• The Journal of Korean Association of Computer Education
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• v.14 no.1
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• pp.175-185
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• 2011

Recently RFID systems have been introduced in place of barcode systems to industries such as logistics, distribution, and manufacturing. Due to security vulnerabilities in wireless communication between the reader and tags, however, the authentication protocols for the communication have also been researched extensively. In order to solve the vulnerability of previously proposed protocols, this paper thus proposes an authentication protocol that satisfies the security requirements in the RFID system and minimizes the quantity of computation such as random number generation, transmitting the micro-time of databases. In addition, it is expected that the proposed cross authentication protocol is safe against replay attack, spoofing attack, traffic analysis, and eavesdropping attack when it is applied to the RFID system. Also, it has advantages such as providing a high level of security at a lower manufacturing cost.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.110-110
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• 2017

마이크로 플루이딕 디바이스는 화학, 생물학 실험 및 생체 의학 진단을 위한 플랫폼으로 지난 20년간 그 사용 및 연구가 증가되어 왔다. 마이크로 플루이딕 디바이스를 제작하는 데 있어 가장 일반적으로 사용되는 재료는 실리콘이지만 비용이 많이 들고 불투명하므로 광학 검출이 필요한 곳에 적용이 제한된다. 이러한 측면에서 열가소성 플라스틱은 상업화의 중요한 요소인 대량 생산에 있어 큰 잠재력을 가지고 있으며 저렴하고, 가공이 쉽고, 유연하고, 광학적으로 투명하고, 화학적으로 불활성이며, 생체적합성을 가진다. 본 연구에서는 열가소성 플라스틱의 일종인 PMMA Poly(methylmethacrylate)를 효율적으로 접합하기 위해 비교적 낮은 온도와 낮은 압력에서 에탄올을 활용한 접착방식을 개발하였다. 먼저, PMMA 기판의 전체 표면을 $80^{\circ}C$에서 20 분 동안 에탄올로 처리한 후, $60^{\circ}C$에서 20 분간 열 압착하는 방식으로 영구적인 결합이 이루어졌다. 결합 강도 및 채널의 sealing 정도를 확인하기 위해, 인장 강도, 누수 및 파열 테스트를 수행하였다. 결합강도는 약 12.4 MPa로 타 연구와 비교할 때 매우 높았으며 마이크로 채널의 전체 내부 체적보다 거의 450 배 높은 강한 액체 흐름을 견딜 정도로 견고한 결합이 유지되었다. 열가소성 플라스틱의 본딩에 사용되는 유기 용매는 광학 특성을 희생시키지 않으면서 결합 속도를 높일 수 있지만, 결합 공정 중에 용매로 인해 마이크로 채널이 막히는 현상이 발생될 수 있다. 따라서, 견고한 본딩을 유지하면서 채널 막힘을 방지하기 위해 마이크로 채널을 소수성으로 선택적으로 처리하여 내벽의 표면 특성을 튜닝해 주는 기법을 추가로 적용하였다. 본 연구에서 사용한 방법은 아민-PDMS (polydimethylsiloxane) 링커를 적용하여 기판 표면의 극성을 변경시켜 주었다. 아민-PDMS 링커는 PC (polycarbonate), PET (polyethylene terephthalate), PVC (polyvinyl chloride) 및 PI (polyimide)와 같은 다양한 열가소성 플라스틱의 표면 소수성을 현저히 증가시키며 화학적, 열적 안정성이 뛰어나다. 아민-PDMS 링커는 PMMA의 카보닐 그룹과 반응할 수 있는 아민 사이드 그룹을 포함하는 PDMS 백본으로 구성되며 처리된 대상표면을 소수성으로 만든다. 아민-PDMS 링커 처리 이후 채널은 소수성으로 변화되었으며 이는 접촉각(contact angle)의 증가로 확인되었다. 코팅된 채널을 에탄올로 30분간 80도에서 처리하여도 소수성은 그대로 유지되어 마이크로 채널의 선택적인 소수성 코팅이 성공적으로 수행되었다.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.123-128
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• 2018

