• Title/Summary/Keyword: 수적층

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Effect of the Particle Size and Unburned Carbon Content on the Separation Efficiency of Fly ash in the Countercurrent Column Flotation (向流컬럼浮選機에서 石炭灰의 크기 및 未燃炭素 含量이 分離特性에 미치는 영향)

  • 이정은;이재근
    • Resources Recycling
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    • v.9 no.6
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    • pp.36-44
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    • 2000
  • Fly ash was composed of the unburned carbon and mineral particles. The former was able to attach on the bubbles, while the latter was not. Therefore, it was possible to separate the unburned carbon and the mineral from fly ash using the froth flotation process. This study was carried out to evaluate the separation efficiency as a function of the ny ash particle properties in the column flotation. Separation efficiency was analyzed for various size fraction of -38 fm,38~125 fm and 1125 W, and for various fly ash samples containing 7, 11, and 20 wt% unburned carbon. For the size fractions of -38 fm containing 7 wt% unburned carbon, separation efficiency was 86ft, whereas separation efficiency was found to be 74% for the size fraction of +125μm containing 20 wt% unburned carbon. The results indicated that separation efficiency increased with the decrease in the particle size and the unburned carbon content of the fly ash.

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Clonal Variation in Female Flowering of Larix leptolepis (낙엽송 클론의 암꽃 개화량 변이)

  • Kim, In-Sik;Kim, Jong-Han;Kang, Jin-Taek;Lee, Byung-Sil
    • Korean Journal of Plant Resources
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    • v.21 no.1
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    • pp.1-4
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    • 2008
  • The clonal variation in female flowering was studied in Larix leptolepis clone bank, consisting of 116 clones, for three years. The between-year variation was large; i.e. the percentage of flowering grafts and average number of flowering per graft were 28.467.2 and 9176, respectively. Differences in flowering abundance among clones were large and statistically significant in all the years studied. The variance of flowering abundance among clones was increased when flowering was poor. The average of broad-sense heritability of flowering abundance was 0.52. The genetic gain(%G) was estimated at 57.4% when the upper 30% clones were selected. The clonal stability of flowering abundance was compared using average number of flowering and coefficient of variance value of each clone. The clones such as Gyeonggi 9(29), Kangwon 37(137), Chungnam 6(46), Chungnam 14(414), R11, R8 showed abundant flowering and high stability.

Influence of Sodium Hypochorite & EDTA on the Microtensile Bond Strength of Ethanol Wet Bonding (Ethanol Wet Bonding에서 NaOCl과 EDTA가 결합강도에 미치는 영향)

  • Kim, Deok-Joong;Song, Yong-Beom;Park, Sang-Hee;Kim, Hyoung-Sun;Lee, Hye-Yoon;Yu, Mi-Kyung;Lee, Kwang-Won
    • Journal of Dental Rehabilitation and Applied Science
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    • v.29 no.1
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    • pp.37-44
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    • 2013
  • Sodium hypochlorite and ethylene diamine tetra acetic acid are substances usually used during endodontic treatment. Several studies found that the bonding was negated with certain irrigants and some of the used irrigants have demineralizing and chealating effects, so it was advocated to omit the etching step in etch and rinse adhesive systems. The purpose of this in vitro study was to evaluate the influence of NaOCl & EDTA on the bonding strength of ethanol wet bonding. Thirty human molars were selected and mesiodistally sectioned into halves, thus providing sixty specimens. The specimens were randomly assigned to 4 groups(n=15) according to the irrigant regimen used : (1) irrigated with distilled water for 10min (control); (2) irrigated with 5.25% NaOCl(10min), flushed with 5.25% NaOCl(1min) (3) irrigated with 5.25% NaOCl, flushed with 17% EDTA (4) irrigated with 5.25% NaOCl, flushed with 17% EDTA. Each group was acid-etched with 37% phosphoric acid(except group 4) and had their dentin surfaces dehydrated with ethanol solutions : 50%, 70%, 80%, 95%, 3x100%, 30s for each application. After dehydration, a primer( 50% all bond 3 resin + 50% ethanol) was used, followed by the adhesive(ALL-BOND 3 RESIN) application. Resin composite build-ups were then prepared using an incremental technique. Specimens were sectioned into beams and submitted to a tensile load using a Micro Tensile Tester(Bisco Inc.). The data were statistically analyzed using one-way ANOVA and Tukey HSD at p<0.5 level. There was no significant difference on G1(control) and G2(irrigated with NaOCl only ). (p>0.05). G3(flushed with EDTA) showed significantly high tensile bonding strength compared to the G2 (p<0.05). G4( treated with EDTA but no acid-etching) was significantly lower value than G3. (p<0.05) Although there was no significant difference, 5.25% NaOCl seemed to have an adverse effect on the bonding strength of ethanol wet bonding. The flushing with EDTA after NaOCl irrigation prevents the decrease of bonding strength. The use of 17% EDTA as a final flush can enhance the bonding strength but EDTA flushing can't substitute for a acid-etching.

