• 한국전문물리치료학회지
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• 제19권2호
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• pp.80-86
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• 2012

The purpose of this study was to compare the muscle activity of the abdominal and lumbar multifidus during unilateral prone hip extension on the floor and on a round foam roll. Fifteen healthy participants were recruited. They were instructed to perform a unilateral hip extension on the floor and on a round foam roll in the prone position. Surface electromyography (EMG) signals were recorded from bilateral lumbar multifidus (LM), external oblique (EO), and internal oblique (IO) muscles. A paired t-test was used to compare muscle activity, with the level of significance set at ${\alpha}$=.05. The results showed that bilateral LM, EO, IO EMG activity during right-hip extension on a round foam roll was greater than that on the floor, and EMG activity of bilateral LM, right EO, and left IO during left-hip extension on a round foam roll was greater than that on the floor (p<.05). These findings suggest that the unilateral hip-extension exercise on a round foam roll can be used to activate the lumbar multifidus and abdominal oblique muscles and causes a different increasing pattern between the two lifting sides.

• 공업화학
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• 제33권6호
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• pp.613-617
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• 2022

미세먼지 다량배출사업장의 미세먼지를 제거하는 백하우스의 백필터 여과체를 제작하기 위한 대면적 PTFE 나노섬유 제조 장치를 설계하여 제작하였다. 상용 PTFE 폼 필터의 미세먼지 여과효율을 높이기 위해 전기방사 공정과 열처리 공정을 이용하여 PTFE 나노섬유를 코팅하였다. PTFE 나노섬유를 대면적의 PTFE 폼 필터 표면에 연속적으로 코팅하기 위하여 roll-to-roll 공정용 장비와 제조 공정을 제안하였다. PTFE 나노섬유를 연속적으로 제작하기 위해 전기방사부와 열처리부를 roll-to-roll 공정에 맞게 장비를 최적화하여 설계하고 제작하였다. 본 장비를 이용하여 대면적 필터 여과체를 제조하고, 제조된 여과체의 표면 형태, 조성, 필터 특성을 확인하였다. 롤 형태의 대면적 여과체 전반에 걸쳐 PTFE 나노섬유가 균일하게 코팅되었고, 본 여과체는 280 ℃에서도 280 ℃에서도 PM_2.5 기준 91.79%의 높은 집진효율과 1 m/min 기준 62 Pa의 우수한 압력 손실 특성을 보였다.

• 한국전문물리치료학회지
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• 제17권4호
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• pp.16-25
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• 2010

The aim of this study was to determine the muscle activity of the abdominalis and erector spinae during bridging and unilateral bridging exercises on the firm surface, the sir-fit, and the foam roll. Eighteen healthy young subjects were recruited for this study. Surface electromyographic (EMG) activities were recorded from the both sides of the rectus abdominalis, external obliques, internal obliques, and erector spinae muscles during bridging and unilateral bridging-exercises. A one-way repeated analysis of variance was used to compare the EMG activity of each muscle according to the support surface condition. Differences in the EMG activities between the bridging and unilateral bridging exercises, and between the right and left side were assessed using a paired t-test. The study showed that the EMG activities of all of the muscles were significantly higher when the bridging exercise was performed using the foam roll or sit-fit than on the firm surface. The EMG activities of the right rectus abdominis, right external obliques, the right internal oblique, and both erector spinae were significantly higher during unilateral bridging ex exercise using the foam roll or the sit-fit than on the firm surface. The EMG activities of all of the muscles were significantly higher during the unilateral bridging exercise than during the bridging exercise. Based on these finding, performing the unilateral bridging exercise using the sit-fit or the foam roll is a useful method for facilitating trunk muscle strength and lumbar stability.

• 한국전문물리치료학회지
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• 제13권3호
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• pp.102-110
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• 2006

To improve trunk stability, various exercise protocols were introduced into the clinical field. Trunk and lumbar stability exercises on unstable surfaces are especially recommended to improve lumbar stability. The purpose of this study was to compare abdominal oblique muscle activity during leg raising in hook-lying position among 3 different type of surface conditions (on floor (F), vestibular board (VB), and foam roll (FR)). Sixteen able-bodied volunteers, who had no medical history of lower extremity or lumbar spine disease, were recruited for this study. Surface electromyography (EMG) activity was recorded from the internal and external oblique muscles of both sides. The normalized EMG activity was compared using a one-way repeated ANOVA. The results showed that the EMG activities of the internal oblique and external oblique of the lifted leg side during straight leg raising significantly increased under the FR condition when compared to the F condition. There was no significant difference of the EMG activity in abdominal oblique muscles between the VB and the FR conditions. The EMG activity of the internal oblique of supported leg side during the straight leg raising was significantly greater under the FR condition than the VB and F conditions (p<.05). The composition ratio of EMG activity of internal oblique muscles during straight leg raising was significantly increased under the FR condition. Therefore, straight leg raising exercise on foam roll in hook lying position could be beneficial to improve trunk and lumbar stability.

