• Analytical Science and Technology
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• v.14 no.2
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• pp.159-166
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• 2001

A humic acid(HA, Aldrich Co) sample was subjected to ultrafiltration for molecular size fractionation and three fractions of different nominal size($F_1$: 1,000-10,000 daltons; $F_2$: 10,000-50,000 daltons; $F_3$: 100,000-300,000 daltons) were obtained. The structural characteristics of the size-fractionated HA were analyzed using their IR and solid state C-13 NMR spectral data, and the carboxylate group contents of the humic acids were determined using their pH titration data. The $^7F_0-{^5}D_0$ excitation spectra of Eu(III) complexes of the size-fractionated mgHA in aqueous solution were acquired($[Eu(III)]=1.0{\times}10^{-4}mol\;L^{-1}$, $(HA)=470-970mg\;L^{-1}$) at pH 5.0 using a pulsed tunable laser system, in which metal binding properties of the size-fractionated HA were elucidated and compared on another. Characterization of the IR and C-13 NMR spectral data indicated that the fraction($F_3$) with molecules of larger size were primarily aliphatic, while the fractions($F_1$, $F_2$) with smaller molecules of less than 50,000 daltons were predominantly aromatic. Titration data were consistent with an increase in the number of carboxylate groups per unit mass as molecular size became smaller. The $^7F_0-{^5}D_0$ excitation spectral data of Eu(III)-humate complexes showed that the peak maxima on these spectra were shifted toward lower energies with increasing molecular size of HA, indicating the higher degree of bindings of the Eu in the molecules of larger size. We also discussed the relationship of the lower energy shifts of the maximum peaks with increasing the molecular size of HA with the structural differences of the size-fractionated HA.

• Korean Journal of Environment and Ecology
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• v.22 no.5
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• pp.521-529
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• 2008

This research conducted a survey on waterbirds visiting this area four times by season from February to October in 2007 to look into the habitat use of waterbirds, to do a value and grade testing of the tidal flat by dividing the foreshore on Muan Bay located in Jeollanam-do into four areas (Dongam, Guro, Bokryong and Wangsan tidal flats). The survey results revealed that there existed a total of 15,755 individuals of 54 species including 2 species of grebes, 7 species of herons, 7 species of dabbling ducks, 6 species of diving ducks, 20 species of waders, 3 species of gulls and 9 other species and this survey also observed 9,291 individuals of the wading birds as a dominant group on Muan Bay. In these classified groups, the gulls and waders were observed to mostly use Dongam tidal flat as their habitat, while the group using Guro tidal flat as their habitat was mostly grebes, dabbling and diving ducks. As a result of UPGMA clustering analysis in consideration of the species and number of individuals, there appear the close similarities between Dongam and Bokryong tidal flats and so do Guro and Wangsan tidal flats. Taking a look at the grading of tidal flats by setting up ecological indexes, such as diversity index, abundance index, and dominance index, etc. legally reserved species and maximum number of individuals as a standard, the rank for the value and importance degree of Bokryong tidal flat appeared higher than that of the other three tidal flats. Like this, the gradation of tidal flats according to waterbirds are judged to able to suggest objective data on the issue of proper judgment and designation of valuable tidal flat areas and its subsequent effective preservation and management.

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.1
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• pp.13-21
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• 1985

