• Title, Summary, Keyword: equilibrium process

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Characteristics of Rotating arc Plasma in $CH_4$ Reforming (메탄 개질에서의 회전 아크 플라즈마 특성)

  • Lee, Dae-Hoon;Kim, Kwan-Tae;Cha, Min-Suk;Song, Young-Hoon;Kim, Dong-Hyun
    • 한국연소학회:학술대회논문집
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    • pp.144-148
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    • 2006
  • Characteristics of a plasma reactor for partial oxidation of methane, especially focused on the role and effectiveness of plasma chemistry, is investigated. Partial oxidation of methane is investigated using a rotating arc which is a three dimensional version of a typical glidingarc. The rotating arc has both the characteristics of equilibrium and non-equilibrium plasma. Non-equilibrium characteristics of the rotating gliding arc can be increased by rotating an elongated arc string attached at both the tip of inner electrode and the edge of outer electrode. In this way, plasma chemistry can be enhanced and hydrogen selectivity can reach almost 100% that is much higher than thermal equilibrium condition. As a result, the present study enables the strategic approach of the plasma reforming process by means of appropriate reactor design to maximize plasma effect and resulting in maximized reaction efficiency.

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A Study of the Ionization Characteristics of Xenon Gas by Shock Compression (충격 압축에 의한 제논 가스의 이온화 특성 연구)

  • Lee, D.S.;Shin, J.R.;Choi, J.Y.;Choi, Y.S.;Kim, H.W.
    • Journal of the Korea Institute of Military Science and Technology
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    • v.13 no.3
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    • pp.493-502
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    • 2010
  • In this paper, the ionization characteristics of noble gases are studied numerically behind strong shock waves. As a first step, the equilibrium ionization mechanism of noble gases is modeled in wide ranges of temperature and pressure. As a next step the equilibrium ionization model is coupled with fluid dynamic equations to analyze the local thermodynamic equilibrium(LTE) ionization process at high temperature and pressure conditions behind the strong imploding shock waves. The ionization characteristics of xenon gas is studied in a wide range of test conditions with thermal radiation effects. Hence, the results give optimal conditions of maximum ionization and radiation behind the imploding shock waves.

An Analytical Approach for Structural Synthesis of Substructures

  • Eun, Hee-Chang;Park, Sang-Yeol;Lee, Eun-Taik
    • Journal of Mechanical Science and Technology
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    • v.18 no.9
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    • pp.1529-1536
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    • 2004
  • A structure is broken down into a number of substructures by means of the finite element method and the substructures are synthesized for the complete structure. The divided substructures take two types: fixed-free and free-free elements. The flexibility and stiffness matrices of the free-free elements are the Moore-Penrose inverse of each other. Thus, it is not easy to determine the equilibrium equations of the complete structure composed of two mixed types of substructures. This study provides the general form of equilibrium equation of the entire structure through the process of assembling the equilibrium equations of substructures with end conditions of mixed types. Applications demonstrate that the proposed method is effective in the structural analysis of geometrically complicated structures.

Dynamics of Vaccination Model with Holling Type II Functional Response

  • Bhatia, Sumit Kaur;Chauhan, Sudipa;Nasir, Umama
    • Kyungpook Mathematical Journal
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    • v.60 no.2
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    • pp.319-334
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    • 2020
  • We propose a mathematical model with Holling type II functional response, to study the dynamics of vaccination. In order to make our model more realistic, we have incorporated the recruitment of infected individuals as a continuous process. We have assumed that vaccination cannot be perfect and there is always a possibility of re-infection. We have obtained the existence of a disease free and endemic equilibrium point, when the recruitment of infective is not considered and also obtained the existence of at least one endemic equilibrium point when recruitment of infective is considered. We have proved that if Rv < 1, disease free equilibrium is locally asymptotically stable, which leads to the elimination of the disease from the population. The persistence of the model has also been established. Numerical simulations have been done to establish the results obtained.

