• Progress in Medical Physics
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• v.22 no.4
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• pp.190-197
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• 2011

Currently, the dose distribution calculation used by commercial treatment planning systems (TPSs) for high-dose rate (HDR) brachytherapy is derived from point and line source approximation method recommended by AAPM Task Group 43 (TG-43). However, the study of Monte Carlo (MC) simulation is required in order to assess the accuracy of dose calculation around three-dimensional Ir-192 source. In this study, geometry factor was calculated using segmented sources integration method by dividing microSelectron HDR Ir-192 source into smaller parts. The Monte Carlo code (MCNPX 2.5.0) was used to calculate the dose rate $\dot{D}(r,\theta)$ at a point ($r,\theta$) away from a HDR Ir-192 source in spherical water phantom with 30 cm diameter. Finally, anisotropy function and radial dose function were calculated from obtained results. The obtained geometry factor was compared with that calculated from line source approximation. Similarly, obtained anisotropy function and radial dose function were compared with those derived from MCPT results by Williamson. The geometry factor calculated from segmented sources integration method and line source approximation was within 0.2% for $r{\geq}0.5$ cm and 1.33% for r=0.1 cm, respectively. The relative-root mean square error (R-RMSE) of anisotropy function obtained by this study and Williamson was 2.33% for r=0.25 cm and within 1% for r>0.5 cm, respectively. The R-RMSE of radial dose function was 0.46% at radial distance from 0.1 to 14.0 cm. The geometry factor acquired from segmented sources integration method and line source approximation was in good agreement for $r{\geq}0.1$ cm. However, application of segmented sources integration method seems to be valid, since this method using three-dimensional Ir-192 source provides more realistic geometry factor. The anisotropy function and radial dose function estimated from MCNPX in this study and MCPT by Williamson are in good agreement within uncertainty of Monte Carlo codes except at radial distance of r=0.25 cm. It is expected that Monte Carlo code used in this study could be applied to other sources utilized for brachytherapy.

• Korean Journal of Environmental Biology
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• v.29 no.3
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• pp.126-137
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• 2011

Although Sumunmulbangdui wetland at the Halla Mountain in Jeju Island, a kind of montane wetlands, has been considered to bear high biodiversity, no study has been reported on the bacterial diversity. In this study, soil and water samples were collected from the wetland in order to isolate novel bacterial species. Bacterial strains belonging to the phyla Bacteroidetes, Firmicutes, and Actinobacteria were isolated after spreading soil and water samples onto solid agar media. The 16S rRNA gene sequences of the strains assigned to the three phyla were compared to those of type strains of the species in the phyla. The strains that showed less than 98.7% 16S rRNA gene sequence similarity to the validly published species were considered to be novel species candidates. A total of 32 strains were regarded as novel species candidates in the phyla Bacteroidetes, Firmicutes, and Actinobacteria. Diversity of novel species candidates was very low; the candidates were confined to only few genera. In the Bacteroidetes, 13 novel candidate species were affiliated with the genera Mucilaginibacter, Sphingobacterium, Pedobacter, Flavobacterium, and Chryseobacterium. A total of 13 novel candidate species that assigned to the genera Paenibacillus Lysinibacillus, and Bacillus were identified in the phylum Firmicutes. Only two candidate species that belonged to the genera Mycobacterium and Nocardia were excavated in the Actinobacteria. Cultural, physiological, and chemotaxonomic characteristics have been determined for the novel species candidates, and the characteristics are described in this study.

