• 대한치과기공학회지
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• 제29권1호
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• pp.121-131
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• 2007

A preparation process's conditions of aqueous sol which contains anatase-type nano titania particles with photocatalyic properties was established by using Yoldas process, so called, DCS(Destabilization of Colloidal Solution) process in this study. And crystal size change and phase transformation of titania particles in aqueous titania sol depending on reaction conditions was investigated by a light scattering method and XRD analysis of frozen dried powders, respectively. This sol with photo catalytic nano titania particles was used to the following hydrophilic hybrid coating film's fabrication and its properties was evaluated. Subsequently, for coating film using the above mentioned aqueous titania sol, non-aqueous titania sol was prepared without any chemical additives and its time stability according to aging time was investigate. By using the above mentioned aqueous titania sol and non-aqueous sol, a complex oxide coating sol for metal and ceramic substrate and a organic-inorganic hybrid coating sol for polymer substrate was prepared and it's hydrophilicity depending on UV irradiation conditions was evaluated. As a conclusions, the following results were obtained. (1)Aqueous titania sol The average particle size of titania in formed aqueous titania sol was distributed between 20$\sim$90nm range depending on reaction conditions. And the crystal phase of titania powders obtained by frozen drying method was changed from amorphous state to anatase and subsequently transformed to rutile crystal phase and it is attributed to concentration gradient in aqueous sol. (2)Non-aqueous titania sol Non-aqueous titania sol was prepared using methanol as a solvent and a little distilled water for hydrolysis and nitric acid as a catalyst were used. The obtained non-aqueous titania sol was stable at room temperature for 20 days. Additionally, non-aqueous titania sol with addition of chealating reagent such as acethylaceton and ethylene glycol prolonged the stability of sol by six months. (3)Complex sol and hybrid sol with super hydrophilicity The above mentioned aqueous titania sol as a main photocataylic component and non-aqueous titania sol as a binder for coating process was used to prepare a complex sol used for metal, ceramic and wood material substrate and also to prepare the organic-inorganic hybrid sol for polymer substrate such as polycarbonate and polyethylene, in which process APMS(3-Aminopropyltrimethoxysilane), GPTS(3-Glycidoxypropyl-trimethoxysilane) as a hydrophilic silane compound and HEMA(2-Hydroxyethyl methacrylate) as a forming network in hybrid coating film were used. The hybrid coating film such as prepared through this process showed a superhydrophilicity below 1$10^{\circ}$ depending on processing conditions and a pencil's hardness over 6 H.

• 한국식품영양학회지
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• 제25권3호
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• pp.521-528
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• 2012

This study was performed to develop a therapeutic diet against aging and obesity, using Yangha(Zingiber mioga R.). Before development of a therapeutic diet, we performed cell viability assay, analysis of general composition, macrominerals and antioxidantive activities of Yangha. Based on the findings from analyzing the results, mook using Yangha powder(0~20%) was processed, and tested for quality characteristics such as color values, sensory evaluation and mechanical properties. The result of cell viability assay of myoga, using liver cells, revealed that within the concentration range from 500 ${\mu}g/m{\ell}$ to 10,000 ${\mu}g/m{\ell}$, cell survivability increased in line with the concentration rate. Therefore, it will not be harmful to consume it as food. Regarding the normal substance of myoga, the water substance of myoga was 94%, which exceeds that of ginger and tumeric with 89% and 83%, respectively. As for crude protein, fat, carbon hydrates and ash, myoga contained less than the other two, which I think is due to the high water substance. Regarding the minerals, potassium had the highest contents among macrominerals of 234.74 mg%. As for the antioxidant test, hydroxy radical scavenging activity and superoxide radical scavenging activity were shown. As for the production of Yangha mook(Yangha powder levels were 0~20%) for quality characteristics, the more of the powder, the less the L, but the greater the a and b values. Also, for the material property, an increased amount of the powder, resulted in chewiness and springiness, but less gumminess in a correlated manner. However, there were no significant differences in the springiness and cohesiveness in relation to the powder. For the sensory test, jelly type ZM5 with 5% powder showed highest overall preference. According to the sensory test, based on the powder substance, the jelly with 5% powder showed the highest overall score, including preference.

