• The Journal of the Korean dental association
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• v.48 no.3
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• pp.196-204
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• 2010

To establish the ideal occlusal relationship, the values of tooth size and ratio must be in a normal range. In this study, the means and standard deviations of Bolton's anterior ratio and overall ratio using mesiodistal dimensions of teeth measured on diagnostic models of 334 Korean malocclusion patients were calculated and differences in Bolton ratio according to the groups of malocclusion patients were studied. Also the changes that can occur in overall ratio before and after hypothetical tooth extractions were observed. The results are as follows. 1. The mean anterior ratio of Korean malocclusion patients was $78.0\;{\pm}\;2.69%$, and the mean overall ratio was $91.56\;{\pm}\;2.28%$. 2. The largest value of tooth size ratio could be found in Class III group, followed by Class I and Class II groups in order. However there was no statically significant difference. 3. The values of overall ratio reduced significantly after premolar extractions in all malocclusion groups, which was much more significant in the extraction of upper second premolar and lower first premolar(U5L4) or upper second premolar and lower second premolar(U5L5). 4. The values of overall ratio reduced significantly after premolar extractions in all 3 groups divided based on Bolton ratio, which was much more significant in the extraction of upper second premolar and lower first premolar(U5L4) or upper second premolar and lower second premolar(U5L5).

• Structural Engineering and Mechanics
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• v.64 no.5
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• pp.621-640
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• 2017

This paper reports the numerical investigation conducted to study the influence of Local-Distortional (L-D) interaction mode buckling on post buckling strength erosion in fixed ended lipped channel cold formed steel columns. This investigation comprises of 81 column sections with various geometries and yield stresses that are carefully chosen to cover wide range of strength related parametric ratios like (i) distortional to local critical buckling stress ratio ($0.91{\leq}F_{CRD}/F_{CRL}{\leq}4.05$) (ii) non dimensional local slenderness ratio ($0.88{\leq}{\lambda}_L{\leq}3.54$) (iii) non-dimensional distortional slenderness ratio ($0.68{\leq}{\lambda}_D{\leq}3.23$) and (iv) yield to non-critical buckling stress ratio (0.45 to 10.4). The numerical investigation is carried out by conducting linear and non-linear shell finite element analysis (SFEA) using ABAQUS software. The non-linear SFEA includes both geometry and material non-linearity. The numerical results obtained are deeply analysed to understand the post buckling mechanics, failure modes and ultimate strength that are influenced by L-D interaction with respect to strength related parametric ratios. The ultimate strength data obtained from numerical analysis are compared with (i) the experimental tests data concerning L-D interaction mode buckling reported by other researchers (ii) column strength predicted by Direct Strength Method (DSM) column strength curves for local and distortional buckling specified in AISI S-100 (iii) strength predicted by available DSM based approaches that includes L-D interaction mode failure. The role of flange width to web depth ratio on post buckling strength erosion is reported. Then the paper concludes with merits and limitations of codified DSM and available DSM based approaches on accurate failure strength prediction.

• Microbiology and Biotechnology Letters
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• v.24 no.2
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• pp.149-154
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• 1996

Effect of glucose addition to xylose medium on xylitol production was investigated by using Candida parapsilosis ATCC 21019 mutant. With increasing the ratio of glucose to xylose in total amount of 50 g/l as glucose and/or xylose, xylitol production was decreased but ethanol and glycerol production were increased. Ethanol and glycerol concentration were maxmum in 10 g/l of xylose and 40 g/l of glucose medium as 21.5 g/l and 3.6 g/l, respecti- vely. No xylitol was formed in glucose medium without xylose because xylitol could be not produced from glucose. With increasing the ratio of glucose to xylose, the activity of xylose reductase which converted xylose to xylitol were decreased. The activities of xylitol dehydrogeiiase which converted xylitol to xylulose and then cell materials were found to be constant regardless of the ratio of glucose to xylose. This results indicated that glucose addition to xylose medium on cell growth was not affected. In order to prevent the inhibitory effect of glucose on xylitol production, glucose in a fermentor was fed with low concentration and then ethanol and glycerol was critically decreased and the xylitol yield from xylose of the culture with glucose feeding was recovered the almost same as that with only 50 g/l of xylose. However, the xylitol yield from total sugars (xylose and glucose) was decreased and glucose was not contributed to xylitol production. Therefore, the fermentation at high concentration of xylose without glucose was carried out. A final xylitol concentration of 242 g/l which corresponding 80.7% of xylitol yield was obtained from 300 g/l of xylose for 273 hours.

