• Mass Spectrometry Letters
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• v.14 no.3
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• pp.110-115
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• 2023

The reaction of (COD)PdCl₂ with new C₃-symmetric tridentate L (COD = 1,5-cyclooctadien; L = 1,3,5-tris(picolinoyloxyethyl)cyanurate) in a mixture of acetone and dichloromethane produces single crystals consisting of unprecedented monometallacyclic [PdCl₂(L)]. This cyclic compound arises from trans-chelation of two of three donating pyridyl groups of L, while the third pyridyl group remains uncoordinated. Electrospray ionization mass spectrometry (ESI-MS) data on L exhibited the major peak corresponding to [C₂₇H₂₄N₆O₉ + H⁺]⁺. Fast atom bombardment mass spectrometry (FABMS) data on [PdCl₂(L)], however, showed the mass peak corresponding to the L instead of the present palladium(II) compound species, due to the insolubility and dissociation in solution. The physicochemical properties of the present palladium(II) compound were fully characterized by means of infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy, thermal analysis, single-crystal X-ray diffraction (SC-XRD) measurement.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.99.1-99.1
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• 2015

ALD와 CVD 공정을 진행 하는데 있어서 전구체의 평가 및 실시간 분해과정을 확인 하는 것은 매우 중요하다. 본 실험에서는 고유전 산화막에 쓰이는 Cyclopentadienyl Tris (dimethylamino) Zirconium, CpZr(NMe2)3 전구체의 증기압 특성과 FTIR, QMS를 활용하여 $250^{\circ}C$ 온도구간 에서의 분해과정을 실시간으로 측정 하였다. CpZr(NMe2)3의 Atomic mass 는 288 amu이며 증기압은 $60^{\circ}C$에서 0.075 Torr로 측정되었다. 온도가 증가 함에 따라 FTIR 에서 CH3 symmetric stretch (2776 cm-1), CH3 symmetric stretch (2865 cm-1) intensity가 줄어 들게 되었으며 QMS에서도 15 amu (Methyl)의 신호가 온도가 증가함에 따라 감소함을 확인 할수 있었다. QMS에서 Cp의 이온전류가 사라진 이유는 Cp가 모체인 CpZr에서 모두 다 분리되었고 신호가 없어 졌기 때문이다. 본 연구를 통해서 FTIR 단독으로는 얻을수 없는 온도에 따른 세부적인 분해과정을 QMS로 실시간 측정 함으로서 FTIR의 분석 결과와 산호보완 할수 있게 되었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.2
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• pp.217-224
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• 2002

It is very important to measure and visualize the changes in the physical properties of fluid flow because this is the foundation of measurement techniques used in aerodynamics, heat transfer, plasma diagnostics, and stress analysis of transparent models. The optical methods are advantageous over probe-based techniques in the optical methods are of high speed, non-contact and are capable of providing full-field results with high spatial resolution. Therefore we propose the electronic speckle pattern interferometry(ESPI) that gives us a solution to overcome those limitations. In this paper the experimental results show qualitative and quantitative visualization of changes in the physical properties of the candle and alcohol lamp with 3D plotting. And we obtained the refractive index, mass density and temperature distribution of fluids. The results clearly show the process of flow phenomena and give the feasibility of quantitative interpretation of gasdynamics.

• Earthquakes and Structures
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• v.8 no.1
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• pp.77-100
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• 2015

Multiple tuned mass dampers (MTMDs) tuned to various frequencies have been shown to efficiently control the seismic response of structures where multiple modes are dominant. One example is irregular structures that are found more vulnerable than their symmetric counterparts. With the technology of MTMDs available, design and optimal design methodologies are required for application. Such a methodology, in the form of an analysis/redesign (A/R) scheme, has been previously presented by the authors while limiting responses of interest to allowable values, i.e., performance-based design (PBD). In this paper, the A/R procedure is modified based on formal optimality criteria, making it more cost efficient, as well as more computationally efficient. It is shown that by using the methodology presented herein, a desired performance level is successfully targeted by adding near-optimal amounts of mass at various locations and tuning the TMDs to dampen several of the structure's frequencies. This is done using analysis tools only.

• Geomechanics and Engineering
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• v.6 no.3
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• pp.213-233
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• 2014

The present paper is dealing with the investigation of the stress field around the infinitely long cylindrical cavity, of a circular cross section, contained in the transversally isotropic elastic continuum. Investigation is based upon the determination of the stress function that satisfies the biharmonic equation, for the given boundary conditions and for rotationaly symmetric loading. The solution of the partial differential equation of the problem is given in the form of infinite series of Bessel's functions. Determination of the stress-strain field around cavities is a common requirement for estimation of safety of underground rock excavations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.418-421
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• 2001

The ceramic filters were developed using technology similar to that of quartz crystal and electro- mechanical filter. However, the key to this development involved the theoretical analysis of vibration modes and material improvements of piezoelectric ceramics. The primary application of ceramic filters has been for consumer-market use. Accordingly, a major emphasis has involved mass production technology, leading to low-priced devices. A typical ceramic filter includes monolithic resonators and capacitors packaged in unique configurations. Nakazawa developed a double-mode resonator as two acoustically coupled single resonators. And he developed 10.7MHz crystal filters using multi-energy trapping mode of thickness shear vibration. He succeeded in realizing a two-pole band pass filter response without external inductance by splitting a dot electrode to creak coupled symmetric and anti- symmetric vibration modes. Accordingly, the simulation for ceramic (inter were important. So that, this paper were investigated the pass frequency of filter on the electrode length and thickness of ceramic.

