• 한국환경복원기술학회지
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• 제25권1호
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• pp.1-10
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• 2022

This study was conducted to investigate the germination characteristics through the temperature change treatment compared to the general room temperature immersion treatment of the native species, the Larix kaempferi, and the Berula platyphyllavar. japonica seeds, and to obtain basic data for the production of healthy seedlings with high productivity and efficiency. As a result, the germination rate of the larch seeds showed a significant difference according to room temperature and temperature immersion treatment, and the average germination days of the birch seeds showed a significant difference according to room temperature immersion and temperature immersion treatment. On the other hand, there was no significant difference in germinal uniformity. The results of the study are as follows. First, the results of the analysis of the fallen leaves were the highest germination rate in the treatment of 1.5 days of hot water and 1.5 days of cold water, the fastest germination rate, the lowest average germination day, and the highest germination uniformity. This is the best result in most items, and the change temperature immersion treatment of hot and cold baths was superior to the conventional room temperature immersion treatment. Second, the results of birch tree showed that the germination rate was the highest in 1.5 days of hot water and 1.5 days of cold water. The average germination day is 1.5 days of cold water 1.5 days of hot water 1.5 days, but the difference between 1.5 days of hot water and 1.5 days of cold water is 0.01 days. The highest germinated uniformity was found in 1.5 days of cold water and 1.5 days of hot water. As a result, in the case of larch and birch, the seed temperature immersion (1.5 days of hot water, 1.5 days of cold water) treatment is superior to the existing three-day immersion treatment in various analysis methods, and it is expected that productivity and efficiency can be improved at a low cost in a short period of time at the seedling production site through seeds.

• 펄프종이기술
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• 제41권3호
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• pp.60-64
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• 2009

Paper is easily damaged by physical and chemical deterioration under several factors. Damaged paper cultural heritage is usually restored by Lining. A traditional method of Lining is attaching the lining paper behind the original paper cultural heritage using starch and water. It supports the weakened quality of paper. In Japan, paper cultural heritage is restored with "Washi" which is made from mixture of Paper mulberry and Japanese cedar. In the west, the lining paper made from Paper mulberry, which has extraordinary excellent conservativeness, is usually used as a restoration material for paper. But Japanese Washi has dominated the demand for restoration materials as the most preferred restoration paper, and most kinds of paper made from Paper mullbery have been called as 'Japanese paper'. Result showed that the strength of the Korean lining papers was generally higher than that of the Japanese ones. As a result from measuring the rate of dimensional change after water-immersion and drying, sample B of the Korean lining papers and sample E of the Japanese lining papers showed the highest stability.

• 대한치과보철학회지
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• 제41권5호
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• pp.656-673
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• 2003

Statement of problem : Long-term exposure of dental porcelain to saliva during temporary cementation of a porcelain-fused to metal (PFM) restoration could affect mechanical strength of dental porcelain if the restoration is refired. Purpose : This work was performed to verify the effect of water on the mechanical strength in aged dental porcelain. Material and method : 63 specimens(Vintage Metalbond opaque and opal powder) were distributed to three experimental groups ; non-water immersed control, immersed and pedried, and immersed and non-predired groups. The changes in flexural strength and fracture toughness after specimen refiring related to Fourier Transform Infrared (FT-IR) spectroscopy. Results : 1. The FT-IR reflectances assigned to molecular bonds of $H_2O$ were noted as significantly different between the first-fired group and three refired groups and between two water-immersed groups and control group after refiring(p<0.05). They were also significantly different between predried group and non-predried group after refiring(p<0.05) 2. For opal specimens, FT-IR absorbances for hydrogen bond of $H_2O$ and silanols were significantly higher in non-predried group than in predreid group(p<0.05). 3 Predried opal group showed the highest mean flexural strength(p<0.05). Non-predried group indicated higher mean flexural strength than control group(p<0.05). 4. The mean fracture toughness for predired group was higher than non-predried group(p<0.05). 5. The difference of leucite crystal size is noted between control group and water-immersed, predried group in scanning electron microscopic study(${\times}10000$).

• 한국CDE학회논문집
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• 제21권1호
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• pp.90-98
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• 2016

When ships and offshore plants are flooded or the floating crane is equipped with a heavy object, these floating structures are excessively inclined. In this case, immersion, heel, and trim affecting the hydrostatic restoration performance are very large and are coupled each other. In this paper, in order to calculate a static equilibrium position of floating structures with excessive inclination, the nonlinear governing equations were constructed by sequential linearization. In the governing equation, the immersion, heel, and trim are fully coupled, and the equations are represented using a plane area, a primary moment, and a moment of inertia of the water plane area. Therefore, it is possible to calculate the additional factor related the water plane area for estimating stability. Position and orientation of the floating structure are obtained by iterative calculation. The calculated results are compared with the previous studies in the aspect to the performance and the accuracy.

