• Journal of Korean Foot and Ankle Society
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• v.27 no.2
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• pp.75-78
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• 2023

During bone tumor resection, many cases require medial malleolar osteotomy to achieve adequate access to the operative field. Various osteotomy methods have been developed to address this issue, including oblique, transverse, reverse V-shape, and step-cut osteotomies. However, medial malleolar osteotomy has several drawbacks, such as the excessive disruption of the joint surface, unstable screw fixation when fixing the medial malleolus, and iatrogenic medial ankle joint arthritis due to articular displacement during the reduction of the osteotomy site. In addition, there is a possibility of injury to the posterior tibial artery, tibial nerve, or posterior tibialis tendon if the osteotomy range is too aggressive. Therefore, the authors propose a new osteotomy method, which has shown promising clinical results, namely, partial posterior medial malleolar osteotomy. This method minimizes articular involvement and provides adequate access to the operative field during talar body bone tumor resection.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.55.2-55.2
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• 2019

The firehose instability is driven by a pressure anisotropy in a magnetized plasma when the temperature along the magnetic field is higher than the perpendicular temperature. Such condition occurs commonly in astrophysical and space environments, for instance, when there are beams aligned with the background magnetic field. Recently, it was argued that, in weak quasi-perpendicular shocks in the high-β intracluster medium (ICM), shock-reflected electrons propagating upstream cause the temperature anisotropy. This electron temperature anisotropy can trigger the electron firehose instability (EFI), which excites oblique waves in the shock foot. Scattering of electrons by these waves enables multiple cycles of shock drift acceleration (SDA) in the preshock region, leading to the electron injection to diffusive shock acceleration (DSA). In the study, the kinetic properties of the EFI are examined by the linear stability analysis based on the kinetic Vlasov-Maxwell theory and then further investigated by 2D Particle-in-Cell (PIC) simulations, especially focusing on those in high-β (β~100) plasmas. We then discuss the basic properties of the firehose instability, and the implication of our work on electron acceleration in ICM shock.

• Ocean Systems Engineering
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• v.13 no.2
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• pp.147-172
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• 2023

This study investigates the influence of loading and inflow conditions on tidal turbine performance from a hydrodynamic and hydroacoustic point of view. A boundary element method is utilized for the former to investigate turbine performance at various loading conditions under zero/non-zero yaw inflow. The boundary element method is selected as it has been selected, tested, and validated to be computationally efficient and accurate for marine hydrodynamic problems. Once the hydrodynamic solutions are obtained, such as the time-dependent surface pressures and periodic motion of the turbine blade, they are taken as the known noise sources for the subsequence hydroacoustic analysis based on the Ffowcs Williams-Hawkings formulation given in a form proposed by Farassat. This formulation is coupled with the boundary element method to fully consider the three-dimensional shape of the turbine and the speed of sound in the acoustic analysis. For validations, a model turbine is taken from a reference paper, and the comparison between numerical predictions and experimental data reveals satisfactory agreement in hydrodynamic performance. Importantly, this study shows that the noise patterns and sound pressure levels at both the near- and far-field are affected by different loading conditions and sensitive to the inclination imposed in the incoming flow.

• Journal of Ocean Engineering and Technology
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• v.37 no.2
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• pp.68-79
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• 2023

Even though submerged breakwater reduces incident wave energy, it redistributes the coastal area's wave-induced current, sediment transport, and morphological change. This study examines the coastal hydrodynamics and the morphological response of a wave-dominated beach with submerged breakwaters installed through field observation and quasi-3D numerical modeling. The pre-and post-storm bathymetry, water level, and offshore wave under storm forcing were collected in Bongpo Beach on the East coast of Korea and used to analyze the coastal hydrodynamic response. Four vertically equidistant layers were used in the numerical simulation, and the wave-induced current was examined using quasi-3D numerical modeling. The shore normal incident wave (east-northeast) generated strong cross-shore and longshore currents toward the hinterland of the submerged breakwater. However, the oblique incident wave (east-southeast) induced the southeastward longshore current and the sedimentation in the northeast area of the beach. The results suggested that the incident wave direction is a significant factor in determining the current and sediment transport patterns in the presence of the submerged breakwaters. Moreover, the quasi-3D numerical modeling is more appropriate for estimating the wave transformation, current, and sediment transport pattern in the coastal area with the submerged breakwater.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.228.1-228.1
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• 2015