Solid State Cesium Ion Beam Sputter Deposition

  • Baik, Hong-Koo
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • pp.5-18
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    • 1996
  • The solid state cesium ion source os alumino-silicate based zeolite which contains cerium. The material is an ionic conductor. Cesiums are stably stored in the material and one can extract the cesiums by applying electric field across the electrolyte. Cesium ion bombardment has the unique property of producing high negative ion yield. This ion source is used as the primary source for the production of a negative ion without any gas discharge or the need for a carrier gas. The deposition of materials as an ionic species in the energy range of 1.0 to 300eV is recently recognized as a very promising new thin film technique. This energetic non-thermal equilibrium deposition process produces films by “Kinetic Bonding / Energetic Condensation" mechansim not governed by the common place thermo-mechanical reaction. Under these highly non-equilibrium conditions meta-stable materials are realized and the negative ion is considered to be an optimum paeticle or tool for the purpose. This process differs fundamentally from the conventional ion beam assisted deposition (IBAD) technique such that the ion beam energy transfer to the deposition process is directly coupled the process. Since cesium ion beam sputter deposition process is forming materials with high kinetic energy of metal ion beams, the process provider following unique advantages:(1) to synthesize non thermal-equilibrium materials, (2) to form materials at lower processing temperature than used for conventional chemical of physical vapor deposition, (3) to deposit very uniform, dense, and good adhesive films (4) to make higher doposition rate, (5) to control the ion flux and ion energy independently. Solid state cesium ion beam sputter deposition system has been developed. This source is capable of producing variety of metal ion beams such as C, Si, W, Ta, Mo, Al, Au, Ag, Cr etc. Using this deposition system, several researches have been performed. (1) To produce superior quality amorphous diamond films (2) to produce carbon nitirde hard coatings(Carbon nitride is a new material whose hardness is comparable to the diamond and also has a very high thermal stability.) (3) to produce cesiated amorphous diamond thin film coated Si surface exhibiting negative electron affinity characteristics. In this presentation, the principles of solid state cesium ion beam sputter deposition and several applications of negative metal ion source will be introduced.

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Calculation of Mass-Heat Balance on the Iodine Crystallizer for SI Thermochemical Hydrogen Production Process (SI 열화학 수소 생산 공정 요오드 결정화기 열-물질 수지 계산)

  • Lee, Pyoung Jong;Park, Byung Heung
    • Journal of Institute of Convergence Technology
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    • v.5 no.1
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    • pp.1-5
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    • 2015
  • SI thermochemical hydrogen production process achieves water splitting into hydrogen and oxygen through three chemical reactions. The process is comprised of three sections and one of them is HI decomposition into $H_2$ and $I_2$ called as Section III. The production of $H_2$ included processes involving EED for concentrating a product stream from Section I. Additionally an $I_2$ crystallization would be considered to reduce burden on EED by removing certain amount of $I_2$ out of a process stream prior to EED. In this study, the current thermodynamic model of SI process was briefly described and the calculation results of the applied Electrolytes NRTL model for phase equilibrium calculations was illustrated for ternary systems of Section III. We calculated temperature and heat duty of an $I_2$ crystallizer and heat duty of heaters using UVa model and heat balance equation of simulation tool. The results were expected to be used as operation information in optimizing HI decomposition process and setting up material balance throughout SI process.

A New Aluminium Container for $\gamma$-Ray Spectrometry Analysis of Radium and Radon (라듐 및 라돈의 감마선 분광 분석을 위한 알루미늄 용기의 제작 및 특성 조사)

  • Lee, Kil Yong;Yoon, Yoon Yeol;Seo, Bum Kyoung
    • Analytical Science and Technology
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    • v.13 no.6
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    • pp.743-750
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    • 2000
  • For the ${\gamma}$-ray spectrometry analysis of radium and radon in environmental samples, plastic Marinelli beakers have been usually used. But, there are two problems; one is the increment of background by adsorption of airborne radon daughters on the plastic beaker, and other is the incompleteness of radioactive equilibrium by the loss of gaseous radon produced during the radioactive equilibrium process. In order to solve these problems, we made aluminium counting container, and investigated its characteristics. We investigated radioactive equilibrium process using the aluminium container. We found that both solid and liquid samples reached at radioactive equilibrium state in the aluminium container without loss of gaseous radon. By the use of the aluminium container, we established radon and radium analysis method of solid and liquid samples using gamma-ray spectrometry.

