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Calcium phosphate 결정 성장 최적화를 위한 Ti 표면의 BaTiO_3 박막 형성에 관한 연구
조진우,양홍서,박영준,황규석,송종은,이용렬 전남대학교 치과대학 2001 구강과학 Vol.13 No.2
This study was purposed to establish an optimized manufacturing process for a negatively charged ferroelectric thin flim on titanium substrate in order to develop a new implant system having the mechanical strength and bone forming ability. Ferroelectric materials show an alignment of positive and negative charges by poling treatment. Based on this property, this study was performed with the assumption that the Ca^2+ ions would be easily attracted on negatively charged surface and the attracted cation might behave as nuclei for bone-like crystal grownth in biological solutions. In order to have an osteoinducibility by the ferroelectric thin film coating, continuous and flawless crystalline thin film should be formed with ferroelectricity, and finally should be adequately poling treated. In this study, BaTiO_3 (BTO) was selected as a ferroelectric material. Before thin film coating process, most favorable poling condition was investiged with the evaluation of the difference in calcium phosphate (Ca-P) formation in simulated body fluid (SBF). Moreover, the parameters to form an optimum thin film were studied. Dense bulk BTO disks were fabricate using cold isostatic pressing(CIP) and sintered in air at 1300℃ for 2 hours. Sintered BTO disk was polished, and he crystallinity, microstructure, and ferroelectric characteristics were evaluated using an X-ray diffraction analysis (XRD), a field emission scanning electron microscope (FE-SEM), and an Impedance analyzer. To find the optimum poling condition for the calcium phosphate crystal formation, sintered bulk BTO specimens were treated with either of following poling conditions; 1) room temperature poling treatment [ polarizing field (Ep) = 25kV/cm, at 25℃ for 2 hours], 2) under Tc medium-temperaturepoling treatment (Ep=20kV/cm, from 85˚C to 25˚C for 2 hour), and 3) above Tc high-temperature poling were immesed in simulated body fluid (SBF) for 30 days, and the formation of calcium phosphate (Ca-P) layer n the surface was evaluated. The crystallinity, microstructure, and ferroelectric characteristic of BTO thin film were evaluated withthe variation of final heat treatment. It was performed after establishing the starting substance-solvent mixing ratio, coating times, and pre-heating temperature optimal to form continuous and flawless BTO thin film adequate for having ferroelectricity. Perparation of BTO thin film was made by dipping-pyrolysis technique using metal naphthenates as starting substances. BTO thin films was spin-coated on Ti substrate by dipping-pyrolysis technique using sol obtained by mixing Ba-naphthenate and Ti-naphthenate as starting substances. Pre-firing temperature of BTO thin film was performed at 450℃ because organic-solvent ws completely volatilized without any crystal growth, and the final heat treatment was performed at 600, 700 or 800℃, respectively. The results are as follows; 1. BTO disk sintered at 1300℃ for 2 hours showed average grain size of about 1㎛ and the relative dielectric constant at 1㎑ was abut 3000∼3500. 2. After immersing the sintered bulk BTO poled at respective conditions in SBF for 30 days, Ca-P layers were present on the negatively charged surfaces. In contrary, positively charged Bto surface did not show any noticeable charge of the surface microstructure after SBF immersion. 3. In he case of poling condition 1 and 2 treated with below Tc, Ca/P ratio showed a relatively low value of 1,.2∼1.5. While, in the case of poling condition 3 treated with above Tc, Ca/P ratio was 1.5∼1.67, which is similar to that of biological apatite. This phenomenon demonstrates that poling the BTO above the temperature of Tc is preferable for the Ca-P formation. 4. For thin film BTO coastin, the starting substance was prepared by an equimolar mixing of the Ba and Ti-naphthenate. Dilution of the starting substance with toluene was most appropriate at sol : toluene ratio of 5.2:4.8 Too thin sol produced porosity in film, and too thick sol resulted cracks in the film. By repeating the coating and pre-firing procedure 15 times, homogeneous film of 0.5㎛ thickness could be fabricated, and perfomed well during the poling treatment without breakdown. 5. The heat-treatmen of the BTO thin film at 700℃ produced a homogeneous crystalline structure without heterogeneous TiO2 formation. The BTO thin film heat-treated at 600℃ showed non-crystallinity and no ferroelectricity. Treatment at 800℃ produced heterogeneous TiO2 phase in the film, which is unfavorabe for having ferroelectricity by the distortion of the perovskite structure. The relative dielectic constant at 1 ㎑ was 152 and 112 by heat-treatment at 700 and 800℃, respectively. In summary, these results demonstrated that poling the ferroelectric B_aT_iO_3 surface negatively is effective for the formation of Ca-P layer in simulated body fluids. Poling condition at a temperature cooling from above Tc down to room temperature is most effective. By optimizing the method of BTO thin film coating on metal substrate for the formation of Ca-P layer, the data of this study might be applied for the manufacture of new bioactive implant system.
