• Journal of the Korean Ceramic Society
• /
• v.30 no.7
• /
• pp.549-556
• /
• 1993

Interfacial shear strength plays an important role in determining the mechanical properties of a fiber-reinforced ceramic composites. In this study, the effect ofinterlayer thickness on mechanical properties of Nicalon-fiber-reinforced SiC composites fabricated via polymer solution infiltration/chemical vapor infiltration (PSI/CVI) was studied. It was found that the flexural strength and fracture toughness of the composites were increased with the interlayer thickness and showed maximum value at the interlayer thickness of 0.66${\mu}{\textrm}{m}$. Typical flexural strength and fracture toughness of Nicalon-fiber-reinforced SiC composites with interlayer thickness of 0.66${\mu}{\textrm}{m}$ were 391.7$\pm$34.6MPa and 15.1$\pm$1.8MPa.m1/2, respectively.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2000.02a
• /
• pp.157-157
• /
• 2000

The adsorption processes of methyl chloride on Si(100)-2$\times$1 have been studied by low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and semiempirical PM3 calculations. The dissociative adsorption of the methyl chloride on Si(100) takes place without breaking of the silicon dimer with high efficiency. For adsorption at the room temperature, the existence of a precursor state is confirmed by the behavior of the sticking probability depending on the coverage and temperature. From AES measurements, the determined activation barrier of adsorption ($\Delta$ Hads) is -28.4 kj/mol. This results indicate that the dissociative process is nonactivated. The optimized precursor state of CH3Cl on the Si(100)-2$\times$1 surface was determined by PM3 calculations based on a cluster model.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.4
• /
• pp.1589-1595
• /
• 2014

Objective: Forkhead box C2 (FOXC2) is a member of the winged helix/forkhead box (Fox) family of transcription factors. It has been suggested to regulate tumor vasculature, growth, invasion and metastasis, although it has not been studied in cervical cancer. Here, we analyzed FOXC2 expression in cervical tissues corresponding to different stages of cervical cancer development and examined its correlation with clinicopathological characteristics. In addition, we examined the effects of targeting FOXC2 on the biological behavior of human cervical cancer cells. Methods: The expression of FOXC2 in normal human cervix, CIN I-III and cervical cancer was examined by immunohistochemistry and compared among the three groups and between cervical cancers with different pathological subtypes. Endogenous expression of FOXC2 was transiently knocked down in human Hela and SiHa cervical cells by siRNA, and cell viability and migration were examined by scratch and CCK8 assays, respectively. Results: In normal cervical tissue the frequency of positive staining was 25% (10/40 cases), with a staining intensity (PI) of $0.297{\pm}0.520$, in CIN was 65% (26/40cases), with a PI of $3.00{\pm}3.29$, and in cancer was 91.8% (68/74 cases), with a PI of $5.568 {\pm}3.449$. The frequency was 100% in adenocarcinoma (5/5 cases) and 91.3% in SCCs (63/69 cases). The FOXC2 positive expression rate was 88.5% in patients with cervical SCC stage I and 100% in stage II, showing significant differences compared with normal cervix and CIN. With age, pathologic differentiation degree and tumor size, FOXC2 expression showed no significant variation. On transient transfection of Hela and SiHa cells, FOXC2-siRNA inhibition rates were 76.2% and 75.7%; CCK8 results showed reduced proliferation and relative migration (in Hela cells from $64.5{\pm}3.16$ to $49.5{\pm}9.24$ and in SiHa cells from $60.1{\pm}3.05$ to $44.3{\pm}3.98$) (P < 0.05). Conclusion: FOXC2 gene expression increases with malignancy, especially with blood vessel hyperplasia and invasion degree. Targeted silencing was associated with reduced cell proliferation as well as invasion potential.

