• Title/Summary/Keyword: 다이 각

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배출원 주위 대기 중의 다이옥신 분포 및 배출원과의 관계

  • 오정은;최진수;양윤희;김병훈;장윤석
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 2000.04a
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    • pp.275-276
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    • 2000
  • 소각로에서 배출되는 다이옥신은 위해성 문제로 논란이 계속되고 있으며 현재 국내 도시 소각로의 경우 배출 기준치를 만족시켜야 하는 둥의 규제를 받고 있다. 또한 앞으로는 사업장소각로에서도 다이옥신 정기 측정이 의무화되는 등 배출원에서의 다이옥신 관리가 점차 더 강화될 예정이다. 이처럼 소각로에서 배출된 다이옥신은 대기 중 확산 및 이송과정에서 건·습식 침적과정을 통해 각 환경매체로 재분포되어 생물체에 농축 및 최종적으로는 인체로 유입되기도 한다. (중략)

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An experimental study on the effect of V-ring position and die chamfer shape on the die roll height in fine blanking tool (파인 블랭킹 금형의 V-링 위치 및 다이 챔퍼 형상이 다이 롤 높이에 미치는 영향에 관한 실험 연구)

  • Kim, Jong-Deok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.5
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    • pp.2009-2014
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    • 2012
  • It is very important to minimize the die roll height of gear, in order to maximize the shear cutting surface(tooth surface) of fine blanking. In this paper, the fine blanking tool sets were manufactured in order to study the die roll height according to V-ring position and die chamfer shape. They were constituted of the various die inserts and guide plate inserts with different die chamfer shape and different V-ring distance. The fine blanking experiment was conducted with the fine blanking tool sets and the die roll height of the gear samples was measured. It should be noted that die roll height on the fine blanked gear increased with increasing the V-ring distance and die chamfer angle.

Emission Characteristics of PCDD/Fs in MSW Incinerator(I) - The Effect of Air Pollution Control Device - (도시폐기물 소각공장에서의 다이옥신 배출특성(I) - 방지시설의 영향 -)

  • Kim, Jin-Beom;Lee, Woo-Keun
    • Journal of Korean Society of Environmental Engineers
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    • v.22 no.10
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    • pp.1817-1824
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    • 2000
  • This study is carried out to investigate the discharge characteristics of PCDD/Fs from municipal solid waste(MSW) incinerator, According to the results measured at several air pollution control devices(APCDs), the largest amount of polychlorinated dibenzo-p-dioxins/dibenzofurans(PCDD/Fs) are found at selective catalytic reduction (SCR) inlet. Therefore, it concludes that the electrostatic precipitator(EP) provides the appropriate condition for the formation of PCDD/Fs. The concentration of PCDD/Fs shows a large difference with the season. The concentration of PCDD/Fs in winter is higher than that of autumn, which suggests that the formation of PCDD/Fs is affected by the MSW components and the operation condition of municipal solid waste incinerator(MSWI).

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A Study on the Characteristics of Natural, Synthetic, and Treated Gem Quality Diamonds by NMR and EPR (NMR과 EPR을 이용한 천연, 합성, 그리고 처리된 보석용 다이아몬드의 특성 연구)

  • Kim, Jong-Rang;Jang, Yun-Deuk;Kim, Sun-Ha;Kim, Jong-Hwa;Paik, Youn-Kee
    • Journal of the Mineralogical Society of Korea
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    • v.21 no.4
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    • pp.435-442
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    • 2008
  • Natural, synthetic, and treated diamonds were studied by NMR and EPR. It was demonstrated that natural and synthetic diamonds, treated and non-treated diamonds, high pressure high temperature (HPHT) treated and electron beam treated diamonds could be distinguished among each other based on the $^{13}C$ NMR spectra acquired for relatively short periods of 100 minutes. The $^{13}C$ NMR linewidths of gem quality synthetic diamonds were broader than 1.6 ppm due to the paramagentic effects of transition metals, generally used as catalysts, while the linewidths of gem quality natural diamonds were narrower than 0.5 ppm regardless of the methods of treatment. The linewidth (0.5 ppm) for a HPHT treated, gem quality natural diamond was as broad as more than twice of the linewidth (0.2 ppm) of an electron beam treated diamond. The $^{13}C$ NMR signal intensities of treated, gem quality natural diamonds were as strong as more than 10 times of the intensities of non-treated, gem quality natural diamonds. When correlated with the concentrations of the paramagnetic defects (electrons) obtained from the EPR spectra, the relative $^{13}C$ NMR signal intensities increased in proportion to the concentrations of the paramagnetic electrons contained in each sample but the electron beam treated diamond was an exception. This suggested that the lattice component, in addition to the paramagnetic defect component, should also be considered in determining the $^{13}C$ NMR signal intensity of the electron beam treated diamond.

