• Journal of the Korean Ceramic Society
• /
• v.37 no.12
• /
• pp.1178-1186
• /
• 2000

타일의 내마모성과 내산성을 향상시키기 위해 결정화유리가 최근에 새로운 유약 재료로서 소개되고 있다. 신 유약의 연구에 사용된 조성은 $Ca_2$ZrSi$_4$O$_{12}$ 상에 근접하는 CaO-ZrO$_2$-SiO$_2$계의 유리조성의 분말로, 마이크로파 가열 (2.45 GHz)에 의해서 900-120$0^{\circ}C$의 0-20분간 소성되어 평가되었다. 그 결과, 100$0^{\circ}C$ 이상에서 소성한 시편은 내부 결정화를 나타내었으며, 결정상은 미세(5$mu extrm{m}$)한 크기를 갖는 $Ca_2$ZrSi$_4$O$_{12}$가 주 결정상이며, $Ca_2$ZrSi$_4$O$_{12}$, CaSiO$_3$, SiO$_2$의 세 상이 나타났다. 소결체의 미세구조는 사용한 유리분말의 입도의 영향을 받았다. 미세분말 (<38$\mu\textrm{m}$)을 이용한 소결체의 조직이 조세분말 (45-150$\mu\textrm{m}$)의 경우보다 수축율면에서 높았으며 낮은 기공도를 갖는 미세구조를 가졌다. 마이크로파에 의한 유리분말의 소성은 1000-120$0^{\circ}C$ 구간에서 10분 이내 결정화가 완료되는 급속 가열 공정이었으며 CaO-ZrO$_2$-SiO$_2$계 결정화 유리 제조에 균일한 체적가열을 할 수 있었다.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.6
• /
• pp.1-7
• /
• 2022

This work investigated the performance improvement of a medium-pressure fixed-displacement-type SPUR gear pump, which is mainly used in the machine tool industry. The 3D CFX analysis and IS technique were applied using ANSYS (commercial FEM code) and compared with experimental results to ensure the reliability of the analysis. In addition, the performance improvement of the pump was obtained using the theoretical volumetric displacement equation, and the gear tooth width was changed. The pressure flow performance curves were compared, and the results were analyzed according to the width of the gear teeth. This is a factor that can cause irregular flow, vibration, and noise inside the gear pump owing to friction between the housing and gear pump.

• Polymer(Korea)
• /
• v.24 no.2
• /
• pp.268-275
• /
• 2000

We investigated the effect of polymer sublayer on volumetric resistivity and tensile strength of carbon fiber (CF)/polyethylene composite films fabricated under high intensity electric fields. The dependence of volumetric resistivity and tensile strength of the films on the polymer sublayer thickness or mass part exhibited complex behavior according to CF content and CF layer density in the films. As the thickness of polymer sublayer increases, two groups of processes at thermo-mechanical forming stage would take effects in the properties of the films. The first group comprises the increase of polymer layer thickness having reduced CF content compared with central or upper part of the film and insufficient wetting of CF resulting in the loosened structure near upper film side. The second group, on the other hand, is the improvement of mobility of molten sublayer leading to better distribution of CF throughout the film thickness and the formation of more compact structure. The different degree of contribution of these two competing processes at varied CF content and CF layer density could explain complex dependence of the film properties on the polymer sublayer. These results are important to optimize the electrical and mechanical properties of highly conductive polymer films, which can be used as electromagnetic interference shielding materials.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.40 no.9
• /
• pp.1285-1291
• /
• 2011

