• Journal of Magnetics
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• v.20 no.4
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• pp.371-376
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• 2015

Magnetite nanoparticles were synthesized by adding excess ammonium hydroxide to a solution of iron (II) and (III) chlorides. The surfactants of oleic acid and Span 80 were applied in sequence to the magnetic particles as a combined stabilizer, and poly-${\alpha}$-olefin (PAO) 30 or 60 was used as the liquid base with a low or high viscosity, respectively. The ferrofluids were prepared with the concentrations of 200, 300, 400, and 500 mg/mL, and characterized by density, dispersion, magnetization, and viscosity. The density of the fluids increased proportionally to the concentration from 0.98 to 1.27 g/mL and 1.01 to 1.30 g/mL with PAO 30 base and PAO 60 base, and the dispersion stability was 77-95 and 81-74% for the PAO-30 and PAO-60-based fluids, respectively. The observed saturation magnetization values of the PAO-30 and PAO-60-based ferrofluids were 16 to 42 mT and 17 to 41 mT with the concentration increase in the range 200-500 mg/mL, respectively, depending upon the content of magnetic particles in the fluid. The viscosity variation of the PAO-30 and PAO-60-based ferrofluids in the temperature range $20-80^{\circ}C$ was the least with the concentrations of 400 and 300 mg/mL, respectively.

• Biomolecules & Therapeutics
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• v.18 no.1
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• pp.56-64
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• 2010

Pentoxifylline (PTX) has been used for the local reduction of fat tissue in the clinical setting. However, its safety and efficacy have not been proven. The aim of this study was to evaluate the effects of PTX on cell lines established from fat tissue. Newly cultured human preadipocytes and adipocytes from subcutaneous abdominal fat in addition to purchased human lung fibroblasts and keratinocytes were treated with PTX at different concentrations. Cell viability was determined using the Cell counting kit (CCK)-8 assay and lipolysis was evaluated using an Elisa kit. DNA fragmentation, Western blot analysis, Hoechst and Propidium Iodide (PI) staining and fluorescence activated cell scanning analysis were performed to confirm apoptosis. The viability of adipocytes, preadipocytes, keratinocytes and fibroblasts was markedly decreased at concentrations of PTX above 20 mM. Apoptosis was induced at concentrations of PTX over 40 mM in all cell lines. Lipolysis was increased by 60% at concentrations of PTX of 20 mM compared to the control. In conclusion, the results of this study showed that 20 mM of PTX induced lipolysis. At concentrations over 20 mM, PTX reduced the viability of all cells studied including: adipocytes, preadipocytes, fibroblasts and keratinocytes, in a non-specific manner.

• Journal of Environmental Impact Assessment
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• v.19 no.6
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• pp.527-537
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• 2010

This study are Geumjung mountain fortress of the Busan Metropolitan City in the north gate of the East gate around the trail to identify the vegetation structure importance value, dominance, species diversity, similarity index analysis. Results of the study, plot on the western slopes elevation 423-636m, slopes of $15{\sim}20^{\circ}$ slope areas, Pinus densiflora, Pinus thunbergii, Quercus acutissima, Pinus thunbergii, Pinus rigida, Carpinus coreana, Quercus mongolica are fulfilling a community. Trees layer a height 8~12m, coverage 40~70%, sub-trees layer the height 3~7m, coverage 10~80%, shrubs layer the height 0.8~1.5m, coverage 20-30%, herb layer the height 0.1~0.5m, coverage 5-10% were in the range of plot in the east slope elevation 452-647m, slopes in the slope of $5-30^{\circ}$ and Pinus rigida, Pinus thunbergii, Pinus densiflora, Quercus mongolica, Quercus dentata, Carpinus coreana is fulfilling a community. The trees layer height 8~13m, coverage 0~70%, sub-trees layer the height 2~6m, coverage 0~80%, shrubs layer the height 0.8~1.5m, coverage 20-40%, herb layer the height 0.1-0.5m, coverage 5-40% were in the range. The survey showed to be in relatively good vegetation, but in some areas of Pinus rigida, Quercus acutissima, as was predicted in succession, the shrub layer in the plot of some dominated vine plants and vegetation management will be needed for this purpose respectively.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.1282-1282
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• 2024

