• 한국재료학회지
• /
• 제11권2호
• /
• pp.137-145
• /
• 2001

수용액 매체에서 젤케스팅을 이용하여 복잡한 형상의 세라믹스를 제조하기 위한 새로운 공정을 연구하였다 용융실리카 분말과 첨가제로서 지르콘과 코디어라이트 조성으로 혼합된 현탁액을 electrosteric 방법으로 안정화시켰다. 슬립은 다성분계 세라믹 현탁액에 단량체, 이량체 그러고 분산제를 혼합하고, 볼밀하여 준비하였다. 슬립의 유동학적 특성을 평가하기 위해 점도를 측정하였으며 , 낮은 점도를 갖는 50vo1%의 고농도 다성분계 세라믹 슬립의 제조가 가능하였다. 슬립의 점도는 고분자 분산제의 함량과 단량체 및 이량체의 혼합비에 크게 의존하였다. 성형체는 안정화시킨 슬립을 몰드에 부어 상온에서 젤화시킨 후 $25^{\circ}C$, 80~85% 상대습도 분위기 하에서 48시간동안 건조시켜 제조하였으며 건조된 성형체에는 균열이 발생하지 않았다.

• 한국식생활문화학회지
• /
• 제10권4호
• /
• pp.327-337
• /
• 1995

The purposes of this study were to: (a) identify college students' patronage behaviors, (b) develop an instrument measuring the attitudes of University Students towards university foodservices management practices, (c) determine university students' attitude towards the four types of university foodservices, and (d) provide recommendations on marketing strategies for university foodservice. Questionnaires were hand delivered to 600 Yonsei University students by designated coordinators. A total of 549 questionnaires were usable; resulting in an 93.3% response rate. The survey was conducted between November 28 to December 4, 1995. Statistical data analysis was completed using the SAS Programs for descriptive analysis, T-test, ${\chi}^2$ test, ANOVA, Factor Analysis and Stepwise Multiple Regression. Most (88.3%) of students were patronizing university foodservices for lunch. Underground student foodservice (40.1%) and Restaurants outside the campus (33.7%) were primarily used for lunch and dinner respectively. Eighty six percent of university students had 1 to 2 meals per day at university foodservices. The reasons given by students for patronizing university foodservices were as follows: location, time, price, menu, taste. Most of the respondents were least satisfied with hygiene, taste, menu and atmosphere. Data indicated strong support for eight priori dimensions in terms of food, menu, atmosphere, hygiene, employee attitude, facilities and convenience. After the factor analysis, price, fast service and foodservice location attributes were rearranged, combined and created a new dimension called as 'access'. Three dimensions in terms of menu, hygiene, convenience were important to students although performance was perceived as poor through importance-performance analysis. Most of students were not satisfied with all four types of university foodservices. In terms of food quality and price which university foodservices offer, most of respondents were moderately satisfied. According to multiple regression analysis, 93.31% of the variance respondents' satisfaction score could be explained by food, menu, price, atmosphere, hygiene, employee attitude, facilities, and convenience dimensions.

• 대한의용생체공학회:의공학회지
• /
• 제24권6호
• /
• pp.501-507
• /
• 2003

환자의 재활을 돕는 보조기 및 의지와 같은 의료기기의 기본 요건 중의 하나는 충분한 강도를 가지도록 설계해야 하는 것이다. 강도설계를 위해서는 먼저 기구에 작용하는 부하를 파악하여야 하는데, 인체에 직접 착용하거나, 인체의 운동을 돕도록 고안된 의료기구의 특성상 정하중 보다는 동하중 형태의 부하를 받는 경우가 많으며, 때때로 충격하중을 받는 경우도 있다. 이같은 형태의 부하를 직접적으로 파악하기 위해서는 구조물에 계측용 센서를 직접 설치하여야 하나, 이럴 경우 센서의 설치로 인한 구조 변경으로 인해 계의 고유 특성을 유지할 수 없는 경우가 흔히 발생하다. 따라서, 이와 같은 경우에는 작용 부하를 간접적으로 즉, 진동 등의 출력으로부터 역으로 구해내는 수 밖에는 없다. 본 논문에서는 이와 같은 동하중 형태의 부하 즉, 작동부하를 구하는 데 있어서 기존 방법인 전달률 방법의 문제점 및 한계점을 살펴보고, 다수개의 기준점을 사용하여 다입력 환경하에서도 적용이 가능한 주성분 분석을 이용한 새로운 방법을 제시하였으며, 실험을 통해 이의 타당성을 검증하였다.

