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한지숙,박금수,조철호,고윤웅,윤진우,전상일 대한내과학회 1986 대한내과학회지 Vol.30 No.1
We retrospectively analyzed clinical and laboratory features of 58 patients with SLE for the survival and the factors which may have influenced the outcome from 1970 through 1983. The survival was calculated using the method of Merill and Shulman, taking the time of diagnosis and the onset of symptom as the starting point. We divided 58 patients with SLE into 2 groups, those whose survival was less than or equal to 2 years and those greater than 2 years, and compared clinical and laboratory features between them with particular emphasis on those factors which may have influenced the outcome. The results obtained as follows: 1) The estimated survival from diagnosis was 76.7% in 1 year, 62.3% in 2 years, 62.3% in 3 years, 59.6% in 4 years, 53.8% in 5 years and 50.6% in 10 years. The estimated survival from the onset of symptom was 65.5%, in 1 years, 59.54% in 2 years, 56.2% in 3 years, 52.2% in 4 years, 52.5% in 5 years, and 46.l% in 10 years. 2) There was a statisticaly significant difference in prognosis between 2 groups with regard to CNS involvement, serositis, and increased serum creatinine level(≥3.0mg/dl).
Preparation and in vivo evaluation of immediate-release pellet containing celecoxib solid dispersion
Chun-Woong Park,Nguyen-Thach Tung,Dao-Danh Son,김주영,이윤석,Seung-Yeop Kang,Shin-Ae Park,황규목,오택운,하정명,Sang-Cheol Chi,박은석 한국약제학회 2012 Journal of Pharmaceutical Investigation Vol.42 No.3
The aim of this study was to make use of small size of immediate-release (IR) pellet and amorphous state of solid dispersion to increase solubility of celecoxib (CLX), a drug in BCS class II. Primary, binary and ternary solid dispersions were developed to choose the final components for solid dispersion. A ternary novel solid dispersion was prepared by incorporation of one aqueous soluble polymer (povidone k17; PVP 17PF), Methacrylate copolymer-based gastric soluble polymer (Eudragit EPO) and one pH modulator (MgO). This combination was effective to increase solubility in pH 1.2 up to 25–30 %. The mechanismof solubility enhancement was proven by DSC, PRXD, and FT-IR. Accordingly, hydrogen bonding or electrostatic interaction of CLXwithPVP/EudragitEPOwas themain cause to formthe amorphous state of CLX within polymer cluster which increasing solubility of drug. Besides, MgO played an important role to change microenviroment for solid dispersion. Pellets containing this solid dispersion were prepared by extrusion and spheronization technique. Effect of four kinds of additive (calciumhydrogen phosphate dihydrate,NaHCO3,crospovidone, and sodium dodecyl sulfate) on dissolution of CLX from IR pellet was also determined. Because of highest dissolution rate, formulation using sodium dodecyl sulfate was used for pharmacokinetics study. Solid dispersion-IR pellet formulation presented bioequivalence and lower variability in comparison with reference product.
Park, Chun-Woong,Lee, Hyo-Jung,Oh, Dong-Won,Kang, Ji-Hyun,Han, Chang-Soo,Kim, Dong-Wook Dove Medical Press 2018 Drug design, development and therapy Vol.12 No.-
<P><B>Background</B></P><P>Norquetiapine (<I>N</I>-desalkyl quetiapine, NQ) is an active metabolite of quetiapine with stable pharmacokinetic and pharmacological properties. However, its short half-life is a drawback for clinical applications, and long-acting formulations are required.</P><P><B>Purpose</B></P><P>The objectives of this study were to prepare improved entrapment efficiency NQ freebase microspheres by the solvent evaporation method with poly(d,l-lactic-co-glycolic acid) (PLGA) as a release modulator and to evaluate their physicochemical and in vitro/in vivo release properties.</P><P><B>Methods</B></P><P>NQ freebase PLGA (1:5 w/w) formulations were prepared by the oil-in-water (o/w) emulsion–solvent evaporation method. A solution of the drug and PLGA in 9:1 v/v dichloromethane:ethanol was mixed with 0.2% polyvinyl alcohol and homogenized at 2,800 rpm. The emulsion was stirred for 3 h to dilute and evaporate the solvent. After that, the resulting product was freeze-dried. Drug-loading capacity was measured by the validated RP-HPLC method. The surface morphology of the microspheres was observed by scanning electron microscopy (SEM), and the physicochemical properties were evaluated by differential scanning calorimetry, powder X-ray diffraction, and Fourier-transform infrared spectroscopy particle size distribution. The in vitro dissolution test was performed using a rotary shaking bath at 37°C, with constant shaking at 50 rpm in sink condition.</P><P><B>Results</B></P><P>The NQ freebase microspheres prepared by o/w emulsion-solvent evaporation showed over 30% efficiency. NQ was confirmed to be amorphous in the microspheres by powder X-ray diffraction and differential scanning calorimetry. Special chemical interaction in the microspheres was not observed by FT-IR. The in vitro dissolution test demonstrated that the prepared microspheres’ release properties were maintained for more than 20 days. The in vivo test also confirmed that the particles’ long acting properties were maintained. Therefore, good in vitro–in vivo correlation was established.</P><P><B>Conclusion</B></P><P>In this study, NQ freebase-PLGA microspheres showed potential for the treatment of schizophrenia for long-periods.</P>
The Synthesis and Photocatalytic activity of Carbon Nanotube-mixed TiO<sub>2</sub> Nanotubes
Park, Chun Woong,Kim, Young Do,Sekino, Tohru,Kim, Se Hoon The Korean Powder Metallurgy Institute 2017 한국분말재료학회지 (KPMI) Vol.24 No.4
The formation mechanism and photocatalytic properties of a multiwalled carbon nanotube (MWCNT)/$TiO_2$-based nanotube (TNTs) composite are investigated. The CNT/TNT composite is synthesized via a solution chemical route. It is confirmed that this 1-D nanotube composite has a core-shell nanotubular structure, where the TNT surrounds the CNT core. The photocatalytic activity investigated based on the methylene blue degradation test is superior to that of with pure TNT. The CNTs play two important roles in enhancing the photocatalytic activity. One is to act as a template to form the core-shell structure while titanate nanosheets are converted into nanotubes. The other is to act as an electron reservoir that facilitates charge separation and electron transfer from the TNT, thus decreasing the electron-hole recombination efficiency.
