• Corrosion Science and Technology
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• v.16 no.4
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• pp.175-182
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• 2017

Galvanic current measurement, polarization curves, electrochemical impedance spectroscopy and weight loss test were used to study the corrosion behavior of carbon steel before and after carbon fibers coupling to the carbon steel in simulated concrete pore solutions, and the film composition on the steel surface was analyzed using XPS method. The results indicate that passive film on steel surface had excellent protective property in pore solutions with different pH values (13.3, 12.5 and 11.6). After coupling with carbon fibers (the area ratio of carbon steel to carbon fiber was 12.31), charge transfer resistance $R_{ct}$ of the steel surface decreased and the $Fe^{3+}/Fe^{2+}$ value in passive film decreased. As a result, stability of the film decreased and the corrosion rate of steel increased. Decreasing of the area ratio of steel to carbon fiber from 12.3 to 6.15 resulted in the decrease in $R_{ct}$ and the increase in corrosion rate. Especially in the pore solution with pH 11.6, the coupling leads the carbon steel to corrode easily.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2983-2988
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• 2013

Second-order rate constants ($k_N$) have been measured spectrophotometrically for the reactions of 4-chloro-2-nitrophenyl X-substituted-benzoates (1a-1h) with a series of cyclic secondary amines in 80 mol % $H_2O$/20 mol % DMSO at $25.0{\pm}0.1^{\circ}C$. The Hammett plot for the reactions of 1a-1h with piperidine consists of two intersecting straight lines, while the Yukawa-Tsuno plot exhibits an excellent linear correlation with ${\rho}_X $ = 1.25 and r = 0.58, indicating that the nonlinear Hammett plot is not due to a change in the rate-determining step (RDS) but is caused by ground-state stabilization through resonance interactions for substrates possessing an electron-withdrawing group in the benzoyl moiety. The Br${\o}$nsted-type plot for the reactions of 4-chloro-2-nitrophenyl benzoate (1d) with a series of cyclic secondary amines curves downward with ${\beta}_2$ = 0.85, ${\beta}_1$ = 0.24, and $pK_a{^o}$ = 10.5, implying that a change in RDS occurs from the $k_2$ step to the $k_1$ process as the $pK_a$ of the conjugate acid of the amine exceeds 10.5. Dissection of $k_N$ into the microscopic rate constants $k_1$ and $k_2/k_{-1}$ ratio associated with the reaction of 1d reveals that $k_2$ is dependent on the amine basicity, which is contrary to generally held views.

• Journal of the Korean Magnetics Society
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• v.4 no.4
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• pp.335-339
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• 1994

The crystallograpic and magnetic properties of $Eu(Fe_{1-x}In_{x})O_{3}$ (x=0, 0.03과 0.05) have been studied by the methods of X-ray diffraction, $M\"{o}ssbauer$ spectroscopy, and magnetic hysteresis measurement at room temperature. The X-ray results show that the samples have a crystal structure of orthorhombic and unit cell volume of the crystal with the exception of the sample of x=0 increases as increasing the In concentration. In the analysis assuming two sets of six-line of $M\"{o}ssbauer$ spectra, it is found that the magnetic hyperfine field in each of sets decreases increasing x. The linewidth of the absorption lines for the samples increased as increasing x. This implies that the data involve a sum of several hyperfine patterns which have intensity being proportional to $_{n}P_{z}(x)$, the probability of an environment with z such Fe neighbors. The magnetic hysteresis curves show decrease of $M_{s}$ and increase of $H_{c}$ of the samples with increasing x.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.157-161
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• 2000

The Eye sensitivity in the difference conditions of a light source intensity consists of two functions by the receptor of cone and rod according to a wavelength. We derived a distribution function of $P({\lambda})=A{\cdot}e^{-({\lambda}-{\lambda}_0)^2/2W^2}$ using a respond probability of the receptor of cone-rod for a photon. It was well applied for a CIE eye's sensitivity curve of a wavelength, we obtained values in case of a relative sensitivity. A = 106.4, ${\lambda}_0=559.2$, W = 83.5 for a photopic and A = 99.3 ${\lambda}_0=502.6$, W = 79.5 for a scotopic, and in case of a sensitivity curve using 1m/W units. $A=7.2{\times}10^4$, ${\lambda}_0=559.2$, W = 83.5 for a photopic and $A=1.6{\times}10^5$, ${\lambda}_0=502.6$. W = 79.5 for a scotopic.

