• Korean Journal of Applied Biomechanics
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• v.12 no.1
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• pp.173-191
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• 2002

The purpose of this study was defined efficient throw motion pattern to obtain the quantitative data and to achieve successful bowling through kinetic - kinematic variables on the throw motion. Subject of group composed of three groups : Higher bowlers who are two representative bowlers with 200 average points and one pro-bowler. Middle bowlers who are three common persons with 170 average points. Lower bowler who are three common persons with 150 average points. Motion analysis on throw motion in three groups respectively has been made through three-dimension cinematography using DLT method. Two high-speed video camera at operating 180 frame per secondary. One-way ANOVA has been used to define variable relations. Analyzed result and conclusion are the following : The displacement of back of the hand must have wider difference of each right-left displacement to increase the spin of the ball. In high bowlers group, difference between the front-rear position of back of the hand in case of success and that in case of failure in follow throw is 0.17m. That is to say, momentum in case of success come to increase greatly, compared with that in case of failure. To increase the spin of the ball, the potential difference should be narrower in follow through. In case of the high bowlers, the velocity of the front-rear direction of the back of the hand has been the fastest both in release and follow through, compared with those in other groups, which has contributed to increasing the spin force of the ball. The orders in the resultant velocity of the back of the hand has shown the this : the finger tip$\rightarrow$the back of the hand$\rightarrow$wrist.These orders made the proximal segment support the distal segment. The distal segment has provided the condition to accelerate the velocity. In case of failure, the suddenly increased velocity has caused the failure in the follow through. Acutely flexing the angle of the back of the hand has contributed to lifting to increase the spin of the ball.

• Membrane Journal
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• v.18 no.2
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• pp.132-137
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• 2008

Nanofiltration membranes were prepared based on coating a sulfonated comb-like copolymer layer on top of a poly(vinylidene fluoride) (PVDF) support. The comb-like copolymer comprising poly(vinyl chloride) backbone and poly(styrene sulfonic acid) side chains, i.e. PVC-g-PSSA was synthesized by atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of PVC. The successful synthesis of graft copolymers were confirmed by nuclear magnetic resonance ($^1H$-NMR), FT-IR spectroscopy and wide angle X-ray scattering (WAXS). Composite nanofiltration membranes consisting PVC-g-PSSA as a top layer exhibited the increase of both rejections and solution flux with increasing PSSA concentration. This performance enhancement is presumably due to the increase of SO3H groups and membrane hydrophilicity. The rejections of composite membranes containing 71 wt% of PSSA were 88% for $Na_2SO_4$ and 33% for NaCl, and the solution flux were 26 and $34L/m^2h$, respectively, at 0.3 MPa pressure.

• Journal of Korean Neurosurgical Society
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• v.56 no.2
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• pp.114-120
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• 2014

Objective : At present, gold-standard technique of cervical cord decompression is surgical decompression and fusion. But, many complications related cervical fusion have been reported. We adopted an extended anterior cervical foraminotomy (EACF) technique to decompress the anterolateral portion of cervical cord and report clinical results and effectiveness of this procedure. Methods : Fifty-three patients were operated consecutively using EACF from 2008 to 2013. All of them were operated by a single surgeon via the unilateral approach. Twenty-two patients who exhibited radicular and/or myelopathic symptoms were enrolled in this study. All of them showed cervical cord compression in their preoperative magnetic resonance scan images. Results : In surgical outcomes, 14 patients (64%) were classified as excellent and six (27%), as good. The mean difference of cervical cord anterior-posterior diameter after surgery was 0.92 mm (p<0.01) and transverse area was $9.77mm^2$ (p<0.01). The dynamic radiological study showed that the average post-operative translation (retrolisthesis) was 0.36 mm and the disc height loss at the operated level was 0.81 mm. The change in the Cobb angle decreased to 3.46, and showed slight kyphosis. The average vertebral body resection rate was 11.47%. No procedure-related complications occurred. Only one patient who had two-level decompression needed anterior fusion at one level as a secondary surgery due to postoperative instability. Conclusions : Cervical cord decompression was successfully performed using EACF technique. This procedure will be an alternative surgical option for treating cord compressing lesions. Long-term follow-up and a further study in larger series will be needed.

• Tunnel and Underground Space
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• v.21 no.4
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• pp.307-319
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• 2011

Cyclic loading due to traffic, excavation and blasting causes microcrack growth in rocks over long period of time, and this type of loading often causes rock to fail at a lower stress than its monotonically determined strength. Thus, the crack growth and coalescence under cyclic loading are important for the long-term stability problems. In this research, experiments using gypsum as a model material for rock are carried out to investigate crack propagation and coalescence under monotonic and cyclic loading. Both monotonic and cyclic tests have a similar wing crack initiation position, wing crack initiation angle, cracking sequence and coalescence type. Three types of crack coalescence were observed; Type I, II and III. Type I coalescence occurs due to a shear crack and Type II coalescence occurs through one wing or tension crack. For Type III, coalescence occurs through two wing or tension cracks. Fatigue cracks appear in cyclic tests. Two types of fatigue crack initiation directions, coplanar and horizontal directions, are observed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.999-1004
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• 2010

