• Title/Summary/Keyword: eccentric

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Experimental Study on the Surface Pressure Characteristics of a Rear-Guider for the Various Design Factors of a Cross-Flow Fan (관류홴의 설계인자 변화에 따른 리어가이더의 표면압력 특성에 관한 실험적 연구)

  • Kim, J.K.
    • Journal of Power System Engineering
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    • v.9 no.3
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    • pp.50-57
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    • 2005
  • A cross-flow fan is strongly influenced by the various design factors of a rear-guider and a stabilizer. The purpose of this paper is to investigate the effects of a rear-guider and a stabilizer on the surface pressure of a rear-guider in an indoor room air-conditioner using a cross-flow fan. The design factors considered in this paper are a rear-guider clearance, a stabilizer clearance, and a stabilizer setup angle, respectively. The operating condition of a cross-flow fan was controlled by changing the static pressure and flowrate using a fan tester. All surface pressures of a rear-guider are differently distributed according to the stabilizer setup angle, and show a zero value in the flow coefficient, ${\Phi}{\fallingdotseq}0.5$ only of a stabilizer setup angle, $45^{\circ}$. Especially, they show a big negative value in the expansion angle larger than $34^{\circ}$ regardless of a rear-guider clearance, a stabilizer clearance, and a stabilizer setup angle. On the other hand, surface pressures for various stabilizer cutoff clearances are better than those for various rear-guider clearances.

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Minimally Invasive Coronary Artery Bypass without Extracorporeal Circulation - One case report - (심폐바이패스없이 제한적 전흉부개흉술로 시행한 관상동맥우회술 1례)

  • 서필원;김삼현;이상민;김영권;박이태
    • Journal of Chest Surgery
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    • v.29 no.11
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    • pp.1263-1266
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    • 1996
  • We have experienced a case of coronary artery bypass surgery without extracorporeal circulation through limited anterior thoracotomy. The lesion was a single vessel disease involving the take off of the left anterior descending artery(LAD) which showed tubular lesion with irregular contour and eccentric stenosis of more than 95% luminal narrowing. Percutaneous transluminal coronary angioplasty(PTCA) seemed to have moderate success rate and moderate complication rate. A segment of left internal mammary artery(LIMA) from the second rib down to the sixth rib was harvested through the bed of resected fourth costal cartilage. Anastomosis between LIMA and LAD was performed under beating condition. The patient was extubated in the operation room and showed excellent postoperative course without complications. The coronary angiography on the postoperative 7th day revealed good patency at the anastomosis site.

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Study on the Experiment of the Floating Ring Seal with Bump Foil for High Pressure Turbopump (범프 포일을 장착한 고압 터보펌프용 플로팅 링 실의 실험에 관한 연구)

  • Kim Kyoung-Wook;Kim Chang-Ho;Ahn Kyoung-Min;Lee Sung-Chul;Lee Yong-Bok
    • Tribology and Lubricants
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    • v.22 no.2
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    • pp.105-111
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    • 2006
  • The floating ring seal which is used in the high pressure turbo pump is frequently used in the oxidizer pump and the fuel pump of the turbo pump of the liquid propulsion rocket, because it is able to minimize clearance to decrease the leakage flow rate. Compared with contact seal, the floating ring seal has advantage of minimizing clearance without rubbing phenomenon. But, the floating ring seal has a tendency to increase instability in operating condition in the high speed region. In this research, we devised floating ring seal which is inserted bump in the outer surface in order to improve the stability in the high speed region. Through this work, we expect to improve stability of floating ring seal with increasing the direct damping coefficient of seal and decreasing the eccentricity ratio.

Scientific Revolution in the Lab: Mad Scientists' Labs in Victorian Novels (실험실의 과학 혁명-빅토리아시대 소설에 나타난 '미친' 과학자들의 실험실)

  • Choo, Jae-uk
    • Journal of English Language & Literature
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    • v.58 no.2
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    • pp.305-325
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    • 2012
  • It is by the mad scientists that the ontological and epistemological turn was made in that scientific era. They achieved a scientific revolution although they were regarded as eccentric, comic, unsound, and evil ones in the dark and dismal labs. Likewise, a scientist who would like to create an anomaly, something novel and abnormal, tended to be considered mad and treated as such either because of his scientific theory which differed from those of other scientists or because his obstinate methodology was often blamed for its immorality and profaneness. Despite the fanciful purpose and the anomalous way in which the mad scientists did their experiments, these were attempts to explore new scientific terrain and find something new or unexpected, which often raised controversies between the old paradigm and the new one. As Thomas Kuhn manifests, subsequently, "an older paradigm is replaced in whole or in part by an incompatible new one" and then, "there must be a conflict between the paradigm that discloses anomaly and the one that later renders the anomaly lawlike." In that sense, Frankenstein's, Jekyll's, and Moreau's eerie challenges can be interpreted as efforts to achieve the ambitious goal of solving the scientific mysteries of the world in such unfavorable environmental conditions as specified in the three novels.

