• Title/Summary/Keyword: melting time

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Comparison of Shear Bond Strength of Veneer Ceramics to Co-Cr Alloys Produced by Selective Laser Melting and Casting Technique (선택적 레이저 용융 그리고 전통적인 주조 기술에 의해 제조된 Co-Cr 합금에 대한 전장용 세라믹의 전단 결합 강도 비교)

  • Hong, Min-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.12
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    • pp.434-439
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    • 2020
  • Selective laser melting (SLM) manufactures an alloy using laser as a heat source, and has recently been introduced in the dental industry. However, there is a lack of analytical research on metal-ceramic restorations achieved by SLM. This study evaluates and compares the metal-ceramic bond strength of Co-Cr alloys produced by selective laser melting and casting methods. Co-Cr samples required for this study were produced through the sintering process of ceramics, by applying the SLM and CAST methods. The metal-ceramic bond strength was measured by applying the shear bond strength test. In order to determine the area fraction of adherent ceramic, Si content of the specimen was measured using scanning electron microscopy SEM/ EDS. Results of the metal-ceramic bond strength and AFAC were analyzed by t-test (α = 0.05). No significant difference was observed comparing the bond strength of SLM and CAST Co-Cr alloys (P> 0.05). However, the SLM group had much better ceramic adherence than the CAST group (P < 0.001). Moreover, oxidation characteristics were similar for both SLM and CAST Co-Cr alloys, but metal structures were different. These results imply that although the bond of ceramic and Co-Cr alloy is not related to the manufacturing method, SLM alloys impart better ceramic adherence. This indicates that alloys made with SLM can be used to fabricate upper implant prostheses in the future. In particular, it is expected to overcome the shortcomings of the CAST method, and save time and cost.

Effects of Freeze Dry Control Parameters on the Sublimation Drying Time of Garlic paste (동결건조 제어변수가 마늘의 승화건조시간에 미치는 영향)

  • Park, N.H.;Bae, S.C.
    • Journal of Biosystems Engineering
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    • v.18 no.2
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    • pp.122-132
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    • 1993
  • Effects of physical properties of garlic paste and freeze dry control parameters on the sublimation drying time were investigated to verify optimal operating method in freeze drying. A mathematical model of freeze drying by sublimation was suggested and used to estimate the drying time of garlic paste. Under various conditions, the drying time of garlic paste was calculated using the computer program for the suggested model. Among the physical properties of garlic paste, melting temperature was evaluated the most important factor in affecting the drying time. In supplying methods of the required heat energy for sublimation, it would be the best way to control the upper plate temperature and the lower plate temperature independently.

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Variations of Mechanical Properties and Corrosion Rate with Melting Conditions and Alloying Elements in High Silicon Cast Irons (용해조건 및 합금원소 첨가에 따른 고규소 내산주철의 기계적 성질 및 부식속도의 변화)

  • Kim, Jung-Chul;Han, Dong-Woon;Baik, Jin-Hyun;Baik, Seung-Han;Moon, Byung-Moon;Shin, Je-Sik;Lee, Young-Kuk
    • Journal of Korea Foundry Society
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    • v.24 no.4
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    • pp.209-216
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    • 2004
  • High silicon cast irons(HSCI) with the high acid resistance have been used for the prevention of acid corrosion occurring in various structures under acid conditions. However, the HSCI is only known as one of materials which have high acid resistance, but few work has dealt with this material in domestic. Therefore, in this study, the acid resistance of various cast irons with alloying elements and melting conditions have been examined, and studied the influences of the matrix structures, mechanical properties and morphologies of graphite. The results obtained in this study are as follows : In case of melting temperature, the mechanical properties of specimen manufactured with high temperature of 1650C showed higher value because the inclusion and impurity were removed. In case of pouring temperature, the mechanical properties of specimen fabricated below 1350C of pouring temperature showed higher value because the amount of gas absorption from atmosphere decreased during the solidification time. The corrosion rate decreased with increase in Si content. On the other hand, Mn addition appeared an opposite trend with Si.

Internal Transcribed Spacer Barcoding DNA Region Coupled with High Resolution Melting Analysis for Authentication of Panax Species (DNA 바코딩과 고해상 융해곡선분석에 기반한 인삼속 식물의 종 판별)

  • Bang, Kyong Hwan;Kim, Young Chang;Lim, Ji Young;Kim, Jang Uk;Lee, Jung Woo;Kim, Dong Hwi;Kim, Kee Hong;Jo, Ick Hyun
    • Korean Journal of Medicinal Crop Science
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    • v.23 no.6
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    • pp.439-445
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    • 2015
  • Background : Correct identification of Panax species is important to ensure food quality, safety, authenticity and health for consumers. This paper describes a high resolution melting (HRM) analysis based method using internal transcribed spacer (ITS) and 5.8S ribosomal DNA barcoding regions as target (Bar-HRM) to obtain barcoding information for the major Panax species and to identify the origin of ginseng plant. Methods and Results : A PCR-based approach, Bar-HRM was developed to discriminate among Panax species. In this study, the ITS1, ITS2, and 5.8S rDNA genes were targeted for testing, since these have been identified as suitable genes for use in the identification of Panax species. The HRM analysis generated cluster patterns that were specific and sensitive enough to detect small sequence differences among the tested Panax species. Conclusion : The results of this study show that the HRM curve analysis of the ITS regions and 5.8S rDNA sequences is a simple, quick, and reproducible method. It can simultaneously identify three Panax species and screen for variants. Thus, ITS1HRM and 5.8SHRM primer sets can be used to distinguish among Panax species.