• 한국결정성장학회지
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• 제27권6호
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• pp.319-326
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• 2017

본 연구에서는, IGCC(Integrated Gasification Combined Cycle: 석탄가스화 복합발전)에서 배출되는 용융 슬래그로 부터 지오폴리머를 제조하여 알칼리 활성화제의 몰농도, W/S 비(water/ solid ratio), 재령일에 따른 비중과 압축강도 등 물리적 특성을 분석함과 동시에 발포제인 Si 슬러지를 첨가하여 경량화 소재로서의 가능성을 고찰하였다. 특히 경량 지오폴리머의 강도 특성향상을 위하여 복합 활성화제 및 pre-curing 공정을 적용하였다. 단일 활성화제를 사용한 경량 지오폴리머의 압축 강도는 9.5 MPa이었으나, 복합 활성화제로 제조할 경우 2~5배 정도의 압축강도 증진 효과를 나타내었다. 더군다나, pre-curing을 실시한 경량 지오폴리머의 경우, pre-curing하지 않은 시편들에 비해 18~48 % 가량 높은 압축강도 값을 보였다. 본 연구에서 복합 활성화제와 pre-curing 공정의 도입으로 얻어진 경량 지오폴리머의 최고 압축강도는 40 MPa(3일 재령하여 밀도가 $1.83g/cm^3$인 시편)로서 시멘트 콘크리트에 필적하였다. XRD 결정상 분석과 SEM을 이용한 미세구조 분석을 통하여 지오폴리머 표면에서 C-S-H 겔(sodium silicate hydrate gel)의 모상에 꽃봉오리 모양의 zeolite 결정상이 균일하게 분포된 것을 확인할 수 있었다.

• Advances in environmental research
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• 제6권3호
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• pp.159-171
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• 2017

A successful oil well drilling depends largely on a good mud Program. During drilling, mud provides sufficient hydrostatic pressure, removes drill cuttings and cools drill bits. Mud additives are always required to provide sufficient hydrostatic pressure to ensure borehole stability. Barium Sulphate ($BaSO_4$) also known as barite is the prevalent weighting material but there is needed to develop local materials to augment the use of Barite. The present search is concerned on the early Carboniferous succession exposed in Um Bogma Formation, west central Sinai, Egypt as a new weighting agent in drilling fluids. The increases in the cost of drilling fluids and a shortage of using barite have introduced the locale dolomite as alternative weighting materials. The rheological properties of mud drilling samples weighted by local dolomite samples are being examined and investigated to know its potential to be used as a weighting material in drilling mud. Two mud samples were prepared which comprised of fresh water, caustic soda, bentonite and the weighting material. The weighting materials are added to achieve the required density. The first sample: Water-based mud with commercial barite of density between 10.00 lb/gm and 18.00 lb/gm. The second sample: Water-based mud with dolomite of density between 10.00 lb/gm and 18.00 lb/gm. These samples were analyzed and the density, rheological properties, aging of barite and dolomite and solid contents were investigated. At 10.00 lb/gm, the yield point of dolomite was $20.00lb/100ft^2$ and barite $22.00lb/100ft^2$ while the 10 second gel strength of dolomite was $30.00lb/100ft^2$ and $22.00lb/100ft^2$ for barite. Similarly, little difference was observed in plastic and apparent viscosities. At 10.00 lb/gm, the plastic and apparent viscosities of dolomite were 8.00 cp and 20.00 cp while barite was 8.00 cp and 24.00 cp. The result show that dolomite mud sample gave a little higher yield point and gel strength than barite mud sample. Therefore, dolomite has the potential to be used as weighting material in drilling mud in place of barite thereby enhancing the local content initiative of the government. When dolomite is sourced locally and used it will reduce overall mud and drilling costs.

