• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.98-107
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• 2004

The objectives of this research are to establish the criteria of peel occurrence considering the shape of bond terminus and to compare the strength properties of some adhesive joints. The criteria of feel occurrence at the bond terminus was suggested. Peel loads of some adhesive joint(butt joint, T -shape specimen, single lap joint) were determined from tensile tests. Principal stress distributions of these joints were determined from finite element method analysis. Then, peel occurrence was estimated with intensity of stress singularity ' $K_{prin.}$' when the terminus shape was square, with average principal stress when the terminus shape was rounded. The conclusions are summarized as follows; (1) In the non-filleted model(e.g., butt joint, T-shape specimen), principal stress shows singularity at the bond terminus, intensity of stress(principal stress) singularity ' $K_{prin.}$&apso; can use as the criteria of peel occurrence at the bond terminus. (2) In the filleted model(e.g., single lap joint), principal stress doesn't show singularity at the bond terminus. Average principal stress can use as the criteria of peel occurrence at the bond terminus.'t show singularity at the bond terminus. Average principal stress can use as the criteria of peel occurrence at the bond terminus.

• 대한소아치과학회지
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• 제28권1호
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• pp.45-53
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• 2001

레진 수복에서 초기에 저광도로 중합하여 레진의 유동성을 허용함으로써 중합시 내부응력을 상쇄하며, 다시 고광도로 중합하여 레진의 물성도 유지할 수 있는 방법이 시도되고 있어 초기 저광도 중합이 상아질과의 결합 강도와 레진의 미세경도에 미치는 영향을 알아보고자 하였다. 소의 건전한 하악 전치 20개를 3개의 절편으로 절단하여 각 군에 배분하고 상아질면에 레진을 충전한 후, I군은 $450mW/cm^2$의 광도도 40초간, II군은 $300mW/cm^2$와 $600mW/cm^2$의 광도로 각각 20초씩 III군은 $250mW/cm^2$와 $450mW/cm^2$에서 각각 20초씩 광중합하여 전단 결합 강도를 측정하였고, 직경 5.0mm깊이 2.0mm레진 시편을 제작하여 상, 하면 중앙에서 Vickers 미세 경도를 측정하였다. 전단결합 강도는 초기 저광도 중합군의 평균이 다소 높았으나 각 군간 통계학적 유의한 차이는 없었으며, 미세 경도는 상하면 모두에서 각 군간 통계학적으로 유의한 차이는 보이지 않았다.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2003년도 제120회 추계학술대회 제 5차 한ㆍ일 치과보존학회 공동학술대회
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• pp.576-577
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• 2003

I. Objectives This study investigated the dentin shear bond strength and the degree of conversion (DC) of currently used dentin bonding agents (DBAs) that were irradiated with a light emitting diode (LED) light curing unit (LCU) and a halogen LCU. II. Materials and methods The halogen LCU and the LED LCU used in this study were a VIP(Bisco, Schaumburg, IL, USA) and an Elipar Freelight(3M ESPE, St Paul, MN, USA) respectively. For the VIP, $400mW{\cdot}cm-2$ intensity mode was used to adjust to the intensity of the LED LCU. The DBAs used in this study were Scotchbond Multipurpose (3M ESPE), Single Bond (3M ESPE), One-step(Bisco), Clearfil SE Bond(Kuraray), and Adper Prompt(3M ESPE).(omitted)

• Journal of applied mathematics & informatics
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• 제31권5_6호
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• pp.711-732
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• 2013

In this paper, we are interested in finding explicit numerical formulas to evaluate defaultable bonds prices of firms. For this purpose, we use a default intensity whose values depend on the credit rating of these firms. Each credit rating corresponds to a state of the default intensity. Then, this regime switches as soon as one of the credit rating of a firm also changes. Moreover, this regime switching default intensity model allows us to capture well some market features or economics behaviors. Thus, we obtain two explicit different formulas to evaluate the conditional Laplace transform of a regime switching Cox Ingersoll Ross model. One using the property of semi-affine of the model and the other one using analytic approximation. We conclude by giving some numerical illustrations of these formulas and real data estimation results.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(5)
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• pp.123-126
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• 2001

This study presents the simulation of the traction return current based on 2${\times}$25kV power supply system in order to determine the impedance bond intensity of impulse type track circuit on the Kyoungbo electrification line. The results of simulation enables us to measure the precise intensity of catenary current, returning to the substation through KTX (Korean Train Express) operated by 2${\times}$25kV power supply system with common earth network. In the wake of establishing 2${\times}$25kV and common earth network used in Korea for the first time, in particular, it is possible to determine the impedance bond intensity of impulse type track circuit, which is applicable to the Kyoungbo electrification line by specifying the relations among the traction return current, earth current, and catenary current.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.99.5-99
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• 2001

This study presents a simulation of the traction return current based on $2{\times}25kV$ power supply system in order to determine the impedance bond intensity of impulse type track circuit on the electrified Gyeongbu line. The results of the simulation enables us to measure the precise intensity of catenary current that returns to the substation through KTX (Korean Train Express) operated by $2{\times}25kV$ power supply system with common earth network. The combination of $2{\times}25kV$ and common earth network established on the electrified Gyeongbu line for the first time in Korea. We show that the relationships among the traction return current, earth current, and catenary current, and catenary current can be applied to this line in order to determine the optimal impedance bond intensity ...