This experiment was carried out to study the effect of the autumnal cutting times on the regrowth, the accumulated carbohydrate and dry matter yield of Italian ryegrass The results were summarized as follows: 1. In dry matter yield, the plot of earlier cutting was shown the highest yield (p<0.05), and that of the last-cutting was shown lower yield of dry matter than that the none-cutting plot. 2. TSC (Total Water Soluble Carbohydrate) content slightly decreased after the first cutting and gradually increased according to the regrowth, and then decreased again to the second cutting time. And also the TSC content levels of stubble, stem and leaf at one week before falling to sub-zero temperature were all the highest in the eariler cutting plot (p<0.01), and there was significant correlation between the TSC content level and the second harvested dry matter yield (p<0.05). 3. CGR (Crop Growth Rate) was decreased below $8^{\circ}C$. RLGR (Relative Leaf area Growth Rate) and NAR (Net Assimilation Rate) were both high during 30 days after regrowth, and low after regrowth in all plots. LAI (Leaf Area Index) rapidly increased during 50 days after cutting, and then slowly increased in all the plots, and maximum LAI was 3.4-5.8. Also dry matter yield increased in the plots having a high LAI to 70 days after cutting. 4. It was recognized that there were significant correlation between TSC, LAI, CGR, NAR, LWR (Leaf Weight Ratio) and the second harvested dry matter yield during the low temperature periods, and the degree of contribution to dry matter yield was in order of LWR>LAI>TSC>NAR>CGR.

• Journal of Biomedical Engineering Research
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• v.25 no.3
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• pp.171-182
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• 2004

This study investigates the biomechanical efficacies of vertebroplasty which is used to treat vertebral body fracture with bone cement augmentation for osteoporotic patients using image and finite element analysis. Simulated models were divided into two groups: (a) a vertebral body, (b) a functional spinal unit(FSU). For a vertebral body model, the maximum axial displacement was investigated under axial compression to evaluate the effect of structural integrity. The stiffness of each FE model simulated was normalized by the stiffness of intact model. In the case of FSU model, 3 types of compression fractures were formulated to assess the influence on spinal curvature changes. The FSU models were loaded under compressive pressure to calculate the change of spinal curvature. The results according to the various factors suggest that vertebroplasty has the biomechanical efficacy of the increment of structural reinforcement in a patient who has relatively high level of BMD and a patient with the amount of 15％, PMMA injection of the cancellous bone volume. The spinal curvatures after compression fracture simulation vary from 9$^{\circ}$ to 17$^{\circ}$ of kyphosis compared to that the spinal curvature of normal model was -2.8$^{\circ}$ of lordosis. These spinal curvature changes cause the severe spinal deformity under the same loading. As the degree of compressive fracture increases the spinal deformity also increases. The results indicate that vertebroplasty has the increasing effect of the structural integrity regardless of the amount of PMMA or BMD and the restoration of decreased vertebral body height may be an important factor when the compressive fracture caused the significant height loss of vertebral body.

• The korean journal of orthodontics
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• v.30 no.2 s.79
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• pp.127-142
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• 2000

This study have been carried out to find out the mechnical effect of Multiloop Edgewise Arch Wire(MEAW) making use of the finite element method. The tip back bend of MEAW taken in this analysis is $5^{\circ},\;10{\circ}\;and\;15{\circ}$. In addition, Class II or up & down elastic is applied to find out stress distribution and their values in PDL. A adult male of normal occlusion was selected to create the models of teeth and PDL. And the model of MEAW was also created using commercial finite element code (ANSYS version 5.2). The MEAW is forcibly engaged with a class II or up & down elastic, to determine the initial stress generated in PDL. Comparing the compressive and tensile stress at each reference-planes, following results are obtained. 1. When a MEAW of $5^{\circ},\;10{\circ}\;15{\circ}$ tip back bend was engaged with Class II or up & down elastic, the distribution of compressive, tensile stress in entire PDL is similar in each case. 2. The values of compressive and tensile stress in PDL is higher in $15{\circ}$ tip back bend case than in $10{\circ}\;or\;15{\circ}$ tip back bend case. 3. In the distal PDL of 1st and 2nd molar, compressive stress appears. The compressive area is more wide and its values is higher in PDL of 2nd molar than those in 1st molar. The compressive area and its values become more wide and higher according to the increase of the tip back bend. 4. The values of compressive stress are comparatively smaIIer in PDL of molars than those in premolars. 5. Comparing class II and up & down elastic case, tensile stress values in anterior teeth PDL are smaller md their distribution is more wide in up & down elastic case than class If elastic case. On another hand, there is no difference in distribution and stress values in PDL of posterior teeth between two cases. 6. Comparing the tensile area in PDL of anterior teeth, tensile stress values are maximum in PDL of canine.