• 한국운동역학회지
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• 제12권1호
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• pp.89-114
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• 2002

The purpose of this study was to analyze impact absorption function of midsole in cushioned marathon shoes. The foot is made up of a complex interaction of bones, ligaments, and muscles. These structures help the foot alternate between being a mobile, flexible adaptor and a stable rigid lever. The foot is broken down into two functional parts, the forefoot and the rearfoot. Cushioned marathon shoes for high arches have generous cushioning for efficient and high-mileage runners. Cushioned marathon shoes are made for feet that have high arches or no excessive motion and don't roll inward or roll outward. This condition is known as underpronation. Especially, Cushioned marathon shoes are designed to reduce shock and generally have the softest (or most cushioned) midsoles and the least medial support. They are usually built on a semicurved or curved last to encourage foot motion, which is helpful for underpronators (who have rigid, immobile feet). Cushioning marathon shoes recommended for the high-arched runner, whose foot may roll outward (supinate) rather than the natural slight inward roll, or whose feet may be relatively rigid. Cushioning shoes emphasize flexibility and usually are built on a curved or semicurved last to encourage a normal motion of the foot. Cushioning shoes usually offer no medial (inner foot) support. Cushioned marathon shoes have the single-density midsole, which is stable and relatively firm for a cushioned shoe, stays the same. But the forefoot is more rounded, and the rearfoot now includes a new and supportive rearfoot cradle. A foam midsole, perhaps with layers of different densities, to provide cushioning and shock absorption. EVA (ethylene vinyl acetate) and PU (polyurethane), the materials from which these foams usually are made. EVA is slightly softer than PU. EVA and PU may be layered together in a shoe, or a shoe may have more than one density of EVA.

• Elastomers and Composites
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• 제50권1호
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• pp.13-17
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• 2015

A study of the effects of MWCNT as a nucleating agent on the formation reactions of the rigid polyurethane foams (RPUFs) was carried out. Sample PUFs, formulated with grease-type master batch of MWCNT/surfactant, were fabricated by free-rising method. Temperature changes with time during foaming process were measured using a digital thermometer. RPUF foaming process was observed to undergo 2-step processes with temperature inflection around 60 sec after the start of reaction, and then reached slowly the max. temperature. While the max. temperature of neat PUF was measured as ca. $120^{\circ}C$, that of the samples with MWCNT were as higher value as ca. $130^{\circ}C$, and, even the time to reach that temperature was reduced by about 15 sec. Average cell size of PUF samples decreased from 185.1 for the neat PUF to $162.9{\mu}m$ for the sample of 0.01 phr of MWCNT. As the result, it was considered that MWCNT in RPUF foaming process could play a roll both as a nucleating agent and as a catalyst.

• 한국산학기술학회논문지
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• 제9권6호
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• pp.1775-1781
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• 2008

가교제의 종류가 헬리콥터 연료탱크의 자기밀폐층 소재로 적용시키기 위한 천연고무 스폰지의 팽윤에 미치는 효과를 조사하였다. 과산화물과 황을 섞은 가교방식과 과산화물에 의한 가교방식을 채택하였다. 천연고무 콤파운드를 Kneader와 Roll-Mill을 활용하여 제조하고, 고압조건의 프레스에서 부분 가교시킨 후 대기압의 금형에서 발포와 완전가교를 실시하였다. 얻어진 스폰지의 겉보기밀도를 측정하고 스폰지의 셀구조를 주사전자현미경을 통하여 관찰하였다. 톨루엔, 이소옥탄과 항공유를 사용하여 실온에서 팽윤실험을 실시하였다. 용매에 2분 동안 침적 후 얻어지는 부피팽윤비 값은 과산화물 가교에 의한 천연고무 스폰지가 비슷한 양의 황과 과산화물의 혼합가교에 의한 경우보다 높았다. 스폰지의 겉보기밀도와 셀구조는 과산화물 함량에 매우 민감하였으며 이는 또한 천연고무 스폰지의 팽윤거동에 영향을 미쳤다. 천연고무 스폰지가 연료와 접촉하여 신속한 팽윤이 얻어지기 위하여 금형에서 동시에 발생하는 두 가지 반응인 발포제의 분해반응과 천연고무의 가교반응을 적절히 조절하는 것이 중요하다.