• Wind and Structures
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• v.5 no.5
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• pp.407-422
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• 2002

Passive control of the flutter condition of suspension bridges using a combined vertical and torsional tuned mass damper (TMD) system is presented. The proposed TMD system has two degrees of freedom, which are tuned close to the frequencies corresponding to vertical and torsional symmetric modes of the bridge which get coupled during flutter. The bridge-TMD system is analyzed for finding critical wind speed for flutter using a finite element approach. Thomas Suspension Bridge is analyzed as an illustrative example. The effectiveness of the TMD system in increasing the critical flutter speed of the bridge is investigated through a parametric study. The results of the parametric study led to the optimization of some important parameters such as mass ratio, TMD damping ratio, tuning frequency, and number of TMD systems which provide maximum critical flutter wind speed of the suspension bridge.

• Smart Structures and Systems
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• v.18 no.5
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• pp.931-953
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• 2016

In this paper, the effects of mass eccentricity of superstructure as well as stiffness eccentricity of isolators on the amplification of seismic responses of base-isolated structures are investigated by using mathematical near-fault pulse models. Superstructures with 3, 6 and 9 stories and aspect ratios equal to 1, 2 and 3 are mounted on a reasonable variety of Triple Concave Friction Pendulum (TCFP) bearings considering different period and damping ratio. Three-dimensional linear superstructure mounted on nonlinear isolators are subjected to simplified pulses including fling step and forward directivity while various pulse period ($T_p$) and Peak Ground Velocity (PGV) amounts as two crucial parameters of these pulses are scrutinized. Maximum isolator displacement and base shear as well as peak superstructure acceleration and drift are selected as the main engineering demand parameters. The results indicate that the torsional intensification of different demand parameters caused by superstructure mass eccentricity is more significant than isolator stiffness eccentricity. The torsion due to mass eccentricity has intensified the base shear of asymmetric 6-story model 2.55 times comparing to symmetric one. In similar circumstances, the isolator displacement and roof acceleration are increased 49 and 116 percent respectively in the presence of mass eccentricity. Furthermore, it is demonstrated that torsional effects of mass eccentricity can force the drift to reach the allowable limit of ASCE 7 standard in the presence of forward directivity pulses.

• Earthquakes and Structures
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• v.6 no.5
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• pp.473-494
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• 2014

Progressive collapse, which is referred to as the collapse of the entire building under local damages, is a common failure mode happened by earthquakes. The collapse process highly depends on the whole structural system. Since, asymmetry of the building plan leads to the local damage concentration; it may intensify the progressive collapse mechanism of asymmetric buildings. In this research the progressive collapse of regular and irregular 6-story RC ordinary moment resisting frame buildings are studied in the presence of the earthquake loads. Collapse process and collapse propagation are investigated using nonlinear time history analyses (NLTHA) in buildings with 5%, 15% and 25% mass asymmetry with respect to the number of collapsed hinges and story drifts criteria. Results show that increasing the value of mass eccentricity makes the asymmetric buildings become unstable earlier and in the early stages with lower number of the collapsed hinges. So, with increasing the mass eccentricity in building, instability and collapse of the entire building occurs earlier, with lower potential of the progressive collapse. It is also demonstrated that with increasing the mass asymmetry the decreasing trend of the number of collapsed beam and column hinges is approximately similar to the decreasing trend in the average story drifts of the mass centers and stiff edges. So, as an alternative to a much difficult-to-calculate local response parameter of the number of collapsed hinges, the story drift, as a global response parameter, measures the potential of progressive collapse more easily.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.4
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• pp.140-144
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• 2015

Effects of the shape, the size and the material of head mass on performances of tonpilz transducer were studied with a finite element method. The shape of head mass was changed with an angle between symmetric axis and side of head mass of transducer from 0 to 60 degree. As a result of the simulations, the bandwidth leached to 86.4 % at 35.5 degree in case of Al head mass. The size of head mass showed a decrease in the power of transducer with little change of bandwidth. For the Ti head mass, the transmitted power showed 100 % increase with a bandwidth of 88.1 % even though the weight of the head mass increased to 167 % of Al. This can be attributed to the mechanical properties like elastic modulus of Ti relative to Al.