• 한국응용과학기술학회지
• /
• 제21권4호
• /
• pp.300-305
• /
• 2004

High-solid coatings were prepared by blending of previosly synthesized acrylic resins and hexamethylene diisocyanate-trimer and curing it at room temperature. The characterization of the films of the prepared coatings was performed. The impact resistance, cross-hatch adhesion, $60^{\circ}$specular gloss, and heat resistance of the films proved to be good, and the pencil hardness and drying time proved to be slightly poor. Especially, there was a remarkable improvement in the heat resistance. This improvement may stem from the regular arrangement of ethyl groups introduced into the acrylic resin. As a result of Rigid-body pendulum visco-elasticity measurement, dynamic $T_g$ values of cured films increased with dynamic $T_g$ values.

• Elastomers and Composites
• /
• 제46권3호
• /
• pp.211-217
• /
• 2011

Wood Polymer Composite(WPC)는 우수한 물성 및 가공성과 더불어 자원재활용 및 벌목규제 대응 등의 환경적인 측면에서 각광을 받고 있는 재료이다. 본 연구에서는 이축스크류식 치합형 압출기를 이용하여 상용화 WPC를 제조하였다. WPC의 물성에 영향을 미치는 세 가지 주요 실험 변수 즉 목분의 함량, coupling agent의 함량 그리고 목분의 전처리 영향을 자세히 관찰하였다. 목분의 함량에 따른 WPC의 물성변화는 목분함량이 증가함에 따라 인장강도 와 열안정성이 감소하고, 수분흡수성이 증가하는 것이 관찰되었다. PP-g-MA 첨가 시 기계적 물성은 향상되고, 수분흡수성이 감소하는 것이 관찰되었다. 목분을 전처리하여 제조한 시편에서는 가장 높은 인장강도의 향상을 나타냈지만, 셀룰로스의 결정구조 변화로 수분흡수성이 증가하는 것이 확인되었다.

• 한국산업보건학회지
• /
• 제22권2호
• /
• pp.156-163
• /
• 2012

Objectives: The aim of the present study was undertaken to investigate the association between communication for chemical hazard information and characteristics of occupational safety and health managers. Subjects and Methods: We surveyed 78 occupational safety and health managers(64 male and 14 female) in 78 chemical manufacturing plants. Data were obtained using a self-reported questionnaire about size and type of company, products, communication system for chemicals and work-related characteristics of occupational safety and health managers. All analyses in this study were performed using SPSS program 12.0. Results: 64.1% of the study participants were occupational health managers aged 39.3 years on average and were graduated from college and university around 90%. 30.0% and of them were majoring in chemistry (engineering chemistry), 18.0% occupational health, 16% nursing and 30.0% others. Occupational safety managers were aged 39.4 years on average, 42.9% of them were majoring in chemistry (engineering chemistry), 21.4% environmental engineering, 10.7% occupational safety and 25% others. 86% of occupational health managers and 71.4% of occupational safety managers were classified as office job. Over 94% of the hazards information for chemicals were delivered by occupational safety and health managers, but about 28.2% workers preferred outside experts who have a profound knowledge about occupational safety and health and understandable. Occupational safety and health managers and workers had difficulties in understanding toxicological information, hazards identification, stability/reactivity, composition/information on ingredients, physical/chemical properties and ecological information. On multiple logistic regression analysis for the 16 heading of material safety data sheet, content of material safety data sheet was significantly associated with education level (odds ratio=0.286, 95% confidence interval=0.105-0.780). The hazard identification (odds ratio=3.947, 95% confidence interval=1.092-14.271) and toxicological information (odds ratio=0.841, 95% confidence interval=0.705-0.998) were significantly associated with type of occupation. Conclusions: This finding implies that the education level, type of occupation and speciality of occupational safety and health managers may affects hazards information delivery.

