• Title/Summary/Keyword: Physical and chemical properties

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잎담배 건조중 산소공급에 따른 내용성분 및 물리성 변화 (Effect of Oxygen Supply on Chemical Composition and Physical Properties of Tobacco Leaves During Flue-curing)

  • 황건중;석영선
    • 한국연초학회지
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    • 제18권1호
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    • pp.49-53
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    • 1996
  • This experiment was carried out to study the effect of oxygen on chemical composition and physical properties of tobacco leaves during flue-curing. The results obtained were as follows: Starch content decreased and sucrose content increased with increasing oxygen supply during curing. Glucose and fructose of the cured leaves showed high content at the 5-10% oxygen supply. Amino-N and nitrate-N increased with increasing oxygen supply. Total nitrogen and NH4-N showed the lowest value at the 5-10% and 10-15% oxygen supply in the cutters and leaf, respectively. Chlorophyll and chlorogenic acid increased, and total volatile base decreased with increasing oxygen supply. The activity of α-amylase increased at the latter period of flue-curing, and the maximum activity point were delayed 12 hours with increasing oxygen supply. Shatter index of cured leaves decreased with increasing oxygen supply. It was desirable to supply oxygen during flue-curing for the improvement of chemical and physical properties such as starch, total sugar, chlorogenic acid, and shatter index of cured leaves.

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석탄 유분에 대한 물성예측식 개발 및 공정에 대한 연구 (Thermodynamic Correlations for Predicting the Properties of Coal-Tar Fractions and Process Analysys)

  • 오준성;이의수;박상진
    • Korean Chemical Engineering Research
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    • 제43권4호
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    • pp.458-466
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    • 2005
  • 회분식 증류 공정을 모델링하기 위해서는 평형상수와 엔탈피값이 필요하며 이 값들은 열역학적인 계산 방법에 의해 계산된다. 석탄 유분인 coal tar의 경우에는 성분이 다양하고 coal tar내의 성분을 대부분 알 수 없으므로 가상성분으로 만들어 적절한 물성예측식을 사용하여 물성값을 계산해 주어야 한다. 본 연구에서는 기존의 물성예측식에 의해 계산된 값과 이미 알려진 coal tar 유분의 실제물성값의 차이를 기 개발된 물성예측식에 대해 비교하였고 물성예측식에 필요한 2개의 parameter(NBP, SG)대신 1개의 변수(NBP)를 사용하여 간단한 물성예측식을 도출하였다. 또한 이상 기체 열용량 예측식의 경우에도 같은 방법을 적용하였다. 개발된 물성 예측식 및 회분식 증류공정프로그램은 coal tar계에 적용하여 coal tar 중 유효성분 분리를 위해 효율적으로 적용할 수 있다 하겠다.

The Calculation of Physical Properties of Amino Acids Using Molecular Modeling Techniques (II)

  • Lee, Myung-Jae;Kim, Ui-Rak
    • Bulletin of the Korean Chemical Society
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    • 제25권7호
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    • pp.1046-1050
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    • 2004
  • Six physical properties (enthalpy, density, decomposition temperature, solubility in water, pKa values, and hydronium potential) were examined by molecular modeling techniques. The molecular connectivity index, Wiener distance index, and Ad hoc descriptor are employed as structural parameters to encode information about branching, size, cyclization, unsaturation, heteroatom content, and polarizability. This paper examines the correlation of the molecular modeling techniques parameters and the physicochemical properties of amino acids. As a results, calculated values were in agreement with experimental data in the above six physical properties of amino acids and the molecular connectivity index was superior to the other indices in fitting the calculated data.

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

  • 백상현;이종열;엄태선;임채용;안광원
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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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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Effect of Surfactant on the Physical Properties and Crosslink Density of Silica Filled ESBR Compounds and Carbon Black Filled Compounds

  • Hwang, Kiwon;Kim, Woong;Ahn, Byungkyu;Mun, Hyunsung;Yu, Eunho;Kim, Donghyuk;Ryu, Gyeongchan;Kim, Wonho
    • Elastomers and Composites
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    • 제53권2호
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    • pp.39-47
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    • 2018
  • Styrene-butadiene rubber (SBR) is widely used in tire treads due to its excellent abrasion resistance, braking performance, and reasonable cost. Depending on the polymerization method, SBR is classified into solution-polymerized SBR (SSBR) and emulsion-polymerized SBR (ESBR). ESBR is less expensive and environmentally friendlier than SSBR because it uses water as a solvent. A higher molecular weight is also easier to obtain in ESBR, which has advantages in mechanical properties and tire performance. In ESBR polymerization, a surfactant is added to create an emulsion system with a hydrophobic monomer in the water phase. However, some amount of surfactant remains in the ESBR during coagulation, making the polymer chains in micelles clump together. As a result, it is well-known that residual surfactant adversely affects the physical properties of silica-filled ESBR compounds. However, researches about the effect of residual surfactant on the physical properties of ESBR are lacking. Therefore, in this study we compared the effects of remaining surfactant in ESBR on the mechanical properties of silica-filled and carbon black-filled compounds. The crosslinking density and filler-rubber interaction are also analyzed by using the Flory-Rehner theory and Kraus equation. In addition, the effects of surfactant on the mechanical properties and crosslinking density are compared with the effects of TDAE oil (a conventional processing aid).

