• Transactions on Electrical and Electronic Materials
• /
• v.7 no.3
• /
• pp.112-117
• /
• 2006

In this paper we present that the effects of polymer adsorption on stabilities and CMP performance of ceria abrasive particles. Characterization of ceria abrasive particles in the presence of poly(vinyl pyrrolidone) (PVP) was performed by the measurements of adsorbed amounts of PVP, average sizes, and the back scattering intensities of the ceria abrasive particles as functions of PVP molecular weight and PVP concentration. The ceria abrasive particles in the presence of PVP were used to polish $SiO_2\;and\;Si_3N_4$ films deposited on Si wafers in order to understand the effect of PVP adsorption on chemical mechanical polishing (CMP) performance, together with ceria abrasive particles without PVP. Adsorption of PVP on the ceria abrasive particles enhanced the stability of ceria abrasive particles due to steric stabilization of the thick adsorbed layer of PVP. Removal rates of the deposited $SiO_2\;and\;Si_3N_4$ films by the ceria abrasive particles in the presence of PVP were much lower than those in the absence of PVP and their magnitudes were decreased with an increase in the concentration of free PVP chains in the dispersion media. This suggests that the CMP performance in the presence of PVP could be mainly controlled by the hydrodynamic interactions between the adsorbed PVP chains and the free ones. Moreover, the molecular weight dependence of PVP on the removal rates of the deposited films was hardly observed. On the other hand, high removal rate selectivity between the deposited films in the presence of PVP was not observed.

• Asian Journal of Turfgrass Science
• /
• v.10 no.4
• /
• pp.315-329
• /
• 1996

The changes of growth and protein synthesis pattern by aluminum (Al), cadmium (Cd), zinc (Zn) treatments were studied in Cyanobacterium synechocystis sp. PCC 6803. When exposed to Al from 5ppm to 3oppm, synechocystis grows normally. But more than that retard the growth of algae notably. The 0.05ppm Cd additions had no effect on the growth of algae. 0.1, 0.2, and 0.5ppm Cd inhibited growth. Under 1 and 2ppm Cd stress, growth was greatly diminished. Zn had dual effects. The growth of algae in media containing 5ppm was stimulated. As concentration increases more than l5ppm, growth inbition increases. Under 25ppm Zn stress, growth was greatly diminished. According to logistic theory, r and K values of each heavy metal-treated groups were estimated. Correlation analysis of r and K values with metal concentration shows that there is negative correlation between K and concentration in Cd and Zn treatments. Critical concentration which shows lethal or sublethal effect was estimated by t-test of each r and K value. The cells cultured in 10, 20, 30, 40 and 5oppm of Al, 1 and 2ppm of Cd, and 10, 15, 20, 25 and 30ppm of Zn for 4 days was used for protein analysis. Analysis of protein synthesis with SDS-PACE showed alterations of protein synthesis pattern. The synthesis of protein about 220kD increased markedly. In this study, it showed that resistance mechanism against Al, Cd, and Zn is K selection and that metal stress induced the change of protein synthesis in Cyanobacterium synechocystis sp. PCC 6803.Key words:Cyanobacterium synechocystis sp. FCC 6803, Heavy metals, Aluminum, Cadmiutm Zinc, Crowth, Frotein synthesis.

• Korean Journal of Plant Resources
• /
• v.19 no.4
• /
• pp.524-529
• /
• 2006

In vitro culture system was established to induce multiple shoots of Albizzia julibrissin Duraz. by investigating the effects of cytokinins. Cotyledon, hypocotyl and root explants were cultured on MS media supplemented with either three different plant growth regulators or their combinations. The most effective cytokinin sources were zeatin 2.0 + TDZ 0.5 mg/L in cotyledon, zeatin 1.0 mg/L in hypocotyl, and BA 0.2 + TDZ 0.01 mg/L in root explant for producing shoots ($5.67\;{\pm}\;1.20$, $19.50\;{\pm}\;3.50$, and $20.50\;{\pm}\;2.47$, respectively). Also, zeatin treatment was tended to induce more shoots rather than the combinations of other cytokinins. In addition, the root induced in 1/2 MS medium without any plant growth regulators was longer and thicker than treatments of IBA, NAA, IAA and 2.4-D as auxins. Overall, the highest average percent of in vitro shoot formation was 73% from three different types of explants with treatment of zeatin (1.0mg/L).