• Journal of Environmental Health Sciences
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• v.45 no.6
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• pp.594-604
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• 2019

Objectives: This study developed and validated an analysis method of urinary metals and metalloids that can be applied inductively with coupled plasma mass spectrometry (ICP-MS). Methods: 0.3 mL of urine was used to analyze 25 metal and metalloid compounds using ICP-MS. The validation of the analytical method included linearity, accuracy, precision, and the calculation of detection limits. In addition, a comparison test was performed with the graphite furnace atomic absorption spectrometry (GF-AAS) method, which is the current standard method, with urine samples of 66 healthy subjects. Results: The linearities (R²) of calibration curves of all 25 compounds were ≥ 0.999. Of the 25 compounds, the intra-day and inter-day accuracy% of 17 and 20 met ≤15%, respectively. In addition, fifteen compounds showed ≤15% recovery% for certificated reference materials. Intraclass correlation coefficients of the comparison between the current methods and new methods in this study were 0.952 (p-value<0.001) and 0.911 (p-value<0.001) for urinary cadmium and mercury, respectively. Conclusion: This study proposes an efficient simultaneous methodology that can analyze multi elements in smaller sample amounts. More reproduction experiments are needed in the future.

• Journal of Korean Medicine Rehabilitation
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• v.18 no.4
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• pp.13-24
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• 2008

Objectives : The purpose of this study was to investigate the effect of Poncirus Trifoliata(PT) on improvement of fecal impaction in spinal cord injured(SCI) rats. Methods : Fifteen adult Sprague-Dawley female rats were used weighing 200~250 g. A complete spinal cord transection was performed surgically at the T10 cord level. Experimental groups were assigned into 3 groups: Control(n=5), SCI+vehicle(n=5) and SCI+PT(n=5). PT was administered 100mg/kg in 0.5ml every 24 hours from 1st operation day to 7th day. We measured the body weight and food intake as well as the number and the weight of fecal pellet every morning. After 1 week of operation, whole colon was divided into proximal and distal segments under anesthesia. Each segment of colon was mounted with longitudinal direction in a organ bath. We measured spontaneous contraction and compared the area under the curve in each segments. Enhanced responses were observed by acetylcholine($10^{-6}M$), 40 mM KCl solution, L-NAME($10^{-4}M$). Results : The fecal number and weights were significantly higher in the group of SCI+PT than SCI+vehicle group(p<0.05). In organ bath study, area under the curves of the spontaneous contraction in SCI+vehicle and SCI+PT groups were significantly increased compared to control group. Contractility of distal colon in response to acetylcholine or KCl in SCI+vehicle group was significantly decreased compared to other groups(p<0.05). Conclusions : These results suggest that PT might be useful to promote bowel emptying in spinal cord injured rats.

• Journal of Gastric Cancer
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• v.4 no.2
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• pp.89-94
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• 2004

Purpose: There is no established treatment-related prognostic factor for gastric cancer except a curative tumor resection. This study was done to clarify the prognostic value of early postoperative intraperitoneal chemotherapy (EPIC) in patients with serosa-positive gastric cancer. Materials and Methods: We analyzed retrospectively the postoperative survival data of 209 patients with serosapositive gastric cancer treated by surgery and chemotherapy. The survival period for patients was calculated from the date of resection until cancer-related death or the last date of follow-up; Kaplan-Meier survival curves were plotted and compared by using the log-rank test. A multivariate analysis was done by using the Cox proportional hazards model. Results: Statistically significant differences in survival rates were noted based on gender, depth of invasion, lymph node metastasis, distant metastasis, stage, location of tumor, macroscopic type, extent of gastric resection, curability of surgery, and adjuvant chemotherapy. Five-year survival rates of patients who received EPIC and systemic chemotherapy were 49 per cent and 25 per cent, respectively (P=0.009). A multivariate analysis revealed that invasion of an adjacent organ, lymph node metastasis, total gastrectomy, and palliative surgery were poor independent prognostic factors. Also, EPIC had a marginal prognostic value (P=0.056). Conclusion: Perioperative intraperitoneal chemotherapy can possibly be one of the independent prognostic indicators in case of serosa-positive gastric cancer. (J Korean Gastric Cancer Assoc 2004;4:89-94)