Taxonomical Classification and Genesis of Cheongpung Series Distributed on Diluvial Terrace (홍적대지 토양인 청풍통의 분류 및 생성)

  • Song, Kwan-Cheol;Hyun, Byung-Geun;Sonn, Yeon-Kyu;Zhang, Yong-Seon;Park, Chan-Won;Jang, Byoung-Choon
    • Korean Journal of Soil Science and Fertilizer
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    • v.43 no.2
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    • pp.224-229
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    • 2010
  • This study was conducted to reclassify Cheongpung series based on the second edition of Soil Taxonomy, and to dicuss the formation of Cheongpung series distributed on the diluvial terrace. Morphological properties of typifying pedon of Cheongpung series were investigated, and physico-chemical properties were analyzed according to Soil survey laboratory methods manual. The typifying pedon of Cheongpung series has red (2.5YR 4/6) silty clay loam Ap horizon (0-18 cm), red (2.5YR 4/8) clay BAt horizon (18-35 cm), red (2.5YR 4/2) cobbly clay Bt1 horizon (35-65 cm), and red (2.5YR4/6) cobbly clay Bt2 horizon (more than 65 cm). The typifying pedon has an argillic horizon from adepth of 18 to more than 65 cm, and a base saturation (sum of cations) of less than 35% at 125 cm below the upper boundary of the argillic horizon. It can be classified as Ultisol, not as Alfisol. It has udic soil moisture regime, and can be classified as Udult. Also that meets the requirements of Typic Hapludults. It has 35% or more clay at the particle-size control section, and have mesic soil temperature regime. Therefore Cheongpung series can be classified as fine, mesic family of Typic Hapludults, not as fine, mesic family of Ultic Hapludalfs. Cheongpung series occur on moderately elevated diluvial terrace which have relatively stable geomorphic surface. They are developed as Ultisols with clay mineral weathering, translocation of clays to accumulate in an argillic horizon, and leaching of base-forming cations from the profile for relatively long periods under humid, and temperate climates in Korea.

The Hydrochemical and Stable Isotope Characteristics of Shallow Groundwater Near the Gwangju Stream (광주천 인근 천부 지하수의 수리화학 및 안정동위원소 특성)