• The Journal of Korean Society for Radiation Therapy
• /
• v.31 no.1
• /
• pp.67-74
• /
• 2019

Purpose: The purpose is to correct for position errors caused by long treatment times. By correcting the target motion that can occur during lung SBRT using IntraFraction CBCT. Methods and materials: We analyzed retrospectively the IFM data of 14 patients with two treatment arc in the treatment plan for lung cancer with stereotactic radiotherapy. An IntraFraction Motion was applied to the Arccheck phantom to acquire the Gamma index data. Results : IntraFraction Motion during the first treatment arc is in the left-right(LR), superiorinferior(SI), anterior-posterior(AP) directions were $0.16{\pm}0.05cm$, 0.72 cm(max error), $0.2{\pm}0.14cm$, 1.26 cm, $0.24{\pm}0.08cm$, 0.82 cm and rotational directions was $0.84{\pm}0.23^{\circ}$, $2.8^{\circ}$(pitch), $0.72{\pm}0.23^{\circ}$, $2.5^{\circ}$(yaw), $0.7{\pm}0.19^{\circ}$, $2^{\circ}$(roll). IntraFraction Motion during the second treatment arc is in the LR, SI, AP directions were $0.1{\pm}0.04cm$, 0.37 cm, $0.14{\pm}0.17cm$, 2 cm, $0.12{\pm}0.04cm$, 0.5 cm and rotational directions was $0.45{\pm}0.12^{\circ}$, $1.3^{\circ}$, $0.37{\pm}0.1^{\circ}$, $1^{\circ}$, $0.35{\pm}0.1^{\circ}$, $1.2^{\circ}$. Gamma index pass rates were $82.64{\pm}10.51%$, 48.4 %. Conclusions : In this study, we examined the validity of IntraFraction Motion correction in lung SBRT and the efficiency of IntraFraction CBCT. Due to the nature of SBRT treatment, IFM may increase due to the increased treatment time. It is believed that the increase in IFM with the increase in treatment time can be improved with the use of FFF Beam and additional position correction using CBCT during treatment.

• Analytical Science and Technology
• /
• v.14 no.4
• /
• pp.317-323
• /
• 2001

Dissolution procedures of Monsanto catalyst which has been used to produce acrylronitrile by ammoxidation of propylene have been studied. Optimum dissolution condition of the catalyst supported on silica was obtained by microwave digestion system with mixed of HCl, HF and $H_2O_2$. When a safety device was activated by increased pressure in microwave vessel, Bi, Fe, Mo, Sb and U were not volatilized even though silica was volatilized as $SiF_4$. Quantification results by this method were $SiO_2$ $50.5{\pm}0.4%$, $Sb_2O_3$ $29.6{\pm}0.6%$, $UO_2$ $10.2{\pm}0.1%$, $Fe_2O_3$ $6.1{\pm}0.1%$, $MoO_3$ $0.73{\pm}0.01%$ and $Bi_2O_3$ $0.49{\pm}0.01%$ by ICP-AES and the relative error was within ${\pm}10%$ except bismuth.

• Journal of the Korean Ceramic Society
• /
• v.29 no.5
• /
• pp.357-366
• /
• 1992

Residual organics were considered as impurity in Sol-Gel method. The purpose of this study was to find the conditions to contain as much residual organics as possible in silica gel prepared from TEOS(tetraethylortho-silicate) by Sol-Gel method. Residual organics are to be expected to have reduction effect on synthesizing Si3N4 from silica gel. The results of this study are follows: 1) The maximum content of entrapped carbon was 19.8 wt.%(C/SiO2=0.25 wt.ratio) in silica gel synthesized under the conditions 1.5 fold mole water for incomplete hydrolysis, 2.5 fold mole phenol as a solvent and 0.1 fold mole HCl as a catalyst to TEOS. 2) Silica gel with organics entrapped by Sol-Gel method had a positive effect on the formation of Si3N4 compared with commercial silica gel. 3) Sintered body of synthesized $\alpha$-Si3N4 with Y2O3 and Al2O3 as additives at 175$0^{\circ}C$ in N2 atmosphere showed bending strength, 602$\pm$20 MPa and frature toughness 4.45$\pm$0.15 MPa.m1/2.

