• Journal of Korean Association for Spatial Structures
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• v.20 no.2
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• pp.51-58
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• 2020

Recently, deep learning that is the most popular and effective class of machine learning algorithms is widely applied to various industrial areas. A number of research on various topics about structural engineering was performed by using artificial neural networks, such as structural design optimization, vibration control and system identification etc. When nonlinear semi-active structural control devices are applied to building structure, a lot of computational effort is required to predict dynamic structural responses of finite element method (FEM) model for development of control algorithm. To solve this problem, an artificial neural network model was developed in this study. Among various deep learning algorithms, a recurrent neural network (RNN) was used to make the time history response prediction model. An RNN can retain state from one iteration to the next by using its own output as input for the next step. An eleven-story building structure with semi-active tuned mass damper (TMD) was used as an example structure. The semi-active TMD was composed of magnetorheological damper. Five historical earthquakes and five artificial ground motions were used as ground excitations for training of an RNN model. Another artificial ground motion that was not used for training was used for verification of the developed RNN model. Parametric studies on various hyper-parameters including number of hidden layers, sequence length, number of LSTM cells, etc. After appropriate training iteration of the RNN model with proper hyper-parameters, the RNN model for prediction of seismic responses of the building structure with semi-active TMD was developed. The developed RNN model can effectively provide very accurate seismic responses compared to the FEM model.

• Earthquakes and Structures
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• v.8 no.4
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• pp.889-913
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• 2015

Structural vibration characteristics of a semi-active base-isolated building were investigated using seismic observation records including those of the 2011 Great East Japan earthquake (Tohoku earthquake). Three different types of analyses were conducted. First, we investigated the long-term changes in the natural frequencies and damping factors by using an ARX model and confirmed that the natural frequency of the superstructure decreased slightly after the main shock of the Tohoku earthquake. Second, we investigated short-term changes in the natural frequencies and damping factors during the main shock by using the N4SID method and observed different transition characteristics between the first and second modes. In the second mode, in which the superstructure response is most significant, the natural frequency changed depending on the response amplitude. In addition, at the beginning of the ground motion, the identified first natural frequency was high possibly as a result of sliding friction. Third, we compared the natural frequencies and damping factors between the conditions of a properly functional semi-active control system and a nonfunctional system, by using the records of the aftershocks of the Tohoku earthquake. However, we could not detect major differences because the response was probably influenced by sliding friction, which had a more significant effect on damping characteristics than did the semi-active dampers.

• Physical Therapy Korea
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• v.28 no.1
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• pp.47-52
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• 2021

Background: Compared with normal people, stroke patients have decreased voluntary craniocervical motion, which affects their balance. Objects: This study was conducted in order to examine the effects of active craniocervical movement training using a cognitive game on stroke patient's cervical movement control ability, balance, and functional mobility. Methods: The subject of this study were 29chronic stroke patients who were randomly allocated to either an experimental, cognitive game group (n = 15), or control group (n = 14), to which only neuro-developmental treatment (NDT) was applied. The intervention was conducted 5 times per week, 30 minutes per each time, for a total of 4 weeks. Active angle reproduction test, static stability test, limits of stability test, and Time up and Go (TUG) test, respectively, were carried out in order to evaluate cervical movement control ability, static balance, dynamic balance, and functional mobility. Paired t-test was used in order to compare differences between prior to after the intervention, along with an independent-test in order to compare prior to and after-intervention differences between the two groups. Results: After the craniocervical training with a body-driven cognitive game, the experimental group showed significant differences in flexion, extension, and lateral flexion on the affected side, and rotation on the affected side in the active angle reproduction test. The experimental group indicated significant differences in sway length both with eyes-open and with eyesclosed in the static stability test and in limits of stability test and TUG test. The control group to which NDT was applied had significant differences in flexion in the active angle reproduction test and in limits of stability test and TUG test. Conclusion: The above results mean that craniocervical training using a body-driven cognitive game positively influences stroke patient's cervical movement control ability and as a result their balance and functional mobility.

