• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.447-452
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• 2001

Quenching phenomena of hemispherical downward facing convex surfaces with narrow gaps have been investigated experimentally. Experiments employed test sections having 1 and 2 mm in gap thickness and 1 atm in system pressure. From interpretations of the temperature and the heat flux history, it was found that the flooding inside the gap was restricted by CCFL phenomena and quenching process was propagated from lower to upper region of the internal copper shell. The ratio of the maximum heat fluxes at 1 mm to 2mm in gap thickness was the almost same that obtained by steady state experiments. The quenching scenario of the hemispherical downward facing surface with narrow gap has been suggested.

• Gut and Liver
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• 제12권6호
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• pp.609-610
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• 2018

• 유기물자원화
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• 제20권1호
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• pp.41-49
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• 2012

이형반응기 미생물연료전지(MFC) 시스템의 전기생산에 미치는 운전온도 및 전극간 거리의 영향에 관한 실험실 규모 실험을 수행하였다. 외부저항이 $(100\;{\Omega})$인 조건에서 시스템의 평균온도가 $30^{\circ}C$에서 $34^{\circ}C$로 증가할 때 외부저항 양단의 전압은 약 1.4배 증가하였다. 운전온도의 증가는 MFC의 OCV(open circuit voltage)를 증가시키며, 전극간 거리가 감소하고 운전온도가 증가함에 의해 최대전력이 얻어지는 전류가 상승하는 것으로 나타났다. MFC 시스템의 운전온도 증가에 의해 모든 전극간 거리조건에서 최대전력밀도가 크게 증가하였다. 시스템의 평균온도가 $4^{\circ}C$로 증가할 때 5~10 cm의 전극간 거리에서 얻어지는 최대전력밀도는 1.9~2.4배 증가하였고 동일한 온도조건에서는 전극간 거리가 감소할수록 전력수율이 증가하였다. MFC의 전기생산에 미치는 운전온도와 전극간 거리의 영향은 시스템의 내부저항과 밀접하게 관련되어 있는 것으로 나타났다. 즉, MFC의 운전온도가 증가하고 전극간 거리가 감소함에 의해 시스템의 내부저항이 감소함으로써 전기생산이 증가하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2259-2261
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• 1999

In this paper, an ozonizer, which can generate individual and superposed silent discharge, using three-phase voltage has been designed and manufactured. The ozonizer consists of 3 electrodes(Central Electrode, Internal Electrode and External Electrode) and 2 gaps(gap between Central Electrode and Internal Electrode, gap between Internal Electrode and External Electrode). Ozone is generated according to voltage supplying method to each electrode by individual silent discharge and three-phase superposed discharge. The characteristics of ozone generation were investigated with variation of discharge power and the quantity of supplied gas($O_2$). In case of individual silent discharge, the maximum values of ozone concentration, ozone generation and ozone yield were obtained between internal electrode and external electrode, and its values were 2300[ppm], 570[mg/h] and 745[g/kWh] respectively. Each maximum values was 5039[ppm], 1773[mg/h] and 851[g/kWh] respectively, when three-phase superposed silent discharge was employed. Therefore, characteristics of ozone generation with three-phase voltage are improved compared with single-phase voltage because silent discharge is generated continuously.

• 대한치과기공학회지
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• 제42권2호
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• pp.81-89
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• 2020

Purpose: This in vitro study was conducted to evaluate the marginal and internal fit of three-unit Co-Cr frameworks fabricated by computer-aided metal milling and direct metal laser sintering(DMLS) systems in comparison to conventional casting method. Methods: Three-unit Co-Cr frameworks were fabricated by conventional wax up with casting(CWC), computer-aided metal milling(MM) and direct metal laser sintering(DMLS)(n=10 each). The marginal and internal fit of specimens were examined using a light-body silicone impression material. The thickness of light-body silicone was measured at eight reference points each, divided in the mesio distal and bucco lingual directions. All measurements were conducted by a stereomicroscope. Digital photos were taken at 150× magnification and then analyzed using a measurement software. The Kruskal-Wallis test and Bonferroni correction were used for analyzing the results. Results: The mean(SD) is ㎛ for fabrication methods, the mean marginal fit were recorded respectively, DMLS 39(27), followed by CWC 63(38), MM 220(128). and the mean internal fit CWC 95(47), DMLS 116(49), MM 210(152). In addition, the largest gap was found in the occlusal surface area among the internal measurement areas of all groups. Conclusion: As a result, the direct metal laser sintering method showed better marginal and internal fit than the metal milling method. The marginal and internal fit were statistically different according to the three fabrication methods(p<0.001). Except the MM group, the marginal fit of the CWC and DMLS groups was below the clinical standard of 120 ㎛. Based on the results of this study, it can be applied to clinical use in the future.

