• Journal of Dental Rehabilitation and Applied Science
• /
• v.34 no.2
• /
• pp.72-79
• /
• 2018

Purpose: The purpose of this study was to compare flexural strength and elastic modulus of several splinting materials dependent on water absorption. Materials and Methods: Three different materials; LightFix, G-FIX, G-aenial Universal Flo; were used in this study. Thirty rectangular bar specimens ($25{\times}2{\times}2mm$) of each materials were prepared. Fifteen specimens of each materials were stored in 100% relative humidity atmosphere, $37^{\circ}C$ for 24 hours. The other specimens were stored in distilled water, $37^{\circ}C$ for 30 days. Flexural strength and elastic modulus were calculated using Universal testing machine. One-way ANOVA and Scheffe's post hoc test at 95% level of significance were used on all test results. Results: In LightFix, flexural strength and elastic modulus were significantly decreased after aging. In G-FIX, there was no significant change in flexural strength and elastic modulus after aging. In G-aenial Universal Flo, flexural strength was significantly decreased, but elastic modulus did not change significantly. Statistical analysis reveals that flexural strength and elastic modulus increased in the order of LightFix, G-FIX, G-aenial Flo in both 24 hours and 30 days. Conclusion: It could be deduced from this study that flexural strength and elastic modulus of some resins could be changed when it aged in oral environment. Thus this should be considered when choosing a resin to perform a resin-bonded splint.

• Journal of Korean Society of Forest Science
• /
• v.6 no.1
• /
• pp.27-31
• /
• 1967

The bamboo is a plant whose culm grows straight up. This growing characteristics has been widely utilized in industry and craft. But the developments of handcraft making and horticultural techniques in recent years become to demand the bent bamboo culms. This study has been conducted at the experimental grove located at Hyunnae Ri, Okkye Myun, Myungju Gun, Kangwon Do since 1960. Although it has been known that the secret for which bamboo shoots complet growth within 40 odd days lies in their rhizomes, this writer felt the bamboo culm sheath might be another factor in addition. Hence some were stripped of sheath in this bending study as the following: 1. Time of sheath stripping. 2. Direction of sheath stripped for arbitrary bending. 3. Accuracy of bending following the size (growth) of bamboo shoots. The following results were obtained: 1. Bamboo shoots begin to appear in April. But the bamboo shot up in June showed the best bending result with 68% of bending efficiency. 2. Bending of the culm was facilitated by stripping off the sheath located on the side of the direction toward which bending was desired. By doing this, the culm could be bent as much as 90 degrees. But the culm totally stripped of sheath could be bent in any direction. 3. In order to determine the accuracy of bending of bamboo shoots growing, sheath were stripped off the shoots of which height ranged from 10 centimeter to 150 centimeters. The shoots with height of 110 centimeters showed the best result with 90%.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.11
• /
• pp.319-325
• /
• 2018

The use of 3D printing (Additive Manufacturing) technology has expanded from initial model production to the mass production of parts in the industrial field based on the continuous research and development of materials and process technology. As a representative polymer material for 3D printing, the polyamide-based material, which is one of the high-strength engineering plastics, is used mainly for manufacturing parts for automobiles because of its light weight and durability. In this study, the specimens were fabricated using Selective Laser Sintering, which has excellent mechanical properties, and the flexural characteristics were analyzed according to the temperature of the two types of polyamide 12 and glass bead reinforced PA12 materials. The test specimens were prepared in the directions of $0^{\circ}$, $45^{\circ}$, and $90^{\circ}$ based on the work platform, and then subjected to a flexural test in three test temperature environments of $-25^{\circ}C$, $25^{\circ}C$, and $60^{\circ}C$. As a result, PA12 had the maximum flexural strength in the direction of $90^{\circ}$ at $-25^{\circ}C$ and $0^{\circ}$ at $25^{\circ}C$ and $60^{\circ}C$. The glass bead-reinforced PA12 exhibited maximum flexural strength values at all test temperatures in the $0^{\circ}$ fabrication direction. The tendency of the flexural strength changes of the two materials was different due to the influence of the plane direction of the lamination layer depending on the type of stress generated in the bending test.

• Journal of the Korean Society of Radiology
• /
• v.8 no.2
• /
• pp.57-63
• /
• 2014

This study aims to find out the standardized test criteria regarding patients with the anterior cruciate ligament damage by identifying the degree of the flexion gap of femur and tibia upon bending of the anterior cruciate ligament in order to carry out the accurate test of such impairment. On the standardized test method and judgement criteria upon the anterior cruciate ligament test using Telos, it has been shown that there was no significant difference in the results according to the position of a fixed roller in the anterior cruciate ligament test for normal patients. However, in a test for patients who had undergone the anterior cruciate ligament reconstruction, it has been shown that the measured values of the anterior cruciate ligament tended to be pushed when the position of a fixed roller was less than 1cm in the test according to the position of a fixed roller of Telos (less than 1cm, more than 3cm), and this was statistically significant. The anterior cruciate ligament test (knee stress test) is a limited method used in orthopedics and rehabilitation medicine, and there have been no standardized test guidelines available yet although numerous ligament measurement tests have been performed. In addition, since the measured values are often different depending on testers even on the test that is expected to give the same result, the reproducibility of the test is still low. Accordingly, it is considered that the criteria for the anterior cruciate ligament test need to be established, and this would contribute to the accuracy of the diagnosis through the accurate test and standardized measurements.