• Journal of Acupuncture Research
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• v.22 no.4
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• pp.1-12
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• 2005

Objectives : The Purpose of this study is to report in patient with common peroneal nerve palsy, who improved by oriental medical treatament. Methods : We Checked the temperature of a leg by Digital Infrared Thermal Imaging(DITI) at intervals of 10 days, angle of active dorsiflexion and range of active motion for estimating the improvement of symptoms. We used the Visual Analogue Scale(VAS) for estimating the degree of pain, too. Results : After 4 weeks treatment, the movement and power of ankle joint improved to nearly normal range. The degree of active dorsiflexion of the ankle increased from $-40^{\circ}\;to\;15^{\circ}$ and range of active motion increased from Gr III to Gr I. The difference of temperature between the both legs decreased remarkably. Conclusion : In this case we experienced improvement of symptoms by conservative oriental medical therapy, e.g acupuncture stimulation, herbal medication, physical therapy. It should be needed further investigation on common peroneal nerve palsy and its symptoms in order to set up a reasonable standard about a surgical operation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.6
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• pp.366-371
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• 2017

In this paper, we introduce an electrocardiogram (ECG) system designed to solve problems caused by wetgels and motion artifacts in measuring active movement. The system is called a dry-contact ECG and was designed by considering impedance matching between skin and electrode as well as the frictional electricity between electrode and clothes. In order to create the system, we measured impedance on the skin-electrode interface, and the result was applied to the electronic circuit scheme. Moreover, we added an electrode on the back of the measurement electrode to make a flow path to ground the electrical noise. The final ECG circuit and novel electrode were used to detect real human cardiac signals from a subject who was tested while standing still and walking. The signals obtained from the two activities were nicely shaped, without any motion artifact noise. We took electrode size into account in this study because the impedance depended on the area of the electrode. An electrode of 50 mm diameter showed the best curve for the ECG signal without any electrical noise.

• Physical Therapy Rehabilitation Science
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• v.4 no.2
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• pp.66-72
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• 2015

Objective: The aim of this study was to investigate the effect of balance training with plantar flexor stretching on ankle dorsi flexion range of motion (ROM), balance, and gait ability in stroke patients. Design: A randomized controlled pilot trial. Methods: Thirty stroke patients volunteered to participate in this study. The subjects were randomly allocated to two groups: the experimental group (n=15) received the neurodevelopment therapy plus balance training with plantar flexor stretching for 20 minutes in one session. The control group (n=15) received the same neurodevelopment therapy plus plantar flexor static stretching for 20 minutes in one session. Both groups underwent sessions four times a week, for a total of 4 weeks. Measurements included passive range of motion (PROM), active range of motion (AROM) of ankle dorsiflexion using a goniometer, timed up and go (TUG), the functional reaching test (FRT), and the 10 m walk test (10 MWT). Results: There were significant improvements in AROM and PROM of ankle dorsiflexion, TUG, and FRT scores after the intervention in the experimental group (p<0.05). However, the control group showed no statistically significant differences except for PROM of ankle dorsiflexion. The experimental group showed a significant improvement in PROM, TUG, and FRT scores compared to the control group (p<0.05). Conclusions: Balance training with plantar flexor stretching improves ankle dorsiflexion ROM and balance ability in patients with stroke. Therefore, this therapeutic intervention will be effective for rehabilitation of stroke patients in the clinical setting.

