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Search Results: 1 - 10 of 6888 matches for " Mi-Hyang Cho "
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Age-hardening by grain interior and grain boundary precipitation in an Au-Ag-Pt-Zn-In alloy for multipurpose dental use
Joo-Hee Park,Mi-Hyang Cho,Mi-Gyoung Park,Yong Hoon Kwon,Hyung-Il Kim,Hyo-Joung Seol
Gold Bulletin , 2010, DOI: 10.1007/BF03215001
Abstract: The complex precipitation mechanisms related to the age-hardening of Cu-free Au-Ag-Pt-Zn-In alloy for multipurpose dental use was studied by means of hardness test, X-ray diffraction (XRD) studies, field emission scanning electron microscopic (FE-SEM) observations, energy dispersive spectrometer (EDS) analysis, and electron probe microanalysis (EPMA). The early diffusion and then clustering of the In-concentrated phase in the grain interior, together with the early diffusion and then ordering of the PtZn phase in the grain boundary, introduced the internal strains in the Au-Ag-rich α1 matrix, resulting in the hardening process. As the Au-Ag-rich α 1 ’ and PtZn β lamellarforming grain boundary reaction progressed, the phase boundaries between the solute-depleted face-centered cubic (FCC) α 1 ’ matrix and the face-centered tetragonal (FCT) PtZn β precipitate reduced, resulting in softening. In the particlelike structures composed of the major Pt-Au-rich α2 phase and the minor Pt-Zn-rich α3 phase, the separation of In and Zn progressed producing the In-increased Pt-Au-rich α 2 ’ phase and the Zn-increased PtZn α3′ phase with aging time without restraining the softening. The miscibility limit by complex systems of Au-Pt, Ag-Pt, Au-In and In-Zn resulted in the phase transformation and related microstructural changes.
Age-hardening and overaging mechanisms related to the metastable phase formation by the decomposition of Ag and Cu in a dental Au–Ag–Cu–Pd–Zn alloy
Sang-Hwa Lee,In-Sook Lim,Mi-Hyang Cho,Ae-Ri Pyo,Yong Hoon Kwon,Hyo-Joung Seol,Hyung-Il Kim
Gold Bulletin , 2011, DOI: 10.1007/s13404-011-0021-x
Abstract: The age-hardening and overaging mechanisms related to the metastable phase formation by the decomposition of Ag and Cu in a dental casting gold alloy composed of 56Au–25Ag–11.8Cu–5Pd–1.7Zn–0.4Pt–0.1Ir (wt.%) were elucidated by characterizing the age-hardening behaviour, phase transformations, changes in microstructure and changes in element distribution. The fast and apparent increase in hardness at the initial stage of the aging process at 400°C was caused by the nucleation and growth of the metastable Ag–Au-rich phase and the Cu–Au-rich phase by the miscibility limit of Ag and Cu. The transformation of the metastable Ag–Au-rich phase into the stable Ag–Au-rich phase progressed concurrently with the ordering of the Cu–Au-rich phase into the AuCu I phase through the metastable state, which resulted in the subsequent increase in hardness. The further increase in hardness was restrained before complete decomposition of the parent α0 phase due to the initiation of the lamellar-forming grain boundary reaction. The progress of the lamellar-forming grain boundary reaction was not directly connected with the phase transformation of the metastable phases into the final product phases. The heterogeneous expansion of the lamellar structure from the grain boundary caused greater softening than the subsequent further coarsening of the lamellar structure. The lamellar structure was composed of the Ag–Au-rich layer which was Cu-, Pd- and Zn-depleted and the AuCu I layer containing Pd and Zn.
