• 융복합기술연구소 논문집
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• 제2권2호
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• pp.30-34
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• 2012

The SI thermochemical cycle process accomplishes water splitting through distinctive three chemical reactions. We focused on thermodynamic models applicable to the process. Recently, remarkable models based on the assumed ionic species have been developed to describe highly nonideal behavior on the liquid phase reactions. ElecNRTL models with ionic reactions were proposed in order to provide reliable process simulation results for phase equilibrium calculations in Section II and III. In this study, the current thermodynamic models of SI thermochemical cycle process were briefly described and the calculation results of the applied ElecNRTL models for phase equilibrium calculations were illustrated for binary systems.

• International Journal of Automotive Technology
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• 제2권1호
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• pp.25-31
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• 2001

It is necessary to understand the combustion process and cycle-by-cycle variation in combustion to improve the engine stability and consequently to improve the fuel economy and exhaust emissions. The pressure related parameters instead of mass fraction burned were compared for the effect of initial combustion pressures on the following combustion and the analysis of cycle-by-cycle variation in combustion for two pen injected SI engines. The correlation between IMEP and pressures at referenced crank angles showed almost the same trends for equivalence ratios, but the different mixture preparations indicated different tendency. The dependency of IMEP on pressure at the referenced crank angles increases as the mixture becomes leaner for both engines. The mixture distribution in the combustion chamber was varied with the coolant temperature and intake valve deactivation due to the evaporation of fuel and air motion. The correlation between pressure related parameters were also compared for the coolant temperatures and air motion.

• Korean Chemical Engineering Research
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• 제52권4호
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• pp.459-466
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• 2014

열화학적인 수소 생산 공정 중 하나인 S-I Cycle은 요오드와 황을 이용한 수소 생산 공정으로써 물 분자로부터 수소 분자를 얻어내는 순환 공정이다. 수소 생산 공정에 열을 공급하고자 하는 초고온 원자로(VHTR; Very High Temperature Reactor)는 원자로에서 수소 생산 공정으로 방사능 없이 안전하게 열을 전달하기 위하여 중간열교환기(IHX; Intermediate Heat Exchanger)가 필요하다. 본 연구에서는 수소 생산공정과 초고온 원자로간의 중간 열교환 공정을 모사하여 운전압력 및 작동 유체의 변화에 따른 중간 열교환기의 효율을 계산하고 가장 경제적인 중간 열교환기를 설계하기 위한 공정 조건을 도출하였다.

• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.139-151
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• 2011

The sulfur-iodine (SI) thermochemical water splitting cycle is one of promising hydrogen production methods from water using high-temperature heat generated from a high temperature gas-cooled nuclear reactor (HTGR). The SI cycle consists of three main units, such as Bunsen reaction, HI decomposition, and $H_2SO_4$ decomposition. The feasibility of continuous operation of a series of subunits for $H_2SO_4$ decomposition was investigated with a bench-scale facility working at ambient pressure. It showed stable and reproducible $H_2SO_4$ decomposition by steadily producing $SO_2$ and $O_2$ corresponding to a capacity of 1 mol/h $H_2$ for 24 hrs.

• 한국응용과학기술학회지
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• 제32권4호
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• pp.718-723
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• 2015

For the fabrication of the Si negative electrode in Li-ion batteries (LIBs) containing the cross-linking polymer binder, in this work, the urethane acrylate (UA) oligomer was synthesized via a simple synthetic process. The cross-linked poly(urethane acrylate) (CPUA)/carbone black (CB)/Si composite (CPUA/CB/Si composite) was fabricated through reactions between their reactive vinyl segments in the UA oligomer. Interestingly, the CPUA/CB/Si composite showed better cycle performance than the poly(vinylidene fluoride) (PVdF)/CB/Si composite (PVdF/CB/Si composite) and the polyurethane (PU)/CB/Si composite (PU/CB/Si composite). The CPUA/CB/Si composite had the best lithiation of about $2586mAh\;g^{-1}$. The UA oligomer showed a good compatibility with the electrode materials and current collector after and before a curing process.

• 한국수소및신에너지학회논문집
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• 제22권3호
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• pp.340-348
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• 2011

Effects of various inorganic-metal oxide (Zr, Zn, Si, Al and Ca as promoters and stabilizers) additive on the reduction rate of iron oxide and the composition of forming hydrogen using the steam-iron cycle operation was investigated. The reduction rate of redox agent with additive was determined from weight change by TGA. The changes of weight loss and reduction rate according to redox agent with various additive affected the hydrogen purity and cycle stability of the process. The cyclic micro reactor showed that hydrogen purity exceeding 95% could be obtained by the water splitting with Si/Fe, Zn/Fe, Zr/Fe redox agents. The redox agents with these elements had an affect on redox cycle stability as a good stabilizer for forming hydrogen by the steam-iron process.

