• Title/Summary/Keyword: Heat of cure

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COMPARISON OF MECHANICAL PROPERTIES IN 4 INDIRECT COMPOSITE RESIN (4종의 간접법용 복합 레진의 기계적 특성 비교)

  • Kim, Kil-Soo;Yoon, Tae-Ho;Song, Kwang-Yeob;Ahn, Seung-Geun
    • The Journal of Korean Academy of Prosthodontics
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    • v.45 no.1
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    • pp.21-33
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    • 2007
  • Statement of problem: The esthetic component of dental care has become increasingly more important, while new tooth-colored materials are continually marketed. Various new indirect composite materials have been developed with required advantages. The most recent development in the indirect composites has been the introduction of the second-generation laboratory composite or poly-glass materials. They are processed by different laboratory techniques based on combinations of heat, pressure, vacuum and light polymerization. Although, second generation products became available in 1995, their characteristics and clinical performance have not been adequately investigated. Purpose: The aim of this study was to measure the mechanical properties of the second generation indirect resin system and compare these with an existing universal direct composite resin. Material and method: In this study four indirect composite material (Adoro LC, BelleGlass HP, Tescera, Synfony) were tested for flexural strength, wear resistance, hardness and their degree of conversion against Z250, a light cure direct composite. Results: Within the limitations of this study, the following conclusions were drawn: 1. From the abrasion wear result, Adoro showed the least volume loss while Synfony showed the greatest volume loss. Z250 and BelleGlass HP didn't show significant difference (p>0.05), but they showed significant difference with other groups (p<0.05). From the attrition wear, BelleGlass HP showed the least volume loss and it didn’t show significant difference with Tescera (p>0.05). While Synfony showed the greatest volume loss that it showed significant difference with other groups (p>0.05). 2. Mean values of flexural strength by means of three point bending test was in the order of Z250, Adoro, Belleglass HP, Tescera and Synfony. Mean elastic modulus was in the order of Z250, BelleGlass HP, Tescera, Adoro and Synfony. 3. The result of Vicker‘s microhardness value showed that significantly higher value in Z250 (p<0.05), and is in the order of BelleGlass HP, Tescera, Adoro and Synfony. 4. The degree of conversion measured by FT-IR showed significantly higher value in BelleGlass HP (p<0.05), and is in the order of Adoro, Synfony, Tescera and Z250. Conclusion: Significant differences were found in the flexural strength, wear resistance, hardness and their degree of conversion.

A Study on the application of checking the exuberance of yang (潛陽) to treat apoplexy (중풍(中風)의 치법(治法) 중 잠양법(潛陽法)에 대한 문헌고찰)

  • Min, Gun-Woo;Park, Jong-Hyuck;Jung, Ji-Cheon
    • The Journal of Dong Guk Oriental Medicine
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    • v.9
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    • pp.127-138
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    • 2000
  • The methods of checking the exuberance of yang (潛陽法) are a kind of medical treatments which cure various symtoms caused by hyperactivity of liver-yang, at the same time used for treating apoplexy. Thus, I investigated the application of checking the exuberance of yang to treat stroke. The conclusions are as follows. We can find application of checking the exuberance of yang to apoplexy on Synopsis of the Gold Chamber. After Ye Gui who persisted the theory of endogenous wind, many physicians applied the method of checking the exuberance of yang and this method has usually applied with nourishing yin. The methods of checking the exuberance of yang are concretely applied as follows. 1) a portion of apoplexy involving the channels and collaterals, which is caused by deficiency of yin and wind-fire pathogen. 2) excessive-syndrome of coma accompanied by heat syndrome. 3) epilepsy caused old apoplexy. The majority of shells for example abalone shell, hawksbill shell, oyster shell, tortoise-shell etc. are the most frequent use of herbal drug which check the exuberance of yang. The precriptions of checking the exuberance of yang are Ho-jam-hwan(虎潛丸), Ko-bon-dan(固本丹), Cheon-ma-gu-deung-eum(天麻鉤藤飮), Chin-gan-sik-pung-tang(鎭肝熄風湯) etc.

