• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.234-235
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• 2005

This paper present a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. The piezoelectric transformers operated in each transformer's resonance vibration mode. The electrodes and poling directions on commercially available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor ($k_p,\;k_{15}$) becomes effective rather than the transverse mode coupling factor ($k_{31}$).

• Archives of Plastic Surgery
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• v.43 no.4
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• pp.371-373
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• 2016

Venous malformations arising from the peripheral nerve are a rare type of vascular malformation. We present the first case of an intraneural venous malformation of the median nerve to be reported in a child and review the previous two cases of median nerve compression due to a venous malformation that have been reported. These cases presented with painless masses in the volar aspect of the wrist or with symptoms suggestive of carpal tunnel syndrome. Clinical suspicion should lead to the use of Doppler ultrasonography as the first-line diagnostic tool. Magnetic resonance imaging and histopathology can confirm the diagnosis, as phleboliths are pathognomonic of venous malformations. Surgical treatment appears to be the only modality capable of successfully controlling the growth of an intraneural malformation. Sclerotherapy and radiotherapy have never been used to treat this type of malformation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.151-152
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• 2006

Nowadays, great attention has been shown to the question of ultrasonic linear motor for accomplishing the high positioning accuracy and high driving force in the semiconductor and optical industry. Ultrasonic linear motors have many advantages such as simple structure, quick response, ability to maintain position without energy consumption, and electromagnetic effect. And BLT has attracted attention to accomplish large vibration amplitude and large mechanical force. Authors designed and developed the new type of ultra sonic linear motor with multi support mechanism, achieved 75N of output force and 0.45m/s of velocity.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.303-303
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• 2011

Orderings and electronic structures of organic molecules on metal substrates have been studied due to possible applications in electronic devices. In molecular systems, delocalized pi-electrons play important roles in the adsorption behaviors and electronic structures. We studied the adsorption and electronic structures of Co-Porphyrin molecules on Au(111) using scanning tunneling microscopy (STM) and spectroscopy (STS) at low temperature. Molecules form closely packed two-dimensional islands on Au(111) surface with two different types, having different shape evolutions in our energy-dependent STM observations. The Kondo resonance state, occurred by spin exchange interaction between the Co center atom and conduction electrons in the metal substrate, was observed in one type, while it was absent in the other type in scanning tunneling spectroscopy measurements. Possible origins of two molecular shapes will be discussed.

• Journal of Magnetics
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• v.18 no.2
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• pp.163-167
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• 2013

We fabricated prototype cantilevers for mechanically detected high-frequency ESR measurement. Cantilevers are fabricated from silicon-on-insulator (SOI) wafers using standard MEMS techniques such as lithography, wet etching, and plasma etching. Using commercial SOI wafers, fabrication cost and the number of processes can be substantially reduced. In this study, three types of cantilevers, designed for capacitive and optical detection, are shown. Capacitive type with lateral dimensions of $3.5{\times}1.6mm^2$ is aimed for low spin concentration sample. On the other hand, optical detection type with lateral dimensions of $50{\times}200{\mu}m^2$ is developed for high-sensitive detection of tiny samples such as newly synthesized microcrystals.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3216-3218
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• 2000

Projection-type Fast Spin Echo (PFSE) imaging has robustness against motion artifacts due to patient motion during magnetic resonance imaging data acquisition, or reduce flow artifacts. However, it has difficulty in controlling T2 contrast. In this paper, T2 contrast in the PFSE method is analyzed. The contrasts in FSE and PFSE method are compared by computer simulation and experiments with volunteers.

• Smart Structures and Systems
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• v.20 no.5
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• pp.583-593
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• 2017

This research deals with the nonlocal temperature-dependent dynamic buckling analysis of embedded sandwich micro plates reinforced by functionally graded carbon nanotubes (FG-CNTs). The material properties of structure are assumed viscoelastic based on Kelvin-Voigt model. The effective material properties of structure are considered based on mixture rule. The elastic medium is simulated by orthotropic visco-Pasternak medium. The motion equations are derived applying Sinusoidal shear deformation theory (SSDT) in which the size effects are considered using Eringen's nonlocal theory. The differential quadrature (DQ) method in conjunction with the Bolotin's methods is applied for calculating resonance frequency and dynamic instability region (DIR) of structure. The effects of different parameters such as volume percent of CNTs, distribution type of CNTs, temperature, nonlocal parameter and structural damping on the dynamic instability of visco-system are shown. The results are compared with other published works in the literature. Results indicate that the CNTs have an important role in dynamic stability of structure and FGX distribution type is the better choice.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.2
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• pp.126-130
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• 2009

The present study describes an investigation into the characteristics of combustion oscillation and its suppression instability of a silo type gas turbine combustor in commercial power plant. Combustion oscillation is occurred the combustor in near full load during operation. As a result of FFT analysis of the combustion dynamics, the frequency of the oscillation is analyzed as the 1'st longitudinal mode of acoustic resonance of the combustor. For suppress of the instability, combustion tuning with adjust of fuel valve schedule is carried out, which changes equivalent ratio of each burners. As the result, the oscillation is successfully reduced with meeting the level of NOx emission regulation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.1
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• pp.40-47
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• 2000

This paper presents a circuit of resonant voltage resultant type DC/DC converter consists of two unit half-bridge high frequency resonant inverters, and describes operating modes, principle and analysis of the proposed circuit. Also, the analysis of the proposed circuit has generally described by using normalized parameters. Based on the characteristic values, a method of the circuit design is proposed. According to phase shift, the output voltage of the proposed circuit can be controlled. In addition, the justification of theoretical analysis was certified by comparing to the experimental waveforms. In the future, this proposed converter show that it can be practically used as the system of fixed DC voltage source etc.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.4
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• pp.261-266
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• 1998

In developing the high density memory device, the etching of fine pattern is becoming increasingly important. Therefore, definition of ultra fine line and space pattern and minimization of damage and contamination are essential process. Also, the high density plasma in low operating pressure is necessary. The candidates of high density plasma sources are electron cyclotron resonance plasma, helicon wave plasma, helical resonator, and inductively coupled plasma. In this study, planar type magnetized inductively coupled plasma etcher has been built. The density and temperature of Ar plasma are measured as a function of rf power, flow rate, external magnetic field, and pressure. The oxide etch rate and selectivity to polysilicon are measured as the above mentioned conditions and self-bias voltage.