• Journal of the Korea Convergence Society
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• v.10 no.4
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• pp.131-138
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• 2019

Diesel engines have important advantages over its gasoline counterpart including high thermal efficiency, high fuel economy and low emissions of CO, HC and $CO_2$. However, NOx reducing is more difficult on diesel engines because of the high $O_2$ concentration in the exhaust, marking general three way catalytic converter ineffective. Two method available technologies for continuous NOx reduction onboard diesel engines are Urea-SCR and LNT. The implementation of the Urea-SCR systems in design engines have made it possible for 2.5l and over engines to meet the tightened NOx emission standard of Euro-6. In this study, we investigate the characteristics of NOx reduction with respect to engine speed, load, types of catalyst and the $NH_3$/NOx ratio and present the conditions which maximize NOx reduction. Also we provide detailed experimental data on Urea-SCR which can be used for the preparation for standards beyond Euro-6.

• Journal of Information Technology Applications and Management
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• v.25 no.3
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• pp.17-28
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• 2018

In this paper, an activity-oriented usability model is proposed. The usability model contains two types of characteristics: special-type characteristics of usability and sub-characteristics of usability. Workability, study-ability, and playability are, but do not exhaust, examples of special-type characteristic of usability. They correspond to working, studying, and playing using the software product, respectively. They represent the goal of using and can overlap each other. They are usability too by themselves. Navigate-ability, data-prepare-ability, data-input-ability, response-wait-ability, output-examine-ability, and output-utilize-ability are typical examples of sub-characteristics of usability. They correspond to navigating, preparing data, inputting data, waiting response, examining output, and utilizing the output data, respectively. They are not usability by themselves. They constitute usability together as a group. Assessing is the fundamental and indispensable aspect of quality. Without assessing, the concept of quality has little practical value. Satisfaction, effectiveness, and efficiency are the most typical sub-characteristics of usability in existing quality models, which correspond to the evaluation criteria of usability. In the activity-oriented usability model, however, only the user's satisfaction is included: Satisfaction is regarded as the operational definition of usability in the user's view. As the result, usability can be interpreted as the 'goodness for using, which is evaluated by the user. 'Three fundamental principles regarding software quality models are proposed too in this paper: Principles of Parsimony, Cohesiveness, and Inheritance. Discussions illustrate well that typical existing usability models violate these basic principles. Many authors have tried to define general usability models which can be applied to most kinds of software. The dream of the general and universal usability model, however, may be an illusion. The activity-oriented usability model is expected to serve as a prototype from which specialized usability models can be derived.

• Membrane Journal
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• v.33 no.6
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• pp.344-351
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• 2023

The membrane separation process for carbon dioxide capture from hydrogen reformer exhaust gas has been developed. Using a commercial membrane module, a multi-stage process was developed to achieve 90% of carbon dioxide purity and 90% of recovery rate for ternary mixed gas. Even if a membrane module with being well-known properties such as material selectivity and permeability, the process performance of purity and recovery widely varies depending on the stage-cut, the pressure at feed and permeate side. In this study, we verify the limits of capture efficiency at single-stage membrane process under various operating conditions and optimized the two-stage recovery process to simultaneously achieve high purity and recovery rate.

• Journal of Animal Environmental Science
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• v.10 no.2
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• pp.93-100
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• 2004

An experiment was conducted to establish comparison of ventilation efficiency in an enclosed and conventional growing-finishing pig house. The experimental pigs were in winter and summer. The main results of the experiment are as follows : Then the air from planar slot inlet the pig house flow out through the sidewall outlet operated by exhaust fan(Gl). The second structure has an air input through the circular duct inlet are plated side the juncture of the entering wall and the air into the pig house flow out through the chimney and pit outlet are operated by exhaust fan(G2). Through the air into relay fan the pig house flow out through the curtains in sidewall(G3). Similarly, air comes in through the circular duct inlet are placed the air into the pig house flow out through the curtains in sidewall (G4). Air flow rate on the floor level which is the low part of pen and the living area of pigs in the G2 and G4 system during winter was measured at 0.2 to 0.3 m/s at the 0.5 to 0.6 m/s at the maximum ventilation efficiency. As for the results of detrimental gas(ammonia) concentration ratio analysis, while G2 and G4 system sustained of summer 13.3 $\~$ 16.6 ppm, winter 14.0 $\~$ 14.6 ppm level, Gl and G3 system sustained of summer 14.6 $\~$ 20.3 ppm, winter 20.3 $\~$ 25.0 ppm, and the latter one is lower than that of the G1 and G3 system.