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Studies on the Characteristics of Rubber Vulcanization Exotherm by Differential Scanning Calorimetry. (Differential Scanning Calorimetry에 의(依)한 고무의 가황발열특성(加黃發熱特性)에 관(關)한 연구(硏究))

  • Choi, Sei-Young;Paik, Nam-Chul
    • Elastomers and Composites
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    • v.19 no.1
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    • pp.13-31
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    • 1984
  • The purposes of this dissertation are to demonstrate that DSC theromoanaytical methods of vulcanization can provide useful informations on the vulcanization characteristics of industrial formulations and also provides the potential basis for a rapid and complete method of sulfur and vulcanizing accelerator analysis for quality control. The influences of those factors such as heating rate, scan temperature, vucanizing accelerator's type and concentration upon vulcanization exotherm in NR and NBR compounds in the presence of vulcanizing accelerators such as TMTD,MBTS,DPG,TMTM,CBS, and MBT were evaluated by means of DSC. In order to examine the credibility in the DSC method, the same samples which were used for DSC method were studied to compare the DSC results with the ODR (Oscillating Disk Rheometer) data. The results obtained were as follows 1. In the DSC dynamic experiments, the observed enthalpy results from vulcanization depends upon the heating rate; In the range of 2 to $20^{\circ}C/min$ of heating rate, as the heating rate was increased the enthalpy change was also increased. However, over the heating rate of $30^{\circ}C/min$ it was observed that the enthalpy change was decreased as the heating rate was further increased. Without regard to the change of enthalpy, tremendous instantaneous heat evolving was observed in the range of high heating rates. 2. For the samples which are added with various vulcanizing accelerators, the activation energies of vulcanization were as follows; 3. Regarding to the influences of vulcanizining accelerator's types upon the characteristics of vulcanization exotherm, NR and NBR compounds in the presence of thiuramsulphide compounds type accelerators such as TMTD, TMTM, were exhibited sharper and higher vulclanization exotherm than others. From the resuts of DSC thermograms which was distributed in even shape in the broad temperature range, it was clearly shown that the guanidine compounds type accelerator such as DPG acts as a delayed acting accelerator. 4. In the comparison of DSC and ODR results, the dependency of temperature in the cure rate and the observed conversions show good agreements between two results. 5. In the same curatives, by the comparison of glass transition temperatures, it was possible to predict relative values of maximum torques. Consequently, from the present studies, it is shown that the DSC thermoanalytical method can provide an alternate new method for rapid and complete quality control analysis of rubber industry.

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Anti-inflammatory effects of Herba Artemisiae Capillaris as a consequence of the inhibition of NF-kappa B-dependent iNOS and pro-inflammatory cytokines production. (Nuclear Factor kappa B 억제를 통한 인진추출물의 inducible Nitric Oxide synthase 및 Cytokine 억제효과)

  • Kim, Dae-Sung;Park, Sook-Jahr;Jo, Mi-Jeong;Park, Sang-Mi;Kim, Sang-Chan;Byun, Sung-Hui
    • Herbal Formula Science
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    • v.17 no.2
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    • pp.151-162
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    • 2009
  • Herba Artemisiae Capillaris is the dried bud of Artemisia capillaris Thunb, which has been used for expelling heat to loosen the bowels and normalizing gallbladder function to cure jaundice in traditional oriental medicines. In the present study, we evaluated the anti-inflammatory effects of the aqueous extracts of Herba Artemisiae Capillaris (HAC) in LPS-activated Raw 264.7 cells. Cells were treated with $1\;{\mu}g/ml$ of LPS 1 h before adding HAC extract. Cell viability was determined by MTT assay, and the relative level of NO was measured with Griess reagent. TNF-$\alpha$, IL-$1{\beta}$, and IL-6 cytokines were detected by ELISA. During the entire experimental period, all three doses of HAC extract (0.03, 0.10 and 0.30 mg/ml) had no significant cytotoxicity. LPS-activated cells showed increased NO levels and iNOS expressions compared to control. However, these increases were dramatically attenuated by treatment with HAC extract. Moreover, the inhibitory effects of HAC extract occurred in a dose-dependent manner. In addition, HAC extract reduced the translocation of $NF{\kappa}B$ into nuclear. HAC reduced production of IL-$1{\beta}$ and IL-6 by LPS, although it had no effects on TNF-$\alpha$. These results demonstrate that liquiritigenin exerts anti-inflammatory effects, which results from the inhibition of $NF{\kappa}B$ activation in macrophages, thereby decreasing production of iNOS and proinflammatory cytokines. Taken together, these results indicate that the aqueous extracts of Herba Artemisiae Capillaris warrant further development as an anti-inflammatory agent for the treatment of gram-negative bacterial infections.