• Journal of Life Science
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• v.22 no.7
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• pp.889-896
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• 2012

Melanin synthesis is catalyzed by tyrosinase. To investigate the whitening effect of Hizikia fusiformis, fractions from ethanol extract of H. fusiformis were prepared by a systematic fractionation procedure with solvents such as methanol, hexane, butanol, and $H_2O$. The ethanol extract and its fractions were then subjected to evaluate the inhibitory effects on the tyrosinase activity and melanin synthesis in murine B16F10 melanoma cells. The ethanol extract and aqueous fraction exhibited a whitening effect with no cytotoxicity. The ethanol extract showed the highest whitening effect among the samples. The inhibitory effect of $100{\mu}g/ml$ of ethanol extract was higher than that of $10{\mu}g/ml$ of arbutin, but it was lower than that of $10{\mu}g/ml$ of kojic acid. Furthermore, the inhibitory effects of $100{\mu}g/ml$ of methanol, hexane, butanol, and aqueous fractions were similar to those of $10{\mu}g/ml$ of arbutin. The antioxidant activities were examined by comparing the results with that of ascorbic acid as a positive control. The ethanol extract and aqueous fraction showed relatively higher DPPH radical-scavenging activities compared with the other samples. Furthermore, $500{\mu}g/ml$ of ethanol extract and aqueous fraction diminished LPS-induced iNOS expression to 82 and 80%, respectively. These results suggest that ethanol extract and aqueous fraction of H. fusiformis could be used as cosmetic ingredients for whitening and skin protection effects.

• The korean journal of orthodontics
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• v.40 no.6
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• pp.421-431
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• 2010

Objective: This study aimed to verify the intra-individual reproducibility of the natural head position (NHP) in adult Korean patients in the centric relation (CR) position and to prove the inter-individual variability of the Frankfurt horizontal (FH) plane and sella-nasion (SN) line compared to the true horizontal line (THL). In addition, the study aimed to investigate the correlations between linear measurements from A-point and B-point to the nasion true vertical line (NTVL) and angular measurements from A-point and B-point to the SN line. Methods: Two lateral cephalograms were taken of 116 subjects (23 males, 93 females) with CR wax bites in a NHP at a one-week interval. Results: Method errors of three variables and intraclass correlation coefficients of six parameters proved the intra-individual reproducibility of NHP (p < 0.001). The angle of the FH to the THL was not significantly different from $0^{\circ}$ (p > 0.05), but it was clinically variable (SD $3.89^{\circ}$) on the inter-individual level. Conversely, the angle of the SN line to the THL was significantly different from $7^{\circ}$ (p < 0.05). Very low correlation was found between the linear measurements and angular measurements of A-point and B-point (p < 0.01). Conclusions: The NTVL could be a useful reference line for assessing the antero-posterior position of the maxilla and mandible of Korean adult patients in NHP and CR.

• Korean Journal of Environment and Ecology
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• v.31 no.6
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• pp.557-563
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• 2017

Gastrodia elata (Orchidaceae) is a perennial parasitic plant that has a unique lifestyle of being in a symbiotic interaction with fungi. The underground root of Gastrodia is used for medicinal treatment to cure high blood pressure, stroke, leukemia, headaches, and especially neurasthenia. This study is intended to investigate the effect of the global warming on the ecological responses of Gastrodia. We cultivated the small tuber of Gastrodia with the oak wood lot and mulberry fungus under control (ambient $CO_2$ concentration + ambient temperature, ACAT), temperature treatment (ambient $CO_2$ concentration+elevated temperature, ACET), and $CO_2$+temperature treatment (elevated $CO_2$ concentration+elevated temperature, ECET). The elevated $CO_2$ concentration was about twice in the ambient air while the elevated temperature was about $2^{\circ}C$ higher than the control group. And then we observed the growth and production of reproductive organs and the underground root. The observation showed that the number of flower stalk was highest at ACET and lowest at ECET. The flower stalk was longest at ACET and shortest at ECET. The inflorescence was longest at ACAT and shortest at ECET. The seed capsule was heaviest at ACET and lightest at ECET. The aboveground biomass was highest at ACET and lowest at ECET. The number of rhizomes was highest at ACET and lowest at ECET. The total rhizome biomass was highest at ACET and lowest at ECET. The average rhizome biomass was highest at ACET and lowest at ECET. The results showed that the growth of Gastrodia increased because of more active growth of Gastrodia elata when only the temperature increased and decreased when both $CO_2$ concentration and temperature increased, indicating the poor growth of Gastrodia elata under the global warming condition. Therefore, the Gastrodia elata plantation should be maintained at the temperature of $20-25^{\circ}C$ and not be exposed to a high $CO_2$ concentration.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.1
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• pp.74-85
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• 2016

