• Journal of Biomedical Engineering Research
• /
• v.25 no.6
• /
• pp.471-478
• /
• 2004

Electromyogram (EMC) signal generated by voluntary contraction of muscles is often used in a rehabilitation devices such as an upper limb prosthesis because of its distinct output characteristics compared to other bio-signals. This paper proposes an EMG-based human-computer interface (HCI) for the control of the above-elbow prosthesis or the wheelchair. To control such rehabilitation devices, user generates four commands by combining voluntary contraction of two different muscles such as levator scapulae muscles and flexor-extensor carpi ulnaris muscles. The muscle contraction is detected by comparing the mean absolute value of the EMG signal with a preset threshold value. However. since the time difference in muscle firing can occur when the patient tries simultaneous co-contraction of two muscles, it is difficult to determine whether the patient's intention is co-contraction. Hence, the use of the comparison method using a single threshold value is not feasible for recognizing such co-contraction motion. Here, we propose a novel method using double threshold values composed of a primary threshold and an auxiliary threshold. Using the double threshold method, the co-contraction state is easily detected, and diverse interface commands can be used for the EMG-based HCI. The experimental results with real-time EMG processing showed that the double threshold method is feasible for the EMG-based HCI to control the myoelectric prosthetic hand and the powered wheelchair.

• Clinics in Shoulder and Elbow
• /
• v.17 no.2
• /
• pp.50-56
• /
• 2014

Background: To assess the clinical outcomes of short-term oral corticosteroid therapy for impingement syndrome of the shoulder and determine whether it can be substituted as an alternative to the intra-articular injection. Methods: The clinical outcomes of the 173 patients, the oral steroid group (n=88) and the injection group (n=85), were measured at 3 weeks, 2, 4, and 6 months postoperatively. The clinical outcomes were assessed by measuring the the University of California at Los Angeles (UCLA) score, visual analog scale (VAS) and range of motion (ROM) at every follow-up. Any complications and recurrence rate were noted. A relationship between the treatment outcomes and factors such as demographic factors, clinical symptoms and radiographic findings were determined. Results: No difference was observed in VAS and UCLA scores between the two groups, but forward flexion and internal rotation of ROM were significantly improved in the injection group at the 2nd and 4th postoperative month (p < 0.05). At 6th postoperative month, recurrence rate of symptoms was 26% in the oral steroid group and 22% in the injection group. No major adverse effects were observed. When the clinical outcomes of the oral steroid group were compared to either demographic, clinical symptoms, or radiographic findings, UCLA score was found to be significantly low (p < 0.05) in patients with joint stiffness and UCLA score, whereas VAS score was significantly improved in patients with night pain (p < 0.05). Conclusions: Short-term low-dose oral corticosteroid therapy of impingement syndrome showed comparable clinical outcomes to intra-articular injection without any remarkable adverse effects. Low-dose oral steroids can be regarded as a partial alternative to intra-articular injection for the initial therapy of impingement syndrome of the shoulder.

• Journal of Navigation and Port Research
• /
• v.42 no.1
• /
• pp.1-8
• /
• 2018

This study covers the selection of systems measuring the behaviour of the slender structure in the underwater environment and its performance assessment. From a comparison of an instrumentation system that can measure the continuous behaviour along the entire length of the slender structure, the underwater camera system is finally selected as the most appropriate semi-permanent measurement system for Deep-sea Ocean Engineering Basin of KRISO. An experiment on the rigid pipes for a basic performance evaluation of the underwater camera is conducted in this study. The motion of a top excited rigid pipe is measured with the utilization of the underwater camera system. The performance of the underwater camera is evaluated by comparing the movement of a pipe measured by the underwater camera with the measured input signals. Through the top excitation experiment for the slender structure, the real-time three-dimensional measurement of the underwater camera system is qualitatively evaluated in this case. The developed underwater camera system can apply to the system to measure dynamic behaviour of a slender structure and mooring line in Deep Ocean Engineering Basin.

