Jong Wan Park

Seoul National University Hospital, Sŏul, Seoul, South Korea

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Publications (5)12.39 Total impact

  • Jae Suk Lee, Jong Wan Park, Sang Mo Shin
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    ABSTRACT: A new micro catalytic gas sensor for detecting inflammable gases was fabricated on a Si wafer by thin film deposition and Si anisotropic etching. The size of the fabricated sensor was 3.25×2.20 mm2. The sensor was designed to consist of a catalyst with high surface area and a heater with high temperature coefficient of resistance (TCR) in order to acquire high sensitivity to gases of interest. The TCR of the sensor was found to be 3844 ppm °C−1. Sensitivities to methane and butane gases were 2.2 mV 1000 ppm−1 and 8.9 mV 1000 ppm−1, respectively. The optimum applied Wheatstone bridge power was varied in the range from 350 to 400 mW, being much smaller than those of commercial pellistors. It was also found that sensitivities to methane and butane gas were decreased by increasing humidity.
    Sensors and Actuators B Chemical 12/1997; 45(3):265-269. DOI:10.1016/S0925-4005(97)00322-5 · 3.84 Impact Factor
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    ABSTRACT: Although the use of sheep in total artificial heart (TAH) implantation has many advantages, they are known to show a significant morbidity rate on cardiopulmonary bypass (CPB); this has been considered to be a major limiting factor in using them for TAH experiments. We conducted a series of ovine CPB experiments to evaluate the sheep's pathophysiological response to CPB. CPB-related hemolysis, bleeding, and lung dysfunction were analyzed in 5 sheep, which had undergone CPB, used at our hospital for TAH implantation. Four of the 5 sheep survived the experimental procedures, and 3 of them survived on a long-term basis. Unacceptable degrees of hemolysis related to CPB were not observed. Postoperative bleeding was not remarkable, and coagulation test results did not show significant abnormal findings. Acute lung injuries of a mild to moderate degree were found mainly at the microscopic level, but rarely had clinical significance. In conclusion, this experiment suggests that sheep can be used for the animal model for TAH implantation with acceptable risk on CPB circuits and techniques are used.
    Artificial Organs 03/1997; 21(2):154-9. DOI:10.1111/j.1525-1594.1997.tb00353.x · 1.87 Impact Factor
  • Seoghyeong Lee, Jong‐Wan Park
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    ABSTRACT: The effect of fluorine addition on silicon oxide film properties as a function of SiF 4 /O 2 gas flow ratio was investigated. The films were deposited by using electron cyclotron resonance plasma chemical vapor deposition with SiF 4 and O 2 as source gases diluted in Ar. Characterization of films was carried out in terms of various gas flow ratios (SiF 4 /O 2 =0.2–1.0). The microwave power and substrate temperature during deposition were fixed at 700 W and 300 °C, respectively. The chemical bonding structure of the films was evaluated by Fourier transform infrared spectroscopy (FTIR), fluorine concentration by x‐ray photoelectron spectroscopy, and refractive index by ellipsometry. The dielectric constant was determined from C–V measurements at 1 MHz. FTIR spectra show that as the fluorine concentration increased, the intensities of the Si–F bonding peak and the shoulder peak (at around 1160 cm<sup>-1</sup>) of the Si–O stretching mode both increased. Refractive index and deposited film density decreased with increasing SiF 4 /O 2 gas flow ratio. The SiOF film deposited at a SiF 4 /O 2 gas flow ratio of 1.0 exhibited a fluorine content of 11.8 at. % and a dielectric constant of 3.14. © 1996 American Institute of Physics.
    Journal of Applied Physics 12/1996; 80(9-80):5260 - 5263. DOI:10.1063/1.363512 · 2.19 Impact Factor
  • Seok Ryong Jeon, Sung Wook Han, Jong Wan Park
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    ABSTRACT: Effect of high temperature annealing in the temperature range of 600–900 °C on the electrical properties and microstructure of tantalum pentoxide (Ta 2 O 5 ) thin film deposited by plasma‐enhanced chemical vapor deposition (PECVD) was studied. Leakage characteristics of the Ta 2 O 5 thin film annealed at 600 °C were found to be the best in this study. However, it was observed that the leakage current in the polycrystalline Ta 2 O 5 thin film decreased with increasing the annealing temperature above 800 °C after a peak for 700 °C annealing. The dielectric constant of the annealed Ta 2 O 5 thin film was 26 after annealing at 600 °C, and decreased with the same tendency as the leakage current characteristics. Transmission electron microscopy (TEM) and x‐ray diffraction (XRD) analysis indicated that the microstructure of the Ta 2 O 5 thin film annealed above 800 °C was of δ‐Ta 2 O 5 with hexagonal crystal structure. Furthermore, TEM and AES observations revealed that Ta–O–Si transition layers were formed between the annealed Ta 2 O 5 thin film and Si substrate. The electrical properties of the Ta 2 O 5 films are discussed in terms of interface modification and film densification due to rapid thermal annealing treatment. © 1995 American Institute of Physics.  
    Journal of Applied Physics 07/1995; 77(11-77):5978 - 5981. DOI:10.1063/1.359180 · 2.19 Impact Factor
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    ABSTRACT: Tantalum oxide film formation by plasma-enhanced chemical vapour deposition (PECVD) using TaCl5 as a source material was examined. The effects of deposition temperature on the formation, structure and electric properties of the Ta2O5 film were investigated for Al/Ta2O5/ p-Si (MTS) capacitors. The deposition rate and refractive index increased with increasing deposition temperature. It was found that the structure of Ta2O5 deposited by PECVD was amorphous as-deposited. However, crystalline -Ta2O5 of hexagonal structure was formed by a 700 C, 1 h heat treatment in argon. Capacitance and relative dielectric constant of the PECVD Ta2O5 were found to be 2.54 fF m–2 and 23.5, respectively. The PECVD films obtained in this study have higher dielectric constants and remarkably better general film characteristics than those obtained by other deposition methods.
    Journal of Materials Science 12/1993; 29(6):1545-1548. DOI:10.1007/BF00368923 · 2.31 Impact Factor