• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.7
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• pp.635-643
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• 2017

The purpose of this study is to investigate the influence of the cold reduction rate and an ultrasonic fatigue test (UFT) on the fatigue behaviors of STS 304L. The tensile strength, yield strength, hardness value and fatigue limit in the UFT fatigue test linearly increased as thickness decreased from 1.5 mm to 1.1 mm, as the cold reduction rate of STS 304L increased. As a result of the UFT fatigue test (R = -1) of four specimens, the fatigue limit of the S-N curve formed a knee point in the region of $10^6$, and the 2nd fatigue limit caused by giga cycle fatigue did not appeared. In the case of t = 1.1 mm, the highest fatigue limit was 345 MPa, which was 64.3% higher than the original material (t = 1.5 mm). As a result of the UFT fatigue test of STS 304L, many small surface cracks occurred, grown, coalesced while tearing.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.345-356
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• 1994

Each of the three cationized compounds synthesized previously, poly(OMA-co-DAMA)[PODC], poly(DMA-co-DAMA)[PDDC] and poly(EMA-co-DAMA)[PEDC] was blended with waxes, emulsifiers and cationized fatty carbamide(ODTCC) synthesized in this study for the preparation of some durable softening water-repellenting agents, PODCW, PDDCW and PEDCW. The results of washability, tearing strength, crease recovery and contact angle of the cotton fabrics treated with PODCW, PDDCW and PEDCW with and without textile finishing resin, showed remarkable improvement of the physical properties. Rating of water repellency of cotton fabric treated with PODCW was 80, but those treated with PDDCW and PEDCW were not high enough to use in industry. Proper curing temperature of the synthesized water-repelleting agents was $140^{\circ}C$; proper using concentration was 3wt%; sodium acetate was the best catalyst for water-repellenting agents among the used, and proper concentration was 0.6wt%. From the results of reaction mechanism of cellulosic fiber with water-repellenting agent and washability of the fibers treated with water-repellenting agents the prepared water-repellenting agent proved to be durable. Surface structures of cotton fabrics treated with water-repellenting agent were investigated by SEM.

• Korean Journal of Food Science and Technology
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• v.46 no.6
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• pp.682-688
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• 2014

The in vitro digestibility and molecular and crystalline structures of rice starches (Seilmi, Dasan1, and Segoami) with differing amylose content were investigated. Segoami had the highest amylose content (30.9%), whereas Dasan1 had the lowest amylose content (21.2%). The molecular weight ($\bar{M}_w$) of amylose and amylopectin in Segoami was much lower than that of the other two rice starches. Segoami had the highest proportion (8.7%) of amylopectin short branch chains (DP 6-12) and the lowest proportion of B1 chains (DP 13-24). The relative crystallinity, intensity ratio of $1047-1022cm^{-1}$ (1047/1022) and gelatinization enthalpy followed the order: Segoami>Seilmi~Dasan1. Segoami showed substantially low pasting viscosity. Rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) contents showed the highest value in Seilmi, Dasan1, and Segoami, respectively. The expected glycemic index (eGI) of Segoami was lower than that of the other two rice starches. Overall results suggested that the digestibility of rice starch could be highly influenced by their molecular and crystalline structure.

• Archives of design research
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• v.12 no.1
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• pp.27-36
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• 1999

The history of the Korean textile industry is not very long. Its growth only began from the early 1960's. Since then, its production scale and export volume have enpanded enormosly. The textile industry made a great contribution to Korea's sustained economic growth over the past three decades. While expanding rapidly, however, the Korean textile industry went through many difficulties and problems. To survive through interational competition, the textile produce were manufactured on a subcontract basis and prices were set at too low levels. Consequently the profit margins were very small. To meet international competition for the 21st century, the textile industry requires restructuring and a drastic progress has to be made in textile design and technology. To become internationally competitive, the education system for textile design must be improved. The textile schools must be equipped with better technology and facilities so that students may have a hands-on experience and acquire application skills quickly and effectively. Also students should be given an opportunity to work in the industry as an intern. In order to make all these possible, both the government and the industry must be fully supportive. Textile designing can be considered a cultural reflection. This implies that to develop the textile industry requires the elevation of the people's mind and culture. To improve textile technology and to elevate the standard of textile design, the government and the textile schools must make continued effort together.

• Korean Journal of Food Science and Technology
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• v.47 no.3
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• pp.321-327
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• 2015

The optimal condition for preparation of powdered calcium acetate (LCCA) which has high solubility, from calcined powder (LCCP) of the littleneck clam shell by response surface methodology (RSM) was examined. Increased molar ratio of LCCP led to reduced solubility, yield, color values, and overall quality. The critical values of multiple response optimization of independent variables were 2.57 M of acetic acid and 1.57 M of LCCP. The actual values (pH 7.0, 96.1% for solubility, and 220.9% for yield) under the optimized condition were similar to the predicted values. LCCA showed strong buffering capacity between pH 4.89 and 4.92 on addition of ~2 mL of 1 N HCl. The calcium content and solubility of LCCA were 21.9-23.0 g/100 g and 96.1-100.1%, respectively. The FT-IR and XRD patterns of LCCA were identified as calcium acetate monohydrate, and FESEM images revealed an irregular and rod-like microstructure.

