• Applied Biological Chemistry
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• v.51 no.1
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• pp.84-87
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• 2008

In this research, we screened for glucosyltransferase (GTase) inhibitors that effectively prevent the dental caries from 420 kinds of boiled water extracts of herbs and wild plants and searched for GTase inhibitory activities. Among them, 13 kinds of hot water extracts had high GTase inhibitory activities and especially, we focused on Foeniculum vulgare which showed the highest inhibitory activity on GTase. The boiled water extract of F. vulgare was stable at high temperature and showed as a mixed type of competitive and uncompetitive inhibition kinetic behavior. It did not have antibacterial effect on Streptococcus mutans and had inhibitory activity on GTase. Specially, in the clinical trial, the group treated by boiled water extract of F. vulgare showed more decrease of plague index at 4.8 point than untreated group. These results suggested that boiled water extract of F. vulgare can effectively suppress the plague formation as it inhibits the GTase activity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.160-166
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• 2018

The worldwide semi-conductor market has been growing for a long time. Manufacturing lines of semi-conductors need to handle several types of toxic gases. In particular, they need to be controlled accurately in real time. This type of toxic gas control system consists of many different kinds of parts, e.g., fittings, valves, tubes, filters, and regulators. These parts obviously need to be manufactured precisely and be corrosion resistant because they have to control high pressure gases for long periods without any leakage. For this, surface machining and hardening technologies of the metal block and metal gasket need to be studied. This type of study depends on various factors, such as geometric shapes, part materials, surface hardening method, and gas pressures. This paper presents strong concerns on a series of simulation processes regarding the differences between the inlet and outlet pressures considering several different fluid velocity, tube diameters, and V-angles. Indeed, this study will very helpful to determine the important design factors as well as precisely manufacture these parts. The EP (Electrolytic Polishing) process was used to obtain cleaner surfaces, and hardness tests were carried out after the EP process.

• Polymer(Korea)
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• v.29 no.5
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• pp.440-444
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• 2005

An increase in the surface area of drugs by reducing particle sizes from microns to nanometers has been known as an efficient method to improve the bioavailability of water-insoluble drugs. To prevent drug nanoparticles from aggregation during the processes of drug formulation, a limited number of pharmaceutical inactive ingredients such as hydroxypropyl cellulose has been employed as stabilizers or dispersants. In this study, copolymers of hydrophilic and hydrophobic amino acids were synthesized by the ring opening polymerization of their N-carboxyanhydride monomers and evaluated as novel candidates to stabilize the nanoparticles of a water insoluble drug, naproxen. Naproxen nanoparticles stabilized by synthesized amino acid copolymers were successfully prepared in the size of $200\~500nm$ in 60 min by a wet comminution process. Particle size analysis showed that the effective stabilization performance of copolymers required the hydrophobic moiety content to be higher than $10 mol\%$. However, the molecular weight and morphology of copolymers was not the critical parameters in determining the particle size reduction. Their particle size was found to be stable up to 14 days without significant aggregation.

• Polymer(Korea)
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• v.28 no.3
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• pp.239-244
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• 2004

Effect of lubricants on the rheological and thermal properties of poly(butylene terephthalate) [PBT] were investigated. Calcium stearate and adipic acid glycol polyester (AhGP) were used as processing lubricants for PBT. Decrease of melt viscosity was accomplished by the addition of 1 wt％ of lubricants. It was understood that melt viscosity was affected by the enhancement of chain mobility of PBT with AhGP as an internal lubricant as well as the lubricity on processing equipment developed by calcium stearate as an external lubricant. Lubricants also influenced chain scission of PBT which caused the viscosity drop as well. In addition, lubricant is resulted in the lowering of thermal stability, however, this might be minimized by adding less than 3 wt％ of calcium stearate as a lubricant. As a consequence, calcium stearate as an external lubricant is more effective to control the melt viscosity of PBT with minimizing of chain scission and thermal instability in PBT.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.113-119
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• 2013

Despite rapid changes in the structure of industry, manufacturing remains a key industry for economic progress, promotion of trade, increased employment, and the creation of new industries. Production technologies are essential for strengthening the competitiveness of small- and medium-sized manufacturing industries. However, it is very difficult to standardize and systematically propagate production technology from an experienced worker to an inexperienced worker because these technologies are generally improved by the skilled people in a workshop. In this study, we introduce a Web-based platform system consisting of a knowledge authoring tool, technology database, semantic database, and Web portal service for sharing production technologies for the exterior housing parts of mobile products. By investigating various cellular phone designs, reference form factors for three types of mobile phone housings were designed based on the standard features. In addition, several manufacturing technologies and considerable information such as reference mold designs and molding conditions optimized using CAE and recent R&D outputs are stored in this system.

