• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1208-1211
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• 2003

High quality $Bi_2Sr_2Ca_nCu_{n+1}O_x$ superconducting thin films fabricated by using the evaporation method at various substrate temperatures, $T_{sub}$, and ozone gas pressures, $pO_3$. The correlation diagrams of the $Bi_2Sr_2Ca_nCu_{n+1}O_x$ phases with $T_{sub}$ and $pO_3$ are established in the 2212 and 2223 compositional films. In spite of 2212 compositional sputtering, Bi2201 and Bi2223 as well as Bi2212 phases come out as stable phases depending on $T_{sub}$ and $pO_3$. From these results, the thermodynamic evaluation of ${\Delta}H$ and ${\Delta}S$, which are related with Gibbs' free energy change for single Bi2212 or Bi2223 phase, was performed.

• Journal of Environmental Health Sciences
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• v.31 no.5 s.86
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• pp.423-430
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• 2005

This research was performed to evaluate the effectiveness of one- and dual-stage recycled-water systems in slurry bioreactor treatment for coal tar-contaminated soil. Silty loam soil was used for this research. Coal tar and 14 target PAHs (Polycyclic Aromatic Hydrocarbons) concentration in the soil were determined with gas chromatography. There was no significant difference between removal efficiencies of one- and dual-stage recycled water systems in case of about 4,000 mg coar tar/kg. However, the dual-stage system increased significantly the removal efficiency in case of about 20,000 mg coar tar/kg and the first-order kinetic constant of the system was over 1.5 times higher than that of one-stage recycled water system. 3-Ring compounds in PAHs was removed completely within 30 days of operation. Coar tar was removed in over 96% through biodegradation and removed in about 4% by evaporation. High correlation coefficient($r^2=0.91$) was found between water solubility and removal efficiency of the cyclic compounds.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.194-195
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• 2005

(100-x)Zn xMg alloy films are prepared onto cold-rolled steel substrates; where x ranged from 0 to about 38 atomic %. The alloy films show microcrystalline and grain structures respectively, according to preparation conditions such as composition ratio of zinc and magnesium or gas pressures etc.. And X-ray diffraction analysis indicates not only the presence of Zn-Mg thin films with forced solid solution but also the one of $MgZn_2$ alloy films partly. In addition the influence of Mg/Zn composition ratio and morphology of the Zn-Mg alloy films on corrosion behavior is evaluated by electro-chemical anodic polarization tests in deaerated 3% NaCl solution. From this experimental results, all the prepared Zn-Mg alloy films showed obviously good corrosion resistance to compare with 99.99% Zn and 99.99% Mg Ingots for evaporation metal. It is thought that the Zn-Mg films with effective forced solid solution prepared by plasma enhanced PVD method, produces smaller and denser grain structure so that may improve the formation of homogeneous passive layer in corrosion environment.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.11
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• pp.1627-1633
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• 2012

This study was to evaluate the feasibility of recycling the solids separated from swine wastewater treatment process as a fuel source for heat production and to provide a data set on the gas emissions and combustion properties. Also, in this study, the heavy metals in ash content were analyzed for its possible use as a fertilizer. Proximate analysis of the solid recovered from the swine wastewater after flocculation with organic polymer showed high calorific (5,330.50 kcal/kg) and low moisture (15.38%) content, indicating that the solid separated from swine wastewater can be used as an alternative fuel source. CO and NOx emissions were found to increase with increasing temperature. Combustion efficiency of the solids was found to be stable (95 to 98%) with varied temperatures. Thermogravimetry (TG) and differential thermal analysis (DTA) showed five thermal effects (four exothermic and one endothermic), and these effects were distinguished in three stages, water evaporation, heterogeneous combustion of hydrocarbons and decomposition reaction. Based on the calorific value and combustion stability results, solid separated from swine manure can be used as an alternative source of fuel, however further research is still warranted regarding regulation of CO and NOx emissions. Furthermore, the heavy metal content in ash was below the legal limits required for its usage as fertilizer.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1869-1873
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• 2008

In this work, to make it possible to generate glow discharge in atmospheric pressure condition with relatively high and wide electric field, micro channel reactor is proposed. Si DRIE and Cr deposition by Ebeam evaporation is used to make channel and bottom electrode layer. Upper electrode is made from ITO glass to visualize discharge within micro channel. Fabricated reactor is verified by generating uniform glow plasma with N2 / He gases each as working fluid. The range of gas electric field to generate glow plasma is from about 200 V/cm and upper limit is not observed in tested condition of up to 150 kV/cm. This data shows that micro channel plasma reactor is more versatile. Indirect estimation of electron temperature in this reactor can be inferred that the electron temperature within glow discharge in micro reactor lies $0{\sim}2eV$. This research demonstrates that the reactor is appropriate in application that needs to maintain low temperature condition during chemical process.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.127-132
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• 2003

A study of high-pressure n-heptane droplet vaporization is conducted with emphasis placed on equilibrium at vapor-liquid interface. General frame of previous rigorous model[1] is retained but tailored for flash equilibrium calculation of vapor-liquid interfacial thermodynamics. The model is based on complete time-dependent conservation equations with a full account of variable properties and vapor-liquid interfacial thermodynamics. The influences of high-pressure phenomena, including ambient gas solubility, thermodynamic non-ideality, and property variation on the droplet evaporation are investigated. The governing equations and associated moving interfacial boundary conditions are solved numerically using a implicit scheme with the preconditioning method and the dual time integration technique. And a parametric study of entire droplet vaporization history as a function of ambient pressure, temperature has been conducted. Some computational results are compared with Sato's experimental data for the validation of calculations. For low ambient temperatures, the droplet lifetime first increases with pressures, then decreases for high pressures. For higher ambient temperatures, the droplet lifetime increase with less amplitude than that of low ambient temperatures, which then decreases with more amplitude than that of low temperatures. The solubility of nitrogen can not be neglected in the high pressure and it becomes higher as the pressure goes up.

