• 대한치과의사협회지
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• 제58권11호
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• pp.683-689
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• 2020

Dentin surface of non-carious lesion is usually attached with oral biofilm. The biofilm should be removed before application of restorative material, because it may reduce the bond strength of adhesive system. The aim of this study was to evaluate the microtensile bond strength, when the biofilm was removed with brush or bur. Twenty extracted human third molars were sectioned horizontally to obtain dentin surface. Specimen were divided randomly into four group. Biofilm formation was performed in three group, except for Group 1 (negative control). Biofilm was removed as follows: Group 3, using ICB brush; Group 4, using lowspeed round bur #2. Group 2 (positive control) was not removed Biofilm. And in all four groups, the adhesive system (Optibond FL, Kerr) was applied to etched dentin surface, and resin composite was built up in three 1mm increments. After 24 hour storage in distilled water, the teeth were perpendicularly sectioned to obtain beams (1 × 1 mm2). Microtensile bond strength was measured and the data were statistically analyzed using one-way ANOVA and Tukey's post hoc test (p<0.05). Group 4 showed the highest microtensile bond strength (p<0.05), Group 3 showed no significant improvements when compared to Group 1. Group 2 showed lowest microtensile bond strength (p<0.05). When restoring a non-carious cervical lesion, it is essential to remove the biofilm present on the dentin surface. In addition, in the method of removing the biofilm, both the brush removal method and the bur removal method were effective.

• 한국식품조리과학회지
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• 제19권4호
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• pp.511-520
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• 2003

This study was carried out to determine the effects of various contents of kiwifruit contents on the quality characteristics of mixed polysaccharide gels made from $\kappa$-carrageenan and locust bean gum. The color value, gelling temperature, melting temperature, break down rate, syneresis, rupture properties, TPA properties and sensory properties of mixed polysaccharide gels with various contents of kiwifruit contents were measured. As the kiwifruit contents was increased, the lightness (L), yellowness (b) and greenness (-a) of the mixed polysaccharide gels increased. There were no differences in the color values of gels during storage. As the kiwifruit content was increased, the gelling and melting temperatures of the mixed polysaccharide gels also increased. The mixed polysaccharide gels with high kiwifruit contents were difficult to melt, and it seemed that the addition of kiwifruit to the mixed polysaccharide gels could improve the thennal stability of the gels. The syneresis of the gel increased with increasing storage time, whereas the addition of kiwifruit to the gel resulted in suppression of syneresis. With regard to the rupture properties, stress, energy and strain, they were all decreased with increasing kiwifruit contents. The TPA properties, adhesiveness, hardness and chewiness increased and cohesiveness decreased with increasing kiwifruit contents. The results showed that the gel became tough and adhesive, and could be easily broken under small deformation, with increasing kiwifruit contents. The sensory evaluation showed that the green color, aroma, sweetness and sourness increased with increasing kiwifruit contents. The texture, adhesiveness, springiness and cohesiveness decreased, and brittleness and hardness increased, with increasing kiwifruit contents. The overall acceptability of the gel with 30% kiwifruit content was the highest. Thus, mixed polysaccharide gels made from kiwifruits could be useful, as the addition of kiwifruit to a mixed polysaccharide gel results in a good aroma, taste and stability, despite a lowering of the textural properties.

• 대한치과교정학회지
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• 제46권6호
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• pp.364-371
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• 2016

Objective: With the introduction of third-generation light-emitting diodes (LEDs) in dental practice, it is necessary to compare their bracket-bonding effects, safety, and efficacy with those of the second-generation units. Methods: In this study, 80 extracted human premolars were randomly divided into eight groups of 10 samples each. Metal or polycrystalline ceramic brackets were bonded on the teeth using second- or third-generation LED light-curing units (LCUs), according to the manufacturers' instructions. The shear bond strengths were measured using the universal testing machine, and the adhesive remnant index (ARI) was scored by assessing the residual resin on the surfaces of debonded teeth using a scanning electron microscope. In addition, curing times were also measured. Results: The shear bond strengths in all experimental groups were higher than the acceptable clinical shear bond strengths, regardless of the curing unit used. In both LED LCU groups, all ceramic bracket groups showed significantly higher shear bond strengths than did the metal bracket groups except the plasma emulation group which showed no significant difference. When comparing units within the same bracket type, no differences in shear bond strength were observed between the second- and third-generation unit groups. Additionally, no significant differences were observed among the groups for the ARI. Conclusions: The bracket-bonding effects and ARIs of second- and third-generation LED LCUs showed few differences, and most were without statistical significance; however, the curing time was shorter for the second-generation unit.