• 전자공학회논문지 IE
• /
• v.48 no.1
• /
• pp.36-44
• /
• 2011

The purpose of this study was to develop the basic design principles for the engineering mathematics teaching model that supported college students to become collaborative problem solvers. For this purpose, the following four design principles were drawn from the steps of systems approach, especially with consideration of needs of engineering students, professors, curriculum and relevant research on mathematical education. As a result, the four design principles for the engineeering mathematics teaching model were drawn as follows: (1) Improve students' basic mathematical learning abilities through repetition and elaborative practice of the basic mathematical concepts and principles, (2) Develop students' problem solving abilities through collaborative projects or learning activities with peers, (3) Facilitate students' reflection and provide teacher's monitoring and prompt feedback during their learning process, and (4) Build up online learning environments that enable students to become self-regulated learners.

• Child Health Nursing Research
• /
• v.2 no.2
• /
• pp.35-44
• /
• 1996

The purpose of this study was to examine the knowledge and attitude of breast feeding and to explore the predictive variables for the intention of breast feeding of mothers. One hundred and thirty-five mothers who delivered at the D University hospital during the period of May to June in 1996 comprised the sample. Data were collected by questionnaire methods before discharge at the hospital. Data were analyzed using percent, 1-test, and logistic regression. The results were as follows : 1. During their pregnancy, majority of mothers (74.8%) got the breast feeding information. Information sources were book (34.5%), family and relatives(32.4%), mass media(24.3%), and professionals such as nurses and doctors (8.8% ). The frequently reported sources of most encouragement for breast feeding were mother in law(20.7%) and baby's father (11.1% ). 2. The mean score of the items of Knowledge and Attitude toward Breast Feeding Scale were 42.56 (SD=5.47) and 39.07(SD=5.15) , representing positive attitude toward breast feeding. The correlation between knowledge and attitude score was significant(r 〓.54, p<.001). Knowledge of breast feeding were significantly different between breast feeding intention group (including partial breast feeding) and artificial feeding intention group(t=2.79, p<.01) 3. Logistic regression analysis revealed that feeding method in the hospital, delivery type, knowledge toward breast feeding, disease related to pregnancy, complication related to delivery, and educational level of mother were predictives of the intention of breast feeding. 4. The most frequently rated reasons for the plan for mixed feeding were concern about insufficient milk (37.9%) and work(27.6%), The major reasons for plan for artificial milk feeding were having premature baby(25.9%) and maternal health problems including infection(14.8% ) and drug use due to chronic illness (14.8%). From the result of the study, it is recommended to develop supportive nursing intervention strategy to promote breast-feeding intention and practice. The intervention could be more effective to begin early in pregnancy and include teaching for breast feeding skills as well as information provision for positive attitude formation.

• Reproductive and Developmental Biology
• /
• v.28 no.1
• /
• pp.7-12
• /
• 2004

This study was performed to establish the effective culture condition for the establishment of clonal lines from porcine fetal fibroblast cells. Fibroblasts derived from a pig fetus (Day 50) were cultured and passaged two times before use. A single cell was seeded in 96-well plates, cultured in medium supplemented with different concentrations of FBS, catalase or $\beta$-mercaptoethanol ($\beta$ME), and classified by cell size and morphology. Cells were passaged two times into 4-well dish before freezing. The establishment efficiencies were not different among different concentrations of FBS (0.3 to 5.1%). However, population doubling time (PDT) was significantly decreased by increasing the FBS concentration (P＜0.05). The establishment efficiency of $\beta$ME-added group (10.4%) was significantly higher than those of catalase-added and control groups (3.5%, and 3.5%, respectively, p＜0.05), and PDT was significantly decreased (23.6 vs 28.1, and 25.5 h, respectively, p＜0.05). However, catalase did not show a positive effect on the establishment efficiency. Cell size and morphology did not affect the establishment efficiency and PDT of clonal lines. The result of present study shows that the establishment efficiency of clonal cell lines can be enhanced by the culture in media supplemented with 30% FBS and $\beta$ME.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2003.10a
• /
• pp.59-67
• /
• 2003

An efficient plant regeneration system was developed for Hordeum vulgare L. cv Baegdong - an important Korean cultivar. The protocol was based on a series of experiments involving the sizes of mature embryos and the culture media. The embryo size is found to be critical for the establishment of embryogenic callus. Embryos of 1.1-1.5 mm size showed a much higher ability to produce embryogenic callus capable of regenerating green plants. The auxins picloram and dicamba proved effective in inducing callus from mature embryos. $2.5\;m;I^{-1}$ dicamba and $4.0\;mg\;I^{-1}$ picloram in Murashige and Skoog's (MS) medium was optimum for the induction of primary callus. The induced primary callus was loose and friable which ultimately developed into creamy white and compact callus after transferring into the fresh medium. Multiple shoots were induced in the MS medium supplemented with $6.0\;g\;I^{-1}$ maltose, $20\;mg\;I^{-1}$ sorbitol, $0.5\;mg\;I^{-1}$ 2, 4-D and $1.0\;mg\;I^{-1}$ kinetin and the rate was 6.5 shoots per embryo. Regenerated plants were hardy and developed roots rapidly in the medium containing $0.2\;I^{-1}$ IBA. This efficient plant regeneration system provides a foundation for generating transgenic plants of this important barley cultivar.

