• Journal of the Korean Ceramic Society
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• v.26 no.1
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• pp.51-58
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• 1989

Wear and wear transition mechanisms during sliding as a function of time in Al2O3 have been studied to understand the wear behaviour of brittle ceramic materials. Commercial Si3N4 ball was rotated against flat Al2O3 specimens which were hot pressed and polished using upto 1${\mu}{\textrm}{m}$ diamond paste. Paraffin oil was used as a lubricant. Experimental data show that wear of Al2O3 is separated into distinct two stages, i.e., initial stage of slow wear and final stage of rapid wear. Microstructural observations at worn surface show that wear occurs through grooving and grain pull-out in the initial and final stage respectively. TEM observations beneath the worn surfaces show that grain pull-out starts to occur by the propagation of grain boundary cracks induced by dislocation pile-up throughthe surface.

• Journal of Powder Materials
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• v.1 no.1
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• pp.27-34
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• 1994

Commercial pure iron powder and iron powder of coated 0.45% phosphorus were mixed with graphite powder in dry mixer to control carbon content from 0 wt% to 0.8 wt%. Mixed powder was pressed in the mould under the pressure of 510 MPa. Compacts were sintered at 118$0^{\circ}C$ for 40 min. in cracked ammonia gaseous atmosphere. Some of these sintered specimens were quenched in oil, and tempered in Ar gas. All of these specimens were investigated for microstructure, density and hardness in relation to coated phosphorus and carbon content. The results obtained were as follows: (1) The microstructure of the sintered speciments revealed that the amount of pearlite was increased with increasing C content but decreased by P-addition. (2) The P-addition affected the microstructure of pores in which the pore shape became round and its mean size was decreased by P-addition. (3) After tempering of sintered specimens the structure of pearlite was changed from fine structure to coarse one in P added specimen. (4) Hardness was higher in P added specimens.

• Journal of the Korean Society of Food Culture
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• v.26 no.1
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• pp.39-52
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• 2011

This study examined the types and cooking methods for dasik (traditional pressed sweet), as recorded in 16 old Joseon dynasty (1392-1909) studies. The ingredients used in dasik during the Joseon dynasty were categorized into cereal powders, tree fruits, flower powders, root clods, dry-fish beef powders, and vegetables. In the early, middle, and late eras of the Joseon dynasty, $1^{st}$ set (two, five, and 70 kinds of dasik), $2^{nd}$ set (two, four, and 16 kinds of dasik) were prepared using cereal powders, and during the middle and late eras of the Joseon dynasty one and 22 kinds of dasik were prepared using tree fruits. During the late eras of the Joseon dynasty, seven kinds of dasik were prepared using flower powders, 11 kinds of dasik were prepared using root clods, 12 kinds of dasik were prepared using dry-fish beef powders, and two kinds of dasik were prepared using vegetables. The frequency of the ingredients were in the order of Huek-im (黑荏), Hwang-yul (黃栗), Jin-mal (眞末), Song-wha (松花), and Nok-mal (菉末) during the Joseon dynasty. To prepare dasik, the ingredients were mixed with honey, soy sauce, sesame oil, pepper, and water or ground and shredded to prepare for pressing and for abstract dasik, respectively. The appearance and taste of dasik varied, thereby resulting in nutrient supplementation, as the types of ingredients increased throughout the Joseon dynasty. This observation may be associated with the commercial industrial development that prevailed during the late Joseon dynasty. Further investigation will be conducted on the recipes and ingredients recorded in these old studies to develop a standardized recipe for the globalization of dasik.

