• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.122-122
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• 2009

금속기판과 액체금속의 젖음성은 일반적으로 액적법 (sessile drop)에 의해 고체와 액체간의 접촉각 측정을 통해서 알 수 있다. 이러한 방법에 의한 젖음성 실험결과는 고체와 액체계면에서의 반응이 무시될 수 있는 경우에 적용가는 하지만 연속용용도금공정과 같이 용융된 금속내부로 강판이 인입되는 과정에서 계면반응이 동적으로 진행되는 과정에서의 젖음성을 모사하기에는 이러한 방법의 신뢰성이 떨어지는 문제점이 있다. 따라서 본 연구에서는 실제 용융도금공정과 유사하게 소둔열처리된 저탄소강판이 환원성분위기내에서 Zn 및 Zn-Al 용융도금욕 내부로 연속적으로 인입되는 과정에서의 젖음력 및 접촉각 등의 측정을 통해 실제 도금공정상의 도금성과 젖음성의 연관성을 규명하고자하였다. 연구결과 일반적인 Zn 도금욕의 경우 젖음성이 양호하지만 Al함량이 높은 경우에는 젖음성이 좋지 못한 것으로 나타났다.

• Journal of Hydrogen and New Energy
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• v.21 no.5
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• pp.460-469
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• 2010

To develop coal gasfication system, many studies have been actively conducted to describe the simulation of steady state. Now, it is necessary to study the gasification system not only in steady state but also in dynamic state to elucidate abnormal condition such as start-up, shut-down, disturbance, and develop control logic. In this study, a model was proposed with process simulation in dynamic state being conducted using a chemical process simulation tool, where a heat and mass transfer model in the gasifier is incorporated, The proposed model was verified by comparison of the results of the simulation with those available from NETL (National Energy Technology Laboratory) report under steady state condition. The simulation results were that the coal gas efficiency was 80.7%, gas thermal efficiency was 95.4%, which indicated the error was under 1 %. Also, the compositions of syngas were similar to those of the NETL report. Controlled variables of the proposed model was verified by increasing oxygen flow rate to gasifier in order to validate the dynamic state of the system. As a result, trends of major process variables were resonable when oxygen flow rate increased by 5% from the steady state value. Coal flow rate to gasifier and quench gas flow rate were increased, and flow rate of liquid slag was also increased. The proposed model in this study is able to be used for the prediction of gasification of various coals and dynamic analysis of coal gasification.

• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.217-225
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• 2023

2,3-Butanediol (2,3-BDO), which is used in various fields such as cosmetics and fertilizers, is a high value-added substance and the demand for it is gradually increasing. 2,3-BDO produced from the fermentation of microorganisms not only contains by-products of fermentation, but also varies greatly in feed composition depending on fermentation conditions, so it is difficult to efficiently operate the separation process to reach the target purity of the product. Therefore, in this study, through dynamic optimization of the bio-based 2,3-BDO distillation process, the optimal control route was explored to control the 2,3-BDO concentration of the bottom product to 99 wt% or more, when feed concentration changes. Steady and dynamic state process simulation, proportional integral (PI) controller design, and dynamic optimization were sequentially performed. As a result, the error between the 2,3-BDO concentration and the set point of the bottom product was reduced by 75.2%.

• Clean Technology
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• v.14 no.1
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• pp.47-52
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• 2008

Among various mass transfer models to express adsorption rates for any adsorption processes, the linear driving force (LDF) model is used most. The present investigation aims at finding whether this model may be applied to real adsorption process for separation and removal of benzene. Comparison of numerical simulation results calculated by the LDF model with experimental data allowed us to find the mass transfer coefficients that are most appropriate for a specific adsorption process. Various breakthrough curves were obtained from experiments performed at many different temperatures and pressures, which in turn produced suitable mass transfer coefficients. These dependencies of mass transfer coefficient on temperature and pressure were represented by an Arrhenius type- and a power law type empirical equation, respectively.

• Journal of Hydrogen and New Energy
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• v.28 no.4
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• pp.352-360
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• 2017

Polygeneration process is widely used to pursuit high efficiency by sharing electricity, utility, refrigeration and the utilization of product chemicals. In this paper, performance analysis of the 450 MW Class polygeneration process was conducted with various syngas generated from coal and biomass gasifier. WGSR and PSA process were employed for hydrogen production and separation. Process modeling and dynamic simulation was carried out, and the results were compared with NETL report. Net power of the polygeneration process was 439 MW considering power consumption. More than 90% of CO was converted at WGSR and the hydrogen purity of PSA was more than 99.99%.

