• Title/Summary/Keyword: SiC powder

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The Recycling of Inorganic Industrial Waste in Cement Industry (시멘트산업에서 무기질 산업 폐·부산물의 재활용)

  • Kang, S.K.;Nam, K.U.;Seo, H.N.;Kim, N.J.;Min, K.S.;Chung, H.S.;Oh, H.K.
    • Clean Technology
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    • v.6 no.1
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    • pp.61-69
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    • 2000
  • In this study, generation process and properties of inorganic industrial waste which can be used in cement industry were investigated. The scheme of recycling to use the selected waste as raw materials, mineralizer and flux, admixture and raw materials for special cement was decided and then various experiments were carried out. The experimental results were as follows ; In the use of industrial waste as raw materials, ferrous materials could be substituted by Cu-slag, Zn-slag, electric arc furnace or convertor furnace slag etc., and a siliceous material could be substituted by sand from cast-iron industry. By-products from sugar or fertilizer industry, which has $CaF_2$ as the main component, and jarosite from Zn refinery enabled clinker phases to be formed at lower temperature by $100{\sim}150^{\circ}C$. Adding Cu slag and STS sludge in proper proportion to cement improved properties of cement. Fly ash and limestone powder as admixture had the same effect on cement. As a raw material for special cement, aluminium waste sludge could be used in making ultra early strength cement, which had the compressive strength of $300kg/cm^2$ within 2hours. And two different ashes from municipal incinerator could be raw materials of the cement which was mainly composed of $C_3S$ and $C_{11}A_7{\cdot}CaCl_2$ as clinker phases.

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Fermentation Process for Odor Removal of Oyster (Crassostrea gigas) Hydrolysate and Its Properties (이취 제거를 위한 굴 가수분해물의 발효공정과 제품의 특성)

  • Lee, Su-Seon;Park, Si-Hyang;Kim, Hyeun-A;Choi, Yeung-Joon
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.45 no.4
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    • pp.542-550
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    • 2016
  • This study was carried out to investigate the optimal processing conditions for odor removal and maximal antioxidant effects of oyster (Crassostrea gigas) hydrolysate. The optimal hydrolysis conditions were 3.3% neutrase as the protease, $50^{\circ}C$ as the hydrolysis temperature, and 8.3 h as the hydrolysis time. Fish odor of enzymatic oyster hydrolysate was greatly reduced during Saccharomyces cerevisiae fermentation at $24^{\circ}C$ with 0.5% glucose. The protein content of the fermentation product from oyster hydrolysate powder was 25.7%, which contained the major amino acids Glu, Asp, Lys, Arg, Gly, and Ala, whereas Leu, Ala, Phe, Val, and Tau were abundant free amino acids. The important minor minerals were Zn and Fe. Toxicity against Chang cells was not observed in the fermentation product from the oyster hydrolysate up to $200{\mu}g/mL$. The results suggest that fermentation with S. cerevisiae could reduce the fish odor of enzymatic oyster hydrolysate. The hydrolysate has potential application as a food ingredients and nutraceutical.

A Study on Properties of Domestic Fly Ash and Utilization as an Insulation material (국산 Fly Ash의 특성 및 단열재로의 이용에 관한 연구)

  • 박금철;임태영
    • Journal of the Korean Ceramic Society
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    • v.20 no.2
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    • pp.135-146
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    • 1983
  • This study is to investigate the properties of domestic fly ash for utilization as data in regard to fly ash which is by-product of domestic coal powder plants and the possibility of utilization as insulation material of domestic fly ash. Composition refractoriness size distribution density contents of hollow particles and crystalline phase were examined as the properties of domestic fly ash. As to the fired test pieces of fly ash by itself that varied contents of hollow particles with four kinds and of the fly ash-clay-saw dust system linear shrinkage bulk density app. porosity compressive strength thermal conductivity and structures were investigated for the possibility of utilization as an insulation material. The results are as follows : 1. The properties of the fly ash I) The constituent particle of the fly ash is spherical and it contains not a few hollow particles (floats by water 0.30-0.50 floats by $ZnCl_2$ aq.(SpG=1.71) 6.97-16.72%). ii) The chemical compositions of fly ash are $SiO_243.9-54.1%$ , $Al_2O_321.0-30.7%$ Ig loss is 7.4-24.1% and the principal of Ig loss is unburned carbon. iii) Fly ash was not suitable to use for mortar and concrete mixture because Ig. loss value is higher than 5% 2. Utilization as insulation material I) The test pieces of original fly ash floats by water floats by ZnCl2 aq(SpG=1.71) p, p t by ZnCl2 aq.(SpG=1.71) that were fired at 110$0^{\circ}C$ represented 0.11-0.18 kcal/mh$^{\circ}$ C as thermal conductivity value. ii) The test pieces which (76.5-85.5) wt% fly ash-(8.5, 9.5) wt% clay-(5.0-15.0) wt% saw dust system(68.0-72.0) wt% fly ash -(17.0-18.0)wt% clay-(10.0-15.0) wt% saw dust system and 59.5 wt% fly ash-25.5 wt% clay-15.0wt% saw dust system were fired at 110$0^{\circ}C$ the thermal conductivity was less than 0.1Kcal/mh$^{\circ}$ C. iii) In view of thermal conductivity and economic aspect insulation materials which added saw dust as blowing agent and clay as inorganic binder are better than that of fly ash as it is or separated hollow fly ash particles. iv) When the saw dust contents increased in the (59.5-90.0) wt% saw dust system and when amount of clay de-creased and firing temperature decreased under the condition of equal addition of saw dust app. porosity increased but bulk density compressive strength and thermal conductivity decreased.