Application of LATE-PCR to Detect Candida and Aspergillus Fungal Pathogens by a DNA Hybridization Assay

  • Gopal, Dhayaalini Bala;Lim, Chua Ang;Khaithir, Tzar Mohd Nizam;Santhanam, Jacinta
    • Microbiology and Biotechnology Letters
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    • v.45 no.4
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    • pp.358-364
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    • 2017
  • Asymmetric PCR preferentially amplifies one DNA strand for use in DNA hybridization studies. Linear-After-The-Exponential-PCR (LATE-PCR) is an advanced asymmetric PCR method which uses innovatively designed primers at different concentrations. This study aimed to optimise LATE-PCR parameters to produce single-stranded DNA of Candida spp. and Aspergillus spp. for detection via probe hybridisation. The internal transcribed spacer (ITS) region was used to design limiting primer and excess primer for LATE-PCR. Primer annealing and melting temperature, difference of melting temperature between limiting and excess primer and concentration of primers were optimized. In order to confirm the presence of single-stranded DNA, the LATE-PCR product was hybridised with digoxigenin labeled complementary oligonucleotide probe specific for each fungal genus and detected using anti-digoxigenin antibody by dot blotting. Important parameters that determine the production of single-stranded DNA in a LATE-PCR reaction are difference of melting temperature between the limiting and excess primer of at least 5C and primer concentration ratio of excess primer to limiting primer at 20:1. LATE-PCR products of Candida albicans, Candida parapsilosis, Candida tropicalis and Aspergillus terreus at up to 1:100 dilution and after 1 h hybridization time, successfully hybridised to respective oligonucleotide probes with no cross reactivity observed between each fungal genus probe and non-target products. For Aspergillus fumigatus, LATE-PCR products were detected at 1:10 dilution and after overnight hybridisation. These results indicate high detection sensitivity for single-stranded DNA produced by LATE-PCR. In conclusion, this advancement of PCR may be utilised to detect fungal pathogens which can aid the diagnosis of invasive fungal disease.

Preparation and Thermal Properties of Octadecane/xGnP Shape-Stabilized Phase Change Materials to Improve the Heat Storage Performance of Buildings (건축물 축열성능 향상을 위한 Octadecane/xGnP SSPCM 제조 및 열적성능 분석)

  • Kim, Sughwan;Jeong, Su-Gwang;Lee, Jeong-Hun;Kim, Sumin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.3
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    • pp.126-130
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    • 2013
  • In this study, a shape-stabilized phase change material (SSPCM) was prepared by octadecane and exfoliated graphite nanoplate (xGnP) in a vacuum, to improve thermal storage performance. The octadecane as an organic phase change material (PCM) is very stable against phase separation of PCM, and has the proper temperature range for thermal comfort in the building; and the xGnP is a porous carbon nano-material. Scanning electron microscope (SEM) and Fourier transformation infrared spectrophotometer (FT-IR) were used to confirm the chemical and physical stability of the Ocatadecane/xGnP SSPCM. In addition, thermal properties were determined by Deferential scanning calorimeter (DSC), and Thermogravimetric analysis (TGA). The specific heat of Octadecane/xGnP SSPCM was 14.1J/gK at 31.3C. The melting temperature ranges of melting and freezing were found to be 2635C and 2619C, respectively. At this time, the latent heats of melting and freezing were 110.9 J/g and 104.5 J/g, respectively. The Octadecane was impregnated into xGnP by as much as about 56.0% of the Octadecane/xGnP SSPCM's mass fraction.

Thermo-Mechanical Analysis of Continuous-Adjustment Thruster using Explosion Pressure (폭압을 사용하는 연속조정 추진구조체의 열-구조해석)

  • Kim, Kyung-Sik;Kwon, Young-Doo;Kwon, Soon-Bum;Gil, Hyuck-Moon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.6
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    • pp.699-705
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    • 2011
  • High-maneuver missile is a projectile which demands a strong momentum at short time. To produce a necessary thrust for the flight, the gas of high temperature and pressure is generated through explosive combustion of solid propellant, and a great thrust can be obtained by expanding this high temperature and pressure gas. Although the operating time of a rocket motor is less than a few seconds, a failure of part or ablation near the throat of nozzle may take place during the expansion of high temperature and pressure gas for great thrust. In other words, for the precise control of a missile an exact stress analysis considering both, the thermal stress caused by the heat transfer between combustion gas and wall, and the mechanical stress caused by the pressure change in the flow, should be considered first. In this connection, this study investigated the safety, as a point of view of stress and melting point of the material, of the pre-designed thrust generating structure which is subjected to high temperature and pressure as a function of motor operating time.