Scaling Down Characteristics of Vertical Channel Phase Change Random Access Memory (VPCRAM)
Chun Woong Park,Chongdae Park,Woo Young Choi,Dongsun Seo,Cherlhyun Jeong,Il Hwan Cho 대한전자공학회 2014 Journal of semiconductor technology and science Vol.14 No.1
In this paper, scaling down characteristics of vertical channel phase random access memory are investigated with device simulator and finite element analysis simulator. Electrical properties of select transistor are obtained by device simulator and those of phase change material are obtained by finite element analysis simulator. From the fusion of both data, scaling properties of vertical channel phase change random access memory (VPCRAM) are considered with ITRS roadmap. Simulation of set reset current are carried out to analyze the feasibility of scaling down and compared with values in ITRS roadmap. Simulation results show that width and length ratio of the phase change material (PCM) is key parameter of scaling down in VPCRAM. Thermal simulation results provide the design guideline of VPCRAM. Optimization of phase change material in VPCRAM can be achieved by oxide sidewall process optimization.
De-soda Process Using Silica for Fabrication of Low Soda Alumina Powder
Park, Sang-Chun,Kim, Dae-Woong,Heo, In-Woong,Lee, Sang-Jin The Korean Ceramic Society 2015 한국세라믹학회지 Vol.52 No.3
Low soda alumina powder was fabricated using silica (${\alpha}$-quartz) as an agent for removing soda components in the alumina. Quartz powder 2 mm in size was added to aluminum hydroxide obtained through the Bayer process, and then the mixture was heated at various temperatures. Finally, the heat-treated powders were sieved for classification. In this study, the effects of the quartz amount and heating temperature on the mechanism of removing soda were examined. A minimum soda content of 0.005 wt% was observed at the conditions of 15 wt% quartz (based on $Al(OH)_3$ amount) heat-treated at $1600^{\circ}C$ for 8 h. The soda components, such as $Na_2O$, NaOH, and $Na_2CO_3$, in alumina were ionized and activated at high temperature, and this facilitated the reaction with quartz silica and alumina producing nepheline. The advantages of using quartz include low iron content and low cost in comparison with the conventional de-soda process using chamotte, another silicate mineral.
Park, Chun Woong,Choi, Woo Young,Lee, Jong-Ho,Cho, Il Hwan Institute of Physics 2013 Semiconductor science and technology Vol.28 No.11
<P>Ambipolar characteristics of tunneling FETs have been improved by introducing a novel structure which contains dielectric sidewall in the gate region. In the ambipolar operation mode, gate field effect on intrinsic-drain junction region can be reduced with dielectric sidewall. As a result, ambipolar state tunneling probability is decreased at the intrinsic-drain junction. Since the sidewall region is located near the drain region, tunneling probability of source-intrinsic region is not affected by dielectric sidewall. This asymmetric characteristics means only ambipolar current of tunneling FETs can be prohibited by dielectric sidewall. Reduction of ambipolar characteristic of proposed structure has been evaluated with dimension and location of dielectric sidewall. Quantitative analysis of ambipolar characteristics is also investigated with tunneling.</P>
Park, Chun-Woong,Kim, Ju-Young,Rhee, Yun-Seok,Oh, Tack-Oon,Ha, Jeong-Myung,Park, Eun-Seok Informa Healthcare 2012 Drug development and industrial pharmacy Vol.38 No.10
<P>The objective of this study was to achieve an optimal formulation of spray dried matrix type controlled-release (MTCR) microparticles containing tamsulosin hydrochloride for orally disintegrating tablet. To control the release rate of tamsulosin hydrochloride, Acrylate-methacrylate copolymer (Eudragit<SUP>®</SUP> L-100 or Eudragit<SUP>®</SUP> S-100) and ethylcellulose were employed on the composition of MTCR microparticles. Physicochemical properties of MTCR microparticles such as particle size and SEM were characterized. Pharmacokinetic parameters of tamsulosin hydrochloride were evaluated in the rats after oral administration. MTCR microparticles were spherical microparticles of around 10 µm diameter with a corrugated surface. ODTs containing MTCR microparticles were disintegrated within 30 s and MTCR microparticles were able to control the release rate of tamsulosin hydrochloride following Fickian diffusion mechanism. The <I>in vitro</I> release rates of tamsulosin hydrochloride from MTCR microparticles were proportional to the ratio of Acrylate-methacrylate copolymer to ethylcellulose. Moreover, MTCR microparticles retarded the <I>in vivo</I> release rate of tamsulosin hydrochloride without reducing the bioavailability. Our results suggest that MTCR microparticles may be potential oral dosage forms to control the release and to improve the bioavailability of tamsulosin hydrochloride.</P>