• Elastomers and Composites
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• 제41권2호
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• pp.88-96
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• 2006

본 연구에서는 연료 누출 시 자기 밀폐성을 갖는 연료 탱크에 사용할 수 있는 고무재료의 개발을 목적으로 발포천연고무에 카본블랙과 가공유를 $10{\sim}30phr$범위에서 혼련하여 함량에 따른 발포고무의 가황 특성, 밀도, 팽윤실험 및 표면형상을 조사하였다. 미가황 고무의 가황 특성은 가공유에 의해 $ts_2$와 $Tc_{90}$이 느려졌으나 카본블랙에 의해서는 뚜렷한 경향이 나타나지 않았다. 발포에 의한 밀도의 차는 가황 전과 비교해 1/5로 밀도가 감소하였다. 발포천연고무의 팽윤실험 측정 결과, 연료 C, 이소옥탄, 톨루엔에서는 2분 이내에 모든 발포고무에서 자기밀폐작용의 90% 이상이 완료되었다. 전자주사현미경(SEM)으로 표면형상을 관찰한 결과 sodium bicarbonate에 의한 발포는 비균등한 연속 발포 셀로 나타났다.

• Restorative Dentistry and Endodontics
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• 제25권3호
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• pp.381-389
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• 2000

Lateral condensation with gutta-percha and sealer has been shown to provide an excellent apical seal; however, the lateral condensation technique has demonstrated less favorable apical leakage results in curved canals when compared with straight canals. Placement of endodontic spreaders to within 1 to 2mm of the root canal working length has been advocated for optimum gutta-percha obturation. Due to their stiffness, stainless-steel(SS) spreaders will often fail to achieve this position in curved canals. Newly marketed nickel-titanium(NT) spreaders may offer an advantage in this regard due to the increased flexibility of these instruments. The purpose of this study was to evaluate the effect of NT finger spreader on the sealing ability in lateral condensation technique, compared with conventional SS finger spreader. Twenty four standardized resin models simulating curved canals(30 degree) were randomly placed into 2 groups and instrumented to a #30 master apical file size with Ni-Ti Profile .04 taper series using step down technique. Each groups was obturated with standardized gutta-percha cone by standard lateral condensation technique using SS finger spreader, NT finger spreader. And then, each model was sectioned horizontally with microtome at 1, 2, 3, 4, 5mm levels from the apex. At each of 5 levels, ratio of the area of gutta-percha was obtained by calculating the area of gutta-percha to the total area of the canal. The data collected were then analyzed statistically using a t test for independent samples. The results as follows ; 1. The total mean ratio of area of gutta-percha was 89.20${\pm}$7.00(%) for SS spreader group. 92.20${\pm}$5.17(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). 2. At 3mm level, the mean ratio of area of gutta-percha was 88.32${\pm}$5.41(%) for SS spreader group, 95.25${\pm}$2.60(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). At 1,2,4mm levels, NT spreader group showed greater mean ratio of area of gutta-percha than SS spreader group, too. But there was no statistically significant difference. 3. At 5mm level, the mean ratio of area of gutta-percha was 91.83${\pm}$3.42(%) for SS spreader group, 87.91${\pm}$3.68(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). This study concluded that the NT spreader demonstrated somewhat favorable apical sealing effect than SS spreader in prepared curved canals. The clinical use of NT spreaders may enhance our ability to create better apical seals in curved canals, but further studies in this area will help clarify some of the remaining areas with which practitioners are concerned, such as compaction forces exerted by NT spreaders.

• 한국안전학회지
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• 제12권3호
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• pp.83-89
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• 1997

The behaviors of flame propagation and quenching ability in a pipe were investigated to make a design criteria of flame arrester. The effects of the number of wire gauzes and free area on the quenching ability were discussed. Experimental results showed that the flame velocity was important factor of the quenching ability. The flame velocity in case of closed pipe was increased about twenty times faster then that of opened. The quenching ability was increased about 10% with 3% decrease of free area and it was changed significantly by the sealing condition of the pipe end. The quenching flame velocity can be estimated by using experimental equations.

• Restorative Dentistry and Endodontics
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• 제13권1호
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• pp.113-120
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• 1988

The purpose of this study was to evaluate and compare the sealing ability of ZOE, FR and AH-26. Seventy two upper and lower anterior and premolor teeth were randomly selected and instrumented in a conventional method with K-file. After instrumentation and dry the canal, the teeth were divided into 3 groups and twenty four teeth in each group were filled with ZOE, FR, and AH-26 respectively. All the specimens were immersed into Indian Ink and decalcified in nitric acid and cleared in methyl salicylate. The apical leakage was evaluated by measuring the degree of ink penetration with caliper at the intervals of 1 day, 7 days and 14 days. The results were as follows; 1. In AH-26 and FR groups, there was increase in penetration related to increased time of immersion in the ink. 2. FR group showed the least penetration in 3 groups. 3. Statistics showed that there was no significant difference among the each sealer groups.

