• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.639-644
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• 2011

A simple and highly sensitive chemiluminescence method to determine norfloxacin (NFLX) has been proposed by measuring the chemiluminescence (CL) intensities using a flow injection (FI) system. The CL intensity of the luminol-$H_2O_2$ system is strongly enhanced by the addition of Cu (II) in alkaline condition. The CL intensity is substantially increased after the injection of NFLX into the luminol-$H_2O_2$-Cu (II) system. The enhancement effect is attributed to a catalytic effect of Cu (II) due to the interaction with NFLX which forms a complex with the catalyst. Under the optimal conditions, the sensitizing effect of the CL intensity is proportional to the concentration of NFLX in the range of $1.5{\times}10^{-9}-5.9{\times}10^{-7}molL^{-1}$ (r = 0.9994) with a detection limit ($3{\sigma}$) of $2.98{\times}10^{-10}molL^{-1}$. The proposed method had good reproducibility with the relative standard deviation (RSD, n = 5) of 1.6% for $1{\times}10^{-7}molL^{-1}$ of NFLX. The possible reaction mechanism of the CL reaction is also discussed. This method has been successfully applied for the determination of trace amount of NFLX in pharmaceutical preparations and serum samples.

• Journal of the Korean Chemical Society
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• v.55 no.6
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• pp.932-935
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• 2011

Using tetrabutyl titanate as precursor, $Eu^{3+}$ doped $TiO_2$ nano-powder was prepared by sol-gel method, the nature of luminescence of nano-powder was studied. The interaction of chlorpyrifos with $Eu^{3+}$ doped $TiO_2$ was studied by absorption and fluorescence spectroscopy. The results indicated the fluorescence intensity of $Eu^{3+}$ doped $TiO_2$ was quenched by chlorpyrifos and the quenching rate constant ($k_q$) was $1.24{\times}10^{11}\;L/mol{\cdot}s$ according to the Stern-Volmer equation. The dynamics of photoinduced electron transfer from chlorpyrifos to conduction band of $TiO_2$ nanoparticle was observed and the mechanism of electron transfer had been confirmed by the calculation of free energy change (${\Delta}G_{et}$) by applying Rehm-Weller equation as well as energy level diagram. A new rapid method for detection of chlorpyrifos was established according to the fluorescence intensity of $Eu^{3+}$ doped $TiO_2$ was proportional to chlorpyrifos concentration. The range of detection was $5.0{\times}10^{-10}-2.5{\times}10^{-7}mol/L$ and the election limit ($3{\sigma}$) was $3.2{\times}10^{-11}$ mol/L.

• Journal of the Korean Geotechnical Society
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• v.25 no.6
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• pp.5-16
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• 2009

The is study is to evaluate the small strain shear modulus ($G_{max}$) of Busan clay using in-situ penetration tests. A series of dilatometer tests (DMT) and piezocone penetration tests (CPTu) are performed at Busan newport and Noksan sites, and hybrid oedometer tests are also carried out on the specimens obtained from both sites. The $G_{max}$ is evaluated from the shear wave velocity ($V_s$) measured by the bender elements installed at the boundary of oedometer cell. By analyzing these data, the relationship of $G_{max}$ and state variables, such as confined stress and void ratio, is developed. The analysis of lab and in-situ test results reveals that the ratio of $G_{max}$ to $q_t$ is inversely proportional to the plasticity index while the ratio of $G_{max}$ to $E_D$ has a linear relationship with ($I/I_D$)$(p_a/{\sigma}'_v)^{0.5}$. Two correlations suggested in this study, based on CPT and DMT results, appear to provide reasonable predictions of the small strain shear modulus.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.4
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• pp.773-779
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• 2011

