Heung-Ho Choi

Design and implementation of real-time security guard robot using CDMA networking

Progression of a mobile robot and communication techniques enables intelligent robot to be developed more versatilely. Through the ubiquitous robot control, paradigm of robot which performs specific tasks remotely has changing into intelligent robot to perform public and individual tasks. Especially, in the robot and security industry, security guard robot provides a variety of information to user and achieves its duty through the Web interface. The communication technique for these telepresence robot takes charge of the probability of various service in the robot industry. Last year, the interface for telepresence robot has developed over the Web or RF between robots, but these system has the demerits of limited distance or geographical limit to be established Internet link. In this paper, we propose the SG-robot (security guard robot) that can be operated and conduct surveillance the environment around itself anytime/anywhere using CDMA networking. SG-robot was able to solve those problems, conduct the surveillance task and communicate with between multi SG-robot and users over the cdma2000-1x communication network efficiently

Study on Changes in Shape of Denatured Area in Skull-mimicking Materials Using Focused Ultrasound Sonication

Recently, ultrasound therapy has become a new and effective treatment for many brain diseases. Therefore, skull-mimicking phantoms have been developed to simulate the skull and brain tissue of a human and allow further research into ultrasound therapy. In this study, the suitability of various skull-mimicking materials(HDPE, POM C, Acrylic) for studies of brain-tumor treatments was evaluated using focused ultrasound. The acoustic properties of three synthetic resins were measured. The skull-mimicking materials were then combined with an egg white phantom to observe the differences in the ultrasound beam distortion according to the type of material. Highintensity polyethylene was found to be suitable as a skull-mimicking phantom because it had acoustic properties and a denatured-area shape that was close to those of the skull,. In this study, a skull-mimicking phantom with a multi-layer structure was produced after evaluating several skullmimicking materials. This made it possible to predict the denaturation in a skull in relation to focused ultrasound. The development of a therapeutic protocol for a range of brain diseases will be useful in the future.

The study of correlation between foot-pressure distribution and scoliosis

The foot-pressure while walking represents the status of the geometrical balance of the human’s musculoskeletal system. The foot-pressure in unbalanced anatomical position causes physiological disorders to the human body and accumulates stress to the musculoskeletal system. Repetitious abnormal impacts become the direct cause of vertebrae disease. The purpose of this study is to evaluate the correlation between the degree of scoliosis and the foot-pressure distribution in twenty males who have no clinical history of vertebral disease. The F-scan system(Tekscan Inc., USA, 850Hz sampling frequency) was used to measure the foot-pressure. The sole was divided into 7 regions of interest(ROI), and an analysis was performed for these ROIs. The degree of scoliosis was expressed as the angle, calculated with X-ray image, which showed lumbar vertebra number 5 to thoracic vertebra number 7. This angle was used to evaluate the correlations with the result of the foot-pressure analysis. Measurement of footpressure on the subjects was executed using the same protocol. The correlation between the measured foot-pressure and the degree of scoliosis was evaluated under a 0.05 level of significance. The results of the evaluation revealed the tendency that, as the degree of scoliosis increases, a difference in footpressure also increases. The variables used for analysis showed high correlations. The obtained results will be used to determine the occurrence of vertebra and lower limb disease and to present a qualitative evaluation basis for the rehabilitation of patients with lower limb disease.

The Development of Muscle Training System Using the Electromyogram and Interactive Game for Physical Rehabilitation

In this study, muscle training system was developed for effective rehabilitation treatment. This system consists of the electromyogram (EMG) acquisition module, the graphic user interface (GUI) system, and game contents of each channel mode. EMG acquisition module acquires EMG signals and transmits to GUI. GUI performs to control the direction in for game operation using acquired EMG signals. The obtained data were analyzed using laboratory-developed software based on Microsoft Foundation Class (MFC) of Visual Studio 2008. The games were developed as each-channel mode for various exercises in rehabilitation. All the games were implemented in Flash CS4 using Action Script 2.0. This system was to overcome the boredom and monotony in rehabilitation. We proposed the method which improves the patient’s participation willingness and motivates them in rehabilitation.

Development of neural network based plasma monitoring system for laser welding quality analysis

Neural networks are shown to be effective in being able to distinguish incomplete penetration-like weld defects by directly analyzing the plasma which is generated on each impingement of the laser on the materials. The performance is similar to that of existing methods based on extracted feature parameters. In each case around 93% of the defects in a database derived from 100 artificially produced defects of known types can be placed into one of two classes: incomplete penetration and bubbling. The present method based on classification using plasma is faster, and the speed is sufficient to allow on-line classification during data collection.

Classification of the EMG Signal using Cascaded Classifier

This paper describes an approach for classifying electromyographic (EMG) signals using the multilayer perceptrons (MLP’s) and the hidden markov models (HMM’s). In this paper, we propose the combination of MLP’s and HMM’s cascaded structure to increase discrimination rates of myoelectric patterns. Feature sets based upon the short-time Fourier transform, the wavelet transform, and the wavelet packet transform for discriminating signals represent active of motions are applied and compared. This strategy is proposed to overcome weak discrimination and to consider dynamic properties of EMG signlas.