• Journal of the Korean Wood Science and Technology
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• v.48 no.2
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• pp.196-205
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• 2020

The purpose of this study was to investigate a method for improving the physical and mechanical properties of laminated board made from oil palm trunk (OPT). The effects of pretreating the lamina with heat-pressure and altering the lamina composition of the laminated board were investigated. The outer third of OPT in cross-section had high-density wood, while the underlying third had low to medium density. The hot press was applied to pretreat the lamina that had low to medium density. The lamina were 1.5 cm in thickness, 5 cm in width, and 65 cm in length. The hot press was applied at 2.94 MPa or 4.41 MPa at 150 ℃ for 60 minutes, and the target thickness of the lamina was 1 cm. The three layers of the laminated board samples were bonded with isocyanate adhesive at a glue spread of 300 g/㎡ and cold pressed at 0.98 MPa for 3 h. The laminated board samples were tested according to Japanese Agricultural Standard (JAS) 234-2003. The results showed that the densification of the inner lamina did not significantly affect the physical-mechanical properties of the laminated board produced. However, the laminated board made with high-density laminas for the outer layers fulfilled the JAS 234-2003 standard for the modulus of elasticity and the modulus of rupture.

• Korean Journal of Food Science and Technology
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• v.44 no.3
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• pp.269-273
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• 2012

The principal objective of this study was to estimate the benzo(a)pyrene contents in commercial vegetable oils available in the Korean market and to assess the effects of various processing steps for vegetable oils on the contents of benzo(a)pyrene. Benzo(a)pyrene content in the studied commercial vegetable oils, crude oils, and raw materials were found to be lower than the maximum levels of 2 ppb. In both refined and pressed oil, the benzo(a)pyrene contents can be reduced through refining steps. However, an evident increase of benzo(a)pyrene contents during both the expeller process for corn oil and the roasting process for sesame oil was observed. This result indicates that the processing procedure, particularly heat treatment and refining steps would be critical in managing the benzo(a)pyrene contents in vegetable oils.

• Microbiology and Biotechnology Letters
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• v.3 no.1
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• pp.41-48
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• 1975

The chemical components and quality of Takjoo mash were examined on the product brewed by the case of commercial amylase, Lactobacillus bulgaricus and the yeast. 1. Lactic acid was produced at the range of 917~1,350 mg per 100 ml of the mash brewed using wheat flour, corn flour, rice and pressed barley, while succinic acid was formed at the range of 6~32 mg per 100m1 of the mash. 2. Citric acid was formed at the concentration of 6.5mg per 100m1 of the mash on the use of pressed barley, and malic acid formed at the concentration of 1.7 mg and 1.4 mg per 100m1 of the mash respectively, on the use of wheat flour and corn flour. 3. No remarkable differences between the kind of raw materials and commercial amylases and compared with the mash brewed with Nurook were observed in the components of fusel oil formed in the mash. 4. Seventeen kinds of the amino acids of the mash brewed with commercial amylase, Lactobacillus and the yeast were detected and its content was 31mg per 100ml, which is less than that of the conventional takjoo, but the contents of glycine and alanine which pray as the component of seasoning in takjoo were sufficient.

• Food Science of Animal Resources
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• v.27 no.1
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• pp.8-15
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• 2007

Conjugated linoleic acid (CLA) was chemically synthesized using the alkaline isomerization method of com oil. CLA-TG was synthesized by reaction with sodium methoxide. Five different treatments were devised based on differences in the amount of CLA-TG added into the pressed han. for controls, 10% of pork back fat among the total component was only added without any CLA-TG. For the first treatment, 5% of CLA-TG among the lard component added into the press ham was replaced. For the 2nd, 3rd and 4th treatments, 10%, 15% and 20% of CLA-TG was respectively replaced. Pressed ham manufactured using CLA-TG was vacuum packaged and then stored for 1, 7, 14, 21 and 28 days at $4^{\circ}C$. Samples were analyzed for chemical composition, physico-chemical properties (pH, color), and texture characteristics. Typical chemical composition characteristics (moisture, crude protein, crude fat) were not significantly different between controls and CLA-TG treatment groups. Crude fat content of CLA-TG treatment groups was significantly lower than that of controls (p<0.05). pH values of controls was higher than that of CLA-TG treatment groups. The pH of control and CLA-TG treatment groups increased significantly as the storage period increased (p<0.05). Meat color (CIE $L^*,\;b^*$) of CLA-TG treatment groups was higher than that of controls. $a^*$ values were decreased by replacement of CLA-TG, but appeared to be unaffected by storage length. There was no significant difference in texture between controls and CLA-TG treatment groups. Based on these findings, we conclude that the physico-chemical properties and texture characteristics of manufactured pressed ham were not affected by CLA-TG addition. Also, our results indicate that high-quality pressed ham can be manufactured with CLA accumulation.

