• 대한치과보철학회지
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• 제37권6호
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• pp.809-818
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• 1999

This study was performed to evaluate the tensile bond strength and modulus of elasticity of three permanent soft denture liners (Molloplast $B^{(R)}$, Ufi Gel $C^{(R)},\;Tokuyama^{(R)}$) before and after thermocycling. And their water sorption were also evaluated. Each soft denture liner was bonded to PMMA denture base resin blocks and the tensile bond strength and modulus of elasticity were measured by using universal testing machine. For the water sorption, weight measured after immersion of sea denture liners in $37{\pm}1^{\circ}C$ water bath for 4 weeks. The results were as follows : 1. Molloplast $B^{(R)}$ had the highest tensile bond strength, while Tokuyama had the lowest tensile bond strength. There was no significant difference between $Tokuyama^{(R)}$ and Molloplast $B^{(R)}$ in the both nonthermocycling and thermocycling. There was significant difference in tensile strength of $Tokuyama^{(R)}$ before and after thermocycling(p<0.05). 2. For the modulus of elasticity, there was no significant difference between Ufi Gel $C^{(R)}\;and\;Tokuyama^{(R)}$ in the both nonthermocycling and thermocycling. There was significant difference in modulus of elasticity of $Tokuyama^{(R)}$ before and after thermocycling(p<0.05). 3 The failure modes of Molloplast $B^{(R)}$ and Ufi Gel $C^{(R)}$ were mainley adhesive type and that of $Tokuyama^{(R)}$ was mainly mixed type in case of nonthermocycling and cohesive type after thermocycling. 4. The water sorption of each soft liners was within ${\pm}2%$ in times (p<0.05) but. there was no significant difference among the soft liners in times.

• Journal of the Korean Wood Science and Technology
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• 제30권3호
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• pp.1-11
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• 2002

This study was conducted to investigate the effects of reaction pH conditions and hardener types on the reactivity, chemical structure and adhesion performance of UF resins. Three different reaction pH conditions, such as traditional alkaline-acid (7.5 → 4.5), weak acid (4.5), and strong acid (1.0), were used to synthesize UF resins which were cured by adding three different hardeners (ammonium chloride, ammonium citrate, and zinc nitrate) to measure adhesion strength. Fourier transform infrared (FT-IR) and carbon-13 nuclear magnetic resonance (¹³C-NMR) spectroscopies were employed to study chemical structure of the resin prepared under three different reaction pH conditions. Adhesion strength of the resins cured with three different hardeners was determined with lap shear specimens in tension. The gel time of UF resins decreased with an increasing in the amount of both ammonium chloride and ammonium citrate added in the resins. However, the gel time increased for zinc nitrate. Both FT-IR and ¹³C-NMR spectroscopies showed that the strong reaction pH condition produce uronic structures in UF resin, while both alkaline-acid and weak acid conditions produce quite similar chemical species in the resins. The maximum adhesion strength was occurred with the resin prepared under strong acid pH condition. However, this study indicated that the weak acid reaction condition provide a balance between increasing resin reactivity and improving adhesion strength of UF resin. The measurement of formaldehyde emission from the panels bonded with the UF resins prepared is planned for future work.

• 한국축산식품학회지
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• 제30권5호
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• pp.746-754
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• 2010

Response surface methodology was adopted to model and optimize the effects of microbial transglutaminase (TG) and calcium alginate (CA) systems of various ratios on the gelation characteristics of porcine myofibrillar protein (MP) at various salt levels. The CA system consisting of sodium alginate (SA), calcium carbonate (CC) and glucono-$\delta$-lactone (GdL) showed no remarkable changes in the salt-soluble fraction, and only minor effects on electrostatic interactions were observed. Increasing CA concentration caused acid-induced hydrophobic interactions in MPs, resulting in increased MP gel strength. The TG system, containing TG and sodium caseinate (SC), induced cold-set MP gelation by formation of covalent bonding. The main advantage of the combined system was a higher cooking yield when the MP gel was heated. These results indicated that 0.7% TG combined with 0.8% CA system can form a viscoelastic MP gel, regardless of salt levels.