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Experiment and Simulation of PSA Process for $H_2/Ar$ Mixtures gas ($H_2/Ar$ 혼합기체의 PSA 공정 실험과 모사)

  • Kang, Seok-Hyun;Jeong, Byung-Man;Choi, Hyun-Woo;Kim, Sung-Hyun;Lee, Byung-Kwon;Choi, Dae-Ki
    • Transactions of the Korean hydrogen and new energy society
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    • v.16 no.2
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    • pp.180-190
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    • 2005
  • The PSA cycle was performed for the separation of binary gas mixture $H_2/Ar$ (80%/20%) using the six-step two-bed process. Adsorption equilibrium contains a LRC model for equilibrium adsorption isotherms and a LDF model for mass transfer. Aspen ADSIM, simulator was applied to predict the separation performance. The effect of cycle parameters such as feed rate, adsorption pressure and P/F ratio on the separation of hydrogen has been studied in experiment and simulation. In the results, maximize the recovery of hydrogen as a high purity was 13LPM feed flowrate, 120sec adsorption time, 11atm adsorption pressure and 0.1 P/F ratio in a cyclic steady-state come out since 10th cycle.

Removal Characteristics of Lead by Immobilizing Agents and Immobilized Seaweed (고정화제와 고정화된 해조류에 의한 납의 제거 특성)

  • 이학성;서정호;서근학
    • Journal of Environmental Health Sciences
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    • v.27 no.1
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    • pp.83-87
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    • 2001
  • In this study, the characteristics of lead removal by PVA and alginate bead which used widely as immobilizing agents were investigated, and the difference of removal amounts between pure PVA/alginate bead and Sargassum thunbergii immobilized bead was studied. All PVA beads, pure and S. thunbergii immobilized, reached an equilibrium state in about 1 hour, and S. thunbergii immobilized bead adsorbed more lead than pure one. But in the case of alginate beads, they needed much time, about 5 hours, to reach an equilibrium state, and adsorbed lead four times higher than PVA beads. Therefore, it was considered that alginate beads had more mass transfer resistance and function groups which adsorb lead such as hydroxyl, carboxyl and etc. than PVA bead. To examine the continuous usage of alginate beads, the process of adsorption/desorption of lead was conducted repeatedly. As the process proceeded, the amounts of lead adsorption decrease, so it was indicated that the non-desorbed lead from alginate bead at first adsorption/desorption process remained constantly.

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Ultrafine Grained Bulk Al Matrix Carbon Nanotube Composites Processed by High Pressure Torsion (고압비틀림 성형 공정에 의한 Al 기지 CNT 복합재료의 초미세결정 벌크화)

  • Joo,, S.H.;Kim, H.S.
    • Transactions of Materials Processing
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    • v.19 no.7
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    • pp.423-428
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    • 2010
  • Carbon nanotubes(CNTs) are expected to be ideal reinforcements of metal matrix composite materials used in aircraft and sports industries due to their high strength and low density. In this study, a high pressure torsion(HPT) process at an elevated temperature(473K) was employed to achieve both powder consolidation and grain refinement of aluminummatrix nanocomposites reinforced by 5vol% CNTs. CNT/Al nanocomposite powders were fabricated using a novel molecular-level mixing process to enhance the interface bonding between the CNTs and metal matrix before the HPT process. The HPT processed disks were composed of mostly equilibrium grain boundaries. The CNT-reinforced ultrafine grained microstructural features resulted in high strength and good ductility.