• 제목/요약/키워드: Atomic parameters

검색결과 841건 처리시간 0.028초

Development of High Entropy Alloy Film using Magnetron Sputtering

  • Kim, Young Seok;Lim, Ki Seong;Kim, Ki Buem
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 한국표면공학회 2018년도 춘계학술대회 논문집
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    • pp.129-129
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    • 2018
  • Hard coating application is effective way of cutting tool for hard-to-machine materials such as Inconel, Ti and composite materials focused on high-tech industries which are widely employed in aerospace, automobile and the medical device industry also Information Technology. In cutting tool for hard-to-machine materials, high hardness is one of necessary condition along with high temperature stability and wear resistance. In recent years, high-entropy alloys (HEAs) which consist of five or more principal elements having an equi-atomic percentage were reported by Yeh. The main features of novel HEAs reveal thermodynamically stable, high strength, corrosion resistance and wear resistance by four characteristic features called high entropy, sluggish diffusion, several-lattice distortion and cocktail effect. It can be possible to significantly extend the field of application such as cutting tool for difficult-to-machine materials in extreme conditions. Base on this understanding, surface coatings using HEAs more recently have been developed with considerable interest due to their useful properties such as high hardness and phase transformation stability of high temperature. In present study, the nanocomposite coating layers with high hardness on WC substrate are investigated using high entropy alloy target made a powder metallurgy. Among the many surface coating methods, reactive magnetron sputtering is considered to be a proper process because of homogeneity of microstructure, improvement of productivity and simplicity of independent control for several critical deposition parameters. The N2 is applied to reactive gas to make nitride system with transition metals which is much harder than only alloy systems. The acceleration voltage from 100W to 300W is controlled by direct current power with various deposition times. The coating layers are systemically investigated by structural identification (XRD), evaluation of microstructure (FE-SEM, TEM) and mechanical properties (Nano-indenter).

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Ingestion Dose Evaluation of Korean Based on Dynamic Model in a Severe Accident

  • Kwon, Dahye;Hwang, Won-Tae;Jae, Moosung
    • Journal of Radiation Protection and Research
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    • 제43권2호
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    • pp.50-58
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    • 2018
  • Background: In terms of the Level 3 probabilistic safety assessment (Level 3 PSA), ingestion of food that had been exposed to radioactive materials is important to assess the intermediate- and long-term radiological dose. Because the ingestion dose is considerably dependent upon the agricultural and dietary characteristics of each country, the reliability of the assessment results may become diminished if the characteristics of a foreign country are considered. Thus, this study intends to evaluate and analyze the ingestion dose of Korean during a severe accident by completely considering the available agricultural and dietary characteristics in Korea. Materials and Methods: This study uses COMIDA2, which is a program based on dynamic food chain model. It sets the parameters that are appropriate to Korean characteristics so that we can evaluate the inherent ingestion dose of Korean. The results were analyzed by considering the accident date and food category with regard to the $^{137}Cs$. Results and Discussion: The dose and contribution of the food category depicted distinctive differences based on the accident date. Particularly, the ingestion dose during the first and second years depicted a considerable difference by the accident date. However, after the third year, the effect of foliar absorption was negligible and exhibited a similar tendency along with the order of root uptake rate based on the food category. Conclusion: In this study, the agricultural and dietary characteristics of Korea were analyzed and evaluated the ingestion dose of Korean during a severe accident using COMIDA2. By considering the inherent characteristics of Korean, it can be determined that the results of this study will significantly contribute to the reliability of the Level 3 PSA.

Molecular Modeling Study on Morphine Derivatives Using Density Functional Methods and Molecular Descriptors (범밀도 함수법과 Molecular Descriptor를 이용한 모르핀 유도체에 대한 분자 모델링 연구)

  • Cotua, Jose;Cotes, Sandra;Castro, Pedro;Castro, Fernando;Mora, Liadys
    • Journal of the Korean Chemical Society
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    • 제54권4호
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    • pp.363-373
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    • 2010
  • Computational studies were carried out on the opiates morphine, heroin, codeine, pentazocine, and buprenorphine, under the density functional theory. The geometric parameters of the pharmacophore and substituents were evaluated at the B3LYP/6-31+G(d) level of theory. The electronic structure calculations were performed using the same hybrid functional at the B3LYP/6-311++G (d,p) level of theory. The atomic charges were obtained by Mulliken population analysis. Given the reported biological activity, calculated partition coefficients, and electronic and geometric analysis, pentazocine and buprenorphine were chosen as models for proposed analogues. These analogues were then studied and compared with the model molecules. The study reveals that the geometry and electronic structure of the pharmacophore remains consistent in the presence of different substituents. Because the proposed analogues preserve the studied properties of the model molecules, it is likely that these analogues display biological activity.