The width of a submarine's turbulent wake, using Shear-free and Ship wake theory, is proportional to $x^n,\;({\frac{1}{5}}{\leq}n<{\frac{1}{2}})$ If we assume submarine's length, width, velocity are 65m, 6.5m, 6kts respectively, and the minimum diffusion of turbulent wake ; ${\infty}\;x^{1/5}$, the width of wake behind the submarine is about 20m at 1.2km, 30m at 15km when there is no breaking waves on the sea surface. However, in the case of breaking waves, it is very limited to identify submarine's wake on the sea surface because wind generated turbulent wake has higher turbulent kinetic energy than that of submarine's wake. As a result, there is a high possibility to detect submarine's wake on the sea surface in the shallow water such as the Yellow-Sea using a proper detection method such as SAR. This means that in anti-submarine operations, non-acoustic sea surface serveillance applied turbulent wake will be very effective way to detect a submarine in near future. To do this we have to develop exact theory of submarine's turbulent wake above all.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.20 no.3
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• pp.71-81
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• 2007

Objective : In this study, herbal medicine(GJE, Gardenia jasminoides Ellis; HCT, Houttuynia cordata Thunb.; CIL, Chrysanthemum indicum Linne; PMS,Paeonia moutan Sims, P. subfruticosa Makino; APL, Agrimonia pilosa Ledebour) were screened for their inhibitory activities against Tyrosinase and PMA plus A23187-induced $TNF-{\alpha}$, IL-6, IL-8 productions in HMC-1 cells to reveal their skin -whitening and anti-allergic effect. Method : To investigate Tyrosinase inhibition we treated Mushroom Tyrosinase(Fluka, 93898) $10{\mu}{\ell}$ and 7.5mM Tyrosine (Sigma, T3754) $20{\mu}{\ell}$ with 80% ethanol medicine extracts. Then we observed 96well micro plate extinction at 490nm. In the next experiment, to investigate Anti-allergic effect we blended cultured Human Mast Cells(HMC-1) with medicine extracts. We treated the blended solution with Phorbol 12-myristate 13-acetate(PMA) and A23187, then observed $TNF-{\alpha}$, IL-6, IL-8 by ELISA (enzyme-linked immunosorbent assay) at 450nm. Results : In inhibiting Tyrosinase the results are as follows. 1. We observed 22% inhibition of Mushroom Tyrosinase at $500{\mu}g/m{\ell}$ concentration of GJE extracts. 2. We also could observe that the decreased Mushroom Tyrosinase activities in HCT, CIL extracts. In inhibiing $TNF-{\alpha}$, IL-6, IL-8 productions in HMC-1 cells the results are as follows. 1. Of the extracts examined, HCT, PMS, APL extracts showed over 50% inhibitions of Cytokines at $200{\mu}g/m{\ell}$ concentration. 2. In particular, APL extracts showed the best inhibitory effect on Cytokine productions in a dose-dependent manner. Conclusion : These results suggest that GJE extracts contributes to the anti melanin activities and represent a potential source of whitening agent. Thus these herbal medicines suggest novel drugs on anti-allergic effects.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.1
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• pp.63-73
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• 1987

This study is a part of the research on the coupled vibration of train wheel with the stepped thickness and rail. The research was conducted for the purpose of examining the dynamic characteristics of train wheel at the running state and preventing the vibrations of the high speed railway. The stress at the boundary surface of web and rim, .sigma.$_{c}$, was analyzed in consideration of the uniform In-plane compressive stress depending on the conditions of rolling and the In-plane compressive stress depending on the rotation of train wheel. Then the equation of transverse vibration of the annular plate with the stepped thickness was analyzed by Rayleigh-Ritz's method. As a result of study, it was known that the rotational speed increase the natural frequency slightly and the acceleration level highly while the reaction force between train wheel and rail decrease the natural frequency linearly and the critical buckling is generated at n=1.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.20-27
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• 1998

According as the member of the automobile body structure have been thinned their thickness and have become high strength, each part of the body structure has been put more severe stress condition. And, because fatigue strength of the spot welded lap joint is influenced by its geometrical and mechanical factors, welding condition and etc., there needs a quantitative and systematic evaluation method for them. In this study, by considering nugget edge of the spot weld part of the IB-type spot welded lap joint under tension-shear load to the ligament crack. fatigue strength of various IB-type spot welded lap joints was estimated with the stress intensity factor(S.I.F.) KIII which is fracture mechanical parameter. We could find that fatigue strength evaluation of the IB-type spot welded lap joints by KIII is more effective than the maximum principal stress ($\sigma$1max) at edge of the spot weld obtained from FEM analysis.