• Journal of Mechanical Science and Technology
• /
• 제15권8호
• /
• pp.1181-1187
• /
• 2001

The radiation driven response function (R$\_$q/) for AP and HMX propellant was obtained and compared with experimental results by using a simple $\alpha$$\beta$γ flame model rather than with detailed chemistry. For an AP propellant, the profile of heat release was assumed by the experimental data. The calculated R$\_$q/ shows a frequency shift of the peak amplitude to the higher frequency and a decrease in the maximum amplitude as radiation increases. In addition, it was found the increase in the total flux could enhance the mean burning rate γ$\_$b/ while the phase differences between the radiation and resulting conduction could consequently reduce the fluctuating amplitude Δγ$\_$b/. Fortunately, this is the qualitative duplication of the behavior recently observed in the experiments of RDX propellants. For HMX, the response function R$\_$q/ has been calculated and showed a quite good agreement with the experimental data. Even though the fairly good agreement of R$\_$q/ with experimental ones, the unsteady behavior of HMX was not reproduced as the radiation input increased. This is due to lack of the material properties of HMX or the physical understanding of HMX burning at high pressure.

• Asian-Australasian Journal of Animal Sciences
• /
• 제27권6호
• /
• pp.886-897
• /
• 2014

The aim of the present study was to get a total physical and chemical characterization and comparison of the principal components in Bangladeshi buffalo (B), Holstein cross (HX), Indigenous cattle (IC) and Red Chittagong Cattle (RCC) milk. Protein and casein (CN) composition and type, casein micellar size (CMS), naturally occurring peptides, free amino acids, fat, milk fat globule size (MFGS), fatty acid composition, carbohydrates, total and individual minerals were analyzed. These components are related to technological and nutritional properties of milk. Consequently, they are important for the dairy industry and in the animal feeding and breeding strategies. Considerable variation in most of the principal components of milk were observed among the animals. The milk of RCC and IC contained higher protein, CN, ${\beta}$-CN, whey protein, lactose, total mineral and P. They were more or less similar in most of the all other components. The B milk was found higher in CN number, in the content of ${\alpha}_{s2}-$, ${\kappa}$-CN and ${\beta}$-lactalbumin, free amino acids, unsaturated fatty acids, Ca and Ca:P. The B milk was also lower in ${\beta}$-lactoglobulin content and had the largest CMS and MFGS. Proportion of CN to whey protein was lower in HX milk and this milk was found higher in ${\beta}$-lactoglobulin and naturally occuring peptides. Considering the results obtained including the ratio of ${\alpha}_{s1}-$, ${\alpha}_{s2}-$, ${\beta}$- and ${\kappa}$-CN, B and RCC milk showed best data both from nutritional and technological aspects.

• 공업화학
• /
• 제35권4호
• /
• pp.267-272
• /
• 2024

본 논문에서는 미세유체장치 기반 외부 자극에 의한 결정화 기술의 최근 발전에 대해 탐구한다. 초음파, 레이저, 마이크로파, 전기장과 같은 대표적인 네 가지 결정화 기법인 외부 자극의 종류에 대해 중점을 두어 외부 자극이 결정 성장에 미치는 영향을 강조한다. 결정 품질 향상, 구조 형성, 물리적 특성 변화 등의 이점을 강조하며 외부 자극을 통한 결정화(external-source-induced crystallization) 기술에 대한 포괄적인 개요를 제공하고 잠재적인 발전 가능성에 대해 논의한다.

• 보존과학회지
• /
• 제33권2호
• /
• pp.131-147
• /
• 2017

본 연구는 김제 동곡마을 도요지에서 출토된 15~17세기 분청사기와 백자에 대하여 색도와 비중 및 흡수율, 미세구조 관찰 등의 물리적 특성, 태토와 유약의 조성에 대한 화학적 특성에 대하여 분석하였다. 물리적 특성에서 가마운영 상황과 제작 시기에 따라 제작기술이 점차 발전되는 변화가 관찰된다. 원료적 측면에서 동곡마을 도요지는 동일기반암에서 생성된 점토를 사용하여 도자기 종류, 생산 가마, 시기 등에 따라 원료를 정제하거나 융제를 첨가하는 등의 제작기법에서 차이를 보인다. 백자는 분청사기와 비교하여 착색제 함량이 평균적으로 1.3% 이상 적고 융제 성분 $K_2O$ 함량이 1.2% 가량 많은 편으로 같은 온도에서 더 쉽게 자화될 수 있는 특징을 보인다. 이와 같은 특성은 생산 시기가 늦어질수록 분명하게 나타난다. 유약은 자기 종류가 아닌 생산 시기에 따라 16세기 이후에는 MgO, $TiO_2$, MnO, $P_2O_5$ 등의 함량이 적게는 3배, 많게는 10배 이상 줄어들어 사용 원료에 차이가 있었던 것으로 추정해 볼 수 있다.