• Korean Journal of Radiology
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• v.20 no.4
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• pp.621-630
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• 2019

Objective: To study the prevalence and clinical characteristics of decreased myocardial blood flow (MBF) quantified by dynamic computed tomography (CT) myocardial perfusion imaging (MPI) in symptomatic patients without in-stent restenosis. Materials and Methods: Thirty-seven (mean age, 71.3 ± 10 years; age range, 48-88 years; 31 males, 6 females) consecutive symptomatic patients with patent coronary stents and without obstructive de novo lesions were prospectively enrolled to undergo dynamic CT-MPI using a third-generation dual-source CT scanner. The shuttle-mode acquisition technique was used to image the complete left ventricle. A bolus of contrast media (50 mL; iopromide, 370 mg iodine/mL) was injected into the antecubital vein at a rate of 6 mL/s, followed by a 40-mL saline flush. The mean MBF value and other quantitative parameters were measured for each segment of both stented-vessel territories and reference territories. The MBF_ratio was defined as the ratio of the mean MBF value of the whole stent-vessel territory to that of the whole reference territory. An MBF_ratio of 0.85 was used as the cut-off value to distinguish hypoperfused from non-hypoperfused segments. Results: A total of 629 segments of 37 patients were ultimately included for analysis. The mean effective dose of dynamic CT-MPI was 3.1 ± 1.2 mSv (range, 1.7-6.3 mSv). The mean MBF of stent-vessel territories was decreased in 19 lesions and 81 segments. Compared to stent-vessel territories without hypoperfusion, the mean MBF and myocardial blood volume were markedly lower in hypoperfused stent-vessel territories (77.5 ± 16.6 mL/100 mL/min vs. 140.4 ± 24.1 mL/100 mL/min [p < 0.001] and 6.4 ± 3.7 mL/100 mL vs. 11.5 ± 4 mL/100 mL [p < 0.001, respectively]). Myocardial hypoperfusion in stentvessel territories was present in 48.6% (18/37) of patients. None of clinical parameters differed statistically significantly between hypoperfusion and non-hypoperfusion subgroups. Conclusion: Decreased MBF is commonly present in patients who are symptomatic after percutaneous coronary intervention, despite patent stents and can be detected by dynamic CT-MPI using a low radiation dose.

• Polymer(Korea)
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• v.24 no.4
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• pp.445-452
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• 2000

The copolymerization of ethylene (E) and norbornene (N) was examined by using various metallocene catalysts and modified-MAO(MMAO) cocatalyst. For $C_2$-symmetry catalysts such as rac-Et(Ind)$_2$ZrC $l_2$, M $e_2$Si(Ind)$_2$ZrC $l_2$, M $e_2$Si(Cp)$_2$ZrC $l_2$ and Cs-symmetrical iPr(FluCp)ZrC $l_2$ as well as CGC and di-bridged zirconocene, the effects of catalyst structure and [N]/[E] feed ratio on catalyst activity, thermal property and [N] content of copolymer (COC) was investigated. For rac-Et(Ind)$_2$ZrC $l_2$ catalyst of a constant [N]/[E] feed ratio, the appropriate conditions of [Al]/[Zr] mole ratio, polymerization temperature and cocatalyst structure were found to be 3000, 4$0^{\circ}C$, MMAO cocatalyst, respectively. As [N]/[E] feed ratio increased, the incorporation of norbornene to copolymer increased while, the activity of catalyst decreased except for iPr(FluCp)ZrC $l_2$ With consideration of catalyst activity as well as N content, it was found that rac-Et(Ind)$_2$ZrC $l_2$/MMAO system exhibited relatively high activity and controllable $T_{g}$. Monomer reactivity ratio was determined by Kelen-Tudos method..