For the assessment of seawater exchange rates in Danghangpo bay, Dangdong bay, Wonmun bay, Gohyunsung bay, and Masan bay, which are small-scale inner bays of Jinhae bay, an EFDC model was used to reproduce the seawater flow of the entire Jinhae bay, and Lagrange (particle tracking) and Euler (dye diffusion) model techniques were used to calculate the seawater exchange rates for each of the bays. The seawater exchange rate obtained using the particle tracking method was the highest, at 60.84%, in Danghangpo bay, and the lowest, at 30.50%, in Masan bay. The seawater exchange rate calculated based on the dye diffusion method was the highest, at 45.40%, in Danghangpo bay, and the lowest, at 34.65%, in Masan bay. The sweater exchange rate was found to be the highest in Danghangpo bay likely because of a high flow velocity owing to the narrow entrance of the bay; and in the case of particle tracking method, the morphological characteristics of the particles affected the results, since once the particles get out, it is difficult for them to get back in. Meanwhile, in the case of the Lagrange method, when the particles flow back in by the flood current after escaping the ebb current, they flow back in intact. However, when a dye flows back in after escaping the bay, it becomes diluted by the open sea water. Thus, the seawater exchange rate calculated based on the dye diffusion method turned out to be higher in general, and even if a comparison of the sweater exchange rates calculated through two methods was conducted under the same condition, the results were completely different. Thus, when assessing the seawater exchange rate, more reasonable results could be obtained by either combining the two methods or selecting a modeling technique after giving sufficiently consideration to the purpose of the study and the characteristics of the coastal area. Meanwhile, through a comparison of the degree of closure and seawater exchange rates calculated through Lagrange and Euler methods, it was found that the seawater exchange rate was higher for a higher degree of closure, regardless of the numerical model technique. Thus, it was deemed that the degree of closure would be inappropriate to be used as an index for the closeness of the bay, and some modifications as well as supplementary information would be necessary in this regard.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.1
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• pp.1-10
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• 2018

Recently, there has been rapid development in the field of flexible electronic devices, such as organic light emitting diodes (OLEDs), organic solar cells and flexible sensors. Encapsulation process is added to protect the flexible electronic devices from exposure to oxygen and moisture in the air. Using numerical simulation, we investigated the effects of the encapsulation layer on mechanical stability of the silicon chip, especially the fracture performance of center crack in multi-layer package for various loading condition. The multi-layer package is categorized in two type - a wide chip model in which the chip has a large width and encapsulation layer covers only the chip, and a narrow chip model in which the chip covers both the substrate and the chip with smaller width than the substrate. In the wide chip model where the external load acts directly on the chip, the encapsulation layer with high stiffness enhanced the crack resistance of the film chip as the thickness of the encapsulation layer increased regardless of loading conditions. In contrast, the encapsulation layer with high stiffness reduced the crack resistance of the film chip in the narrow chip model for the case of external tensile strain loading. This is because the external load is transferred to the chip through the encapsulation layer and the small load acts on the chip for the weak encapsulation layer in the narrow chip model. When the bending moment acts on the narrow model, thin encapsulation layer and thick encapsulation layer show the opposite results since the neutral axis is moving toward the chip with a crack and load acting on chip decreases consequently as the thickness of encapsulation layer increases. The present study is expected to provide practical design guidance to enhance the durability and fracture performance of the silicon chip in the multilayer package with encapsulation layer.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.3
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• pp.164-168
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• 2017