• 한국멀티미디어학회논문지
• /
• 제11권4호
• /
• pp.516-524
• /
• 2008

본 논문은 기존에 연구되지 않았던 옷의 독특한 특징들을 묵시적 제한방법을 사용하여 강력한 제한력으로 구현하는 새로운 모델링 방법을 제안한다. 기존의 명시적 제한방법인 Baumgarte 안정화 방법은 해에 빠르게 수렴하도록 하기 위해 사용자가 시뮬레이션에 따라서 값이 달라지는 안정화 변수 값을 선택해야 하고, 시뮬레이션의 시간 간격 사용에 있어서 안정화에 한계가 있는 단점들이 있다. 본 논문은 큰 시간 간격에도 안정적이고, 안정화 변수 값을 요구하지 않고, 물리적으로도 적합한 물체의 움직임을 보장하는 묵시적 제한방법을 사용한다. 또한 묵시적 제한 방법의 계산 복잡도는 Baumgarte 안정화 방법과 같다. 본 논문은 묵시적 제한방법의 수식과 제한의 오차 분석을 설명하였고 옷의 솔기, 단추, 옷 주름, 옷의 구김, 과잉 늘어짐 방지 등의 복잡한 옷의 요소들에 대한 모델링 방법을 제시하였다. 본 논문에서 제안된 방법은 외부 상황에 의해 각종 제한들이 자동적으로 설정되고 제거되어 계산 비용을 절약함과 동시에 옷의 독특한 특징들의 구현을 통해 현실감 있는 옷 시뮬레이션의 결과들을 얻었다.

• Journal of Nutrition and Health
• /
• 제3권2호
• /
• pp.95-99
• /
• 1970

Korea is one of the typical rice eating countries where availability of animal protein is limited even for the growing generation. Nutritive food products for infants and children are not available commercially in large scale at the present time, although a limited amount of expensive milk products are produced. The present study deals with a pioneering attempt on a new food mixture to meet this demand. Several food mixtures, possibly produced in the country, consisting of rice, soybean, FPC, vitamin, minerals and other food additives are developed in this work Sixty female and male rats aged $30{\sim}40$ days were divided into five groups, twelve rats each. The rats had been maintained with the six different diets, as follow. Formulation of proposed infant food mixturesComposition F-R-1 F-S-2 F-F-3 F-P-4 S Rice 100% 40% 37% 46% 70% Sugar - 12 13 10 70 Casein - - - - 20 Bean - 40 37 24 - Yeast - 3 2 3 - Mineral Vitamain - 2 4 2 4.3 F.P.C - 3 4 7 - Fat - - 4 8 4 Cod liver Oil - - - - 3 The findings of this study presented in FER, PER, final organ weights, body weights growth, percentage of nitrogen retention in the body. F-P-4 group tended to remain the heaviest and F-R-1 the lightest in the body weight among three groups throughout the experimental period. In terms of FER (Feed Efficiency Ratio) and PER (Prortein E. R.) value, F-P-4 group kept the highest record throughout. F-P-4 group showed the highest value of nitrogen retention in the body. In comparision between F-P-4 groups and casein 20% group (standard) in all respects of this experiment, F-P-4 group which is the most superior among experimental group, revealed statisfically no significant inferior than that of standard group. This fact could be interpreted that most limiting a. a., methionine in the soy protein produced little inferiority of the experimental groups in the study.

• 한국지진공학회논문집
• /
• 제2권1호
• /
• pp.79-93
• /
• 1998

철근콘크리트부재가 갖는 균열의 발생, 항복 및 파괴 등의 단계별 역학적 거동의 특성을 정확히 예측하고 모사할 수 있는 해석기법의 개발을 목적으로 하였다. 이를 위해서 균열발생후의 철근과 콘크리트의 부착거동, 균열면에서의 골재의 맞물림 거동 및 철근항복후의 모델링 등에 의해서 반복하중을 받는 철근콘크리트 구조부재의 항복후 파괴거동을 예측할 수 있는 해석모델을 개발하였다. 두께가 서로 다릉 부재간의 접합부에서는 단면강성이 급변하기 때문에 기초의 바닥으로부터 철근의 인발, 접합면의 미끄러짐 및 접합면의 관입 등의 국소적인 불연속 변형이 집중하게 된다. 이와 같은 국소적인 불연속 교각구조의 변형능력에 미치는 기여도는 일반적으로 무시할 수 없는 정도이므로, 불연속 변형을 고려하기 위한 접합요소(joint element)를 도입하였다. 또한 축방향철근 및 횡방향 구속철근의 유무 및 그 양 등에 따른 구속효과를 적절히 표현할 수 있는 해석모델을 개발하였다. 각각의 해석모델들을 조합한 유한요소 해석프로그램에 의한 결과를 다른 연구자들의 결과와 비교하여 타당성을 검증하였다.