• 대한치과보철학회지
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• 제29권1호
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• pp.13-22
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• 1991

This study investigated the effects of surface treatment on the tensile bond strength of resinbonded prosthesis. The Rexillium III specimens were treated with $50{\mu}m\;Al_2O_3$ blasting. Type IV gold alloy specimens were treated with $400^{\circ}C$ heating and tin plating method. All specimens were bonded with MBAS composite resin cement and followed by immersion test into the $37^{\circ}C$ water bath for 7 days. The specimens were debonded in tension with an Instron machine and observed with SEM. The modes of failure were recorded also. The following conclusions were obtained : 1. The tensile bond strength decreased in following order. $50{\mu}m\;Al_2O_3$ basted Resillium III group, Type IV gold alloy group treated with $400^{\circ}C$ heat and tin plating type IV gold alloy group, and statistical significant differences were observed(p<0.05). 2. The tensile bond strength decreased in all groups after 7 days immersion test, but statistical significant differences were observed in Rexillium III specimens only. 3. The sharp and irregular surface were observed in Rexillium III, but $400^{\circ}C$ heat treated and tin plated groups had round and broad surface in SEM. 4. The models of bond failure were cohesive-adhesive failure mainly.

• Restorative Dentistry and Endodontics
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• 제18권1호
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• pp.215-226
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• 1993

Color stability of tooth colored restorative resins is an important factor, particularly in anterior teeth restoration. The purpose of this study was to evaluate the color stability and opacity change of several light curing composite resins. Specimens of eight composite resins(Prisma AP. H., Brilliant Enamel, Charisma, Durafil, Helio Progress, Herculite XR, P-50 and Silux Plus) were divided into two groups : In Group 1, the specimens were polymerized by visible light curing unit for 60 seconds on both sides and in Group 2, the post-cured specimens were heat tempered by light/heat curing unit for 45 units(about 18 min.). All specimens were stored in distilled water at $60^{\circ}C$ for 30 days. The color characteristics($L^*,a^*,b^*$) and opacity of the specimens before and after immersion were measured by spectrocolorimetry and the total color difference(${\Delta}E^*$) and opacity change (${\Delta}Y%$) were computed. The results obtained were as follows : 1. SP and APH in both groups, DF, HP and HXR in Group 1 showed ${\Delta}E^*$-value above 2.0. 2. DF, HP, SP and HXR in Group 1 showed higher ${\Delta}E^*$-value than in Group 2, but the others had no significant difference. 3. The opacity of CH and HXR in Group 1, and of CH and BE in Group 2 decreased after immersion, while that of the others increased. 4. Opacity change of BE, P50 and HXR was significantly different between Group 1 and 2. These results suggest that color change in the post-cure heat tempered specimens by light/heat curing unit was smaller than that of the specimens polymerized by visible light curing unit. No clinically detectable opacity changes were noted for any materials in either goup.

• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.124-134
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• 1994

The shade of restorative materials is very important for successful restoration esthetically harmonized with the natural tooth. The purpose of this study was to evaluate the color stability and the opacity change of conventional chemical setting and visible light curing glass-ionomer cements for restorative esthetic filling. Specimens of each brand (GC Fuji II and Fuji II LC) were uniformly prepared and divided into three groups: In group l(control group), the specimens received no surface treatment; in group 2, the specimens were coated with varnish and the excess gently blown off; and in group 3. the specimens were coated with light-cured bonding resin and irradiated by a visible light curing unit for 20 seconds on both sides. All specimens were stored in distilled water at $37^{\circ}C$ and checked after for 24 hours. 2 months. 4 months, 6 months. and 8 months. The color characteristics($L^*,\;a^*,\;b^*$) and the opacity(Y%) of all the samples were measured by a spectrocolorimeter and the total color differences(${\Delta}E^*$) and opacity changes(${\Delta}Y%$) were computed. The following results were obtained : 1. The total tolor differences in all groups increased with time. 2. The total color differences of the LC groups after immersion for 8 months in distilled water at $37^{\circ}C$ were lower than those of GC groups(p<0.01), and the total color differences of the varnish or the light-cured bonding resin coated groups were lower than those of the control group with glass-ionomer cements which had no surface treatment(p<0.01). 3. In all groups the translucency decreased with time. 4. In the control group and the varnish coating group. the opacity changes of the GC groups were lower than those of the LC groups(p<0.01) and in the light-cured bonding resin coated group, there was no significant difference between the GC group and the LC group. 5. The opacity changes of the varnish or the light-cured bonding resin coated groups were lower than those of the control group(p<0.01). These results suggest that color change and opacity of conventional chemical setting and light cured glass-ionomer cement were increased with time, and the color changes and the opacity changes of a control group after immersion for 8 months in distilled water at $37^{\circ}C$ were greater than those of the varnish or the light-cured bonding resin coated groups.