• Proceedings of the KSME Conference
• /
• 2000.11b
• /
• pp.174-179
• /
• 2000

Ultrafine particles have been used widely in many high technology industrial areas. The spherical nonagglomerated and uniform nanometer-size $SiO_2$ particles are synthesized by the direct injection of TEOS(Tetraethyorthosilicate) using electro-hydrodynamic spray ins method. Electro-hydrodynamic spray can generate in the range of submicron-size TEOS particles with high electric charge by applying a high electric field between the liquid injection nozzle and the reaction tube. This TEOS particles are thermally decomposed or oxidized to produce nanometresized $SiO_2$ particles in the reaction tube. Spherical, nonagglomerated and ultrafine particle generated and examined at furnaced temperature, $800^{\circ}C$ and TEOS flowrate of 0.49 or $1.00cm^3/hr$ using SEM and SMPS. As the total gas flowrate changes from 1.51pm to 5.01pm, the mean diameter of $SiO_2$ particle decreases from 120 nm to 68nm.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.11
• /
• pp.1251-1256
• /
• 2015

In this paper, the processing conditions of the amorphous silicon film growth were investigated the effect in forming the HSG-Si on the surface of the storage electrode. As a result, when the amorphous silicon film phosphorus concentration is greater than $5.5{\pm}0.1E19atoms/cm^3$, HSG-Si is not formed correctly and showed the concentration dependency of HSG formation. Also, the optimum condition of the phosphorus concentration for amorphous silicon and HSG thickness are $4.5E19atoms/cm^3$ and $450{\AA}$, respectively, because of the HSG thickness over the $500{\AA}$ create to bit failure according to a short of the electrodes and the electrode.

• Journal of the Korean Chemical Society
• /
• v.26 no.5
• /
• pp.320-325
• /
• 1982

Utilyzing the solution prepared for the sulfur determination, the amounts of iron, copper and cobalt in the sulfide ore were determined by X-ray fluorescence spectrometry. The samples were dissolved with the mixed solutions of ,$Br_2\;and\;HNO_3$ and a major constituent of $SiO_2$was repelled from the solution by HF treatment several times. The analytical results agreed with the data obtained by conventional methods within ${\pm}$1.5% for Fe of the range of 20 to 50%, ${\pm}$1.0% for Cu of 10 to 15%, and ${\pm}$0.4% for Co of 1 to 5%. The present method was tolerably found to be reproducible.

• Journal of Environmental Impact Assessment
• /
• v.12 no.2
• /
• pp.99-108
• /
• 2003

We collected and analyzed PM10 samples to account for the characteristics of heavy metallic elements for yellow sand and non-yellow sand during springtime of 2002 at Busan, The mean PM10 mass concentration for springtime of 2002 was $219.82{\mu}g/m^3$ with the maximum $787.50{\mu}g/m^3$ and the minimum $19.44{\mu}g/m^3$. The mean concentration of metallic elements contained in PM10 are shown as follows : Si>Ca>Fe>Al>Na, respectively. The ratio of mean PM10 mass concentration for yellow sand($362.7{\mu}g/m^3$) to that for non-yellow sand($48.3{\mu}g/m^3$) was 7.5, the significant positive correlation (P<0.05) was found between yellow sand and non-yellow sand. The metallic elements concentration ratios of yellow sand to the non-yellow sand were over 10 times for Al, Ca, Mg, 4~8 times for Fe, Si, Mn. But the concentration of Na, Cu, Zn for non-yellow sand was higher than those of yellow sand. The crustal enrichment factor of Cd, Cu, Pb, Zn, Cr, K, Mn, Na, Ni for yellow sand was higher that of non-yellow sand over 10 times, and concentration rate of soil particles of yellow sand was increased 2.3 times that of nonyellow sand.