• 대한화장품학회지
• /
• 제37권1호
• /
• pp.55-60
• /
• 2011

본 연구에서는 DOPC 리포좀의 안정성에 대한 염의 영향을 알아보기 위하여 증류수, phosphate buffer, 그리고 phosphate bufferd saline으로 리포좀을 제조하였다. 그리고 염의 추가에 따른 리포좀의 입자크기 및 제타전위 등 기본적인 물성 변화를 확인하였다. 그에 앞서 희석에 대한 영향을 알아보고자 리포좀을 각각 제조시 용매로 40배와 80배로 희석하였고 그 결과 같은 용매로 희석시킬 경우 40배 희석까지는 안정한 것을 확인하였다. 증류수로 제조한 리포좀을 증류수, phosphate buffer, 그리고 phosphate buffered saline으로 희석하였고, phosphate buffer로 제조한 리포좀은 phosphate buffer, 그리고 phosphate buffered saline으로 희석하여 염 농도 증가에 따른 리포좀의 입자크기 및 제타전위 변화를 확인하였다. 그 결과 리포좀 분산액 내에 존재하는 염의 양이 증가할수록 리포좀의 입자크기가 약간씩 작아지는 경향을 나타내었고, 제타전위 또한 염의 양이 증가할수록 0에 가까워지는 경향을 나타내었다. 결론적으로, 리포좀의 입자크기와 제타전위는 리포좀의 안정성을 판단할 수 있는 좋은 요소이며 또한 리포좀 제조시의 용매와 다른 조건의 염농도는 리포좀 입자의 안정성에 큰 영향을 줄 수 있다고 사료된다.

• ETRI Journal
• /
• 제32권6호
• /
• pp.881-890
• /
• 2010

Conventional fire detection systems use physical sensors to detect fire. Chemical properties of particles in the air are acquired by sensors and are used by conventional fire detection systems to raise an alarm. However, this can also cause false alarms; for example, a person smoking in a room may trigger a typical fire alarm system. In order to manage false alarms of conventional fire detection systems, a computer vision-based fire detection algorithm is proposed in this paper. The proposed fire detection algorithm consists of two main parts: fire color modeling and motion detection. The algorithm can be used in parallel with conventional fire detection systems to reduce false alarms. It can also be deployed as a stand-alone system to detect fire by using video frames acquired through a video acquisition device. A novel fire color model is developed in CIE $L^*a^*b^*$ color space to identify fire pixels. The proposed fire color model is tested with ten diverse video sequences including different types of fire. The experimental results are quite encouraging in terms of correctly classifying fire pixels according to color information only. The overall fire detection system's performance is tested over a benchmark fire video database, and its performance is compared with the state-of-the-art fire detection method.

• 한국산학기술학회논문지
• /
• 제13권1호
• /
• pp.456-461
• /
• 2012

본 연구에서는 글리세롤과 우레아를 이용하여 글리세롤카보네이트를 합성하는 반응을 진행하였다. ZnO와 Zn-Al 이원계 금속 산화물 촉매를 제조하고, 제조되어진 촉매를 사용하여 글리세롤의 전환율과 글리세롤카보네이트의 수율을 확인하였고, Al의 첨가에 따른 촉매 특성의 분석과 글리세롤카보네이트 합성반응에서의 역할에 대해 확인하였다. 글리세롤카보네이트 합성 반응에서 ZnO를 단독으로 촉매를 사용한 경우보다 Zn-Al 혼합 산화물을 촉매로 사용하여 반응하였을 때, 부반응이 억제되어 전환율 및 수율이 증가함을 확인하였다.