• 한국재료학회지
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• 제20권8호
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• pp.418-422
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• 2010

As a starting material, BCP (biphasic calcium phosphate) nano powder was synthesized by a hydrothermal microwave-assisted process. A highly porous BCP scaffold was fabricated by the sponge replica method using 60 ppi (pore per inch) of polyurethane sponge. The BCP scaffold had interconnected pores ranging from $100\;{\mu}m$ to $1000\;{\mu}m$, which were similar to natural cancellous bone. To realize the antibacterial property, a microwave-assisted nano Ag spot coating process was used. The morphology and distribution of nano Ag particles were different depending on the coating conditions, such as concentration of the $AgNO_3$ solution, microwave irradiation times, etc. With an increased microwave irradiation time, the amount of coated nano Ag particles increased. The surface of the BCP scaffold was totally covered with nano Ag particles homogeneously at 20 seconds of microwave irradiation time when 0.6 g of $AgNO_3$ was used. With an increased amount of $AgNO_3$ and irradiation time, the size of the coated particles increased. Antibacterial activities of the solution extracted from the Ag-coated BCP scaffold were examined against gram-negative (Escherichia coli) and gram-positive bacteria (Staphylococcus aureus). When 0.6 g of $AgNO_3$ was used for coating the Ag-coated scaffold, it showed higher antibacterial activities than that of the Ag-coated scaffold using 0.8 g of $AgNO_3$.

• 한국식품과학회지
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• 제1권1호
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• pp.78-84
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• 1969

An attempt has been made to investigate the possible occurrence of aflatoxins, a group of micotoxin which are toxic metabolites produced by Aspergillus flavus, and aflatoxin like substances in fungal fermented soybean products such as meju and soybean paste. Chloroform extracts from 15 samples which has been defated with petroleum ether are subjected to separations with thin-layer chromatography on silica gel washed with methanol prior to film coating, improves the chromatographic separation and ultraviolet absorption spectral identification. In addition to fluorescencing spot having an Rf value which is same as aflatoxin $B_1$, many of the fluorescencing spots have been occurred in every sample examined. Each fluorescencing spot is scratched and the ethanol extracts are subjected to further separation with thin-layer chromatography. Each fluorescence substance is eluted with ultra violet transparent absolute ethanol and the ultraviolet absorption spectra are checked. None of the absorption curve of eluates shsow accordance with the curve of aflatoxin. 2, 4-Dinitrophenyl hydrazine reagent, Tollen's reagent and ninhydrin reagent are applied on the chromatogram- The data show that aflatoxin is not present in any of the fungal preparations examined.

• 한국작물학회지
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• 제36권4호
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• pp.324-331
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• 1991

벼 침수직파재배법 확립을 위해 파종량과 산소 발생제 처리를 달리하여 침수토중직파재배 싱험을 실시한 결과를 요약하면 다음과 같다. 1 침수토중직파에서 CaO$_2$ 분의처리나 CaO$_2$와 규조토의 혼합 의처리는 입모율은 크게 향상 시켰으나 $m^2$당 개체수가 증가함에 따라 도복발생 정도가 심해져 수량증대에는 크게 기여하지 못했다 2. 침수토중직파에서 적정파종량과 1주 파종입수는 CaO$_2$ 분의처리에서는 3.3Kg종자/10a와 1주 3입파였고 산소발생제 무처리의 경우 5.6Kg 종자/10a와 1주 5입파였다. 3. 경로 계수 맥석의 결과에 의하면 수량에 대하여 등숙률의 직접 효과가 가장 커 도복 억제를 통한 등숙률의 향상이 침수 토중 직파 재배의 수량 증대에 가장 중요한 것으로 생각된다.

• 한국산학기술학회논문지
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• 제19권10호
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• pp.339-345
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• 2018

