• Title/Summary/Keyword: physical and chemical effects

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Preliminary Studies on Double-Diffusive Natural Convection During Physical Vapor Transport Crystal Growth of Hg2Br2 for the Spaceflight Experiments

  • Ha, Sung Ho;Kim, Geug Tae
    • Korean Chemical Engineering Research
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    • v.57 no.2
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    • pp.289-300
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    • 2019
  • We have conducted a preliminary numerical analysis to understand the effects of double-diffusive convection on the molar flux at the crystal region during the growth of mercurous bromide ($Hg_2Br_2$) crystals in 1 g and microgravity (${\mu}g$) conditions. It was found that the total molar fluxes decay first-order exponentially with the aspect ratio (AR, transport length-to-width), $1{\leq}AR{\leq}10$. With increasing the aspect ratio of the horizontal enclosure from AR = 1 up to Ar = 10, the convection flow field shifts to the advective-diffusion mode and the flow structures become stable. Therefore, altering the aspect ratio of the enclosure allows one to control the effect of the double diffusive natural convection. Moreover, microgravity environments less than $10^{-2}g$ make the effect of double-diffusive natural convection much reduced so that the convection mode could be switched over the advective-diffusion mode.

STUDIES ON THE CHLORINE OF BURLEY TOBACCO PLANTS II. THE EFFECTS OF CHLORINE ON THE YIELD CHEMICAL CONSTITUENTS AND PHYSICAL PROPERTIES OF LEAF TOBACCO. (버어리종 담배의 염소에 관한 연구 II. 염소시용이 잎담배의 수량 및 이화학성에 미치는 영향)

  • 김상범;배길관
    • Journal of the Korean Society of Tobacco Science
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    • v.8 no.1
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    • pp.57-67
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    • 1986
  • This study was conducted to find out the effects of chlorine on the yield, chemical constituents and physical properties of Burley leaf tobacco. The results obtained are as follows. 1. There was no significant differences in growth and yield among chlorine application levels. 2. When chlorine being applied 4kg/10a or more, the cured leaf showed higher chlorine content and lower leaf quality remarkably. It was estimated that the critical application of chlorine was 3kg/10a. 3. Total nitrogen and alkaloid contents of cured leaf were increased by chlorine application, while the phosphorus, calcium and magnesium were not affected. 4. The reflectance color of red and yellow were decreased by cvhlorine application in cured leaf of field grown tobacco.

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Physical and chemical Cross-Linking Effects in Thermoplastic Polyurethane Elastomers with Different Macroglycol

  • Heo, Jae-Ho;Jeong, Du-Gam;Kim, Eun-Young;Kim, Han-Do
    • Proceedings of the Korean Fiber Society Conference
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    • 1997.10a
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    • pp.126-130
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    • 1997
  • A series of Thermoplastic polyurethane elastomers was prepared via a two-step polymerization process. The NCO/OH feed ratio of polyurethane synthesized in this study was varied from 1 to 1.3. Studies have been made on the effects of chemical and physical cross-linkina, and the properties of thermoplastic polyurethane elastomers based on isophorone diisocyanate (IPDI)/1,4-butanediol (BD)/poly(propylene glycol) (PPG, MW:2000), isophorone diisocyanate (IPDI)/BD /poly(oxytetramethylene) glycol (PTMG, MW:2000) was compared. These materials were characterized using FTIR spectrometer, dynamic mechanical thermal analyzer, and tensile retraction tester. PTMG based polyurethane elastomers showed higher elasomeric behavior than PPG based polyurethane elastomers at the same NCO/OH ratio. This feature has been connected with the specific nature of the polyols. The permanent set(%) was decreased with increasing maximum elongation from 50% to 300%.

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Parmeter Optimization for Calculation of Proton Chemical Shift in Protein

  • Park, Kyunglae;Wil
    • Journal of the Korean Magnetic Resonance Society
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    • v.1 no.2
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    • pp.71-78
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    • 1997
  • The magnetic anisotropy effects of peptide group in structured protein on proton chemical shift have been investigated using trialanine modeling. The structure dependent part of chemical shift of C${\alpha}$H of the second amino acid residue was assumed to come purely from the magnetic anisotropy effects of C=O and C-N bonds of peptide in the direct neighborhood and thus to be dependent on and $\psi$ angle of this dipeptide. A set of dipeptide models with different and $\psi$angles were generated and from these models the chemical shift values were calculated using known algorithm to emphasize the role of parameters used in the equation. Comparison of sets of different parameters resulted in an optimized parameters which could reproduce the statistical chemical shift values observed in proteins with respect ot the secondary conformation.