POSS/Polyurethane Hybrids and Nanocomposites: A Review on Preparation, Structure and Performance

  • Diao, Shuo;Mao, Lixin;Zhang, Liqun;Wang, Yiqing
    • Elastomers and Composites
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    • 제50권1호
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    • pp.35-48
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    • 2015
  • Polyhedral oligomeric silsesquioxane (POSS) is an important inorganic-organic hybrid material with a three-dimensional structure. Polyurethane (PU) is a widely applied polymer that has versatile properties with the change of two phase structure. When POSS is incorporated into PU by physical or chemical methods, many properties can be greatly improved, such as mechanical properties, thermal stability, biodegradation resistance, and water resistance. This paper reviews the recent progress in preparation, structure, and performance of POSS-modified polyurethane from the viewpoint of physical blending and chemical modification.

수작업 박피밤과 화염박피 밤의 물리화학적 특성 (The Physicochemical Properties of Hand-Peeled and Flame-Peeled Chestnuts)

  • 김종훈;박재복;최창현
    • Journal of Biosystems Engineering
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    • 제24권5호
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    • pp.407-414
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    • 1999
  • To evaluate the quality of flame-peeled chestnuts, their physical and chemical properties were analyzed. The physicochemical properties of flame-peeled chestnuts, including geometrical shape, texture and chemical composition, were compared to those of hand-peeled ones. For the flame-peeled chestnuts, some properties in heated and non-heated sections were separately analyzed. The color, texture such as springness, cohesiveness, adhesiveness, hardness and chewiness, moisture content, and reducing sugar of the heated section of the flame-peeled chestnuts were significantly different with their non-heated section. But the physicochemical properties of the non-heated section of the flame-peeled chestnuts were similar to those of the hand-peeled ones.

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Hydrogeological Characteristics of a Riverine Wetland in the Nakdong River Delta, Korea

  • Jeon, Hang-Tak;Cha, Eun-Ji;Lim, Woo-Ri;Yoon, Sul-Min;Hamm, Se-Yeong
    • 한국지구과학회지
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    • 제42권4호
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    • pp.425-444
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    • 2021
  • Investigating the physical and chemical properties of riverine wetlands is necessary to understand their distribution characteristics and depositional environment. This study investigated the physical (particle size, color, and type) and chemical properties (organic, inorganic, and moisture contents) of sediments in Samrak wetland, located in the Nakdong River estuary area in Busan, South Korea. The particle size analysis indicated that the hydraulic conductivity values for the coarse grain and the mixture of coarse and fine grains ranged from 2.03 to 3.49×10-1 cm s-1 and 7.18×10-3 to 1.24×10-7 cm s-1, respectively. In-situ water quality and laboratory-based chemical analyses and radon-222 measurement were performed on groundwater and surface water in the wetland and water from the nearby Nakdong River. The physical and chemical properties of Samrak wetland was characterized by the sediments in the vertical and lateral direction. The concentrations of chemical components in the wetland groundwater were distinctly higher than those in the Nakdong River water though the wetland groundwater and Nakdong River water equally belonged to the Ca-HCO3 type.

버어리종 건조방법이 건엽의 품질에 미치는 영향 (Effects of Curing Methods on the Quality of Cured Leaves in Burley Tobacco (N. tabacum L.))

  • 배성국;조천준;임해건;김요태
    • 한국연초학회지
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    • 제20권1호
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    • pp.26-32
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    • 1998
  • This study was conducted to obtain the basic information on the burley tobacco (Nicotiana tabacum L.) curing methods. The effects of the three kinds of curing methods on the dry weight losses during curing, chemical contents and physical properties of cured leaves, and organoleptic and smoking qualities were observed. The dry weight losses during curing was the highest in the stalk curing, and the lowest in the conventional priming. The longer the curing periods was, the more the loss of dry weight. The percent of the excessive dried leaves was high and the price per kilogram was low in the conventional priming. The chemical contents and the physical properties of the cured leaves in the conventional priming were similar to those of yellowing or browning stage of curing. But, the chemical contents and the physical properties of the cured leaves in the stalk curing were comparable to those of the air curing. The smoking quality was the best in the stalk curing.

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Polished Wafer와 Epi-Layer Wafer의 표면 처리에 따른 표면 화학적/물리적 특성 (Comparison on the Physical & Chemical Characteristics in Surface of Polished Wafer and Epi-Layer Wafer)

  • 김진서;서형탁
    • 한국재료학회지
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    • 제24권12호
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    • pp.682-688
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    • 2014
  • Physical and chemical changes in a polished wafer and in $2.5{\mu}m$ & $4{\mu}m$ epitaxially grown Si layer wafers (Epilayer wafer) after surface treatment were investigated. We characterized the influence of surface treatment on wafer properties such as surface roughness and the chemical composition and bonds. After each surface treatment, the physical change of the wafer surface was evaluated by atomic force microscopy to confirm the surface morphology and roughness. In addition, chemical changes in the wafer surface were studied by X-ray photoemission spectroscopy measurement. Changes in the chemical composition were confirmed before and after the surface treatment. By combined analysis of the physical and chemical changes, we found that diluted hydrofluoric acid treatment is more effective than buffered oxide etching for $SiO_2$ removal in both polished and Epi-Layer wafers; however, the etch rate and the surface roughness in the given treatment are different among the polished $2.5{\mu}m$ and $4{\mu}m$ Epi-layer wafers in spite of the identical bulk structural properties of these wafers. This study therefore suggests that independent surface treatment optimization is required for each wafer type, $2.5{\mu}m$ and $4{\mu}m$, due to the meaningful differences in the initial surface chemical and physical properties.