The theoretical capacity of silicon-based anode materials is more than 10 times higher than the capacity of graphite, so silicon can be used as an alternative to graphite anode materials. However, silicon has a much higher contraction and expansion rate due to lithiation of the anode material during the charge and discharge processes, compared to graphite anode materials, resulting in the pulverization of silicon particles during repeated charge and discharge. To compensate for the above issues, there is a growing interest in SiOx materials with a silica or carbon coating to minimize the expansion of the silicon. In this study, spherical silica (SiO2) was synthesized using TEOS as a starting material for the fabrication of such SiOx through heating in a reduction atmosphere. SiOx powder was produced by adding PVA as a carbon source and inducing the reduction of silica by the carbothermal reduction method. The ratio of TEOS to distilled water, the stirring time, and the amount of PVA added were adjusted to induce size and morphology, resulting in uniform nanosized spherical silica particles. For the reduction of the spherical monodisperse silica particles, a nitrogen gas atmosphere mixed with 5 % hydrogen was applied, and oxygen atoms in the silica were selectively removed by the carbothermal reduction method. The produced SiOx powder was characterized by FE-SEM to examine the morphology and size changes of the particles, and XPS and FT-IR were used to examine the x value (O/Si ratio) of the synthesized SiOx.

본 논문에서는 구조물의 좌굴 온도와 좌굴 형상을 제어하는 새로운 크기 최적화 방법에 대해서 소개한다. 구조적 안정성 관점에서 구조물의 좌굴 온도와 좌굴 형상을 예측하는 것은 중요한 주제 중 하나이다. 이를 공학적인 직관을 통해 예측하고 최적화된 구조 설계 를 하는 것은 너무나 어려운 과제이다. 이러한 한계점을 해결하기 위해 본 연구에서는 유한요소 시뮬레이션과 치수 최적 설계 방식의 조합을 제안한다. 구조물의 좌굴 온도와 좌굴 형상이 구조물의 두께에 영향을 받는다는 생각에서 착안해 설계 변수를 구조물의 노드 의 두께 값으로 설정했다. 좌굴 온도 값과 좌굴 형상을 목적 함수로 정해진 부피 값을 제약 조건으로 두었다. 치수 최적 설계를 통해 원 하는 좌굴 온도와 좌굴 형상을 유도하기 위한 최적의 두께 분포를 결정할 수 있다. 제안된 치수 최적 설계의 타당성은 본 논문의 다양 한 직사각형 복합 구조물 예제들을 사용해서 검증하였다.

본 연구에서는 DVR 내부 공기유동을 직접 제어하여 CPU의 온도를 낮추기 위한 유동제어 구조물을 제안하였다. 제안된 구조물은 세 개의 얇은 판의 형태로 구성되었으며, DVR 내부의 공기 유동을 포괄적으로 제어하여 CPU의 효율적인 방열을 유도하고자 하였다. DOE와 RSM을 이용한 매개변수 연구기법을 통해 유동제어 구조물의 형상을 최적화하였으며, 해석에는 유한체적방법을 이용한 유체역학 분석 패키지인 FlowVision을 사용하였다. 실제 DVR 기기에서의 실험을 통해 해석 결과를 검증한 결과 CPU의 온도가 16.1℃ 낮아짐을 확인하였다

Gd2O3:Eu3+ red phosphors were prepared by template method from crystalline cellulose impregnated by metal salt. The crystallite size and photoluminescence(PL) property of Gd2O3:Eu3+ red phosphors were controlled by varying the calcination temperature and Eu3+ mol ratio. The nano dispersion of Gd2O3:Eu3+ was also conducted with a bead mill wet process. Dependent on the time of bead milling, Gd2O3:Eu3+ nanosol of around 100 nm (median particle size : D50) was produced. As the bead milling process proceeded, the luminescent efficiency decreased due to the low crystallinity of the Gd2O3:Eu3+ nanoparticles. In spite of the low PL property of Gd2O3:Eu3+ nanosol, it was observed that the photoluminescent property was recovered after re-calcination. In addition, in the dispersed nanosol treated at 85 oC, a self assembly phenomenon between particles appeared, and the particles changed from spherical to rod-shaped. These results indicate that particle growth occurs due to mutual assembly of Gd(OH)3 particles, which is the hydration of Gd2O3 particles, in aqueous solvent at 85 oC.