Multi Quantum Well 구조를 이용한 Red에서 Green으로의 energy transfer mechanism의 이해

  • Kim, Gang-Hun;Park, Won-Hyeok
    • Proceedings of the Korean Vacuum Society Conference
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    • 2015.08a
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    • pp.145-145
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    • 2015
  • 처음 유기물의 인광 발견 이후 Host-dopant 시스템을 이용하여 Emission layer(EML)을 Co-deopsition 하는 방법으로 주로 인광 유기 발광 다이오드를 제작 하였다. [1] co-deposition을 이용해 만든 유기 발광 다이오드에 많은 장점이 있지만, 반대로 소자를 제작하는데 있어서는 많은 문제점을 가지고 있다. [2-4] 이러한 문제점을 개선하기 위하여 co-deposition 대신 non-doped Multi Quantum Well(MQW) 구조를 사용하여 doping 하지 않는 방법을 이용하는 논문들이 보고 되고 있다. Hole, electron, exciton이 MQW 구조를 지나면서, dopant well 안에 갇히게 되고, 그 안에서 다른 layer 간에 energy transfer와, hole-electron leakage가 줄어 들어, 더 효율적인 유기 발광 다이오드를 만들 수 있게 된다. [5-7] 이 연구에서는 CBP를 Potential Barrier로 사용하고, Ir(ppy)3 (Green dopant), Ir(btp)2 (Red dopant) 를 각각 Potential Well로 사용하였고, 두께는 CBP 9nm, dopant 1nm로 하였다. 이러한 소자를 만들고 dopant를 3개의 well에 적당히 배치하여, 각 well에서의 실험적인 발광 량 과, EML 안에서의 발광 mechanism 그리고 각 potential barrier를 줄여가며 dexter, forster에 의한 energy transfer에 대하여 알 수 있었다.

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Sturcture-Property Relationship of a Liquid Crystalline Polymer (액정중합체의 구조.물성관계)

  • 서문호
    • The Korean Journal of Rheology
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    • v.4 no.2
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    • pp.99-106
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    • 1992
  • 전방향족 폴리에스테르계 열방성 액정중합체(Vectra A-950)를 대상으로 유로가 확 장되는 다이로의 압출을 통하여 액정 섬유상의 배향 특성을 조사하고 이들이 기계적 특성에 미치는 영향을 살펴보았다, 다이의 확장 효과에 의하여 중심에서는 유동방향과 수직방향으 로 섬유상이 이중 배향되었으며 가장자리에서는 주로 유동방향으로만 배향이 일어났다. 그 리고 배향 특성은 두께방향으로 상하 대칭성을 갖는 바깥 영역과 중간영역으로 구별되었으 며 겉층은 유동방향으로 배향되고 속층은 중심에서 멀어지면서 배향각이 점진적으로 달라졌 다. 이런한 시편의 기계적 강도는 압출다이의 확장각이 증가하거나 스크류 속도가 증가함으 로 따라 유동방향이나 그 수직방향 모두 현저한 증가를 보였으나 파단신도는 유동방향은 감 소하고 수직방향은 증가하여 증가하여 결과적으로 거의 비슷하였으며 파단신도가 배향상태 를 가장 잘 반영하는 기계적 특성임을 알 수 있었다.

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Effect of Die Angle in the Hydrostatic Extrusion of Copper-clad Aluminium Composites (Copper-clad Aluminium 복합재료의 정수압 압출시 다이 각이 미치는 효과)

  • 한운용;박훈재;윤덕재;정하국;김승수;김응주;이경엽
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.414-417
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    • 2003
  • A copper-clad aluminium composite bar is lighter and less expressive than a commercial copper alloy bar. Copper-clad aluminium composite bar can be fabricated by hot hydrostatic extrusion process. In this work, the effect of die angle on the compressive properties of copper-clad aluminium composites fabricated using hydrostatic extrusion process was investigated experimentally. The results showed that optimum half die angle was in the range of 40$^{\circ}$ to 50$^{\circ}$ for an extrusion ratio of 19. The results also showed that the half die angle had little influence on the compressive strength of copper-clad aluminium composites. A diffusion layer increased with increasing die angle.

