• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.219-220
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• 2017

Current domestic waterproofing market in Korea mainly uses single-ply waterproofing materials comprised of coatings or waterproof sheets and two or more-ply composite waterproofing methods. In order to evaluate these types of composite waterproofing systems, a new test equipment and method that incorporates various deterioration conditions (joint displacement, chemical exposure, water pressure etc) was developed. In a comparison testing, the results showed that flexible type materials have higher response performance towards joint displacement than the hardened material. Furthermore, the importance of securing the stability of the waterproofing method in the vulnerable over-lap joint areas of waterproofing sheets is emphasized.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.225-232
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• 2007

This work intends to investigate the effects of shift characteristics on the propulsion performance of a manual wheelchair with an automatic transmission. A planetary gear train is employed to generate a two-stage shift automatically, based on the distance traveled from rest. Motion analysis has been performed for measuring kinematic properties of the arm and then the inverse dynamics has been applied for estimating joint forces/torques. Then, a parametric study has been performed to find a set of the shift ratios and the shift intervals for optimizing propulsion performance. Results show that the propulsion performance is closely related to the shift condition. It is found that a short shift interval is desirable for a short distance propulsion. However, an optimum shift interval for a long distance propulsion is inversely proportional to the shift ratio approximately. Consequently, the automatic transmission can greatly lower the joint loadings by the speed reduction, which eventually contribute to prevent joint injuries of wheelchair users.

• Journal of Welding and Joining
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• v.18 no.2
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• pp.196-196
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• 2000

Formation of the weld defect, such as a blowhole and a pit in lap-jointed fillet arc welds has been a serious problem in arc welding of Zn-coated steel sheet. In this study, the relationship among welding conditions, welding materials and defect formation was investigated in order to minimize these defects in the CO₂ welds. In addition, the arc stability of the commercial welding wires was evaluated for revealing their effects on defect formation. Main conclusions obtained are as follows:1) There was no difference between shear tensile strength of the sound welds and that of the welds with blowholes whose diameters are less than 0.5mm. However, the welds with blowholes whose diameters are equal or larger than 0.5mm and pits exhibited tensile strength 10~20% and 30~40% lower than that of the sound welds respectively.2) The optimum welding condition to effectively prevent or reduce the weld defects formation are as follows:- The welding variables of 220A-23V-100cm/min and 120A-190V-30cm/min were recommended for minimizing the weld defects.- The gap between the two sheets at the lap-joint should be controlled to more than 0.2mm- Solid wire was less susceptible to the formation of the weld defects than the flux-cored wire.- The low welding current condition produced less weld defects than the hihg welding current condition.3) One of the reason why the amount of the defect was reduced at the low welding current was the gas discharging by the active agitation of the molten pool, due to an increasing in the number of the short circuit. (Received September 27, 1999)

• Journal of Welding and Joining
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• v.18 no.2
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• pp.69-76
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• 2000

Formation of the weld defect, such as a blowhole and a pit in lap-jointed fillet arc welds has been a serious problem in arc welding Zn-coated steel sheet. In this study, the relationship among welding conditions, welding materials and defect formation was investigated in order to minimize these defects in the CO₂welds. In addition, the arc stability of the commercial welding wires was evaluated for revealing their effects on defect formation. Main conclusions obtained are as follows: 1) There was no difference between shear tensile strength of the sound welds and that of the welds with blowholes whose diameters are less than 0.5mm. However, the welds with blowholes whose diameters are equal or large than 0.5mm and pits exhibited tensile strength 10∼ 20% and 30∼40% lower than that of the sound welds respectively. 2) The optimum welding condition to effectively prevent or reduce the weld defects formation are as follows: -The welding variables of 220A-23V-100cm/min and 120A-19V-30cm/min were recommended for minimizing the weld defects. -The gap between the two sheets at the lap-joint should be controlled to more than 0.2mm. -Solid wire was less susceptible to the formation of the weld defects than the flux-cored wire. -The low welding current condition produced less weld defects than the high welding current condition. 3) One of the reason why the amount of the defect was reduced at the low welding current was the gas discharging by the active agitation of the molten pool, due to an increasing in the number of the short circuit.