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Synthesis of Zeolites ZSM-5 and ZSM-48 from Gasification Ashes of Agricultural Wastes

  • Lin, Kuen-Song;Lin, Wen-Chiang;Chitsan Lin
    • Proceedings of the IEEK Conference
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    • 2001.10a
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    • pp.610-615
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    • 2001
  • Over 800 thousand tons per year (TPY) agricultural biowastes, such as sugar cane bagasse, sugarcane leaf, rice straw, rice husk and corn leaf, are produced in Taiwan. These biomasses are the major types of agricultural wastes and are abundantly available. However, these biowastes cause disposal and landfill problems. Ossification ashes of the agricultural biowastes containing 70-95 % amorphous silica would make the utilization system of agricultural biowaste ashes become highly economically and environmentally attractive. Experimentally, high crystallinity (99%$^{+}$) zeolites ZSM-5 and ZSM-48 synthesized from the reaction mixtures containing a silica source from ashes of these biowastes gasification were investigated. Tetrapropylammonium bromide (TPABr) and 1,6-diamino-hexane (C$_{6}$ DN) were used as structure-directing agents in syntheses of ZSM-5 and ZSM-48, respectively. X-ray powder diffraction (XRD) and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDX) data indicated that ZSM-5 or ZSM-48 with a high crystallinity can be obtained within 48 hours of crystallization in the high pressure (15-20 atm) autoclave at 393-473 K. The Si/Al ratios of synthetic zeolite products were determined by X-ray fluorescence (XRF) and induced couple plasma/mass spectroscopy (ICP/MS). It was observed that the ZSM-5 crystals a.e composed of hexagonal rod-shaped crystals with typically 8-13 пm in size by SEM. In addition, ZSM-48 crystalline materials are composed of spherical aggregates of needle-shaped or rod-like crystals with typically 2-3 пm in diameter and 6-8 пm in length.h.

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Deposition of Polytetrafluoroethylene Thin Films by IR-pulsed Laser Ablation (Nd:YAG 레이저에 의한 폴리테트라플루오르에틸렌 박막 증착)

  • Park Hoon;Seo Yu-Suk;Hong Jin-Soo;Chae Hee-Baik
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.6 no.1
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    • pp.58-63
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    • 2005
  • PTFE (polytetrafluoroethylene) thin films were prepared from the pellets of the graphite doped PTFE via pulsed laser ablation with 1064 nm Nd:YAG laser. The graphite powder converts the absorbed photon energy into thermal energy which is transmitted to nearby PTFE. The PTFE is decomposed by thermal process. The deposited films were transparent and crystalline. SEM (scanning electron microscopy) and AFM (atomic force microscopy) analyses indicated that the film surface morphology changed to fibrous structure with increasing thickness. The fluorine to carbon ratios of the film were 1.7 and molecular axis was parallel with (100) Si-wafer substrate. These results obtained by XPS (X-ray photoelectron spectroscopy), FTIR (fourier transform infrared spectroscopy) and XRD (X-ray diffraction).