• Restorative Dentistry and Endodontics
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• 제12권2호
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• pp.55-63
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• 1987

The purpose of this study is to evaluate the effect of dentin bonding agents on marginal leakage. V-shaped cavities were prepared on the faciocervical area of 140 extracted human teeth. In Groups of twenty cavities, they were restored as follow: Group 1 with enamel bonding resin and Silux, Group 2 Scotchbond and Silux, Group 3 enamel bonding resin and Heliomolar, Group 4 Dentin Adhesit and Heliomolar, Group 5 enamel bonding resin and Durafill, Group 6 Dentin Adhesive and Durafill, Group 7 Chembond. All specimens were thermocycled alternatively at $4^{\circ}C$ and $60^{\circ}C$ of 2% methylene blue dye solution, and sectioned faciolingually with diamond disk under water spray. The sectioned specimens observed with stereo microscope. Following results were obtained: 1. The groups filled with Scotchbond-Silux or Dentin Adhesit-Heliomolar had appeared lesser marginal leakage compared with the groups with enamel bonding resin-Silux or enamel bonding resin-Helimolar. 2. The group filled with Dentin Adhesive-Durafill did not show the reduction of the marginal leakage compared with the group with enamel bonding resin-Durafill. 3. There was significant difference among the four dentin bonding agents. Scotchbond showed the greatest marginal sealing ability, and Dentin Adhesit was the next. The marginal sealing ability of Dentin Adhesive was the worst.

• Restorative Dentistry and Endodontics
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• 제35권5호
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• pp.335-343
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• 2010

연구목적: 본 연구의 목적은 수종의 sealer를 이용하여 각기 다른 양의 잔여수분이 존재하는 근관을 충전 시, 근관충전의 sealing ability를 glucose leakage model로 평가하는 것이다. 연구 재료 및 방법: 발치된 90개의 단근치를 치관부를 잘라내고 #45 / 0.06 taper까지 확대한 후, 12개의 실험군 (n = 7)과 2개의 대조군 (n = 3)으로 나누었다. 실험군을 3가지 습윤 상태에서 (a, DRY; b, PAPER POINT DRY; c, WET) 4종류의 sealer로 (Group 1-3: Sealapex; Group 4-6: AH plus; Group 7-9: Tubuli-seal; Group 10-12: EndoRez), warm vertical compaction method를 이용해 충전하였다. $37^{\circ}C$, 습도 100%에서 7일 동안 보관하고 glucose leakage model을 이용하여 치관부로부터 치근부 방향의 미세누출을 정량화하였다. 1, 3, 7, 14, 21, 30일 째 누출된 glucose의 농도를 spectrophotometer로 측정하였다. 결과: 관찰기간 동안 AH plus/DRY군 (Group 4)이 12개 그룹 중 가장 적은 양의 leakage를 보였다 (20.78 mmol/L). 반면에 Tubuli-seal/WET군 (Group 9)이 12개 그룹 중 가장 높은 양의 leakage를 보였다 (178.75 mmol/L). 결론: 본 연구의 결과는 충전 시 근관 내의 습윤 상태와 sealer 종류가 microleakage에 유의한 영향을 미친다는 것을 입증하였다. 그러므로 sealer 종류에 따라 각기 다른 근관 건조 방법을 사용하는 것이 근관치료에서 더 좋은 결과를 얻을 수 있는 방법일 것이다.

• Journal of Biosystems Engineering
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• 제27권5호
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• pp.399-408
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• 2002

The sweet persimmons are producted 227,394 tons per year in Korea. They are preserved at cold storage after wrapping them in packing vinyl to maintain quality. Using conventional handwork, a skillful worker could probably produce only 1,000 packings a day. Hiring many skilled-labors to wrap sweet persimmons in packing vinyl seems to be difficult because of the recent rural crisis. Therefore, it was necessary to be developed for the automated ordering and packing unit that is convenient and laborsaving. This study were summarized as follows : Success rates of 99%, 100%, and 88% were observed for ordering parts, sealing and cutting films, and sealing films in the inlet part, respectively. The time required per 1 cycle was 16 seconds and the developed unit performed 225 cycles an hour. The unit showed an ability of 1,125 pieces per hour. Therefore, the productivity was 10 times greater than that of skillful handwork.

