• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.389-390
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• 2010

this study is preliminary experimental research for develop methods to utilize the natural Hwangtoh as replacement materials for the cement in concrete, via alkali activation at $60^{\circ}C$ using NaOH solution and liquefied $Na_2SiO_3$ in a manufacture process of Hwangtoh concrete binder.

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.689-698
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• 1998

The purpose of this study was to evaluate the shear bond strength of light cured glass ionomer cement to enamel surface which treated with $37\%$ phosphoric acid, $10\%$ polyacrylic acid, $1.23\%$ acidulated phosphate fluoride gel and no etching agent. To compare the shear bond strength of glass ionomer cement, light-cured composite resin and chemically-cured composite resin were empoloyed as controls. Eight experiments groups were composed. 10 specimens of each group were bonded by metal bracket by tested in universal testing machine for shear bond strength, in stereoscope for adhesive remnants index. The data were evaluated statistically by SPSS/PC+. The results were as follows. 1. Among the groups of $37\%$ phosphoric acid treated and dry and bonded with light cured glass ionomer, light cured composite resin, and chemically cured composite resin, the shear bond strength of glass ionomer group showed no significant difference to the others, but the shear bond strength of chemically cured resin showed statistically lower than that of light cured resin (p<0.05). 2. The shear bond strengths of glass ionomer cement to enamel treated group with $1.23\%$ acidulated phosphate fluoride gel and $10\%$ polyacrylic acid and $37\%$ phosphoric acid showed statistically higher than that of no etched enamel group(p<0.U). 3. In the groups of glass ionomer cement, the presence of moisture was not significantly effect to the shear bond strength (p<0.05). 4. After debonding, no etched enamel group showed less residual materials on the enamel surface than the group of enamel etched with $37\%$ Phosphoric acid.

• The korean journal of orthodontics
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• v.41 no.1
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• pp.16-24
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• 2011

Objective: The purpose of this study was to determine (1) the shear bond strength (SBS) of an antimicrobial monomer-containing self-etching primer according to ceramic bracket types and (2) the bracket-adhesive failure mode using an adhesive remnant index (ARI). Methods: A total of 90 extracted human teeth were randomly divided into 6 groups. Each group consisted of one of two ceramic brackets (monocrystalline, polycrystalline) and one of three primers (Transbond XT primer, Transbond Plus SEP, Clearfil Protect Bond) with each group containing 15 specimens. The SBS was measured, and adhesive residues left on the tooth surface were assessed. Results: The SBS of polycrystalline ceramic bracket groups was Significantly higher than that of the monocrystalline ceramic bracket groups (p < 0.001). The SBS of Transbond XT primer groups was significantly higher than those of Transbond Plus SEP groups and Clearfil Protect Bond groups (p < 0.001). All the groups showed bonding failures between the bracket base and adhesive. Conclusions: The combination of a self-etching primer with a monocrystalline bracket is recommended for clinical use, considering its acceptable SBS and mode of failure.

• Journal of dental hygiene science
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• v.14 no.1
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• pp.29-34
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• 2014

The purpose of this study was to evaluate the influence of low temperature degradation (LTD) on the bonding strength of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP). The push-shear bond test method was used to investigate the core-veneer bonding strength of industrially manufactured Y-TZP core ceramic and manufacturer recommended veneering ceramic. Four groups from ceramic-zirconia specimens (n=28; n=7 per group) were assigned into four experimental aging conditions, namely storage in an autoclave at $134^{\circ}C$ for 0, 3, 5, 10 hours. Bonding strength was obtained using a universal testing machine with crosshead speed 0.5 mm/min. Data were statistically analyzed using one-way ANOVA and Tukey's test (${\alpha}=0.05$). In bonding strength test, the group which was treated with LTD showed lower bonding strength than no treated group. The ceramic-zirconia bonding strength was affected by LTD (p<0.05). Digital microscope examination of the fracture surface showed mixed failures with adhesive and cohesive types in LTD with treated Y-TZP groups.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.3
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• pp.444-456
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• 2000

