• Kyungpook Mathematical Journal
• /
• v.59 no.1
• /
• pp.73-82
• /
• 2019

In this work, we give necessary and sufficient conditions under which every solution of a class of first-order neutral differential equations of the form $$(x(t)+p(t)x({\tau}(t)))^{\prime}+q(t)Hx({\sigma}(t)))=0$$ either oscillates or converges to zero as $t{\rightarrow}{\infty}$ for various ranges of the neutral coefficient p. Our main tools are the Knaster-Tarski fixed point theorem and the Banach's contraction mapping principle.

• Journal of the Korean Physical Society
• /
• v.73 no.10
• /
• pp.1546-1549
• /
• 2018

We have investigated core-levels of ZnO thin films at the interface with the graphene on Cu foil using in-situ X-ray Photoelectron Spectroscopy (XPS). Spectral evolution of C 1s, Zn 2p, and O 1s are observed in real time during RF sputtering deposition. We found binding energy (BE) shifts of Zn 2p and 'Zn-O' state of O 1s depending on ZnO film thickness. Core-levels BE shifts of ZnO will be discussed on the basis of electron transfer at the interface and it may have an important role in the electronic transport property of the ZnO/graphene-based electronic device.

• Journal of the Korean Physical Society
• /
• v.73 no.10
• /
• pp.1431-1436
• /
• 2018

We study the scaling of the price fluctuation in the Korean housing market. From the numerical analysis, we show that the normalized return distribution of the housing price, P(r), has a fat-tail and is well approximated by a power-law, $P(r){\sim}r^{-({\alpha}+1)}$, with ${\alpha}{\simeq}3$ for the whole data set. However, if we divide the data into groups based on the trading patterns, then the value of ${\alpha}$ for positive tail and negative tail can be different depending on the trading patterns. We also find that the autocorrelation function of the housing price decays much slower than that of the stock exchange markets, which shows a unique feature of the housing market distinguished from the other financial systems.

• Journal of the Korean Physical Society
• /
• v.73 no.12
• /
• pp.1867-1872
• /
• 2018

This study proposes a route for surface modification for p-type cobalt oxide-based gas sensors. We deposit a thin layer of Ni on the Co oxide film by sputtering process and annealed at $350^{\circ}C$ for 15 min in air, which changes a typical sputtered film surface into one interlaced with a high density of hemispherical nanoparticles. Our in-depth materials characterization using transmission electron microscopy discloses that the microstructure evolution is the result of an extensive inter-diffusion of Co and Ni, and that the nanoparticles are nickel oxide dissolving some Co. Sensor performance measurement unfolds that the surface modification results in a significant sensitivity enhancement, nearly 200% increase for toluene (at $250^{\circ}C$) and CO (at $200^{\circ}C$) gases in comparison with the undoped samples.

• The Korean Journal of Nuclear Medicine
• /
• v.32 no.4
• /
• pp.332-343
• /
• 1998

Purpose: The purpose of this study was to assess the diagnostic accuracy of various quantitation methods using F-18-fluorodeoxyglucose (FDG) in patients with malignant or benign lung lesion. Materials and Methods: 22 patients (13 malignant including 5 bronchoalverolar cell cancer; 9 benign lesions including 1 hamartoma and 8 active inflammation) were studied after overnight fasting. We performed dynamic PET imaging for 56 min after injection of 370 MBq (10 mCi) of FDG. Standardized uptake values normalized to patient's body weight and plasma glucose concentration (SUVglu) were calculated. The uptake rate constant of FDG and glucose metabolic rate were quantified using Patlak graphical analysis (Kpat and MRpat), three compartment-five parameter model (K5p, MR5p), and six parameter model taking into account heterogeneity of tumor tissue (K6p, MR6p). Areas under receiver operating characteristic curves (ROC) were calculated for each method. Results: There was no significant difference of rate constant or glucose metabolic rate measured by various quantitation methods between malignant and benign lesions. The area under ROC curve were 0.73 for SUVglu, 0.66 for Kpat, 0.77 for MRpat, 0.71 for K5p, 0.73 for MR5p, 0.70 for K6p, and 0.78 for MR6p. No significant difference of area under the ROC curve between these methods was observed except the area between Kpat vs. MRpat (p<0.05). Conclusion: Quantitative methods did not improve diagnostic accuracy in comparison with nonkinetic methods. However, the clinical utility of these methods needs to be evaluated further in patients with low pretest likelihood of active inflammation or bronchoalveolar cell carcinoma.

• Preventive Nutrition and Food Science
• /
• v.20 no.1
• /
• pp.73-77
• /
• 2015

As an approach to search for chemopreventive agents, we tested p-coumaric acid, 3-methoxy-p-coumaric acid (ferulic acid), and 3,5-dimethoxy-p-coumaric acid (sinapic acid) in B16/F10 melanoma cells. Intracellular melanin contents were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and cytotoxicity of the compounds were examined by lactate dehydrogenase (LDH) release. p-Coumaric acid showed inhibitory effect on melanogenesis, but ferulic acid increased melanin content, and sinapic acid had almost no effect on melanogenesis. Treatment with ferulic acid resulted in a 2 to 3 fold elevation in the production of melanin. Correlatively, cell viability decreased in a dose-dependent manner when treated with ferulic acid. However, ferulic acid did not affect the LDH release from the cells. Treatment with sinapic acid resulted in a 50~60% elevation in the release of LDH when treated with a $200{\mu}g/mL$ concentration and showed neither cytostasis nor increase of melanin synthesis in a dose-dependent manner. Taken together, p-coumaric acid inhibits melanogenesis, ferulic acid induces melanogenesis, and sinapic acid exerts cytotoxic effects in B16/F10 murine melanoma cells. The results indicate that the addition of methoxy groups to p-coumaric acid shows the melanogenic or cytotoxic effects in melanoma cells compared to the original compound. Therefore, this study suggests the possibility that methoxylated p-coumaric acid, ferulic acid can be used as a chemopreventive agent.