A Solid-Contact Indium(III) Sensor based on a Thiosulfinate Ionophore Derived from Omeprazole

  • Abbas, Mohammad Nooredeen;Amer, Hend Samy
    • Bulletin of the Korean Chemical Society
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    • 제34권4호
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    • pp.1153-1159
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    • 2013
  • A novel solid-contact indium(III)-selective sensor based on bis-(1H-benzimidazole-5-methoxy-2-[(4-methoxy-3, 5-dimethyl-1-pyridinyl) 2-methyl]) thiosulfinate, known as an omeprazole dimer (OD) and a neutral ionophore, was constructed, and its performance characteristics were evaluated. The sensor was prepared by applying a membrane cocktail containing the ionophore to a graphite rod pre-coated with polyethylene dioxythiophene (PEDOT) conducting polymer as the ion-to-electron transducer. The membrane contained 3.6% OD, 2.3% oleic acid (OA) and 62% dioctyl phthalate (DOP) as the solvent mediator in PVC and produced a good potentiometric response to indium(III) ions with a Nernstian slope of 19.09 mV/decade. The constructed sensor possessed a linear concentration range from $3{\times}10^{-7}$ to $1{\times}10^{-2}$ M and a lower detection limit (LDL) of $1{\times}10^{-7}$ M indium(III) over a pH range of 4.0-7.0. It also displayed a fast response time and good selectivity for indium(III) over several other ions. The sensor can be used for longer than three months without any considerable divergence in potential. The sensor was utilized for direct and flow injection potentiometric (FIP) determination of indium(III) in alloys. The parameters that control the flow injection method were optimized. Indium(III) was quantitatively recovered, and the results agreed with those obtained using atomic absorption spectrophotometry, as confirmed by the f and t values. The sensor was also utilized as an indicator electrode for the potentiometric titration of fluoride in the presence of chloride, bromide, iodide and thiocyanate ions using indium(III) nitrate as the titrant.

Corrosion Evaluation for Advanced Fuel Cycle Facilities (선진 핵연료주기 시설(AFC)의 부식건전성 조사, 분석)

  • Hwang, Seong Sik
    • Corrosion Science and Technology
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    • 제11권6호
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    • pp.213-217
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    • 2012
  • The amount of spent fuel from nuclear power plants has been increasing. An effective management plan of the spent fuel becomes a critical issue, because the storage capacity of each plant will reach its storage limit in a few years. The volume of high toxic spent fuel can be reduced through a fuel processing. Advanced Fuel Cycle (AFC) system is considered to be one of the options to reduce the toxicity and volume of the spent fuel. It is necessary to set up a test facility to demonstrate the feasibility of the process at the engineering scale. The objective of the work is a development of the safety evaluation technology for the AFC system. The evaluation technology of the AFC structural integrity and processes were surveyed and reviewed. Key evaluation parameters for the main processes such as electrolytic reduction, electrorefining, and electrowinning were obtained. The survey results may be used for the establishment of the AFC regulatory licensing procedure. The establishment of the licensing criteria minimizes the trials and errors of the AFC facility design. Issues taken from the survey on the regulatory procedure and design safety features for the AFC facility provide a chance to resolve potential issues in advance.

Adsorption Characteristics of Elemental Iodine and Methyl Iodide on Base and TEDA Impregnated Carbon (활성탄을 이용한 원소요오드 및 유기요오드 흡착특성)

  • Lee, Hoo-Kun;Park, Geun-Il
    • Nuclear Engineering and Technology
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    • 제28권1호
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    • pp.44-55
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    • 1996
  • For the purpose of controlling the release of radioiodine to the environment in nuclear power plants, adsorption characteristics of elemental iodine and methyl iodide on the base carbon and 2%, 5% TEDA impregnated carbons were studied. The amounts of adsorption of elemental iodine and methyl iodide on the carbons were compared with Langmuir, Freundlich, Sips and Dubinin-Astakhov(DA) isotherm equations. Adsorption data were well correlated by the DA equation based on the potential theory. Adsorption energy distributions were obtained from the parameters of the DA equation derived from the condensation approach method. For the adsorption of methyl iodide and elemental iodine-carbon system, the DA equation can be well expressed by the degree of heterogeneity of the micropore system because the surface is nonuniform when its potential energy is unequal. The adsorption energy distribution wes investigated to find a surface heterogeneity on the carbon. The surface heterogeneity for iodine-carbon system is highly affected by the adsorbate-adsorbent interaction as well as the pore structure. The surface heterogeneity increases as a content of TEDA impregnated increases. The adsorption nature of methyl iodide on carbon turned out to be more heterogeneous than that of elemental iodine.