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Effects of Propylene Glycol on the Physical Properties of Poly(vinyl alcohol) Solutions and Films

  • Cho, Yong-Han;Kim, Byoung-Chul;Dan, Kyung-Sik
    • Macromolecular Research
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    • v.17 no.8
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    • pp.591-596
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    • 2009
  • To trace the plasticizing effects of propylene glycol (PG) on poly(vinyl alcohol) (PVA), the rheological properties of PVA solutions in dimethyl sulfoxide (DMSO) and the physical properties of PVA films were discussed in terms of PG content. Both properties were closely related to the hydrogen bond breaking effects of PG The 6 and 12 wt% PVA solutions containing PG exhibited Bingham behavior, which was more noticeable at lower plasticizer content and higher polymer concentration. The 6 wt% PVA solutions containing more than 30 wt% PG showed a sudden decrease of viscosity over the frequency range of 0.08 and 0.2 rad/s. However, the 12 wt% PYA solutions showed no viscosity reduction even at a PG content up to 40 wt%. The glass transition temperature of the PVA/PG films was almost linearly decreased with increasing PG content but an abrupt reduction was observed at a plasticizer content 30 wt%, suggesting that the hydrogen bond breaking effects of PG on PVA became dominant between 20 and 30 wt%. This effect was further supported by the similar tendency of the tensile properties.

Influence of Blending Method on the Generation of Wear Particulate Matters and Physical Properties in TBR Tire Tread Compounds

  • Sanghoon Song;Junhwan Jeong;Jin Uk Ha;Daedong Park;Gyeongchan Ryu;Donghyuk Kim;Kiwon Hwang;Sungwook Chung;Wonho Kim
    • Elastomers and Composites
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    • v.58 no.4
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    • pp.161-172
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    • 2023
  • Because particulate matter has emerged as a major contributor to air pollution, the tire industry has conducted studies to reduce particulate matters from tires by improving tire performance. In this study, we compared the conventional blending method, in which rubber, filler, and additives are mixed simultaneously, to the Y-blending method, in which masterbatches are blended. We manufactured carbon black (CB)-filled natural rubber (NR)/butadiene rubber (BR) blend and silica-filled epoxidized NR/BR blend compounds to compare the effects of the two blending methods on the physical properties of the compounds and the amount of particulate matter generated. The Y-blending method provided uniform filler distribution in the heterogeneous rubber matrix, improved processability, and exhibited low rolling resistance. This method also improved physical properties owing to the excellent filler-rubber interaction. The results obtained from measuring the generation of particulate matter indicated that, the Y-blending method reduced PM2.5 particulate matter generation from the CB-filled and silica-filled compounds by 38% and 60%, and that of PM10 by 29% and 67%, respectively. This confirmed the excellence of the Y-blending method regarding the physical properties of truck bus radial tire tread compounds and reduced particulate matter generated.

Improvement of Physical Characteristics of Paper with Micro Pulp (마이크로 펄프를 이용한 종이의 물성 개선)

  • Kim, Hak-Sang;Kim, Bong-Yong
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.40 no.1
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    • pp.9-14
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    • 2008
  • Beating and using chemical agents are common methods to improve physical properties. But the beating is high energy consumption process and chemical agent addition may cause deteriorate waste water quality. Therefore, it is necessary to use more environment-friendly methods. In this study, micro pulp was used in the handsheet making to get improving effects of physical properties without beating treatment and chemicals. Stiffness, thickness and air permeability were increased and strength properties of paper were also improved to some extents by only the micro pulp addition.