• 한국세라믹학회지
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• 제36권11호
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• pp.1189-1197
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• 1999

Low-density silica gel monolith was synthesized at ambient pressure by surface modification with TMCS and sub-sequent heat treatment. The mechanical thermal and optical properties of gel were studied. Compressive strength and modulus of compression of 350$^{\circ}C$-heated gel with the density of 0.24g/cm3 were 250kPa and 0.2MPa respectively. The thermal conductivity of silica gels synthesized at ambient pressure exhibited 0.02 W/m$.$K for the density of 0.24g/cm3 which is similar to that of the gel via supercritical drying and their main thermal transfer mechanism is considered to be solid and radiation conduction at room temperature. Ambient-dried silica gels were transparent blue showing about 60% of transmittance in the wavelength of 1500-2100nm and typical absorption bands of existing bonds under heat treatment at 350$^{\circ}C$. Medium scale monolity(${\Phi}$=50mm) at ambient pressure could be successfully prepared through total 5-month process period.

• Elastomers and Composites
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• 제54권3호
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• pp.247-251
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• 2019

Two different urethane acrylates (mono-acrylate and di-acrylate) were used to prepare unsaturated polyester-based hybrid gel-coats. The physical properties and surface characteristics of these gel-coats were investigated on the basis of the content and type of urethane acrylate. The set-to-touch time increased and the physical properties (surface hardness and tensile strength) decreased with an increase in the urethane acrylate content. However, the type of urethane acrylate did not affect these parameters. It was found that the optimal urethane acrylate content for the application of unsaturated polyester-based hybrid gel-coats is ~10 wt%.

• 대한치과교정학회지
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• 제36권6호
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• pp.451-464
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• 2006

본 연구는 항 교정장치의 개발에 도움이 되고자 이산화티탄 광촉매의 코팅 시 안정적이고 효과적인 방법을 찾기 위하여 시행되었다. 시판되고 있는 교정용 와이어와 브라켓에 sol-gel법, CVD (Chemical Vapor Deposition)법 및 PE-CVD (Plasma Enhanced-CVD)법으로 이산화티탄을 각각 코팅한 다음 각 방법으로 코팅된 이산화티탄 박막의 특성을 알아보고자 주사전자현미경을 이용하여 각 시편의 코팅박막 표면의 거칠기를 관찰하였고 adhesive tape pull test를 이용하여 코팅박막의 접착강도를 측정하였다. 메틸렌블루용액에 각 시편을 침지시킨 후 시간경과에 따른 메틸렌블루용액의 농도변화 측정을 통해 코팅박막의 분해능을 평가하였으며 불화나트륨 용액에 각 시편을 침지시킨 후 주사전자현미경을 이용하여 표면부식 정도를 관찰함으로써 불소화합물에 대한 내부식성을 평가하여 다음과 같은 결과를 얻었다. 코팅박막의 표면은 CVD법 및 PE-CVD법이 sol-gel법이나 코팅되지 않은 시편에 비해 더 매끄러웠다. 코팅박막의 접착강도는 PE-CVD법이 가장 높았고, CVD법, sol-gel법의 순으로 낮게 나타났다. 코팅박막의 메틸렌블루 분해능은 PE-CVD법이 가장 높았고, CVD법, sol-gel법의 순으로 낮게 나타났다. 코팅박막의 불소화합물에 대한 내부식성은 CVD법 및 PE-CVD법이 sol-gel법에 비해 높게 나타났다. 이상의 결과는 교정용 와이어 및 브라켓의 이산화티탄 광촉매 코팅 시 CVD법 및 PE-CVD법이 sol-gel법보다 적절한 방법임을 시사하였다.

