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Oral Absorption of Cefoperazone Pivaloyloxymethyl Ester
최영욱,박기배,최승호,김종갑,Choi, Young-Wook,Park, Gee-Bae,Choi, Seung-Ho,Kim, Johng-Kap 한국약제학회 1988 Journal of Pharmaceutical Investigation Vol.18 No.4
Pivaloyloxymethyl ester of cefoperazone was synthesized by treating sodium cefoperazone with chloromethyl pivalate and its chemical structure was determined by spectroscopic trials. The pharmaceutical properties of the ester were investigated to assess its potential as a prodrug of cefo perazone. Cefoperazone pivaloyloxymethyl ester was microbiologically inactive itself in vitro, but hydrolyzed into the parent drug in vivo. After a single oral dose of each drug to rabbits, serum concentrations of cefoperazone were determined by high performance liquid chromatographic assay. The ester showed higher and more sustained blood level than cefoperazone. Therefore, the total area under the serum concentration-time curve of the derivative was 16.8 times larger than that of the parent drug.
Oil-Water Interface Transfer of Cefoperazone Pivaloyloxymethyl Ester
최영욱,김종갑,Choi, Young-Wook,Kim, Johng-Kap 한국약제학회 1989 Journal of Pharmaceutical Investigation Vol.19 No.1
Kinetic and thermodynamic aspects of the interface transfer of cefoperazone and its pivaloyloxymethyl ester were studied in a two-phase system composed of aqueous buffers and n-octanol by using the absolute reaction rate theory. In terms of the net thermodynamic parameters for the process, ${\Delta}S$ increased and ${\Delta}F$ decreased as the lipophilicity increased. With the increased ratio of forward $(k_f)$ to backward rate constants $(k_b)$, the ester was more lipophilic than cefoperazone, but the aqueous solubility was reduced.
Sputtering technique for magnessium oxide thin films
최영욱(Choi young wook) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7
A high rate deposition sputtering process of magnesium oxide thin film in oxide mode has been developed using a 20 ㎾ unipolar pulsed power supply. The power supply was operated at a maximum constant voltage of 500 V and a constant current of 40 A. The pulse repetition rate and the duty were changed in the ranges of 10~50 ㎑ and 10~60%, respectively. The deposition rate increased with rising incident power to the target. Maximum incident power to the magnesium target was obtained by the control of frequency, duty and current. The deposition rate of a moving state was 9 ㎚ m/min at the average power of 1.5 ㎾.
최영욱(Young-Wook Choi) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.11
A hollow cathode which has extremely stable discharge characteristic has been developed. This is composed of the two separated lanthanum hexaboride (LaB?) of a disk type in the tube as the electron emitters. The way of design is of great advantage to extend the surface discharge area of the LaB?, which is also useful for optimal fixing of the LaB?. The hollow cathode is capable of producing 30 ㎾ (100 V, 300 A) of power continuously.
컨포멀 코팅된 PCB의 기포 검출을 위한 전처리 알고리즘
최영욱(Young-Wook Choi),이동희(Dong-Hee Lee),조성령(Sung-Ryung Cho),강동욱(Dong-Wook Kang) 대한전자공학회 2019 대한전자공학회 학술대회 Vol.2019 No.11
Since the conformal coating process on the PCB substrate is performed by solution spraying, bubbles may be generated in the substrate. The presence of bubbles has a critical impact on the life of the PCB, so a rigorous bubble inspection is essential before mounting the PCB. In this paper, we studied a method to improve the performance of bubble inspection by generating binary images suitable for bubble detection through pre-processing using two target images taken under different exposure conditions and a master image without bubbles.