• Korean Journal of Environmental Agriculture
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• v.16 no.2
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• pp.119-123
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• 1997

This study was performed to evaluate the influence of composting process with an intermittent aeration on the variation of rhizosphere soil temperature, $CO_2$ and $NH_3$ release, and the growth reponse of tomato plantlet in traditional and composting greenhouse. As the temperature of composting materials increased, rhizosphere soil temperature in 30cm depth rose up to $32^{\circ}C$ at one week after introduction. This was $18^{\circ}C$ higher than that of traditional greenhouse. After 20 days of active composting, temperature of rhizosphere soil started to decrease and remained constant at $23^{\circ}C$ after 35 days. For the traditional greenhouse, the averaged temperature ranged at $14{\sim}15^{\circ}C$. This results showed that composting greenhouse had the greater effect on increasing the underground temperature. Average value of evoluted $CO_2$ from the composting greenhouse for 70 days was $782{\sim}1154ppm$. This was $1.7{\sim}2.6$ times higher than that of the traditional greenhouse with an average of $440{\sim}462ppm$. $NH_3$ release was highest during $2{\sim}10$ days in intermittent aerated composting and reached to 134 ppm maximum on the 5th day, then decreased rapidly, and maintained at $3{\sim}4ppm$ after 17 days. Increased photosynthesis due to the $CO_2$ gas and a favorable rhizosphere environment due to the increased underground temperature resulted in improved growth, yield, and Brix degree of tomato fruit.

• The Korean Journal of Rheology
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• v.10 no.4
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• pp.234-246
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• 1998

The objective of this study is to investigate the correlation between steady shear flow (nonlinear behavior) and dynamic viscoelastic (linear behavior) properties for concentrated polymer solutions. Using both an Advanced Rheometic Expansion System(ARES) and a Rheometics Fluids Spectrometer (RFS II), the steady shear flow viscosity and the dynamic viscoelastic properties of concentrated poly(ethylene oxide)(PEO), polyisobutylene(PIB), and polyacrylamide(PAAm) solutions have been measured over a wide range of shear rates and angular frequencies. The validity of some previously proposed relationships was compared with experimentally measured data. In addition, the effect of solution concentration on the applicability of the Cox-Merz rule was examined by comparing the steady flow viscosity and the magnitude of the complex viscosity Finally, the applicability of the Cox-Merz rule was theoretically discussed by introducing a nonlinear strain measure. Main results obtained from this study can be summarized as follows : (1) Among the previously proposed relationships dealt with in this study, the Cox-Merz rule implying the equivalence between the steady flow viscosity and the magnitude of the complex viscosity has the best validity. (2) For polymer solutions with relatively lower concentration, the steady flow viscosity is higher than the complex viscosity. However, such a relation between the two viscosities is reversed for highly concentrated polymer solutions. (3) A nonlinear strain measure is decreased with increasing stran magnitude, after reaching the maximum value in small strain range. This behavior is different from the theoretical prediction demonstrating the shape of a damped oscillatory function. (4) The applicability of the Cox-Merz rule is influenced by the $\beta$ value, which indicates the slope of a nonlinear stain measure (namely, the degree of nonlinearity) at large shear deformations. The Cox-Merz rule shows better applicability as the $\beta$ value becomes smaller.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.1
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• pp.16-21
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• 2007

