• Journal of Korean Neurosurgical Society
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• v.41 no.3
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• pp.177-179
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• 2007

Most of intradural epidermoid cyst arise as slowly growing extraaxial lesions but purely intracerebral epidermoid cysts are rare. A 39-year-old female presented with a headache during several months. Brain computed tomography [CT] scan showed a mass lesion in the both frontal lobe with heterogenous density approximately $5{\times}5cm$ in size. Magnetic resonance imaging [MRI] revealed a mass of heterogenous signal intensity on T1, T2-weighted image and faint enhancement with gadolinium [Gd]. Through the both interhemispheric approach, mass was removed subtotally except the calcified portion tightly attached to the corpus callosum. The patient discharged without neurological deficit. The authors report a case of epidermoid cyst in the corpus callosum and discuss the pathogenesis of the intraparenchymal epidermoid cyst.

• Nuclear Engineering and Technology
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• v.32 no.1
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• pp.17-33
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• 2000

A mechanistic model based on wall-attached bubble coalescence, previously developed by the authors, was extended to predict a vow high critical heat flux (CHF）in highly subcooled flow boiling, especially for high mass flux and small tube diameter conditions. In order to take into account the enhanced condensation due to high subcooling and high mass velocity in small diameter tubes, a mechanistic approach was adopted to evaluate the non-equilibrium flow quality and void fraction in the subcooled water flow boiling, with preserving the structure of the previous CHF model. Comparison of the model predictions against highly subcooled water CHF data showed relatively good agreement over a wide range of parameters. The significance of the proposed CHF model lies in its generality in applying over the entire subcooled flow boiling regime including the operating conditions of fission and fusion reactors.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1429-1434
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• 2013

A synthesis and cation-induced fluorescent behavior of the carbazole-attached $NO_2S_2$-macrocycle (L) is described and structurally characterized by single crystal X-ray analysis. The photoluminescence spectrum of L in 80% $CH_3CN/CH_2Cl_2$ displays a peak maximum at 431 nm (blue emission). In the metal-induced fluorometric experiment, L showed a drastic chelation-enhanced fluorescence quenching (CHEQ) effect only with $Hg^{2+}$ and $Cu^{2+}$. In ESI-mass study, a 1:1 stoichiometry for complexation of L with $Hg^{2+}$ was confirmed, suggesting the unique sensing behavior of the proposed ligand L due to the selective complexation affinity for $Hg^{2+}$. The observed results indicate that L is a promising turn-off type fluoroionophore for $Hg^{2+}$ and $Cu^{2+}$ detections. Additionally, the $Ag^+$ complex of the precursor macrocycle was prepared and its solid structure was crystallographically characterized.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.77.2-77.2
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• 2010

We report a possible low-mass companion around the K2 III star $\varepsilon$ CrB (HD 143107). This star belongs to our sample of 55 K-giants studied for their radial velocity variations using the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) attached to the 1.8-m telescope at Bohyunsan Optical Astronomy Observatory (BOAO). Our precise radial velocity measurements were obtained from February 2005 to June 2010. We find an orbital solution with a period of P = 419 days, a semi-amplitude of K = 137 m/s, and an eccentricity of e = 0.14. Assuming a moderate stellar mass of $M_{\bigstar}=0.77\;M\odot$, we calculate the minimum mass for the companion of m sini = $4.2\;M_{Jup}$ with an orbital semi-major axis of 1.0 AU.

• Structural Engineering and Mechanics
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• v.83 no.1
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• pp.31-43
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• 2022

A nonlinear gas-spring tuned mass damper is proposed to mitigate the seismic responses of the multi-degree-of-freedom (MDOF) structure, in which the nine-story benchmark model is selected as the controlled object. The nonlinear mechanical properties of the gas-spring are investigated through theoretical analysis and experiments, and the damper's control parameters are designed. The control performance and damping mechanism of the proposed damper attached to the MDOF structure are systematically studied, and its reliability is also explored by parameter sensitivity analysis. The results illustrate that the nonlinear gas-spring TMD can transfer the primary structure's vibration energy from the lower to the higher modes, and consume energy through its own relative movement. The proposed damper has excellent "Reconciling Control Performance", which not only has a comparable control effect as the linear TMD, but also has certain advantages in working stroke. Furthermore, the control parameters of the gas-spring TMD can be determined according to the external excitation amplitude and the gas-spring's initial volume.