Effect of activators in flux on the printability and wettability of a solder paste was evaluated in this study. The activators in this study were dicarboxylic acids, which were oxalic acid (n = 0), malonic acid (n = 1), succinic acid (n = 2), glutaric acid (n = 3), adipic acid (n = 4), and pimelic acid (n = 5). When the solder pastes were observed with a SMT scope, solder with glutaric acid showed clean and shiny surface when it was melted. Slump ratio of the solder pastes was low when the carbon numbers of the dicarboxylic acid were 1-3. Spreadability was high when the carbon number was over 2. Zero cross time of wetting balance test was under 1 sec when the carbon number was over 3. When activator was oxalic acid or malonic acid, zero cross time was over 1 sec and maximum wetting force was low. Fluxes with the oxalic acid and malonic acid showed decomposition at the temperature close to melting point. Among the dicarboxylic acids, glutaric acid provided excellent slump, spreadability, and wettability.

• Korean Journal of Food Science and Technology
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• v.54 no.2
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• pp.203-208
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• 2022

Gluten is an insoluble protein present in cereals such as wheat. Gluten consumed through food is not digested and accumulates in the body; this has been linked to digestive discomfort, irritation, and various digestive disorders, including intestinal inflammation. In this study, the Lactobacillus paracasei strain GLU70, which exhibits a glutendegrading ability, was isolated from salted seafood. At a pH of 3.0, GLU70 showed a survival rate of approximately 84%, and at 0.3% oxgall, it showed a survival rate of approximately 53%. When the culture supernatant collected after 12 h of incubation was added to flour dough, approximately 50% gluten degradation was observed. Moreover, among several probiotic isolates exhibiting proteolytic activity selected to assess the gluten-degrading ability, GLU70 showed superior results regardless of the dough fermentation temperature. Although further research is required, GLU70 is expected to be of value in manufacturing gluten-reduced products and the food industry as an ingredient or additive.

• Food Science and Preservation
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• v.12 no.1
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• pp.62-67
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• 2005

Microwave-assisted extraction (50 W, 2,450 MHz, MAE) with properties of selective heating and subsequent extraction for certain phytochemicals from natural materials was applied to pre-establish the extraction conditions for total yield total phenolics, and electron donating ability (EDA) from Brossica oleacea. The experiments with $50\%$ EtOH solvent showed that 20 mesh in particle size of cabbage flake $(moisture\;4.5\%)$ and 1:10 (g/mL) in the sample to solvent ratio for both raw $(moisture\;90.2\%)$ and flake cabbages were optimal for MAE efficiency. Under these conditions, total yield increased with extraction tim, which was highest for raw cabbage extract in $50\%\;EtOH$ solvent followed by $100\%\;EtOH$ and water. While that of flake cabbage extracts was highest in $50\%\;EtOH$ followed by water and $100\%\;EtOH$. The contents of total phenolics and EDA in extracts gradually increased after 3 min of MAE, which were highest when using $100\%\;EtOH$ solvent followed by $50\%\;EtOH$ and water in raw cabbage and $50\%\;EtOH$ followed by water and $100\%\;EtOH$ in flake cabbage, respectively.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.63-72
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• 2012

Current analysis method drives an irrationality a road, signal operation and cause confusion of road such as weaving, bottleneck being not including main traffic flow in analysis subject. Therefore, this research develops analysis method of simple grade facilities to grasp target equipment relationship effect as virtue process to grasp effect of simple grade facilities in city and there is the purpose to apply optimum space of analysis intersection. In this paper, get at effect of simple grade facilities in urban area, as well as, develop new analysis method of simple grade facilities and adapt optimal interval of intersection point. New method of this paper reasonably estimated to optimal interval of the traffic flow(diverge area, merge area). As research result, analysis method to present in this research could clarify vague part of existing analysis method and presume reasonable result. Optimal interval of diverge and merge area with facilities was appeared more then 65m from the main line and more then 45m from the frontage road. Meaning of this paper as follow. First, the effect of simple grade facilities estimate. as consider optimal interval of simple grade facilities in urban can plan efficiently operation planning of road and signal in connection with nearby intersection. Second, new method then previous methods. planner of transportation easily access due to run parallel with existing method. Third, new method is contained through traffic volumes. the existing method did not reflect one. and this new method reduce error to the minimum. when analysis of intersection and link. Fourth, using the new method propose improvement plan with road operation and signal operation.