Analysis of 809 Facial Bone Fractures in a Pediatric and Adolescent Population
Sang Hun Kim,Soo Hyang Lee,Pil Dong Cho
Archives of Plastic Surgery , 2012, DOI: http://dx.doi.org/10.5999/aps.2012.39.6.606
Abstract: Background Facial fractures are infrequent in children and adolescents and have differentclinical features from those in adults. The low incidence in children and adolescents reflectsthe flexibility and underdevelopment of their facial skeletons, as well as their more protectedenvironments. Only a few reports have reviewed such patients in Korea. The authors performeda retrospective study to analyze the characteristics of facial fractures in the Korean pediatricpopulation.Methods We conducted a retrospective review on a series of 741 patients, aged <18 years,with facial fractures who had been treated at our hospital between 2006 and 2010. Thefollowing parameters were evaluated: age, sex, cause, location and type of fractures, associatedinjuries, treatment and complications.Results A total of 741 consecutive patients met the inclusion criteria. The ratio of boys to girlswas 5.7:1. Facial fractures most commonly occurred in patients between 13 and 15 years ofage (36.3%). The most common causes of injury was violence. The nasal fracture was the mostcommon type of fracture (69%) and the blowout fracture was the second most common (20%).Associated injuries occurred in 156 patients (21%).Conclusions The incidence of pediatric facial fractures caused by violence is high in Korea.Our results show that as age increases, etiological factors and fracture patterns gradually shifttowards those found in adults. This study provides an overview of facial fractures in these agegroups that helps illustrate the trends and characteristics of the fractures and may be helpfulin further evaluation and management.
The relationship between cardiovascular disease risk factors and gender  [PDF]
Chung-Min Cho, Young-Mi Lee
Health (Health) , 2012, DOI: 10.4236/health.2012.46051
Abstract: The purpose of this study was to investigate the relationship between three socioeconomic sta- tuses and five behavior-related cardiovascular risk factors by gender, based on data from the Third Korea National Health and Nutrition Examination III. Data from 4556 people were analyzed. The propensity toward obesity, hypercholesterolemia, and physical inactivity was significantly higher in women than in men. Hypertension and smoking were significantly more prevalent in men than in women. The differences in the prevalence of cardiovascular disease risk factors by gender is important and should be considered when developing programs to reduce the incidence of cardiovascular diseases.
The Application of the Korean Dietary Pattern Score; KNHANES (Korean National Health and Nutrition Examination Survey) 2007  [PDF]
Kyung Won Lee, Ji Eun Oh, Mi Sook Cho
Food and Nutrition Sciences (FNS) , 2012, DOI: 10.4236/fns.2012.312221
Abstract: The aim of this study was to apply the Korean Dietary Pattern Score (KDPS) to Korean subjects based on traditional Korean-style meals. The KDPS is based on the 3-Chup Bansang (the traditional Korean daily table setting) and considers the intake of 6 major food groups according to the Korean Dietary Reference Intakes (KDRIs). The KDPS consists of 2 parts: the Korean-Style Meal Score (KSMS) and the Food Group Score (FGS). The KDPS was applied dietary data collected during the Korean National Health and Nutrition Examination Survey (KNHANES) in 2007. Socio-demographic status, gender, age, and body mass index are all factors that have been shown to be meaningful predictors for the KDPS. When the effect of the KDPS on risk of disease was evaluated, a higher total KDPS was associated with a decreased risk of elevated systolic blood pressure (p < 0.05) and hypercholesterolemia (p < 0.05). In addition, as the KSMS increased, the risk of central obesity (p < 0.05) and hypertension (p < 0.01) significantly decreased. A higher total KDPS suggests a greater diversity of food intake, and therefore greater dietary diversity appears to lower the risk of disease. The KDPS is relevant because it integrates scores for Korean-style meal patterns and meal evaluation from a nutritional perspective. In conclusion, the KDPS is appropriate for evaluating the quality of diet, adherence to Korean-style meal patterns, and risk of related diseases. These results will be useful for evaluating the nation’s dietary patterns, nutrition, and health status when planning nutrition policies and programs.