• Journal of the Korean Society of Food Culture
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• v.7 no.1
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• pp.43-54
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• 1992

To analyze reception dishes of Choson Dynasty, studied historic book ‘Youngjeob Dogam Younhyangsek Euigwae’ (1609, 1634, 1643 year) described feast dishes for Chinese envoy in Choson Dynasty. The results obtained from this study are as follows. 1. The feast dishes consisted of the first main feast dishes (下馬宴, 上馬宴), the second main feast dishes (翌日宴, 請宴 and etc) and the third main feast dishes (別茶啖). 2. 下馬宴, 上馬宴 were arranged in four kinds of tale, the first one called the main table, the second the right side table, the third the left side table, the fourth the confronting side table. Dishes of main table were oil and honey pastry and fruits. Dishes of the second table and the third table were oil and honey pastry, and small cake made of honey and rice with patterns pressed in it. Dishes of the fourth table were cooked vegetable, dried slices of meat seasoned with spices, cooked meat, and fried fish. In feast, Chinese envoy drank 11 cups (1609 year) and 5 cups (1634 year) of liquor. At the first cup they abalones soup, others in a small round table (初味), a small boiled meet (小膳) and a large boiled meat (大膳), at a second cup eat (二味), at third cup eat (三味)..., at eleventh cup, they eat (十一味) and fruits.

• Korean Journal of Food Science and Technology
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• v.49 no.3
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• pp.242-251
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• 2017

The purpose of this study was to investigate the anti-proliferative effect of methanolic extracts from Citrus junos (yuja) seeds and yuja seed oils against HT-29 human colon cancer cells and to identify the key compounds responsible for this effect. Extracts from yuja seeds, yuja seed oil prepared using hexane, and cold-pressed yuja seed oil were prepared using 60% methanol (ES, EHO, and ECO, respectively). The key compounds in the extracts were determined using HPLC-MS. Among the extracts, EHO and ECO inhibited proliferation of HT-29 cells. EHO and ECO were fractionated using preparative LC and the bioactive compounds were determined. Five of the fractions showed a significant anti-proliferative effect and the main compounds in the fractions were isopimpinellin, bergapten, and ichangensin. These compounds showed anti-proliferative effects on HT-29 cells when treated individually, and ichangensin showed the highest anti-proliferative activity. These results suggest that these compounds may be responsible for the anti-cancer effect of EHO and ECO.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 2000.06a
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• pp.195-214
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• 2000

The high-speed steel (shorten as HSS) consists of Fe and several kinds of transition metal carbides. The cutting tools or wear-resistant materials made from HSS experience relatively high thermal shock because a coolant such as water or oil is flowed over the surface of heated HSS. The purpose of this research is to increase the hardness, strength, fracture toughness and thermal shock resistance of HSS. A possible strategy is to incorporate a hard ceramic material with high strength in HSS matrix. This paper describes the processing, microstructure and mechanical properties of the oriented unidirectional mullite fiber/HSS composite. The unidirectional mullite fibers of 10${\mu}{\textrm}{m}$ diameter were dispersed by the ultrasonic irradiation of 38 kHz in an ethylenglycol suspension containing HSS powder of 11${\mu}{\textrm}{m}$ median size. The dried green composites with 4-68 vol% fibers were hot-pressed for 2h at 100$0^{\circ}C$ in Ar atmosphere under a pressure of 39 MPa. The higher density was achieved in the composite with a lower content of fibers. The oriented unidirectional fibers were well dispersed in the HSS matrix. The average distance between the center of fibers in the cross section was close to the value calculated from the fiber fraction. No reaction occurred at the interfaces between HSS and mullite fibers in the composites. The composite with 13.6 vol% fibers showed 100 MPa of four point flexural strength at room temperature. The thermal expansion of composite with heating was influenced by the orientation of mullite fibers.