• 한국축산식품학회지
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• 제26권1호
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• pp.20-27
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• 2006

돈육을 이용한 수리미 유사물 제조시 첨가되는 NaCl 함량이 돈육 수리미의 젤 특성에 미치는 영향을 알아된 결과, NaCl의 첨가량이 증가함에 따라 젤 강도는 높아지지만, pH와 수분함량은 낮아지는 것으로 나타났다. 젤의 색깔은 첨가되는 NaCl의 함량이 $2{\sim}3%$일 때 선명하면서 밝은 것으로 나타났고, 4% 첨가되었을 때에는 황색토가 증가하여 색상이 어두워지는 것으로 나타났다. 젤의 미세구조를 관찰한 결과, NaCl의 첨가량이 증가함에 따라 염용성 단백질의 용해도가 증가하여 단백질 사이의 결합이 조밀하게 이루어지는 것으로 나타났으며, 이와 같은 이유로 인해 수분함량은 감소하지만 젤의 강도는 높아지는 것으로 나타났다. 관능평가에서 2% NaCl 첨가된 돈육 수리미의 색깔이 선명하면서 밝은 것으로 나타났고 전체적인 기호성도 우수한 것으로 평가되었다.

• 한국식품과학회지
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• 제17권5호
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• pp.340-344
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• 1985

본(本) 연구(硏究)에서는 한천(寒天)의 조단백질(粗蛋白質). 회분(灰分)의 제거방법(除去方法) 및 gel강도(强度)에 미치는 영향(影響)을 검토(檢討)하였다. 조단백질(粗蛋白質) 및 회분(灰分)의 제거방법(除去方法)으로서 Trichloroacetic acid(TCA) 와 Perchloric acid(PCA)의 첨가처리(添加處理) 및 수침법(水浸法)을 사용(使用) 하였으며 그 결과(結果)는 다음과 같다. 조단백질(粗蛋白質) 제거공정(除去工程)에서 단백질(蛋白質) 침전제(沈澱劑)로는 PCA 가 TCA보다 더 효율적(效率的)이었다. 0.01% PCA 첨가시(添加時) 조단백질(粗蛋白質) 함량(含量)은 4.0%에서 1.0%로 감소(減少)하였고, gel 강도(强度)는 원료한천(原料寒天) 220g/$cm^2$에 대하여 402g/$cm^2$로 증가(增加)하였다. 회분제거공정(灰分除去工程)을 12시간(時間) 수침상태(水浸狀態)로 진탕함으로서 회분(灰分)이 8.7%에서 2.7%로 감소(減少)하였고 gel강도(强度)는 원료한천(原料寒天) 22/$cm^2$에 대해 530g/$cm^2$로 증가(增加)하였다. 그러나 회분함량(灰分含量)의 변화(變化)가 3% 미만에서는 gel강도(强度)에 미치는 영향(影響)이 거의 없었다.

• 한국수산과학회지
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• 제36권3호
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• pp.198-203
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• 2003

Heat-induced surimi gels were prepared using various concentration of ATC as a additives and calcium agent. Regardless of various concentration of ATC, there were no difference the moisture $(80.4-81.2\%)\;and\;crude\;ash\;(1.4-1.\5%)$ contents. The pH of heat-induced surimi gels were decreased 7.16 to 7.04 depend on increasing ATC concentration. The whiteness, breaking force and gel strength of $0.09\%$surimi gel were improved significantly difference (p<0.05). Sensory evaluation on texture and whiteness were also similar to determination by color and texture meters. In mineral content of heat-induced surimi gel calcium content was increased 26 to 54 mg/100g depend on increasing ATC concentration, while phosphorus content was not change. The optimal concentration of ATC for preparation of high quality heat-induced surimi gel was $0.09\%$. The shelf-life of heat-induced surimi gel did not extend by addition of $0.09\%$ ATC.

• 한국식품과학회지
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• 제24권1호
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• pp.70-73
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• 1992

옥수수 전분을 하이드록시프로필화 및 가교화시켜 변성 전분을 제조한 후 DSC, Amylograph 등을 이용하여 호화특성을 연구하고 호화액의 gel 특성을 조사하였다. 하이드록시프로필화에 의하여 옥수수 전분의 호화온도는 크게 떨어졌으며 가교화만을 시킨 전분은 호화온도가 약간 상승하였으며 호화엔탈피는 약간 감소하였다. 하이드록시프로필화와 가교화를 동시에 시켰을 때는 호화온도가 크게 떨어져 하이드록시프로필화만 시킨 것보다는 약간 높았으나 팽윤이 억제되었고 gel 조직강도는 증가하였다.