• Journal of KIISE
• /
• v.42 no.5
• /
• pp.609-620
• /
• 2015

Viewers of videos are likely to absorb more information from the part of the screen that attracts visual attention. This fact has led to the visual attention models that are being used in producing and evaluating videos. In this paper, we investigate the factors that are significant to visual attention and the mathematical form of the visual attention model. We then estimated the visual attention probability using the statistical design of experiments. The analysis of variance (ANOVA) verifies that the motion velocity, distance from the screen, and amount of defocus blur affect human visual attention significantly. Using the response surface modeling (RSM), we created a visual attention score model that concerns the three factors, from which we calculate the visual attention probabilities (VAPs) of image pixels. The VAPs are directly applied to existing gradient based 3D effect perception measurement. By giving weights according to our VAPs, our algorithm achieves more accurate measurement than the existing method. The performance of the proposed measurement is assessed by comparing them with subjective evaluation as well as with existing methods. The comparison verifies that the proposed measurement outperforms the existing ones.

• Journal of Korean Neurosurgical Society
• /
• v.61 no.6
• /
• pp.680-688
• /
• 2018

Objective : To mitigate the risk of iatrogenic instability, new posterior decompression techniques able to preserve musculoskeletal structures have been introduced but never extensively investigated from a biomechanical point of view. This study was aimed to investigate the impact on spinal flexibility caused by a unilateral laminotomy for bilateral decompression, in comparison to the intact condition and a laminectomy with preservation of a bony bridge at the vertebral arch. Secondary aims were to investigate the biomechanical effects of two-level decompression and the quantification of the restoration of stability after posterior fixation. Methods : A universal spine tester was used to measure the flexibility of six L2-L5 human spine specimens in intact conditions and after decompression and fixation surgeries. An incremental damage protocol was applied : 1) unilateral laminotomy for bilateral decompression at L3-L4; 2) on three specimens, the unilateral laminotomy was extended to L4-L5; 3) laminectomy with preservation of a bony bridge at the vertebral arch (at L3-L4 in the first three specimens and at L4-L5 in the rest); and 4) pedicle screw fixation at the involved levels. Results : Unilateral laminotomy for bilateral decompression had a minor influence on the lumbar flexibility. In flexion-extension, the median range of motion increased by 8%. The bone-preserving laminectomy did not cause major changes in spinal flexibility. Two-level decompression approximately induced a twofold destabilization compared to the single-level treatment, with greater effect on the lower level. Posterior fixation reduced the flexibility to values lower than in the intact conditions in all cases. Conclusion : In vitro testing of human lumbar specimens revealed that unilateral laminotomy for bilateral decompression and bone-preserving laminectomy induced a minor destabilization at the operated level. In absence of other pathological factors (e.g., clinical instability, spondylolisthesis), both techniques appear to be safe from a biomechanical point of view.

• The Journal of the Korea Contents Association
• /
• v.9 no.9
• /
• pp.97-104
• /
• 2009

This paper describes comparison and analysis of methodology which enables us in order to search the projection technique of optimum for projection in the plane. For this methodology, we applies the high-dimensional facial motion capture data respectively in linear and nonlinear projection techniques. The one core element of the methodology is to applies the high-dimensional facial expression data of frame unit in PCA where is a linear projection technique and Isomap, MDS, CCA, Sammon's Mapping and LLE where are a nonlinear projection techniques. And another is to find out the methodology which distributes in this low-dimensional space, and analyze the result last. For this goal, we calculate the distance between the high-dimensional facial expression frame data of existing. And we distribute it in two-dimensional plane space to maintain the distance relationship between the high-dimensional facial expression frame data of existing like that from the condition which applies linear and nonlinear projection techniques. When comparing the facial expression data which distribute in two-dimensional space and the data of existing, we find out the projection technique to maintain the relationship of distance between the frame data like that in condition of optimum. Finally, this paper compare linear and nonlinear projection techniques to projection high-dimensional facial expression data in low-dimensional space and analyze it. And we find out the projection technique of optimum from it.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.12 no.1
• /
• pp.79-87
• /
• 2008