• 한국식품영양과학회지
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• 제31권6호
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• pp.977-985
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• 2002

고추장의 품질향상을 위해 다시마와 키토산의 농도를 달리하여 첨가하고 2$0^{\circ}C$에서 24주간 숙성시키면서 효소활성도와 미생물상, 이화학적 튿성을 비교하였다. 고추장의 $\alpha$와$\beta$-amylase는 각각 다시마 2%. 키토산 01.%첨가구에서 조금 높은 활성을 보이나 산성 protease활성은 이들의 첨가농도가 증가하면 감소하였다. 효모수는 숙석 4~8주경에 $10^{5}$~$10^{6}$ CFU/g으로 증가하였고, 세균수는 키토산이나 다시마의 첨가로 감소하였다. 수분은 숙성 12주까지 서서히 증가하나 수분활성도는 감소하였고, 다시마 첨가구에서 낮았다. 점조성은 숙성 중기이후에 증가하였으며 다시마 첨가시 증가되었다. 고추장의 색도는 숙성 중 a값이 낮아졌고, 다시마 첨가량이 증가하면 a와 b값이 낮아졌다. $\Delta$E값은 고추장 숙성중 증가하나 다시마 첨가구에서 낮았다. 적정산도는 4주 이후에 감소되었으며, 키토산의 첨가농도가 높을수록 낮았다. 다시마와 키토산의 농도가 증가할수록 숙성 후기의 아미노태 질소는 많았고, 암모니아태 질소는 키토산 첨가구에서 낮았다. 환원당은 숙성 4~8주에 급격히 증가하였으며, 키토산 첨가량이 증가할수록 많았다. 알콜은 숙성 12~16주까지 증가되었으며, 다시마 첨가구에서 낮았다. 고추장의 맛과 색, 전반적인 기호도는 키토산 01.% 첨가시 좋았고, 다시마는 첨가량이 증가할수록 맛, 색, 향기 모두 낮은 판정을 받았다. 향기 모두 낮은 판정을 받았다.

• 한국식품영양과학회지
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• 제44권12호
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• pp.1799-1805
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• 2015

쌀식초(rice vinegar, RV)는 쌀, 찹쌀, 현미 등을 주원료로 발효되며, 쌀을 주식으로 하는 아시아 지역에서 조미료로 이용되어 왔다. 본 연구에서는 한국산(KRV1~4), 중국산(CRV1~2), 일본산(JRV1~4) 시판 천연발효 쌀식초 10종을 구입하여 이들의 품질을 비교하였다. 식초의 적정산도에 대한 나라별 기준은 한국(식품공전) 4~29%, 중국(GB) 3.5% 이상, 일본(JAS) 4.2% 이상으로 10종의 시료는 모두 이 기준을 만족하였고, KRV(5.07~6.27%)가 CRV(4.67~4.84%) 및 JRV(4.64~4.84%)에 비해 유의적으로 높은 값을 나타내었다. 쌀식초의 주요 유기산으로 acetic acid와 succinic acid를 포함한 6종이 분석되었고 유리아미노산으로 30종이 분석되었으며, 한국산의 경우 alanine, 중국산의 경우 phenylalanine과 aspartic acid, 일본산의 경우 leucine과 alanine이 주요 성분으로 확인되었다. 한편 생리활성물질인 ${\gamma}-aminobutyric$ acid는 KRV1에서 유의적으로 높게 분석되었다. 총 폴리페놀은 KRV1에서 가장 높은 함량을 나타내었고, 이 시료의 DPPH 및 ABTS 라디칼 소거 활성 또한 유의적으로 높게 확인되었다. 천연발효 쌀식초의 이화학적 품질은 원료의 종류 및 함량, 발효방법, 숙성 여부에 따라 차이를 나타내었고, 현미를 사용하여 1년 이상 정치발효 한 KRV1에서 가장 높은 아미노산 함량 및 항산화 활성이 확인되었다.