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Antithrombin and Thrombosis Prevention Activity of Buckwheat Seed, Fagopyrum esculentum Moench (메밀 종자의 항트롬빈 활성과 혈전증 예방효과)

  • Sohn, Ho-Yong;Kwon, Chong-Suk;Son, Kun-Ho;Kwon, Gi-Seok;Ryu, Hee-Young;Kum, Eun-Joo
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.35 no.2
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    • pp.132-138
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    • 2006
  • Direct thrombin inhibitor, which is effective to prevent or cure the thrombosis, has been investigated in worldwide. In this study, we tried to screen antithrombosis agent from edible or medicinal plant. A strong antithrombin activity was identified from methanol or $95\%$ ethanol extract of buckwheat seeds. The solvent fractionation of buckwheat extracts using hexane, ethylacetate, butanol revealed that the butanol fraction has a prominent antithrombin activity. Thrombin time (blood-clot formation time) exceeded to over $2,000\%$ by addition of the butanol fraction at concentration of $312.5{\mu}g/mL$, whereas thrombin time extended to $336\%$ by addition of aspirin at concentration of $1,500{\mu}g/mL$. The butanol fraction showed anthrone-positive and ninhydrine-negative reaction. The active components were heat-liable, acid-unstable non-proteinous macromolecules (>30 KD). In vivo analysis using ICR male mouse showed that the buckwheat extract was superior than the aspirin in pulmonary thrombosis, KCN-induced coma and death. Our results suggest that the buckwheat is a potential as an antithrombosis agent and medicinal food.

Feasibility of Bladder Compression Molded Prepreg as Small Wind Turbine Blade Material (소형 풍력 터빈 블레이드 재료로서 블래더 가압 방식 몰드 성형 프리프레그의 타당성)

  • Yi, Bo-Gun;Seo, Seong-Won;Song, Myung-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.33 no.2
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    • pp.95-101
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    • 2020
  • The wind turbine blades should be designed to possess a high stiffness and should be fabricated with a light and high strength material because they serve under extreme combination of lift and drag forces, converting kinetic energy of wind into shaft work. The goal of this study is to understand the basic knowledge required to curtail the process time consumed during the construction of small wind turbine blades using carbon fiber reinforced polymer (CFRP) prepeg composites. The configuration of turbine rotor was determined using the QBlade freeware program. The fluid dynamics module simulated the loads exerted by the wind of a specific speed, and the stress analysis module predicted the distributions of equivalent von Mises stress for representing the blade structures. It was suggested to modify the shape of test specimen from ASTM D638 to decrease the variance in measured tensile strengths. Then, a series of experiments were performed to confirm that the bladder compression molded CFRP prepreg can provide sufficient strength to small wind turbine blades and decrease the cure time simultaneously.