• Journal of Energy Engineering
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• v.6 no.1
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• pp.87-95
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• 1997

A chemical heat pump based on the reversible reactions between metal chlorides and ammonia gas is attractive alternative to compression system and liquid absorption systems in cooling and refrigerating fields. The advantages of chemical heat pump are no regulatory constants due to CFC refrigerants, utilization of gas, industrial waste heat, electricity, fuel oil etc. as heat sources and wide applications to energy storage system, large-scale energy managements for industrial process. The scale-up of chemical heat pump from laboratory prototype to pilot plants necessitates the interpretation of system performance and evaluation of dynamic behavior in the chemical reactor. This study contains the prediction of performance of chemical refrigerator according to operating condition, the dynamic simulations through reactor modelling, which is used for the calculation of reactive medium temperature and the conversion variation with reactor cooling temperature, and the effect survey of block parameters on the power of refrigerator.

• Korean Chemical Engineering Research
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• v.52 no.5
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• pp.613-619
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• 2014

A flare system is a very important system that crucially affects on the process safety in chemical plants. If a flare system is designed too small, it cannot prevent catastrophic accidents of a chemical plant. On the other hand, if a flare system is designed too large, it will waste resources. Therefore, reasonable relief load estimation has been a crucial issue in the industry. American Petroleum Institute (API) suggests basic guidelines for relief load estimation, and a lot of engineering companies have developed their own relief load estimation methods that use an unbalanced heat and material method. However, these methods have to involve lots of conservative assumptions that lead to an overestimation of relief loads. In this study, the new design procedure for a flare system based on dynamic simulation was proposed in order to avoid the overestimation of relief loads. The relief load of a deethanizer process was tested to verify the performance of the proposed design procedure.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.310-318
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• 1999

The concentration breakthrough curves were examined to predict mass transfer coefficients of nitrogen and oxygen in adsorption column for design data of PSA process. Experimental breakthrough curves for bulk gas flow were compared with theoretical simulation results. For quantitative analysis of the adsorption, coupled Langmuir isotherm was considered and LDF model was used to describe the mass transfer effect. In the experimental and theoretical results, it was found that mass transfer coefficient was not affected by flow rate but strongly affected by pressure. As a result of this tendency, mass transfer resistance in this system was proved to belong to the macropore diffusion controlling region and the mass transfer coefficients could be expressed by exponential functions of pressure change. The mass transfer coefficients for one component, nitrogen or oxygen, were successfully applied to breakthrough curves for bulk mixed gases. The experimental curves were reasonably in consistent with the theoretical curves and the error time was less than 5 percent.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1520-1523
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• 1997

A rigorous dynamic simulation was performed in binary gas mixture H$_{2}$/CO (70:30 vol.%) to determinate start-up operating conditions of PSA(Pressure Swing Adsorption) processes. The rigorous dynamic model for the PSA process contains an Ergun equation for expressing the pressure drop in a bed, and valve equations to compute the boundary pressure change of the bed. As the result of the continuous dynamic simulation of 100 operating cyles in various initial conditions, the unsteady-state appeared in the early period and the cyclic steady-state came out about 20th cycle in feed condition and vaccum condition, and 30th cycle in pure H$_{2}$ condition. As time goes by valve equations made change the pressure at each end of the bed in ressurization, countercurrunt-depressurization and pressure equalization steps. The H$_{2}$ purity and the recovery is 99.99% and 86.73% respectively, which is slightly higher than the experimental data. Main contributiion of this study includes supplying fundamental technologies of handling combined variables PSA processes by developing rigorous models.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2004.04a
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• pp.117-126
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• 2004

This paper presents a linear model for heat transfer processes in the drying cylinders and the web in papar mill. The PDE model, functions include steam temperatures, wet temperatures, moisture constents, reel speed and basis weight were derived from operation data. The changes of wet temperatures and moisture contents in the drying cylinders and wets could be described. The Transfer function can be obtained through the state space model derived from the linearized PDE model. Stability of the drying cylinder model for paper plants and analysis of characteristics of process responses for changes in input variables are investigated.