• 대한치과보철학회지
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• 제52권4호
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• pp.312-316
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• 2014

목적: 본 연구에서는 지르코니아 수복물의 접착에 사용되는 레진 시멘트의 파괴인성을 측정하고 각 레진 시멘트의 다양한 수중 보관 기간이 파괴 인성에 미치는 영향에 관하여 알아보고자 하였다. 재료 및 방법: 세가지 종류의 레진 시멘트(Panavia F2.0, Clearfil SA luting, Zirconite)를 사용하여 single edge notched 형태의 시편($3mm{\times}6mm{\times}25mm$)을 제작하였다. 각 시편은 $37^{\circ}C$ 증류수에서 1일 (대조군), 30일, 90일, 180일 동안 보관하였다 (n=5). 만능시험기를 이용하여 0.1 mm/s 속도로 삼점굽힘 시험을 시행하고, 파절 시의 최대하중으로 파괴인성($K_{IC}$)을 계산하였다. 측정값은 일원분산분석과 다중분석을 위한 $Scheff{\acute{e}}$ test를 사용하였고, 유의수준은 0.05로 하였다. 결과: 대조군에서 Panavia F2.0가 $3.41{\pm}0.64MN{\cdot}m^{-1.5}$로 가장 높은 $K_{IC}$를 보였으며 Zirconite가 $3.07{\pm}0.41MN{\cdot}m^{-1.5}$, Clearfil SA luting이 $2.58{\pm}0.30MN{\cdot}m^{-1.5}$으로 가장 낮은 $K_{IC}$를 보였으나, 재료간에 유의성 있는 차이는 없었다. 수중보관 기간이 증가함에 따라 Panavia F2.0의 값은 감소였고, Clearfil SA luting과 Zirconite는 증가하였으나, 통계적으로 유의한 차이를 보이지 않았다. 결론: 지르코니아 수복물 전용 레진 시멘트의 파괴인성은 다른 일반 시멘트에 비해 대체로 높으며, 이러한 파괴인성은 수중 보관에 영향을 받지 않는다.

• 한국식품저장유통학회지
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• 제24권5호
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• pp.600-607
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• 2017

본 연구는 과열증기(superheated steam, SHS) 기술을 이용하여 높은 품질의 편의식 식자재로서의 무를 제조하고, 제조한 무의 저장 중 품질변화를 알아보기 위해 수행하였다. 적당히 자른 무를 1차 과열증기(오븐온도 $250^{\circ}C$, 증기온도 $370^{\circ}C$)에서 각각 0, 3, 5 및 7 분간 처리한 후, $80^{\circ}C$에서 6 시간동안 완전히 건조 하였다. 본 연구 결과, 혼합용액(음용수:설탕:식초:소금=2:1:0.8:0.1)에서 복원한 무가 음용수만으로 복원한 무에 비해 좀 더 단단하였다. 5, 10 및 $15^{\circ}C$에서 56일간 저장한 모든 무를 품질변화를 측정하였다. 물로 복원하고 $15^{\circ}C$에 저장한 대조구 무는 저장 7일만에 부패하였다. 실험구 무는 저장 1일을 제외하고, 수분 함량에 변화가 없었다. 저장기간이 증가함에 따라 무의 단단한 조직감이 감소하였다. 혼합용액으로 복원한 무는 낮은 pH로 인해 미생물 성장이 억제되었다. 따라서 SHS의 사용과 혼합용액을 이용한 복원은 손쉽게 무 제품을 개발할 수 있었다.

• The Journal of Advanced Prosthodontics
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• 제9권5호
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• pp.387-393
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• 2017

PURPOSE. Beverages may affect the translucency of esthetic dental restorative materials.The aim of the present study was to investigate the effects of coffee and red wine on the translucency of a PICN material with two translucency levels, and finished with different methods. MATERIALS AND METHODS. 2M2 high translucent and translucent VITA Enamic hybrid ceramic blocks were investigated. Rectangular specimens with the dimensions of $12mm{\times}14mm{\times}2mm$ were prepared. The specimens were finished and polished with different methods as suggested by the manufacturer. The translucency parameters of the specimens were evaluated before and after 24 hours, 7 days, and 28 days immersion in distilled water, coffee and red wine. Translucency parameters were measured using a portable spectrophotometer. RESULTS. At the end of 28 days, there was no statistically significant difference between the groups of specimens kept in coffee (P>.05). In the red wine groups, there was a statistically significant difference between the control group and all other groups (P<.05) at the end of 28 days. CONCLUSION. The translucency of hybrid ceramic for a restoration may not be important regarding the effects of coffee on translucency change because the specimens with different translucencies and finishing methods that were immersed to coffee had similar translucency parameters at the end of 28 days. The translucency of hybrid ceramic may be important in the case of red wine, however, since the results showed that highly translucent specimens exposed to red wine demonstrated better translucency parameters than specimens made from translucent blocks at the end of 28 days.