Given the widespread use of intelligent surveillance cameras at construction sites, recent studies have introduced vision-based deep learning approaches. These studies have focused on enhancing the performance of vision-based excavator activity recognition to automatically monitor productivity metrics such as activity time and work cycle. However, acquiring a large amount of training data, i.e., videos captured from actual construction sites, is necessary for developing a vision-based excavator activity recognition model. Yet, complexities of dynamic working environments and security concerns at construction sites pose limitations on obtaining such videos from various surveillance camera locations. Consequently, this leads to performance degradation in excavator activity recognition models, reducing the accuracy and efficiency of heavy equipment productivity analysis. To address these limitations, this study aimed to conduct sensitivity analysis of excavator activity recognition performance based on surveillance camera location, utilizing synthetic videos generated from a game-engine-based virtual environment (Unreal Engine). Various scenarios for surveillance camera placement were devised, considering horizontal distance (20m, 30m, and 50m), vertical height (3m, 6m, and 10m), and horizontal angle (0° for front view, 90° for side view, and 180° for backside view). Performance analysis employed a 3D ResNet-18 model with transfer learning, yielding approximately 90.6% accuracy. Main findings revealed that horizontal distance significantly impacted model performance. Overall accuracy decreased with increasing distance (76.8% for 20m, 60.6% for 30m, and 35.3% for 50m). Particularly, videos with a 20m horizontal distance (close distance) exhibited accuracy above 80% in most scenarios. Moreover, accuracy trends in scenarios varied with vertical height and horizontal angle. At 0° (front view), accuracy mostly decreased with increasing height, while accuracy increased at 90° (side view) with increasing height. In addition, limited feature extraction for excavator activity recognition was found at 180° (backside view) due to occlusion of the excavator's bucket and arm. Based on these results, future studies should focus on enhancing the performance of vision-based recognition models by determining optimal surveillance camera locations at construction sites, utilizing deep learning algorithms for video super resolution, and establishing large training datasets using synthetic videos generated from game-engine-based virtual environments.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.67-67
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• 2003

Tributyltin chloride (TBTCI) is an organotin compounds that have been widely used as antifouling agents and bioaccumulated in the food chain. TBTCI has been known to induce imposex in female gastropods. There are several reports that TBTCI increased testosterone level and inhibited the conversion of testosterone to estradiol by the aromatase cytochrome P450 enzyme. In this studies, we investigated the effects of TBTCI on steroidogenesis in testes, We dosed to 4-week-old Spragus-Dawleys (SD) male rats with TSTCI (0, 1, 5, 10, and 20mg/kg/day) daily by gavage for 14 days. TBTCI significantly decreased the weights of seminal vesicle, prostate, cowper's gland and LABC at 10 and 20mg/kg/day but significantly Increased the weights of liver at 10 and 20mg/kg/day and adrenals at 20mg/kg/day. mRNA levels of steroidogenic acute regulatory (StAR) and P450 aromatase were decreased and mRNA levels of cytochrome P450 17$\alpha$-hydroxylase/$C_{17-20}$ lyase (P450c17) were increased by TBTCI. TBTCI significantly increased serum testosterone level in dose-dependent manner. From above results, we found that TBTCI altered mRNA levels of enzymes related steroidogenesis, weights of organs and serum testosterone levels. This suggests that change of hormone levels may be due to alteration of mRNA levels of steroidogenic enzyme in testes, but further studies are necessary to investigate hormone levels in testis organ in order to find a relation of enzyme related to steroidogenesis with hormone levels. This work was supported by the Korea FDA Grant KFDA-03131-EDS-010.

• Journal of Life Science
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• v.18 no.3
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• pp.350-356
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• 2008

Biochemical characterization including hemagglutination of erythrocytes, molecular weight, optimum temperature, thermal stability, optimum pH, carbohydrate specificity, and inhibitory effect of metal ion were studied in lectin of eggplant (Solanum melongena L.) fruit prepared by ammonium sulfate fractionation and affinity chromatography. This lectin was agglutinated by trypsin-treated rat blood erythrocyte. The molecular weight of this lectin by SDS-PAGE was estimated to be approximately 19.3 kDa of a single band. This lectin has no activity by 7 carbohydrates containing D-glucose. The optimum range of temperature and pH were $10-20^{\circ}C$ and pH 6.2-7.2, respectively. This lectin was relatively stable at $20-70^{\circ}C$. And the activity of this lectin was not inhibited by $Ca^{2+},\;Co^{2+},\;Cu^{2+},\;Fe^{2+},\;Mg^{2+}$, and $Mn^{2+}$.