  • Yoon, Wook;Ji, Se-Jung;So, Chil-Sub
    • Economic and Environmental Geology
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    • v.36 no.6
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    • pp.441-455
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    • 2003
  • The most common water types are found to be Ca-HCO3, Ca-Na-HCO3 and Ca-Na-HCO3-Cl in Gwangju groundwater. Groundwater near the Gwangju stream are characterized Ca-Cl water type, with over 50 mg/L of C1- and 400 μS/cm of EC. The systematic variation of Cl, HCO3,- EC and γ18O values in groundwater with distance away from drainages is caused by streamwater infiltration. Stable isotope data indicate that γD and γ18O values of groundwaters near drainages were enriched by evaporation effect, showing a equation of γD=7. 1×γ18O-1. γ18O values over -6\textperthansand are anomalous in the unconfined groundwater zones, which are influenced by the local surface water enriched in 18O composition. Groundwater in highland shows remarkably light γ18O values below -8\textperthousand. The infiltration of streamwater is dominant in unconfined alluvium aquifer near drainages. γ13CDIC values (-17.6∼-15.2\textperthousand) of groundwaters near drainages revealed that dissolved inorganic carbon (DIC) is predominantly originated from natural soil-derived CO2. γ15N and γ18O values of nitrate are 0∼17.0\textperthansand and 6.6∼17.4\textperthansand, respectively. Relationship between γ15N and γ18O shows a systematic isotopic fractionation caused by denitrification of 40∼60%, suggesting that the major source of groundwater nitrate originated from nitrate of soils, and mixing nitrate of soil and sewage or manure.

Studies on Processing ana Keeping Quality of Retort Pouched Foods (3) Preparation and Keeping Quality of Retort Pouched Fried Mackerel Meat Paste (레토르트파우치식품의 가공 및 품질안정성에 관한 연구 (3) 레토르트파우치 튀김어묵의 제조 및 저장중의 품질안정성)

  • LEE Eung-Ho;OH Kwang-Soo;KOO Jae-Geun;PARK Hyang-Suk;CHO Soon-Yeong;CHA Yong-Jun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.17 no.5
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    • pp.373-382
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    • 1984
  • Processing conditions of retort pouched fried mackerel fish meat paste and quality stability during storage were investigated. The reasonable amounts of added ingredients to the frozen mackerel meat paste were 10% of corn starch, 1% of soybean protein, 1.5% of sodium chloride, 0.6% of monosodium glutamate, 0.3% of alcoholic extract of red pepper, and 0.1% of sodium erythorbate as an antioxidant and also added water corresponding to 10% of the frozen mackerel meat paste. After grinding the defrosted mackerel fish meat paste with ingredients, the meat paste was molded in bar type and fried in soybean oil at 170180C for 3 minutes. The fried mackerel meat paste was cooled, vacuum-packed in laminated plastic film bag (polyester/polyvinylidene chloride/unoriented polypropylene : 12μm/15μ/50μm,14×19cm) and finally sterilized at 120C for 20 minutes in a hot water circulating retort. The pH, volatile basic nitrogen, moisture content, water activity, color, thiobarbituric acid value, peroxide value, texture and viable bacterial count of products were examined during 100 days of storage at 25±3Cand5C. The results showed that products could be preserved in good condition for 100 days at 25±3C. Judging from sensory evaluation, the quality of products was not inferior to that of market products.

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THE EFFECT OF THERMOCYCLING ON THE DURABILITY OF DENTIN ADHESIVE SYSTEMS (열순환이 상아질 접착제의 결합 내구성에 미치는 영향)