• Journal of ILASS-Korea
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• v.21 no.1
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• pp.47-52
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• 2016

This paper describes the modeling of CNG direct injection using gaseous sphere injection model. Simulation of CNG direct injection does not need break up and evaporation model compared to that of liquid fuel injection. And very fine mesh is needed near the injector nozzle to resolve the inflow boundary. Therefore it takes long computation time for gaseous fuel injection simulation. However, simulation of CNG direct injection could be performed with the coarse mesh using gaseous sphere injection model. This model was integrated in KIVA-3V code and RNG $k-{\varepsilon}$ turbulence model needs to be modified because this model tends to over-predict gas jet diffusion. Furthermore, we preformed experiments of gaseous fuel injection using PLIF (planar laser induced fluorescence)method. Gaseous fuel injection model was validated against experiment data. The simulation results agreed well with the experiment results. Therefore gaseous sphere injection model has the reliability about gaseous fuel direct injection. And this model was predicted well a general tendency of gaseous fuel injection.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.196-197
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• 2010

NAND형 charge trap flash (CTF) non-volatile memory (NVM) 소자가 30nm node 이하로 고집적화 되면서, 기존의 SONOS형 CTF NVM의 tunnel barrier로 쓰이는 SiO2는 direct tunneling과 stress induced leakage current (SILC)등의 효과로 인해 data retention의 감소 등 물리적인 한계에 이르렀다. 이에 따라 개선된 retention과 빠른 쓰기/지우기 속도를 만족시키기 위해서 tunnel barrier engineering (TBE)가 제안되었다. TBE NVM은 tunnel layer의 전위장벽을 엔지니어드함으로써 낮은 전압에서 전계의 민감도를 향상 시켜 동일한 두께의 단일 SiO2 터널베리어 보다 빠른 쓰기/지우기 속도를 확보할 수 있다. 또한 최근에 각광받는 high-k 물질을 TBE NVM에 적용시키는 연구가 활발히 진행 중이다. 본 연구에서는 Si3N4와 HfAlO (HfO2 : Al2O3 = 1:3)을 적층시켜 staggered의 새로운 구조의 tunnel barrier Capacitor를 제작하여 전기적 특성을 후속 열처리 온도와 방법에 따라 평가하였다. 실험은 n-type Si (100) wafer를 RCA 클리닝 실시한 후 Low pressure chemical vapor deposition (LPCVD)를 이용하여 Si3N4 3 nm 증착 후, Atomic layer deposition (ALD)를 이용하여 HfAlO를 3 nm 증착하였다. 게이트 전극은 e-beam evaporation을 이용하여 Al를 150 nm 증착하였다. 후속 열처리는 수소가 2% 함유된 질소 분위기에서 $300^{\circ}C$와 $450^{\circ}C$에서 Forming gas annealing (FGA) 실시하였고 질소 분위기에서 $600^{\circ}C{\sim}1000^{\circ}C$까지 Rapid thermal annealing (RTA)을 각각 실시하였다. 전기적 특성 분석은 후속 열처리 공정의 온도와 열처리 방법에 따라 Current-voltage와 Capacitance-voltage 특성을 조사하였다.

• Journal of environmental and Sanitary engineering
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• v.13 no.3
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• pp.19-29
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• 1998

The calcination reactivity of limestone and physical property changes of calcined lime were investigated with a temperature($720~1000^{\circ}C$ under atmospheric gas($N_2$, $CO_2$) conditions. The mechanisms of mass transport in a lime matrix were represented by the evaporation and condensation (${\gamma}=1.7$) at $1000^{\circ}C$ and the volume diffusion (${\gamma}=2.7$) at $800^{\circ}C$, which was obtained by the specific surface area of calcined lime with sintering conditions. Also, the effect of physical property on the reactivity of sulfation reaction was determined by the changes of pore size with $lime-SO_2$ reaction in this work. The initial sulfation rate of calcined lime increased with increasing temperature, whereas the capture capacity of $SO_2$ exhibited a maximum value at $900^{\circ}C$. The pore volume of sulfated lime was decreased with increasing sulfation time, but the major pores shifted to the distribution of larger size at a temperature of $850{\;}~{\;}1000^{\circ}C$. The mean pore size of sulfated lime based on pore volume decreased gradually at $1000^{\circ}C$; however, it increased with sulfation time up to 40 min and rapidly decreased thereafter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.47-50
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• 2002

ZnO nanowires were coated conformally with aluminum oxide ($Al_{2}O_{3}$) material by atomic layer deposition (ALD). The ZnO nanowires were first synthesized on a Si (100) substrate at $1380^{\circ}C$ from ball-milled ZnO powders by a thermal evaporation procedure with an argon carrier gas without any catalysts; the length and diameter of these ZnO nanowires are $20\sim30{\mu}m$ and $50{\sim}200$ nm, respectively. $Al_{2}O_{3}$ films were then deposited on these ZnO nanowires by ALD at a substrate temperature of $300^{\circ}C$ using trimethylaluminum (TMA) and distilled water ($H_{2}O$). Transmission electron microscopy (TEM) images of the deposited ZnO nanowires revealed that 40nm-thick $Al_{2}O_{3}$ cylindrical shells surround the ZnO nanowires.