We demonstrate a simple route to hybridize two different nanomaterials by using three-dimensional nanodishes that can be used as small plasmonic containers to host guest nanoparticles. Our nanodishes were fabricated using nanoimprint lithography and oblique-angle film deposition, and the guest nanoparticles were drop-casted onto the host nanodishes. Based on the proposed method, colloidal Au nanoparticles were assembled inside Au nanodishes in the form of a labyrinth. These Au nanoparticle-nanodish hybrids excited a strong surface plasmon resonance, as verified by a numerical simulation of the local field enhancement and by direct observation of the enhanced Raman signals. Our results point to the potential of the nanodishes as a useful platform for combining diverse nanomaterials and their functionalities.

• Journal of KSNVE
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• v.4 no.3
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• pp.295-305
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• 1994

The reflection coefficient of a material at oblique incidence is measured in a free field. The sound pressure distributions are measured at discrete points on two measurement lines and then decomposed into plane wave components by using spatial Fourier transform. The inciedent and reflected plane wave components are obtained from a set of "decomposition equations" of which uses the plane wave propagation theory. Numerical simulations and experiments have been performed to see the effect of finite size of measurement area. To reduce this effect, a window fuction has been performed to see the effects of finite size of mesurement area. To reduce this effect, a window function has been proposed and its effect on the measurement of sound absorbing material property has been studied as well. The reflection coefficient obtained by this method is compared with those obtained from other methods; 2-microphone method in a duct and an expirical equation of which determines the characteristic impedance .rho.c and propagation constant k of a material from flow resistance information.formation.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.295-297
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• 2003

The coastal provinces of South China have been uniquely shaped by various tectonic events. During the midlate Mesozoic tectono-thermal event, the oblique subduction of the Paleo Kula-Pacific plate beneath the Eurasian plate has created a complicated tectonic setting for the whole region. However, the mechanism of this event is not completely understood. In this paper, we discuss the advantages of using LANDSAT TM satellite imagery over a small part of the region - the Mirs Bay Basin which is largely covered by dense vegetation and where limited outcrops is seen. The use of satellite imagery complements field mapping and the result shows a prominent sinistral offset along the eastern margin of the Mirs Bay Basin, which was not previously recognized on the ground.

• ALGAE
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• v.22 no.3
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• pp.159-165
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• 2007

Morphological and anatomical characters of Amphiroa rigida Lamouroux were investigated with field materials and taxonomic accounts are given to the species. The species grows in the subtidal zone of Cheju island, and is characterized by semiendophytic habit in Hydrolithon onkodes. The species is well defined by about 1 cm height, loosely tufted thallus with irregular branches, two-tiered geniculum with equal length, geniculum tier connecting by oblique end walls, and conceptacles buried in cortices of intergeniculum. Korean isolates have etrasporangial, male and female conceptacles. The structure and developmental patterns of conceptacles are very similar to those shown in previous studies.

• Journal of Mechanical Science and Technology
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• v.17 no.2
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• pp.269-279
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• 2003

The anti-plane shear problem of bonded elastic materials containing a crack at an arbitrary angle to the graded interfacial zone is investigated in this paper The interfacial zone is modeled as a nonhomogeneous interlayer of finite thickness with the continuously varying shear modulus between the two dissimilar, homogeneous half-planes. Formulation of the crack problem is based upon the use of the Fourier integral transform method and the coordinate transformations of basic field variables. The resulting Cauchy-type singular integral equation is solved numerically to provide the values of mode 111 stress intensity factors. A comprehensive parametric study is then presented of the influence of crack obliquity on the stress intensity factors for different crack size and locations and for different material combinations, in conjunction with the material nonhomogeneity within the graded interfacial zone.

• International journal of advanced smart convergence
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• v.1 no.2
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• pp.43-46
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• 2012

We analyzed a periodic thick mushroom structure for use as an artificial magnetic conductor using mode-matching method. The fields in each region were represented by either Floquet modes or waveguide modes. By applying tangential electric and magnetic field continuity conditions and using matrix equations, unknown coefficients and dispersion diagram were calculated. The proposed model can account for the effects of oblique incidence. Simulation time using the method was much faster than the commercial tools. We found that the current method produces accurate results of reflection phase and dispersion diagram.