• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.141-143
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• 2012

The present study is aiming at numerically analyze the soot formation processes coupled with gas reaction mechanism in turbulent non-premixed and partially premixed flames. In order to realistically represent turbulence-chemistry interactions with detailed chemical kinetics and soot formation behaviour related to the turbulent non-premixed and partially premixed flames, the transient flamelet[1] and flamelet based level-set approach[2] are coupled with soot formation based on the two equation model [3] and DQMOM (Direct Quadrature Method of Moment)[4].

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.133-134
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• 2014

The full transport equation approach for laminar non-premixed flame with detailed chemistry, soot and radiation has an advantage in accuracy and describing for emission pathway, but this approach requires the excessive computational cost especially for a higher-order hydrocarbon fuel flames. On the other hand, the standard flamelet model has an efficiency and accuracy for non-premixed flame, though this model is not suitable for simulating slow processor like soot and radiation in laminar non-premixed flame situation. To overcome this limitation, modified transient flamelet model is developed which coupled with two-equation soot model involved in soot formation and evolution mechanism such as nucleation, surface growth, oxidation and agglomeration.

• 한국연소학회지
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• 제15권3호
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• pp.74-81
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• 2010

In this study, soot formation characteristics on the instability of laminar diffusion flames were investigated experimentally using a concentric co-flow burner. When a small amount of air was supplied through an inner nozzle, a stable propane laminar diffusion flame became unstable and began to oscillate mainly due to the dilution effect. The increase of air flow rate transformed an oscillating non-sooting flame into a stable nonsooting flame. When the air flow rate was continuously increased an inner flame was formed and the flame was changed to an oscillating sooting flame, an oscillating non-sooting flame and finally a stable non-sooting hollow flame. When the air flow rate was decreased, a non-sooting hollow flame was eventually changed back to a stable non-sooting flame. The presence of an inner flame, however, altered the soot formation characteristics of a flame. More soot production was observed with the presence of an inner flame. The increased or decreased soot formation/oxidation rates, the radiation heat loss, and the heating effect of inner flames are most likely to be responsible for the observed instability of laminar diffusion flames.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제48권6호
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• pp.371-381
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• 2022

Objectives: This study determined the effect of platelet-rich fibrin (PRF) on extraction socket bone regeneration and assessed the patterns and determinants of bone regeneration after the surgical extraction of impacted mandibular third molars. Materials and Methods: This prospective study randomly allocated 90 patients into two treatment groups: A PRF group (intervention group) and a non-PRF group (control group). After surgical extractions, the PRF group had PRF placed in the extraction socket and the socket was sutured, while the socket was only sutured in the non-PRF group. At postoperative weeks 1, 4, 8, and 12, periapical radiographs were obtained and HLImage software was used to determine the region of newly formed bone (RNFB) and the pattern of bone formation. The determinants of bone regeneration were assessed. Statistical significance was set at P<0.05. Results: The percentage RNFB (RNFB%) was not significantly higher in the PRF group when compared with the non-PRF group at postoperative weeks 1, 4, 8, and 12 (P=0.188, 0.155, 0.132, and 0.219, respectively). Within the non-PRF group, the middle third consistently exhibited the highest bone formation while the least amount of bone formation was consistently observed in the cervical third. In the PRF group, the middle third had the highest bone formation, while bone formation at the apical third was smaller compared to the cervical third at the 8th week with this difference widening at the 12th week. The sex of the patient, type of impaction, and duration of surgery was significantly associated with percentage bone formation (P=0.041, 0.043, and 0.018, respectively). Conclusion: Placement of PRF in extraction sockets increased socket bone regeneration. However, this finding was not statistically significant. The patient's sex, type of impaction, and duration of surgery significantly influenced the percentage of bone formation.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.139-140
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• 2012

In laminar non-premixed flame situation, the flamelet model is not suitable for simulating slow processor like soot and radiation. Thus in this study, we overcome this limitation by using the transient flamelet model. Also, for soot formation on laminar non-premixed flame, transient flamelet coupled with two-equation soot model has been adopted due to its inherent advantages in terms of accuracy and availability. Based on numerical results, the detailed discussion has been made for the precise structure and soot formation processes in the pressurized methane air flames.

• Restorative Dentistry and Endodontics
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• 제7권1호
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• pp.71-75
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• 1981

Five different labelled composite resin, Hypol (Korea), Glass-Ionomer (Japan), Simulate (U.S.A.), Durafil (U.S.A.) and Microfil (U.S.A.) were collected to employ for this experimental study. The purpose of the study is to determine the effect of finger pressure technic and traditional filling by means of plastic instruments on porosity formation in composite materials. Each material with pressure and non-pressure cases were carefully examined under electron microscope. Following were the results obtained through the study. 1. Pressured cases showed smaller number of porosity and the size of porosity was significantly smaller than non-pressured cases in each mateial. 2. Glass-Ionomer with pressure cases were seen as tube-like appearance because of pressured small porosities communicate in a certain direction. 3. Durafil cases both pressured and non pressured, appeared the least porosity formation. among the materiats. 4. Border line between the outmost periphery of the porosity and matrix of the resin in both pressured or non-pressured eases were found characteristically clear in Mierofil cases.