The Trend of Foreign Sunscreen Products and Study of UV Protecting Effects (외국 자외선제품의 동향과 UV차단 효과 연구)

  • 우건희
    • Proceedings of the SCSK Conference
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    • 1992.09a
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    • pp.97-114
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    • 1992
  • In these days sun products are developed and produced by the cosmetic scientists in the world. Peoples need strongly to protect themselves from the hazardous UV rays dued to the destruction of ozone layer. Therfore, we, cosmetic scientists must have an effort to produce the more effective goods. In this article the market survey of sun-products as well as the currency of sunscreen agents was investigated. It was found that Benzophenone - 3 and Ocytyl methoxy cinnamate were widely used. The lotions, using Benzophenone - 3 as the chemical agents, and TiO$_2$and micro TiO$_2$ as the physical agents, were measured the UV-Spectrum in the Dilution and Application method. Photoprotective activity of chemical agents can usually be measured in solution state. However, that of the insoluble physical agents such as TiO$_2$is hardly measured in this state. Photoprotective ability of the insoluble physical agents was able to be measured by application of lotions to the surface of UV cells. It was found by this method that micro TiO$_2$showd stronger UV scattering effect than TiO$_2$in this method.

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Addition of Capsicum oleoresin, Carvacrol, Cinnamaldehyde and their mixtures to the broiler diet II: Effects on meat quality

  • Ipcak, Hasan Huseyin;Alcicek, Ahmet
    • Journal of Animal Science and Technology
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    • v.60 no.4
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    • pp.9.1-9.11
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    • 2018
  • Background: In recent years, with the prohibition of antibiotics used as growth stimulants in the nutrition of farm animals, researchers have searched for alternative natural and reliable products in order to be able to sustain the developments experienced during the use of antibiotics and to overcome the possible inconveniences. In this context, studies on evaluation of essential oils in poultry nutrition have been reported to improve the utilization of feed, stimulate the release of digestive enzymes, increase absorption in the stomach and intestines, antimicrobial and anti-parasitic effects and thus, can be an alternative to antibiotics and improve meat quality as well. Indeed, this study has been carried out to explore the effects of the addition of 150 mg/kg capsicum oleoresin (CAP), carvacrol (CAR), cinnamaldehyde (CIN) or their mixture (CAP+CAR+CIN) into the broilers' ration over sensory, physical and chemical properties in breast meat and leg meat. Methods: Experiments were conducted over 400 male and female broiler chicks (Ross-308) in 5 groups (1 control group and 4 treatment groups), each composed of 80 chicks. The control group was fed without feed additives while the second, third, fourth and the fifth groups were fed with 150 mg CAP/kg feed, 150 mg CAR/kg feed, 150 mg CIN/kg feed, and 150 mg CAP+CAR+CIN/kg feed, respectively. Results: Addition of CAP, CAR, CIN or CAP+CAR+CIN had effects on the sensory (of taste, tenderness, juiciness and overall acceptability); physical properties (of $L^*$ value and toughness), the chemical properties (of DM, CF, CP, linoleic, EPA, behenic, MUFA, PUFA and ${\Sigma}n-6$ of the leg meat), the physical characteristics (of toughness and firmness), and the chemical properties (of CF, CP, linoleic, ecosenic, EPA, lignoseric, MUFA and ${\Sigma}n-3$) of the breast meat in comparison to control group. Furthermore, while the treatments had positive impacts on thawing loss, cooking loss and water holding capacity in both breast and leg meat; no effect was observed on pH value and lipid oxidation on day 1, day 4 and day 8. Conclusion: The results strongly suggested that the addition of CAP, CAR, CIN or CAP+CAR+CIN to the rations of the broiler chicks changed the sensory, physical and chemical properties of breast and leg meat. It was also observed that these compounds were more effective when they were added to the ratio as a mixture rather than adding them individually.

The Effects of Various Cement Type and Compositions on the Material Properties of high Strength Concrete (시멘트 특성의 변화가 고강도콘크리트의 재료특성에 미치는 영향)

  • 백상현;이종열;엄태선;임채용;안광원
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.04a
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    • pp.47-52
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    • 2000
  • Recently, it is very necessary the development of the manufacturing techniques for high strength concrete(HSC) for the large-scale size and good quality of civil structure. But, the manufacture and quality control of HSC of which shrinkage, heat of hydration and workability at construction filed are considered, is very difficult due to its low water-cement ratio and high quantity of unit cement content. In the present study, we tried to know and assess the influences of chemical and physical properties of cement on the material properties of HSC. We analyzed basic properties of 4 kinds of cement whose chemical and physical properties are different each other through various tests such as chemical analysis and mortal test. Also, we performed the assessment of the material properties of HSC for each dement by the test for the conditions of same mix design and similar compressive strength. From the results in the study, the assessment of the important quality factors of cement influencing the properties of HSC may be utilized to quality control of applied cement to manufacture the HSC of high quality.

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