• 대한치과보철학회지
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• 제43권5호
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• pp.611-621
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• 2005

State of problem: Zirconia all-ceramic restoration fabricated with CAM system is on an increasing trend in dentistry. However, evaluation of the marginal and internal fits of zirconia bridge seldomly have been reported. Purpose: This study was to evaluate the at of margin and internal surface in posterior 3-unit zirconia bridge framework fabricated with CAM system(DeguDent, Germany). Material and Method: Preparations of secondary premolar and secondary molar on artificial resin model were performed for fabrication of 3-unit posterior bridge framework. Fits of 5 zirconia bridge framework were compared with 5 precious ceramo-metal alloy framework(V-GnathosPlus, Metalor, Switzerland), and prepared margins were designed to chamfer and shoulder finishing line. Each framework was cemented to epoxy resin model with reinforced glass ionomer(FujiCEM, GC Co., Japan), embedded in acrylic resin and sectioned in two planes, mesio-distal and buccolingual. Samples were divided into six pieces by sectioning and had two pieces of each surface(i.e mesial, distal, buccal and lingual surface) per abutment, so there were eight measuring points in each abutment. External gap was measured at the margin and internal gaps were measured at the margin, axial and occlusal surface. Gaps were observed under the measuring microscope(Compact measuring microscope STM5; Olympus, Japan) at a magnification of $\times100$. T-test were used to determine the statistic significance of the different gaps between zirconia and metal framework. Results and Conclusion: 1. External and internal marginal gaps of zirconia and metal framework were in clinically acceptable range. External marginal gaps were not different significantly between zirconia$(81.9{\mu}m)$ and metal $(81.3{\mu}m)$ framework and internal marginal gaps of zirconia $(44.6{\mu}m)$ were smaller than those of metal framework $(58.6{\mu}m)$. 2. Internal axial gaps of zirconia framework$(96.7{\mu}m)$ were larger than those of metal frame-work$(78.1{\mu}m)$ significantly and adversely, internal occlusal gaps of zirconia frame-work$(89.4{\mu}m)$ were smaller than those of metal framework $(104.9{\mu}m)$ significantly. 3. There were no significant differences in external and internal marginal gaps between chamfer and shoulder finish line when zirconia frameworks were fabricated.

• The Journal of Advanced Prosthodontics
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• 제8권6호
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• pp.439-448
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• 2016

PURPOSE. The purposes of this study are to evaluate the internal and marginal adaptation of two widely used CAD/CAM systems and to study the effect of porcelain press veneering process on the prosthesis adaptation. MATERIALS AND METHODS. Molar of a lower jaw typodont resin model was prepared by adjusting a 1.0 mm circumferential chamfer, an occlusal reduction of 2.0 mm, and a $5^{\circ}$ convergence angle and was duplicated as an abrasion-resistant master die. The monolithic crowns and copings were fabricated with two different CAD/CAM system-Ceramil and Zirkonzahn systems. Two kinds of non-destructive analysis methods are used in this study. First, weight technique was used to determine the overall fitting accuracy. And, to evaluate internal and marginal fit of specific part, replica technique procedures were performed. RESULTS. The silicone weight for the cement space of monolithic crowns and copings manufactured with Ceramil system was significantly higher than that from Zirkonzahn system. This gap might cause the differences in the silicone weight because the prostheses were manufactured according to the recommendation of each system. Marginal discrepancies of copings made with Ceramil system were between 106 and $117{\mu}m$ and those from Zirkonzahn system were between 111 and $115{\mu}m$. Marginal discrepancies of copings made with Ceramil system were between 101 and $131{\mu}m$ and those from Zirkonzahn system were between 116 and $131{\mu}m$. CONCLUSION. Marginal discrepancy was relatively lower in Ceramil system and internal gap was smaller in Zirkonzahn system. There were significant differences in the internal gap of monolithic crown and coping among the 2 CAD/CAM systems. Marginal discrepancy produced from the 2 CAD/CAM systems were within a reported clinically acceptable range of marginal discrepancy.