본 논문은 기존의 단일 파장의 UV(Ultraviolet: 자외선)-LED(Light-Emitting Diode) 경화형 코팅 방법과 달리 UV 파장에서 동작되는 LED를 중첩한 다중 집광성 UV-LED 경화형 코팅의 경화 특성에 대해 연구하였다. 각각 365nm, 395nm, 420nm, 450nm 단일 파장의 UV-LED 광원을 선정하여 광원의 광속, 지향각 등 광 특성을 분석하였으며, 또한 UV-LED 광원의 파장별 경화 특성에 대해 분석을 통하여 복합 파장에 대한 LED를 최적화를 진행하였다. 다파장 UV 광원이 중첩되었을 경우 경화 성능 상태를 전산모의 실험을 통해 예측하였으며 실제 설계 및 제작을 하였다. 내부 고속경화도 향상을 위해 각각의 LED를 집광시켜 동일한 위치에서 다파장이 합성, 집광되는 multi-spot 방식 모듈을 제작하여 파장 조합 조건을 달리하여 경화제의 접착력 및 표면, 내부 경화도를 실험하였다. 경도계와 FT-IR 분석 장비를 이용하여 표면 경화와 내부 경화 상태를 비교 분석하였다. 그 결과, 단일 파장보다 UV-LED 4파장을 중첩한 multi-spot방식이 표면 및 내부 경화도의 특성이 높아짐을 확인할 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.430-433
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• 2005

Laser bonding between similar and dissimilar thermoplastics has been investigated by making use of laser transmission weld technique. Spot welding of two layers of plastic materials has been demonstrated by using of a high-quality diode-laser with 808nm wavelength. Weld areas increases according to power density, exposure time. The results of peel out test show that peel strengths increase with the area of molten plastics. Layers, which have the same chemical properties, have good bonding qualities. A bonding method which dye film is coated on the interface is used for laser bonding between plastics with high transmission for laser wavelength. Laser transmission bonding is worthy of attention because it is not in contact, requires a few tooling devices, allows a flexible energy delivery and produces nearly invisible welds

• 한국레이저가공학회지
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• 제2권2호
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• pp.8-17
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• 1999

This study includes a basic feature of laser surface alloying for enhancing the surface properties of materials. Effects of laser processing parameters such as beam power, beam size, scanning speed on the shape and composition of alloyed layer was simulated in case of moving beam conditions (2-dimensional numerical methods). Simulated results were compared with experiments, in which the plasma coating of 80% Ni ＋ 20% Cr deposited on the SS41 substrate was remelted with CO2 laser with Gaussian energy distribution. Simulation and experiments revealed that the shape (dimension)and composition of laser alloyed layer were strongly dependent upon the process parameters, especially interaction time (travel speed) as compared to beam diameter, beam power and absorptivity. The shape and composition of alloyed layervaried more or less exponentially with parameters.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
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• pp.43-46
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• 2006

In this study on the appliable Asphalt sheet of monolithic and inorganic matter waterproofing material using of field because of problem of complex waterproofing sheet. Before this cement polymer modified waterproof coating and appliable asphalt sheet of monolithic whether have stability by method of construction about all style waterproofing that evaluate to new method of construction development naturally big emphasis put and try to approach. Did performance test item first at, as a result, drew by suitable thing in all KS items. This is considered to have more effective spot construction work because if means that have stability by material as well as method of construction.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
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• pp.31-34
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• 2006

In this study on the appliable Asphalt sheet of monolithic and inorganic matter waterproofing material using of field because of problem of complex waterproofing sheet. Before this cement polymer modified waterproof coating and appliable asphalt sheet of monolithic whether have stability by method of construction about all style waterproofing that evaluate to new method of construction development naturally big emphasis put and try to approach. Did performance test item first at, as a result, drew by suitable thing in all KS items. This is considered to have more effective spot construction work because if means that have stability by material as well as method of construction.

• Corrosion Science and Technology
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• 제10권2호
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• pp.47-51
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• 2011

Main issues in the automotive industry are the reduction of vehicle body weight for energy savings and improvement of crashworthiness for passenger safety. In order to address both these issues, there has recently been increasing application of galvannealed advance high strength steel (GA AHSS) sheets for automobiles. However, GA AHSS sheets have some surface defects such as coating bare spots due to the addition of solid-solution strengthening elements, which result in the deterioration of the galvannealing reaction. In this study, the effects of galvannealed manufacturing conditions on surface and mechanical properties, resistance spot weldability on a laboratory scale, and GA 980 MPa steel sheets produced by commercial continuous galvannealing line (CGL) were investigated.

• Corrosion Science and Technology
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• 제9권1호
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• pp.16-19
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• 2010

Application of ultra-high strength steel sheets is one of the most important methods to satisfy weight reduction and crash safety of a vehicle. Recently, there has been a trend to apply ultra-high strength steel sheets widely to underbody parts in which corrosion resistance is required. In this work, ultra-high strength galvannealed steel sheets with a tensile strength of 1180 MPa were developed. Newly developed ultra-high strength galvannealed steel sheets have comparable properties, such as mechanical properties, spot weldability, crashworthiness and adhesion of coatings, to conventional steel sheets.