• Journal of Magnetics
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• v.19 no.3
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• pp.261-265
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• 2014

Three-dimensional computed tomography is an effective tool to estimate the liver volume of living donors for the live liver transplantation. When additional operation is required, magnetic resonance imaging is conducted to determine the safety of the donor. This study compared the accuracy of magnetic resonance imaging and computed tomography in estimating 3D liver volume of 23 male and 7 female donors who underwent both magnetic resonance imaging and computed tomography tests before the transplantation. The analysis was conducted to see whether the liver's estimated total volumes and the left lobe volumes obtained from 3D-magnetic resonance imaging and 3D-computed tomography were identical. Volumes of the right lobe estimated with 3D-magnetic resonance imaging and 3D-computed tomography were compared with the actual volume of the right lobe harvested in the operating room because the volume of the right lobe is an important determinant in the safety of the donor. The total volume of the liver estimated from 3D-magnetic resonance imaging and 3D-computed tomography differed (1238.1904 units and 1402.364 units respectively). The left lobe volume of the liver estimated with 3D-magnetic resonance imaging and 3D-computed tomography also differed (450.530 units and 554.490 units, respectively). The right lobe volume of the liver estimated with 3D-magnetic resonance imaging and 3D-computed tomography were 787.660 units and 847.545 units, respectively, while the actual average right lobe volume of the harvested liver was 678.636 units. 3D-computed tomography has been widely used to estimate the right lobe volume of the donors' liver. However, 3D-magnetic resonance imaging was also very effective in estimating the volume of the liver. Thus, 3D-magnetic resonance imaging is also expected to become an important tool in determining the safety of the donors before transplantation.

• Journal of the Korean Magnetic Resonance Society
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• v.7 no.1
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• pp.46-54
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• 2003

We synthesized a contrast agent for MRI that is capable of binding to the ABP-1 receptor and enhancing the contrast of the targeted cells. We used a lysine dendrimer (G=3)DTPA[Gd] as the contrast agent and synthesized a biotinylated polyclonal antibody for ABP-1 as the first antibody. Lysine dendrimers were prepared using the solid phase peptide synthesis method.$^3$ Amino-terminated lysine dendrimers were then coupled to DTPA using the anhydride method. Gd was complexed with the DTPA-lysine dendrimer in an acidic solution of 3 eq GdCl$_3$ to one of DTPA. The lysine dendrimer-DTPA[Gd] and avidin were conjugated in MES solution, pH 6.0, using EDC as the coupling reagent. The biotin-avidin system was used to link the polyclonal antibody and contrast agent. K562 cells were used for imaging.

• Korea-Australia Rheology Journal
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• v.11 no.4
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• pp.279-285
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• 1999

Draw resonance is both an important and interesting instability encountered in various extensional-deformation-dominated polymer processing operations. It is important because of its paramount relevance to the productivity and quality issue in the related industry: and it is interesting because of as yet unanswered questions as to what its cause and origin are in terms of physics involved. Specifically, a short chronological account of the draw resonance research is presented in this paper bringing several previous results together and focusing on the derivation of a new criterion for draw resonance based on the interaction of the traveling times of some kinematic waves propagating along the spinline from the die exit to the take-up position. The new explanation of draw resonance put forward here based on the physics of the system is seen to have wide implications on both theoretical and practical aspects of draw resonance instability. The importance of the role played by spinline tension in determining draw resonance is an example of the former whereas interpretation of the mechanism of the draw resonance eliminator is an example of the latter. Finally, an approximate yet a very fast and convenient method for determining draw resonance is also derived based on the above findings and found to agree well with the exact stability results.

• Progress in Superconductivity and Cryogenics
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• v.17 no.1
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• pp.36-39
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• 2015

Many studies are being conducted to implement wireless charging, for example, for cellular phones or electronic tooth brushes, via wireless power transmission technique. However, the magnetic induction method had a very short transmission distance. To solve this problem, the team of Professor Marin Soljacic proposed a magnetic resonance system that used two resonance coils with the same resonance frequency. It had an approximately 40% efficiency at a 2m distance. The system improved the low efficiency and short distance problems of the existing systems. So it could also widen the application range of wireless power transmission. Many studies on the subject are underway. In this paper, the superconductor coil was used to improve the efficiency of magnetic resonance wireless power transmission. The resonance wireless power transmission system had a source coil, a load coil, and resonance coils (a transmitter and a receiver). The efficiency and distance depended on the characteristics of the transmitter and receiver coils that had the same resonance frequency. Therefore, two resonance coils were fabricated by superconductors. The current density of the superconductor was higher than that of the normal conductor coil. Accordingly, it had a high quality-factor and improved efficiency.