To test the shear bond strength of a new "one-bottle adhesive" system to primary dentin two commercially available one-bottle adhesives (Prime & Bond NT, Single bond) and conventional three step system(Scotchbond Multi-Purpose Plus) were included for comparison. And We observe the interfacial morphology by scanning electron microscope. 90 primary molar teeth were embedded in acrylic and buccal and lingual surface were polished to 320 grit to create standardized dentin surface for testing. After bonding of composite resin to sample surfaces according to the manufacturer s direction and 1000 times thermocycling in dwell time 30 second, Shear bond strengths of adhesives to dentin were determined using universal testing machine and analyzed by ANOVA test. Another groups of specimens were treated by hydrochloric acid to secure the resin only and those tags were evaluated under SEM for their length and forms and the morphology of the bonding sites were also observed. The result are as follows. 1. Group I(Prime & Bond NT) showed higher shear bond strength than group iI(Single Bond) and III(Scotchbond Multi Purpose Plus) but no statistically significant difference was founded between groups(p>.05). 2. Relating long resin tags of $70-120{\mu}m$ were observed in samples of all groups under SEM. We could observed hybrid layer, resin tag and many lateral branches in every group. But, we observed in group III rare lateral branched than other two group and discontinuous hybrid layer.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.2
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• pp.158-164
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• 2019

The purpose of this study was to compare the bond strength of resin-modified glass ionomer (RMGI) to dentin with saliva contamination at different stages and using different decontamination procedures. Extracted human permanent molars were embedded onto acrylic resin with the dentin surface exposed. Group I was a control group that was conditioned with polyacrylic acid (PAA). Groups II and III were contaminated with saliva before PAA conditioning and Groups IV, V, and VI were contaminated with saliva after PAA conditioning. After saliva contamination, Groups II and IV were dried, Groups III and V were rinsed and dried, and Group VI was additionally conditioned with PAA. After surface treatment, the dentin specimens were filled with RMGI. Group I showed significantly higher bond strength than the other groups. Group VI showed a significantly higher bond strength than the other saliva contaminated groups. However, there were no significant differences in the failure mode between the different groups. Saliva contamination impaired the bond strength of RMGI to dentin, regardless of when the saliva contamination occurred. Decontamination with washing and drying could not improve the shear bond strength of RMGIC. When saliva contamination occurred after PAA conditioning, additional PAA conditioning improved the shear bond strength.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.617-617
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• 2013

최근 그래핀 연구와 더불어 2차원 구조의 나노소재에 대한 관심이 급증하면서 육각형의 질화붕소(hexagonal boron nitride; h-BN) 박막(nanosheet) [1]이나 붕소 탄화질화물(boron caronitride; BCN) 박막 [2,3]과 같은 2차원 구조체에 대한 연구가 활발히 진행되고 있다. 그 중 BCN은 반금속(semimetal)인 흑연(graphite)과 절연체인 h-BN이 결합된 박막으로 원소의 구성 비율에 따라 전기적 특성을 제어할 수 있다는 장점이 있다. 따라서 다양한 나노소자로의 응용을 위한 연구가 활발히 진행되고 있다. 본 연구에서는 폴리스틸렌(polystyrene, PS)과 보레인 암모니아(borane ammonia)를 고체 소스로 이용하여 열화학기상증착법으로 BCN 박막을 SiO2 기판 위에 직접 합성하였다. SEM과 AFM 관측을 통해 합성된 BCN 박막의 두께가 약 10 nm이며, RMS roughness가 0.5~2.6 nm로 매우 낮은 것을 확인하였다. 합성과정에서 PS의 양을 조절하여 BCN 박막의 탄소의 밀도를 성공적으로 제어하였으며, 이에 따라 전기적인 특성이 제어되는 양상을 확인하였다. 또한 합성온도 변화에 따른 BCN 박막의 전기적인 특성이 제어되는 양상을 확인하였다. 추가적으로 같은 방법을 이용하여 BCN 박막을 Cu 위에서 합성하여 SiO2 기판위에 전사하였다. 합성된 BCN 박막의 구조적 특징과 화학적 조성 및 결합 상태를 투과전자현미경(transmission electron microscopy), X-선 광전자 분광법(X-ray photoelectron spectroscopy), 라만 분광법(Raman spectroscopy)을 통해 조사하였고, 이온성 용액법(ionic liquid) [4]을 이용하여 전계효과 특성을 측정하였다.

