• Tribology and Lubricants
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• 제31권6호
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• pp.294-301
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• 2015

In this paper, we predict the rotordynamic force coefficients of tilting pad journal bearings (TPJBs) with rocker-back pivots, and we compare the predictions to recently published predictions and test data. The present TPJB model considers the rocker-back pivot stiffness calculated based on the Hertzian contact-stress theory, which is nonlinear with the application of a force . For the five-pad TPJB in load-between-pad and load-on-pad configurations, the predictions show the pressure- and film-thickness distributions, the deflection and stiffness of the individual pivots, and bearing stiffness and damping coefficients. The minimum film thickness and peak pressure occur at the bottom pad on which the applied load is directed. Because of the preload, the pres- sure is positive even at the upper pad in the opposite direction to the applied load. The pivot deflection and stiff- ness are maximum at the bottom pad that receives the heaviest pressure load. The predicted stiffness coefficients increase as the static load and rotor speed increase, while the damping coefficients decrease as the rotor speed increases, but increase as the static load increases. In general, the predicted stiffness coefficients agree well with the test data. The predicted damping coefficients overestimate the test data, particularly for large static loads. In general, the current predictive model considering the pivot stiffness improves the accuracy of the rotordynamic performance compared to previously reported models.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.175-178
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• 1997

A modified Mukerjee's model considering the microstructural evolution was developed to study the superplastic bulge forming process of Ti-6Al-4V alloy. Through the microstructual observation after deformation, it was found that the grain growth rate of uniaxially tested specimens was different from that of biaxially deformed specimens. From this result, bulge forming experiments with and without back pressure were performed to examine the grain growth behavior and to compare the results of biaxial test with those of triaxial test. Good agreement between the prediction by a modified Mukerjee's model and the experimental measurements was obtained for bulge profile and thickness distribution.

• 대한정형도수물리치료학회지
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• 제29권3호
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• pp.73-84
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• 2023

Background: This study aimed to compare pressure pain thresholds (PPTs) in the vertebral segments between patients with chronic lower back pain (CLBP) and healthy participants without back pain and to determine the correlation between vertebral bone-segment PPT and pain level, lower back pain dysfunction, and psychological status in patients with CLBP. Methods: The subjects of this study were 23 healthy adults and 23 adults with CLBP. PPT was measured in 23 spinal bone segments using a PPT device, and the CLBP group was subjected to a pain level test (NRS) and a psychological test using the Korean version of the pain catastrophizing scale (KPCS). The functional level was assessed using the Korean version of the Oswestry disability index (KODI). Results: PPTs of the spinal sclerotomes were significantly lower in patients with CLBP than in healthy participants. In the CLBP group, the composite score of lumbar PPTs showed a high correlation with the composite scores for all segments, but not with the pain level (NRS), KPCS score, and spinal sclerotome PPT. Moreover, PPT in the sacral sclerotomes showed a significant negative correlation coefficient with function, with a KODI score of -.462 (p<.01). Conclusion: In this study, PPTs in all spinal segments in patients with CLBP was significantly lower than that in healthy subjects. The PPTs of the lumbar region was significantly correlated with the PPTs of other spinal regions. Through this study, it was found that there were changes in PPTs in CLBP patients not only in the lumbar region but also in other spinal regions. This information should be considered during clinical treatment of patients with low back pain.

• 한국농공학회지
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• 제13권4호
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• pp.2445-2455
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• 1971

One-dimensional Consolidation tests with pore pressure measurement were caried in the ANTE-US consolidometer in order to investigate the effects of loading conditions on consolidation behavior of the soft clay. Undisturbed specimens of a sensitive clay were loaded in load-increment ratioes 0.5, 1.0 and 2.0, and load increment duration of 1, 6, 12, 24 and 48 hours with the application of 40 psi of back pressure. There is no significant effect of load-increment ratio on compression-pressure relationship, but the test with one-hour load increment duration doesn't represent the same results of the standard consolidation test in the sensitive clay.

• 대한물리치료과학회지
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• 제28권3호
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• pp.66-75
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• 2021

Background: The purpose of this study is to investigate the effect of muscle energy technique and stretching on pain and pressure pain fear-avoidance beliefs questionnaire in patients with chronic back pain aged 30~40 years. Design: Pretest-Posttest design: single blind. Methods: The subjects of this study were 30, 22 males and 8 females between the ages of 30 and 40 with chronic back pain. Each group consists of three groups of 10 people. Changes in back pain were observed using Korean version of Oswestry Disability Index (K-ODI), visual analogue scale (VAS), and fear-avoidance beliefs questionnaire (FABQ). And the change in tenderness was observed using digital pressure statistics. Changes between groups after 3 weeks were compared with those before the experiment using one way ANOVA to determine the changes after 3 weeks. And the change within the group was investigated using the paired t-test. Results: As a result of the experiment, there were significant differences in the group changes in K-ODI, VAS, FABQ, and pressure pain (p<0.05). And there was a significant difference in all items after 3 weeks compared to before the experiment (p<0.05). Conclusion: In patients with chronic back pain, the muscle energy technique and stretching gave a significant difference in pain and pressure pain, fear-avoidance beliefs questionnaire changes. And this result suggests the possibility of providing basic data for future research and clinical physiotherapy intervention.