Development of Automatic Filling Process for Rapid Manufacturing by High-speed Machining Process (고속가공에 의한 쾌속제작용 자동충진 공정개발)

  • 신보성;양동열;최두선;이응숙;제태진;김기돈;이종현;황경현
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.28-31
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    • 2001
  • Recently, in order to satisfy the consumer's demand the life cycle and the lead-time of a product is to be shortened. It is thus important to reduce the time and cost in manufacturing trial products. Several techniques have been developed and successfully commercialized in the market RPM(Rapid Prototyping and Manufacturing). However, most commercial systems currently use resins or waxes as the raw materials. So, the limited mechanical strength for functional testing is regarded as an obstacle towards broader application of rapid prototyping techniques. To overcome this problems, high-speed machining technology is being investigated worldwide for rapid manufacturing and even for direct rapid tooling application. In this paper, some fundamental experiments and analyses are carried out to obtain the filling time, materials, method, and process parameters for HisRP process. HisRP is a combination process using high-speed machining technology with automatic filling. In filling process, Bi58-Sn alloy is chosen because of the properties of los-melting point, low coefficient of thermal expansion and enviromental friendship. Also the use of filling wire is of advantage in term of simple and flexible mechanism. Then the rapid manufacturing product, for example a skull, is machined for aluminum material by HisRP process with an automatic set-up device of 4-faces machining.

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The effect of Er:YAG laser irradiation on the surface microstructure and roughness of hydroxyapatite-coated implant

  • Kim, Seong-Won;Kwon, Young-Hyuk;Chung, Jong-Hyuk;Shin, Seung-Il;Herr, Yeek
    • Journal of Periodontal and Implant Science
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    • v.40 no.6
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    • pp.276-282
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    • 2010
  • Purpose: The present study was performed to evaluate the effect of erbium:yttrium-aluminium-garnet (Er:YAG) laser irradiation on the change of hydroxyapatite (HA)-coated implant surface microstructure according to the laser energy and the application time. Methods: The implant surface was irradiated by Er:YAG laser under combination condition using the laser energy of 100 mJ/pulse, 140 mJ/pulse and 180 mJ/pulse and application time of 1 minute, 1.5 minutes and 2 minutes. The specimens were examined by surface roughness evaluation and scanning electron microscopic observation. Results: In scanning electron microscope, HA-coated implant surface was not altered by Er:YAG laser irradiation under experimental condition on 100 mJ/pulse, 1 minute. Local areas with surface melting and cracks were founded on 100 mJ/pulse, 1.5 minutes and 2 minutes. One hundred forty mJ/pulse and 180 mJ/pulse group had surface melting and peeling area of HA particles, which condition was more severe depending on the increase of application time. Under all experimental condition, the difference of surface roughness value on implant surface was not statistically significant. Conclusions: Er:YAG laser on HA-coated implant surface is recommended to be irradiated below 100 mJ/pulse, 1 minute for detoxification of implant surface without surface alteration.

Variation in Properties of Seawater Flooded and Non-Flooded CSPE (해수범람 전·후의 CSPE 특성변화)

  • Lee, Jeong-U;Kim, In-Yong;Ji, Seong-Hyun;Jeon, Hwang-Hyun;Shin, Yong-Deok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.12
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    • pp.1724-1729
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    • 2015
  • Chlorosulfonated polyethylene (CSPE) was not flooded seawater and flooded seawater & freshwater for 5 days, respectively, and these samples are referred to as BSF(before seawater flooding) and ASFF(after seawater & freshwater flooding), respectively. The apparent density, dissipation factor, relative permittivity, melting temperature, dielectric breakdown time and increased time of applied voltage are higher than those of BSF, but the insulating resistance, dielectric strength, percent elongation and glass transition temperature of ASFF are lower than those of BSF. The differential temperature of those is 0.0260.028(C) after AC and DC voltage is applied to ASFF, respectively, and the differential temperature of those is 0.0130.037(C) after AC and DC voltage is applied to BSF, respectively. In the case AC and DC voltage is applied to ASFF as well as BSF, the variations in temperature of AC voltage are higher than those of DC voltage. It is investigated that dielectric loss due to dissipation factor (tanδ) is related to electric dipole conduction current. It is certain that the ionic (electron or hole) leakage current was increased by conducting ions such as Na+, Cl, Mg2+, SO24, Ca2+ and K+, those are related to cured atoms of O and S that relatively increased after seawater flooding.