Anodic aluminum oxide (AAO) has been widely used for the development and fabrication of nano-powder with various morphologies such as particle, wire, rod, and tube. So far, many researchers have reported about shape control and fabrication of AAO films. However, they have reported on the shape control with different diameter and length of anodic aluminum oxide mainly. We present a combined mild-hard (or hard-mild) anodization to prepare shape-controlled AAO films. Two main parameters which are combination mild-hard (or hard-mild) anodization and run-time of voltage control are applied in this work. The voltages of mild and hard anodization are respectively 40 and 80 V. Anodization was conducted on the aluminum sheet in 0.3 mole oxalic acid at 4oC. AAO films with morphologies of varying interpore distance, branch-shaped pore, diameter-modulated pore and long funnel-shaped pore were fabricated. Those shapes will be able to apply to fabricate novel nano-materials with potential application which is especially a support to prevent volume expansion of inserted active materials, such as metal silicon or tin powder, in lithium ion battery. The silicon powder electrode using an AAO as a support shows outstanding cycle performance as 1003 mAh/g up to 200 cycles.

The researches related to active control systems utilizing superelastic shape memory alloys (SMA) have been recently conducted to reduce critical damage due to lateral deformation after severe earthquakes. Although Superelastic SMAs undergo considerable inelastic deformation, they can return to original conditions without heat treatment only after stress removal. We can expect the mitigation of residual deformation owing to inherent recentering characteristics when these smart materials are installed at the part where large deformation is likely to occur. Therefore, the primary purpose of this research is to develop concentrically braced frames (CBFs) with superelastic SMA bracing systems and to evaluate the seismic performance of such frame structures. In order to investigate the inter-story drift response of CBF structures, 3- and 6-story buildings were design according to current design specifications, and then nonlinear time-history analyses were performed on numerical 2D frame models. Based on the numerical analysis results, it can be comparatively verified that the CBFs with superelastic SMA bracing systems have more structural advantages in terms of energy dissipation and recentering behavior than those with conventional steel bracing systems.

has the characteristic is controlling the inhibition or promotion of particle growth by adsorbing onto specific facets of platinum nanoparticles. Therefore, in this study, was added to control the shape of platinum nanoparticles during the liquid phase reduction process. Consequently, platinum cubes were synthesized when of 1.1 mol% (with respect to the Pt concentration) was added into the solution. Platinum octahedrons were synthesized when 32 mol% (with respect to the Pt concentration) was added into the solution. These results demonstrate that the metal salt , effectively controlled the relative growth rates of each facet of Pt nano particles.

This study aimed to find the differences in weight control status and eating behavior of satisfied and dissatisfied female high school students regarding their own body shape. The participants consisted of 238 students at two female high schools in Nonsan-si, Chungnam-do in May of 2008. Self-assessment evaluated present body shape and ideal body shape they would like to have by providing silhouette drawings. The subjects were divided into two groups, 'satisfied' and 'dissatisfied', according to the differences between present body shape and ideal body shape. In the distribution of subjects according to body mass index, 100% of overweight, 97.0% of normal weight and 48.7% of underweight belonged to the dissatisfied group. There were significant differences in weight control and eating behavior between dissatisfied and satisfied groups in terms of frequency and reasons of conducting weight control behavior, body weight return after weight reduction, skipping breakfast and consuming fast food. The satisfied group was two times more likely to not conduct weight control behaviors compared to the dissatisfied group. The main reason for trying to control weight differed according to the group; the reason was feeling fat in the dissatisfied group and desiring to be healthy in the satisfied group. The percentage of subjects that returned to their original weights after weight reduction was 5 times higher in the dissatisfied group. The percentages of subjects that regularly skip breakfast and consume fast food were both higher in the dissatisfied group than in the satisfied group. The dissatisfied group responded 'eating alone' more frequently among nine binge eating behaviors compared to the satisfied group. Both groups, however, did not show any difference in overeating of meals, eating speed, intake frequency of regular meals, food preference, preferred cooking method, carbonated beverage intake and snack eating behavior. In summary, the dissatisfied group tried more unnecessary body weight reduction and had poor eating behavior. Accordingly, to correct the biased perception of body shape by the majority of female high school students, the values of our society should change toward the pursuit of beauty of health.

The study analyzed the body shape perception, weight control attitude, nutrition knowledge, and dietary habits of 529 high school students in Jeju surveyed from January 14-18, 2008 according to students' body shape satisfaction, with the aim of providing basic nutritional education data to aid in appropriate weight control for high school students. The data were analyzed by descriptive analysis, T-test, Chi-square test, ANOVA, and Pearson's correlation coefficients, using the SPSS Win 12.0 program. The body mass index (BMI) of subjects was in the normal range. With regard to weight distribution, 59.4% of subjects showed normal weight and girls were significantly more underweight than boys. More girls considered themselves to be fatter than boys and tended to be increasingly dissatisfied with their body shape. Both boys and girls were more interested in weight control for obesity and were significantly less satisfied with their body shape. Efforts at weight control and reduction had occurred significantly more often for girls than for boys. Dietary attitude scores were significantly higher in girls than boys. BMI positively correlated to weight control concern and nutrition knowledge positively correlated to dietary attitude. BMI negatively correlated to the body shape satisfaction, which in turn negatively correlated to food ingestion disorders. Therefore, it is necessary to develop a systematic nutrition educational program that can induce changes in dietary behavior and increase accurate perception and satisfaction of body shape.

