• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.328-339
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• 2023

Methanol steam reforming (MSR) is a promising method for hydrogen supplying as a critical step in hydrogen fuel cell commercialization in mobile applications. Modelling and understanding of the reactor behavior is an attractive research field to develop an efficient reformer. Three-layer feed-forward artificial neural network (ANN) and Box-Behnken design (BBD) were used to modelling of MSR process using the Cu-SiO₂ aerogel catalyst. Furthermore, impacts of the basic operational variables and their mutual interactions were studied. The results showed that the most affecting parameters were the reaction temperature (56%) and its quadratic term (20.5%). In addition, it was also found that the interaction between temperature and Steam/Methanol ratio is important on the MSR performance. These models precisely predict MSR performance and have great agreement with experimental results. However, on the basis of statistical criteria the ANN technique showed the greater modelling ability as compared with statistical BBD approach.

• Journal of the Korea Furniture Society
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• v.20 no.3
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• pp.222-231
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• 2009

At researching the history of furniture design, furniture based on the bentwood technique was often seen. There are different bending ways of wood. Among others the steam bending technique had been used since long time, but it's detailed method has been much less studied in Korea yet. The aim of the present study was to investigate the theoretical approach and making ways & process of the steam bending technique, and furthermore to utilize it for the works of the students majoring furniture design. This intends that the steam bending technique will be widely distributed by doing a mock up and it will be diversely used for development of more different furniture designs.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.74-78
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• 1992

This paper describes an intelligent system to automatic evaluation of eddy current(EC) signal for Inspection of steam generator(SG) tubes in nuclear power plant. Some features of the intelligent system design in the proposed system are : (1) separation of representation scheme ,or event capturing knowledge in EC signal and for structural inspection knowledge in SG tubes inspection; (2) each representation scheme is implemented in different methods, one is syntactic pattern grammar and the other is rule based production. This intelligent system also includes an data base system and an user interface system to support integration of the hybrid knowledge processing methods. The intelligent system based on the proposed concept is useful in simplifying the knowledge elicitation process of the rule based production system, and in increasing the performance in real time signal inspection application.

• International Journal of Fluid Machinery and Systems
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• v.2 no.3
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• pp.248-253
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• 2009

This paper presents a numerical study for unsteady flows in a high-pressure steam turbine with a partial admission stage. Compressible Navier-Stokes equations are solved by the high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD scheme, Roe's approximate Riemann solver, and the LU-SGS scheme. The SST-model is also solved for evaluating the eddy-viscosity. The unsteady two-dimensional flows through whole nozzle-rotor cascade channels considering a partial admission are numerically investigated. 108 nozzle passages with two blockages and 60 rotor passages are simultaneously calculated. The influence of the flange in the nozzle box to the lift of rotors is predicted. Also the efficiency of the partial admission stage changing the number of blockages and the number of nozzles is parametrically predicted.

• Journal of the Korean Wood Science and Technology
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• v.46 no.4
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• pp.380-392
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• 2018

The importance of polysaccharides is increasing globally due to their role as a significant source of dietary prebiotics in the human diet. In the present study, in order to maximize the yield of crude polysaccharides from Pinus densiflora, response surface methodology (RSM) was used to optimize a two-stage extraction process consisting of steam explosion and water extraction. Three independent main variables, namely, the severity factor (Ro) for the steam explosion process, the water extraction temperature ($^{\circ}C$), and the ratio of water to raw material (v/w), were studied with respect to prebiotic sugar content. A Box-Behnken design was created on the basis of the results of these single-factor tests. The experimental data were fitted to a second-order polynomial equation for multiple regression analysis and examined using the appropriate statistical methods. The data showed that both the severity factor (Ro) and the ratio of water to material (v/w) had significant effects on the prebiotic sugar content. The optimal conditions for the two-stage process were as follows: a severity factor (Ro) of 3.86, a water extraction temperature of $89.66^{\circ}C$, and a ratio of water to material (v/w) of 39.20. Under these conditions, the prebiotic sugar content in the extract was 332.45 mg/g.

