• 대한기계학회논문집A
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• 제40권1호
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• pp.73-79
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• 2016

차단기 메커니즘의 안전성은 클로징 메커니즘 작동 시 접점 이후의 속도 감소를 통한 오픈 샤프트가 래치에 걸리는 래칭(latching) 구간에서의 유지 시간 개선을 통해 확보된다. 이는 오픈 래치가 복귀할 시간을 확보하여 재 차단되는 현상을 줄이기 때문이다. 본 연구에서는 캠 윤곽 최적화를 통해 기존의 구동 성능을 만족하고 래칭 구간에 대한 메커니즘의 안전성을 확보하고자 가동부의 변위 응답 중 래칭이 발생하는 구간에서의 유지 시간을 개선하였다. ADAMS 를 이용한 차단기 다물체동역학 모델을 개발하였으며 시험 결과와 비교하여 검증하고 최적설계 프로그램인 PIAnO 를 사용하여 캠 윤곽의 최적설계를 수행하였다. 캠 윤곽의 최적설계는 캠의 반경 방향으로 설계점을 선정하였으며 설계구간별 민감도 분석을 수행하였다. 최적화 결과 래칭 구간에서의 유지 시간을 개선하였다.

• 구강회복응용과학지
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• 제22권2호
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• pp.111-123
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• 2006

A Study on the Fracture Strength of All-Ceramic Crown according to the Zirconia Coping Design using CAD/CAM System L. Bulgan, In-Ho Cho, Soo-Yeon Shin Department of Prosthodontics, Graduate School, Dankook University The fracture strength of prosthesis is important, because it affects the function, and long term success of prosthesis and teeth. The purpose of this study was to compare the fracture strength of zirconia coping designs. Experimental test group were classified into three designs according to coping design, Modified design: Zirconia coping margin was located at 1mm above the axiogingival line angle. Collarless design: The coping margin terminated at the axiogingival line angle Butt design: The coping margin was extended to the finishing line of prepared margin. A $Cercon^{(R)}$(Degussa, Germany) CAD/CAM system was used to make the zirconia coping. Fracture strength was measured using loading machine at a cross head speed of 1mm/min. The results were statistically analyzed using the one-way ANOVA and multiple comparison test. Statistical significance was set in advance at the probability level of less than 0.05. The result : I. Collarless($738N{\pm}155N$) and Modified($755N{\pm}185N$) groups showed significantly a lower fracture strength than Butt($1057N{\pm}262N$) group(p<0.05). II. There were no statistical differences of the fracture strength between Modified($755N{\pm}185N$) and Collarless($738N{\pm}155N$) groups. III. When comparing the fractured surface, all the group showed porcelain fracture, which were fractured at the labial surface of baked porcelain The butt design of the zirconia coping has higher fracture strength than modified and collarless design.

• Journal of Astronomy and Space Sciences
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• 제19권3호
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• pp.187-196
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• 2002

2000년 11월부터 2001년 5월까지 총 16일간 맥동 식쌍성 Y Carn을 소백산천문대의 61cm 망원경에 부착된 단일 V 필터로 CCD 측광을 수행하였다. 새롭게 얻은 V 광도곡선과 Broglia & Marin(1974)의 BV 광도곡선을 Wilson-Devinney 방법의 Mode 2(분리형)와 Mode 5(준분리형)으로 분석하였다. 분석 결과는 다음과 같다. 1) 광도곡선 분석만으로는 분리헝과 준분리형의 Roche 모형 중 어느 것이 Y Cam의 진실한 Roche 모형인가를 가려낼 수가 없다. 2) Y Cam의 B광도곡선에는 삼체의 광도가 약 2%, V광도곡선에는 약 3% 존재한다. 3) Y Cam의 주성에서 발생하는 맥동에 의한 밝기 변화는 광도곡선 해에 거의 영향을 주지 않으나, 맥동을 고려하였을 경우 분리형 모델이 준분리형 모델보다 약간 더 관측치를 잘 맞춘다. 4) 분리형과 준분리형 각각에 대해 Y Cam의 절대물리량을 계산하였다.

• Restorative Dentistry and Endodontics
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• 제42권1호
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• pp.9-18
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• 2017

