Yigon Kim

TZ-Source Inverters

A new family of single-stage high-step-up boost voltage inverters based on transformers is proposed, called TZ-source inverters. By replacing two inductors in the classical Z-source inverter with two transformers, the proposed inverter produces a very high boost voltage gain when the turn ratio of the transformers is larger than 1. Compared to the trans-Z-source inverters, the proposed TZ-source inverter uses a lower transformer turn ratio, which reduces the transformers size and weight while producing the same output voltage gain. The extension of the proposed inverter topology to dc-link-type and embedded-type topologies is presented. The operating principles, analysis, and simulation results are shown. To verify the performance of the proposed TZ-source inverter, a laboratory prototype was constructed and operated with 60-V dc input. The simulation and experimental results verified that the converter has high-step-up inversion ability.

Secure Communication using Embedding Drive Synchronization

In this paper, We introduce an embedding driven synchronization method using SC-CNN(State-Controlled Cellular Neural Network) which has the purpose to secure communication method through the embedding driven synchronization method in the SC-CNN. we proposed new embedding driven synchronization that this method is only using one state variable compare to the general driven synchronization methods which is using all state variables. In this paper, We achieved the usage of embedding driven synchronization and we also applied it to secure communication.

Obstacle Avoidance Methods in the Chaotic Mobile Robot with Integrated some Chaos Equation

In this paper, we propose a method to avoid obstacles that have unstable limit cycles in a chaos trajectory surface. We assume all obstacles in the chaos trajectory surface have a Van der Pol equation with an unstable limit cycle. When a chaos robot meets an obstacle in an Arnold equation or Chua`s equation trajectory, the obstacle reflects the robot. We also show computer simulation results of Arnold equation and Chua`s equation and random walk chaos trajectories with one or more Van der Pol obstacles and compare the coverage rates of each trajectory. We show that the Chua`s equation is slightly more efficient in coverage rates when two robots are used, and the optimal number of robots in either the Arnold equation or the Chua`s equation is also examined.

A study on Generalized Synchronization in the State-Controlled Cellular Neural Network(SC-CNN)

In this paper, we introduce a generalized synchronization method and secure communication in the State-Controlled Cellular Neural Network (SC-CNN). We make a SC-CNN using the n-double scroll. A SC-CNN is created by applying identical n-double scroll or non-identical n-double scroll and Chuas oscillator with weak coupled method to each cell. SC-CNN synchronization was achieved using GS(Generalized Synchronization) method between the transmitter and receiver about each state variable in the SC-CNN. In order to secure communication, we have synthesizing the desired information with a SC-CNN circuit by adding the information signal to the hyper-chaos signal using the SC-CNN in the transmitter. And then, transmitting the synthesized signal to the ideal channel, we confirm secure communication by separating the information signal and the SC-CNN signal in the receiver.

Chaotic behavior analysis in the mobile robot of embedding some chaotic equation with obstacle

In this paper, we propose that the chaotic behavior analysis in the mobile robot of embedding some chaotic such as Chua`s equation, Arnold equation with obstacle. In order to analysis of chaotic behavior in the mobile robot, we apply not only qualitative analysis such as time-series, embedding phase plane, but also quantitative analysis such as Lyapunov exponent In the mobile robot with obstacle. We consider that there are two type of obstacle, one is fixed obstacle and the other is VDP obstacle which have an unstable limit cycle. In the VDP obstacles case, we only assume that all obstacles in the chaos trajectory surface in which robot workspace has an unstable limit cycle with Van der Pol equation.

Oil-Tank Weld Detection Using EMAT

Tanks are typically used for the storage of oil by the petrochemical industry, and the storage quality is largely determined by the safety of the equipment. Recently, Electromagnetic Acoustic Trans...

Preliminary study for the personal handheld device based snoring detection in ordinary sleep situation.

Snoring is one of the representative phenomena of the sleep disorder and detection of snoring is quite important for improving quality of daily human life. The purpose of this research is to define the noises of the ordinary sleep situation and to find its characteristics as a preliminary research of snoring detection. Differently from previous snoring researches, we use a built-in sound recording system of Smartphone for practical use in ordinary sleep condition, and recording was carried out in a general private bedroom. Especially, we designed the experimental protocol, including the various noises could be frequently occurred during sleep such as cough, music, talking, alarm, door open/close, fan, radio and footstep to make closer to the actual sleep circumstance. The sound data set was recorded during actual sleep from 10 normal subjects. Totally 44 snoring data set and 75-noise dataset is acquired and analyzed.

Phased array simulation for evaluation of weld in offshore chain

Offshore chain may have the flaws such as the lack of fusion in the weld. The ultrasonic testing (UT) has performed to detect the lack of fusion in the weld. The conventional UT has been performed by the pulse-echo and/or tandem method; the probe is positioned on the straight part with cylindrical surface but has not completely secured the reliability of the flaw detection in the offshore chain. Phased array ultrasonic testing (PAUT) can generate the ultrasonic focused beam and sweep the ultrasonic beam with multiple angles, so it is possible to inspect the wide area on a fixed probe position. Therefore, PAUT can inspect the full area of the weld in the offshore chain as moved with single array probe in a finite area. The phased array probe is positioned off the straight part with the spherical surface. And, the procedure of PAUT and the criteria of the detection and sizing of the flaw are not established. In this study, ultrasonic beam generated with array probe in offshore chain is simulated with CIVA simulation software, and sound pressure distribution is analyzed for establishing the criteria of the flaw sizing.

Development of Health Monitoring System Using Self Magnetization Magnetostrictive Sensor

This thesis examines the development and application of `Health Monitoring System` which monitors periodically the state of a pipe of petrochemical plant by using magnetostrictive sensor technology. The existing guided-wave inspection methods cannot be applied to welding part inspection in pipe, and has a limit of precision when applied to general parts because of noise, reflected waves, and so on. This technology uses the information on displacement of a defect through periodic monitoring, which makes more precise inspection, and can be utilized very usefully in a petrochemical plant.

Experimental Verification and Analysis for Ability of Defect Detection with Angle for Axis Direction of Guided Wave Using Magnetostrictive Sensor

In this paper we induced it by using disperse which is wave analysis program developed by Imperial College of United Kingdom. In this paper we sent and received longitudinal mode and torisional mode of guided wave using magnetostrictive sensor for test plate of mock-up with artificial defect of 90°, 75° 60° for axis direction of pipe. We review each characteristics of each mode compare with Vpp along with angle for axis direction of received defect signal.