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PVDF와 PZT 混合材料의 電氣機械結合係數에 관한 硏究
趙廷台,李明敎 釜山工業大學校 1995 論文集 Vol.37 No.-
It has been known piezoelectric activity can be generated in synthetic polymer films subjected to a strong DC electric field at elevated temperatures. Polyvinylidene fluoride(PVDF) is best known and commercially most attractive which has been utilized as an active element in many applications ranging from infrared detector to ultrasonic transducers. Lead Zirconate-Lead Titanate(PZT) powders are made from the mole ratio of Pb(Mn1/3Sb2/3)0.08Ti0.49Zr0.425O3 by mixing PbCl2, ZrOCl2, TiCl4, MnCl2 and SbCl3. PVKF-PZT powders are mixed with aceton liquid and make of disc type in diameter 20mm, thickness 0.3mm by the pressure of 20dg/㎠. Poling is done by appling a strong electric field 20kV/cm. Dielectric constant of composite by the mixture ratio is about 30-50 and the value of electro-mechanical coupling factor k is 0.48.
田炳實,趙正萬,김종교 全北大學校 1978 論文集 Vol.20 No.-
Many advantages are to be obtained from the use of negative feedback, at the cost of gain. These are as follows; the increase of frequency band-width, the improvement of amplification stability, the decrease of nonlinear distortion and noise, and the simplicity of impedance matching, etc. Many of electronic devices require wide frequency bands. For example, a cathode-ray oscilloscope, in order to cover the frequency range of 0 to 20 MHZ, requires an amplifier with the frequency band over 20 MHZ. Moreover, communication devices require the very wide frequency bands of several hundreds MHZ. A negative feedback is used widely in order to obtain the devices with wide frequency bands. This paper describes the analysis and the practical synthesis procedure of the design of shaped gain, wide-band, impedance matched, dual loop feedback amplifier that uses a cascade of two common emitter transistor stages. An amplifier is designed to have the lower cut-off frequency of 50MHZ. Experimental results are coincident to the specified characteristics as well.
백창렬,이동건,최정현,정현화,조유경,박훈준,이승훈,박윤희,이교영,민우성,김춘추,신완식 대한감염학회 2001 감염 Vol.33 No.4
As a result of the enlarging pool of unvaccinated children and young adults, there has been an increase in measles in our countries. In these situation, it has been reported that measles associated pneumoinia is easily complicated with fatal respiratory failure, espycially in immunocompromised patients. Herein we report the case of lethal measles pneumonia after allogenic hematopoietic stem cell transplantation in adults proven by autopsy. Recently, one case of measles was encountered in 39-year-old female patients after allogenic bone marrow transplanted case (chronic myelogenous leukemia), who progressed into interstitial pneumonia pattern, despite treatment including antibiotics, immunoglobulin. The patient died of giant cell pneumonia compatible with that of measles which was comfirmed in the section of necropsy lung specimen. (Korean J Infect Dis 33:301∼309, 2001)
Cho, Jung-Kyo,Hong, Ki-Yun,Park, Jung Won,Yang, Han-Kwang,Song, Soo-Chang Informa Healthcare 2011 Journal of drug targeting Vol.19 No.4
<P>2-Methoxyestradiol (2-ME) has been reported to have antiangiogenic and antitumor activity. Its biomedical application is limited due to its poor water solubility resulting in its low bioavailability. Poly(organophosphazenes) containing <SMALL>L</SMALL>-isoleucine ethyl ester, ethyl-2-(<I>O</I>-glycyl)lactate, and α慣-amino-ω?-methoxy-poly(ethylene glycol) 550 were synthesized having <I>M</I><SUB>W</SUB> of 35-??38 ??kDa and polydispersity index of 2.38-??2.73. Using a viscometer, the thermosensitivity useful for locally injectable drug delivery was verified. The aqueous polymer solution showed a sol state at a low temperature and transformed to a gel state at body temperature. The polymer solution (10 wt%) enhanced the solubility of 2-ME by about 10<SUP>4</SUP> times compared to that of phosphate buffered saline. 2-ME was released from the hydrogel mainly by diffusion, hydrophobic interaction, and surface erosion of the matrix. This release profile could be confirmed through an <I>in vitro</I> release test as a function of polymers and the concentration of 2-ME in hydrogels. By monitoring tumor volume and CD31 immunohistochemical staining in mouse orthotopic breast tumor (MDA-MB-231) model, it was found that the hydrogel containing a relatively low concentration (15 ??mg/kg) of 2-ME showed the improved antitumor and antiangiogenic activity relative to the original formulation. This research suggests that the developed formulation of poly(organophosphazenes) may have injectable carrier potentials for 2-ME and other lipophilic drugs.</P>
Cho, Jung-Kyo,Park, Wooram,Na, Kun Wiley Subscription Services, Inc., A Wiley Company 2009 Journal of applied polymer science Vol.113 No.4