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.41.3-42
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• 2016

New CCD photometric observations of GX Aur have been made between 2004 and 2015. Our light curves are the first ever compiled and display the variable O'Connell effect. The light variations are satisfactorily modeled by including time-varying cool-spots on the component stars. Our light curve synthesis indicates that the eclipsing pair is an A-type contact binary with parameters of i = 81.1 deg, ${\Delta}T=36K$, q = 0.950 and f = 46%. Including our 25 timing measurements, a total of 83 times of minimum light spanning about 66 yr were used for a period study. It was found that the orbital period of GX Aur has varied due to two periodic oscillations superposed on an upward-opening parabolic variation. The long-term period increase rate is deduced as $+9.636{\times}10^{-10}d\;yr^{-1}$, which can be produced as a mass transfer from the secondary star to the primary at a rate of $3.136{\times}10^{-6}M_{\odot}\;yr^{-1}$, among the largest rates for contact systems. The periods and semi-amplitudes of the two periodic variations are about $P_3=8.7yr$ and $P_4=21.2yr$, and $K_3=0.011d$ and $K_4=0.017d$, respectively. The most reasonable explanation for both cycles is a pair of light-travel-time effects driven by the possible existence of an unseen third and fourth components with projected masses of $M_3=0.91M_{\odot}$ and $M_4=1.09M_{\odot}$ in eccentric orbits of $e_3=0.13$ and $e_4=0.73$. Because no third light was detected in the light curve synthesis, each circumbinary object could be a compact star or a binary itself.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.585-586
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• 2015

4U 1323-62, a low mass X-ray binary with an orbital period of 2.94 hr, exhibits periodic X-ray dips, which are due to absorption by the bulge of the outer accretion disk. The purpose of this study is to search for orbital period changes using archived X-ray data over a time span of 20 years. We present our preliminary results from analyzing light curves observed by RXTE, BeppoSAX, XMM-Newton and Suzaku. We used the method proposed by Hu et al. (2008) to estimate dip center time and adopted the Observed - Calculated method to measure changes in period. We obtained an orbital period of 2.941917(36) hr and a period derivative of $\dot{P}_{orb}/P_{orb}=(-9.9{\pm}3.5){\times}10^{-7}yr^{-1}$. The F-test result shows that the quadratic ephemeris is describes the evolution of the dip phases better than the linear ephemeris at a greater than 95% confidence level. More X-ray data collected from the early 80s will be included to further refine the orbital ephemeris.

• Membrane Journal
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• v.5 no.2
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• pp.89-96
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• 1995

The monolayer characteristics of phosphate amphiphiles with azobenzene at air/water interface were studied by the measurment of $\pi-A$ curves and absorption spectra. Immediately after being spread on the water surface, these amphiphiles having strong intermolecular hydrogen bonding interactions showed the typical absorption spectra which resulted from domain formation. But the aggregated domains could be controlled by changing the subphase conditions (adding bulky salt and rasing pH). Addition of metal ions in subphase changes the molecular orientation of monolayer. As the metal ion charge increases ($1\leq2$ < 3 < 4 valence), the absorption maximum (310nm) of the amphiphile with azobenzene shifts to a longer wavelength (350nm) which means that the orientation of the amphiphile is tilted. These results suggest that the molecular orientation, and furthermore the aggregation state of monolayer can be possibly controlled by the interaction of metal ions with different charge types.