• Food Engineering Progress
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• v.23 no.2
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• pp.87-93
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• 2019

Temperature distribution studies were performed in steam-air retort to investigate the influence of various processing conditions (come-up time, sterilization temperature, and internal pressure throughout the steam-air retort). Retort temperature data were analyzed for temperature deviations during holding phase, maximum temperature difference between test locations at the beginning and after 1, 3, and 5 min of the holding phase, and box-and-whiskers plots for each location during the holding phase. The results showed that high sterilization temperature led to a more uniform temperature distribution than low sterilization temperature (pasteurization). In pasteurization condition, the temperature stability was slightly increased by increasing pressure during the holding phase. On the other hand, the temperature stability was slightly decreased in high sterilization temperature condition. Programming of the come-up phase did not affect the temperature uniformity. In addition, the slowest cold spot was found at the bottom floor during the holding phase in all conditions. This study determined that the temperature distribution is affected by retort processing conditions, but the steam-air retort needs more validation tests for temperature stability.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1259-1264
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• 1990

During the past two decades, a lot of researches have been done on the synthesis of grassroot heat exchanger networks(HEN). However, few have been dedicated to retrofit of existing heat exchanger networks, which usually use more amount of utilities (i.e. steam and/or cooling water) than the minimum requirements. This excess gives motivation of trades-off between energy saving and rearranging investment. In this paper, an algorithmic-evolutionary synthesis procedure for retrofitting heat exchanger networks is proposed. It consists of two stages. First, after the amount of maximum energy recovery(MER) is computed, a grass-root network featuring minimum number of units(MNU) is synthesized. In this stage, a systematic procedure of synthesizing MNU networks is presented. It is based upon the concept of pinch, from which networks are synthesized in a logical way by the heuristics verified by the pinch technology. In the second stage, since an initial feasible network is synthesized based on the pre-analysis result of MER and must-matches, an assignment problem between new and existing units is solved to minimize total required additional areas. After the existing units are assigned, the network can be improved by switching some units. For this purpose, an improvement problem is formulated and solved to utilize the areas of existing units as much as possible. An example is used to demonstrate the effectiveness of the proposed method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.766-771
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• 2016

This study examined the long-term durability of PC boxes, which was manufactured by low-carbon eco-friendly concrete using an alternative binder to cement and alternative fine aggregate to sand and microwave heat curing system to reduce the construction cost of a near-surface transit system. Based on the test results, the initial compressive strength of microwave heat cured concrete was higher than that of the steam cured concrete, but those were similar in the long-term age. In addition, there was no significant difference between the two curing conditions in the chemical resistance and the freeze-thawing resistance, and the chloride ion penetration level of the concrete cured by two methods was very low. Therefore, low-carbon eco-friendly concrete and microwave heat curing technology are expected to contribute to the economic construction of a near-surface transit system, and reduce carbon dioxide emissions and environmental impact.

• Journal of the Korean Home Economics Association
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• v.17 no.2
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• pp.32-38
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• 1979

The purpose of this experiment was to find out the contained quantity of ascorbic acid form persimmon tea. They were different according to the month when the persimmon leaves were picked, the way of cooking and the length of time spent after cooking. The results of experiment can be summarized as follows : 1. About the same contained quantities of ascorbic acid were obtained among the persimmon leaves picked in September and October, and small contained quatities of it were obtained among the persimmon leaves picked in November. Therefore it can be concluded that the persimmon leaves picked in September and October are better than the leaves picked in November for permision tea. 2. According to the way of cooking the contained quantity of ascorbic acid were different. When green leaves were washed and boiled for 1 monute and dried in the shade for 48 hours, the largest contained quantity of ascorbic acid were obtained. When they were steamed in the steam box for 1 minute and 30 seconds and dried in shade for 48 hours medium contained quantity of ascorbic acid were obtained . The contained quantity of ascorbic acid were decreased when green leaves were dried without boiling when green leaves were dried without boiling or when branches of leaves were taken away by hand and dried. 3. The contained quantity of ascobic acid were also different according to the length of time spent after cooking. After 15 minutes from cooking it began to increase and after 150 minutes it reached the highest degree. After this time it began to decrease. 4. the best fragrance, taste and color of the Persimmn Tea are found out, after steaming in the steaming box for one minute and half second and after drying in the shade for fourty-eight hours.

• Journal of Microbiology and Biotechnology
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• v.27 no.7
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• pp.1209-1215
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• 2017

Microwave sterilization was performed to inactivate the spores of biofilms of Bacillus cereus involved in foodborne illness. The sterilization conditions, such as the amount of water and the operating temperature and treatment time, were optimized using statistical analysis based on 15 runs of experimental results designed by the Box-Behnken method. Statistical analysis showed that the optimal conditions for the inactivation of B. cereus biofilms were 14 ml of water, $108^{\circ}C$ of temperature, and 15 min of treatment time. Interestingly, response surface plots showed that the amount of water is the most important factor for microwave sterilization under the present conditions. Complete inactivation by microwaves was achieved in 5 min, and the inactivation efficiency by microwave was obviously higher than that by conventional steam autoclave. Finally, confocal laser scanning microscopy images showed that the principal effect of microwave treatment was cell membrane disruption. Thus, this study can contribute to the development of a process to control food-associated pathogens.