• 한국의류학회지
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• 제34권1호
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• pp.167-174
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• 2010

This paper aims to examine the status of sizing specifications for disposable sanitary pads on the market and to offer information on product design that reflect the requests of consumer by gathering opinion through the practical experience of consumers. Seventy-six varieties of sanitary pads on market are measured and the evaluations of wearing comfort were investigated by the questionnaire and interview for sixty three varieties of sanitary pads. As a result, they were classified into five sizes related with length but vaguely related with thickness and width. Thickness is distinguished by the compressibility that is marked as slim or ultra slim by the same brand. However, there is no sizing consistency for all products. The result shows that there is some confusion for consumers to choose desired sizes, In addition, the perception of wearing is categorized into four factors that are product performance, size and fit, wearing feeling and margin of action, and adhesive property and wrapping. The manufacturing specifications for the sanitary pads on domestic market, the requests of consumers for sanitary pad design modifications, and proposals for follow-up studies were figured out through this research.

• 한국산학기술학회논문지
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• 제11권5호
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• pp.1741-1746
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• 2010

본 연구는 건축자재로 널리 사용되는 PVC 바닥상재 표면을 오염성 및 정전기로부터 보호하기 위하여 기존에 사용하는 광경화형 우레탄-아크릴 수지에 내오염/대전성을 향상시킨 광경화형 내오염 코팅액 개발에 관한 것이다. PVC 바닥상재용으로 사용되는 내오염성이 없는 우레탄-아크릴 수지에 4가 암모늄을 사용한 수용성 대전방지제와 아크릴용 대전방지제, 폴리우리탄용 대전방지제를 수지의 양 대비 함량(wt%) 5~20%로 변화하여 첨가한 후 배합하여 수지의 내오염/대전성을 향상시킨 내오염 코팅액을 제조하였다. 제조한 내오염 코팅액은 코팅 층의 두께조절이 가능한 코팅(Bar-coating)을 사용하여 PVC 바닥상재에 코팅 한 후 내오염성, 대전성, 부착력, 코팅두께 등의 코팅 층 표면물성을 평가하였다. 연구결과, 수지에 수용성대전방지제 15%를 혼합하여 제조한 코팅액을 Bar-coater No.12로 코팅한 코팅표면이 전기저항($3.24{\times}10^9{\Omega}/cm^2$), 내오염도(매직 Test, 먼지부착 Test) 및 부착력(100%) 모두 가장 좋은 물성을 보였다. 전반적으로 함량이 많을수록 전기저항과 오염도에서 우수한 것으로 나타났다. 그러나 대전방지제가 과량으로 들어간 경우 migration 현상이 보이는 것을 알 수 있었다.

• 대한관절경학회지
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• 제11권1호
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• pp.24-31
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• 2007

목적: 견관절 유착성 관절 낭염으로 진단된 환자들에서 회전근 개 병변의 동반 정도를 자기 공명 관절 조영술(magnetic resonance arthrography, MRA) 및 초음파 (ultrasonography, USG)를 이용해 평가해 보았으며, 검사 소견에 있어서 MRA 및 USG의 차이점을 알아보았다. 대상 및 방법: 2005년 6월부터 12월까지 견관절 유착성 관절 낭염으로 진단한 연속된 80명의 환자를 대상으로 전향적 연구를 시행하였다. 무작위로 나누어 MRA 혹은 USG를 시행하였으며, 견관절 유착성 관절 낭염 환자에서 극상근을 중심으로 한 회전근 개 병변의 동반 정도를 조사하였다. 결과: 여섯 예(MRA 4, USG 2, 8%)에서 극상근에 소규모(1cm 이하)의 전층 파열을 보였으며 극상근의 부분 파열은 21예(MRA 12, USG 9, 26%)에서 관찰되었다. 뿐만 아니라 극상근의 건 병증(tendinopathy)이 15예(MRA 7, USG 8, 19%)에서 관찰되어, 총 42예(53%)에서 극상근 병변을 동반하고 있었다(MRA 23, 68% USG 19, 41%). 견갑하근의 부분 파열을 동반한 경우는 9예(MRA 6, USG 3, 11%)로 관찰되었다. 두 군간 극상근 병변의 동반 정도에 유의한 차이는 없었다(p>0.5). 결론: 견관절 유착성 관절 낭염 환자들을 대상으로 하여 시행한 MRA 또는 USG검사 상, 약 반 수(53%)의 환자들에서 극상근의 병변이 동반된 소견을 보였다. 유의한 차이는 없었으나, USG군 보다 MRA군에서 다소 높은 회전근 개 병변의 동반소견을 보였으며 이는 MRA가 USG보다 해상도가 더 뛰어 난 데서 기인한 것으로 생각된다.

• 한국해양공학회지
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• 제25권6호
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• pp.56-59
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• 2011

The demand for cold rolled steel (CR) for structural members is gradually increasing. If no surface treatment (coating for corrosion resistance) for CR is conducted, its use is very limited because CR is vulnerable to corrosion. Therefore, we need to develop a coating solution to provide high corrosion resistance for CR. In this study, an organic/inorganic coating solution with Si and Ti (Si polysilicate 7 wt.% + Urethane 13 wt.% + Ti amorphous 0.5 wt.%; LR-0727(1)) was used to evaluate the corrosion resistance of CR under a salt spray test. The specimens with the LR-0727(1) coating were heat treated in a drying oven at $120{\sim}210^{\circ}C$for 5 min. The corrosion resistance was investigated using a salt spray test of 7 h. In addition, an adhesive test was conducted. Rust showed under a heat treatment of $150^{\circ}C$, but no vestiges were found over $160^{\circ}C$. The specimens with heat treatment at $160^{\circ}C$ or more did not experience delamination. From these results, it is considered that the temperature limit for optimum heat treatment is $160^{\circ}C$ considering energy efficiency.