• Journal of the Optical Society of Korea
• /
• v.17 no.4
• /
• pp.344-349
• /
• 2013

This paper proposes a simulation algorithm to assess the gradual yellowing vision of the elderly, which refers to the predominance of yellowness in their vision due to aging of the ocular optic media. This algorithm employed the spectral transmittance property of a yellow filter to represent the color appearance perceived by elderly people with yellow vision, and modeled the changes in the color space through a spectrum change in light using the yellow filter effect. The spectral reflectivity data of 1269 Munsell matte color chips were used as reference data. Under the standard conditions of a D65 illuminant and a $10^{\circ}$ observer of 1964 CIE, the spectrum of the 1269 Munsell colors were processed through the yellow filter effect to simulate yellow vision. Various degrees of yellow vision were modeled according to the transmittance percentage of the yellow filter. The color differences before and after the yellow filter effect were calculated using the DE2000 formula, and the color pairs were selected based on the color difference function. These color pairs are distinguishable through normal vision, but the color difference diminishes as the degree of yellow vision increases. Assuming 80% of yellow vision effect, 17 color pairs out of $(1269{\times}1268)/2$ pairs were selected, and for the 90% of yellow vision effect, only 3 color pairs were selected. The result of this study can be utilized for the diagnosis system of gradual yellow vision, making various types of test charts with selected color pairs.

• Healthcare Informatics Research
• /
• v.24 no.4
• /
• pp.292-299
• /
• 2018

Objectives: The aim of the present study was to assess the frequency of use, and preferences regarding information and communication technologies (ICTs) among Ecuadorian patients with chronic kidney disease (CKD) undergoing hemodialysis. Methods: We conducted an anonymous cross-sectional survey-based study from January 2016 to April 2017, involving 393 patients with end-stage renal disease from 9 hemodialysis centers, in which they rated their use and preferences of various ICTs through a modified version of the Michigan Questionnaire. The questionnaire collected information regarding demographics, patients' interest in obtaining health-related information through ICTs, and interest in using ICTs as a potential way to communicate with their healthcare providers. A chi-square test for association and adjusted regression analyses were performed. Results: Among all patients who participated, 64.3% reported owning a cellphone, with less than a third reporting active Internet connection. The most used ICT for obtaining information about CKD and/or hemodialysis was web-based Internet, followed by YouTube. SMS was rated the highest to receive and seek health-related information, followed by Facebook. Younger age and higher levels of education were associated with a higher overall usage of ICTs. Finally, more than half of the patients reported interest in using WhatsApp for communicating with their healthcare providers. Conclusions: Understanding the preferences of ICTs among patients with CKD undergoing hemodialysis could help to improve their outcomes through the potential uses and benefits of ICTs. Further research is needed to assess their role in improving the care of patients with chronic diseases.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.32 no.4
• /
• pp.359-370
• /
• 2022

Objective: This study is intended to design a commercially available passive sampler and conduct performance test on its use as a media for evaluating a working environment. Methods: This study was conducted to select adsorbents, design models, and evaluate storage stability and sampling rates for the development of new types of passive samplers. Results: The impurity detection, adsorbent capacity and breakthrough volume of five types of activated carbon were tested for selection of an adsorbent. One product was selected in consideration of the efficiency of purchase. A number of passive samplers were designed in a radial style and a badge style using plastic as a material. The final two prototypes were made using molds or 3D printing. For the storage stability evaluation, samples were stored at different temperature for 1~21 days and then analyzed. Most of the chemicals had excellent storage stability when refrigerated. However, some chemicals such as dichloromethane and methyl ethyl ketone need to be analyzed as soon as possible after sampling. Conclusion: In this study, new types of passive samplers for 66 chemical compounds were developed. The evaluation of storage stability and sampling rates showed different results depending on the properties of the chemical substance. For some chemicals such as methyl ethyl ketone and dimethylformamide, activated carbon is inappropriate as an absorbent. In future studies, additional experiments are required on chemicals that are difficult to collect with activated carbon.