• Journal of Adhesion and Interface
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• v.10 no.4
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• pp.174-181
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• 2009

The viscosity for hi-solid pressure sensitive adhesive to improve water soluble low viscosity pressure sensitive adhesive polymerized using seeded polymerization. While seed binder polymerizing it produces an optimum polymerization condition, and acrylic acid and seed binder concentration changed were measurement of viscosity variation and adhesive power at the substrate (SUS420J) as flowing results. In adhesive polymerization, seed binder concentration 7 wt%/monomer was recovered 60% of solid content, 2,100 cps of low viscosity and clear adhesive film. When acrylic acid content was 4 wt%/monomer, it was turned excellent adhesive power and holding power.

• Polymer(Korea)
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• v.28 no.3
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• pp.273-280
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• 2004

Acrylic resins (ethyl methacrylate-2-hydroxypropyl methacrylate-n-butyl acrylate-acrylic acid EHBCs) containing 80％ of solid were synthesized. Then, high-solid coatings (ethyl methacrylate-2-hydroxypropyl methacrylate-n-butyl acrylate-acrylic acid/hexamethylene diisocyanate-biuret : EHBCNs) were prepared by curing of the acrylic resin with curing agent hexamethylene diisocyanate-biuret at room temperature. The cure time of prepared coatings EHBCN-4 (EHBC-4 : $T_{g}$ = $0^{\circ}C$) and EHBCN-7 (EHBC-7 : $T_{g}$ = 3$0^{\circ}C$), measured by rigid-body pendulum method, was recorded 6.2 hours and 4.5 hours, respectively. Dynamic viscoelastic experiment revealed the glass transition temperature of EHBCN-4 and EHBCN-7 to be $14^{\circ}C$ and $39^{\circ}C$, respectively. It was found that the adhesion and flexural properties among various properties of coatings were enhanced by the incorporation of caprolactone acrylate monomer into the acrylic resins.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.386-389
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• 2007

본 논문은 $TiO_2$(Degussa, P-25), 바인더(A-9540) 그리고 용제의 배합비율을 바꾸어 코팅액을 제조하여 금속판에 코팅한 후, 고농도의 IPA를 주입하여 분해효율을 고찰하였다. 고형분 함량 비율 변화에서는 $TiO_2$ 함량은 증가하고 바인더가 감소할수록 좋은 효율을 보였고, 용제는 ethanol과 MEK 두 가지 중에 MEK의 분해효율이 좋았다. 용제(MEK)함량 비율 변화에서는 일정량의 용제가 있을 경우 분해효율이 좋았고, 용제함량이 낮아질 경우 코팅액 점도가 높아지고 건조 후에는 표면이 갈라지는 현상을 보였다. 결국, 용제함량 비율 변화는 바인더 함량 실험에도 영향을 주어 1.75:0.25:10일 때 가장 좋은 분해효율을 보였다.

• Journal of the Korean Applied Science and Technology
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• v.38 no.2
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• pp.476-487
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• 2021

To prepare acrylic resin coatings containing 70% of solids, we used n-butyl methacrylate(BMA), methyl methacrylate(MMA), 2-hydroxyethyl methacrylate(2-HEMA), and acetoacetoxyethyl acrylate(AAEA), caprolactone acrylate(CLA) as raw materials, the glass transition temperature(T_g) of acrylic copolymer was adjusted around 50 ℃. The viscosity and molecular weight of the acrylic resins was increased with increasing OH values. Di-tert-amyl peroxide was found to be the suitable initiator to get high-solids acrylic resins. The optimum reaction conditions found in the study are 5 wt% of initiator, 4 wt% of chain transfer agent, 4 hrs of dropping time, and 140 ℃ of reaction temperature. The structure of the synthesized resins were characterized by FT-IR and ¹H-NMR spectroscopy. Number average molecular weight of 1900~2600 and molecular wight distribution of 1.4~2.1 were obtained. Crosslinked acrylic urethane clear coatings were obtained by curing reaction between the synthesized acrylic resins and hexamethylene diisocyanate trimer(Desmodur N-3300), the equivalent ratio of NCO/OH was 1.2/1.0. The physical properties from the following studies were carried out: viscosity(Zahn cup #2), adhesion, drying time, pot-life, pensil hardness, and 60° specular gloss. Various properties of the acrylic urethane clear coatings were also evaluated on the coating specimens. Adhesion property to a substrate, drying time, pot-life, pencil hardness, and 60° specular gloss of prepared paint showed quite good properties. Futhermore, prepared paint containing 10% of CLA showed quite good properties for adhesion, low viscosity and high hardness.

• Journal of the Korean Electrochemical Society
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• v.19 no.2
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• pp.50-56
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• 2016

Spherical lithium manganese oxide spinel, $Li_{1.10}Mn_{1.86}Al_{0.02}Mg_{0.02}O_4$ was prepared by wet-milling, spray-drying, and sintering process. In the spray-drying process, solid content in slurry was varied from 20 to 30 wt%. In the sintering process, the precursors have been sintered under air or $O_2$ atmosphere. While the as-prepared samples exhibit excellent electrochemical properties at room temperature, the discharge voltage profiles at 5.0C are very different one from another. The origin for the difference especially at initial state of discharge is oxygen defect. The sample prepared in air has larger capacity related to the plateau at 3.3 V (vs. $Li/Li^+$) which is caused by the oxygen defects than the one prepared in $O_2$. The difference of discharge voltage profiles especially at the final state of discharge comes from different diffusion rate of $Li^+$ ions. The sample prepared from 30 wt% solid content of slurry shows twice higher diffusion rate than the samples prepared from 20 wt% solid content, which is attributed to better compactness between primary particles for the sample prepared from 30wt % solid content than the one prepared by 20 wt%.