• Journal of Welding and Joining
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• 제14권4호
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• pp.99-108
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• 1996

The microstructure and bond strength are examined on the SiC/SiC and SiC/mild steel joints brazed by the Ag-Ti based alloys with different Ti contents. In the SiC/SiC brazed joints, the thickness of the reaction layers at the bond interface and the Ti particles in the brazing alloy matrices increase with Ti contents. When Ti is added up to 9 at% in the brazing alloy. $Ti_3SiC_2$ phase in addition to TiC and $Ti_5Si_3$ phase is newly created at the bond interface and TiAg phase is produced from peritectic reaction in the brazing alloy matrix. In the SiC/mild steel joints brazed with different Ti contents, the microstructure at the bond interface and in the brazing alloy matrix near SiC varies similarly to the case of SiC/SiC brazed joints. But, in the brazing alloy matrix near the mild steel, Fe-Ti intermetallic compounds are produced and increased with Ti contents. The bond strengths of the SiC/SiC and SiC/mild steel brazed joints are independent on Ti contents in the brazing alloy. There are no large differences of the bond strength between SiC/SiC and SiC/mild steel brazed joints. In the SiC/mild steel brazed joints, Fe dissolved from the mild steel does not affect on the bond strength of the joints. Thermal contraction of the mild steel has nearly no effects on the bond strength due to the wide brazing gap of specimens used in the four-point bend test. The brazed joints has the average bond strength of about 200 MPa independently on Ti contents, Fe dissolution and joint type. Fracture in four-point bend test initiates at the interface between SiC and TiC reaction layer and propagates through SiC bulk. The adhesive strength between SiC and TiC reaction layer seems to mainly control the bond strength of the brazed joints.

• 유기물자원화
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• 제7권1호
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• pp.1-12
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• 1999

인공 배양토의 기능을 향상시키기 위해서 정수장 슬러지를 주원료로한 인공 배양토 개발에 관한 연구를 수행하였다. 기존에 시판되고 있는 인공 배양토보다 제지 슬러지, 하수 슬러지, 완숙 퇴비, 정수장 슬러지를 각각 40, 20, 10, 30% 혼합하여 제조한 인공 배양토가 perennial ryegrass, 싸리나무에 대한 식물생육에 효과적이었다. 식물독성실험에서도 정수장 슬러지를 혼합한 시료에서는 식물독성이 나타나지 않았다. 또한 정수장 슬러지는 인공 배양토의 보수력 및 접착력 증가에 긍정적인 영향이 있었다. 정수장 슬러지는 알루미늄을 다량 함유하고 있으나, 퇴비와 혼합하였을 경우 pH 2의 낮은 pH에서 Al의 용출이 거의 없었다.

• Journal of the Korean Wood Science and Technology
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• 제48권6호
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• pp.791-806
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• 2020

본 연구에서는 공학목재로 목구조건축에 주로 사용되는 집성재 및 CLT 그리고 Ply-lam CLT의 블록전단시험을 실시하여 강도 및 파괴 유형을 비교 분석하였다. 이를 통해 Ply-lam CLT의 라미나 및 합판의 수종, 접착제의 종류 및 Layer구성 등 최적생산을 위한 제조조건을 구명하고자 하였으며 그 결과는 다음과 같다. 블록전단시험을 통해 집성재, Ply-lam CLT, CLT 순으로 높은 강도를 나타냈다. 특히, 낙엽송 합판과 낙엽송 라미나의 복합구조로 제조되는 Ply-lam CLT의 전단강도는 집성재 전단강도 기준인 7.1 N/㎟을 통과하였다. 아울러 본 연구에서는 집성재, CLT, Ply-lam 접착에 사용된 접착제 종류에 따른 전단강도의 차이는 나타나지 않았다. 그러나 Ply-lam CLT의 경우에는 라미나와 합판의 수종에 따라 Ply-lam CLT의 전단강도의 차이를 나타냈다. 그 결과는 낙엽송 > 남양재 ≒ 육송 합판 순으로 높은 강도를 나타났다. Ply-lam CLT의 최적 구성은 낙엽송 합판과 낙엽송 라미나를 사용하는 경우이며 접착제는 용도에 따라 PRF, PUR을 선정하여 사용하면 될 것으로 판단된다. 목질재료 유형에 따른 전단강도 파괴 양상 결과 분석을 통하여 집성재는 shear parallel-to-grain, CLT는 rolling shear, Ply-lam CLT는 shear parallel-to-grain과 rolling shear가 복합적으로 나타났다. 이는 전단강도 결과와 밀접한 관련이 있으며 rolling shear로 인하여 CLT보다 Ply-lam CLT에서 더 높은 전단 강도를 나타내는 것으로 판단된다.