감소하였다(p<0.05). 3. Streptococcus mutans의 생균수는 단독 배양시 ml당 $3.4{\times}10^9$이었으나, 분리균주와 병합 배양시에는 각각 ml당 $4.6{\times}10^8$과 $2.4{\times}10^8$으로 감소하였다. 4. Fusobacterium nucleatum을 30분간 진탕한 후 측정한 상청액의 흡광도는 1.286이었으나, Fusobacterium nucleatum과 분리균주를 병합으로 30분간 진탕한 후 측정한 상청액의 흡광도는 각각 0.628과 0.497로 감소하였으며, 상호 결합 정도는 29.4%와 57.8%이었다. 5. Fusobacterium nucleatum의 단독 배양시 cysteine과 $FeSO_4$를 첨가한 배지를 가한 후 측정한 침전물의 배지 흡광도는 1.794이었으나, 분리균주와 병합 배양시 측정한 침전물의 배지 흡광도는 각각 1.144와 0.915로 감소하였으며, Porphyromonas gingivalis 단독 배양시 침전물의 배지 흡광도는 1.932이었으나 분리균주와 병합 배양시에는 침전물의 배지 흡광도가 각각 1.170과 1.266으로 감소하였다. 6. 분리균주를 API 50 CHL medium kit로 탄수화물 발효검사를 시행한 결과, 분리균주 1주는 Lactobacillus salivarius로, 다른 분리균주는 Lactobacillus delbrueckii subsp. lactis로 동정되었다. 7 분리균주를 16S rDNA partial sequencing으로 동정한 결과, 2주 모두 Lactobacillus salivarius subsp. salicinius와 유전자 유사치가 99.60%, 99.73%를 보여 Lactobacillus salivarius subsp. salicinius로 동정되었다. 이상의 결과를 종합하면 치아우식증이 없는 소아의 타액에서 분리된 유산균 중 과산화수소를 분비하여 인공치태 형성과 휘발성 유황화합물 생성을 억제하는 분리균주는 Lactobacillus salivarius subsp. salicinius로 동정되었다.

• Journal of Nutrition and Health
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• 제33권1호
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• pp.5-12
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• 2000

The control of food intake is a complex phenomenon caused by interactions between central and peripheral control mechanisms. The hypothalamic and brain stem regions have been identified as centers for food intake and energy expenditure in animals and humans. Of these, the ventromedial and lateral hypothalamic areas are involved in the control of food intake. Also, large amounts of neurotransmitters known to be involved in feeding are present in the hippocampus. Paricularly, tryptophan hydroxylase(TPH), known as a factor in the control of food intake, is present in high levels in the paraventricular nucleus of the hypothalamus and the hippocampus. In this study, TPH expression levels in the hypothalamic and hippocampal regions of fasting, anorexia mutant, and control mice were compared using RT-PCR and immunohistochemical methods. Differences in body weight among the fasting, anorexia mutant, and control groups wire observed. No statistical significance was noted in the number of TPH-immunoactivity in the hypothalamic nuclei, but relatively higher populations of such fibers were observed in the fasting group : the control group yielded samples with an overall value of 170.3${\pm}$3.5 in terms of immunoreactivity-induced optical density, whereas the fasting group yielded a value of 168.3${\pm}$2.6, and the anorexia mutant group 171.3${\pm}$0.8(lower values represent higher immunoreactivity), In fasting mice, stained neuronal bodies were observed in the CA3 and dentate gyrus regions of the hippocampus, which was different from the hippocampal regions of the control and anorexia mutant mice. The RT-PCR procedures were performed using whole brains, precluding any statistically noticeable findings in relation to specific regions, although the fasting and anorexia mutant groups showed 123.3% and 102.9%, respectively, of the TPH mRNA level in the control. The overall results present evidences of the role of TPH in the decrease in food intake during fasting caused by exogenic factors and in genetically acquired anorexia. (Korean J Nutrition 33(1) : 5-12, 2000)

• 한국약용작물학회지
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• 제15권2호
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• pp.100-104
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• 2007

A protocol for the production of transgenic Panax ginseng C.A. Meyer was established via Agrobacterium tumefaciens-mediated genetic transformation of direct somatic embryos. A number of conditions related to the co-cultivation were tested with respect to maximizing transformation efficiency. The results showed that pH of the co-cultivation medium (5.7), the bacterial growth phase (optical density; $OD_{600}$ = 0.8), co-cultivation period (3 days), and acetosyringone concentration $(100\;{\mu}M)$ had positive effects on transformation. Selected plantlets were cultured on the medium at an elevated hygromycin level(30 mg/l). Integration of the transgenes into the P. ginseng nuclear genome was confirmed by PCR analysis using hpt primers and by Southern hybridization using hpt-specific probe. The transgenic plantlets were obtained after 3-month cultivation and did not show any detectable variation in morphology or growth characteristics compared to wild-type plants.