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Measurement of Porcelain Shrinkage After Firing Using the Phase-Shifting Profilometry (위상이동 형상측정법을 이용한 도재 소성시의 도재 수축률의 측정)

  • Lee, Cheong-Hee
    • The Journal of Korean Academy of Prosthodontics
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    • v.37 no.6
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    • pp.800-808
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    • 1999
  • To compare several porcelains made by various manufacturers in shrinkage after firing and investigate the effect of condensation on shrinkage, specimens were prepared and the volume of each body was measured by the phase-shifting profilometry. Baseplate wax was cut by $2.5cm{\times}2cm$ and cast in nonprecious metal(Verabond, U.S.A.), then any surfaces of specimens were abrased and polished on the SiC abrasing papers, preparing 120 specimens. Specimens were divided into six groups according to the porcelain used, and the porcelain used in each group were as follows. Group I : Ceramco dentin porcelain Group B : Creation dentin porcelain Group III : Creation margin porcelain Group IV : Vintage margin porcelain Group V : Vita dentin porcelain Group VI : Vintage dentin porcelain Porcelain was built up on the metal plates using a small spoon and then solution matching to each porcelain was added. The six groups are subdivided into a and b. In subgroup a, only excessive solution was absorbed with tissue and in subgroup b, porcelain was condensed sufficiently. When build-up was completed, the shape was measured using the phase-shifting profilometry. After that, specimens were fired in the furnace programed for each porcelain and then their changed shape were measured again. Using the difference between the two above measurements, the ratio of shrinkage was calculated. Obtained results were as follows ; 1. Regardless of condensation, the volume of fired specimens were not different significantly between the two subgroups a and b in the same group. 2. The ratios of shrinkage were significantly higher in the groups porcelain built-up was condensed than in the groups not condensed 3. The ratios of shrinkage were in the range of 36.81-27.19% in the groups porcelain built up was condensed and 44.52-37.54% in the other groups not condensed.

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Preparation and Keeping Quality of Snacks Prepared from Rice Oryza sativa and Dried Oyster Crassostrea gigas (마른 굴(Crassostrea gigas) 첨가 쌀(Oryza sativa) Collet을 이용한 Snack의 제조 및 저장안정성)

  • Kang, Kyung-Hun;Je, Hae-Soo;Park, Si-Young;Kang, Young-Mi;Lee, Jae-Dong;Seoung, Tae-Jong;Park, Jin-Hyo;Kim, Jeong-Gyun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.49 no.6
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    • pp.750-757
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    • 2016
  • This study investigated the quality, sensory characteristics and commercial potential of a rice snack prepared with dried oyster. Mild and spicy versions of the snack were produced using an oil coating and a mixed seasoning powder coating, respectively. The approximate compositions of the mild snack and spicy snack were 5.13% and 4.78% moisture, 8.92% and 8.94% crude proteins, 17.58% and 20.35% crude lipids, 1.88% and 1.87% ash, and 2% and 1.8% salt, with water activity values of 0.20 and 0.18 and a pH of 6.11 and 6.10, respectively. The color of the mild snack was lighter with more yellow and less red compared with the spicy snack. Thiobarbituric acid levels increased slightly, and hardness decreased slightly during storage at $27{\pm}2^{\circ}C$. The sensory score of the spicy snack was slightly higher than that of the mild snack. These results suggest that the spicy snack might have more commercial potential than that of the mild snack according to its higher sensory test score.

Fabrication of High Strength Transparent Bulletproof Materials by Ion Exchanged Borosilicate Glass (보로실리케이트 유리의 이온교환에 의한 고강도 투명방탄소재의 제조)

  • Kim, Young-Hwan;Shim, Gyu-In;Lim, Jae-Min;Choi, Se-Young
    • Journal of the Korea Institute of Military Science and Technology
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    • v.13 no.6
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    • pp.1121-1126
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    • 2010
  • Borosilicate glass (81% $SiO_2$-2% $Al_2O_3$-13% $B_2O_3$-4% $Na_2O_3$) was prepared, and the glass was ion exchanged in $KNO_3$ powder containing different temperature and time. The $K^+-Na^+$ ion exchange takes place at the glass surface and creates compressed stress, which raise the mechanical strength of the glass. The depth profile of $Na^+$ and $K^+$ was observed by electron probe micro analyzer. With the increasing heat-treatment time from 0min to 20min, the depth profile was increased from 17.1um to 29.4um, but mechanical properties were decreased. It was also found out that excessive heat treatment brings stress relaxation. The Vickers hardness, Fracture Toughness and bending strength of ion exchanged samples at $570^{\circ}C$ for 10min were $821.8H_v$, $1.3404MPa{\cdot}m^{1/2}$, and 953MPa, which is about 120%, 180%, and 450% higher than parent borosilicate glass, respectively. Transmittance was analyzed by UV-VIS-NIR spectrophotometer. Transmittance of ion exchanged borosilicate glass was decreased slightly at visible-range. It can be expected that transparent bulletproof materials in more light-weight and thinner by ion exchanged borosilicate glass.