  • Moon, Young-Hoon;Kim, Jong-Ryul;Choi, Kyung-Kyu;Park, Sang-Jin
    • Restorative Dentistry and Endodontics
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    • v.32 no.3
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    • pp.222-235
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    • 2007
  • The objectives of this study was to evaluate the effect of thermocycling on the μTBS (microtensile bond strength) to dentin with four different adhesive systems to examine the bonding durability. Freshly extracted 3rd molar teeth were exposed occlusal dentin surfaces, and randomly distributed into 8 adhesive groups 3-steps total-etching (Scotchbond Multi-Purpose Plus; SM, All Bond-2; AB), 2-steps total-etching (Single Bond; SB, One Step plus; OS), 2-steps self-etching (Clearfil SE Bond; SE, AdheSE AD) and single-step self-etching systems (Promp L-Pop; PL, Xeno III; XE) Each adhesive system in 8 adhesives groups was applied on prepared dentin surface as an instruction and resin composite (Z250) was placed incrementally and light-cured. The bonded specimens were sectioned with low-speed diamond saw to obtain 1×1mm sticks after 24 hours of storage at 37C distilled water and proceeded thermocycling at the pre-determined cycles of 0, 1,000 and 2,000. The μTBS test was carried out with EZ-tester at 1mm/min. The results of bond strength test were statistically analyzed using one-way ANOVA/ Duncan's test at the a < 0.05 confidence level. Also, the fracture mode of debonded surface and the interface were examined under SEM. The results of this study were as follows ; 1. 3-step total etching adhesives showed stable, but bond strength of 2-step adhesives were decreased as thermocycling stress. 2. SE showed the highest bond strength, but single step adhesives (PL, XE) had the lowest value both before and after thermocycling. 3 Most of adhesives showed adhesive failure. The total-etching systems were prone to adhesive failure and the single-step systems were mixed failure after thermocycling. Within limited results of this study, the bond strength of adhesive system was material specific and the bonding durability was affected by the bonding step/ procedure of adhesive Simplified bonding procedures do not necessarily imply improved bonding performance.

A study of the antifungal properties and flexural strength of 3D printed denture base resin containing titanium dioxide nanoparticles (이산화티타늄 나노입자를 함유한 3D 프린팅 의치상 레진의 항진균성 및 굽힘 강도에 대한 연구)

  • Seok-Won Yoon;Young-Eun Cho
    • The Journal of Korean Academy of Prosthodontics
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    • v.62 no.2
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    • pp.95-103
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    • 2024
  • Purpose. With the advancement of digital technology, 3D printing is being utilized in the fabrication of denture base. Nevertheless, increasing microbial adhesion to the surface of denture base has been reported as the disadvantage of 3D-printed denture base. The purpose of this study is to investigate the antifungal properties and flexural strength of 3D-printed denture base resin according to the different contents of titanium dioxide nanoparticles. Materials and methods. Titanium dioxide nanoparticles were mixed with the 3D printing resin at the ratios of 0.5, 1, 1.5, and 2 wt%. Twenty specimens per each group were printed in the form of cylindrical shape (diameter: 20 mm, height: 3 mm) to evaluate antifungal properties. Ten specimens from each group underwent polishing using autogrinder, while the remaining ten specimens did not. Candida albicans in hyphae form was inoculated onto each specimen, optical density and colony-forming unit were analyzed. The surface of the specimen was observed using scanning electron microscopy. To evaluate the flexural strength, twenty specimens per each group were 3D printed in the form of rectangular prism shape (length: 64 mm, height: 10 mm, width: 3 mm) and three-point bending tests were conducted using universal testing machine according to ISO 20795-1. Results. Colony-forming unit of C.albicans and optical density of culture medium showed no difference between non-polished groups, but decreased in the polished groups at concentration of 1, 1.5, 2 wt% titanium dioxide nanoparticles. Flexural strength increased with titanium dioxide nanoparticle at concentration of 0.5, 1, 1.5 wt%, but decreased at 2 wt% compared to 1.5 wt%. Conclusion. When 1.5 wt% of titanium dioxide nanoparticles were added to the 3D-printed denture base resin with polishing, antifungal properties were increased.