• Physical Therapy Rehabilitation Science
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• v.13 no.2
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• pp.152-162
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• 2024

Objective: This study was conducted to analyze the effect of wearable Electromyography-controlled functional electrical stimulation (EMG-controlled FES) System on Gait Function and cardiopulmonary metabolic efficiency during walking in older adults. Design: Cross-section study Methods: Total 22 older adult participants suitable to selection criteria of this study participated in this study. The EMG-controlled FES System, which functions as a wearable physical activity assist FES system was used. All participations performed randomly assigned two conditions (Non-FES assist [NFA], FES assist [FA]) of walking. In all conditions, spatio-temporal parameters and kinematics and kinetics parameters during walking was collected via 3D motion capture system and 6 minutes walking test (6MWT) and metabolic cost during walking and stairs climbing was collected via a portable metabolic device (COSMED K5, COSMED Srl, Roma, Italy). Results: In Spatio-temporal parameters aspects, The EMG-controlled FES system significantly improved gait functions measurements of older adults with sarcopenia at walking in comparison to the NFA condition (P<0.05). Hip, knee and ankle joint range of motion increased at walking in FA condition compared to the NFA condition (P<0.05). In the FA condition, moment and ground reaction force was changed like normal gait during walking of older adults in comparison to the NFA condition (P<0.05). The EMG-controlled FES system significantly reduced net cardiopulmonary metabolic energy cost, net energy expenditure measurement at stairs climbing (P<0.05). Conclusions: This study demonstrated that EMG-controlled FES is a potentially useful gait-assist system for improving gait function by making joint range of motion and moment properly.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1967-1974
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• 1991

When the functional electrical stimulation is employed to recover mobility to the plegic, it is very important to understand functions of the selected muscles. I have investigated how a muscle acts to accelerate the body segments, since the body segements are connected by joints so that contraction of a muscle not only rotates the segments to which it is attached but also causes other segments to rotate by creation a reaction force at every joint, which is called the inertial coupling. I found that a single-joint muscle always acts to accelerate the spanned joint in the same direction as the joint torque produced by the muscle. However, a double-joint muscle can act to accelerate the spanned joint in the opposite direction to the joint torque produced by the muscle depending on (1) the body position, (2) the body-segmental parameters, and (3) the type of the movement. Investigating the condition number of the inertia matrix of the body-segmental model gave us some insights into how controllable the body-segmental system is for different values of the factors mentioned above. The results suggested that the upright position is the most undesirable position to independently control the three segments(trunk, thigh and shank) and that the controllability is the most sensitive to variation of the shank length and the trunk mass, which implies that accuracy is required particularly when we estimate these two body-segmental parameters before the paralyzed muscles are innervated by using electrical stimulation.

• Explosives and Blasting
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• v.36 no.3
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• pp.1-9
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• 2018

This study was conducted to evaluate the influences of the angle of artificial joints, the distance between the artificial joints and the blast hole, and the number of artificial joints on the pressure wave propagation, crack propagation, and blast wave velocity. The evaluation was conducted numerically by use of the Euler-Lagrange solver supported by the AUTODYN, which is a dynamic FEM program. As a result, it was found that the blast wave velocity was decreased most rapidly as either the distance between the artificial joint and the blast hole was decreased or the angle of the artificial joint was increased. In contrast to the case of no artificial joint, the amount of attenuation of the blast wave velocity was considerably large when an artificial joint was present. However, the effect of the number of artificial joint on the attenuation of the blast wave velocity was negligible under the given condition.