• 대한물리의학회지
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• 제9권4호
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• pp.455-463
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• 2014

PURPOSE: The purpose of this study was to compare the effects of Graston and self-myofascial release (SMR) techniques on knee joint flexibility, hamstring, and quadriceps strength. METHODS: Twenty subjects with hamstring shortness participated in this study. The subjects were assigned randomly to one of two groups: The Graston technique (GT) group received intervention using a Graston instrument for one minute, and the SMR group performed self-exercises using a foam roll for one minute. The range of motion (ROM) of the knee joint was measured by active knee extension test, and a handheld dynamometer was utilized to collect the hamstring and quadriceps muscle strength. This experiment was performed by two physical therapists. The significant level was set at ${\alpha}$=0.05. RESULTS: The results were as follows: 1) The ROM of the knee joint and quadriceps muscle strength were significantly increased in both groups. 2) Hamstring muscle strength was significantly reduced in both groups. 3) There were no significant differences between the GT group and SMR group for any variable. CONCLUSION: The results of this study suggest that SMR is an effective and easy technique for restoring proper muscle length and strength in subjects with hamstring shortness. We recommend that SMR technique be used for treat hamstring shortness in clinical setting and home-program.

• 대한물리의학회지
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• 제11권1호
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• pp.1-9
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• 2016

PURPOSE: This study compared the effectiveness of trunk control exercise performed on an unstable surface with that of general balance exercise on dynamic balance in the patients with chronic stroke. METHODS: The persons of this study were thirty-seven chronic stroke patients were recruited and randomly divided into 2 groups; (1) those who performed trunk control exercise on a foam roll and (2) those who performed general balance exercise. The exercises were performed 5 times a week for 4 weeks. To determine the effectiveness of the 2 types of exercises, we measured dynamic balance at the beginning of the exercises and again after 4 weeks at the completion of exercises program. RESULTS: After 4 weeks of exercise, both the groups showed increased Berg's balance scale and timed-up-and-go test (p<.001) scores. However, Trunk control exercise group was more effective than general balance exercise group was in increasing the Berg's balance scale (p<.01) and timed-up-and-go test (p<.05) scores. CONCLUSION: We suggest that trunk control exercise may be effective in increasing the balance ability of patients with chronic stroke than general balance exercise. Thus, trunk control exercise is important for such patients. Further studies are needed for better understanding of the effectiveness of trunk control exercise in chronic stroke patients.

• 폴리머
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• 제27권5호
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• pp.436-442
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• 2003

에틸렌-프로필렌 디엔 고무 (EPDM)와 같은 열경화성 탄성체는 자동차의 스폰지 웨더스트립 (sponge weatherstrip)에 적용되는 주 재료이다. 그러나 열경화성 탄성체의 특성 때문에 환경적인 문제가 야기된다. 더구나 EPDM 재료의 weatherstrip 제조 시 배합, 가류와 같은 여러 생산 공정을 거쳐야 함으로 생산 단계별 품질산포가 크고 제품의 형상 유지가 어려워 품질의 안정성이 떨어진다. 따라서 재활용과 획기적인 제조기술 그리고 수발포를 할 수 있는 새로운 열가소성 가황체 (TPV)재료 개발로 종래의 EPDM 웨드스트립 제조 문제들을 개선이 필요하게 되었다. 본 연구에서는 TPV 수발포 공정에서의 발포체의 밀도와 구조적인 면을 물의 양과 발포 온도 등의 가공 조건들의 영향을 수행하여 TPV가 수발포로서 균일한 발포체를 얻을 수 있다는 것을 알 수 있었다. 연구결과 EPDM 웨더스트립의 많은 재활용이 곤란한 문제점 등을 해결할 수 있고, 이 새로운 발포 기술은 고무산업에 돌파구를 만들어 나갈 것으로 기대된다.