<P>Water-insoluble pullulan-g-poly(L-lactide) (PUPL) was successfully synthesized via a one-pot method in the presence of triethylamine in dimethyl sulfoxide, in an effort to design a novel anticancer agent carrier. Three samples (designated as PUPL 1, 2, and 3) were obtained, which differed in the moles of lactides grafted to the pullulan. The degrees of grafted lactide per 1 glucose unit in pullulan were 0.68, 0.60, and 0.45 for PUPL 1, 2, and 3, respectively. These copolymers were dissolved in several organic solvents, including dimethyl sulfoxide, acetone, and ethanol, but were insoluble in water. The self-organized nanogels were then prepared from the polymers via dialysis. To study the organizing behavior of the polymers, their critical association concentrations were measured. Their values were 5.0, 15.9, and 52.9 mg/L for PUPL 1, 2, and 3, respectively. The results showed that lactide in the polymers could function as a hydrophobic moiety for the formation of self-organized nanogels. To estimate the potential of PUPL 1 as an anticancer drug carrier, we used doxorubicin (DOX) as a model drug. The DOX loading efficiencies of PUPL 1 were more than 52%, which differed with differing initial DOX concentrations. High loading resulted in slower DOX release as the result of increases in hydrophobic interaction. In conclusion, PUPL nanogels may prove useful as anticancer drug carriers because of their low critical association concentrations and the controlled DOX release rate © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009</P>
Cho, Jung‐,Kyo,Park, Jung Won,Song, Soo‐,Chang Wiley Subscription Services, Inc., A Wiley Company 2012 Journal of Pharmaceutical Sciences Vol.101 No.7
<P><B>Abstract</B></P><P>The biodegradable poly(organophosphazene) hydrogels were developed as a locally injectable drug carrier for a hydrophobic silibinin to overcome its limited bioavailability. The aqueous solution of poly(organophosphazene) enhanced the solubility of silibinin up to 2000 times compared with that of phosphate buffered saline (0.0415 vs. 84.55 mg/mL). Both aqueous polymer solutions with and without silibinin showed a sol–gel transition as a function of temperature. A faster <I>in vitro</I> degradation rate of the gel and drug release rate from the gel at pH 6.8 than those at pH 7.4 were observed when the degradation and release study on hydrogels were conducted at 37°C. Silibinin was sustainedly released from the hydrogel mainly by a diffusion‐controlled mechanism. The silibinin released from the hydrogel was shown to be effective considering the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. In the HT‐29 xenografted mice model, the intratumorally injected hydrogel containing silibinin exhibited a good antitumor effect in comparison with the control groups. The Western blotting indicated that one of the reasons for the enhanced antitumor effect of the hydrogel system was the sustained antiangiogenic effect of silibinin. The poly(organophosphazene) gels are expected to be an effective candidate of the locally injectable drug carrier for silibinin. © 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 101:2382–2391, 2012</P>
Combinatory RNA-Sequencing Analyses Reveal a Dual Mode of Gene Regulation by ADAR1 in Gastric Cancer
Cho, Charles J.,Jung, Jaeeun,Jiang, Lushang,Lee, Eun Ji,Kim, Dae-Soo,Kim, Byung Sik,Kim, Hee Sung,Jung, Hwoon-Yong,Song, Ho-June,Hwang, Sung Wook,Park, Yangsoon,Jung, Min Kyo,Pack, Chan Gi,Myung, Seun Springer-Verlag 2018 Digestive diseases and sciences Vol.63 No.7
Cho, Jung-Kyo,Hong, Ji Min,Han, Taesu,Yang, Han-Kwang,Song, Soo-Chang Informa UK Ltd. 2013 Journal of drug targeting Vol.21 No.6
<P>Although docetaxel (DTX) is an advanced taxoid, further augmentation of its properties is still required, such as improvement in its low aqueous solubility. Herein, we report the development of biodegradable/injectable poly(organophosphazene) (PPZ) hydrogels for the delivery of DTX without the use of organic solvents. An aqueous solution of PPZ containing α-amino-ω-methoxy-poly(ethylene glycol) (AMPEG) 750 instead of AMPEG 550 was prepared, thereby increasing the erosion capacity of the hydrogel by judicious balance of the hydrophobic/hydrophilic moieties. The safety of the hydrogel was demonstrated using a biocompatibility test. The PPZ aqueous solution (8 wt%) containing DTX exhibited a thermosensitive sol-gel-sol transition that was independent of the concentration of DTX (1-3 mg/mL). The <I>in vitro</I> release study indicated that the dominant release mechanism was either erosion or diffusion/erosion-controlled release depending on the DTX content of the hydrogel. The <I>in vivo</I> anticancer effect of the intratumorally injected PPZ system in human gastric cancer cell-xenografted mice was evaluated, which demonstrated a significantly (<I>p</I> < 0.01) enhanced effect of the DTX-PPZ hydrogel system compared to the control (DTX solution, i.v.). In conclusion, the PPZ hydrogel may be a promising candidate for DTX delivery, affecting a decrease in the size of tumors with little toxicity prior to exeresis.</P>