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Spacer Grid Effects on Turbulent Flow in Rod Bundles (지지격자가 봉다발 난류유동에 미치는 영향)

  • Yang, Sun-Kyu;Chung, Moon-Ki
    • Nuclear Engineering and Technology
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    • 제28권1호
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    • pp.56-71
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    • 1996
  • The local hydrulic characteristics in subchannels of 5$\times$5 nuclear fuel bundles with spacer grids were measured at upstream and downstream of the spacer grid for the investigation of the spacer grid effects on turbulent flow structure by using an LDV(Laser Doppler Velocimeter). The measured parameters are axial velocity and turbulent intensity, skewness factor, and flatness factor. Pressure drops were also measured to evaluate the loss coefficient for the spacer grid and the friction factor for rod bundles. From these data, it was found that the turbulent mixing and forced mixing occur up to $x/D^h=10$ and 20 from the spacer grid, respectively. The turbulence decay behind spacer grid behaves in the similar decay rate as turbulent flow through mesh grids or screens. Mixing factors useful in subchannel analysis code were correlated from the data and show the highest value near spacer grid and then have a stable values.

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Effects of Plasma Surface Treatments Using Dielectric Barrier Discharge to Improve Diamond Films

  • Kang, In-Je;Ko, Min-Guk;Rai, Suresh;Yang, Jong-Keun;Lee, Heon-Ju
    • Proceedings of the Korean Vacuum Society Conference
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    • 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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    • pp.552-552
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    • 2013
  • In our study we consider Al2O3 ceramic substrates for Plasma Surface Treatments in order to improve deposited diamond surface and increase diamond deposition rate by applying DBD (Dielectric Barrier Dischrge) system. Because Plasma Surface Treatments was used as a modification method of material surface properties like surface free energy, wettability, and adhesion. By applying Plasma Surface Treatments diamond films are deposited on the Al2O3 ceramic substrates. DC Arc Plasmatron with mathane and hydrogen gases is used. Deposited diamond films are investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) is studied. As a result, nanocrystalline diamond films were identified by using SEM and diamond properties in XRD peaks at (111, $43.8{\Box}$, (220, $75.3{\Box}$ and (311, $90.4{\Box}$ were shown. Absorption peaks in FTIR spectrum, caused by CHx sp3 bond stretching of CVD diamond films, were identified as well. Finally, we improved such parameters as depostion rate ($2.3{\mu}m$/h), diamond surface uniformity, and impurities level by applying Plasma Surface Treatments. These experimental results show the importance of Plasma Surface Treatments for diamond deposition by a plasma source.

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Study on the Determination of Fatigue Damage Parameter for Rubber Component under Multiaxial Loading (다축하중이 작용하는 방진고무부품 피로손상 파라미터 결정에 관한 연구)

  • Moon, Seong-In;Woo, Chang-Su;Kim, Wan-Doo
    • Elastomers and Composites
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    • 제47권3호
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    • pp.194-200
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    • 2012
  • Rubber components have been widely used in automotive industry as anti-vibration components for many years. These subjected to fluctuating loads, often fail due to the nucleation and growth of defects or cracks. To prevent such failures, it is necessary to understand the fatigue failure mechanism for rubber materials and to evaluate the fatigue life for rubber components. The objective of this study is to develop the durability analysis process for vulcanized rubber components, which is applicable to predict fatigue life at initial product design step. The determination method of nonlinear material constants for FE analysis was proposed. In order to investigate the applicability of the commonly used damage parameters, fatigue tests and corresponding finite element analyses were carried out and strain energy density was proposed as the fatigue damage parameter for rubber components. The fatigue analysis for automotive rubber components was performed and the durability analysis process was reviewed.

Polarization of Rayleigh Scattered Lyα in Active Galactic Nuclei

  • Chang, Seok-Jun;Lee, Hee-Won;Yang, Yujin
    • The Bulletin of The Korean Astronomical Society
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    • 제41권1호
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    • pp.70.3-70.3
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    • 2016
  • Active galactic nuclei (AGNs) typically show a non-thermal continuum locally represented by a power-law and many prominent emission lines in the UV and optical regions. AGNs are classified by two types, where Type I AGNs exhibit both broad and narrow lines and only narrow lines are observed in Type 2 AGNs. The unification models of AGNs invoke the existence of a molecular torus just outside of the broad line region. In the presence of a high column HI region associated with the molecular torus, we propose that significant fraction of broad line photons near Lyman series can be scattered by atomic hydrogen in the torus. In particular, $Ly{\alpha}$ being the strongest emission line, strong linear polarization may develop around $Ly{\alpha}$ through Rayleigh scattering. We adopt a Monte Carlo technique to investigate the polarized transfer of $Ly{\alpha}$ in a thick HI region with the shape of a torus. We consider the range of HI column density N_HI = 1020-23 with fixed geometric parameters of the torus such as the inner and outer radii and the height. We present the polarized spectra and angular distribution of Rayleigh scattered radiation around $Ly{\alpha}$. We find that the $Ly{\alpha}$ core part is polarized in the direction perpendicular to the symmetry axis whereas in the far wing part it is polarized in the parallel direction. It is concluded that the unification of AGNs implies that $Ly{\alpha}$ can be uniquely polarized through Rayleigh scattering.

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