• 제목/요약/키워드: Bonding Phenomena

검색결과 76건 처리시간 0.022초

A Naked Eye Detection of Fluoride with Urea Receptors Which have both an Azo Group and a Nitrophenyl Group as a Signaling Group

  • Dang, Nhat Tuan;Park, Jin-Joo;Jang, Soon-Min;Kang, Jong-Min
    • Bulletin of the Korean Chemical Society
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    • 제31권5호
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    • pp.1204-1208
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    • 2010
  • Anion recognition via hydrogen-bonding interactions could be monitored with changes in UV-vis absorption spectra and in some cases easily monitored with naked eye. Urea receptors 1 and 2 connected with both an azo group and a nitrophenyl group as a signaling group for color change proved to be an efficient naked eye receptor for the fluoride ion. The anion recognition phenomena of the receptors 1 and 2 via hydrogen-bonding interactions were investigated through UV-vis absorption and $^1H$ NMR spectra.

박테리아 셀룰로오스 시트의 물성에 미치는 충전제의 첨가효과 (Effect of Filler Addition on Properties of Sheets Prepared from Bacterial Cellulose)

  • 조남석;민두식
    • 펄프종이기술
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    • 제30권4호
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    • pp.35-41
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    • 1998
  • The bacterial cellulose has many unique properties that are potentially and commercially beneficial. In order to make opaque product from this cellulose, filling properties by fillers should be known. This study was performed to investigate the effect of filler addition on physical properties of sheets from bacterial cellulose. The effect of filling on its optical properties was also discussed. The apparent density and internal bonding strength of bacterial cellulose sheet are decreasing with the increase of filler contents. Those adversely affect Young's modulus and physical property of the sheet, but these negative phenomena of the bacterial cellulose sheet by filler addition are not so sensitive compared to substantial decreasing of physical properties of ordinary hardwood KP. This strength decrease would be attributed to the decrease of relative bonding sites among pulp fibers. Concerned to optical properties, the bacterial cellulose sheet shows high increase of brightness and opacity according to filler loading, but no significant changes in porosity up to 17.3% loading because of fine and filamentous structure of bacterial cellulose fibers.

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이종 전자재료 JO1NT 부위의 신뢰성에 관한 연구 (A Study on Reliability of Solder Joint in Different Electronic Materials)

  • 신영의;김경섭;김형호
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1993년도 추계학술대회 논문집
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    • pp.49-54
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    • 1993
  • This paper discusses the reliability of solder joints of electronic devices on printed circuit board. Solder application is usually done by screen printing method for the bonding between outer leads of devices and thick film(Ag/Pd) pattern on Hybrid IC as wel1 as Cu lands on PCB. As result of thermal stresses generated at the solder joints due to the differences of thermal expansion coefficients between packge body and PCB, Micro cracking often occurs due to thermal fatigue failure at solder joints. The initiation and the propagate of solder joint crack depends on the environmental conditions, such as storage temperature and thermal cycling. The principal mechanisms of the cracking pheno- mana are the formation of kirkendal void caused by the differences in diffusion rate of materials, ant the thermal fatigue effect due to the differences of thermal expansion coefficient between package body and PCB. Finally, This paper experimentally shows a way to supress solder joints cracks by using low-${\alpha}$ PCB and the packages with thin lead frame, and investigates the phenomena of diffusion near the bonding interfaces.

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브레이징한 2상 스테인리스강 UNS32550의 미세조직 및 기계적 특성 (Microstructure and Mechanical Property of Brazed Joint in Duplex Stainless Steel, UNS32550)

  • 김대업;강정윤
    • Journal of Welding and Joining
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    • 제21권2호
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    • pp.64-69
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    • 2003
  • The bonding phenomena and mechanical property of duplex stainless steel during brazing have been investigated. The UNS32550 was used for base metal, and the MBF50 was used for insert metal. Brazing was carried out under the various conditions (brazing temperature : 1473K, 1498K, holding time : 0∼1.8ks). There were various microconstituents in the bonded interlayer because of reaction between liquid insert metal and base metal. In the early stage of brazing, BN is formed in the bonded interlayer and base metal near the bonded layer. Cr made is formed in the bonded interlayer. The amount of BN and Cr nitrides decrease with the increase of bonding temperature and holding time. Superior shear strength of 550MPa is obtained by restraining the formation of nitrides. (Received January 17, 2003)

Carbon/Epoxy 복합재료 구조물의 층간강도 향상 연구 (Study on the Improvement of Inter-laminar Bonding Strength of Carbon/Epoxy Composite Structures)

  • 최재호;송흥섭;박인서;박승범;황병선
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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    • pp.161-164
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    • 2004
  • In these days, composite materials are applied to the military field like parts of air crafts, rockets, ammunitions and so on. As high pressure is loaded on the composite body, however, cracks or delamination phenomena can be occurred between layers of laminate. These cracks or delamination usually cause a deterioration of mechanical properties under the complicated loads. In this study, methods for improvement of the inter-laminar bonding strength of thick carbon/epoxy composite structures are suggested and discussed in terms of segment bending test.

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텅스텐-알루미나 접합거동에 미치는 산소분압의 영향 (Effect of Oxygen Partial Pressure on Tungsten-Alumina Bonding Behavior)

  • 박정현;이상진
    • 한국세라믹학회지
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    • 제27권6호
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    • pp.755-762
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    • 1990
  • The tungsten paste was printed on the surface of 92% alumina sheet which was made by type casting process. The printed tungsten was bonded on the Al2O3 by co-firing in reducing atmosphere. During the co-firing, the binder burn-out was easier in wet H2 atmosphere than in dry H2, which affected sintered density. In practically, the use of wet H2 above 100$0^{\circ}C$ was beneficial for density of alumina and bond strength. This phenomena occured more distinctly when atmosphere varied from dry H2 to wet H2 than varied dew point in wet H2. In wet H2, the improvement in bonding strength can be attributed to good glass migration into the metal layer due to inhibition of the tungsten particle growth, with increase of alumina density, at the temperatrue higher than 100$0^{\circ}C$.