• 공학기술논문지
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• 제4권4호
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• pp.431-436
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• 2011

This study was carried out to reduce the problem during distillation process, which separate U, TRU (TRans Uranium) metal electro deposit, Cd and LiCl-KCl eutectic salt generating from LCC (Liquid Cadmium Cathode) electro winning process. The cadmium recovering apparatus was manufactured to separate for each metal using solid-liquid separation method. The apparatus consists of the first sieve for the separation of U and TRU metal electrodeposit, the second sieve for the separation of LiCl-KCl eutectic salt, cadmium collection basket, and a heating furnace. In addition, the size of each sieve is 2 mm to 3 mm. In this experiment, a metal wire was employed to replace TRU metal electrodeposit and U, which exist actually in a LCC crucible. In the solid state, The LiCl-KCl is separated at 340℃ at which the solid and the liquid of the remaining cadmium and LiCl-KCl eutectic salt coexists in each, after the metal wire separated at 500℃. As a result, it seems that it would be beneficial to set the processing condition in the distillation process with the additional treatment process of cadmium and LiCl-KCl eutectic salt.

• 대한기계학회논문집A
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• 제24권3호
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• pp.777-785
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• 2000

The low-cycle fatigue behaviors of cast AI-Si alloy and composite with reinforcement of SIC particles were compared with those of extruded unreinforced matrix alloy and composite in order to investigate the influence of cast and extrusion processes on the cyclic deformation and fatigue life. Generally, both cast and extruded composites including the unreinforced alloy exhibited cyclic hardening behaviour, with more pronounced strain-hardening for the composites with a higher volume fraction of the SiC particles. However, cast composite under a low applied cyclic strain showing no observable plastic strain exhibited cyclic softening behavior due to the cast porosities. The elastic modulus and yield strength of the cast composite were found to be quite comparable to those of the extruded composite, however, the extrusion process considerably improved the ductility and fracture strength of the composite by effectively eliminating the cast porosities. Low-cycle fatigue lives of the cast alloy and composite were shorter than those of the extruded counterparts. Large difference in life between cast and extruded composites was attributed to the higher influence of the cast porosities on the fatigue life of the composite than that of the unreinforced alloy material. A fatigue damage parameter using strain energy density effectively represented the inferior life in the low-cycle regime and superior life in the high-cycle regime for the composite, compared to the unreinforced alloy.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.279-286
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• 2020

In this article, we develop a reactive distillation (RD) column configuration for the production of hydrogen. This RD column is in the HI decomposition section of the sulphur - iodine (SI) thermochemical cycle, in which HI decomposition and H₂ separation take place simultaneously. The section plays a major role in high hydrogen production efficiency (that depends on reaction conversion and separation efficiency) of the SI cycle. In the column simulation, the rigorous thermodynamic phase equilibrium and reaction kinetic model are used. The tuning parameters involved in phase equilibrium model are dependent on interactive components and system temperature. For kinetic model, parameter values are adopted from the Aspen flowsheet simulator. Interestingly, there is no side reaction (e.g., solvation reaction, electrolyte decomposition and polyiodide formation) considered aiming to make the proposed model simple that leads to a challenging prediction. The process parameters are determined on the basis of optimal hydrogen production as reflux ratio = 0.87, total number of stages = 19 and feeding point at 8th stage. With this, the column operates at a reasonably low pressure (i.e., 8 bar) and produces hydrogen in the distillate with a desired composition (H₂ = 9.18 mol%, H₂O = 88.27 mol% and HI = 2.54 mol%). Finally, the results are compared with other model simulations. It is observed that the proposed scheme leads to consume a reasonably low energy requirement of 327 MJ/kmol of H₂.

• 한국산학기술학회논문지
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• 제5권2호
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• pp.128-131
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• 2004

본 연구에서는 STS-ICP ASEHR을 이용하여 Etch와 Deposition 공정을 반복하여 에칭을 하는 Bosch 식각에 관하여 연구하였다. 기본적인 Etch rate의 변화는 Etching하고자 하는 Wafer에 Deposition된 PR 또는 SiO₂의 두께와 Etching하고자 하는 Wafer의 Depth 및 Pattern size가 영향을 준다. 그러나 이러한 기본적인 변수 외에 STS-ICP ASEHR 장비의 Platen power, Coil power 및 Process pressure에 다양한 변화를 주어 각 변수에 따른 Etch rate을 관찰하였다. 각 공정별 변수를 준 결과 Platen power 12W, Coil power 500W, Etch/Passivation Cycle 6/7sec 일 경우 Etch rate은 1.2㎛/min 이었고, Sidewall prpfile은 90±0.2˚로 나타나 매우 우수한 결과를 보였다. 이는 ICP를 이용한 Bosch Process에 의한 결과임을 확인할 수 있었다.