• Applied Chemistry for Engineering
• /
• v.7 no.1
• /
• pp.18-25
• /
• 1996

Power input in stirred vessel is especially important in the design of mixers, as well as the evaluation of mixing processes. A type of baffles in mechanically agitated vessels and power employed are major factors that determine the stirring efficiency in a large scale, multi-step processes. In the present study, power input in the totally baffled agitated vesseles was compared systematically in connection with several previous studies and adequate power input correlation was found to be : $Np_{(pitch)}=({\theta}/90^{\circ})Np_{(90^{\circ})}$ Power number correlation was dependent upon the distance of among the impeller in the agitated vesseles, as follows : $$Np=7.09(n_p)^{0.7}(\frac{b_(double)}{d})(\frac{H}{D})^{0.18}$$, $${n_p}^{0.7}(\frac{b_{(double)}}d)$$<2 $$Np=8.73\{(n_p)^{0.7}(\frac{b_{(double)}}{d})\}^{0.7}(\frac{H}{D})^{0.18}$$, $${n_p}^{0.7}(\frac{b_{(double)}}d)$$>2.

• Asian Pacific Journal of Cancer Prevention
• /
• v.17 no.12
• /
• pp.5247-5250
• /
• 2016

Objective: Endometriosis, one of the most common estrogen dependent gynecological disorders, can present as both benign and malignant disease. The prevalence of tumoral transformation is 0.7-1.6% and the most common tumors are clear cell and endometrioid carcinomas. Unfortunately, the pathogenesis of transformation is unknown. For this purpose, we examined molecular alterations in ovarian endometriosis and endometriosis-associated tumors. Methods: Using the data bank of Alzahra hospital pathology department and paraffin blocks from appropriate cases were identified. Sections were cut and stained for 3 markers: estrogen receptor, P53 and bcl2. Correlations between findings were investigated. Results: Nineteen cases of endometriosis-associated tumor and 19 cases of endometriosis were identified. Staining for bcl2 was documented in 14 of 19 (73.7%) of endometriosis-associated tumor cases and also 7 of 19 (36.8%) endometriosis cases (P=0.02). Only 3 of the 19 (15.8%) endometriosis-associated tumors exhibited positive staining for estrogen receptors, compared with 14 of 19 (73.7%) endometriosis cases (P<0.001). Positive staining for P53 was noted in 5 of 19 (31.6%) endometriosis-associated ovarian tumor samples but was absent in endometriosis samples (0%), (P =0.008). Conclusions: Endometriosis-associated tumors appear to be associated with overexpression of bcl2 and P53 and reduced expression of Estrogen receptor. These finding may help to diagnose tumoral transformation with a background of endometriosis.

• Clinics in Shoulder and Elbow
• /
• v.19 no.2
• /
• pp.73-77
• /
• 2016

Background: The first purpose of this study is to compare the clinical and radiological outcomes of surgical treatment for displaced midshaft clavicle fracture (Robinson type 2B1 vs. 2B2) with 3.5-mm low profile clavicular locking compression plate. The second purpose is to evaluate the difference of the results depending on the presence of accompanying injuries. Methods: Forty-nine patients who underwent an operation for the fractures were reviewed retrospectively. Fracture patterns were classified according to group 2B1 and 2B2 using Robinson's classification. For radiological outcome, time to union after operation was evaluated and for clinical outcome, American Shoulder and Elbow Society (ASES) score, University of California in Los Angeles (UCLA) score, visual analogue scale (VAS), and range of motion (ROM) were evaluated from preoperative period to last follow-up period. Results: The mean time for union was not significantly different in the 2B1 group and 2B2 group (p=0.062). No statistically significant difference in ASES score, UCLA score, and VAS was observed between 2B1 and 2B2 (p=0.619, p=0.896, p=0.856, respectively). In ROM, significant higher mean forward flexion and abduction was observed in 2B2 (p=0.025, p=0.017, respectively) and there was no difference in external rotation and external rotation at shoulder $90^{\circ}$ abduction position (p=0.130, p=0.180, respectively). There was no significant difference in clinical outcomes according to the accompanying injuries. Conclusions: There was no difference in clinical and radiological outcome between Robinson 2B1 and 2B2 type fracture after the operation. Accompanying injuries may not affect the clinical result of displaced midshaft clavicle fractures.

• Journal of the East Asian Society of Dietary Life
• /
• v.9 no.2
• /
• pp.207-213
• /
• 1999

This study was carried out to get a industrial information about a possibility of IgY antibody production, antimicrobial activity and properties of IgY antibody in egg yolk. The residual antibody activities of IgY were 91.5% after heating for 30min at 6$0^{\circ}C$. At the same time. these activities, were 73.2% after heating 15min at $65^{\circ}C$ and decreased vapidly at 7$0^{\circ}C$ and little antibody activity was left after heating for 15min at 8$0^{\circ}C$. When the prepared IgY was incubated at various pH ranges from 7 to 2 for 5hr at 37$^{\circ}C$., the antibody activity was stable from pH 7 to 4 and remained to 69.8% at pH 3.