Seismic evaluation and upgrading of RC buildings with weak open ground stories

  • Antonopoulos, T.A.;Anagnostopoulos, S.A.
    • Earthquakes and Structures
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    • v.3 no.3_4
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    • pp.611-628
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    • 2012
  • The inelastic earthquake response of existing, reinforced concrete buildings with an open ground story, designed according to the old Greek codes, is investigated before and after their seismic strengthening with steel braces restricted to the open ground stories. The seismic performance evaluation is based on Part 3 of Eurocode 8 for assessment and retrofitting of buildings. Three and five-story, symmetric and non-symmetric buildings are subjected to a set of seven pairs of synthetic accelerograms, compatible with the design spectrum, and conclusions are drawn regarding the effectiveness of the strengthening solutions. Seismic behavior of the selected models confirms results of previous work regarding the insufficient capacity of the open ground stories for design level earthquakes. It is also shown that strengthening only the weak ground story, a choice having the substantial advantage of low cost and continued usage of the building during its seismic retrofitting, can remove the inherent weakness without shifting the problem to the stories above and thus making such buildings at least as strong as those without a weak first story. This partial strengthening is possible for symmetric as well as eccentric buildings, in which torsion plays a further detrimental role.

Performance of fire damaged steel reinforced high strength concrete (SRHSC) columns

  • Choi, Eun Gyu;Kim, Hee Sun;Shin, Yeong Soo
    • Steel and Composite Structures
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    • v.13 no.6
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    • pp.521-537
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    • 2012
  • In this study, an experimental study is performed to understand the effect of spalling on the structural behavior of fire damaged steel reinforced high strength concrete (SRHSC) columns, and the test results of temperature distributions and the displacements at elevated temperature are analyzed. Toward this goal, three long columns are tested to investigate the effect of various test parameters on structural behavior during the fire, and twelve short columns are tested to investigate residual strength and stiffness after the fire. The test parameters are mixture ratios of polypropylene fiber (0 and 0.1 vol.%), magnitudes of applied loads (concentric loads and eccentric loads), and the time period of exposure to fire (0, 30, 60 and 90 minutes). The experimental results show that there is significant effect of loading on the structural behaviors of columns under fire. The loaded concrete columns result more explosive spalling than the unloaded columns under fire. In particular, eccentrically loaded columns are severely spalled. The temperature distributions of the concrete are not affected by the loading state if there is no spalling. However, the loading state affects the temperature distributions when there is spalling occurred. In addition, it is found that polypropylene fiber prevents spalling of both loaded and unloaded columns under fire. From these experimental findings, an equation of predicting residual load capacity of the fire damaged column is proposed.

Inelastic stability analysis of high strength rectangular concrete-filled steel tubular slender beam-columns

  • Patel, Vipulkumar Ishavarbhai;Liang, Qing Quan;Hadi, Muhammad N.S.
    • Interaction and multiscale mechanics
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    • v.5 no.2
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    • pp.91-104
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    • 2012
  • There is relatively little numerical study on the behavior of eccentrically loaded high strength rectangular concrete-filled steel tubular (CFST) slender beam-columns with large depth-to-thickness ratios, which may undergo local and global buckling. This paper presents a multiscale numerical model for simulating the interaction local and global buckling behavior of high strength thin-walled rectangular CFST slender beam-columns under eccentric loading. The effects of progressive local buckling are taken into account in the mesoscale model based on fiber element formulations. Computational algorithms based on the M$\ddot{u}$ller's method are developed to obtain complete load-deflection responses of CFST slender beam-columns at the macroscale level. Performance indices are proposed to quantify the performance of CFST slender beam-columns. The accuracy of the multiscale numerical model is examined by comparisons of computer solutions with existing experimental results. The numerical model is utilized to investigate the effects of concrete compressive strength, depth-to-thickness ratio, loading eccentricity ratio and column slenderness ratio on the performance indices. The multiscale numerical model is shown to be accurate and efficient for predicting the interaction buckling behavior of high strength thin-walled CFST slender beam-columns.