• Journal of Environmental Science International
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• v.19 no.7
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• pp.871-877
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• 2010

The objectives of this study were to compare growth of Pllioblastus pygmaed and soil characteristics as affected by difference of soil thickness and mixture ratio in shallow-extensive green roof module system, and to identify the level of soil thickness and mixture as suitable growing condition to achieve the desired plants in green roof. Different soil thickness levels were achieved under 15cm and 25cm of shallow-extensive green roof module system that was made by woody materials for $500{\times}500{\times}300mm$. Soil mixture ratio were three types for perlit: peatmoss: leafmold=6:2:2(v/v/v, $P_6P_2L_2$), perlit: peatmoss: leafmold=5:3:2(v/v/v, $P_5P_3L_2$) and perlit: peatmoss: leafmold=4:4:2(v/v/v, $P_4P_4L_2$). On June 2006, Pllioblastus pygmaed were planted directly in a green roof module system in rows. All treatment were arranged in a randomized complete block design with three replication. The results are summarized below. In term of soil characteristics, Soil acidity and electric conductivity was measured in pH 6.0~6.6 and 0.12dS/m~0.19dS/m, respectively. Organic matter and exchangeable cations desorption fell in the order: $P_4P_4L_2$ > $P_5P_3L_2$ > $P_6P_2L_2$. $P_6P_2L_2$ had higher levels of the total solid phase and liquid phase, and $P_4P_4L_2$ had gas phase for three phases of soil in the 15cm and 25cm soil thickness. Although Pllioblastus pygmaed was possibled soil thickness 15cm, there was a trend towards increased soil thickness with increased leaf length, number of leaves and chlorophyll contents in 25cm. The growth response of Pllioblastus pygmaed had fine and sustain condition in order to $P_6P_2L_2$ = $P_5P_3L_2$ > $P_4P_4L_2$. However, The results of this study suggested that plants grown under $P_4P_4L_2$ appear a higher density ground covering than plants grown under $P_6P_2L_2$. Collectively, our data emphasize that soil thickness for growth of Pllioblastus pygmaed were greater than soil mixture ratio in shallow-extensive green roof module system.

• Development and Reproduction
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• v.12 no.1
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• pp.57-66
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• 2008

Changes in luteinizing hormone (LH), serum testosterone (T), and salivary T levels with age were examined in Korean men. Serum was obtained from 167 Korean men of different ages ($20{\sim}69\;y$), and the serum LH and T levels were measured. Saliva samples were also obtained, and the salivary T level was determined. The LH levels did not change considerably until 40 y of age (20s, $2.5{\pm}1.0$; 30s, $2.7{\pm}1.5$; and 40s, $2.5{\pm}1.8\;mIU/mL$) but increased significantly around 50 y (50s, $3.7{\pm}1.8$ and 60s, $3.1{\pm}1.7\;mIU/mL$). Further, the serum T levels also did not change until 40 y of age (20s, $5.3{\pm}2.6$, 30s, $4.4{\pm}1.4$, 40s, $4.1{\pm}1.5\;ng/mL$) but decreased significantly at 50 y (50s, $3.4{\pm}1.5$; 60s, $2.6{\pm}0.8\;ng/mL$). The salivary T levels also showed small changes until the age of 40 y ($20s{\sim}40s$, $0.11{\pm}0.015\;ng/mL$) but decreased significantly at 50 y ($0.08{\pm}0.03\;ng/mL$). Thus, the relative ratio of salivary T to serum T levels did not change significantly in all the ages examined ($2.4{\pm}0.9%$). Linear regression analysis predicted that the LH levels increased 1.5%/y while the serum and salivary T levels decreased 1%/y and 0.8%/y, respectively. The serum T/LH ratio did not change considerably until the age of 40 y ($20s{\sim}40s$, $2.27{\pm}0.14$) but decreased significantly ($1.2{\pm}1.0$) at 50 y. Age-related changes in the salivary T/LH ratio were very similar to those in the serum T/LH ratio. These results demonstrated that LH and T levels in serum or saliva did not change considerably until 40 y of age; instead, in Korean men, from 50 y of age, the LH level increased, while the T level decreased. This suggests that primary testicular failure that occurred due to aging (approximately 50 y) and caused this phenomenon. The present study also shows that the salivary T level can be an indicator of the free T level in serum although the salivary T level correlates weakly with the total T level in serum (r=0.53). Thus, information regarding salivary T levels may be useful for studying the age-related changes occurring in male testicular physiology.