Purpose: We evaluated the diagnostic value of $^{18}F-FDG$ PET/CT (PET/CT) in lymph node staging of non-small cell lung cancer (NSCLC) considering calcification and histologic types as well as FDG uptake. Materials and Methods: Fifty-three patients (38 men, 15 women; mean age, 62 years) with NSCLC underwent surgical resection (tumor resection and lymph node dissection) after PET/CT. After surgery, we compared PET/CT results with the biopsy results, and analyzed lymph node metastases, based on histologic types. PET diagnosis of lymph node metastasis was determined by maximum SUV (maxSUV) > 3.0, and PET/CT diagnosis was determined by maxSUV > 3.0 without lymph node calcification. Results: By PET diagnosis, the sensitivity, specificity, and accuracy of overall lymph node staging were 45% (13 of 29), 91% (228 of 252), and 86% (241 of 281). Specificity was 91% in both squamous cell carcinoma and adenocarcinoma, while sensitivity was 71% in squamous cell carcinoma and 36% in adenocarcinoma. When we excluded calcified lymph node with maxSUV > 3.0 from metastasis by PET/CT diagnosis, specificity improved to 98% in squamous cell carcinoma and 97% in adenocarcinoma. The degree of improvement was not dependent on histologic types. Conclusion: PET/CT improved specificity of lymph node staging by reducing false positive lymph node regardless of histologic types of NSCLC.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.394-401
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• 2005

A nonthermal plasma-assisted fuel reformer was developed and the effects of operating variables on the performance of this reformer were studied. The $H_2$-rich reformed gas from the reformer was injected into a diesel engine under an idle condition and the effects of the amount of injected gas on the NO and soot reduction were investigated. It was found that with increasing electric power consumption, the degree of facility of ignition of the reforming reaction in the reformer could be enhanced. The performance of the reformer including $H_2$ concentration, $H_2$ recovery, and energy conversion was affected only by the O/C mole ratio. This was because the equilibrium reaction temperature was governed by the O/C mole ratio. With increasing O/C mole ratio, the $H_2$ recovery and energy conversion passed through the maximum values of 33.4% and 66%, respectively, at an O/C mole ratio between 1.2 and 1.5. The reason why the $H_2$ recovery and energy conversion increased with increasing O/C mole ratio when the O/C mole ratio was lower than $1.2{\sim}1.5$ appeared to be that the complete oxidation reaction occurred more enough with increasing O/C mole ratio in this low O/C mole ratio range and accordingly the reaction temperature increased. Whereas the reason why the $H_2$ recovery and energy conversion decreased with increasing O/C mole ratio when the O/C mole ratio was higher than $1.2{\sim}1.5$ appeared to be that the complete oxidation reaction was further advanced and the $H_2$ recovery and energy conversion decreased. As the weight ratio of reformed diesel to total diesel which entered the diesel engine was increased to $18.2{\sim}23.5%$, NO and soot reduction efficiencies increased and reached as values high as 68.5% and 23.5%, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.662-669
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• 2011

This study was conducted to biologically convert methane into methanol. Methane contained in biogas was bio-catalytically oxidized by methane monooxygenase (MMO) of methanotrophs, while methanol conversion was observed by inhibiting methanol dehydrogenase (MDH) using MDH activity inhibitors such as phosphate, NaCl, $NH_4Cl$, and EDTA. The degree of methane oxidation by methanotrophs was the most highly accomplished as 0.56 mmol for the condition at $35^{\circ}C$ and pH 7 under 0.4 (v/v%) of biogas ($CH_4$ 50%, $CO_2$ 50%) / Air ratio. By the inhibition of 40 mM of phosphate, 50 mM of NaCl, 40 mM of $NH_4Cl$ and $150{\mu}m$ of EDTA, methane oxidation rate could achieve more than 80% regardless of type of inhibitors. In the meantime, addition of 40 mM of phosphate, 100 mM of NaCl, 40 mM of $NH_4Cl$ and $50{\mu}m$ of EDTA each led to generating the highest amount of methanol, i.e, 0.71, 0.60, 0.66, and 0.66 mmol when 1.3, 0.67, 0.74, and 1.3 mmol of methane was each concurrently consumed. At that time, methanol conversion rate was 54.7, 89.9, 89.6, and 47.8% respectively, and maximum methanol production rate was $7.4{\mu}mol/mg{\cdot}h$. From this, it was decided that the methanol production could be maximized as 89.9% when MDH activity was specifically inhibited into the typical level of 35% for the inhibitor of concern.