• Journal of The Korean Society of Grassland and Forage Science
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• v.36 no.1
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• pp.34-40
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• 2016

The objective of this study was to determine the effect of moisture content on the physical and chemical characteristics of Italian ryegrass cube. Cube quality according to moisture contents (15, 20, 25, and 30%) was determined. Cubes made with 15 to 20% moisture showed a little cracks. But, the amount of powder generate from these cubes were lower by 10 to 16% compared to other cubes made with 25 to 30% moisture contents. The highest hardness at 159 kg/f was obtained when the cube was made with 15% moisture content and the lowest was 70 kg/f when the cube was made with 30% moisture content. The electrical loading and surface temperature were increased when moisture content was decreased. The chemical compositions of cube were differ from those of raw materials. Crude protein (CP) and ether extract (EE) contents were increased after cubing works. However, crude fiber (CF), acid detergent fiber (ADF), and neutral detergent fiber (NDF) contents were decreased after cubing. The crude ash content was not significantly (p > 0.05) different between raw material and cube. Higher moisture content resulted in higher crude protein content. However, crude fiber and crude ash content were not significantly (p > 0.05) different between each other. The contents of ADF and NDF were the lowest in cubes made with 30% moisture content. Our results suggest that the proper moisture content of Italian ryegrass cubing is recommended to be 15 to 20% and that cubing works should help increase forage quality.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.1007-1012
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• 2002

Physicochemical and organoleptic properties were investigated in starch extracted from acorn gamma-irradiated for insect control. Hunter's color L, a, and b values were unchanged upon irradiation at 0.25 to 10 kGy. Scanning electron microscopic observation revealed no changes with gamma irradiation at 1 kGy, that is effective for disinifestation, whereas 10 kGy resulted in some clefts on the starch surface. X-ray diffraction analysis showed patterns of both amorphous and crystalline regions were not different among the treatment groups. Water-binding property, swelling power, solubility, and gelatinization patterns of starch were influenced by irradiation dose, but 1 kGy dose was not detrimental to the physicochemical properties. Textural parameters of acorn gel were relatively stable, but significant reductions were found in hardness, adhesiveness, and chewiness in samples irradiated at 3 kGy or higher. Rrsults revealed that irradiation at 1 kGy or lower could be applied for insect control without causing apparent changes in physicochemical and organoleptic properties of acorn starch.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.9
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• pp.1198-1204
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• 2007

This study was carried out to find the optimal conditions for the extraction of the effective ingredients based on central composite by monitoring the extraction characteristics of each ingredient with a response surface methodology. The optimal condition for the effective component alliin was extract temperature of $60.86^{\circ}C$, extract time of 3.77 hr, and ethanol concentration of 50.68%, and that for allicin was $65.11^{\circ}C$, 2.79 hr, and 13.62%, respectively, with the maximum extraction of 16.72 mg%. The maximum value of extracted total phenolics was 16.72 mg%, the optimal condition for electron donating ability was $93.35^{\circ}C$, 3.22 hr and 10.38%. The optimal conditions for pH 1.2 and 3.0 nitrite-scavenging ability was extract temperature of $79.77^{\circ}C$ and $76.46^{\circ}C$, extract time of 3.22 hr and 3.31 hr, and the ethanol concentration of 10.38% and 1.12%, respectively. With this optimal condition, the obtained maximum values for nitrite-scavenging activities at pH 1.2 and 3.0 were 94.85% and 63.22%, respectively.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.119-119
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• 2009