• Korean Journal of Food Science and Technology
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• v.52 no.3
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• pp.220-225
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• 2020

In this study, we investigated the starch characteristics of foxtail millet (FM) and sorghum (SG) cultivars grown in Korea. The amylose contents were 29.42 and 6.42% in the Daname and Samdachal FM cultivars, and 9.09 and 11.11% in the Nampungchal and Sodamchal SG cultivars, respectively. The amylopectin polymerization analysis showed that the highest degree of polymerization (DP) was in the range of DP13-24 for all samples, at approximately 60%. The resistant starch content was very low (<0.10%) among the FM and SG cultivars. The starch gelatinization analysis showed low setback values in the Samdachal and Nampungchal cultivars. The gelatinization enthalpy, calculated based on an endothermic reaction, did not differ significantly between the SG cultivars but was significantly higher in the Samdachal FM cultivars than in the Daname FM cultivars. The results of this study might be used as basic data for the development of FM and SG products.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.10-19
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• 2014

Corrugated steel plates are made by fabricating thin steel plates to have trapezoidal or sinusoidal corrugation, and the corrugated plates are able to maintain high out-of-plane rigidity even when they are used instead of thick flat plates. Also, corrugated steel plates have almost no axial rigidity due to the accordion effect. Thus, if they are applied to the webs of plate girders, designing can be easily conducted so that the webs bear only shear stresses. However, unlike flat plates, the shear buckling of corrugated steel plates has very complex characteristics where buckling occurs due to the interaction of local and global buckling, besides local buckling and global buckling. For the investigation of the cause and characteristics of this interactive buckling, studies on sinusoidal corrugated steel plates are fewer than studies on trapezoidal corrugated steel plates. Therefore, in this study, the shear buckling characteristics of sinusoidal corrugated steel plates and the occurrence pattern of interactive buckling were investigated. For the calculation of shear buckling strength, a finite element program was used, and the analysis results were compared with the exact solution. In addition, the characteristics of buckling stress change and the change of buckling mode shape depending on corrugation thickness and shape parameter were analyzed, and by comparing these results with the results of a theoretical equation, the timing of buckling mode change was analyzed.

• Korean Journal of Food Science and Technology
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• v.35 no.3
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• pp.417-422
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• 2003

The onions are considered to be a favorable functional source of beverage because they contain much sugar and various nutrients, and they are juicy vegetable. Recently, consumers have a new trend to take functional foods with health benefits. To meet this need, this study was the basic research to establish a manufacturing process of functional onion beverage by glucose oxidase. Glucose oxidase catalyzes reaction of glucose oxidation and makes generation of gluconic acid. Kinetics of the reaction was also investigated, and maximum glucose consumption rate $(V_{max})$ of $26.1{\times}10^{-2}\;g/L{\cdot}min$ and $K_m$ of 5.84 g/L were obtained. Optimum conditions were obtained when the glucose oxidase catalyzed reaction was carried out at temperature of $25^{\circ}C$, agitation rate of 450 rpm and aeration rate of 4 vvm in a 2.5 L jar fermentor. Finally, the enzyme reactor was 10-times scaled up and a similar glucose oxidation performance was achieved in the scaled-up reactor.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.7-14
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• 2003

Physico-chemical and sensory characteristics of six dongchimi cultivars were evaluated. Moisture and sugar contents were 94.2% and $4.30^{\circ}Brix$ for three spring radish cultivars, while 92.9% and $7.30^{\circ}Brix$ for three autumn ones. pH $(5.7{\sim}6.1)$ and acidity $(0.09{\sim}0.12%)$ did not show significant differences among cultivars. pH decreased steadily up to 21 days to reach optimum pH of 4.0. The maximum number of total lactic acid bacteria, $10^8{\sim}10^9\;CFU/mL$, was reached at pH 4.0. The final acidity of spring radishes was lower than that of autumn ones, and was proportional to the sugar content of the radishes. The firmness of spring radish decreased rapidly compared to the autumn ones. Cheongbok was found suitable for dongchimi, because its firmness level was maintained around $165.0{\times}10^3\;N/m^2$ at 35 days. Sensory evaluation revealed 96371 among spring radishes and cheongbok among autumn radishes scored high in firmness, chewiness, flavor, and overall acceptance. These results suggest that autumn radishes are suitable for dongchimi fermentation with cheongbok being the best among the cultivars.

• Food Science and Preservation
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• v.22 no.6
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• pp.859-866
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• 2015

The purpose of this study was to develop a supplemental healthy food that can help prevent high blood pressure-related diseases caused due to the excessive consumption of sodium in salt. This was achieved by using ion-displacement techniques to produce mineral salt with lower sodium content by using fermented brown rice by-products rich in minerals. Mineral salt containing 2019.2 mg/100 g of potassium, 678.5 mg/100 g of magnesium, 48.7 mg/100 g of calcium, and 19.5 mg/100 g of sodium was obtained by fermenting brown rice by-products to create a culture medium for the mineral salt. Mineral salt containing 1769.7 mg/100 g of potassium, 573.6 mg/100 g of magnesium, 35.3 mg/100 g of calcium, and 19.5 mg/100 g of sodium was obtained by filtering and refining the by-product extract of fermented brown rice. The results showed that when the stream velocity of the instrument used for electrolysis was 200 mL/min and the current and the concentration of the reactive liquid in the purified water chamber were higher, the effect of electrolysis was greater. Ion hot water extraction of the fermented brown rice by-products improved by up to 95% and was collected as purified water within 90 min of the reaction time. Chloride ions with pH 7.4 were produced by mixing sodium hydroxide in a purified saline water chamber with electro-analyzed water. The salt produced in this study contained low sodium, 5.7~30%, as compared to 40% sodium content of the normal salt.