YeonKwan Moon

Reduction of Numerical Dispersion Error in 3-D ADI-MRTD Method With the Coarse Mesh

In order to reduce the numerical dispersion in three-dimensional alternating-direction implicit multiresolution time-domain scheme, a correction procedure is introduced. The numerical dispersion relation and the anisotropic correction parameters are considered. The reduction of the numerical dispersion is investigated for single frequency problem and wide-band simulation with the coarse mesh.

Design and Implement the Stimuli Capsule at In-vitro Experiment

Recently, the capsule endoscope has been developed to observe image from the inside intestine. Such a capsule endoscope does not have locomotion or hold by it self. To get proper diagnosis and meditation, it is necessary to control capsule from outside to enable to guide locomotion. The designed and implemented capsule has feasibility to contracts the small intestine by electrical stimulus from stimulus pad. When the small intestine is contracted by electrical stimulus, the capsule can move to opposite direction which can boost moving speed of the capsule or change moving direction. The implemented stimuli capsule always monitors excessive energy transmit and automatically shut down electrical stimuli to make more secure. Also the stimuli capsule goes to stand by mode to save battery, and reset by comparator circuit which is connected to two stimulus pad. To verify the design and implement stimuli capsule, in-vitro experiments are performed with pigs small intestine.

Implemented a wireless communication system for VGA capsule endoscope

Recently, several medical devices that use wireless communication are under development. In this paper, the small size frequency shift keying (FSK) transmitter and a monofilar antenna for the capsule endoscope, enabling the medical device to transmit VGA-size images of the intestine. To verify the functionality of the proposed wireless communication system, computer simulations and animal experiments were performed with the implemented capsule endoscope that includes the proposed wireless communication system. Several fundamental experiments are carried out using the implemented transmitter and antenna, and animal in-vivo experiments were performed to verify VGA image transmission.

Analysis of Periodic Stepped Impedance Ring Resonator by the Effect of Step Perturbation and Application of Dual-Mode Bandpass Filter

Dual-mode bandpass filter was designed by using periodic stepped impedance ring resonator with step perturbation. The periodic stepped impedance ring resonator has the effects of size reduction and harmonic suppression by changing characteristic impedance ratio. The perturbation for dual-mode generation was also easily controlled by characteristic impedance ratio, and the variation of dual-mode resonant frequencies and attenuation pole frequencies were analyzed by the effect of step perturbation. Chip capacitors were used for input/output coupling, and the variation of center frequency by the coupling capacitance and step perturbation was also considered. From the results, two types of 2 GHz dual-mode bandpass filter were fabricated in size of , those have different attenuation poles and bandwidths. The measured results of proposed bandpass filters showed a good agreement with the calculated estimations, and those have insertion loss of 2.52, 0.52 dB and 3 dB bandwidth of 4.03, 15.02 %, respectively.

Time Domain Scheme Based on Positive Sampling Basis Associated with Coifman Scaling Function

In order to simplify the Coifman scaling function based S-MRTD scheme for electromagnetic field problems, we develop the update formulations based on the positive sampling basis. We show the approximate interpolation property of the positive sampling basis associated with Coifman scaling function exactly. That makes the implementation of boundary condition, inhomogeneous media interface, and the total field computation simple. Actually the time domain scheme introduced in this paper has the merits of Coifman scaling function based S-MRTD and is simpler to formulate than S-MRTD. The some numerical results are provided to validate this work. The numerical results also validate the sampling property of Coifman scaling function.

Telemetry capsule for pressure monitoring in the gastrointestinal tract

As the cause and the treatment about gastrointestinal disease has been issued recently, the importance of measuring the pressure in the gastrointestinal tract has been increased. However, the conventional measurement methods of the pressure in the gastrointestinal tract cause the patients` pain and inconvenience as well as an inaccurate pressure measurement. In this paper, the pressure monitoring telemetry system has been designed and implemented for an accurate pressure measurement inside the gastrointestinal tract with minimizing pain and inconvenience. The pressure monitoring telemetry system is composed of a pressure measurement capsule and an external receiver. The capsule has been miniaturized into the same size of a vitamin tablet so that the capsule can be swallowed through the oral cavity. After the capsule acquires and encodes the pressure data in the gastrointestinal tract, the encoded pressure data are modulated by frequency shift keying (FSK) and transmitted with ultrahigh frequency (UHF) band signal to the outside of a body. The performance of the telemetry capsule for monitoring pressure in the gastrointestinal tract is demonstrated by the results of animal in-vivo experiments.