• Korean Journal of Materials Research
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• v.21 no.7
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• pp.403-409
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• 2011

Micro speakers are used to reproduce sound in small electric and information and communications devices, such as cellular phones, PMPs, and MP3 players. The acoustical properties and sound quality, which are changed due to the decreased size of the speaker, are often adjusted varying the type and thickness of the diaphragm. The most widely used diaphragm material is thin polymer. It was previously reported by the author of this paper that the resonance frequency of a micro speaker is changed by the type and thickness of a polymer diaphragm. In this paper, the frequency response near the resonance frequency of a micro speaker was studied as functions of the type and thickness of the polymer diaphragm. While $R_{max}$ and $R_{DC}$ were affected by the type and thickness, an analysis of the electrical impedance curve revealed that $R_o(= R_{max}/R_{DC})$ and ${\Delta}f$ were not changed. Thus, $Q_{TS}$ which was function of $R_o$, ${\Delta}f$, and the resonance frequency, is only related to the resonance frequency. The increase of the resonance frequency led to a proportional rise of $Q_{TS}$. The change of the frequency response near the resonance frequency was not dependent on the type or thickness of the polymer diaphragm, but was affected by the resonance frequency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.150-155
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• 2000

This paper presents phenomena of vibration and noise due to acoustic resonance in tube bank of a power plant. Acoustic resonance is may arise when the vortex shedding frequency coincides with the acoustic natural frequency. At the resonance, the value of vibration in this system was 595 ${\mu}m$, p-p and the sound pressure level was maximum 103 dBA. And the resonance frequency was found to be 35 Hz. When the difference of vortex shedding frequency and acoustic natural frequency is within ${\pm}20%$, acoustic resonance is possible. In this system, the difference of these frequencies was 1.8%. We can evaluate the possibility of acoustic resonance by using damping parameter. We did eliminate acoustic resonance by installing baffle in tube bank. After installing baffle, the level of vibration and noise was reduced dramatically.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.151-160
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• 2008

In this paper, the analysis results of synthetic resonance characteristics are described for the electrohydraulic thrust vector control actuation system. The synthetic resonance is induced by integration of position servo actuation system on the flexible launch vehicle mounting structure. The new resonance mode is synthesized due to composition of hydraulic resonance for electrohydraulic position servo system with inertia load condition and structural resonance for flexible mounting structure. This synthetic resonance can make stability of control system worse by feedback and amplification of control system. The exact nonlinear analysis model of this phenomenon is developed to predict and design a control algorithm for improvement characteristics. The DPF (Dynamic Pressure Feedback) control algorithm has been designed and has excellent resonance suppression capability.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.309-313
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• 2009

A micromechanical resonance sensor detects the resonance frequency shift due to mass or adsorption induced surface stress change during molecular adsorption or interaction on its surface. The resonance sensor is surrounded by gas or liquid solution during operation. To study the resonance shift phenomena depending on its surrounding environment, fluid-structure interaction of the resonance sensor has been analyzed for the different fluid environment and boundary conditions using finite element analysis.

• Progress in Superconductivity and Cryogenics
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• v.20 no.1
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• pp.23-27
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• 2018

As the wireless power transfer (WPT) technology based on strongly resonance coupled method realizes large power charging without any wires through the air, there are advantages compared with the wired counterparts, such as convenient, safety and fearless transmission of power. From this reason, the WPT systems have started to be applied to the wireless charging for various power applications such as train, underwater ship, electric vehicle. This study aims for the effect and characteristics of different inserted resonance coil between Tx and Rx coils for charging system of superconducting magnetic levitation (MAGLEV) train. The transfer efficiency and effect are evaluated with helix type, rectangular type copper resonance coil, and HTS resonance coil under bulb and HTS magnet load, respectively. The input power is adapted with radio frequency (RF) power of 370 kHz below 500 W.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.890-895
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• 2001

Pressure resonance frequency that is caused in the combustion chamber can be interpreted to acoustic analysis. Until now the pressure resonance has been assumed and calculated to a disc type combustion chamber that neglected the combustion chamber height because the knock occurs near the TDC(top dead center). In this research FEM(fine element method) has been used to calculate the pressure resonance frequency inside the experimental engine combustion. The reduce error of the resonance frequency obtained by FEM has decreased about 50% compared to the calculation of Draper's equation. Due to the asymmetry in the shape of the combustion chamber that was neglected in Draper's equation we could find out that a new resonance frequency could be generated. To make the experimental results equal we could know that the speed of sound that satisfies Draper's equation was selected 13% higher than all the pent-roof type combustion considered.