• Asian Pacific Journal of Cancer Prevention
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• 제15권23호
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• pp.10469-10473
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• 2015

Background: Solanum nigrum L. has been used in traditional Chinese medicine because of its diuretic and antipyretic effects. The present research concerned effects of crude polysaccharides isolated from Solanum nigrum L. on erythrocyte membranes of tumor-bearing $S_{180}$ and $H_{22}$ in mice. Materials and Methods: Fluorescence-labeled red blood cell membranes were used with DPH fluorescence spectrophotometry to examine erythrocyte membrane fluidity, and colorimetry to determine degree of erythrocyte surface membrane blocking. Extent of reaction by tumor-bearing mice with the enzyme erythrocyte membrane bubble shadow detection of red cell membrane variation in the degree of closure before and after administration. Results: Solanum nigrum polysaccharide could significantly improve the $S_{180}$ and $H_{22}$ tumor-bearing mice erythrocyte membrane fluidity, compared with the control group, the difference was significant (p<0.01), SNL can significantly improve the red blood cell membrane and then $S_{180}$ tumor-bearing mice sealing ability, compared with the negative control group, the difference was significant(p<0.05, p<0.01). $H_{22}$ tumor-bearing mice can increase red cell membrane and then sealing ability, the difference was significant (p<0.05). Solanum nigrum polysaccharide degree of fluidity and blocking two transplanted tumors in mice restored the ability to raise the red cell membrane has a significant effect. Conclusions: Solanum nigrum L.-type mice transplanted tumor can affect the red blood cell membrane fluidity and re-closed, through the red cell membrane of red blood cells to enhance the immune function of the possibility of erythrocyte immunity against tumor formation garland provide experimental basis.

• Restorative Dentistry and Endodontics
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• 제24권1호
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• pp.222-232
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• 1999

The purpose of this study was to evaluate the effect of heated spreader on the sealing ability of lateral condensation, compared with regular cold spreader. Forty two extracted human teeth with single canal were randomly placed into 3 experimental groups, and four additional teeth were used as positive and negative controls. Each group was prepared with Ni-Ti Profile #40 using step-down technique and obturated with standardized colored gutta-percha cone by standard(cold) lateral condensation technique, warm lateral condensation technique with Endotec and hot spreader soaked in glass bead sterilizer, each with Sealapex sealer. Control groups were not obturated, but prepared. After 2 days in 2% methylene blue, the teeth were invested and made into transparent resin blocks. And then, each block was sectioned horizontally with microtome at 1, 2, 3, 4, 5 mm levels from the apex. The linear extent of dye penetration was examined with stereomicroscope at ${\times}$20 magnification. At each of 5 levels, ratio of the area of gutta-percha was obtained by calculating the area of gutta-percha to the total area of the canal. The data collected were then analyzed statistically using an analysis of variance(ANOVA) and Scheffe test. The results were as follows ; 1. All experimental groups produced the apical microleakage. 2. The mean leakage was 1.57${\pm}$0.76mm for cold spreader group, 0.86${\pm}$0.95mm for Endotec spreader group, and 0.64${\pm}$0.93mm for hot spreader group. The difference between hot spreader group and cold spreader group was statistically significant(p<0.05). 1. At the 1 mm level, the mean ratio of area of gutta-percha was 74.58${\pm}$13.15(%) for cold spreader group, 65.42${\pm}$14.62(%) for Endotec spreader group, and 80.72${\pm}$14.63(%) for hot spreader group. There was statistically significant difference between hot spreader group and Endotec spreader group(p<0.05). 2. At the 2mm level, the mean ratio of area of gutta-percha was 87.86${\pm}$11.22(%) for cold spreader group, 66.55${\pm}$14.02(%) for Endotec spreader group, and 92.93${\pm}$7.24(%) for hot spreader group. There was statistically significant difference between Endotec spreader group and other two spreader groups(p<0.05). 3. At the level 3, 4, 5 mm, there was no statistically significant difference between each group. Within the limits of the results of this experiment, warm lateral condensation technique with hot spreader soaked in a glass bead sterilizer demonstrated favorable apical sealing effect and improved density of gutta-percha mass. Thus, it is thought that this obturation technique is effective for clinical use and beneficial to reduce condensation forces, also economical and easy. Lateral condensation, Heated spreader, canal sealing, Microleakage.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2002년도 추계학술대회
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• pp.685-685
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• 2002

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