• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.161-164
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• 1996

An actively-shielded $r^{2}$-gradient coil has been developed for brain localized MRI or MRS. Spatial localization is very useful for spatial volume selection in MRI or MR Spectroscopy(MRS). The radial(or $R^{2}-$) gradient coil is useful in reducing the artifact or in improving the SNR by selecting the volume with less number of RF pulses. It is, however, difficult to implement the coil with a gradient intensity strong enough to use it for practical whole-body MRI system. For example, the smallest volume size for selection is just 6 cm in diameter with a 250 Ampere of current driving for a whole-body system (in case of 70-cm-diameter). In this study, an asymetric $r^{2}$-coil with a small diameter of 35 cm has been designed and implemented for brain localized MRI or MRS. An 8-rod high-pass-type birdcage RF coil has also been implemented. The coil set has been developed for 1.0 Tesla Medison MRI system and its performance has been verified experimentally.

• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.1
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• pp.29-33
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• 1996

The eddy current test(ECT) probe of differential encircling coil type was designed and fabricated, and the optimum condition of ECT was derived for the examination of the irradiated fuel rod. The correlation between ECT test frequency and phase & amplitude was derived by performing the test of the standard rig that includes inner notches, outer notches and through-holes. The defect of through-hole was predicted by ECT at the G33-N2 fuel rod irradiated in the Kori-1 nuclear power reactor. The metallographic examination on the G33-N2 fuel rod was Performed at the defect location predicted by ECT. The result of metallographic examination for the G33-N2 fuel rod was in good agreement with that of ECT. This proves that the evaluation for integrity of irradiated fuel rod by ECT is reliable.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.638-640
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• 2002

This paper introduces the design method of a Control Rod Drive Mechanism that consists of 3 coils -lift, movable gripper and stationary gripper coil. The vertical attraction forces of the lift, movable gripper, and stationary gripper armatures are calculated by FEM, then the dynamics with full load is demonstrated.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.1
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• pp.29-33
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• 1992

A non-contact torque sensor was developed using amorphous alloy. The change of maixmum magnetic induction of C0-based amorphous alloy under the tensile and compressive stress was proportional to applied torque. For the construction of the torque sensor, a glass fiber reinforced-epoxy rod was used as shaft. The amorphous strips were attached on the epoxy shaft in the direction of $+45^{\circ}$and $-45^{\circ}$. The magnetizing coil and 2 sensing coil was installed. The static and dynamic test was carried out. The linearity and sensor hysteresis of the torque sensor was less than 1%.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.74-75
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• 2006

In organic opto-electronic applications, such as light emitting diodes (LEDs) and photovoltaic devices (PVDs), the morphology of the active layer is of crucial importance. To control the morphology of the active layer the self-assembling properties of block copolymers was used. Several rod-coil semiconducting diblock copolymers consisting of a conjugated block and a second coil block functionalized with electron transporting and/or accepting materials (such as $C_{60}$) were synthesized. The conjugated block acting as light absorbing, electron donating and hole transporting material. The donor/acceptor photovoltaic devices performance with active layer the above mentioned semiconducting block copolymers will be presented.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2301-2303
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• 2004

This paper proposes a detection method for mechanically stuck control rod drive mechanisms (CRDMs) in the nuclear reactor. From an electrical viewpoint, a coil of an electro-mechanical CRDM is modelled as an R-L circuit with time-varying inductance. The inductance of the coil is estimated from the measured voltage and current by using the least square method. Numerical experiments are carried out to illustrate the proposed method.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.221-223
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• 1990

In this study, we have studied the optioal properties and $I_2$ doping effect of Poly(3-Akkylthiophene) solution. The end of speotrum absorbance on the solutions of Poly(3 - Octylthiophene), Poly (3-Dodecylthiophene) and Poly(3-Dooooylthiophene) was dependent on temperature. It is bellved that conrod-coil transition dependent on temperature was rod-coil transition. And absortance peak of Poly (3-Dodecylthiophene) in dichloromethane solution increased with increasing the $I_2$ dopant.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2066-2068
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• 2001

In this study, we have developed the automatic voltage regulator(AVR) with robust voltage controllability, high efficiency and low cost. In AVR, the output voltage is controlled by the Tap changing of the slidacs coil using DC motor. And AVR has the improved output voltage characteristics because of the modified configuration of a point of contact between the slidacs coil and the moving rod.

• Journal of Magnetics
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• v.4 no.3
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• pp.98-101
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• 1999

In this work we htave constructed an under water sonar transducer using Terfenol-D rod employing open magnetic circuit. Normally Sonar transducer using Terfenol-D was designed under closed magnetic flux return path, and permanent magnet for dc bias marnetic field, but high magnetic field should be applied to the transducer coil for high sound power and it brings temperature increase inside of the transducer. To improve this heat dissipation problem, we have designed an open magnetic circuit type transducer and we can get 200 dB (re. 1 Pa @ 1m) sound power for the input power of 650 VA.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1732-1735
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• 2003

In this paper, a DSP-based test apparatus for Control Rod Drive Mechanism (CRDM) that is used in nuclear power plants is described. Using this apparatus, we can test the mechanical and electrical characteristics of CRDM and obtain some information about how to improve the CRDM further and how to design a power controller to actuate the CRDM. Since firing angles can be directly applied to the gate-drive circuits of thyristors in the power controller by using this apparatus, the maximum and minimum values of firing angles within available limits are easily measured. Also step-current inputs help us investigate each coil's response characteristics. Therefore, we can easily find the range of control gains which enables a stable CRDM operation in insertion and withdrawal actions at high speed, mid speed, and low speed. Since this apparatus has a test mode in which an insertion or withdrawal action is divided into several phases so that the current command for each phase is given step by step, we may judge whether the CRDM works as expected or not. We also describe a fault detection capability of the test apparatus for the power controller by using discrete Fourier transform.