Objectives: This study evaluated color differences (${\Delta}Es$) and translucency parameter changes (${\Delta}TPs$) of various computer-aided design/computer-aided manufacturing (CAD/CAM) blocks after immersion in coffee. Materials and Methods: Eight CAD/CAM blocks and four restorative composite resins were evaluated. The CIE $L^{\ast}a^{\ast}b^{\ast}$ values of 2.0 mm thick disk-shaped specimens were measured using the spectrophotometer on white and black backgrounds (n = 6). The ${\Delta}Es$ and ${\Delta}TPs$ of one day, one week, and one month immersion in coffee or water were calculated. The values of each material were analyzed by two-way ANOVA and Tukey's multiple comparisons (${\alpha}=0.05$). The ${\Delta}Es$ after prophylaxis paste polishing of 1 month coffee immersion specimens, water sorption and solubility were also evaluated. Results: After one month in coffee, ${\Delta}Es$ of CAD/CAM composite resin blocks and restorative composites ranged from 1.6 to 3.7 and from 2.1 to 7.9, respectively, and ${\Delta}TPs$ decreased. The ANOVA of ${\Delta}Es$ and ${\Delta}TPs$ revealed significant differences in two main factors, immersion periods and media, and their interaction except for ${\Delta}Es$ of TEL (Telio CAD, Ivoclar Vivadent). The ${\Delta}Es$ significantly decreased after prophylaxis polishing except GRA (Gradia Block, GC). There was no significant correlation between ${\Delta}Es$ and water sorption or solubility in water. Conclusions: The ${\Delta}Es$ of CAD/CAM blocks after immersion in coffee varied among products and were comparable to those of restorative composite resins. The discoloration of CAD/CAM composite resin blocks could be effectively removed with prophylaxis paste polishing, while that of some restorative composites could not be removed.

• 천문학회보
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• 제40권1호
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• pp.89.1-89.1
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• 2015

Period changes found in the 10 years CCD BVR photometry data (2005 - 2014) of the Intermediate Polar MU Cam will be discussed. The timings of extrema of the data are determined and the new ephemeris for the spin period and orbital period have been calculated by using multi-periodic approximation as follows: BJD(orb)=2454085.46(19)+0.19664 $10(26){\cdot}E$ and BJD(spin)=2454085.50725(91)+0.013740942(13) ${\cdot}$ $E-1.51(10){\times}10^{-12}{\cdot}E^2$. The O-C diagram shows an increasing of the spin period as $P=-2.20(14){\cdot}10^{-12}s/s$. It is also found in MU Cam that the white dwarf's rotation seems to be switched from a state of spin-down to spin-up by the white dwarf's equilibrium spin period in 2005.

• 대한치과기공학회지
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• 제33권3호
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• pp.203-210
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• 2011

Purpose: The purpose of this study was to compare color correspondence of different sizes of Vita Mark II$^{(R)}$ and TriLuxe$^{(R)}$ Feldspar blocks. Methods: The three commercially available shades(1M2, 2M2, 3M2) of Mark II & TriLuxe blocks for the CEREC$^{(R)}$ CAD/CAM system were examined. For each of three colors, three different sizes were tested, 5 blocks each. The measurements were made using a spectrophotometer equipped with an integrating sphere using the CIE $L^*$, $a^*$, $b^*$ colorimetric system. Results: The $L^*$, $a^*$, $b^*$ value of Vita Mark II$^{(R)}$ ceramic block showed significantly higher than TriLuxe$^{(R)}$ ceramic block(p<0.05). In comparing the Vita Mark II$^{(R)}$ specimen of the three different shade, color differences between materials(${\Delta}E^*$) showed the lowest value of 2.09, and the highest was 2.24. ${\Delta}E^*$ values of the materials of Vita Mark II$^{(R)}$ were higher than 2. As the size of ceramic block differed, the color correspondence of Vita Mark II$^{(R)}$ showed statistically significant difference but, this result is clinically acceptable. Conclusion: All the different sizes of the different shades of Vita TriLuxe$^{(R)}$ blocks for the CEREC$^{(R)}$ system showed the high degree of color correspondence necessary in industrially prefabricated CAD/CAM blocks. The results of the present study suggested that it would be necessary to establish the reproducible and constant color specification system for an esthetic restoration.

• Journal of Veterinary Science
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• 제19권6호
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• pp.759-770
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• 2018

Fowl adenovirus (FAdV) is distributed worldwide and causes economic losses in the poultry industry. The objectives of this study were to determine the hexon and fiber gene changes in an attenuated FAdV isolate from Malaysia in specific pathogen-free chicken embryonated eggs (SPF CEE) and its infectivity in commercial broiler chickens. SPF CEE were inoculated with 0.1 mL FAdV inoculum via the chorioallantoic membrane (CAM) for 20 consecutive passages. The isolate at passage 20 (E20), with a virus titer of $10^{8.7}TCID_{50}/mL$ ($TCID_{50}$, 50% tissue culture infective dose), was inoculated (0.5 mL) into one-day-old commercial broiler chicks either via oral or intraperitoneal routes. The study demonstrated that 100% embryonic mortality was recorded from E2 to E20 with a delayed pattern at E17 onwards. The lesions were confined to the liver and CAM. Substitutions of amino acids in the L1 loop of hexon at positions 49 and 66, and in the knob of fiber at positions 318 and 322 were recorded in the E20 isolate. The isolate belongs to serotype 8b and is non-pathogenic to broiler chickens, but it is able to induce a FAdV antibody titer. It appears that molecular changes in the L1 loop of hexon and the knob of fiber are markers for FAdV infectivity.