Formation Environment of Quaternary deposits and Palynology of Jangheung-ri Archaeological Site (Jiphyeon County, Jinju City), Korea (진주 집현 장흥리 유적 제4기 퇴적층 형성 및 식생환경 연구)

  • 김주용;박영철;양동윤;봉필윤;서영남;이윤수;김진관
    • The Korean Journal of Quaternary Research
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    • v.16 no.2
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    • pp.9-21
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    • 2002
  • In Korea, many open-air upper palaeolithic sites are located at the river valley, particularly exposed in gently rotting terrain along the river course. They are situated at an altitude less trail 30 m above present river bottom, and covered with the blankets of slope deposits of several meters in thickness. The purpose of this research is to eluridate depositional and vegetational environment of the alluvial upper palaeolithic Jangheung-ri sites on the basis of analytical properties of grain size population, chronology, palynology, soil chemistry and clay mineralogy and magnetic susceptibility of the Jangheung-ri Quaternary formations. The lithostratograpy of Jangheung-ri sit is subdivided into 3 layers based on the depositional sequence and radiocarbon ages. From bottom to top, they are composed of slope deposits with lower paleosol layers, young fluvial sand and gravel with backswamp organic muds, and upper paleosol layers. The upper paleosol was formed under rather dry climatic condition between each flooding period. Dessication cracks were prevalent in the soil solum which was filled with secondarily minuted fragments due to pedogenetic process. The soil structure shows typical braided-typed cracks in the root part of cracking texture, and more diversified pattern of crackings downward. The young fluvial sand gravel were formed by rather perennial streams after LGM. The main part of organic muds was particularly formed after 15Ka. Local backswamp were flourished with organic muds and graded suspension materials in the flooding muds were intermittently accumulated in the organic muds until ca. 11Ka. This episode was associated with migration of Nam River toward present course. Organic muds were formed in backswamp or local pond. Abies/Picea-Betula with Ranunculaceae, Compositae, Cyperaceae were prevalent. This period is characterized with BΦlling, Older Dryas, Allerod, and Younger Dryas (MIS-1). Stone artefacts were found in the lower paleosol layers formed as old as 18Ka-22Ka. Based on the artefacts and landscape settings of the Jangheung-ri site, it is presumed that settlement grounds of old people were buried by frequent floodings of old Nam River, the river-beds of which were heavily fluctuated laterally and river-bed erosions were activated from south to north in Jangheung-ri site until the terminal of LGM9ca 17Ka).

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Precessing of Smoked Dried and Powdered, Sardine for Instant Soup (정어리 분말수우프의 가공)

  • Oh, Kwang-Soo;Chung, Bu-Kil;Kim, Myung-Chan;Sung, Nak-Ju;Lee, Eung-Ho
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.17 no.2
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    • pp.149-157
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    • 1988
  • This study was carried out to prepare the flavoring substance using sardine for instant soup, and to examine the taste compounds and storage stability of the product. In preparation of product, raw sardine are gutted, boiled for 10 minutes and smoked 3 times to 910 moisture content at 80C for 8 hours. The smoked-dried sardine meat were followed to be 50 mesh of particle size. The powdered-dried sardine were mixed 4.0% sugar, 20.0% table salt, 3.0% monosodium glutamate, 0.2% black pepper, 0.2% garlic powder and 0.2% onion powder, Finally the powdered instant soup product were vacuum packed in a laminated film(PET/A1 foil/CPP) bag, and then stored at room temperature for 120 days. The effect of smoking on enhancing flavor and on preventing lipid oxidation of product during storage were observed. From the chemical analysis and omission test, the principal taste compounds of product were IMP, 478.2mg/l00g; free amino acids such as glutamic acid, histidine, arginine, phenylalaine 3292.5mg/l00g; non-volatile organic acids such as lactic acid, αketoglutaric acid, 712.2mg/l00g; total creatinine 409.0mg/100g, and small amount of betaine, TMAO. Fatty acid composition of product were mainly consisted of polyenoic acids such as 20:5, 22:6, followed by saturated acids, monoenoic acid. The major fatty acid were 16:0, 16:1, 18:1, 20:5 and 22:6. From the results of sensory evaluation and chemical experiments during storage, the vacuum packed product were good condition for preserving the quality during storage for 120 days. We may conclude that the quality of present product was not inferior to that of seasoning powder of anchovy on the market, and it can be commercialized as a flavoring substance in preparing soup and broth.

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