• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.580-581
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• 2011

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.42-43
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• 2011

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.93-100
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• 2016

Since the sodium-cooled fast reactor is operated in a hostile environment due to the use of liquid sodium as its coolant, advanced techniques for in-service inspection are required to periodically verify the integrity of the reactor. This paper presents the development of in-service inspection techniques for Proto-type Generation IV Sodium-cooled Fast Reactor. First, the 10 m long plate-type ultrasonic waveguide sensor has been developed for in-service inspection of reactor internals, and its feasibility was verified through several under-water and under-sodium experiments. Second, the combined inspection system for in-service inspection of ferromagnetic steam generator tubes has been developed. The remote field eddy current testing and magnetic flux leakage testing can be conducted simultaneously by using the developed inspection system, and the detectability was demonstrated through several damage detection experiments. Finally, the electro-magnetic acoustic transducer which can withstand high temperature and be installable in the remote operated vehicle has been developed for in-service inspection of the reactor vessel, and its detectability was investigated through damage detection experiments.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.9
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• pp.845-852
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• 2012

Recently, wireless power transfer technology is ready to be commercialized in consumer electronics. It draws attention from not only experts but also public because of its convenience and huge market. However, previous technologies such as magnetic resonance and induction coupling have limited applications because of its short transfer distance compared to device size and magnetic intensity limitation on the safety of body exposure. As an alternative, ultrasonic wireless power transfer technology is proposed. The ultrasonic wireless power transfer system is composed of transmitter which converts electrical energy to ultrasonic energy and receiver which converts the ultrasonic energy to the electrical energy again. This paper is focused on the development of high energy conversion efficiency of ultrasonic transmitter. Optimal transfer frequency is calculated based on the acoustic radiation and damping effect. The transmitter is designed through numerical analysis, and is manufactured to match the optimal transfer frequency with the size of 100 mm diameter, 12.2 mm thickness plate. The energy conversion efficiency of about 13.6 % at 2 m distance is obtained, experimentally. This result is quite high considered with the device size and the power transfering distance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.771-776
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• 2012

Recently, wireless power transfer technology is ready to be commercialized in consumer electronics. It draws attention of not only experts but also public because of its convenience and huge market. However, previous technologies such as magnetic resonance and induction coupling have limited applications because of its short transfer distance compared to device size and magnetic intensity limitation for the safety of body exposure. As an alternative, ultrasonic wireless power transfer technology is proposed. The ultrasonic wireless power transfer system is composed of transmitter which converts electrical energy to ultrasonic energy and receiver which converts the ultrasonic energy to the electrical energy again. This paper is focused on the development of high energy conversion efficiency of ultrasonic transmitter. Optimal transfer frequency is calculated based on the acoustic radiation and damping effect. The transmitter is designed through numerical analysis, and is manufactured to match the optimal transfer frequency with the size of 100mm diameter, 12.2 mm thickness plate. The energy conversion efficiency of about 13.6% at 2m distance is obtained, experimentally. This result is quite high considered with the device size and the power transfer distance.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.474-479
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• 1993

An interferometric fiber-optic magnetic field sensor is constructed by bonding a Co-Fe-B metallic glass transducer developed here by the melt-spun method to a single mode fiber arm in the fiber Mach-Zehnder interferometer and is tested. The bias field for the peak ac-sensitivity was observed near 0.97 Oe and the minimum detectable magnetic field was 3.9${\times}10^{-5}$ Oe(rms)/${\sqrt{Hz}}$ a 3 kHz. The output of the ac field sensor becomes saturated near the input signal level of 1 Oe(rms). The Co- Fe-B transducer exhibits peak response near 500 Hz.

• Journal of the Korean Magnetics Society
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• v.14 no.4
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• pp.138-142
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• 2004

Uncertainty and characteristics of the developed current sensor by means of two identically wound magnetic cores forming a ring like for measurement of a low DC current such as leakage current was described in this paper. This transducer consists of a sensor type of a current transformer, peak value detectors, a reference alternating low frequency voltage oscillator, precision measuring circuits to measure the output signals of sensor with harmonics, and can be measured up to 2 A at DC current. The resolution and sensitivity of the sensor were 0.1㎃ and 10㎷/㎃, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.3
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• pp.23-31
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• 1995

The sending characteristics of the non-contact type displacement transducers can affect the performances of the magnetic bearing systems when they support the rotating shaft. The probe type displacement sensor detects not only the displacement of the rotor at the sensing position but also the surface irregularitis of the rotor such as surface roughnessand roundness errors. If there exist such measuring errors, the magnetic bearing can not apply proper force against the rotor displacements for the detected signal is the input to the magnetic bearing controllers. The cylindrical shape capacitive transducer can detect the rotor displacement by the integral sum of the charges which are formed between the sensor plates and rotor so that it can reduce the detecting errors induced by the surface irregularities of the rotor. By theore- tical analysis, we compared the sensing characteristics of the cylindrical shape capacitive transducers for the rotors that have some sinusoidal irregularities with that of the ideal probe type displacement transducers.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.2
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• pp.187-192
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• 2002

The open-connect type eddy current transducer for the flaw detection in continuously connected pipelines was developed. This eddy current transducer is for the on-line inspection of the tubes in industries, to which commercial encircling probes are not applicable. The excitation coil that consists of a ribbon type cable and a flat connector can be opened and closed on purpose. The sensing coils of this transducer are circumferentially arrayed near the outside of the tube wall but axially displaced from the exciter by about one and half tube diameter. In application to steel tubes, and the performance of this transducer was evaluated as a little behind those of magnetic saturation type in signal to noise ratio and flaw size decision, but usable to detect or to locate large size flaws in steel tubes. Surface cracks deeper than 19% of the tube thickness could be detected with good signal to noise ratio.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.243-247
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• 1996

Electro-magnetic type implantable middle ear hearing aid has been empirically developed. But for further improvement of the system performance more quantitative approach is necessary. In this paper, we analyzed vibrating transducer which is most important to design the system, appropriate for given hearing level, and implemented it. Using this transducer, implantable hearing aid system are developed. To verify the design process, we experimented with driving metal strip by the developed system. From the experiment, frequency response of implemented device showed good characteristic at audio frequency and we confirmed that each part of the developed system operated well.