• 대한치과보철학회지
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• 제54권3호
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• pp.210-217
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• 2016

목적: 본 연구의 목적은 실제 환자에서 디지털 구강스캐너로 모형 없이 제작한 보철물의 변연 및 내면 적합도를 평가하는 것이다. 대상 및 방법: 전향적 임상시험으로 시행한 본 예비 연구는 총 11개의 수복물을 대상으로 하였다. 구강스캐너(TRIOS, 3shape, Copenhagen, Denmark)로 디지털 구강인상을 채득한 후, 캐드 디자인 및 밀링 가공 과정을 통해 전부지르코니아 수복물을 제작하였다. 완성된 지르코니아관을 환자 구강 내에 시적하였고, 레플리카 술식으로 보철물-지대치 복제물을 얻었다. 이를 근원심, 협설 방향으로 잘라 변연오차, 변연간극과 축벽부, 선각부, 교합면부의 내면간극을 측정하였다. 통계처리는 Kruskal-Wallis 검정과 Mann-Whitney U 검정을 이용하여 통계적 유의성을 분석하였다(${\alpha}=.05$). 결과: 복제물을 통한 적합도 분석 결과, 근원심, 협설 절편 사이에는 통계적으로 유의한 차이가 없었다(P>.05). 변연간극에 불일치가 있었으며, 변연 오차가 변연간극 보다 컸다(P<.01). 결론: 본 연구의 한계 내에서, 구강스캐너로 모형 없이 제작한 전부지르코니아 수복물의 적합도는 임상적으로 허용할만한 결과를 보였다. 그러나 지르코니아관의 변연부위가 과풍융되는 경향이 있었으므로 주의 깊은 임상 적용 및 추적 연구가 요구된다.

• Journal of Gastric Cancer
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• 제20권4호
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• pp.408-420
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• 2020

Purpose: Isoform 2 of tight junction protein claudin-18 (CLDN18.2) is a potential target for gastric cancer treatment. A treatment targeting CLDN18.2 has shown promising results in gastric cancer. We investigated the clinical significance of CLDN18.2 and other cell-adherens junction molecules (Rho GTPase-activating protein [RhoGAP] and E-cadherin) in metastatic diffuse-type gastric cancer (mDGC). Materials and Methods: We evaluated CLDN18.2, RhoGAP, and E-cadherin expression using two-plex immunofluorescence and quantitative data analysis of H-scores of 77 consecutive mDGC patients who received first-line platinum-based chemotherapy between March 2015 and February 2017. Results: CLDN18.2 and E-cadherin expression was significantly lower in patients with peritoneal metastasis (PM) than those without PM at the time of diagnosis (P=0.010 and 0.013, respectively), whereas it was significantly higher in patients who never developed PM from diagnosis to death than in those who did (P=0.001 and 0.003, respectively). Meanwhile, CLDN18.2 and E-cadherin expression levels were significantly higher in patients with bone metastasis than in those without bone metastasis (P=0.010 and 0.001, respectively). Moreover, we identified a positive correlation between the expression of CLDN18.2 and E-cadherin (P<0.001), RhoGAP and CLDN18.2 (P=0.004), and RhoGAP and E-cadherin (P=0.001). Conversely, CLDN18.2, RhoGAP, and E-cadherin expression was not associated with chemotherapy response and survival. Conclusions: CLDN18.2 expression was reduced in patients with PM but significantly intact in those with bone metastasis. Furthermore, CLDN18.2 expression was positively correlated with other adherens junction molecules, which is clinically associated with mDGC and PM pathogenesis.

• 생명과학회지
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• 제10권6호
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• pp.630-639
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• 2000

The gastric pathogen Helicobacter pylori(H. pylori) establishes long-term chronic infection that can lead to atrophic gastritis, intestinal metaplasia, and gastric cancer. H. pylori, which express cytotoxic genes is now recohnized as a cause of peptic ulcer and is also a major risk factor for the development of gastric adenocarcinoma. We performed this study 1) to assess the detection rate of H. pylori according to direct investigation of bacteria of gastric biopsy specimen and two serologic tests of GAP test and Helico blot 2.0 system in the symptomatic and non-symptomatic group 2) to evaluate and compare the efficacy of two serologic tests of GAP test and Helico blot 2.0 system for the diagnosis of H. pylori infection. Forty-nine patients were positive for H pylori infection based on direct investigation of bacteria by histology. The detection rates of H. pylori infection based on direct investigation of bacteria by histology. The detection rates of H. phlori were significantly lower in gastric cancer than in other gastroduodenal disease(p<0.05). The concordance of two serologic tests of GAP test and Helico blot 2.0 system is poor. There was no statistically significant difference between the expression rate of CagA and VacA in the symptomatic and non-symptomatic group. Although Helico blot 2.0 system may not displace GAP test, it was a very sensitive serologic test for the diagnosis of H. pylori infection and it was used to detect IgG antibodies to H. pylori-specific antigens, including CagA, VacA and the various urease subunit. Our data suggest that further investigation is needed to determine whether or not the serologic expression of cytotoxic gene may be clinical usefulness of diagnostic methods in the gastroduodenal disease.