Open Science Research Excellence

Chang Yong Ko

Publications

6

Publications

6
1775
Relationship between Functional Gastrointestinal Disorders and Risk Factors: A Biomechanical Analysis
Abstract:

Functional gastrointestinal disorders (FGID) affect millions of people spread all age regardless of race and sex. Emotional stress and obesity have been associated with increased reporting of gastrointestinal (GI) symptoms, but the relationship between FGID and risk factors (emotional stress or obesity) is unclear. Our aim was to assess the changes of the mechanical characteristics on the gastrointestinal tracts of the mentally fatigued obese and normal rat models. Finally, using the physical characteristics with micro-indentation test, we made a close investigation into the relation between FGID and risk factors quantitatively.

Keywords:
Functional gastrointestinal disorders, Risk Factors,Mechanical Characteristics, Gastrointestinal Tract.
5
3680
Long-Term Study for the Effect of Ovariectomy on Rat Bone - Use of In-Vivo Micro-CT -
Abstract:
In the present study, changes of morphology and mechanical characteristics in the lumbar vertebrae of the ovariectomised (OVX) rat were investigated. In previous researches, there were many studies about morphology like volume fraction and trabecular thickness based on Micro - Computed Tomography (Micro - CT). However, detecting and tracking long-term changes in the trabecular bone of the lumbar vertebrae for the OVX rat were few. For this study, one female Sprague-Dawley rat was used: an OVX rat. The 4th Lumbar of the OVX rat was subjected to in-vivo micro-CT. Detecting and tracking long-term changes could be investigated in the trabecular bone of the lumbar vertebrae for an OVX rat using in-vivo micro-CT. An OVX rat was scanned at week 0 (just before surgery), at week 4, at week 8, week 16, week 22 and week 56 after surgery. Finite element (FE) analysis was used to investigate mechanical characteristics of the lumbar vertebrae for an OVX rat. When the OVX rat (at week 56) was compared with the OVX rat (at week 0), volume fraction was decreased by 80% and effective modulus was decreased by 75%.
Keywords:
OVX rats, Trabecular bone, In-vivo Micro-CT, FE analysis
4
4505
Heat Treatment and Rest-Inserted Exercise Enhances EMG Activity of the Lower Limb
Abstract:
Prolonged immobilization leads to significant weakness and atrophy of the skeletal muscle and can also impair the recovery of muscle strength following injury. Therefore, it is important to minimize the period under immobilization and accelerate the return to normal activity. This study examined the effects of heat treatment and rest-inserted exercise on the muscle activity of the lower limb during knee flexion/extension. Twelve healthy subjects were assigned to 4 groups that included: (1) heat treatment + rest-inserted exercise; (2) heat + continuous exercise; (3) no heat + rest-inserted exercise; and (4) no heat + continuous exercise. Heat treatment was applied for 15 mins prior to exercise. Continuous exercise groups performed knee flexion/extension at 0.5 Hz for 300 cycles without rest whereas rest-inserted exercise groups performed the same exercise but with 2 mins rest inserted every 60 cycles of continuous exercise. Changes in the rectus femoris and hamstring muscle activities were assessed at 0, 1, and 2 weeks of treatment by measuring the electromyography signals of isokinetic maximum voluntary contraction. Significant increases in both the rectus femoris and hamstring muscles were observed after 2 weeks of treatment only when both heat treatment and rest-inserted exercise were performed. These results suggest that combination of various treatment techniques, such as heat treatment and rest-inserted exercise, may expedite the recovery of muscle strength following immobilization.
Keywords:
Electromyography, Heat Treatment, Muscle, Rest-Inserted Exercise.
3
4545
Experimental Technique for Vibration Reduction of a Motor Pumpin Medical Device
Abstract:

Many medical devices are driven by motor pumps. Some researchers reported that the vibration mainly affected medical devices using a motor pump. The purpose of this study was to examine the effect of stiffness and damping coefficient in a 3-dimensional (3D) model of a motor pump and spring. In the present paper, experimental and mathematical tests for the moments of inertia of the 3D model and the material properties were investigated by an INSTRON machine. The response surfaces could be generated by using 3D multi-body analysis and the design of experiment method. It showed that differences in contours of the response surface were clearly found for the particular area. Displacement of the center of the motor pump was decreased at K≈2000 N/M, C≈12.5 N-sec/M. However, the frequency was increased at K≈2000 N/M, C≈15 N-sec/M. In this study, this study suggested experimental technique for vibration reduction for a motor pump in medical device. The combined method suggested in this study will greatly contribute to design of medical devices concerning vibration and noise intervention.

