• Korean Chemical Engineering Research
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• 제61권2호
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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.

• 한국가구학회지
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• 제20권3호
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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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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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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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• 제2권3호
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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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• 제46권4호
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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.

• 산업식품공학
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• 제23권2호
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• pp.87-93
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• 2019

공기 주입식 스팀-에어 레토르트 내에서 스팀온도, 내부가압, CUT 등의 공정변수가 레토르트 내부의 온도 균일성에 미치는 영향을 평가하였다. 고온살균(121℃)이 저온살균(82℃) 보다 공정구간동안 온도분포가 더 균일하고 안정적이었다. 내부 가압이 클수록 저온살균조건의 공정에서는 온도분포가 안정적이었고, 이와 반대로 고온살균조건의 공정에서 온도분포가 더 불균일한 것으로 나타났다. 승온구간을 조절한 경우에는 레토르트 내의 온도분포에는 유의적인 차이를 나타내지 않았다. 공정구간동안 레토르트 내부에서 냉점은 수직방향 1층의 위로 확인되었고, 수평방향에서는 맨 뒤쪽 중앙 부분이 가장 높은 온도를 유지하여 공정 동안 이 위치들을 주의를 할 필요가 있었다. 또한 레토르트 내부의 양 옆 위치가 다른 위치에 비해 특히 온도분포가 불안정한 것으로 확인되었으므로 레토르트 가공 공정에서 주의해야 할 것으로 판단되었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
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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.

• 한국산학기술학회논문지
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• 제17권4호
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• pp.766-771
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• 2016

본 연구에서는 저심도 도시철도시스템 구축시 건설비용의 절감을 위하여 산업부산물인 고로슬래그 미분말과 플라이애쉬로 결합재의 일부를 대체하고, 급냉 전기로 산화슬래그를 잔골재의 대체재료로 사용한 저탄소 친환경 콘크리트와 우수한 조기강도 확보와 양생비용 절감을 위한 마이크로웨이브 발열거푸집으로 제작한 PC BOX의 장기내구성 평가를 수행하였다. 평가결과, 초기강도는 발열양생 조건이 증기양생 조건에 비해 다소 높게 나타났지만 장기재령 강도는 거의 대등한 것으로 나타났다. 또한 화학저항성 및 동결융해 저항성 평가 결과, 재령별 발열 및 증기양생을 통해 제작된 PC BOX의 성능차이는 없는 것으로 나타났으며, 염소이온침투성 평가 결과 역시 발열 및 증기양생 PC BOX 모두 매우 낮은 등급의 수준을 확보하는 것으로 나타났다. 따라서 저탄소 친환경 콘크리트와 발열양생시스템을 적용하여 저심도 철도시스템용 PC BOX를 제작할 경우, 기존 증기양생방법과 대등한 내구성능을 확보할 수 있어 저비용의 저심도 철도시스템 콘크리트 인프라 구축에 기여할 수 있으며, 또한 증기양생 시 사용되는 화석연료의 사용량을 제로화해 이산화탄소 배출 및 환경부하를 저감할 수 있을 것으로 기대된다.

• 대한가정학회지
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• 제17권2호
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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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• 제27권7호
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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.