Coatings composited with alumina and Perfluoro alkoxyalkane (PFA) resin were deposited on stainless steel plate (SUS304) to further improve corrosion resistance. Plate (ca. 10μm) and/or nanosize (27~43 nm) alumina used as inorganic additives were mixed in PFA resin to make alumina-fluoro composite coatings. These coatings were deposited on SUS304 plate with wet spray coating and then the film was cured thermally. According to the amount and ratio of the two kinds of alumina having plate morphology and nano size, corrosion resistance of the film was evaluated under strong acids (HF, HCl) and a strong base (NaOH). The film prepared with the addition of 5~10 wt% alumina powders in PFA resin showed corrosion resistance superior to that of pure PFA resin film. However, for the film prepared with alumina content above 10 wt%, the corrosion resistance did not improve with the physical properties, such as surface hardness and adhesion. The film prepared with plate/nanosize (weight ratio = 1/2) alumina especially enhanced the surface hardness and corrosion resistance. This can be explained as showing that the plate and the nanosize alumina dispersed in PFA resin effectively suppressed the penetration of cations and anions due to the long penetration length and fewer defects that accompany the improved surface hardness under a serious environment of 10% HF solution for over 120 hrs.

In order to prevent the high velocity bullet from penetration, aluminum alloy and RHA(Rolled Homogeneous Armour) steel, which have a high tensile and compressive strength, are usually used as the bullet-proof armor material. Although these materials have a good bullet proof performance, but not an area density which is a weight increasing factor of bullet-proof armor. Therefore, Mg(magnesium) alloy is a promising substitute for the traditional bullet-proof armor material due to the relatively low areal density. The spatial efficiency of Mg alloy, however, is inferior to the traditional material's, which is a volume(thickness) increasing factor of bullet-proof armor. In this study, we select the multi-layered hybrid armor which consist of Ceramic, with a high strength; Mg alloy, with a low areal density; Kevlar, with a high tensile strength-to-weight ratio; in order to make up for the poor spatial efficiency of Mg alloy. By predicting V50 of the multi-layered armor against 9mm FMJ(Full Metal Jarket). we show that the multi-layered armor have the capability in improving bullet-proof performance in the respect of the areal density, but also the spatial efficiency.

Recovery of copper powder from copper chloride solution used in leaching process was carried out using a cementation method. Cementation is a simple and economical process, necessitating less energy compared with other recovery methods. Cementation utilizes significant difference in standard reduction potential between copper and iron under standard condition. In the present research, Cementation process variables of temperature, time, and added amount of iron scraps were optimized by using design of experiment method and individual effects on yield and efficiency of copper powder recovery were investigated using bench-scale cementation reaction system. Copper powders thus obtained from cementation process were further characterized using various analytical tools such as XRF, SEM-EDS and laser diffraction and scattering methods. Cementation process necessitated further purification of recovered copper powders and centrifugal separation method was employed, which successfully yielded copper powders of more than 99.65% purity and average in size.

현재 국내에서 EM-120에 의해 검측된 틀림 데이터는 매우 불규칙적인 형태를 나타내며 데이터 분석 시 다양한 문제점 을 가지고 있다. 본 연구에서는 궤도의 효율적인 유지관리를 위해 검측된 틀림데이터의 특징과 문제점을 분석하고, 이를 보완할 수 있는 효율적인 처리 기법을 개발하였으며, 정제된 데이터의 ARIMA 분석을 통해 검측데이터와 계절 변화의 상 관관계 분석을 수행하였다. 또한 회귀모형, 지수평활법, ARIMA 모형 등 다양한 예측 모델의 적용을 통해 검측 데이터의 시계열 분석을 수행하고, 궤도 틀림 데이터의 예측 모델에 적합한 최적 모델 선정과 관련한 연구를 수행하였다.

In this study, we determined total polyphenol content(TPC) and total flavonoid content(TFC) of extracts from Korean cabbage and cabbage using a spectrophotometric method as well as glucosinolates concentration by HPLC. TPCs of Korean cabbage and cabbage extracts were 308.48 ㎍ GAE/g dry weight and 344.75 ㎍ GAE/g dry weight, respectively. TFCs of Korean cabbage and cabbage extracts were 5.33 ㎍ QE/g dry weight and 5.95 ㎍ QE/g dry weight, respectively. We found six different glucosinolates, namely progoitrin, glucoalyssin, gluconapin, glucobrassicanapin, glucobrassicin and 4- methoxyglucobrassicin in the Korean cabbage extract. In the cabbage extract, there was four glucosinolates, namely glucoraphanin, sinigrin, glucobrassicin and 4-methoxyglucobrassicin. We determined the cytotoxic effect of Korean cabbage and cabbage extracts in AGS human stomach cancer cells, HepG2 human hepatic cancer cells and LNCaP human prostate cancer cells by MTT assay. Dose-dependent relationships were found between the extract concentrations and cancer cell growth inhibition. The overall results support that both Korean cabbage and cabbage, the major vegetables in Korea, contain bioactive compounds such as polypheol, flavonoids as well as glucosinolates and they may play a positive role in cancer prevention.

