• Imaging Science in Dentistry
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• v.30 no.1
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• pp.71-79
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• 2000

Purpose : This study was aimed to evaluate the cell cycle arrest and apoptosis induction after irradiation and epidermal growth factor (EGF) treatment in three human epithelial tumor cell lines (A431, Siha, KB). Materials and Methods: Single irradiation of 2, 5 and 10 Gy was done on three cell lines with 5.38 Gy/min dose rate using Cs-137 irradiator at room temperature. Also, EGF of 10 ng/ml was added immediately after 10 Gy irradiation. Cell growth was evaluated by counting the living cell number using a hemocytometer at 1 day, 2 days, 3 days, 4 days and 5 days after irradiation. Cell cycle arrest and apoptosis induction were assayed with the flow cytometry at 8 hours, 12 hours, 1 day, 2 days, 3 days, 4 days and 5 days after irradiation. Results : Growth of irradiated three cell lines were inhibited in proportion to radiation dose. EGF treatment after irradiation showed various results according to cell lines. On all cell lines, G2 arrest was detected after 8 hours and maximized after 12 hours or 1 day. Amount of G2 arrest was positively dose dependent. However, EGF showed no significant change on G2 arrest. G2 arrest was recovered with time at 2 Gy and 5 Gy irradiation. However, at 10 Gy irradiation, G2 arrest was continued. Apoptosis was detected at 10 Gy irradiation. On EGF treated group after irradiation, A431 and Siha cell lines showed slightly increased apoptosis but there was no statistically significant difference. KB cell line showed no marked change of apoptosis induction. Conclusion : Irradiation effects on cell cycle arrest and apoptosis induction in three human epithelial tumor cell lines, however epidermal growth factor doesn't effect on.

• Imaging Science in Dentistry
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• v.49 no.4
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• pp.273-279
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• 2019

Purpose: This study was performed to investigate the effects of energy level, reconstruction kernel, and tube rotation time on Hounsfield unit (HU) values of hydroxyapatite (HA) in virtual monochromatic images (VMIs) obtained with dual-energy computed tomography (DECT)(Siemens Healthineers, Erlangen, Germany). Materials and Methods: A bone density calibration phantom with 3 HA inserts of different densities(CTWATER^®; 0, 100, and 200 mg of HA/㎤) was scanned using a twin-beam DECT scanner at 120 kVp with tube rotation times of 0.5 and 1.0 seconds. The VMIs were reconstructed by changing the energy level (with options of 40 keV, 70 keV, and 140 keV). In order to investigate the impact of the reconstruction kernel, virtual monochromatic images were reconstructed after changing the kernel from body regular 40 (Br40) to head regular 40 (Hr40) in the reconstruction phase. The mean HU value was measured by placing a circular region of interests (ROIs) in the middle of each insert obtained from the VMIs. The HU values were compared with regard to energy level, reconstruction kernel, and tube rotation time. Results: Hydroxyapatite density was strongly correlated with HU values(correlation coefficient=0.678, P<0.05). For the HA 100 and 200 inserts, HU decreased significantly at increased energy levels(correlation coefficient= -0.538, P<0.05) but increased by 70 HU when using Hr40 rather than Br40 (correlation coefficient=0.158, P<0.05). The tube rotation time did not significantly affect the HU(P>0.05). Conclusion: The HU values of hydroxyapatite were strongly correlated with hydroxyapatite density and energy level in VMIs obtained with DECT.

• Journal of Periodontal and Implant Science
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• v.46 no.2
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• pp.116-127
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• 2016

Purpose: The objective of this study was to investigate the relationships between primary implant stability as measured by impact response frequency and the structural parameters of trabecular bone using cone-beam computed tomography(CBCT), excluding the effect of cortical bone thickness. Methods: We measured the impact response of a dental implant placed into swine bone specimens composed of only trabecular bone without the cortical bone layer using an inductive sensor. The peak frequency of the impact response spectrum was determined as an implant stability criterion (SPF). The 3D microstructural parameters were calculated from CT images of the bone specimens obtained using both micro-CT and CBCT. Results: SPF had significant positive correlations with trabecular bone structural parameters (BV/TV, BV, BS, BSD, Tb.Th, Tb.N, FD, and BS/BV) (P<0.01) while SPF demonstrated significant negative correlations with other microstructural parameters (Tb.Sp, Tb.Pf, and SMI) using micro-CT and CBCT (P<0.01). Conclusions: There was an increase in implant stability prediction by combining BV/TV and SMI in the stepwise forward regression analysis. Bone with high volume density and low surface density shows high implant stability. Well-connected thick bone with small marrow spaces also shows high implant stability. The combination of bone density and architectural parameters measured using CBCT can predict the implant stability more accurately than the density alone in clinical diagnoses.