• 한국의류학회지
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• 제13권2호
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• pp.109-116
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• 1989

Korean clothings are admired for their beauty and traditional value. On the other hand, many of Korean women complain of chest restriction. Korean skirts may give high garment pressure to the wearers because the Korean skirt-band do not resolve physical tensions in size or in stretch. This paper aims at the identification of the garment pressure caused by the Korean skirt-band and the cardiopulmonary change caused by garment pressure. The Korean skirt-band were made in 3 kinds of size, and 21 women were selected for wearing test. The garment pressure was measured in front, side, and back parts of the body. The measured cardiopulmonary parameters were vital capacity, respiratory rate, heart rate, and blood pressure. The results were as follows: 1. The smaller the size of the Korean skirt-band, the greater the garment pressure. The pressure during inspiration was significantly greater than the pressure during expiration. 2. The pressure in side part was the greatest of the three measurements and the pressure in back part was the smallest. 3. The small size of the Korean skirt-band revealed low vital capcity and great respiratory rate. 4. As the small size grement was dressed, the respiratory rate and the heart rate during walking and rest after walking were significantly high. 5. Subjects felt uncomfortable when they wore small sized garment.

• 한국대기환경학회지
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• 제19권3호
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• pp.297-306
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• 2003

Works were focused on back pressure characteristics of ceramic fiber filter on DPF (Diesel Particulate Filter) system and experiments were performed to select appropriate filter which can filter particulates. Filters were installed on metal -support tube which has openings for exhaust gas flow. Ceramic fiber filters with high specific surface area and adequate high temperature strength are commercially available for filtration of diesel particulates and in -situ hot regeneration. Thus, ceramic blanket and ceramic board which are used as insulating media were applied to filter and filtration apparatus was installed on exhaust gas line connected to 2.0 L diesel engine. Alternating filter structure to adapt DPF system, collection efficiency test of diesel particulates was measured. In case of ceramic blanket, pressure drop was low, caused by the destruction of soft structures. Also, particulate collection efficiency was decreased depending on loading time. In case of ceramic board, structure design was altered to reduce back pressure on DPF system. Structure design was altered to induce Z-flow by making 10 mm and 5 mm holes on the surface of media. Alteration of 5 mm hole showed that media have low back pressure but particulate collection efficiency was 77%, while 10 mm hole showed that of 90%.

• 기술발표회
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• 통권2006호
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• pp.66-72
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• 2006

The ground anchoring has been utilized over 40 years. It is growing the application of the removal ground anchor with tension force for holding earth retaining constructions in the city. It transmits tension stress of prestressed steel wire through grouting to fixed the ground that is of great advantage adjacent ground stability. Nowadays, we can find the compression dispersion anchor on many site. But, it has some problems in behavior of anchors because of impossible to tense p.c strand uniformly under the existing equipment due to different length of p c strand. Hence, motive of this research was to study the application of the newly developed tension system, that analyze and compare with the current anchoring method build on the data of in-site test and laboratory test. As a result, in case of auto back tension system, it became clear that tension pressure was equally distributed among the steal wires but the existing tension system showed sign of instability by indicating stress deflection of about 30% compare with design load. This can cause an ultimate failure of the concentrated p.c strand and a shear failure of ground.

• 한국추진공학회지
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• 제25권6호
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• pp.12-19
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• 2021

액체 추진제 공급 시, 하류의 압력변동과 무관하게 일정한 유량을 공급하기 위한 캐비테이션 벤츄리의 실험적 연구가 수행되었다. 캐비테이션 벤츄리의 성능을 파악하기 위해 벤츄리를 설계, 제작하여 후단의 형상, 전단압, 그리고 배압에 따른 유량과 벤츄리 전·후단 압력비를 관찰하였다. 일반적으로 캐비테이션 벤츄리의 구조적인 형상에만 종속하는 벤츄리 임계압력비는 실험결과, 후단의 형상 및 벤츄리 전단압과 관계없이 0.74로 일정함을 확인하였다.

• 대한물리치료과학회지
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• 제31권2호
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• pp.1-14
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• 2024

Background: Many patients with chronic low back pain have reduced movement due to pain. For that reason, muscle strength weakens, which leads to pain again. The pain caused by such a vicious circle is not only caused by structural problems, but also by physical function, activity disorder, or psychological depression due to biopsychosocial approaches and pain neuroscience education was applied as an intervention to find out its effect. Therefore, this study was experimented with to find out the effects of pain neuroscience education on pain, physical function, activity disorder, and depression in patients with chronic low back pain. Design: Randomized control trial Method: The study subjects were 39 patients with chronic low back pain, and the study subjects were randomized through computers to the experimental group applying pain neuroscience education and the control group applying only general physical therapy and myofascial release techniques, and the experiment was conducted for 4 weeks. Pressure Pain Threshold , Schober test, Korean Roland-Morris Disability Questionnaire, Korean Oswestry Disability Index, and Korean Depression Screening Assessment were measured. Results: As a result of the study, there was no significant difference in pain neuroscience education compared to the group that applied only general physical therapy and myofascial release techniques in both lumbar pressure pain thresholds, Schober test, Korean Roland-Morris disability questionnaire, and Korean Oswestry disability questionnaire. However, the Korean Depression Screening Assessment which is the result of measuring depression, showed significant results(p<0.05). Conclusion: Therefore, it is believed that it can be a way to mediate the psychological part through pain neuroscience education for patients with chronic low back pain in the future.