• 공업화학
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• 제23권5호
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• pp.467-473
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• 2012

본 연구에서는 레시틴, 에탄올, 오일, Arlacel 60 (sorbitan monostearate) 등을 주성분으로 하고, 최근 화장품과 식품의 원료로서 각광을 받고 있는 피부의 노화방지용 항산화물질인 코엔자임 Q10 (CoQ10)를 기능성 원료로 함유하는 나노 에멀젼을 제조하고자 하였다. 에멀젼 제조방법으로는 반전유화법(phase inversion emulsion method)과 초음파를 이용한 기계적 방법을 사용하였으며, 이 때 에탄올과 레시틴의 영향과 시간의 경과에 따른 안정성과 그 밖의 각종 변수들이 미치는 영향을 알아보고자 하였다. 이를 위하여 입자의 크기, 제타전위, 에멀젼의 형태와 같은 물리적 특성들을 측정해 보았다. 최소크기의 나노에멀젼을 형성하기 위한 CoQ10의 최적 배합농도는 0.8% 정도였고, 계면활성제로서 Arlacel 60 농도에 따른 입자크기의 영향을 보면 3% 정도에서 100 nm 크기의 에멀젼 입자들을 얻을 수 있었다. 본 연구에서의 사용한 최적의 계면활성제 농도범위(2% 이상)에서는 7일 정도가 지난 시점까지 Ostwald ripening 에 따른 입자의 크기 변화가 없었다. 장시간의 경과에 따른 실험을 보면 에멀젼들은 실온에서 270일이 지난 상태에서도 115 nm로 10% 정도만의 크기 변화를 보여 비교적 안정된 상태로 에멀젼을 유지함을 알 수 있었으며, 제타전위 측정으로 시간의 경과에 따른 입자크기의 변화는 응집(flocculation)에 기인한 것으로 판단된다.

• Restorative Dentistry and Endodontics
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• 제17권2호
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• pp.307-330
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• 1992

The aim of this study was to investigate the physical properties of visible light curing Glass Ionomer cement for restorative esthetic filling. The control group was the autopolymerizing GC Fuji II Glass Ionomer cement (2.2: 1 P/L ratio) and the experimental groups were made by following procedure. To induce the polymerization by visible light, the powder of GC Fuji II GI cement and the liquid of Vitrabond for base & liner were mixed in an amalgam capsule with 2.5:1, 3.0:1, 3.5:1 P/L ratio (% wt/wt). After fabrication of specimens, compressive strength, fracture toughness ($K_{IC}$) Scanning Electron Microscope and X-ray Diffraction, water-leachable content, marginal leakage and surface roughness were studied. The results were as follows: 1. Only experimental No. 1 group (visible light curing) showed less compressive strength than control group 1 hour after curing. Strength was increased with aging in all groups, so the compressive strength of light curing groups was no less than that of autopolymerizing group after 3 weeks. 2. Experimental No.3 group (visible light curing) was inferior to No.2 group (visible light curing) in fracture resistance but light curing groups were more resistant to fracture than autopolymerizing group and showed ductile fracture pattern as compared with the brittle fracture pattern of autopolymerizing group. 3. From scanning electron microscopic image, various sized unreacted powder particles, surrounded by silica gel, were embedded in polysalt matrix. Light curing groups showed little crack and more dense unreacted particles than autopolymerizing group. 4. From X-ray diffraction analysis, GC Fuji II Glass Ionomer cement powder and all groups showed glassy appearance but light curing groups seemed to be more intensive in crystaline than autopolymerizing group. S. The most significant dissolution was shown in early setting period in all group. Light curing groups were dissolved less than autopolymerizing group. 6. Marginal leakage was not different significantly in case of cavity margin composed of same tooth structure (ex. only enamel margin, only dentin margin) but much more leakage was shown in dentin/cementum margin than enamel margin. In only case of only enamel margin, light curing groups were superior to autopolymerizing group. 7. All groups showed relatively smooth surface, which irregularity was less than $1{\mu}m$. Light curing groups were smoother than autopolymerizing group.