A Study of Iron Pot Casting and Bellows Technology (토제 거푸집 무쇠솥 주조와 불미기술 연구)

  • Yun, Yonghyun;Doh, Jungmann;Jeong, Yeongsang
    • Korean Journal of Heritage: History & Science
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    • v.53 no.2
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    • pp.4-23
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    • 2020
  • The purpose of this study was to explore the diversity of Korea's iron casting technology and to examine various casting methods. The study involved a literature review, analysis of artifacts, local investigation of production tools and technology, and scientific analysis of casting and cast materials. Bellows technology, or Bulmi technology, is a form of iron casting technology that uses bellows to melt cast iron before the molten iron is poured into a clay cast. This technology, handed down only in Jeju Island, relies on use of a clay cast instead of the sand cast that is more common in mainland Korea. Casting methods for cast iron pots can be broadly divided into two: sand mold casting and porcelain casting. The former uses a sand cast made from mixing seokbire (clay mixed with soft stones), sand and clay, while the latter uses a clay cast, formed by mixing clay with rice straw and reed. The five steps in the sand mold casting method for iron pot are cast making, filling, melting iron into molten iron, pouring the molten iron into the cast mold, and refining the final product. The six steps in the porcelain clay casting method are cast making, cast firing, spreading jilmeok, melting iron into molten iron, pouring the molten iron, and refining the final product. The two casting methods differ in terms of materials, cast firing, and spreading of jilmeok. This study provided insight into Korea's unique iron casting technology by examining the scientific principles behind the materials and tools used in each stage of iron pot casting: collecting and kneading mud, producing a cast, biscuit firing, hwajeokmosal (building sand on the heated cast) and spreading jilmeok, drying and biyaljil (spreading jilmeok evenly on the cast), hapjang (combining two half-sized casts to make one complete cast), producing a smelting furnace, roasting twice, smelting, pouring molten iron into a cast, and refining the final product. Scientific analysis of the final product and materials involved in porcelain clay casting showed that the main components were mud and sand (SiO2, Al2O3, and Fe2O3). The release agent was found to be graphite, containing SiO2, Al2O3, Fe2O3, and K2O. The completed cast iron pot had the structure of white cast iron, comprised of cementite (Fe3C) and pearlite (a layered structure of ferrite and cementite).

The research about the physical properties and flexural strength changed by Low Temperature Degradation of TZP monolithic all-ceramic crown block to make bio-prosthetic dentistry (치과용 생체보철물 제작을 위한 TZP 단일구조 전부도재관 블럭의 물성과 저온열화 후 굴곡강도에 관한 연구)

  • Lee, Jong-Hwa;Park, Chun-Man;Song, Jae-Sang;Lim, Si-Duk;Kim, Jae-Do;Kim, Byung-Sik;Hwang, In-Whan;Lee, Sung-Kuk
    • Journal of Technologic Dentistry
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    • v.34 no.2
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    • pp.83-93
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    • 2012
  • Purpose: The objective of this study is to find out physical properties and the flexural strength changed by the low temperature degradation of the block which is needed to make bio-prosthetic dentistry which is better than feldspar affiliated ceramic made by building up ceramic powder and also to apply this to the clinical use of zirconia monolithic all-ceramic crown. Methods: Flexural strength of each sample was evaluated before and after the Low Temperature Degradation, and physical properties of the Tetra Zirconia Block containing 3mol % was evaluated as well. The average and standard deviation of each experimental group were came out of the evaluation. Statistical package for social science 18.0 was used for statistics. Results: The average density of the monolithic all-ceramic crown was $6.0280{\pm}0.0147g/cm$, the relative density was 99.01 %. When the sample was sintered at $1480^{\circ}C$ the diameter of average particle was $396.62{\pm}33.71nm$. All the samples had no monolithic peak after XRD evaluation but only had tetragonal peak. There were statistically significant differences in the result of flexural strength of the samples evaluated after and before the low temperature degradation, the flexural strength before the low temperature degradation was $1747.40{\ss}{\acute{A}}$, at the temperature of $130^{\circ}C$ the flexural strength after the low temperature degradation was 1063.99MPa (p<0.001). There was statistically significant difference in the result of strength of 1020.07MPa after the low temperature degradation at the temperature of $200^{\circ}C$ (p<0.001). Conclusion: The block which was made for this evaluation possesses such an excellent strength among dental restorative materials that it is thought to have no problems to use for tetragonal zirconia polycrystal.