• Journal of Environmental Health Sciences
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• v.39 no.3
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• pp.211-222
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• 2013

Objectives: A great number of people visit forests for their bountiful healing factors. We investigated the quantity of terpene and analyzed the correlations with meteorological and environmental factors at Mt. Mudeung in order to support public health. Methods: The terpene amounts were investigated along 11 main trails using stainless steel tube packed by Tenax TA (150 mg) and Carbopack B (130 mg) during March to November 2012. Terpene amounts of 20 species (${\alpha}$-pinene, camphene, etc.), and meteorological and environmental factors were investigated in the field. Results: Terpene of 16 species was released from the forest and total terpene amounts were 2,080 pptv at the site of Chamaecyparis obtusa, the highest among 11 sites, nearby the first reservoir on Mt. Mudeung. Terpene concentrations in the forest were nine to 23 times higher than found in urban areas. Total terpene amounts had positive correlations with temperature, humidity, carbon dioxide and oxygen (p<0.01) with $R^2$ of 0.345, 0.369, 0.591, 0.145, respectively, from April to July. Wind speed and solar radiation in the forest had a negative correlation with terpene amounts and showed statistical insignificance with p-values of 0.118 and 0.233, respectively. Conclusions: This study suggests that the amounts of terpene around Mt. Mudeung are indeed higher, so visitors may enjoy a therapeutic walk in the forest with a healing effect. These results showed the forest was very effective for improving human health.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.9
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• pp.1391-1398
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• 2010

Red ginseng marc (RGM) was fermented by the solid-state fermentation using Bacillus subtilis HA to produce biologically active compounds. The red ginseng marc fermented without mugwort possessed higher mucilage content (11.5%) and proteolytic activity (277.5 unit/g). The RGM fermented with 3% mugwort showed lower production of mucilage and protease activity whereas higher tyrosine content (581.3 mg%) and consistency index ($8.8\;Pa{\cdot}s^n$). The mucilage produced from fermented RGM contained $\gamma$-PGA with 1,100 kDa of molecular weight, and its yield was 15.9 g/kg. 70% ethanol extract from the RGM fermented with 3% mugwort had the highest DPPH radical scavenging effect ($IC_{50}$ value of 0.57 mg/mL), and the water extract showed the highest ABTS radical scavenging effect, indicating $IC_{50}$ value of 1.24 mg/mL. Overall, the RGM fermented by B. subtilis HA with mugwort contained various biologically active compounds having antioxidant effects.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.6
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• pp.872-879
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• 2010

Textured vegetable protein (TVP) was fermented by the solid-state fermentation using Bacillus subtilis HA and biologically active compounds were produced by fermentation for 7 days. The longer fermentation time resulted in the color change of fermented TVP with strong dark red and yellow color. Melanoidin production rapidly increased until fermentation for 48 hr, but did change afterwards. The 70% ethanol extract of TVP fermented for 24 hr showed higher DPPH radical scavenging effect with $IC_{50}$ of 0.99 mg/mL but longer fermentation did not increase its activity. Also, 70% ethanol extract of TVP fermented for 72 hr indicated higher ABTS radical scavenging effect with $IC_{50}$ of 1.68 mg/mL. Consistency index in TVP fermented for 48 hr was the highest values with 7.89 $Pa{\cdot}s^n$. Viscoelastic properties of TVP fermented for 48 hr were maximally enhanced, and viscous value (G") is higher than the elastic value (G'). The $\gamma$-polyglutamic acid (PGA) content was increased by increasing fermentation time with 37.72% of $\gamma$-PGA at 168 hr. However, levan content and molecular weight of PGA were decreased with increasing fermentation time from 7.83% to 3.91% and 1649.3 kDa to 1286.8 kDa, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.6
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• pp.864-871
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• 2010