• Ocean Systems Engineering
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• v.9 no.4
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• pp.369-390
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• 2019

Herein, we present numerical simulation based model to study the use of a 'Tuned Mass Damper (TMD)' - particularly spring mass systems - to control the displacements at the deck level under seismic and ice loads for an offshore jacket structure. Jacket is a fixed structure and seismic loads can cause it to vibrate in the horizontal directions. These motions can disintegrate the structure and lead to potential failures causing extensive damage including environmental hazards and risking the lives of workers on the jacket. Hence, it is important to control the motion of jacket because of earthquake and ice loads. We analyze an offshore jacket platform with a tuned mass damper under the earthquake and ice loads and explore different locations to place the TMD. Through, selected parametric variations a suitable location for the placement of TMD for the jacket structure is arrived and this implies the design applicability of the present research. The ANSYS^*TM mechanical APDL software has been used for the numerical modeling and analysis of the jacket structure. The dynamic response is obtained under dynamic seismic and ice loadings, and the model is attached with a TMD. Parameters of the TMD are studied based on the 'Principle of Absorption (PoA)' to reduce the displacement of the deck level in the jacket structure. Finally, in our results, the proper mass ratio and damping ratios are obtained for various earthquake and ice loads.

• Structural Engineering and Mechanics
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• v.53 no.6
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• pp.1105-1126
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• 2015

Many vibrating mechanical systems from the real life are modeled as combined dynamical systems consisting of beams to which spring-mass secondary systems are attached. In most of the publications on this topic, masses of the helical springs are neglected. In a paper (Cha et al. 2008) published recently, the eigencharacteristics of an arbitrary supported Bernoulli-Euler beam with multiple in-span helical spring-mass systems were determined via the solution of the established eigenvalue problem, where the springs were modeled as axially vibrating rods. In the present article, the authors used the assumed modes method in the usual sense and obtained the equations of motion from Lagrange Equations and arrived at a generalized eigenvalue problem after applying a Galerkin procedure. The aim of the present paper is simply to show that one can arrive at the corresponding generalized eigenvalue problem by following a quite different way, namely, by using the so-called "characteristic force" method. Further, parametric investigations are carried out for two representative types of supporting conditions of the bending beam.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.9
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• pp.1249-1259
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• 2002

The present study investigates the convective heat/mass transfer inside a cooling passage of rotating gas-turbine blades. The rotating duct has various configurations made of ribs with 70。 attack angle, which are attached on leading and trailing surfaces. A naphthalene sublimation technique is employed to determine detailed local heat transfer coefficients using the heat and mass transfer analogy. The present experiments employ two-surface heating conditions in the rotating duct because the surfaces, exposed to hot gas stream, are pressure and suction side surfaces in the middle passages of an actual gas-turbine blade. In the stationary conditions, the parallel rib arrangement presents higher heat/mass transfer characteristics in the first pass, however, these characteristics disappear in the second pass due to the turning effects. In the rotating conditions, the cross rib present less heat/mass transfer discrepancy between the leading and the trailing surfaces in the first pass. In the second pass, the heat/mass transfer characteristics are much more complex due to the combined effects of the angled ribs, the sharp fuming and the rotation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.8 s.227
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• pp.921-928
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• 2004

Measurements of local heat/mass transfer coefficients in rotating two-pass ducts are presented. Ducts of three different aspect ratios (W/H), 0.5, 1.0 and 2.0, are employed with a fixed hydraulic diameter ($D_h$) of 26.7 nm. $90^{\circ}$-rib turbulators are attached on the leading and trailing walls symmetrically. The rib height-to-hydraulic diameter ratio ($e/D_h$) is 0.056, and the rib pitch-to-rib height ratio (p/e) is 10. The experimental conditions are the same as those of the previous part of the study. As the rib height-to-duct height ratio (e/H) increases, the core flow is more disturbed and accelerated in the midsections of ribs. Therefore, the obtained data show higher heat/mass transfer in the higher aspect ratio duct. Dean vortices also augment heat/mass transfer in the turn and in the upstream region of the second pass. However, the effect becomes less significant for the higher aspect ratio because the surface area increases in the present geometric condition. The effect of rotation produces heat/mass transfer discrepancy.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.447-447
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• 2011

We studied to detect the mass variation using micro mechanical resonator. For measuring the resonance frequency of the micro mechanical system, optical method using laser interference is selected. A simple resonator is prepared by attaching an AFM cantilever on the piezo stack. The piezo stack makes a the cantilever vibrated with its resonance frequency. To change the mass of the resonator, gold was evaporated on the cantilever. We measured how much resonance frequency was changed according to the amount of gold attached on cantilever. This resonator is able to perform the role of a mass sensor and has a resolution of the order of micrograms. The fabrication of the resonator and measurement setup for detecting the mechanical resonance will be introduced in this presentation.