• 천문학논총
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• 제2권1호
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• pp.21-29
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• 1985

Two theories, the adiabatic and the isothermal, of galaxy formation are surveyed with regard to the current observational constraints, Some advantage of non-baryonic theory compared with the usual baryonic theory is discussed.

• 대한치과보철학회지
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• 제46권4호
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• pp.335-342
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• 2008

연구목적: 난소 절제술을 시행하여 골다공증을 재연한 쥐의 두개 결함부에 골 이식시 정상 쥐와 어떠한 골 재생 능력 차이를 보이는지 비교하고자 한다. 연구재료 및 방법: 20마리의 쥐를 2 그룹으로 각 10마리씩 나눈다. 그 중 10마리만 난소 절제술을 시행하고 7주 후 20마리 모두 두개골에 8 mm 직경의 임계 크기의 결함을 형성한 후 $OSTEON^{TM}$을 이식한다. 그 후 4주 후 모두 희생하여 조직학적 조각을 형성하여 방사선학적 및 조직형태학적 분석을 시행한다. 결과: Ovariectomy & $OSTEON^{TM}$군과 Non-Ovariectomy & $OSTEON^{TM}$군과의 신생골 형성 넓이의 효과 검증 결과, Ovariectomy & $OSTEON^{TM}$군은 평균 넓이는 19660.93 ${\pm}$ 17207.68 ${\mu}m$으로 Non-Ovariectomy & $OSTEON^{TM}$군의 69793.57 ${\pm}$ 33227.17 ${\mu}m$에 비해 적어진 것으로 나타났으며, 이러한 차이는 통계적으로도 유의한 것으로 나타났다 (t = -4.237, P < .01). 따라서 Ovariectomy & $OSTEON^{TM}$군의 new bone formation 넓이가 Non-Ovariectomy & $OSTEON^{TM}$군에 비해 작아진 것을 알 수 있다. Ovariectomy & $OSTEON^{TM}$ 군과 Non-Ovariectomy & $OSTEON^{TM}$ 군과의 알칼리 포스파타아제의 효과 검증 결과, Ovariectomy & $OSTEON^{TM}$군은 ALP는 평균 163.90 ${\pm}$ 61.44 IU/L으로 Non-Ovariectomy & $OSTEON^{TM}$군의 58.40 ${\pm}$ 18.30 IU/L에 비해 크게 높아진 것으로 나타났으며, 이러한 차이는 통계적으로도 유의한 것으로 나타났다 (t = 5.204, P < .001). 따라서 Ovariectomy & $OSTEON^{TM}$군의 ALP 수치가 Non-Ovariectomy & $OSTEON^{TM}$군 ALP 수치보다 높아진 것을 알 수 있다. 결론: 본 실험을 통해 골다공증이 유발되면 골 재생능력이 감소한다는 것을 결론지을 수 있다.

• Journal of Microbiology and Biotechnology
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• 제27권11호
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• pp.1942-1951
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• 2017

Campylobacter jejuni and Campylobacter coli are important foodborne pathogenic bacteria, particularly in poultry meat. In this study, the presence of extracellular DNase activity was investigated for biofilm-deficient Campylobacter strains versus biofilm-forming Campylobacter strains isolated from chickens, to understand the relationship between extracellular DNase activity and biofilm formation. A biofilm-forming reference strain, C. jejuni NCTC11168, was co-incubated with biofilm non-forming strains isolated from raw chickens or their supernatants. The biofilm non-forming strains or supernatants significantly prohibited the biofilm formation of C. jejuni NCTC11168. In addition, the strains degraded pre-formed biofilms of C. jejuni NCTC11168. Degradation of C. jejuni NCTC11168 biofilm was confirmed after treatment with the supernatant of the biofilm non-forming strain 2-1 by confocal laser scanning microscopy. Quantitative analysis of the biofilm matrix revealed reduction of extracellular DNA (16%) and proteins (8.7%) after treatment. Whereas the biofilm-forming strains C. jejuni Y23-5 and C. coli 34-3 isolated from raw chickens and the C. jejuni NCTC11168 reference strain showed no extracellular DNase activity against their own genomic DNA, most biofilm non-forming strains tested, including C. jejuni 2-1, C. coli 34-1, and C. jejuni 63-1, exhibited obvious extracellular DNase activities against their own or 11168 genomic DNA, except for one biofilm non-former, C. jejuni 22-1. Our results suggest that extracellular DNase activity is a common feature suppressing biofilm formation among biofilm non-forming C. jejuni or C. coli strains of chicken origin.

• Journal of Contemporary Eastern Asia
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• 제15권2호
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• pp.111-144
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• 2016

Alternate members of the Chinese Communist Central Committee are often overlooked regarding elite formation or even when assessing Chinese elites in general. This article focuses on the case of alternate members of the Central Committee from 1992 to 2007 in order to understand why some individuals will eventually be promoted and why some will never be. Through extensive quantitative testing, I argue that these non-promoted individuals differ from their counterparts in many ways, most of which can possibly be traced back to the type of formation they received early on. As such, the article concludes that Party School attendance and the age factor, through threshold analysis, are a significant factor helping us understand the difference between promoted and non-promoted houbu.