Experimental study on concrete-encased composite columns with separate steel sections

  • Xiao, Congzhen;Deng, Fei;Chen, Tao;Zhao, Zuozhou
    • Steel and Composite Structures
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    • v.23 no.4
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    • pp.483-491
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    • 2017
  • This paper presents an experimental study on the behavior of concrete-encased composite columns with multiseparate steel sections subjected to axial and eccentric loads. Six 1/4-scaled concrete-encased composite columns were tested under static loads. The specimens were identical in geometric dimensions and configurations, and the parameter of this experiment was the eccentricity ratio of the applied load. Each two of the specimens were loaded with 0, 10%, and 15% eccentricity ratios. The capacity, deformation pattern, and failure mode of the specimens were carefully examined. Test results indicate that full composite action between the concrete and the steel sections can be realized even though the steel sections do not connect with one another. The concrete-encased composite columns can develop stable behavior and sufficient deformation capacity by providing enough transverse reinforcing bars. Capacities of the specimens were evaluated based on both the Plain Section Assumption (PSA) method and the superimposition method. Results show that U.S. and Chinese codes can be accurate and safe in terms of bending capacities. Test results also indicate that the ACI 318 and Mirza methods give the best predictions on the flexural stiffness of this kind of composite columns.

A Facial Chuna Manual Therapy for Peripheral Facial Nerve Palsy

  • Park, Yu-Kyeong;Lee, Cho In;Lee, Jung Hee;Lee, Hyun-Jong;Lee, Yun-kyu;Seo, Jung-Chul;Kim, Jae Soo
    • Journal of Acupuncture Research
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    • v.36 no.4
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    • pp.197-203
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    • 2019
  • The purpose of this study was to investigate useful manual therapy techniques for peripheral facial nerve palsy and to propose guidelines to be applied for current manual therapy techniques. Several databases were searched to find manual therapies for facial palsy. These therapies included cervical, and temporomandibular joint chuna manual therapy, proprioceptive neuromuscular facilitation, neuromuscular re-education, facial exercise, and mime therapy. Both cervical, and temporomandibular joint chuna manual therapy release nerve compression, helping blood circulation and nerve conduction. Proprioceptive neuromuscular facilitation uses irradiation, bilateral activation, and eccentric facilitation to improve muscle power and symmetry. Neuromuscular re-education, as a retraining tool for facial movement patterns, enhances neuromuscular feedback. Facial exercise helps the patient continuously move and massage facial muscle themselves. Mime therapy aims to develop a conscious connection between the use of certain muscles and facial expressions. The use of facial chuna manual therapy for peripheral facial nerve palsy can stimulate the proprioceptive neuromuscular receptors in the face. Peripheral facial nerve palsy has 4 phases; progress phase, plateau phase, recovery phase, and sequelae phase. Each phase needs different treatments which include relaxation, assistance, resistance, origin-insertion extension, and nerve pathway expansion.

Surgical Strategies for Achilles Tendinopathy (아킬레스 건병증의 수술 전략)

  • Park, Hyun-Woo
    • Journal of Korean Foot and Ankle Society
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    • v.25 no.2
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    • pp.95-99
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    • 2021
  • The surgical treatment of Achilles tendinopathy can be considered after the failure of conservative treatment, and the surgical methods may be divided into two groups; treatments for insertional and non-insertional tendinopathy. In the case of insertional tendinopathy, debridement including tendon and calcification of the diseased lesion, reattachment of the tendon, and calcaneal ostectomy of the Haglund lesion are the primary treatments. If reattachment is not possible, reconstruction should be performed by other methods such as tendon transfer. As a result of surgery for insertional tendinopathy, there is an improvement in the pain and function after surgery, but there are some patients whose pain does not completely disappear. Some residual pain may persist; therefore, the overall success rate of the surgery can be expected to be 80% to 90%. For the patients of non-insertional tendinopathy, conservative treatment through eccentric exercise is the primary treatment, and most of them have reported good results. In case of failure after various conservative treatments, debridement of the diseased lesion and repair of the remaining tendon would be the primary surgical treatments. If the remaining tendon is not sufficient, reconstruction such as tendon transfer should be considered.