• Restorative Dentistry and Endodontics
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• 제22권2호
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• pp.505-518
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• 1997

The objective of this investigation was to compare the effects of water storage on the aspect of hardness and diametral tensile strengths of four hybrid glass ionomer cements(two compomers and two resin-reinforced glass ionomers) with a resin composite material. One composite resin(Degufill Ultra), two compomers(Dyract, Compoglass Cavifil), and two resin-reinforced glass ionomers(Fuji Duet, Vitremer) were used in this study. Cylindrical specimens were prepared and stored at $36{\pm}1^{\circ}C$ in distilled water for 10 minutes after set, and then tested on an Instron testing machine(No.4467) at 1.0 mm/min displacement rate. Vicker's hardness and diametral tensile strengths as time elapsed were measured after aging in water for 10 minutes, 1 hour, 3 hours, 1 day, 3 days, 5 days and 7 days at $36{\pm}1^{\circ}C$. During the test of diametral tensile strength, stress-strain curves were obtained, from which the compressive modulus were calculated and compared. The structure of four set glass ionomer cement mass was observed on SEM(Hitachi, S-2300) after being etched with 9.6% hydrofluoric acid for 1 minute. The results were as follows; 1. The hardness of the experimental group(compomer and the resin reinforced glass ionomer cement) did not exceed the value of control group(Degufill Ultra). 2. Vicker's hardness of the Fuji Duet tended to increase succeedingly, Dyract was decreased after 3 hours in water, and Vitremer was the lowest. 3. The control group(Degufill Ultra) presented progressively on increased diametral tensile strength with time, Fuji Duet were decreased after 3 days, Compoglass Cavifil and Vitremer were decreased after 5 days in water storage. 4. Compressive modulus of the control group(Degufill Ultra) and Dyract were increased sharply timely, Fuji Duet and Vitremer were increased smoothly by lapse of time in water. Fuji Duet were stronger than Vitremer. On the other hand, Vitremer exhibited the lowest toughness. 5. The microstructure of compomer was similar with that of the composite resin(Degufill Ultra), and the fillers in resin-reinforced glass ionomer cements were noticed. It can be concluded that mechanical properties of hybrid glass ionomer cements is weaker than composite resin, and that the compomers or the resin-reinforced glass ionomers can not substitute the composite resins. A plenty of considerations should be done on the application of them to the area under the loading and high wear has a little adverse effect on the mechanical properties on the water storage for 7 days. The further research should be needed to confirm the advantage of the compomer.

• 한국식품과학회지
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• 제25권3호
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• pp.252-257
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• 1993

본 연구는 한우 9두를 E.S. 처리하여 비처리구와 물리화학적 차이를 비교함으로써 전기자극이 한우의 육질개선 효과에 미치는 영향을 살펴보기 위해 실시하였다. 일반적인 방법으로 도축을 실시한 후 45분 이내에 400V/60Herz로 1분간 전기자극 후 E.S. 처리구와 대조구에서 각 근육별로 시료를 취하여 $5^{\circ}C$와 $15^{\circ}C$로 구분하여 3일간 저장하며 실험한 결과는 다음과 같다. 도체에서의 lactate의 변화는 초기 E.S. 처리구가 대조구에 비해 2배 이상 증가하였다. 또한 E.S. 처리 직후부터 저장 4시간까지 E.S. 처리구가 대조구에 비해 근육내 lactate의 급속한 증가를 보이고 있으며(p<0.01), 직후 $6{\sim}8$시간까지 대조구에 비해 E.S. 처리구의 증가속도가 높았으나(p<0.05), 12시간 이후에는 완만하게 증가하여 24시간 이후에는 두 처리구 공히 거의 비슷한 경향을 보였고, 그에 따라 pH는 E.S. 처리구에서 고도의 유의성을 보이며 감소하였다. ATP는 E.S. 처리구가 급격한 감소를 보이면서, 저장 12시간까지 거의 분해되는 것으로 나타났으며, 저장 6시간에 $5^{\circ}C$에서 p<0.05의 유의차를 보인데 반하여 $15^{\circ}C$에서는 p<0.01로 고도의 유의차를 보이며 감소하였다. Shear force value는 전기자극 직후에 E.S. 처리구가 대체로 높았으나, 저장후 1일, 3일에는 E.S. 처리육이 연도가 개선되어(p<0.01) 전기자극에 의해 한 우육의 숙성이 효과적으로 촉진되었음을 확인하였다.