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Study on terrestrial LIDAR transmitter designed to improve accuracy (측량용 레이저 스캐너의 정밀도 개선을 위한 송신부설계)

  • Yoo, Hyun-Kuk;Jeong, Jung-Yeon;Oh, Dong-Geun;Kim, Jae-Soon
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • 2009.04a
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    • pp.41-48
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    • 2009
  • Laser diode is used as a crucial part for minimization of terrestrial 3D Laser Scanner. But it has certain limitations such as oval beam shape and inevitable astigmatism. In order to realize a parallel light with beam divergence below 1 mrad, These problems of laser diode can be solved through beam shaping by Pinhole and Aperture. Finally, this study could materialize a collimated beam with 0.3 mrad beam divergence angle and 3mm diameter, that performance and checked by using real manufacture.

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Comparison of the retention of the full veneer casted gold crowns with varying convergence angle, crown length and dental cements (수렴각과 치관 길이를 달리한 금속 다이상에서 치과용 시멘트 합착 후 전부주조관의 유지력 비교)

  • Yun, Jung-Ho;Cho, Jin-Hyung;Kim, Jee-Hwan;Lee, Keun-Woo
    • The Journal of Korean Academy of Prosthodontics
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    • v.51 no.2
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    • pp.99-106
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    • 2013
  • Purpose: The aim of this research was to establish the effect and variation in differing convergence angle and length of abutment on the retention of full veneer casted gold crown. Materials and methods: Two different length,5 mm and 10 mm in height with convergence angles of 5, 10, 15 and 25 degrees crowns were fabricated. Cementation was done using cements; zinc phosphate cement (Fleck's zinc phosphate cement), resin-modified glass ionomer cement (Vitremer) and resin cement (Panavia 21). These were tested for tensile force at the point of separation by using Instron Universal Testing Machine. Statistical analysis was done by SAS 6.04 package. Results: In all cements the mean retention decreased with significant difference on increase of convergence angle (P<.05). Increase in every 5 degree-convergence angel the retention rate decreased with resin-modified glass ionomer cement of 15.9% and resin cement of 14.8%. With zinc phosphate cement, there was largest decreasing rate of mean retention of 25.5% between convergence angles from 5 degree to 10 degree. When the crown length increased from 5 mm to 10 mm, the retention increased with the significant difference in the same convergence angle and in all types of cement used (P<.05). Conclusion: The retention was strongly dependent on geometric factors of abutment. Much care is required in choosing cements for an optimal retention in abutments with different convergence angles and crown lengths.

Accuracy of dies fabricated by various three dimensional printing systems: a comparative study (다양한 삼차원 프린팅 시스템으로 제작된 다이의 정확도 비교)

  • Baek, Ju Won;Shin, Soo-Yeon
    • Journal of Dental Rehabilitation and Applied Science
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    • v.36 no.4
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    • pp.242-253
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    • 2020
  • Purpose: The aim of this study was to compare the accuracy of dies fabricated using 3D printing system to conventional method and to evaluate overall volumetric changes by arranging the superimposed surfaces. Materials and Methods: A mandibular right first molar from a dental model was prepared, scanned and fabricated with composites of polyetherketoneketone (PEKK). Master dies were classified into 4 groups. For the conventional method, the impression was taken with polyvinylsiloxane and the impression was poured with Type IV dental stone. For the 3D printing, the standard die was scanned and converted into models using three different 3D printers. Each of four methods was used to make 10 specimens. Scanned files were superimposed with the standard die by using 3D surface matching software. For statistical analysis, Kruskal-Wallis test and Mann-Whitney U test were done (P < 0.05). Results: Compared to the standard model, the volumetric changes of dies fabricated by each method were significantly different except the models fabricated by conventional method and 3D printer of Stereolithography (P < 0.05). The conventional dies showed the lowest volumetric change than 3D printed dies (P < 0.05). 3D printed dies fabricated by Stereolithography showed the lowest volumetric change among the different 3D printers (P < 0.05). Conclusion: The conventional dies were more accurate than 3D printed dies, though 3D printed dies were within clinically acceptable range. Thus, 3D printed dies can be used for fabricating restorations.