• Journal of Korean Foot and Ankle Society
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• v.21 no.4
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• pp.151-155
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• 2017

Purpose: Reducing tenderness or pain on the ankle joint and improving the range of motion are thought to be possible using hyaluronate-based anti-adhesive agents. On the other hand, there are more aspects to be studied regarding the incidence of complications, such as resting pain, tenderness, and stiffness, after surgery. Therefore, the aim of this study was to prove the effectiveness of the agents after ankle fracture surgery. Materials and Methods: Patients, who underwent open reduction and internal fixation surgery due to ankle joint fractures from June 2015 to May 2016, were studied prospectively. Thirty patients of them received a $Guardix^{(R)}$ injection during their surgeries and were included in the injection group. The other 30 patients were included in the control group. Postoperatively, tenderness on the scar, a delay in wound healing, and the active range of motion were evaluated at 2, 6, and 12 weeks after surgery. Results: A significant difference in tenderness on the scar was observed 2 weeks after surgery. On the other hand, there was no significant difference at 6 and 12 weeks after the surgery. The agent-using group showed a 6.7% delay in wound healing and a 93.3% nondelaying. In the non-using group, the delay was 63.3%, while non-delay was 36.7% (p<0.001). The group that underwent $Guardix^{(R)}$ usage showed an effective result in the visual analogue scale, which was statistically significant (p<0.001). The result at 6 and 12 weeks after surgery showed a significant difference. Conclusion: Improvement was observed in the patients who underwent a $Guardix^{(R)}$ injection, regarding the range of motion, visual analog scale, and healing of the wound postoperatively.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.3
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• pp.26-37
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• 1998

In this study, the motion control techniques allied to the test ship NARAE are summarized and the results of sea trials are resented. NARAE adopted a hybrid hull form with lower hull and submerged foils. This type of ship has a substantial instability in heave, pitch and roll modes at the foil-borne stage due to little restoring force, so an active control is indispensable to keep the stability. 4-hydraulic actuators with servo valves were installed to drive foils, and several sensors were used to measure the motion of the ship. PID controller was adopted as a motion controller, and for the real-time control, Pentium-class industrial PC was used. Sea trials including take-off, landing, and banked turn maneuvering were carried out for a period of over 3 months and quite satisfactory results were obtained.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.2
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• pp.17-25
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• 2006

In the present study, a 2-D chimera technique for overlapped bodies in relative motion is developed using unstructured triangular meshes. The solid boundary nodes located next to the intersecting point between bodies are merged to the intersecting point to assure accurate representation of the intersecting region. In order to assign proper value of flow variables at the nodes located out of the computational field, interpolation is conducted for non-active nodes. For validation, the motions of a NACA64A006 airfoil and a NACA0012 airfoil with a plane flap are computed and the results are compared with other simulations. The motion of a launching missile ejected from a NACA0012 airfoil is also simulated.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.18 no.1
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• pp.83-86
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• 2012

Background: The research examined the effect of a scapular stabilizing exercise on shoulder pain, active range of motion (AROM) and changes in the position of the shoulder blade of patients with frozen shoulder. Methods: General physical therapy and a scapular stabilizing exercise were applied to a 53-year-old female patient with frozen shoulder three times a week for four weeks. Before and after the therapy, measurements were made on the visual analog scale (VAS) and of the AROM, and a lateral scapular slide test was conducted. Results: Following the therapy, VAS fell from 7 to 3. Before therapy, flexion, abduction, internal rotation, and external rotation recorded $133^{\circ}$, $102^{\circ}$, $45^{\circ}$, and $53^{\circ}$ respectively; after the therapy they increased to $150^{\circ}$, $123^{\circ}$, $55^{\circ}$, and $65^{\circ}$ respectively. The lateral scapular slide test showed sliding distances before therapy of 8.5cm at $0^{\circ}$, 9.2cm at $45^{\circ}$, and 11.3cm at $90^{\circ}$; after therapy, the distances decreased to 6.8 cm at $0^{\circ}$, 8.2 cm at $45^{\circ}$, and 9cm at $90^{\circ}$. Conclusion: The scapular stabilizing exercise was effective in alleviating shoulder pain, increasing AROM, and reducing changes in the position of the shoulder blade of frozen shoulder patients.