Keywords:
Motor pump, Spring, Vibration reduction, Medicaldevices, Moment of Inertia
2
11310
Suggestion of Ultrasonic System for Diagnosis of Functional Gastrointestinal Disorders: Finite Difference Analysis, Development and Clinical Trials
Abstract:
The disaster from functional gastrointestinal disorders has detrimental impact on the quality of life of the effected population and imposes a tremendous social and economic burden. There are, however, rare diagnostic methods for the functional gastrointestinal disorders. Our research group identified recently that the gastrointestinal tract well in the patients with the functional gastrointestinal disorders becomes more rigid than healthy people when palpating the abdominal regions overlaying the gastrointestinal tract. Objective of current study is, therefore, identify feasibility of a diagnostic system for the functional gastrointestinal disorders based on ultrasound technique, which can quantify the characteristics above. Two-dimensional finite difference (FD) models (one normal and two rigid model) were developed to analyze the reflective characteristic (displacement) on each soft-tissue layer responded after application of ultrasound signals. The FD analysis was then based on elastic ultrasound theory. Validation of the model was performed via comparison of the characteristic of the ultrasonic responses predicted by FD analysis with that determined from the actual specimens for the normal and rigid conditions. Based on the results from FD analysis, ultrasound system for diagnosis of the functional gastrointestinal disorders was developed and clinically tested via application of it to 40 human subjects with/without functional gastrointestinal disorders who were assigned to Normal and Patient Groups. The FD models were favorably validated. The results from FD analysis showed that the maximum displacement amplitude in the rigid models (0.12 and 0.16) at the interface between the fat and muscle layers was explicitly less than that in the normal model (0.29). The results from actual specimens showed that the maximum amplitude of the ultrasonic reflective signal in the rigid models (0.2±0.1Vp-p) at the interface between the fat and muscle layers was explicitly higher than that in the normal model (0.1±0.2 Vp-p). Clinical tests using our customized ultrasound system showed that the maximum amplitudes of the ultrasonic reflective signals near to the gastrointestinal tract well for the patient group (2.6±0.3 Vp-p) were generally higher than those in normal group (0.1±0.2 Vp-p). Here, maximum reflective signals was appeared at 20mm depth approximately from abdominal skin for all human subjects, corresponding to the location of the boundary layer close to gastrointestinal tract well. These findings suggest that our customized ultrasound system using the ultrasonic reflective signal may be helpful to the diagnosis of the functional gastrointestinal disorders.
Keywords:
Finite Difference (FD) Analysis, FunctionalGastrointestinal Disorders, Gastrointestinal Tract, UltrasonicResponses.
1
13752
Ultrasonic System for Diagnosis of Functional Gastrointestinal Disorders: Development, Verification and Clinical Trials
Abstract:
Functional gastrointestinal disorders affect millions of people spread all age regardless of race and sex. There are, however, rare diagnostic methods for the functional gastrointestinal disorders because functional disorders show no evidence of organic and physical causes. Our research group identified recently that the gastrointestinal tract well in the patients with the functional gastrointestinal disorders becomes more rigid than healthy people when palpating the abdominal regions overlaying the gastrointestinal tract. Aim of this study is, therefore, to develop a diagnostic system for the functional gastrointestinal disorders based on ultrasound technique, which can quantify the characteristic above related to the rigidity of the gastrointestinal tract well. Ultrasound system was designed. The system consisted of transmitter, ultrasonic transducer, receiver, TGC, and CPLD, and verified via a phantom test. For the phantom test, ten soft-tissue specimens were harvested from porcine. Five of them were then treated chemically to mimic a rigid condition of gastrointestinal tract well, which was induced by functional gastrointestinal disorders. Additionally, the specimens were tested mechanically to identify if the mimic was reasonable. The customized ultrasound system was finally verified through application to human subjects with/without functional gastrointestinal disorders (Normal and Patient Groups). It was identified from the mechanical test that the chemically treated specimens were more rigid than normal specimen. This finding was favorably compared with the result obtained from the phantom test. The phantom test also showed that ultrasound system well described the specimen geometric characteristics and detected an alteration in the specimens. The maximum amplitude of the ultrasonic reflective signal in the rigid specimens (0.2±0.1Vp-p) at the interface between the fat and muscle layers was explicitly higher than that in the normal specimens (0.1±0.0Vp-p). Clinical tests using our customized ultrasound system for human subject showed that the maximum amplitudes of the ultrasonic reflective signals near to the gastrointestinal tract well for the patient group (2.6±0.3Vp-p) were generally higher than those in normal group (0.1±0.2Vp-p). Here, maximum reflective signals was appeared at 20mm depth approximately from abdominal skin for all human subjects, corresponding to the location of the boundary layer close to gastrointestinal tract well. These results suggest that newly designed diagnostic system based on ultrasound technique may diagnose enough the functional gastrointestinal disorders.
Keywords:
Functional Gastrointestinal Disorders, DiagnosticSystem, Phantom Test, Ultrasound System.