• Korean Journal of Materials Research
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• v.23 no.4
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• pp.219-226
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• 2013

Activated magnetite ($Fe_3O_{4-{\delta}}$) has the capability of decomposing $CO_2$ proportional to the ${\delta}$-value at comparatively low temperature of $300^{\circ}C$. To enhance the $CO_2$ decomposition capability of $Fe_3O_{4-{\delta}}$, $(Fe_{1-x}Co_x)_3O_{4-{\delta}}$ and $(Fe_{1-x}Mn_x)_3O_{4-{\delta}}$ were synthesized and then reacted with $CO_2$. $Fe_{1-x}Co_xC_2O_4{\cdot}2H_2O$ powders having Fe to Co mixing ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 were synthesized by co-precipitation of $FeSO_4{\cdot}7H_2O$ and $CoSO_4{\cdot}7H_2O$ solutions with a $(NH_4)_2C_2O_4{\cdot}H_2O$ solution. The same method was used to synthesize $Fe_{1-x}Mn_xC_2O_4{\cdot}2H_2O$ powders having Fe to Mn mixing ratios of 9:1, 8:2, 7:3, 6:4, 5:5 with a $MnSO_4{\cdot}4H_2O$ solution. The thermal decomposition of synthesized $Fe_{1-x}Co_xC_2O_4{\cdot}2H_2O$ and $Fe_{1-x}Mn_xC_2O_4{\cdot}2H_2O$ was analyzed in an Ar atmosphere with TG/DTA. The synthesized powders were heat-treated for 3 hours in an Ar atmosphere at $450^{\circ}C$ to produce activated powders of $(Fe_{1-x}Co_x)_3O_{4-{\delta}}$ and $(Fe_{1-x}Mn_x)_3O_{4-{\delta}}$. The activated powders were reacted with a mixed gas (Ar : 85 %, $CO_2$ : 15 %) at $300^{\circ}C$ for 12 hours. The exhaust gas was analyzed for $CO_2$ with a $CO_2$ gas analyzer. The decomposition of $CO_2$ was estimated by measuring $CO_2$ content in the exhaust gas after the reaction with $CO_2$. For $(Fe_{1-x}Mn_x)_3O_{4-{\delta}}$, the amount of $Mn^{2+}$ oxidized to $Mn^{3+}$ increased as x increased. The ${\delta}$ value and $CO_2$ decomposition efficiency decreased as x increased. When the ${\delta}$ value was below 0.641, $CO_2$ was not decomposed. For $(Fe_{1-x}Co_x)_3O_{4-{\delta}}$, the ${\delta}$ value and $CO_2$ decomposition efficiency increased as x increased. At a ${\delta}$ value of 0.857, an active state was maintained even after 12 hours of reaction and the amount of decomposed $CO_2$ was $52.844cm^3$ per 1 g of $(Fe_{0.5}Co_{0.5})_3O_{4-{\delta}}$.

• Clean Technology
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• v.21 no.2
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• pp.130-139
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• 2015

The NO oxidation process has been applied to improve a removal efficiency of NO included in exhaust gas. In this study, to produce a dry oxidant for the NO oxidation process, the catalytic H₂O₂ decomposition method was proposed. A variety of the heterogeneous solid-acidic Mn-based catalysts were prepared for the catalytic H₂O₂ decomposition and the effect of their physico-chemical properties on the catalytic H₂O₂ decomposition were investigated. The results of this study showed that the acidic sites of the Mn-based catalysts has an influence on the catalytic H₂O₂ decomposition. The Mn-based catalyst having the abundant acidic sites within the wide temperature range in NH₃-TPD shows the best performance for the catalytic H₂O₂ decomposition. Therefore, the NO oxidation efficiency, using the dry oxidant produced by the H₂O₂ decomposition over the Mn-based catalyst having the abundant acidic properties under the wide temperature range, was higher than the others. As a remarkable result, the best performances in the catalytic H₂O₂ decomposition and NO oxidation was shown when the Mn-based Fe₂O₃ support catalyst containing K component was used for the catalytic H₂O₂ decomposition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.1
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• pp.35-43
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• 2010