• Progress in Medical Physics
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• v.21 no.1
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• pp.70-77
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• 2010

This study tested how S/N (Signal to Noise Ratio) ratios and ADC (apparent diffusion coefficient) values vary with different T-scores in a group of patients with osteoporosis. Based on DEXA (Dual Energy X-ray Absorptiometry) T-scores for L1.L4 for two groups of subjects consisting of 30 healthy people without osteoporosis and 30 patients who came for treatment of waist (lumbar or low back) pain and were suspected to have osteoporosis as judged from the simple X-ray findings, this study classified every spine into two groups of osteoporosis and osteopenia. Signal intensity measurements were made in the four regions of L1 to L4 on diffusion-weighted MR images obtained using 1.5T MR scanner, while ADC measurements were obtained from ADC map images. As an approach for quantitative analysis, the comparison of the variances in S/N ratios and ADC values for varying T-scores in the selected regions of interest was carried out based on averaged T-scores, S/N ratios, and ADC values. Also, the variances in S/N ratios and ADC values for each of the groups of osteoporosis and osteopenia, which were classified into by T-scores, were compared. For qualitative analysis, a careful naked eye examination of signal intensity differences in the area of L4 was made on T1-weighted sagittal images for each of the healthy (normal), osteopenia, and osteoporosis groups. In the qualitative analysis, it was found that for both the osteopenia group and the osteoporosis group, as T-scores deceased, the S/N ratios on diffusion-weighted MR images also decreased, with the greatest decrease in the S/N ratio found in the osteoporosis group. Additionally, among the three groups, the lowest S/N ratio was found in the osteoporosis group. With respect to ADC map, it was found that for both the osteopenia group and the osteoporosis group, as T-scores deceased, the ADC values on diffusion-weighted MR images also decreased, with the greatest decrease in the ADC values found in the osteoporosis group. Additionally, among the three groups, the lowest ADC value was found in the osteoporosis group. On the other hand, in the qualitative analysis, the osteoporosis group showed the highest signal intensity. Additionally, among the three groups, the lowest signal intensity was found in the healthy (normal) group. It was found that as osteoporosis progressed, S/N ratio and ADC decreased, whereas signal intensity increased on T1-weighted images. Also, in diagnosing osteoporosis, MRI tests turned out to be (more) effective.

• Journal of Bio-Environment Control
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• v.12 no.4
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• pp.240-244
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• 2003

The purpose of this study was to investigate a proper $Ca^{2+}\;:\;K^+$ ratio in nutrient solution to produce marjoram and oregano by hydroponics. Two herbs were grown for 40 days with the $Ca^{2+}\;:\;K^+$ ratio of 3.5;13, 4.5:11(standard herb's nutrient solution), 5.5:9 and 6.5:7mM${\cdot}L^{-1}$ of herb's nutrient solution developed by European Vegetable R &D Center, Belgium. The ratio of 5.5:9, and 6.5:7 mM${\cdot}L^{-1}$ showed better results in growth of marjoram than other treatments. Vitamin C contents and amounts of esential oil were the highest in the ratio of 5.5:9 and 6.5:7, respectively. Inoregano, the growth and vitamin C contents were the highest in the ratio of 5.5:9 and 6.5:7 mM${\cdot}L^{-1}$, respectively. The content (%) and amount (mg/plant) of essential oil were the highest in the ratio of 6.5:7mM${\cdot}L^{-1}$. These results indicated that 5.5:9 and 6.5:7 mM${\cdot}L^{-1}$were proper $Ca^{2+}\;:\;K^+$ ratio of nutrient solution of marjoram and oregano, respectively, by hydropoinics.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3B
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• pp.153-159
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• 2012

In this study, we proposed modified settling basins transformed by substituting the downstream sill for low head weirs such as generic labyrinth weir and inclined crest labyrinth weir worked as internal baffles. Laboratory experiments were carried out to understand hydraulic characteristics inside of the settling basin to improve the efficiency of sedimentation rate. For a quantitative analysis, we suggested the headwater ratio($H_t/P$), the magnification ratio(L/W) and the inflow rate per total crest length($q_L$) as primary analysis indexes for sedimentation efficiency. Six different types of settling basin were used for labscaled pilot tests by distinguishing with internal structures. Based on results, the variation of headwater ratio with the change of magnification ratio would highly affect the deposition efficiency(%) and it was improved under specific condition that repeating arrange number(N) of labyrinth weir was between 2 and 4. Also, the regression analysis showed that initial condition and shape for improving sedimentation efficiency were plotted on the graph for both $q_L{\geq}3.5cm^2/s$ and $L/W{\leq}3.5$. It would be expected that the geometrically optimized labyrinth settling basin could be designed with proper deposition efficiency for inflow rates of influent and required area of settling basin utilizing the proposed analysis index in this study.