• Journal of the Korean Vacuum Society
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• v.6 no.4
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• pp.293-297
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• 1997

Using trace etching method in this study, we measure the energy of argon ions generated in VEBA System which is composed of Marx Generater and Pulse Forming Line. In this system the electron beam of 240 kV, 30 kA, 60 ns is generated. Argon ions are formed through the electron beam ionization of a gas cloud injected by a fast puff valve. Thus argon ions are accelerated into vacuum drift tube by a virtual cathode and seperated with electron beam, consequently, they heat the trace etching plates made of aluminum thin films. The energy of argon ions are determined by the number of aluminum thin films penetrated by the ions. This experimental value corresponds with the theoretical value.

• The Korean Journal of Pharmacology
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• v.7 no.1
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• pp.37-52
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• 1971

It has been demonstrated repeatedly that the administration of ethionine, a methionine analogue, will produce destruction of pancreatic tissue and liver cells. Destruction of acinar cells of pancreas by the administration of excess methionine similar to that seen after feeding diets supplemented with ethionine was also reported, but the liver was not involved by this amino acid. In an attempt to reproduce the results of these investigators the tissue damages were found to be slight and seen only irregulary in rats receiving ethionine on a complete diet and the result of tissue damages by excess methionine were also controversial. The present studies describe the toxicity of dietary supplemented ethionine and methionine to liver and pancreas in rats fed a low protein diet. Hundred five albino rats weighing around 120 gm were divided into three groups as follows; 1) Control group: A low protein diet containing 8% casein was fed throughout the experimental period. 2) Methionine group: A low protein diet (7% casein) supplemented with 1% methionine was used. 3) Ethionine group: A similar diet as methionine group except the supplementation of 1% ethionine instead of methionine was used. Five animals per wee from each group were killed for 6 weeks. The liver and pancreas were fixed in 10% formalin and histologic sections were prepared and stained with hematoxylin eosin. Serum amylase was expressed as much of glucose liberated from a starch substrate. The glucose was determined by the method of Nelson (1944). Serum glutamic pyruvic transaminase (SGPT) and glutamic oxaloacetic transaminase (SGOT) were determined by the technique described in Sigma Bulletin.

• Archives of Pharmacal Research
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• v.14 no.2
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• pp.137-142
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• 1991

The structure of a $\beta$-allyl type phenylpropanoid was determined by single crystal X-ray diffraction analysis. The compound was recrystallized from a mixture of n-hexane and benzene in monoclinic crystal system with a = 24.782 (2), b = 10.537 (1), c = 7.871 (1) ${\AA}, \beta=95.74$ (1)$^\circ, $D_x$=1.216, $D_m$=1.22g/$cm^3$, space group $P2_1/a$, and Z=4. The structure was solved by direct method and refined by least-squares procedure to the final R value of 0.054 for 2824 observed reflections {$F{\geq}3\sigma(F)$}. The molecular geometry shows a most stable trans-form with respect to the bulky phenyls, and this conformation is settled by an intramolecular hydrogen bond. In the crystal, the molecules are arranged along with the screw axis, and stabilized by the $O{\cdot}H{\cdots}O$ type intermolecular hydrogen bonds. The other intermolecular contacts appear to be the normal van der Waals' interactions. The compound is a dimeric phenylpropanoid, and belongs to the neolignan analogues.