Thermal characteristics of non-biological vessel phantoms for treatment of varicose veins using high-intensity focused ultrasound

The ultrasonic treatment of varicose veins uses high-intensity focused ultrasound, in which a blood vessel is contracted by converting acoustic energy into thermal energy. In this study, we propose a phantom of varicose veins that can be applied for the efficient evaluation of ultrasonic treatment in varicose veins. The proposed phantom consisted of glycerol base tissue equivalent material, vessel mimic tube, and blood mimic substances. The vessel mimic tube was placed inner glycerol phantom and it was filled with blood mimic substances. Blood-mimicked substances are prepared by adjusting the concentration of the glycerol solution to be similar to the acoustic properties of the blood, and vessel-mimicking materials are selected by measuring acoustic properties and thermal shrinkage of various materials in a heat-shrinkable tube. The blood vessels surrounding the tissue are replaced with the phantom similar to glycerol-based organization, and venous blood flow is implemented using a DC motor. The heating characteristics according to the ultrasonic wave using the manufactured varicose veins phantom were evaluated. As the sound wave irradiation time and power increased, the contractility of the vessel mimicking materials and the temperature of the surrounding tissues were increased. When the blood-mimicking material was circulated, the highest temperature in the focused region and the contractility of vessel mimicking materials were reduced under the same conditions as used for sonication. The manufactured phantom may contribute to the treatment of varicose veins and can be used to predict the ultrasonic therapeutic efficiency of varicose veins.

Evaluation of Acoustic, Thermal, and Morphological Properties in the Egg White Phantom

The egg white phantom is a thermal lesion visualization phantom able to illustrate a thermal lesion. It is often used to evaluate the performance of HIFU and is less expensive than the BSA phantom. This study determined the optimal phantom composition for evaluated therapeutic ultrasound machines by varying the egg white concentration in the egg white phantom and demonstrated its utility as a therapeutic ultrasound phantom. The egg white phantom at varying egg white concentrations (10-40% in 10% intervals) was fabricated, and its thermal properties and acoustic properties were assessed. In addition, the size and shape of the formed lesion were compared between the egg white phantom and bovine liver tissue according to the electrical power. The results showed that 30% egg white phantom was optimal for the performance evaluation due to its thermal and acoustic properties. The generated thermal lesions formed sequentially as a cigar, ellipse, tadpole, and cone shapes according to the electrical power; a similar tendency was observed in the liver tissue. Hence, we conclude that the egg white phantom will prove useful in quantitatively evaluating the thermal effects of therapeutic ultrasound.

A Study on the Safety and Performance Test Guideline of Low Intensity Therapeutic Ultrasound Device

In this study, we suggested the performance and safety testing guideline for low intensity pulsed ultrasound (LIPUS) represented by the ultrasound fracture treatment device and cartilage treatment device and low intensity focused ultrasound (LIFU) represented by ultrasonic face lifting device. For these study, the international standards and management regulations of Korea, Japan and United State were analyzed. And the usefulness and applicability were evaluated by testing with commercial equipment and reflecting the views of the industry and experts. As a result of this study, the safety and performance test guidelines for low intensity therapeutic ultrasound device were proposed by presenting the 10 items for LIPUS and 12 items for LIFU. The suggested guidelines are considered a high utilization in the domestic testing and approval authorities. And they are also thought to be useful to new technology development.

Quantitative Rehabilitation Extent Monitoring for Unilateral Lower Extremity Disabled Patients using Simulated Gait Pattern Analysis

Abstract: In this paper, to quantitatively evaluate the degree of rehabilitation for the disabled of unilateral lowerextremity, we compared the EMG pattern of normal and simulated abnormal gait. The EMG signal was measuredat a rate of 1 kHz on the quadriceps and biceps femoris, the pressure sensor was attached to the sole in order todistinguish the gait cycle. Integrated EMG (IEMG) was obtained by the gait cycle, and classified four patterns thatwere the normal gait pattern, amplitude decrease pattern, reversed pattern, and irregular pattern. For comparisonof the patterns, a curve fitting was performed using the trigonometric functions. The result of curve fitting, themethod using a variable A that corresponds to the amplitude of the regression curve was able to distinguish thereverse pattern and remaining pattern. The coefficient of determination (R 2 ) representing coincidence of the patternof the regression curve and EMG was confirmed the biggest value at the normal gait. Therefore, the degree of normalgait can be confirmed using the coefficient of determination. This results show that it is possible to quantitativelyconfirm the degree of unilateral lower extremity disabled rehabilitation, and it will be contributed to the study of effi-cient rehabilitation methods by objective analysis.Key words: Gait analysis, IEMG, Curve fitting, Comparison of EMG pattern, Evaluation of rehabilitation