Thermal Stability and Mechanical Interfacial Properties of DGEBA/PMR-15 Blend System Initiated by Cationic Latent Thermal Catalyst (잠재성 양이온 개시제를 이용한 DGEBA/PMR-15 블렌드계의 열안정성 및 기계적 계면 특성에 관한 연구)

  • Park, Soo-Jin;Lee, Hwa-Young;Han, Mijeong;Hong, Sung-Kwon
    • Journal of Adhesion and Interface
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    • v.5 no.1
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    • pp.3-11
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    • 2004
  • In this work, the cure behaviors of the DGEBA/PMR-15 blends initiated by N-benzylpyrazinium hexafluoroantimonate (BPH) as a cationic latent catalyst were performed in DSC and DMA analyses. And, the thermal stabilities were carried out by TGA analysis and their mechanical interfacial properties of blends were measured in the context of critical stress intensity factor ($K_{IC}$). As a result, the curing activation energy ($E_a$) determined from Ozawa's equation in DSC and the relaxation activation energy ($E_r$) from DMA were increased with increasing PMA-15 content. Also, the thermal stabilities obtained from the integral procedural decomposition temperature (IPDT) and the glass transition temperature ($T_g$) were highly improved with increasing the PMR-15 content, which were probably due to the high heat resistance. And, the $K_{IC}$ showed a similar behavior with $E_a$, which was attributed to the improving of the interfacial adhesion or hydrogen bondings between intermolecular chains.

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Treatment of Skin Diseases in Hyungsang Medicine (피부병의 형상의학적 치료)

  • Suk Min He;Hwang Won Duek;Jung Haeng Gyu;Lee Yong Tae
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.18 no.3
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    • pp.646-669
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    • 2004
  • By treating skin diseases with Hyungsang medicine and reviewing the clinical cases of them through classifying skin diseases into general care and into Hyungsang medical care, the writer came to the conclusion as followings. The skin is a house of Kyungnak, and it' s a place which Ki comes in and out, which human body controls conditions of his physiological function and which doctors can make a diagnosis from seeing it. The skin is subject to lung and large intestine in the point of organ, but in the point of movement, to spleen and stomach. Skin diseases come from unbalance of Ki and Hyul, mostly from fever in blood and also from Dam, Wind, Dampness and Dryness because of including fire. Generally skin diseases are treated according to classifying into distinctive symptoms, region, cause or time being occurred, and concomitant symptoms. After being divided into man and woman, age and youth, fatness and leanness, Jung Ki Shin Hyul type, visceral figures, Yukkyung shapes on Hyungsang medicine method, the remedy of skin diseases which is combined common meditation with Hyungsang medical method is efficacious. In distinguishing into man and woman, age and youth, man gets sick mainly by drinking liquor and exhausting Jung, woman is taken ill generally by indigestion and Damwha, especially by drinking liquor. Young child gets ill mostly from inherent weakness, but in many cases he is occurred by disturbed digestion, so he must be taken care of ingesting food. The aged becomes ill from weakening, so he must be treated according to reasons of diseases. To fatness and leanness, skin diseases are showed symptoms by weakened Yang, insufficient Yin or excess fever on the theory of upper and lower parts, by unbalance of Ki and Hyul on the theory of left and right, by Dryness and Dampness on the theory of front and rear and by insufficiency of vitality and combined fever on the theory of inside and outside. Therefore doctors must cure the symptoms according to the theory of upper and lower, left and right, front and rear and inside and outside. In type of Jung Ki Shin Hyul, the balances between Jung-Hyul and Shin-Ki are important points. Concretely Jung type comes to easily shortage of Jung or gathering abnormally Dampness and Dam, Ki type is easy to make a mass with Ki or to be deficient of Ki, Shin type comes to press seven emotions togather or to be insufficient of Yin and fever inside, and Hyul type is inclined to be deficient of Hyul and to become feverish or to be deficient of Ki. Therefore on the ground of the above reasons skin diseases come into existence. Inclusively in Jung-Hyul type , Ki must be moved on the base of full Jung-Hyul, so Wukmijiwhangtang or Samultang is prescribed basically. In Shin-Ki type , Jung-Hyul is saved on the base of moving Ki, so Hyangsosan or Yijintang is the proper prescription. Considering the visceral figures, doctors judge for diagnosis and remedy by putting together the elements, that is, great and small sizes of a set of features (eye, ear, mouth, nose), color and temper. The yukkyung types are classified according to many or few of Ki-Hyul, and then skin diseases appear by being inclined toward one side between Ki and hyul, or among the six atmospheric elements(wind, cold, heat, dampness, dryness, and fire). Especially because Yangmyung type is full of much Ki and Hyul, and also has much fever in stomach, he gets skin symptoms frequently. So his prescription is based on taking off fever in stomach, and also he must be careful about regimen certainly.