Electrical Characteristics of Poly(ethylene oxide)-urea Complex Films
Mi Yeon Cho,Kyoungah Cho,Sangsig Kim
Transactions on Electrical and Electronic Materials , 2012,
Abstract: The electrical characteristics of complex films composed of poly(ethylene oxide) (PEO) and urea as a function ofthe urea concentration were examined in this study. Moreover, their structural characteristics were also compared.Depending on the urea concentration, the structural phases were classified as PEO+β-phase composite, β-phase+α-phase composites, or α-phase composite+urea. At urea concentrations below ~0.064 M, the β-phase was dominant inthe complex film. Moreover, the conductance increased rapidly with an increase in the urea concentration. For ureaconcentrations ranging from ~0.064 to ~0.25 M, the β-phase was gradually substituted by the α-phase. As the film wascomposed entirely of the α-phase at urea concentrations greater than ~0.25 M, its conductance was decreased. In thisstudy, the electrical characteristics observed for the different phases are analyzed and discussed.
Weak value measurement with an incoherent measuring device
Young-Wook Cho,Hyang-Tag Lim,Young-Sik Ra,Yoon-Ho Kim
Physics , 2009, DOI: 10.1088/1367-2630/12/2/023036
Abstract: In the Aharonov-Albert-Vaidman (AAV) weak measurement, it is assumed that the measuring device or the pointer is in a quantum mechanical pure state. In reality, however, it is often not the case. In this paper, we generalize the AAV weak measurement scheme to include more generalized situations in which the measuring device is in a mixed state. We also report an optical implementation of the weak value measurement in which the incoherent pointer is realized with the pseudo-thermal light. The theoretical and experimental results show that the measuring device under the influence of partial decoherence could still be used for amplified detection of minute physical changes and are applicable for implementing the weak value measurement for massive particles.
Relative performance of different exposure modeling approaches for sulfur dioxide concentrations in the air in rural western Canada
Igor Burstyn, Nicola M Cherry, Yutaka Yasui, Hyang-Mi Kim
BMC Medical Research Methodology , 2008, DOI: 10.1186/1471-2288-8-43
Abstract: We explored how accurately location-specific mean concentrations of SO2 can be predicted for 2002 at 666 locations with multiple measurements. Means of repeated measurements on the 666 locations in 2002 were used as the alloyed gold standard (AGS). First, we considered two approaches: one that uses one measurement from each location of interest; and the other that uses context data on proximity of monitoring sites to putative sources of emission in 2002. Second, we imagined that all of the previous year's (2001's) data were also available to exposure assessors: 9,464 measurements and their context (month, proximity to sources). Exposure prediction approaches we explored with the 2001 data included regression modeling using either mixed or fixed effects models. Third, we used Bayesian methods to combine single measurements from locations in 2002 (not used to calculate AGS) with different priors.The regression method that included both fixed and random effects for prediction (Best Linear Unbiased Predictor) had the best agreement with the AGS (Pearson correlation 0.77) and the smallest mean squared error (MSE: 0.03). The second best method in terms of correlation with AGS (0.74) and MSE (0.09) was the Bayesian method that uses normal mixture prior derived from predictions of the 2001 mixed effects applied in the 2002 context.It is likely that either collecting some measurements from the desired locations and time periods or predictions of a reasonable empirical mixed effects model perhaps is sufficient in most epidemiological applications. The method to be used in any specific investigation will depend on how much uncertainty can be tolerated in exposure assessment and how closely available data matches circumstances for which estimates/predictions are required.It is well established that errors in exposure estimation can bias the results of epidemiological investigations. This takes most commonly the form of attenuation of the exposure-response association such that
Estimation methods with ordered exposure subject to measurement error and missingness in semi-ecological design
Kim Hyang-Mi,Park Chul Gyu,van Tongeren Martie,Burstyn Igor
BMC Medical Research Methodology , 2012, DOI: 10.1186/1471-2288-12-135