Seismic performance evaluation of structure requires an estimation of the structural performance in terms of displacement demand imposed by earthquakes on the structure. Incremental Dynamic Analysis(IDA) is a analysis method that has recently emerged to estimate structural performance under earthquakes. This method can obtained the entire range of structural performance from the linear elastic stage to yielding and finally collapse by subjecting the structure to increasing levels of ground acceleration. Most structures are expected to deform beyond the limit of linearly elastic behavior when subjected to strong ground motion. The nonlinear response history analysis(NRHA) among various nonlinear analysis methods is the most accurate to compute seismic performance of structures, but it is time-consuming and necessitate more efforts. The nonlinear approximate methods, which is more practical and reliable tools for predicting seismic behavior of structures, are extensively studied. The uncoupled modal response history analysis(UMRHA) is a method which can find the nonlinear reponse of the structures for ESDF from the pushover curve using NRHA or response spectrum. The direct spectrum analysis(DSA) is approximate nonlinear method to evaluate nonlinear response of structures, without iterative computations, given by the structural linear vibration period and yield strength from the pushover analysis. In this study, the practicality and the reliability of seismic performance of approximate nonlinear methods for incremental dynamic analysis of mixed building structures are to be compared.

• Annals of Rehabilitation Medicine
• /
• v.39 no.6
• /
• pp.957-963
• /
• 2015

Objective To compare the pain-reducing effect of forest bathing alone versus forest bathing in combination with stretching and strengthening exercises in patients with chronic posterior neck pain. Methods Sixty-four subjects with posterior neck pain that had lasted more than 3 months were enrolled. They were randomly divided into a forest bathing alone (FBA) group and a forest bathing with exercise (FBE) group; each group included 32 subjects. All subjects from both groups walked every morning in the forest for about 2 hours for 5 days. In the afternoon, the FBE group did a stretching and strengthening exercise for about 4 hours; the FBA group had free time in the woods. Visual analog scale (VAS) on one day, VAS over the previous week, neck disability index (NDI), EuroQol 5D-3L VAS (EQ VAS) and index (EQ index), McGill pain questionnaire (MPQ), the number of trigger points in the posterior neck region (TRPs), and the range of motion of the cervical spine were evaluated on the first and last day of the program and compared between the two groups. Results The number of TRPs were significantly reduced in the FBE group compared with the FBA group (p=0.013). However, the other scales showed no significant difference between the two groups. Conclusion When patients with chronic posterior neck pain underwent a short-term forest bathing (less than 7 days) program, FBE was more effective in the reduction of the number of TRPs than FBA. However, all other pain measurement scales we evaluated showed no statistically significant difference between the two protocols.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.41 no.5
• /
• pp.513-522
• /
• 2021

A smartphone (SMP) includes a MEMS sensor that can record 3-components motions and has a wireless network device to transmit data in live. These features and relatively low maintenance costs are the advantage of using SMPs as an auxiliary seismic observation network. Currently, 279 SMPs are monitoring seismic motions. In this study, we compare the SMP records with the seismic station (SS) records to validate SMP records. The data used for comparison are records for five earthquakes that occurred in 2019, which are 321 SS data recorded by the Korea Meteorological Administration and the Korea Institute of Geoscience and Mineral Resources and 145 recorded by SMPs. The analysis shows that the event-term corrected average residual of the SMP MEMS sensor records is 0.59 which indicating that the peak horizontal acceleration by SMP is 1.8 factor bigger than the peak ground acceleration by SS. In addition, the residuals tend to decrease as the installation floor of the smartphone MEMS sensor increases, which is the similar trend with response spectra from SS.

• The Journal of Korean Philosophical History
• /
• no.37
• /
• pp.47-70
• /
• 2013

The purpose of this paper is to figure out T'oegye's philosophy and its characteristics in comparison with Zhuzi's. T'oegye is well-known as the representative of Neo-confucianism in Korea. But his posterior scholars and even contemporary scholars have various viewpoints about his philosophy. So they give him some different evaluation. After Zhuzi's death 300 years later, T'oegye has accepted Zhuzi's philopophical thoughts. In addition, he has added his own philosophical insights on them. First, he indicates concretely the metaphysical activity of li through lidong that Zhuzi has mentioned in some measure. Second, under the ontological aspect of li, he explains that Four beginnings come from li. It implies that li manifests and qi follows. Finally he points out lidao--i.e. li manifests itself, about wuge in his epistemology. Here we can say that whatever his metaphysics/the theory of mind and heart, and epistemology, the whole system of T'oegye's philosophy has its theoretical coherence. He has succeeded Zhuzi's philopophical thoughts thoroughly and furthermore developed Neo-confucian theory in East Asia that has not made before.