인버터 DC 저항용접의 적용성 증대 : 인버터 DC 저항용접 공법이 SPOT, PROJECTON, SEAM, BUTT 등의 공정에 다양하게 적용되어 저항용접 현장에서 고효율, 친환경적 용접 환경을 만드는데 일조 하고 있다. 특히 자동차의 경량화, 충돌내성 증대, 진동 및 내구성 증대, 공간활용 극대화, 새로운 Design 개념 적용 등의 산업전반에 걸쳐 나타나는 신 Trends로 고 장력 철재의 적용 범위가 확대되고 HSS(High Strength Steel), EHSS(Extra High Strength Steel), UHSS (Ultra High strength Steel ; Hot - Formed Steel )등 다양한 철판의 SPOT 저항용접이 필요하게 되었다. 기존의 AC 단상용접의 전력 특성 상 통전 중 무 통전 시간 과 높은 PEAK 전력, 단상 대 전력 소모로 인한 전력 DROP 등의 문제로 인하여 신소재의 용접 시 매우 많은 Spatter가 발생하고, 높은 용접품질의 확보가 어려워 지므로 이를 대체하기 위한 공법으로 MFDC ( 인버터 DC 저항용접공법 )이 적용되고 있다. 인버터 DC 저항용접의 적응제어 : MFDC라는 높은 효율의 용접 전력원이 확보 됨에도 불구하고 용접현장에서는 원 자재, 도금 등의 품질 산포, 프레스 물의 가공산포, 공기압 산포, 전극 과열 및 마모 등의 요인에 의하여 저항용접 산포가 발생하고 있다. 이는 인위적인 조작이 어렵고 불규칙적이며, 어디서나 산재하고 있는 문제이다. 이를 용접전력 제어 법으로 개선하여 일정한 용접성을 확보하기 위한 노력이 적응제어 기법이다. 정 전류, 정 전력 제어는 정량 제어로 용접 물을 비롯한 용접부의 변화와는 관계없이 설정된 일정량의 전력을 공급하기만 하는데 반하여 적응제어는 적절한 용접 작업 시의 용접 물의 상태, 전극의 가압, 표면 상태 등에 따른 변화 페턴을 기억하고 이후 진행되는 용접에 대하여 정상 페턴과의 차이를 감지 이를 보상하므로 고품질의 용접성을 보장하는 제어기법이다. 따라서 다양한 용접 산포 유발 요인에 의해 용접부의 변화가 발생한다 하여도 그 변화를 감지 하고 적절한 용접전력을 공급한다면 고품질의 용접성을 확보하는데 유용한 공법이 될 수 있다. 인버터 DC 저항용접의 SPC 관리 : SPOT 용접 시 획득할 수 있는 다양한 파라메터에 대하여 모니터링 하고 이 자료를 data 화 하여 품질 관리에 응용하게 되면 양산라인에서 반복적으로 발생되는 문제점을 확인 할 수 있고 이를 통계적 방법으로 추적 개선해 나간다면 용접 불량 감소 및 생산성 향상에 도움이 되며 작업자의 공정 능력 향상 및 기업의 기술축적에도 높은 기여를 할 수 있을 것이다. 용접 적응제어와 다양한 파라메터 모니터링이 한 system에서 이루어 질 때 높은 용접성 확보와 불량률 감소, 원가절감, 생산성 향상 등의 효과가 극대화 될 것이다.

• Korean Journal of Food Science and Technology
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• v.53 no.5
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• pp.634-639
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• 2021

This study investigated the effects of cold plasma (CP) treatment on the properties of biopolymer films prepared with defatted mustard meal (DMM films). CP treatments using N₂, O₂, He, Ar, and dry air did not affect the tensile properties, water vapor permeability, color, and morphology of DMM films, whereas the treatments using He and Ar improved their printability. The tensile strength (TS) of O₂- or air-CP-treated DMM films and the elastic modulus (EM) of O₂-, He-, Ar-, or air-CP-treated films were lower than those of the untreated films. An increase in the power of Ar-CP treatment resulted in an increase in EM. The optimum treatment power and time for minimizing yellowness changes by Ar-CP treatment were 420 W and 40 min, respectively. The results demonstrated the potential application of CP treatment to improve the film properties of DMM films and possibly other agricultural by-product-based biopolymer films, making the films more applicable to food packaging.