Abstract: Background In epidemiological studies, it is often not possible to measure accurately exposures of participants even if their response variable can be measured without error. When there are several groups of subjects, occupational epidemiologists employ group-based strategy (GBS) for exposure assessment to reduce bias due to measurement errors: individuals of a group/job within study sample are assigned commonly to the sample mean of exposure measurements from their group in evaluating the effect of exposure on the response. Therefore, exposure is estimated on an ecological level while health outcomes are ascertained for each subject. Such study design leads to negligible bias in risk estimates when group means are estimated from ‘large’ samples. However, in many cases, only a small number of observations are available to estimate the group means, and this causes bias in the observed exposure-disease association. Also, the analysis in a semi-ecological design may involve exposure data with the majority missing and the rest observed with measurement errors and complete response data collected with ascertainment. Methods In workplaces groups/jobs are naturally ordered and this could be incorporated in estimation procedure by constrained estimation methods together with the expectation and maximization (EM) algorithms for regression models having measurement error and missing values. Four methods were compared by a simulation study: naive complete-case analysis, GBS, the constrained GBS (CGBS), and the constrained expectation and maximization (CEM). We illustrated the methods in the analysis of decline in lung function due to exposures to carbon black. Results Naive and GBS approaches were shown to be inadequate when the number of exposure measurements is too small to accurately estimate group means. The CEM method appears to be best among them when within each exposure group at least a ’moderate’ number of individuals have their exposures observed with error. However, compared with CEM, CGBS is easier to implement and has more desirable bias-reducing properties in the presence of substantial proportions of missing exposure data. Conclusion The CGBS approach could be useful for estimating exposure-disease association in semi-ecological studies when the true group means are ordered and the number of measured exposures in each group is small. These findings have important implication for cost-effective design of semi-ecological studies because they enable investigators to more reliably estimate exposure-disease associations with smaller exposure mea
Efficacy of Lactic Acid Bacteria (LAB) supplement in management of constipation among nursing home residents
Hyang An, Eun Baek, Seok Jang, Do Lee, Mi Kim, Jung Kim, Kang Lee, Jong Park, Nam Ha
Nutrition Journal , 2010, DOI: 10.1186/1475-2891-9-5
Abstract: Nineteen subjects (8M, 11F; mean age 77.1 ± 10.1) suffering with chronic constipation were assigned to receive LAB (3.0 × 1011 CFU/g) twice (to be taken 30 minutes after breakfast and dinner) a day for 2 weeks in November 2008. Subjects draw up a questionnaire on defecation habits (frequency of defecation, amount and state of stool), and we collected fecal samples from the subjects both before entering and after ending the trial, to investigate LAB levels and inhibition of harmful enzyme activities. Results were tested with SAS and Student's t-test.Analysis of questionnaire showed that there was an increase in the frequency of defecation and amount of stool excreted in defecation habit after LAB treatment, but there were no significant changes. And it also affects the intestinal environment, through significantly increase (p < 0.05) fecal LAB levels. In addition, tryptophanase and urease among harmful enzyme activities of intestinal microflora were significantly decreased (p < 0.05) after LAB treatment.LAB, when added to the standard treatment regimen for nursing home residents with chronic constipation, increased defecation habit such as frequency of defecation, amount and state of stool. So, it may be used as functional probiotics to improve human health by helping to prevent constipation.Constipation is prevalent in modern societies and is a common symptom in clinical practice [1].Constipation involves the large intestine and is a symptom rather than a disease. It is characterized by a constellation of symptoms and complaints, the most common of which are low defecation frequency (e.g. less than 3/week), irregular stool expulsion, painful and strained defecation, hard and dry stool consistency, a feeling of incomplete rectal defecation, and passing of abnormally small stools (e.g. less than 50 g/day) [2].The prevalence of constipation and its impact on quality of life are most significant among elderly individuals, with a reported incidence among ambulatory adult
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