• The Journal of Advanced Prosthodontics
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• 제3권2호
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• pp.57-62
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• 2011

MATERIALS AND METHODS. Ceramics have a long history in fixed prosthodontics for achieving optimal esthetics and various materials have been used to improve ceramic core strength. However, there is a lack of information on how color is affected by fabrication procedure. The purpose of this study was to evaluate the effects of various dentin ceramic thicknesses and repeated firings on the color of zirconium oxide all-ceramic system (LavaTM) fabricated using CAD/CAM technology. MATERIALS AND METHODS. Thirty disc-shaped cores, 12 mm in diameter with a 1 mm thickness were fabricated from zirconium oxide based all ceramic systems ($Lava^{TM}$, 3M ESPE, St Paul, MN, USA) and divided into three groups (n = 10) according to veneering with dentin ceramic thicknesses: as 0.5, 1, or 1.5 mm. Repeated firings (3, 5, 7, or 9) were performed, and the color of the specimens was compared with the color after the initial firing. Color differences among ceramic specimens were measured using a spectrophotometer (VITA Easyshade, VITA Zahnfabrik, Bad $S{\ddot{a}}ckingen$, Germany) and data were expressed in CIELAB system coordinates. A repeated measures ANOVA and Bonferroni post hoc test were used to analyze the data (n = 10, ${\alpha}=.05$). RESULTS. $L^{\ast}a^{\ast}b^{\ast}$ values of the ceramic systems were affected by the number of firings (3, 5, 7, or 9 firings) (P<.001) and ceramic thickness (0.5, 1, or 1.5 mm) (P<.001). Significant interactions were present in $L^{\ast}a^{\ast}b^{\ast}$ values between the number of firings and ceramic thickness (P<.001). An increase in number of firings resulted in significant increase in $L^{\ast}$ values for both 0.5 mm and 1.5 mm thicknesses (P<.01, P=.013); however it decreased for 1 mm thickness (P<.01). The $a^{\ast}$ values increased for 1 mm and 1.5 mm thicknesses (P<.01), while it decreased for 0.5 mm specimens. The $b^{\ast}$ values increased significantly for all thicknesses (P<.01, P=.022). As the dentin ceramic thickness increased, significant reductions in $L^{\ast}$ values (P<.01) were recorded. There were significant increases in both $a^{\ast}$ and $b^{\ast}$ values (P<.01) as the dentin ceramic thickness increased. CONCLUSION. The number of firings and dentin ceramic thickness have a definite effect on the final color of all ceramic system tested. The mean ${\Delta}E$ value increased as the dentin ceramic thicknesses increased for zirconium-oxide based all ceramic specimens tested. However, the mean ${\Delta}E$ values were less than 3.7${\Delta}E$ units which is rated as a match in the oral environment.

• Membrane and Water Treatment
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• 제10권6호
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• pp.395-404
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• 2019

The influence of chlorine on marine bacterial communities was examined in this study. A non-chlorine-adapted marine bacterial community (NCAM) and a chlorine-adapted bacterial community (CAM, bacterial community treated with $0.2mg-Cl_2/L$ chlorine) were cultivated for 1 month. A distinct difference was observed between the NCAM and CAM, which shared only eight operational taxonomic units (OTUs), corresponding to 13.1% of the total number of identified OTUs. This result suggested that chlorine was responsible for the changes in the marine bacterial communities. Kordiimonas aquimaris was found to be a chlorine-resistant marine bacterium. The effect of intermittent chlorination on the two marine biofilm communities formed on the reverse osmosis (RO) membrane surface was investigated using various chlorine concentrations (0, 0.2, 0.4, 0.6 and 0.8 mg $Cl_2/L$). Although the average number of adherent marine bacteria on the RO membrane over a period of 7 weeks decreased with increasing chlorine concentration, disinfection efficiencies showed substantial fluctuations throughout the experiment. This is due to chlorine depletion that occurs during intermittent chlorination. These results suggest that intermittent chlorination is not an effective disinfection strategy to control biofilm formation.

• 미생물학회지
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• 제23권3호
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• pp.184-189
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• 1985

L. casei Y1T 9018은 자연적으로, 또는 mutagen처리하여 plasmid DNA 7가 curing 또는 deletion되었으며, 이러한 유천적 결함이 생긴 mutants는 다음과 같은 특성을 나타냈다. 1) 탄소원으로서 lactose가 주어졌을때 mutants의 유산 생성능이 현저히 저하되었다. 2) 탄소원으로서 glucose 맺 galactose 첨가시엔 유산 생성 정도가 정상균주와 큰 차이가 없였다. 3) 5 가시 항생제에 대한 내성 맺 lactose 이외의 당에 대한 발효능 시험 갤고파 정상과 차이가 없었다.