• 대한치과보철학회지
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• 제46권3호
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• pp.227-237
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• 2008

STATEMENT OF PROBLEM: Zirconium oxide can be a substitute to titanium as implant materials to solve the esthetic problems of dark color in the gingival portion of implant restorations. PURPOSE: This study was performed to define attachment and growth behavior of osteoblast- like cells cultured on grooved surfaces of zirconium oxide and evaluate the genetic effect of zirconium oxide surfaces using the reverse transcriptase-polymerase chain reaction (RT-PCR). MATERIAL AND METHODS: MC3T3-E1 cells were cultured on (1) commercially pure titanium discs with smooth surface (T group), (2) yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) with machined surface (ZS group), and (3) Y-TZP with $100{\mu}m$ grooves (ZG group). Cell proliferation activity was evaluated through MTT assay and cell morphology was examined by SEM. The mRNA expression of Runx2, alkaline phosphatase, osteocalcin, TGF-${\beta}1$, IGF-1, G3PDH in E1 cells were evaluated by RT-PCR. RESULTS: From the MTT assay, after 48 hours of adhesion of MC3T3-E1 cells, the mean optical density value of T group and ZG group significantly increased compared to the ZS group. SEM images of osteoblast-like cells showed that significantly more cells were observed to attach to the grooves and appeared to follow the direction of the grooves. After 24 hours of cell adhesion, more spreading and flattening of cells with active filopodia formation occurred. Results of RT-PCR suggest that T group, ZS group, and ZG group showed comparable osteoblast-specific gene expression after 24 hours of cell incubation. CONCLUSION: Surface topography and material of implants can play an important role in expression of osteoblast phenotype markers. Zirconia ceramic showed comparable biological responses of osteoblast-like cells with titanium during a short-time cell culture period. Also, grooves influence cell spreading and guide the cells to be aligned within surface grooves.

• 한국광학회지
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• 제5권3호
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• pp.386-393
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• 1994

XeCl 엑시머 레이저를 횡방향의 전자빔으로 여기하여 이의 출력특성을 조사하였다. 전자빔의 출력은 880kV, 21kA(70ns, FWHM)이며 전자빔의 전류밀도는 다이오드(A-K) 간격과 공진기 외부에 설치한 펄스자계코일(4.7kG)로 제어하였다. 레이저 매질에 주입되는 전자빔의 축적에너지는 35J(4기압)이다. 축적에너지는 Radcolor film의 감광면적과 압력상승법에 의해 측정한 가스매질의 상승압력으로부터 환산된 수치이며, 이 때의 여기체적은 $320cm^{3}$이었다. 레이저 가스의 혼합비율은 HCl/Xe/Ar=0.2/6.3/93.5%이고 총압력이 3기압일 때, 최대효율 1.7%를 얻었다. 이 때의 출력에너지, 특성에너지는 각각 0.52J, 1.7J/l이었다. 실험결과의 분석을 위해 컴퓨터 시뮬레이션코드를 완성하였다. 시뮬레이션 결과는 실험결과와 잘 부합하고 있음을 확인하였고 그 결과를 이용하여 XeCl의 형성채널, 완화채널, 308nm의 흡수채널을 이론적으로 설명하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.216-216
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• 1999

The usage of a stationary plasma thruster (SPT) ion source, invented previously for space application in Russia, in experiments with surface modifications and film deposition systems is reported here. Plasma in the SPT is formed and accelerated in electric discharge taking place in the crossed axial electric and radial magnetic fields. Brief description of the construction of specific model of SPT used in the experiments is presented. With gas flow rate 39ml/min, ion current distributions at several distances from the source are obtained. These was equal to 1~3 mA/$\textrm{cm}^2$ within an ion beam ejection angle of $\pm$20$^{\circ}$with discharge voltage 160V for Ar as a working gas. Such an extremely high ion current density allows us to obtain the Ti metal films with deposition rate of $\AA$/sec by sputtering of Ti target. It is shown a possibility of using of reactive gases in SPT (O2 and N2) along with high purity inert gases used for cathode to prevent the latter contamination. It is shown the SPT can be operated at the discharge and accelerating boltages up to 600V. The results of presented experiments show high promises of the SPT in sputtering and surface modification systems for deposition of oxide thin films on Si or polymer substrates for semiconductor devices, optical coatings and metal corrosion barrier layers. Also, we have been tried to establish in application of the modeling expertise gained in electric and ionic propulsion to permit numerical simulation of additional processing systems. In this mechanism, it will be compared with conventional DC sputtering for film microstructure, chemical composition and crystallographic considerations.

• 한국가축번식학회지
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• 제14권2호
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• pp.93-100
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• 1990

These experiments were carried out to investigate the effect of rabbit anti-bovine cumulus cell antibodies on in vitro maturation of bovine follicular oocytes. Antisera to bovine cumulus cell were produced Japanese Ginat rabbit by repeated immunization of intact or solubilized bovine cumulus cell and purified by ammonium sulfate precipitation and Sepharose CL-4B protein-A affinity chromatography. The bovine cumulus cell-specific antibodies were confirmed by indirect ELISA. The results obtained in these experiments were summarized as follows : 1. The titer of the antibodies to cumulus cell determined by indirect ELISA using intact or solubilized bovine cumulus cell coated plates was very high in both intact and solubilized cumulus cells. Namely, the optical density at 1:12,800 dilution of antibodies was still significantly higher than that of non-immunized control serum. 2. When the follicular oocytes were treated with antibody to intact cumulus cells, the maturation rate of cumulus compacted and removed oocytes was ranged 47.6 to 59.1%. These value is significantly lower(p<0.05) than that(78.8%) of follicular oocytes cultured without the antibody. 3. the maturation rate of cumulus compacted and removed oocytes treated with antibody to solubilized cumulus cells was ranged 46.7 to 59.1%, significantly lower(p<0.05) than that(82.1%) of ooyctes cultured in antibody free medium. From above mentioned results, it could be said that cumulus cells promote nuclear maturation of follicular oocytes and that the beneficial effect of cumulus cells to the oocyte maturation is inhibited by the action of antibody to cumulus cells.