This study was conducted to evaluate the effect of lotus leaf and lotus root powder on the quality characteristics of sponge cake. Percentages of 4, 8 and 12% of two kinds of lotus powder were added to the batter based on flour content. Baking and cooling loss rate, volume and specific loaf volume, crumb color, texture, scanning electron microscopy (SEM) and sensory evaluation of the products were analyzed. The baking and cooling loss rate of the control was lower than cakes with added lotus leaf and lotus root powder. The volume of the control was the largest, and as the amount of lotus leaf and lotus root powder increased, volume and specific loaf volume became smaller. The lightness and yellowness values of the control were higher than those of the experimental cakes, and the loaves with 12% added lotus root powder showed the lowest value. Redness of the experimental cakes increased. In the textual property evaluation, hardness of the control and sponge cakes containing 4% lotus leaf, and lotus root powder appeared to have the lowest value. As the amount of lotus leaf and lotus root powder increased, hardness increased. Springiness showed the same tendency, but cohesiveness of the control revealed the lowest value. The structure of the cake crumb by SEM, revealed that the crumb cells and grains of the experimental cakes were opened and coarse, as the amount of lotus leaf and lotus root powders increased. In a sensory evaluation, sponge cakes containing lotus root powder were preferred rather than those with lotus leaf powder. As a result, good sponge cakes were prepared by adding 4% lotus leaf powder or 8% lotus root powder.

• Korean Journal of Food Science and Technology
• /
• v.37 no.5
• /
• pp.736-740
• /
• 2005

As an alternative of yeast, various concentrations to prepare hypo-allergenic bread (HAB). Addition of sodium bicarbonate increased $CO_2$ emission, but at higher than 2.0% caused bitter taste compared to other mixtures. Addition of sucrose significantly increased $CO_2$ emission. HABs 7 ($NaHCO_3$ 2.0g+sucrose 0.63 g) and 8 ($NaHCO_3$ 2.0g+sucrose 1.0g) showed higher grain and color scores. HAB 5 ($NaHCO_3$ 1.5g+sucrose 1.0g) and 6 ($NaHCO_3$ 1.5g+sucrose 2.0g) gave higher aroma and taste scores. HAB 5 showed significantly higher overall acceptability (p<0.05) score than others, whereas HABs 7 and 8, regardless of high external sensory qualities, showed lower overall acceptabilities than HAB 5 due to bitter taste. Prototypical HAB was obtained using wheat flour (100g) and water (62mL) incubated at $37^{\circ}C$ for 4 hr for treatment of b.p pretense (100mg) before adding sodium bicarbonate (1.5%), sucrose (1.0%), NaCl (1.0%), and citric acid (1.0%).

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.11
• /
• pp.1716-1723
• /
• 2014

This study was designed to examine the change in physical properties of extruded brown rice-vegetable mix at different pregelatinized brown rice contents and $CO_2$ gas injection. Moisture content, screw speed and die temperature were fixed to 30%, 100 rpm and 60, respectively. $CO_2$ gas injection was adjusted to 0, 300, 600, and 800 mL/min. The content of vegetables (carrot, pumpkin, kale and Angelica keiskei) mix was fixed 5%. Pregelatinized and raw brown rice powder were blended as the ratio of 0/95, 30/65 and 50/45. Specific mechanical energy input decreased as pregelatinized brown rice ratio increased. Expansion index increased and the size and number of pores increased but density decreased with the increasing in $CO_2$ gas injection. Gelatinization degree increased as $CO_2$ gas injection increased. In conclusion, cold extrusion with $CO_2$ gas injection at $60^{\circ}C$ die temperature could be applied for Saengsik (uncooked food) making.

• Korean Journal of Food Science and Technology
• /
• v.49 no.2
• /
• pp.151-157
• /
• 2017