• Korean Journal of Applied Biomechanics
• /
• v.19 no.3
• /
• pp.435-448
• /
• 2009

The purpose of this study was to investigate the kinemaitc gait parameter of lower extremities with different gait conditions(level walking, stairs, ramp) in old adults. Fourteen healthy older adults participated in this study and kinematic data were measured using 3D motion analysis system(Vicon, Oxford Metrics, England). Statistical analysis was used one-way ANOVA to know the difference of lower extremities angle at each gait phase with a different gait conditions. In sagittal plane, pelvic anterior tilt increased in stairs and ramp climbing and hip and knee flexion increased in stairs climbing but ankle dorsiflexion increased in ramp climbing. In frontal plane, pelvic was up in stairs and hip abduction and adduction more changed in stairs climbing than level walking. Knee varus and ankle inversion increased in stair climbing. In horizontal plane, pelvic internal rotation increased in stairs and ramp climbing and knee internal rotation increased in stairs climbing but ankle external rotation increased in stairs climbing. This results was shown that the stairs and ramp climbing changed the kinematic gait parameters of lower extremities in healthy old adults.

• 한국체육학회지인문사회과학편
• /
• v.54 no.5
• /
• pp.829-840
• /
• 2015

The purpose of this study was to investigated into the kinematics and ground reaction force for gait on induced stereoacuity in normal subjects with normal sight. Eighteen subjects who passed the stereoacuity testing were participated in the experiment(age: 22.1±2.7 years, height: 176.8±4.4 cm, weight: 67.6±5.8 kg). The study method adopted 3D analysis with six cameras and ground reaction force with two force-plates. The results were as follows; In gait velocity, obstacle crossing gait was slower than flat gait. In angular displacement of hip joint, mostly obstacle crossing gait was more flexed than flat gait. In angular displacement of knee joint, obstacle crossing gait was more flexed than flat gait, and stereoacuity reduction gait in TO and FC2 were more flexed than normal vision gait. In angular displacement of ankle joint, obstacle crossing gait in FC2 was more flexed than flat gait. In trunk tilt, obstacle crossing gait in MSt, TO and MSw were more extended than flat gait. In GRF, there was no significant in Fx, obstacle crossing gait in right and left foot were bigger propulsion force than flat gait, obstacle crossing gait in right and left foot were bigger braking force than normal vision gait in Fy, and obstacle crossing gait in right and left foot were bigger than flat gait in peak F1 and peak F2 of Fz, and stereoacuity reduction gait in right foot was lower than normal vision gait in valley force of Fz.

• Polymer(Korea)
• /
• v.24 no.6
• /
• pp.770-776
• /
• 2000

The effect of unreactive coupling agent on mechanical and thermal properties of talc-filled polypropylene (PP) composites was studied. Stearic and oleic acids were introduced as coupling agents, and tensile, flexural, and impact strength, thermal stability and melting transition temperature were measured and analyzed according to the types and concentration of coupling agents. Tensile and flexural strength were enhanced by introduction of coupling agent and the maximum effect was observed at the concentration of 3 wt% of coupling agent. Tensile and flexural strength of PP treated with oleic acid were higher than those of PP treated with stearic acid. but impact strength vice-versa. The reasons for these results were postulated by analyzing morphologies of talc-filled PP observed by SEM.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.10 no.1
• /
• pp.73-79
• /
• 2016

In this paper a cervical rehabilitation robot for Mckenzie exercises to be effective to neck pain relief is proposed. The robot has two degrees of freedom (DOF) for Lateral flexion and extension, Dorsal and Vental flexion which enable user to perform cervical stretching and isometric exercises for neck muscles. The mechanical parts of the cervical rehabilitation robot can be mounted on a back- or head-rest of chair, and user can perform the Mckenzie exercise with seated. In experiments we measured the range of motion of cervical part, EMG signals from neck muscles and the contact forces of a head bracket fixing the head part of user, and then evaluated their performances. From the experimental results, we showed a feasibility of the cervical rehabilitation robot proposed in this study.

• Korean Journal of Applied Biomechanics
• /
• v.19 no.3
• /
• pp.593-601
• /
• 2009

The goal of this study was to investigate the lower extremity's coordination determined by temporal relations with increasing high-heel (3, 7, 9cm) while walking on a treadmill. Twelve healthy women who walked on a treadmill under three conditionswearing 3cm high-heel shoes, 7cm, and 9cm-while kinematic data were collected using a six-cameras (240Hz) Qualisys ProReflex System. From these data, knee flexion, tibia internal rotation, and foot eversion were calculated in Euler technique and found the time for occurring the maximum angle of these movements. The maximum angle of these movements occurred almost simultaneously in 3cm high-heel walking, but not in 7cm and 9cm. The ratio of time for maximum angle of the foot eversion to tibia internal rotation converged to 1 in 3cm high-heel walking, but were less than 1 in 7cm and 9cm. In conclusion, it was indicated that 3cm high-heel walking had better the lower extremity's coordination compared with 7, 9cm high-heel walking.

• Proceedings of the Optical Society of Korea Conference
• /
• 2000.08a
• /
• pp.128-129
• /
• 2000

3차원 형상측정에서 많이 쓰이고 있는 모아레 간섭계에는 그 setup에 따라 Projection Type과 Shadow Type이 있다. 이러한 모아레 간섭계는 광원과 측정 카메라의 각도에 의해 물체의 형상을 측정하게 된다. 그러나, 이러한 광원과 측정 카메라의 각도에 의해 생겨나는 그림자에 의한 영향 때문에 물체의 형상이 굴곡이 심한 곳은 측정하기 어렵다. 본 논문에서는 아래 그림과 같이 두 개 이상의 광원을 사용하여 그 영향을 줄이기 위한 방법을 제안하였다. 이 방법은 projection type이나 shadow type에서 동일하게 적용 가능할 것으로 예상된다. (중략)