In this study, an ideal water-recirculated oxy-fuel power generation system is proposed. The results of parametric studies of the performance characteristics of the system are discussed. For a given choice of the turbine inlet temperature, the turbine, which produces power, can be either a gas or a steam turbine. For maximum efficiency, the turbine inlet temperature is selected as the level of state-of-the-art gas turbines and the reheat cycle may be adopted not only to enhance the turbine power but also to maintain dryness of the water with a turbine exhaust temperature that is as high as possible. To obtain a low condensation temperature for a high purity of $CO_2$, a relatively low pressure expansion process may be added. Finally, the performance of the water-recirculated oxy-fuel power generation system is discussed with reference to various operating parameters and system configurations. The optimal operating conditions for high performance and a high purity of $CO_2$ are proposed.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.20-27
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• 2012

The $NH_3$-SCR characteristics of $NO_X$ over a V-based catalyst are experimentally examined over a wide range of operating conditions, i.e., $170-590^{\circ}C$ and $30,000-50,000h^{-1}$, with a simulated diesel exhaust containing $NH_3$, NO, $NO_2$, $O_2$, $H_2O$, and $N_2$. The influences of the space velocity and oxygen concentration on the standard-SCR reaction are analyzed, and it is shown that the low space velocity and high oxygen concentration promote the SCR activity by ammonia. The best $deNO_X$ efficiency is obtained with a $NO_2/NO_X$ ratio of 0.5 because of an enhanced chemical activity induced by the fast-SCR reaction, while at the $NO_2/NO_X$ ratios above 0.5 the $deNO_x$ activity decreases due to the slow-SCR reaction. The oxidation of ammonia begins to take place at about $300^{\circ}C$ and the reaction products, such as $N_2$, NO, $NO_2$, $N_2O$, and $H_2O$, are produced by the undesirable oxidation reactions of ammonia, particularly at high temperatures above $450^{\circ}C$. Also, $NO_2$ decomposes to NO and $O_2$ at temperatures above $240^{\circ}C$. Therefore, $NO_2$ decomposition and ammonia oxidation reactions deteriorate significantly the SCR catalytic activity at high temperatures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.14-20
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• 2018

Electric vehicles are environmentally friendly because they emit no exhaust gas, unlike gasoline automobiles. However, since they are driven by the electric power from batteries, the distance they can travel based on a single charge depends on their energy density. Therefore, the lithium-ion battery having a high energy density is a good candidate for the batteries of electric vehicles. Since the electrode is an essential component that governs their efficiency, the electrode manufacturing process plays a vital role in the entire production process of lithium-ion batteries. In particular, the coating process is a critical step in the manufacturing of the electrode, which has a significant influence on its performance. In this paper, we propose an innovative process for improving the efficiency and productivity of the coating process in electrode manufacturing and describe the equipment design method and development results. Specifically, we propose a design procedure and development method in order to improve the core plate coating quality by 25%, using a technology capable of reducing the assembly margin due to its high output/high capacity and improving the product capacity quality and assembly process yield. Using this method, the battery life of the lithium-ion battery cell was improved. Compared with the existing coating process, the target loading level is maintained and dispersed to maintain the anode capacity (${\pm}0.4{\rightarrow}{\pm}0.3mg/cm^2r$ reduction).

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2255-2261
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• 2000

To eliminate $NO_x$ in diesel emission. selective catalyst reduction (SCR) was used in real diesel engine. Among the SCR methods, metal oxide and perovskite catalysts were introduced in this paper. The removal efficiencies with various major, promoter catalysts on ${\gamma}-Al_2O_3$ at different reaction temperature were investigated, and $LaCuMnO_x$ catalyst which has high removal efficiency at the temperature of real diesel exhaust gas was selected. $NO_x$ reduction was carried out over these catalysts in the flow-through type reactor using by-pass ($SV=3,300h^{-1}$). Under the given condition to this study, perovskite catalysts showed considerably high removal efficiency and $LaCuMnO_x$ was the best one among these catalysts in the temperature range of $150{\sim}450^{\circ}C$.