The physicochemical properties of rice flours and quality characteristics of rice cupcake were investigated using the domestic rice varieties Goami, Hanareum, Hanmaeum, Deuraechan, Seolgaeng, and Haiami. Protein and amylose contents were highest in. The final and setback viscosities of Haiami, Hanmaeum, Deuraechan, and Hanareum were higher than those of Goami and Seolgaeng. The specific volume of rice cupcakes was lower with Goami and Haiami than with the others. Seolgaeng cupcake had a dented surface and irregular air pockets, while the Hanareum cupcake was well shaped and had uniform air pockets. The hardness, springiness, and chewiness of Goami and Haiami cupcakes were higher than those of the others, while adhesiveness was observed only in Seolgaeng cupcake. The overall preferences scores of rice cupcakes prepared from Hanareum, Hanmaeum and Deuraechan were higher than for the other cupcakes (p<0.05). These results suggested that amylose content, and final and setback viscosities of rice flour are very important factors in rice cupcakes.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.42 no.6
• /
• pp.957-963
• /
• 2013

This study evaluated the quality characteristics of muffins prepared with different amounts (0%, 4%, 8%, or 12%) of apricot powder. The moisture content was higher in groups containing 8% and 12% apricot powder. The specific volume of muffins decreased as the amount of apricot powder increased. The lightness value was lower in groups containing apricot powder, with redness and yellowness values increasing with increasing amounts of apricot powder. Rheology tests showed no significant differences in hardness, springiness, and cohesiveness between control muffins and muffins with apricot added. Scanning electron microscopy showed that the number and size of air cells decreased with increasing levels of apricot powder. The substitution of wheat flour with apricot powder yielded muffins with a higher DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging activity and total polyphenol content. Consumer acceptance tests revealed no significant differences in appearance, smell, and texture between muffin samples, but the taste and overall acceptability scores were lowest for muffins with 12% apricot added. Therefore, up to 8% apricot powder can be incorporated into muffins to meet the sensory quality and functional needs of the consumer.

• Korean Journal of Food Science and Technology
• /
• v.51 no.2
• /
• pp.127-132
• /
• 2019

This study investigated the quality of Jeungpyun based on variety, milling method and fermentation time. Rice flour (wet-milled Samkwang and dry-milled Seolgaeng) was used for these experiments. The expansion ratios of wet-milled Samkwang and dry-milled Seolgaeng after 6 h of fermentation showed similar values of 160.66 and 159.52%, respectively, while the specific volume was found to be 1.12 mL/g for both. Hardness values of 475.57 g in dry-milled Seolgaeng and 550.40 g in wet-milled Samkwang were determined to be the lowest values after 6 h of fermentation. Numerous pores were found in wet-milled Samkwang, whereas large-sized pores were found in dry-milled Seolgaeng. Thus, these results show no significant difference between the quality of Jeungpyun produced using dry-milled Seolgaeng or wet-milled Samkwang rice flours. However, dry- milled Seolgaeng without the wet-milled process is considered more suitable for Jeungpyun production.

• Electrical & Electronic Materials
• /
• v.9 no.6
• /
• pp.605-615
• /
• 1996

In this paper, the effect of alkaline oxide addition such as Li$_{2}$O and Na$_{2}$O on the microstructure and humidity sensitivity of V$_{2}$O$_{5}$(2 mol%)-doped TiO$_{2}$(98 mol%) was investigated as a function of amount (0, 1, 2, 5, 10 mol%) of Li$_{2}$O and Na$_{2}$O additives. The pores in the alkaline free sample were distributed mostly in the range between 0.16 and 1.0.mu.m in diameter and its porosity was 23.29%. Li$_{2}$O caused grain overgrowth and reduced the porosity with a narrow distribution of the pore size, leading to poor humidity sensitivity. Na$_{2}$O helped to enlarge the distribution of the pore size through the formation of small soluble phases. The pore sizes of the sample containing Na$_{2}$O 2mol% were distributed mostly in the range between 1.0 and 2.5.mu.m in diameter and its porosity and intrusion volume of mercury were 31.13 % and 0.1155 mL/g respectively, which consequently improved the humidity sensing characteristics such as the sensitivity and temperature-stability. Especially, the addition of 2mol% of Na$_{2}$O improved the humidity-sensing characteristics such as sensitivity and linearity in the whole range between 30 and 90 %RH (Percentage Relative Humidity)y)