Analysis of Fisetin and Cucurbitacin of Cucumber (Cucumis sativus L.)
So-Jeong Hwang,Yeong-Jee Kim,Jae-Eun Lee,Eun-Ae Yoo,Soo-Kyeong Lee,Ae-Jin Hwang,Hyung-Jun Noh 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10
Cucumber (Cucumis sativus L.) is a crop belonging to the Cucurbitaceae and is a vegetable distributed and consumed around the world. It is known to have pharmacological activities like anticancer, antioxidant because of phytochemical. Fisetin, a polyphenolic phytoconstituent, and cucurbitacin, a group of triterpene compounds, are the most widely known phytochemical of cucumber. This study aim to analyze fisetin and cucurbitacin on cucumber’s edible parts. All of 150 cucumbers germplasm were analyzed of fisetin and four species of cucurbitacin (cucurbitacin E-2-O-glucoside (CuE-Glu), cucurbitacin D (CuD), cucurbitacin I (CuI), cucurbitacin B (CuB)). Samples were stored at -70°C, freeze-dried, and extracted with methanol for analysis by HPLC with DAD. As a result, among 150 total samples, nine of fisetin, two of CuE-Glu, two of CuD, six of CuI, and four of CuB were detected. Amount range of each component was shown as follows (mg/kg): fisetin, 4.98 to 12.74; CuE-Glu, 4.96 to 13.31; CuD, 9.65 to 10.21; CuI, 4.00 to 9.24; CuB, 2.97 to 14.61. In particular, resource no. IT200104 and no. 903729 showed the highest fisetin (12.74 mg/kg) and total cucurbitacin (14.61 mg/kg) content.
윤수민(Yoon, Soo-Min),전소영(Jeon, So-Yeong),황연숙(Hwang, Yeon-Sook) 한국실내디자인학회 2021 한국실내디자인학회논문집 Vol.30 No.4
A subway station is a public space and the complicated way-finding is requested in the subway station because transfer occurs a lot. Therefore a signage system is necessary to support effective and easy way-finding. But many of signage system is usually designed for who have normal visual perception and not for the elderly people. So it is important to apply characteristics of the elderly who have some visual perceptional problem in the aging society. The purpose of this study is to plan the signage system of subway station considering the elderly visual characteristics. The spatial scope is 5 subway station- Jongno 3-ga, Cheongnyangni, Express Terminal, Sadang and Yeonsinnae station and the scope of the elderly is 65 years of age or older. The methods of this study are based on the literature review, field investigation about 5 subway station and interview with the elderly who uses subway station. The results of this study are followed; First, Some of the stations have excessive and deteriorated signage. These cause information overload so it is needed to adjust the ratio of form of signage system. Second, color and pictogram have low consistency. The other way character and form are more proper and have clearer distinction than other factors. However, overall arrangement should be adjusted to satisfy the purpose of information. Third, as a result of interview with the elderly who use the subway station, they prefer receding color for way-finding and this result is different from the literature review. So, an additional interview and research about color combination are needed. This study investigates about the way of signage system design at subway station for the elderly and proposes the practical guideline. Henceforth, subway station should provide more effective signage system design to support the elderly people through following research.
Awareness of chronic obstructive pulmonary disease in current smokers: a nationwide survey
( So Yeong Mun ),( Yong Il Hwang ),( Joo Hee Kim ),( Sung Hoon Park ),( Seung Hun Jang ),( Jae Yong Seo ),( Ja Kyung Kim ),( Yong Bum Park ),( Jae Jung Shim ),( Ki Suck Jung ) 대한내과학회 2015 The Korean Journal of Internal Medicine Vol.30 No.2
Background/Aims: Cigarette smoking is the most common risk factor for chronic obstructive pulmonary disease (COPD). However, few studies of the attitudes toward COPD of smokers, the group at risk of developing this condition, have been conducted. The purpose of this study was to explore the awareness of and attitudes toward COPD of current smokers. Methods: The sample consisted of 502 individuals aged 45 and older from throughout Korea who smoked at least 10 packs of cigarettes per year. Telephone interviews using a structured questionnaire were conducted with respondents. Results: First, we evaluated the health status of subjects, finding that 45.4% considered themselves to be in good health. We also asked about COPD-related symptoms, and 60.6% of subjects reported such symptoms. However, only 1.2% of subjects had been diagnosed with or treated for COPD, only 0.4% spontaneously mentioned COPD as a respiratory disease, and only 26.5% recognized COPD as a respiratory disease after seeing a list of such diseases. Television ranked as the top source of information about COPD. The willingness of 45.0% of subjects to stop smoking increased after being informed about COPD. Conclusions: Despite having COPD-related symptoms, most smokers did not know that COPD is a respiratory disease. The attitudes of smokers toward COPD and smoking cessation varied according to socioeconomic status. In summary, a continuous effort to increase the awareness of COPD among smokers is needed. Additionally, strategies tailored according to different socioeconomic groups will also be necessary.