• Applied Biological Chemistry
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• v.27 no.1
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• pp.1-6
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• 1984

The lipoprotein-bound carotenoids occurred in the viscera of abalone (Haliotis discus hannai) were separated and characterized to be the mixture of fatty acid esters of lutein and free lutein. The main fatty acid components of the esters were lauric (68%) and myristic acid (17%), and indicated the characteristic pattern compared with that of triglycerides and cholesterol esters in abalone. Patterns of carotenoids from the lipoproteins were, simple and this suggested selected metabolisms of various feed-originated carotenoids found in the whole acetone extract of abalone.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.255-255
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• 2013

최근 그래핀 연구와 더불어 2차원 구조의 나노소재에 대한 관심이 급증하면서 육각형의 질화붕소(hexagonal boron nitride; h-BN) 박막(nanosheet)이나 붕소 탄화질화물(boron caronitride; BCN) 박막과 같은 2차원 구조체에 대한 연구가 활발히 진행되고 있다. 그 중 BCN은 반금속(semimetal)인 흑연(graphite)과 절연체인 h-BN이 결합된 박막으로 원소의 구성 비율에 따라 전기적 특성을 제어할 수 있다는 장점이 있다. 따라서 다양한 나노소자로의 응용을 위한 연구가 활발히 진행되고 있다. 본 연구에서는 폴리스틸렌(polystyrene, PS)과 보레인 암모니아(borane ammonia)를 고체 소스로 이용하여 열화학 기상증착법을 이용하여 BCN 박막를 SiO2 기판 위에 직접 합성하였다. SEM과 AFM 관측을 통해 합성된 BCN 박막을 확인하였으며, RMS roughness가 0.5~2.6 nm로 매우 낮은 것을 확인하였다. 합성과정에서 PS의 양을 조절하여 BCN 박막의 탄소의 밀도를 성공적으로 제어하였으며, 이에 따라 전기적인 특성이 제어되는 양상을 확인하였다. 또한 합성온도 변화에 따른 BCN 박막의 전기적인 특성이 제어되는 양상을 확인하였다. 추가적으로 같은 방법을 이용하여 BCN 박막을 Ni 위에서 합성하여 SiO2 기판위에 전사 하였다. 합성된 BCN 박막의 구조적 특징과 화학적 조성 및 결합 상태를 투과전자현미경(transmission electron microscopy), X-선 광전자 분광법(X-ray photoelectron spectroscopy)을 통해 조사하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.67-67
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• 2021

하구에서의 흐름은 하천의 담수와 바다에서부터 유입되는 염수, 조석, 파랑 등으로 인해 복잡한 흐름구조와 혼합 양상을 보인다. 특히 만 내에 하천이 있을 경우 만의 해류특성은 하구에서의 혼합과 이송에 지배적인 영향을 미치며, 하천에서부터 방류되는 입자들은 만의 해류특성 따라 만에서의 체류시간과 이송이 결정된다. 잔차류 특성에 의한 순 물질 플럭스의 방향과 조석비대칭에 따른 하구에서의 퇴적 형태들이 결정되며, 이로 인해 하구에서의 퇴적물 퇴적 및 물질의 집적 위치, 하구 인근과 만에서의 환경변화에 영향을 줄 수 있다. 따라서 만 내에서의 혼합과 입자의 이송확산, 하천 담수의 영향역 등과 같은 만과 하천의 흐름 특성을 이해하는 것은 연안 및 하구의 환경 및 관리에 중요하다. 본 연구에서는 영일만과 형산강을 대상으로 계절변화에 따른 영일만 내 흐름과 형산강 하구에서의 퇴적양상에 대해 수치모의를 통해 수행하였다. 수치모델로는 천수방정식으로 준 3차원 유동해석을 하는 Delft-3D Flow와 파랑모형인 SWAN 모델을 결합하여 형산강 하구와 영일만의 유동을 해석하였다. 상류개방경계는 형산강하구 9 km, 하류개방경계는 영일만 외해 50 km로 설정하였고, 경계조건은 대상지역의 관측소 자료와 전지구 모형자료를 결합하여 구성하였다. 또한, 라그랑쥬 입자추적모델을 통해 형산강 상류에서 유입한 입자들의 영일만 내 체류 시간과 집적 위치를 평가하였다.