THERMAL CHANGE AND MICROHARDNESS IN CURING COMPOSITE RESIN ACCORDING TO VARIOUS CURING LIGHT SYSTEM (광중합기에 따른 복합레진 중합시 온도 변화와 미세경도에 관한 연구)

  • Lee, Dong-Jin;Kim, Dae-Eop;Yang, Yong-Sook;Lee, Kwang-Hee
    • Journal of the korean academy of Pediatric Dentistry
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    • v.31 no.3
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    • pp.391-399
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    • 2004
  • The purpose of this study was to compare curing efficiency of newly developed curing units to traditional halogen curing unit by measuring thermal change and surface microhardness according to curing light system. Materials and mathods : The types of curing units were traditional low intensity halogen light(Optilux 360), plasma arc light(Flipo), low heat plasma arc light(Aurys), low intensity LED(Starlight), and high intensity LED(Freelight2). Temperature at the tip of light guide was measured by a digital thermometer using K-type thermocouple. And after resin was filled to 2, 3, 4mm teflon mold, bottom temperature measured during curing. After 24 hours, microhardness of top surface and bottom surface of each resin specimen were measured. Results : The result of this study can be summarized as follows, 1. As measuring temperature of curing unit tips, Flipo is the highest as $52.4^{\circ}C,\;Freelight2(37.86^{\circ}C),\;Optilux360(32.68^{\circ}C),\;Aurys(32.34^{\circ}C),\;and\;Starlight(26.14^{\circ}C)$ were followed. 2. Flipo and Freelight2 were the highest similarly and Optilux360 and Aurys were similarly next and Starlight was lowest in temperature of bottom surface of resin mold. 3. Microhardness of top surface were generally similar, and Aurys was relatively low. 4. Optilux 360 and Freelight2 were the highest, and Flipo, Starlight, and Aurys were followed in microhardness of bottom surface. Conclusions : The results suggest that careful use of Flipo and Freelight2 might be able to cure greater depth of resin composite and do not cause thermal problems than other curing units.

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Inhibitory Substance on the Snake Venoms Produced by Penicillium sp. (사독의 조해물질에 관한 연구)

  • Seu, Jung-Hwn;Yi, Dong-Heui
    • Microbiology and Biotechnology Letters
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    • v.7 no.2
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    • pp.75-89
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    • 1979
  • One strain of Penicillium sp. (175-66-B), isolated from soil, was able to produce a substance that has a strong inibition activity against the Agkistrodon and Trimeresurus venoms. In this experiment, the chemical and biological properties of the sample were investigated. As an inhibitory substance, it was effective to the proteinase, hemorrhagic and lethal factors of Agkistrodon and Trimeresurus venoms, and also effective to several fractions of the proteinases and hemorrhagic factors of Agkistrodon halys blomhoffi venom. Moreover, in the addition of prednisotone, it was more effective for the cure of the mouse envenomated with the venom amount of two fold of MLD$_{100}$. This substance was very stable to the acid, alkali and heat. Its melting point was high enough to sublime at 222$^{\circ}C$ without any decomposition. This sample was easily dissolved only in hot water, but not in several organic solvents except for a little dissolution in elate. It did not have the chelating activity. It had very strong specificity to the snake venoms. but its activity was depressed by the addition of zinc or cupric salts. This sample had no acute toxicity to the mouse. Its chemical formula was $C_{16}$ $H_{12}$$N_2$ $O_{10}$ with the molecular weight of about 392. It has two epoxy groups and four carboxyl radicals, but amino, nitrite and nitrate radicals, unsaturated bonds and aromatic ring were not detected. Theuchemical configuration of this sample was suggested to be;

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