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비귀금속 박막이 치과용합금과 치과용도재와의 화학적결합에 미치는 영향 (EFFECTS OF SPUTTERED NON-PRECIOUS METALLIC THIN FILMS ON THE CHEMICAL BONING BETWEEN DENTAL ALLOY AND PORCELAIN)

  • 조성암
    • 대한치과보철학회지
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    • 제30권4호
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    • pp.481-492
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    • 1992
  • Author measured the bonding strength between Dental Porcelain and Nonprecious Dental Alloy and analyzed diffusion Phenomena at the interfaceby by Auger electron spectroscopy and also Electron spectroscopy for Chemical Analysis. The each specimen was sputtered with Al, Cr, In and Sn. 1. Ni whic is the main element of the matris of dental nonprecious alloy diffuse more than the other element and the Ni diffusion rate of each specimen was well coordinated with the bonding strength of each. 2. The Sn thin film suppress the diffusion rate of Ni of matrix into the Dental Porcelain than the In or Cr thin films. 3. The Al thin film suppress the diffusion rate of Ni than the Sn thin film. 4. The main coponent of dental porcelain : Al, Si, Mo diffused into the matrix of alloy. It means that the each element of dental alloy and dental porelain diffused into the each other part.

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A Novel Body-tied Silicon-On-Insulator(SOI) n-channel Metal-Oxide-Semiconductor Field-Effect Transistor with Grounded Body Electrode

  • Kang, Won-Gu;Lyu, Jong-Son;Yoo, Hyung-Joun
    • ETRI Journal
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    • 제17권4호
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    • pp.1-12
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    • 1996
  • A novel body-tied silicon-on-insulator(SOI) n-channel metal-oxide-semiconductor field-effect transistor with grounded body electrode named GBSOI nMOSFET has been developed by wafer bonding and etch-back technology. It has no floating body effect such as kink phenomena on the drain current curves, single-transistor latch and drain current overshoot inherent in a normal SOI device with floating body. We have characterized the interface trap density, kink phenomena on the drain current ($I_{DS}-V_{DS}$) curves, substrate resistance effect on the $I_{DS}-V_{DS}$ curves, subthreshold current characteristics and single transistor latch of these transistors. We have confirmed that the GBSOI structure is suitable for high-speed and low-voltage VLSI circuits.

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고속철도 콘크리트궤도-자갈도상궤도 완충구간의 뜬침목 발생 현상과 대책 (Unsupported Sleepers in Transition Zone between Concrete Slab Track and Ballasted Track : Phenomena and Its Countermeasures)

  • 장승엽;임오진;양신추
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2007년도 추계학술대회 논문집
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    • pp.1126-1131
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    • 2007
  • In 1st Phase Kyeong-Bu High-Speed Line, to lessen the impact in the transition zone between concrete slab track(in tunnel) and ballasted track(on embankment), the ballast bonding method has been adopted. However, in this area, in the beginning of the operation, unsupported sleepers are found, and the track deterioration and damage of concrete sleepers have occurred. In this paper, the status and causes of unsupported sleepers are discussed and several repair measures are proposed.

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Comparison of Pervaporation and Vapor Permeation Separation Processes for MTBE-methanol System

  • Kim, Youn-Kook;Lee, Keun-Bok;Rhim, Ji-Won
    • Korean Membrane Journal
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    • 제2권1호
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    • pp.36-47
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    • 2000
  • This paper deals with the separation of MTBE-methanol mixtures using crosslinked Poly(vinyl alcohol)(PVA) membranes with sulfur-succinic acid(SSA) as a crosslinking agent by pervaporation and vapor permeation technique. The operating temperatures, methanol concentration in feed mixtures, and SSA concentrations in PVA membranes were varied to investigate the separation performance of PVA/SSA membranes and the optimum separation characteristics by pervaporation and vapor permeation. And also, for PVA/SSA membranes, the swelling measurements were carried out to study the transport phenomena. The swelling measurements were carried out for pure MTBE and methanol, and MTBE/methanol=90/10, 80/20 mixtures using PVA/SSA membranes with varying SSA compositions. There are two factors of the membrane network and the hydrogen bonding. In pervaporation separation was also carried out for MTBE/methanol=90/10, 80/20 mixtures at various temperatures. The sulfuric acid group in SSA took an important role in the membrane performance. The crosslinking effect might be over the hydrogen bonding effect due to the sulfuric acid group at 3 and 5% SSA membranes, and this two factors act vice versa on 7% SSA membrane. In this case, the 5% SSA membrane shows the highest separation factor of 2,095 with the flux of 12.79g/㎡$.$hr for MTBE/methanol=80/20 mixtures at 30$^{\circ}C$ which this mixtures show near the azeotopic composition. Compared to pervaporation, vapor permeation showed less flux and similar separation factor. In this case, the flux decreased significantly because of compact structure and the effect of hydrogen bonding. In vapor permeation, density or concentration of methanol in vaporous feed is lower than that of methanol in liquid feed, as a result, the hydrogen bonding portion between the solvent and the hydroxyl group in PVA is reduced in vapor permeation. In this case, the 7% SSA membranes shows the highest separation factor of 2,187 with the flux of 4.84g/㎡$.$hr for MTBE/methanol=80/20 mixtures at 30$^{\circ}C$.

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