• Current Optics and Photonics
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• 제6권3호
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• pp.337-343
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• 2022

Microfluidic chips are new devices that can manipulate liquids at the micrometer level, and terahertz (THz) time-domain spectroscopy has good applicability in biochemical detection. The combination of these two technologies can shorten the distance between sample and THz wave, reduce THz wave absorption by water, and more effectively analyze the kinetics of biochemical reactions in aqueous solutions. This study investigates the effects of different external magnetic field intensities on the THz transmission characteristics of deionized water, CuSO₄, CuCl₂, (CH₃COO)₂Cu, Na₂SO₄, NaCl, and CH₃COONa; the THz spectral intensity of the sample solutions decrease with increasing intensity of the applied magnetic field. Analysis shows that the magnetic field leads to a change in the dipole moment of water molecules in water and electrolyte solutions, which enhances not only the hydrogen-bond networking ability of water but also the hydration around ions in electrolyte solutions, increasing the number of hydrogen bonds. Increasing the intensity of this magnetic field further promotes the hydrogen-bond association between water molecules, weakening the THz transmission intensity of the solution.

• Restorative Dentistry and Endodontics
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• 제26권5호
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• pp.409-417
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• 2001

상아질접착제의 광조사가 상아질접착에 미치는 영향을 알아보기 위하여 in vitro에서 접착실험을 하였다. 120개의 발거된 소의 전치 협면 상아질을 노출시키고 산 부식 한 다음 self-priming형 상아질접착제 Prime&Bond$^{\circledR}$NT (Dentsply DeTrey, GmbH, Konstanz, Germany)를 도포 하였으며 600 mW/$\textrm{cm}^2$의 일반광도 또는 1930 mW/$\textrm{cm}^2$의 초고광도 광조사를 각각 20초 및 3초간 시행한 군과 시행하지 않은 군으로 나누어 복합레진 첨가후 광조사하였다. 접착제에 대한 광조사를 시행하지 않은 경우에는 복합레진 첨가 후 초고광도로 3초, 6초 및 12초간 광조사하였다. 접착양상 평가를 위해 만능시험기로 전단접착강도를 측정하고 파단면을 입체 현미경으로 관찰한 바를 일원 및 이원 변량분석법과 카이제곱검사법으로 통계 분석하여 다음과 같은 결과를 얻었다. 1. 상아질접착제를 광조사한 군이 광조사하지 않은 군에 비해 유의하게 높은 전단접 착강도를 나타내었다 (p<0.05). 2. 일반 광도 및 초고광도 광조사에 따른 전단접착강도에는 유의한 차이가 나타나지 않았다 (p>0.05). 3. 상아질접착제를 광조사하지 않고 복합레진 첨가 후 초고광도로 광조사한 군간에 조사시간에 따른 전단접착강도에는 유의 한 차이가 나타나지 않았다 (p>0.05). 4. 파단면 관찰 결과, 모든 군에서 접착계면에서의 파절을 포함하는 혼합파단양상이 가장 많이 나타났으며 군간에는 유의한 차이가 없었다 (p>0.05).

• Journal of Photoscience
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• 제8권1호
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• pp.9-12
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• 2001

The photoisomerization behavior of benzylideneacetophenones, known as chalcones, was studied. We synthesized the chalcone derivatives that have ether groups at 4 and 4＇ positions. Due to the electron donating ability of the ether oxygen, the bond order of the single bond between two phenyl ring of the chalcone strengthened, which eventually increased the rotational barrier of the single bond. The rotational barrier of the single bond is about 20-22 kcal/mole. Thermal recovery of this process took about 1 min. The UV-visible spectra of these chromophores exhibit two characteristic absorption peaks at 276 nm and 340 nm. The relative intensity of the peaks varies depending on the alkyl chain length of the substituent. Photo-irradiation with the 365 nm light monotonously decreases the 340 nm peak. However, the photo-irradiation with 254 nm light induce two competing processes and produced rather complicated absorption profile.

• 한국공작기계학회논문집
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• 제14권5호
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• pp.62-73
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• 2005

The objects of this research are to establish the criteria of peel occurrence considering the shape of bond terminus and to compare the strength properties of adhesive joint of different three type such as butt joint, T-shape, and single lap Joints. The criteria of peel occurrence at the bond terminus was suggested. Peel loads of three type adhesive joint (butt Joint, T-shape specimen, single lap joint) were determined from tensile tests. Principal stress distributions of these joints were determined from finite element method analysis. Then, peel occurrence was estimated with stress singularity factor$(K_{prin})$ when the terminus shape was square, with average principal stress when the terminus shape was rounded. The conclusions are summarized as follows; (1) In the non-filleted model(e.g., butt joint, T-shape specimen), principal stress shows singularity at the bond terminus, intensity of stress(principal stress) singularity $(K_{prin})$ can use as the criteria of peel occurrence at the bond terminus. (2) In the filleted model(e.g., single lap joint), principal stress has not affected singularity at the bond terminus. Average principal stress$(K_{av})$ can use as the criteria of peel occurrence at the bond terminus.