본 연구에서는 유한한 깊이의 투수층에 의한 에너지 감쇠효과를 고려한 파랑의 변형을 해석하였다. 파의 에너지 감쇠율과 상대수심의 관계식을 제시하였으며, 에너지 감쇠율을 고유함수전개법에 사용하여 투수층에 의한 에너지 감쇠를 계산하였다. 투수성이 있는 수중둔덕에 대해서, 수치실험 결과는 해석해로 간주할 수 있는 적분방정식의 결과와 비교하여 잘 일치하였다. 또한, 투수경사에 의한 반사율을 다양한 주파수에 대해서 실험하였으며, 수치실험 결과, 수심이 매우 커서 수면파가 투수층의 영향을 받을 정도가 아닌 경우에는 상대적으로 파장이 짧은 파랑일수록 투수층의 영향을 크게 받는 것으로 나타났다.

기업에서의 설비 대체에 관한 의사결정의 사례로서 구형설비를 신형설비로 대체함으로써 비용절감이 있음을 분석한다.

Magnetic nanoparticles for ferromagnetic fluids and magnetorheological fluids were prepared by chemical coprecipitation and mechanical milling, respectively. The surface-treated particles were dispersed at various weight ratios into a medium of polyethylene glycol. In order to evaluate the elastic modulus of the fluids, ultrasonic pulse velocities were measured with an ultrasonic test using transducers of 5MHz and 2.25MHz. The ultrasonic signals were only available with a transducer of 2.25 MHz at fluid concentrations of 5 mg/ml and lower. In the case of applying transducers over 2.25 MHz and concentrations over 5 mg/ml to the fluids, it was impossible to observe effective ultrasonic signals due to an excessive scattering of the pulses by the dispersed particles. Elastic moduli of the magnetorheological fluids were 5.44 GPa and 6.13 GPa with concentrations of 25 mg/ml and 50 mg/ml, respectively; these values were higher by 40% than the values of 4.04 GPa and 4.28 GPa of ferromagnetic fluids at the same concentrations. As for the effect of an external magnetic field on these dilute fluids, the ultrasonic signals were positioned in a very similar way, which was probably due to insufficient arrangement of the particles even though the reflection energy of the ultrasonic waves apparently increased.

Spherical nanosized cobalt powder with an average size of 150-400 nm was successfully prepared at room temperature from cobalt sulfate heptahydrate (). Wet chemical reduction method was adopted to synthesize nano cobalt powder and hypophosphorous acid () was used as reduction agent. Both the HCP and the FCC Co phase were developed while concentration ranged from 0.7 M to 1.1 M. Secondary phase such as and were also observed. Peaks for the crystalline Co phase having HCP and FCC structure crystallized as increasing the concentration of , indicating that the amount of reduction agent was enough to reduce . Consequently, a homogeneous Co phase could be developed without second phase when the ratio exceeded 7.

현재 야외답사는 개발된 야외 학습장의 부족과 접근의 어려움, 학급 당 학생 수의 과밀화, 거리와 시간의 문제, 그리고 비용의 문제 등으로 극히 제한된 범위에서만 행해지고 있다. 이러한 이유로 실제야외답사의 이점을 장점으로 살리면서 현실적인 어려움을 보완하기 위한 대안이 요구되고 있다. 본 연구의 목적은 플래시 파노라마를 활용하여 웹-기반의 가상야외지질답사를 개발하고 이를 다양하게 활용하기 위한 방안을 탐색하는 것이다. 개발된 제주도 VFT의 특징은 다음과 같다: 중 고등학생들에게 화산 지형과 지질에 관한 학습을 위한 가상의 공간을 제공한다; 웹-기반으로 개발되어 학습 내용에 비순차적으로 접근할 수 있으며, 학생들이 자신의 능력에 따라 학습 속도를 조절할 수 있다; 시공간적 제약과 경제적인 부담이 없고, 같은 장소를 얼마든지 반복적으로 탐구 할 수 있다; 학교급에 따라 수준별로 학습할 수 있는 활동지가 제공된다; 지형 지물의 근접 촬영 이미지, 탐구활동과 관련된 질문과 설명, 해당지역의 실제 암석의 표본 사진 및 박편 이미지 등의 다양한 보충적인 웹 콘텐츠들을 제공한다. 개발된 제주도 VFT를 과학 수업 및 비교과 영역에서 활용할 수 있는 방안과 지도 모형을 각각 제안하였다.

An entomopathogenic bacterium, Photorhabdus temperata ssp. temperata (Ptt), suppresses insect immune responses and facilitates its symbiotic nematode development in target insects. The immunosuppressive activity of Ptt enhances pathogenicity of various microbial pesticides including Bacillus thuringiensis (Bt). This study was performed to select a cheap and efficient bacterial culture medium for large scale culturing of the bacteria. Relatively cheap industrial bacterial culture media (MY and M2) were compared to two research media, Luria-Bertani (LB) and tryptic soy broth (TSB). In all tested media, a constant initial population of Ptt multiplied and reached a stationary phase at 48 h. However, more bacterial colony densities were detected in LB and TSB at the stationary phase compared to two industrial media. All bacterial culture broth gave significant synergism to Bt pathogenicity against third instars of the diamondback moth, Plutella xylostella. Production of bacterial metabolites extracted by either hexane or ethyl acetate did not show any significant difference in total mass among four culture media. Reverse phase HPLC separated the four bacterial metabolites, which were not much different in quantities among four bacterial culture broths. This study suggests that two industrial bacterial culture media can be used to economically culture Ptt in a large scale.