• Smart Structures and Systems
• /
• 제9권6호
• /
• pp.505-534
• /
• 2012

The present work deals with second order statistics of post buckling response of piezoelectric laminated composite cylindrical shell panel subjected to hygro-thermo-electro-mechanical loading with random system properties. System parameters such as the material properties, thermal expansion coefficients and lamina plate thickness are assumed to be independent of the temperature and electric field and modeled as random variables. The piezoelectric material is used in the forms of layers surface bonded on the layers of laminated composite shell panel. The mathematical formulation is based on higher order shear deformation shell theory (HSDT) with von-Karman nonlinear kinematics. A efficient $C^0$ nonlinear finite element method based on direct iterative procedure in conjunction with a first order perturbation approach (FOPT) is developed for the implementation of the proposed problems in random environment and is employed to evaluate the second order statistics (mean and variance) of the post buckling load of piezoelectric laminated cylindrical shell panel. Typical numerical results are presented to examine the effect of various environmental conditions, amplitude ratios, electrical voltages, panel side to thickness ratios, aspect ratios, boundary conditions, curvature to side ratios, lamination schemes and types of loadings with random system properties. It is observed that the piezoelectric effect has a significant influence on the stochastic post buckling response of composite shell panel under various loading conditions and some new results are presented to demonstrate the applications of present work. The results obtained using the present solution approach is validated with those results available in the literature and also with independent Monte Carlo Simulation (MCS).

• 약학회지
• /
• 제57권1호
• /
• pp.1-7
• /
• 2013

Induction of effective and increased levels of antibody production may be major points in vaccine development. This is especially the case when the antigenic sources are carbohydrates. Thus, in our Lab various types of formulations such as liposomal and conjugate vaccines have been researched. However, the fastidious formulation process and high costs are a problem. For this reason, there is currently a focus on utilizing immunoadjuvants. In this present study, we tested whether ginsenosides Re (a panaxdiol) and Rg1 (a panaxtriol) from Panax ginseng have immunoadjuvant activity against the cell wall of Candida albicans (CACW). The resulting data showed that Rd and Rg1 caused LPS-treated B lymphocytes to be proliferative. Rd had greater proliferation activity than that of Rg1. In the murine model of antibody production, CACW combined with Rd [CACW/Rd/IFA] or Rg1 [CACW/Rg1/IFA] increased the production of antibodies specific to C. albicans when compared to the antibody production by [CACW/IFA]-induction, which was used as a negative control (P<0.05). In the case of [CFA/Rd/IFA], the antibody production was almost twice as that of the CFA. In addition, formulations containing either had a prolonged antibody inducing activity as compared to the CFA formula. In conclusion, Rd and Rg1 have an immunologic activity, and yet Rd can be a better candidate than Rg1 for a new immunoadjuvant.

• Parasites, Hosts and Diseases
• /
• 제57권1호
• /
• pp.1-8
• /
• 2019

There is no effective treatment modality available against different forms of leishmaniasis. Therefore, the aim of this study was to improve the penetration and efficacy of selenium and glucantime coupled with niosomes and compared them with their simple forms alone on in vitro susceptibility assays. In this study, the niosomal formulations of selenium and in combination with glucantime were prepared. The size and morphology of the niosomal formulations were characterized and the effectivity of the new formulation was also evaluated using in vitro MTT assay, intra-macrophage model, and gene expression profile. From the results obtained, no cytotoxicity effect was observed for niosomal and simple forms of drugs, as alone or in combination. Niosomal formulations of the drugs significantly showed more inhibitory effects ($P{\leq}0.001$) than the simple drugs when the selectivity index was considered. The gene expression levels of Interleukin (IL-10) significantly decreased, while the level of IL-12 and metacaspase significantly increased ($P{\leq}0.001$). The results of the present study showed that selenium plus glucantime niosome possess a potent anti-leishmanial effect and enhanced their lethal activity as evidenced by the in vitro experiments.

• Advances in nano research
• /
• 제7권4호
• /
• pp.241-248
• /
• 2019

Recent researches demonstrated well promising anticancer activities for antibiotics. Such effects would be significantly increased while nanoparticle based delivery systems were applied. In this study, the goal was aim to improve anticancer and antitoxic effects of Streptomycin by loading on special kind of dendrimer (anionic-linear-globular second generation). In the current study, Size and zeta potential as well as AFM techniques have been used to prove the fact that the loading was performed correctly. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the drug loaded on dendrimer nanoparticle were determined and compared with both of dendrimer alone and free drug with respect to staphylococcus aureus as the test microorganism. The anticancer activity among three groups including Streptomycin, Streptomycin -G2 dendrimer, and control was measured in vitro. In vitro studies showed that G2 anionic linear-globular polyethylene-glycol-based dendrimer, which loaded on Streptomycin was able to significantly improve the treatment efficacy over clinical Streptomycin alone with respect to proliferation assay. Maximal inhibitory concentration (IC50) was calculated to be $257{\mu}g/mL$ for streptomycin alone and $55{\mu}g/mL$ for Streptomycin -G2 dendrimer. In addition, Streptomycin -G2 dendrimer conjugate prevented the growth of MCF-7 cancerous cells in addition to enhance the number of apoptotic and necrotic cells as demonstrated by an annexin V-fluorescein isothiocyanate assay. Streptomycin -G2 dendrimer conjugate was able to increase Bcl-2/Bax ratio in a large scale compared with the control group and Streptomycin alone. Based on results a new drug formulation based nano-particulate was improved against S. aureus with sustained release and enhanced antibacterial activity as well as anticancer activity shown for functional cancer treatment with low side effects.