• Korean Journal of Food Science and Technology
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• v.23 no.6
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• pp.683-688
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• 1991

Wheat flour was extruded by a single-screw extruder, and used for the ethanol production of takju. The molecular structure and enzymic susceptability of extruded starch were compared to those of steam cooked one. The gel permeation chromatographic pattern of wheat flour extrudates was not significantly different from those of raw and steam cooked starches. However, the conversion rate of extruded starch into maltose by ${\alpha}-amylase$ hydrolysis was significantly faster than those of raw ad steamed starch. The molecular weight of starch estimated from GPC pattern and the intrinsic viscosity were remarkably reduced by extrusion cooking followed by the enzymic hydrolysis for 30 min, while steam cooking and enzymic hydrolysis for 30 min did not change them significantly. Extrusion-cooked flour produced alcohol 26% higher than that of steamed flour in the laboratory takju fermentation, and 10% more alcohol in the pilot plant scale takju production.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.367-371
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• 2019

The molding for hollow products used widely in industry is rotational molding by heating and cooling. Uniform cooling is required to improve the quality of the product, and rapid cooling is required to improve the productivity. In this paper, the cooling condition is largely classified into the case of no forced cooling by the fan and forced cooling by the fan. In addition, when forced cooling by the fan is not performed, the condition for stopping the molding machine horizontally and the condition for stopping the molding machine vertically were classified. To confirm the forced cooling by the fan, the conditions were set such that only the molding machine rotates while the fan is not running and the upper and lower fans operate when only the lower fan is operated. The surface temperature of the rotary molding machine was analyzed by the STAR-CCM+ program for the case of air-cooling. The temperature distribution of the rotary molding machine was analyzed for five conditions and the temperature distribution for cooling was compared under each condition. Among the five cases, Case 4 was lowest at approximately 35 ℃ after 900sec.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.3
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• pp.134-143
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• 1999

The ship's bows and sterns are assembled with the curved blocks. In shipyards, the roller bending and the line heating or others are being used to fabricate such doubly curved shell. Firstly, the cylinder- or cone-type is formed through the roller bending, and then, the line heating is implemented to form the rest. This paper presents an algorithm to determine the direction for the roller bending and the shape to be formed as fabrication information. The direction for the roller bending is determined with Gauss mapping of the desired surface and the shape to form is calculated by comparing the bent shape with the desired shape.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.567-568
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• 2006

Generally, progressive type GMP process is more efficient than batch type because there are advantages that problems of each stage(heating, press, cooling etc.) are easily grasped and a time of production is shortened. But if single cavity is used in progressive type GMP process, there is disadvantage that productivity is decreased. So, in order to improve productivity of progressive type GMP process, it is essential to secure multi cavity mold technic. In this study, as a fundamental study to develop multi cavity used in glass lens molding, we conducted a compression test for PBK40.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.282-287
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• 2007

Hot embossing, one of Nanoimprint Lithography(NIL) techniques, has been getting attention as an alternative candidate of next generation patterning technologies by the advantages of simplicity and low cost compared to conventional photolithographies. A typical hot embossing usually, however, takes more than ten minutes for one cycle of the process because of a long thermal cycling. Over the last few years a number of studies have been made to reduce the cycle time for hot embossing or similar patterning processes. The target of this research is to develop an induction heating apparatus for heating a metallic micro patterning mold at very high speed with the large-area uniformity of temperature distribution. It was found that a 0.5 mm-thick nickel mold can be heated from $25^{\circ}C\;to\;150^{\circ}C$ within 1.5 seconds with the temperature variation of ${\pm}5^{\circ}C$ in 4-inch diameter area, using the induction heating apparatus.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.4
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• pp.417-425
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• 2008

In the line heating process, only angular distortion whose direction is perpendicular to that of a heating path is expected. However, it is observed that a deformation is induced in the direction of the heating line. Because of this, during forming a saddle type plate we experience unfavorable deformations in the unintended direction. In this paper we discuss the unwanted distortion in the manufacturing process by analyzing intermediate plates of saddle type during fabrication. For this analysis we consider the longitudinal and transversal directions separately and use the bending strain for the analysis.