• The Korean Journal of Pain
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• v.22 no.3
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• pp.229-233
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• 2009

Background: Sacroiliac (SI) joint pain is a challenging condition that causes lower back or buttock pain; however, there is no universally accepted long-term treatment. There have been several reports of ligament prolotherapy for SI joint pain, but these have had inconsistent results, probably due to the lack of a specific diagnosis for patient selection and variability in the volume, number and sites of injection. Therefore, this study was conducted to assess the efficacy of intraarticular prolotherapy for relieving SI joint pain diagnosed by local anesthetic intraarticular injection. Methods: Twenty-two patients with SI joint pain confirmed by 50% or more improvement in response to local anesthetic block underwent intraarticular prolotherapy with 25% dextrose water every other week three times. The numeric rating scale (NRS) for pain and Oswestry disability index (ODI) were assessed at the initial visit and after completion of a series of prolotherapy and the NRS was checked during monthly follow-up sessions to evaluate the long-term effectiveness of this technique. Results: Twenty patients completed prolotherapy and followed up as scheduled. The NRS and ODI were significantly improved from 6 (4-8) and $34.1{\pm}15.5$ to 1 (0-3) and $12.6{\pm}9.8$ (P < 0.01), respectively, at 1 month after prolotherapy. The mean duration of pain relief of 50% or more was 12.2 months (95% CI, 10.0-14.3) as determined by Kaplan-Meier survival analysis. Conclusions: Intraarticular prolotherapy provided long-term relief of sacroiliac joint pain and may have more benefits than ligament prolotherapy or neurolysis.

• Journal of Korean Foot and Ankle Society
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• v.14 no.2
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• pp.146-150
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• 2010

Purpose: Pilon fracture has several serious complications such as joint stiffness, arthrosis and delayed angular deformity. We report short-term results of new treatment modality using distracted dynamic external fixators and early controlled ankle motion. Materials and Methods: Eight cases of severe pilon fractures for which we tried small plate fixation and additional distracted dynamic external fixators from July 2007 to June 2009 were included. Half passive continuous ankle joint motion was allowed under free hinged ring fixators after the operation. The external fixators were removed after two or three months from the surgery. We investigated joint space by radiograph, joint pain, range of motion, patient's satisfaction of treatment protocol. Results: Joints were distracted when external fixators were applied and mean 28% of space loss developed after removal of external fixators. In most of cases, satisfactory alignments were maintained. Regarding range of joint motion, mean dorsiflexion angle was 15 degrees and mean plantarflexion angle was 32 degree in the condition of wearing external fixators. There was mean 8% reduction of range of motion but no further progression of ankle stiffness after removal of external fixators. Dorsiflexion was not improved after that, but plantarflexion angle was improved 10% even after removal of external fixators. Patients were generally in compliance with the treatment protocols with high level of satisfaction. Conclusion: We got good results with distracted dynamic external fixators and early continuous half-passive joint motion for pilon fractures in terms of joint pain and range of motion. Therefore we suggest this new protocol as an alternative modality for severe pilon fractures.

• Physical Therapy Rehabilitation Science
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• v.5 no.3
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• pp.120-124
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• 2016

Objective: Chronic lateral epicondylitis is a condition which becomes sore and tender on the lateral side of the elbow joint damaged from overuse and repetitive use of the extensor muscles of the forearm. The purpose of this study was to investigate the effects of flexion degrees in the elbow joint on extensor carpi radialis longus and brevis and biceps brachii muscles in individuals with healthy young adults. The main purpose of this study was to suggest the feasibility of optimal elbow angle during therapeutic eccentric exercise with resistance for strengthening of wrist extensors. Design: Cross-sectional study. Methods: Thirty health young adults (male 15, female 15) participated in this study. This study measured muscle activation in four different conditions of elbow flexion, $0^{\circ}$, $30^{\circ}$, $60^{\circ}$, and $90^{\circ}$ during eccentric exercise with weight loading in wrist extensors, extensor carpi radialis longus and brevis and biceps brachii muscles using surface electromyography. Results: The muscle activation of extensor carpi radialis showed a negative relationship with the degrees of elbow joint flexion. With increasing elbow flexion angles, the ECRL muscle activation amount was significantly lower (p<0.05). In contrast, the muscle activation of the ECRB muscle activation amount was significanlty higher (p<0.05). Conclusions: This study suggests that the eccentric exercise of wrist extension with selected activation of wrist extensor muscles according to elbow flexion positions, and suggests that the extensor carpi radialis longus and brevis will need to be strengthened for preventing and treating chronic lateral epicondylitis regardless of degrees of elbow joint flexion.