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Thermodynamic analysis on the chemical vapor deposition process of Ta-C-H-Cl system

  • Kim, Hyun-Mi;Shim, Kwang Bo;Lee, Jung-Min;Lee, Hyung-Ik;Choi, Kyoon
    • Journal of Ceramic Processing Research
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    • v.19 no.6
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    • pp.519-524
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    • 2018
  • Carbon/carbon composites (C/C) have been widely studied in the aerospace field because of their excellent thermal shock resistance and specific strength at high temperature. However, they have the problems that is easily oxidized and deteriorated under atmospheric environment. In order to overcome these shortcomings, the CVD coating of ultra-high-temperature ceramics to C/C has become an important technical issue. In this study, thermodynamic calculations were performed to TaC CVD coating on C/C by FactSage 6.2 program. The Ta-C phase diagrams were constructed with the results of thermodynamic calculations in the Ta-C-H-Cl system. Based on the Ta-C phase diagram, the experimental conditions were designed to confirm the deposition of various phases such as TaC single phase, TaC + C and $TaC+Ta_2C$ by varying the composition of Ta/C ratio. The deposited films were found to be in good agreement with the predicted phases.

Molecular dynamic studies for elastic constant of SiC crystal at high temperature (고온에서 SiC 결정의 탄성율에 대한 분자동역학연구)

  • Park, B.W.;Shin, H.R.;Kim, J.H.;Im, J.I.
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.20 no.5
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    • pp.232-236
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    • 2010
  • Silicon carbide (SiC) ceramics are widely used in the application of high-temperature structural devices due to their light weight as well as superior hardness, fracture toughness, and temperature stability. In this paper, we employed classical molecular dynamics simulations using Tersoff's potential to investigate the elastic constants of the SiC crystal at high temperature. The stress-strain characteristics of the SiC crystal were calculated with the LAMMPS software and the elastic constants of the SiC crystal were analyzed. Based on the stress-strain analysis, the SiC crystal has shown the elastic deformation characteristics at the low temperature region. But the slight plastic deformation behavior was shown as applied the high strain over $1,000^{\circ}C$. Also the elastic constants of the SiC crystal were changed from about 475 GPa to 425 GPa as increased the temperature to $1,250^{\circ}C$.

Non-clinical Trials using 14C-Acetaminophen to Validate Biomedical Accelerator Mass Spectrometry System (14C-아세트아미노펜 비임상시험을 통한 생체시료 분석용 가속질량분석기의 검증)

  • Jinho Song;Jae Hoon Shim;Jung Bae Park;Chang Su Yeo;Soo Hyeon Bae;Min Sun Choi;Mi Hye Kwon;Kyeong Min Kim
    • Journal of Radiation Industry
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    • v.17 no.2
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    • pp.127-134
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    • 2023
  • Pharmacokinetic (PK) data provide pivotal information in drug development, and they are usually first studied in the preclinical stage using various animals. However, quite often, animal PK data may not match with human PK, especially in metabolites. Thus, most regulatory agencies in the world make it mandatory to obtain metabolite information using 14C radiolabeled drug in human for small molecule drug candidates. However, such studies are expensive and time consuming and they are usually done at the end of Phase II trials using ~3.7 MBq of 14C labeled drug in a limited number of human subjects. Introduction of accelerator mass spectrometry (AMS) in this kind of study has revolutionized it. Since AMS can measure 14C level as close as natural abundance, it can quantify the amounts of 14C labeled drugs and their metabolites produced in human body that consumes less than the amount of 0.0037 MBq of 14C labeled drug, a very safe level of radioactive dose in human. Therefore, it is now possible to conduct human 14C studies safely in early clinical trials without spending hefty amount of money and time. Korea Radioisotope Center for Pharmaceuticals(KRICP) at Korea Institute of Biological and Medical Sciences(KIRAMS) has established an AMS facility in 2018, housing a 0.5MV AMS manufactured at the US National Electrostatics Corps (NEC). The AMS instrument has been validated using various standard samples that have been prepared at Lawrence Livermore National Laboratory in the US, a worldly reputable provider of AMS standards. In this paper, we present a mass balance study for acetaminophen in rats using AMS and prove that the study results are equivalent with those of literature, which shows the AMS facilities at KRICP has successfully installed and be ready to be used in the various PK studies using 14C labelled compounds for new drug development.

New Inorganic Vertical Alignment Material Suitable for Large Area LCD Panel

  • Rho, Soon-Joon;Hiroyuki, Kamiya;Jeon, Baek-Kyun;Kim, Kyeong-Hyeon
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07a
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    • pp.330-333
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    • 2005
  • We investigated the liquid crystal (LC) alignment phenomena using a-C:H and a-C:F:H thin films. Homogeneous alignment is obtained using ion beam treated hydrogenated amorphous carbon (a-C:H) thin films. Homeotropic alignment is obtained using F treated a-C:H thin films, namely, fluorinated amorphous carbon (a-C:F:H) thin films. We investigated the relationship between the surface properties of amorphous carbon based alignment layer and LC alignment phenomena.

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