• Journal of Life Science
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• v.19 no.4
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• pp.486-491
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• 2009

This study was conducted to investigate microbial distribution in the processing steps and to estimate quality index and shelf life of packaged Tofu (soybean curd). Sanitation and safety of Tofu were analysed in aspects of total viable counts (TVCs) and coliforms. Organoleptic deterioration was observed from some packaged Tofu when their TVCs were over $10^6\;CFU/g$. The controlled simply packaged Tofu and sterilized Tofu with TVCs of under $10^5\;CFU/g$ were 32.0% and 86.9% of the total samples, respectively. Also, the controlled simply packaged Tofu and sterilized Tofu with negative coliforms were 12.0% and 83.7% of the total samples, respectively. TVCs and coliforms increased in some processing steps, which include washing and soaking of raw soybeans, and formation and 1st cooling of packaged Tofu. Increases of TVCs and coliforms in the washing and soaking step were due to contamination from the soaking tank and airborne bacteria, whereas increases of TVCs and coliforms in the grinding step were due to contaminations from the grinder, line and reserving tank. TVCs and coliforms increased in the formation and 1st cooling step of packaged Tofu due to contaminations from filter wools, trays, employee's hands, cooling water, formed products and filter wools.

• Journal of the Korean Wood Science and Technology
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• v.30 no.1
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• pp.25-33
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• 2002

Improvement of density profile and sound absorption capability of particleboard was attempted. Three types of hot pressing methods examined ; flat-platen pressing method (A-type pressing), hot pressing in forming box (B-type pressing), and hot pressing set up jagged caul in forming box (C-type pressing). The raw materials were larch(Larix leptolepis (S, et. Z.) Gorden) shavings, phenol formaldehyde resin, and the particleboard perforated with stair type. The physical and mechanical properties such as specific gravity, bending strength (MOR), internal bonding strength (IB) and sound absorption coefficients were examined. The results are summarized as follows : 1) The MOR and internal bonding strength of the board pressed in forming box were higher than those of flat-platen pressed board. 2) The minimum density to average density ratio in thickness direction which pressed in forming box showed about 923%, in the case of 35 mm commercial particleboard and 50 mm flat-platen pressed board, its values showed about 66.4% and 865% respectively. 3) Sound absorption coefficients of the particleboard perforated with stair type were higher than those of flat-plated pressed board and commercial particleboard.

• The Korean Journal of Food And Nutrition
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• v.10 no.2
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• pp.234-240
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• 1997

Agar has widely been used as medical aids and food ingredients due to its pecular physicochemical and rheological properties. In this paper, the effects of spray drying and extrusion drying on functional properties of agar were investigated to clarify the sol-gel transition mechanism at low temperature and microstructure of agar gel by measuring phase transition by differential scanning calorimetery, structural differences by light microscope and scanning electron microscope observation. The lowest endothermic onset(To), peak(Tp), conclusion(Tc) temperature and enthalpy($\Delta$H) using differential scanning calorimetery were showed in extrusion-dried agar wic were checked in 41.30, 61.72, 80.50 and 0.73cal/g. In cases of unmodified and spray-dried, the values were 81.20, 95.51, 112.14 and 3.22cal/g, and 60.11, 76.45, 89.54 and 1.53cal/g, respectively. When all samples were reheated using differential scanning calorimetery after gelling fully, no significant differences of endothermic To, Tp, Tc and $\Delta$H appeared. The surface structure of unmodified agar powder observed by light microscope and scanning electron microscope appeared a continuous surface without any indication of small pores, gaps or point of discontinuity. In cases of spray-dried agar, the unstable structures with pores was resulted. The microstructures of extrusion-dried agar, however, was solid with large gaps and areas of discontinuity in the surface. From the results above, it was suggested that significant differences in phase transition and surface microstructures were clearly related to the physicochemical changes and rheological properties, solubility and gelling ability of the types of agar gel.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.4
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• pp.50-55
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• 2014

Currently, flat cover glasses are widely applied to mobile devices. However, for a good design and for convenience of use, curved cover glasses are in demand. Thus, many companies are attempting to produce curved cover glasses using a shaving technique, but the production efficiency is very low. Therefore, a molding technique has been adopted to increase the efficiency of curved glass production systems. For a glass molding system, a uniform temperature distribution of the mold is crucial to produce high-quality curved cover glasses. Before setting the heating conditions of the molding system for a uniform temperature distribution by a thermal analysis, verification is required. Therefore, in this study, temperature measurements were conducted for a prototype molding system and the experimental results were compared with simulation computations. The temperatures of the heating block surface were in good agreement with the computational results for transient and steady conditions.