• Analytical Science and Technology
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• v.20 no.5
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• pp.419-423
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• 2007

Environmental low level tritium analysis was studied using liquid scintillation counter(LSC) and electrolytic enrichment method. To obtain low level blank count, various counting vials were investigated. Among them, teflon coated PE vial had a lower blank count rate (1.86 cpm) and we obtained 2.01 Bq/L detection and tritium separation factor was above 20. LSC counting efficiency obtained $28.70{\pm}0.27%$ using the NIST tritium standard water sample.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.3
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• pp.471-479
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• 2001

The purpose of this study was to compare the effect of the high intensity halogen light $(850\sim1000mW/cm^2)$ with that of the conventional halogen light $(400mW/cm^2)$ on the hardness of composite resin. Three resin composites (Z-100, 3M, U.S.A. : Tetric Ceram, Vivadent, Liechtenstein; SureFil, Dentsply, U.S.A.) were filed in the stainless steel moulds which were 4mm in diameter and 2, 3, 4, and 5mm in depth, respectively. They were cured under the four different modes : (1) conventional mode, 40 seconds at $400mW/cm^2$; (2) 'ramp' mode, 10 seconds at 100 to $1000mW/cm^2$ plus 10 seconds at $1000mW/cm^2$; (3) 'boost' mode, 10 seconds at $1000mW/cm^2$; and (4) 'standard' mode, 20 seconds at $850mW/cm^2$. The surface hardnesses of the top and the bottom of the resin samples were measured with a microhardness tester (MXT70, Matsuzawa, Japan). The top surface hardness was not significantly different among the curing modes. The bottom surface hardness was generally the highest in the conventional mode and the lowest in the high intensity boost mode. There was no significant difference in the bottom surface hardness between the conventional mode and the high intensity standard mode in 2mm depth. The results suggest that the curing time of the high intensity halogen light $(850mW/cm^2)$ should be at least 20 seconds to produce the equal level of the bottom surface hardness of 2mm resin composite as compared to the hardness produced by the conventional halogen light $(400mW/cm^2)$.

• Fire Science and Engineering
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• v.26 no.5
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• pp.67-72
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• 2012

Fire simulation was carried out for an enclosure with three doorways of $20{\times}10{\times}3m^3$ and a cleanroom of $44{\times}48{\times}10m^3$, to suggest appropriate grid size in fire simulations by using of FDS for large scale buildings. The variations of temperature and visibility with time were compared for the x and y direction grid sizes of 0.1~1.0 m (aspect ratios 0.5~5.0), fixing the z direction grid size 0.2 m. The results showed that the grid sizes 0.5 m (aspect ratio 2.5) or smaller are appropriate among the grid sizes tested, whereas 1.0 m is not acceptable. It was confirmed that estimate of the available safe egress time requires a great care due to fluctuations in temperature, visibility, etc., and further investigations on the grid size when selecting a large grid size inevitable, and on the aspect ratios for a larger grid are in need.

• Analytical Science and Technology
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• v.11 no.3
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• pp.213-221
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• 1998

The determination of inorganic anions by capillary zone electrophoresis is reported. A ten component synthetic mixture of anions of bromide, chloride, fluoride, nitrite, nitrate, sulfite, sulfate, perchlorate, chlorate and chlorite was separated by the capillary column and detected by indirect UV method. The running buffer contained 5 mM ammonium dichromate, 10 mM ammonium acetate, 20 mM diethylenetriamine, 10% methanol solution at pH 9.3. A potential of 15 kV at the cathode (reversed polarity) was utilized for the separation of inorganic anions. A complete separation of anions was achieved in less then 10 min and the applicabilities of the method for the analysis of real samples was demonstrated. We compare the concentration of anions in toluene inhaled humen's urine and in postmortem bloods obtained by capillary zone electrophoresis and ion chromatograph.