This study experimentally determined the effect of calcium ion ($Ca^{2+}$) (0-0.55 mM) and intial pH (4.0-10.0) on phosphorus (P) removal in synthetic wastewater (2 mg P/L) using titanium tetrachloride ($TiCl_4$) (0.12-0.18 mM). At TiCl4 concentration ([$TiCl_4$]) = 0.12 mM, the P removal efficiency was the highest (95.1%) at pH 7 but the efficiency decreased to 51.4% at pH 8. The P removal efficiency was 55.6% at $Ca^{2+}$ concentration ([$Ca^{2+}$]) = 0 mM but the efficiency increased to 90.5% at [$Ca^{2+}$] = 0.045 mM at [$TiCl_4$] = 0.12 mM. On the other hand, the P removal efficiency difference was not large (96.5-99.5%) with [$Ca^{2+}$] at [$TiCl_4$] = 0.15-0.18 mM. Within the design boundaries of $0.00{\leq}[Ca^{2+}]{\leq}0.18mM$ and $7.0{\leq}initial$ $pH{\leq}9.0$ at [$TiCl_4$] = 0.12 mM, the 90% P removal efficiency could be achieved at $[Ca2+]{\geq}0.10mM$ with pH 8.0 and $[Ca2+]{\geq}0.12mM$ with pH 9.0.

• The Korean Journal of Food And Nutrition
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• v.28 no.3
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• pp.369-375
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• 2015

This study was performed to investigate the physiological activities of Ginkgo biloba sarcotesta extracts before and after heat treatment. G. biloba sarcotesta was heated at $130^{\circ}C$ for 2 h and extracted with water, 70% ethanol and 80% methanol. ABTS and DPPH radical scavenging activities increased after heating in the water (14.95 mg AAE/g and 7.36 mg TE/g) and ethanol extracts (12.20 mg AAE/g and 6.23 mg TE/g). ${\alpha}$-Glucosidase inhibitory activity decreased after heating in all but the water extract. Angiotensin converting enzyme I inhibitory activities decreased after heating in all extracts. Nitric oxide production inhibitory activity increased from 12.40~44.55% of the raw sample to 40.76~72.39% of the heated sample at a concentration of $200{\mu}g/mL$. Lipid accumulation inhibitory activities were similar before and after heat treatment. The highest antiproliferative effects on MCF-7 human breast cancer cell lines were observed in 80% methanol extract in the heated sample. Cell viability at concentrations of 25, 50, 100, and $200{\mu}g/mL$ measured 34.88, 17.58, 8.44 and 10.48%, respectively. From the results, the antioxidant and antiproliferative activities of G. biloba sarcotesta extracts increased with heat treatment, and research on the identification of the structure for the active compounds are needed in further studies.

• Analytical Science and Technology
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• v.31 no.4
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• pp.149-160
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• 2018

A large number of functional living products are being produced for eco-friendly or health-promoting purposes. In the manufacturing process, such products could be adulterated with raw materials with high radioactivity, such as monazite and tourmaline. Thus, it is essential to manage raw materials and products closely related to the public living. For proper management, an accurate radioactivity data of the processed products are needed. Therefore, it is essential to develop a rapid and validated analytical method. In this study, the concentration of the radioactive $^{238}U$ and $^{232}Th$ in building materials (e.g., tile, cement, paint, wall paper, and gypsum board) and living products (e.g., health products, textiles, and minerals) were determined and compared by ED-XRF and ICP-MS. By comparing the results of both methods, we confirmed the applicability of the rapid screening and precise analysis of ED-XRF and ICP-MS. In addition, $^{238}U$ and $^{232}Th$ levels were relatively lower in building materials than in living products. Particularly, $^{232}Th$ content in 6 of 47 living products exceeded (maximum $8.2Bq{\cdot}g^{-1}$) the standard limit of $^{232}Th$ content in raw material ($1.0Bq{\cdot}g^{-1}$).