가변단면 압출기술은 사용하는 금형의 조합에 의해 다양한 가공이 가능한 성형공법으로, 압출시에 금형의 움직임에 의하여 제품의 단면형상을 변화시키거나, 치수와 두께를 동시에 변화시킬 수 있다. 압출공정에서 압출속도, 압출압력, 압출온도는 압출품의 표면결함이나 내부품질에 있어 중요한 영향인자이다. 그중 일정한 압출속도는 균일한 메탈 플로를 형성하여 성형품질에 있어서 고른 상태를 유지하게 만드는 요소이다. 기존의 압출 성형에서 펌프토출양의 변화에 의한 추출속도변동 문제는 램 속도의 변화를 계측하고 토출 양을 조정함으로써 압출속도를 제어하는 방법으로 해결한다. 그러나 가변단면 압출공정에서는 제품의 단면형상의 변화에 따라 압출비가 변하므로 이에 따른 램 속도 제어가 있어야만 한다. 본 연구에서는 가변단면 압출공정에서 가공형상에 따른 제어 알고리즘을 제시하여 가변 형상에 따른 램의 이동 속도 및 위치를 제공하려 한다.

This study investigated a mechanism for controlling the shape of Cu nanocrystals fabricated using the polyol process, which considers the thermodynamic transition from a facetted surface to a rough surface and the growth mechanisms of nanocrystals with facetted or rough surfaces. The facetted surfaces were stable at relatively low temperatures due to the low entropy of perfectly facetted surfaces. Nanocrystals fabricated using a coordinative surfactant stabilized the facetted surface at a higher temperature than those fabricated using a non-coordinative surfactant. The growth rate of the surface under a given driving force was dependent on the surface structure, i.e., facetted or rough, and the growth of a facetted surface was a thermally activated process. Surface twins decreased the activation energy for growth of the facetted surface and resulted in rod- or wire-shaped nanocrystals

The W/O emulsion was formed by mixing hydrophobic nonion surfactants of span 80 and tween 60 with kerosine, and by adding sodium silicate aqueous solution. Precipitating the W/O emulsion by sodium bicarbonate resulted in spherical silica particles. Shape and size distribution of silica particles were observed. The particles were spherical and they have narrow size distribution. Particle sizes were 9.29, 7.39 and 5.73 μm at homogenizer speed of 2500, 3000, and 3500 rpm, respectively. The particle size was decreased by increasing agitation speed due to the formation of emulsion droplet. At fixed agitation speed, absorbed paraffin oil weight were measured and the SiO2/Na2O mole ratio effects on particle size were investigated. Particle size was decreased by increasing the mole ratio of SiO2/Na2O.

생물학적 자극통제 수단으로서 활용하기 위한 새로운 돼지 웅성 페르몬성 물질을 탐색하고자 lipocalin의 수용체인 돼지 웅성 페르몬 P1과 P2의 리간드에 기초하여 54개의 P1 및 P2 유사체들에 대한 분자 유사성 지수 (S)는 물론, 분자량 (MWt), 소수성 (logP), 몰라 굴절율 (MR), van der Waals 분자 표면적 (SA), van der Waals 분자 부피 (MV), HOMO, LUMO 에너지, 이온화 포텐셜 (IP), 생성열 (HF), 리폴(lipole), 쌍극자 능율 (DM) 및 전체 에너지 (TE)등, 다양한 13종의 물리-화학 파라미터들을 계산하고 비교 검토하였다. 이들 스테로이드 유사체들의 물리-화학적인 성질은 주로 A와 D-고리가 입체적으로 상이함에 따라 의존적이었며 또한, S와 MV 상수와의 상관관계로부터 분자들의 MV상수가 작아질수록 S=1에 근접하는 경향이었다. 이같은 결과에 근거하여 P1-1과 P2-1 등, 2개의 화합물이 유사성 지수뿐 만 아니라, 소수성, 몰라 굴절율 및 분자부피 등의 측면에서 기존의 페르몬성 물질과 유사한 경향을 보이므로 새로운 돼지 웅성 페로몬성 화합물로 예상되었다.