White and black garlic pastes were fermented by Leuconostoc mesenteroides and evaluated for its rheological and functional properties such as consistency, antioxidant and angiotensin converting enzyme inhibitory activity. The pH, acidity and solid content of black garlic paste were 4.60, 1.23%, 22.63%, respectively. The viable cell counts and consistency of fermented garlic was decreased by adding higher amounts of black garlic paste. Fermentation of white garlic (40%)/black garlic (10%) showed viable cell counts of $1.6\times10^{11}$, fluid consistency of 9.31 $Pa{\cdot}s^n$. Water and 70% ethanol extract from fermented garlic showed the polyphenol content of 6.29mg/mL and 5.99 mg/mL, respectively. Also, water extract indicated the DPPH radical scavenging effects and angiotensin converting enzyme (ACE) inhibitory activity with $IC_{50}$ 1.03 mg/mL and $IC_{50}$ 68.54 mg/mL, respectively. ACE inhibitory activity was increased with adding black garlic paste. Conversion of sucrose into dextran polymer in fermented garlic was drastically decreased by the addition of black garlic paste, indicating from 85% (0% black garlic) to 20% (20% black garlic) conversion yield. Garlic paste fermented with 10% black/40% white garlic showed the decrease in consistency and viable cell counts during both cold and freezing storages. In particular, consistency of fermented garlic was lower during freezing storage than cold storage, and the viable cell counts was drastically decreased after storage for 2 weeks.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.2
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• pp.86-97
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• 2005

Accurate estimation of the wave-induced pore water pressure in the seabed is key factor in studying the stability of the seabed in the vicinity of coastal structure. Most of the existing numerical models for wave structure seabed interaction have been linked through applying hybrid numerical technique which is analysis method separating the wave field and seabed regime. Therefore, it is necessary to develope a numerical model f3r simulating accurately wave$\cdot$structure$\cdot$ seabed interaction under wave loadings by the single domain approach for wave field and seabed regime together. In this study, direct numerical simulation is newly proposed. In this model, modeled fluid drag has been used to detect the hydraulic properties according to the varied geometrical shape inside the porous media by considering the turbulence resistance as well as laminar resistance. Contrary to hybrid numerical technique, direct numerical simulation avoids the explicit formulation of the boundary conditions at the fluid/porous media interface. A good agreement has been obtained by the comparison between existed experimental results by hydraulic model test and direct numerical simulation results far wave $\cdot$structure$\cdot$seabed interaction. Therefore, the newly proposed numerical model is a powerful tool for estimating the nonlinear dynamic responses among a structure, its seabed foundation and water waves.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.4
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• pp.401-412
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• 2008

Simulations of three-dimensional numerical wave tank are performed to investigate wave force acting on a large cylindrical structure and consequent wave deformation, which are induced by bore after breaking waves. The numerical model is based on the three-dimensional Navier-Stokes equations with a finite-difference method combined with a volume of fluid(VOF) method, which is capable of tracking the complex free surface, including wave breaking. In order to promote wave breaking of the incident wave, the approach slope was built seaward of the structure with a constant slope and a large cylindrical structure was installed on a flat bed. The incident waves were broken on the approach slope or flat bed by its wave height. In the present study, all waves acting on the large cylindrical structure were limited to breaking bore after wave breaking. The effects of the position of the structure and the incident wave height on the wave force and wave transformations were mainly investigated with the concern of wave breaking. Further, the relations between the variation of wave energy by wave propagation after wave breaking and wave force acting on the structure were discussed to give the understanding of the full-linear wave-structure interactions in three-dimensional wave fields.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.3
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• pp.180-201
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• 2020

It has been widely known that the effect of diffracted waves at the tip of composite breakwater with finite length causes the change of standing wave height along the length of breakwater, the spatial change of wave pressure on caisson, and the occurrence of meandering damage on the different sliding distance in sequence. It is hard to deal with the spatial change of wave force on trunk of breakwater through the two-dimensional experiment and/or numerical analysis. In this study, two and three-dimensional numerical techniques with olaFlow model are used to approach the spatial change of wave force including the impulsive breaking wave pressure applied to trunk of breakwater, the effect of rear region, and the occurrence of diffracted waves at the tip of caisson located on the high crested rubble mound. In addition, it is thoroughly studied the mean wave height, mean horizontal velocity, and mean turbulent kinetic energy through the numerical analysis. In conclusion, it is confirmed that the larger wave pressure occurs at the front wall of caisson around the still water level than the original design conditions when it generates the shock-crushing wave pressure checked by not two-dimensional analysis, but three-dimensional analysis through the change of wave pressure applied to the caisson along the length of breakwater.