• Food Science and Preservation
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• v.23 no.5
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• pp.696-703
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• 2016

The purpose of this study was to determine the optimum re-extraction conditions of ethanol from catechin in Korean green tea (Camellia sinensis L.) using response surface methodology (RSM). The experiments were carried out according to a five level and two variable central composite design (CCD). The two independent variables were solvent ratio to sample content (1, 4, 7, 10, 13 mL/g) and extraction temperature (-20, -10, 0, 10, $20^{\circ}C$) on the dependent variables including yield, epigallocatechin (EGC), epicathchin (EC), epigallocatechingallate (EGCG), epicatechingallate (ECG), total catechin and caffeine. ANOVA results showed that Coefficients of determination ($R^2$) of estimated models for dependent variables were ranged from 0.9054~0.9778, while $R^2$ of caffeine were estimated 0.8770. The optimum ranges for the maximized extraction including yield, EGC, EC, EGCG, ECG, caffeine and total catechin were 4.5~7.5 mL/g in ratio of ethanol to sample and $-8{\sim}8^{\circ}C$ in extraction temperature. The actual values of yield, EGC, EC, EGCG, ECG, caffeine and total catechin, respectively, at the optimized conditions were 35.02%, 13.31%, 3.978%, 19.11%, 4.29%, 5.30% and 40.68%.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.10a
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• pp.107-108
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• 2011

• Food Science and Preservation
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• v.6 no.4
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• pp.380-385
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• 1999

Four cultivar of astringent persimmon(Diospyros kaki L. Cheongdobansi, Sagkoksi, Gojongsi, and Hachiya) were evaluated for quality during 160 days storage in condition of air, 12%CO$_2$+3%CO$_2$, and 16%CO$_2$+ 3%CO$_2$at 0∼2$^{\circ}C$. In the fruits of Cheongdobansi, Sagkoksi, and Gojongsi cultivar, the soluble solids content did not change significantly during storage among treatment, but in the fruits of Hachiya cultivar it decreased during storage in the codition of high CO$_2$concentration. Fruits of Cheongdobansi and Sagkoksi, which were stored in higher CO$_2$concentration, had firmer hardness, less weight loss and decay, showed greater rentention of initial peel color, maintained best qulity than air-stored fruit, but had high tannin contents. And it was necessory to remove astringency for edible fruits.

• Journal of Biosystems Engineering
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• v.23 no.1
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• pp.31-48
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• 1998

가축분뇨, 음식쓰레기 둥의 유기성 고형 폐기물의 퇴비화처리 과정의 성능 향상과 암모니아 가스 발생을 저감화 하려는 연구의 일환으로서 파이로트 규모의 원통형 회분식 분해조 및 숙성조를 설계, 제작하여 퇴비화 성능과 탈취 효과를 분석하였다. 고형퇴비화 처리에 미치는 주요요인은 초기재료의 수분, 탄질비, 수소이온농도, 발효온도 및 통기조건 등이다. 돈분에 부자재인 톱밥을 혼합하여 초기 재료의 수분, 탄질비, 수소이온농도 등을 동일한 재료로서 같은 수준에 유지하고 연속통기와 간헐통기 방식으로 퇴비화하는 동안에 분해 및 숙성단계의 부위별 발효온도의 변화, 산소흡수 및 탄산가스 배출농도의 변동, 평균통기량, 재료의 평균온도 변화, 암모니아가스 배출농도의 변화 등을 분해 및 숙성 전기간을 통해 측정하고 초기재료와 숙성재료의 주요 이화학적 성분을 분석하여 퇴비화 성능과 회비 탈취 효율을 비교하였다. 주요 연구결과는 다음과 같다. 1. 숙성과정 8일 이후의 암모니아가스 탈취효율은 연속통기법이 90%이고, 간헐통기법이 70%였으며, 분해 및 숙성과정의 발효온도, 탄산가스 발생, 암모니아가스 배출농도 및 숙성회비의 성분 둥의 결과로서 판단할 때 에 퇴비 화 소요기 간은 6주간이었다. 2. 탄산가스 배출농도 변화로서 간헐통기 퇴비화 방식은 연속통기법에 비하여 분해과정이 7일 정도 빠르고, 숙성과정이 10일 정도 단축되었으며 암모니아가스 농도도 적게 나타나고 있었다. 3. 퇴비화 분해과정이 지난 후 숙성과정 도입단계에서 퇴비재료의 혼합 교반에 따른 재료의 고온상승으로 인한 암모니아가스의 고농도화 현상의 억제대책이 필요하다고 판단되었다.

• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.776-783
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• 1997

Response surface methodology was applied to determine the optimum roasting conditions (roasting temperature and time) for the high-quality Polygonatum odoratum tea which has been roasting with a traditional means. As quality criteria of Polygonatum odoratum tea, water-soluble solids, browning color, total phenolic compounds and electron-donating ability were proportionally increased with increased temperature and time of roasting conditions up to around $145^{\circ}C$ and 55 min, respectively, while they were decreased under the extended-roasting conditions. The optimum roasting temperature and time based on the organoleptic overall acceptability were $146^{\circ}C$ and 52 min, respectively. On the basis of superimposed contour maps for the tea characteristics, the optimum range of roasting conditions were $135{\sim}140^{\circ}C$ and $58{\sim}64$ min. Predicted values at the optimum conditions $(137^{\circ}C,\;60\;min)$ were in good agreement with experimental values.