Recently, many technologies have been developed in order to satisfy stringent emission regulations. However, in the case of diesel engines, the stringent emission regulations with respect to NOx and PM have not yet been satisfied. A dramatic reduction in the NOx and PM emissions could be achieved by using after-treatment systems such as lean NOx trap (LNT) and urea-SCR systems. However, the high temperature in the exhaust pipe affects the spray behavior of the secondary injector, which is used for supplying the Urea-SCR. Because of this high temperature, it is difficult to achieve uniform distribution of the reducing agent in the manifold. In this paper, the characteristics of a urea-SCR injector used for injecting in the exhaust pipe are presented. The purpose of this study was to investigate the spray characteristics of the injector, such as the spray angle, injection quantity, and SMD. In addition, laser diagnostics and high-speed-camera images were used to analyze the injector spray characteristics and to present a distribution of reduction in the transparent manifold.

• Journal of Korean Society of Steel Construction
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• v.29 no.2
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• pp.135-145
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• 2017

This study is a secondary study that is a cyclic seismic test of High depth hybrid composite beam and column connection after the primary bending strength test of a high depth Hybrid composite beam. Total of 3 seismic test specimens were prepared to cyclic test. The bracket and beam web spliced by high strength bolt and the bracket and beam upper flange was spliced by welding. Test results showed that the seismic strength was higher than the plastic moment($M_p$) in the positive negative moment section, the requirement of composite intermediate moment frame wes satisfied. Therefore, the requirement of intermediate moment frame can be secured by applying the details of connection of this study results.

• Journal of the Korean Society of Safety
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• v.19 no.4 s.68
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• pp.141-149
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• 2004

The automobile equipped with a gasoline engine uses the ignition coil, namely, a high voltage generator, to make the mixed fuel ignited and burned in the combustion chamber, which results in the power to drive the engine. The ignition coil functions to convert a low voltage of the primary into a hiか voltage of the secondary by switching method, which will be transmitted to the electrode. Here, if the ignition coil has a defect even a little, it cannot function well. In this study, it was chosen epoxy molding ignition coil in recently and epoxy resin which is insulation material as specimens, and it was measured the characteristics of the partial discharge occurring to the specimens when those were applied to a voltage, and thereby, it was researched and analyzed the distribution of phase angle, amount and count of discharge due to the changing voltage, And as the result is applying to the actual automobile ignition system, it can be expected the enhancement of the performance of the ignition coil and the reliability of the electrical equipment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.9
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• pp.1-8
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• 2003

Velocity data were acquired at a series of stations in the chordwise direction above a delta wing with leading edge extension, using a triple axis hot film anemometry. Surveys normal to planform yield velocity field data at incidence angle of 24$^{\circ}$and 32$^{\circ}$at a centerline chord Reynolds number of $1.76{\times}10^6$. Experimental results of velocity measurements of mean velocity of three components gave a confidence to quantitative investigate the vortical flow field over a LEX-delta wing with this probe. The present experiments indicated the existence of both wing and LEX vortex where the local mean axial velocity is maximum. It also shown the development of secondary vortex of opposite sign of rotating above the wing surface near the leading edge. The insertion of probe across the flow field was found to have little influence on the position of the vortex core.

• Journal of Korean Neurosurgical Society
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• v.41 no.4
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• pp.241-245
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• 2007

Objective : So called "minimally invasive procedures" have evolved from chemonucleolysis, automated percutaneous discectomy, arthroscopic microdiscectomy that are mainly working within the confines of intradiscal space to transforaminal endoscopic technique to remove herniated epidural disc materials directly. The purpose of this study is to assess the result of endoscopic spinal surgery and favorable indication in the thoracolumbar spine. Methods : The records of 71 patients, 73 endoscopic procedures, were retrospectively analysed. Yeung Endoscopic Spine Surgery system with 7 mm working sleeve and $25^{\circ}$ viewing angle was used. The mean follow up period was 6 months [range, 3-9]. Results : Operated levels were from T12-L1 disc down to L5-L6 of S1 disc. Of 71 cases, 2 patients underwent transforaminal endoscopic surgery twice due to recurrence after initial operation. MacNab's criteria was used to assess the outcome. Favorable outcome, excellent of good, was seen in 78% [57 procedures] of the patients. Among 11 fair outcomes, only 1 procedure was followed by secondary open procedure, laminectomy with discectomy. Two of 5 poor outcomes were operated again by same procedure which resulted in fair outcomes. One patient with aggravated cauda equina syndrome remained poor and a lumbar fusion procedure was performed in other patient with poor outcome. There were 2 postoperative discitis that were treated with conservative care in one and anterior lumbar interbody fusion in the other. Conclusion : Evolving technology of mechanical, visual instrument enables minimal invasive procedure possible and effective. The transforaminal endoscopic spinal surgery can reach as high as T12-L1 disc level. The rate of favorable outcome is mid-range among reported endoscopic lumbar surgery series. Authors believe that the outcome will be better as cases accumulate and will be able to reach the fate of standard open microsurgery.

• Journal of Korean Neurosurgical Society
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• v.43 no.1
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• pp.5-10
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• 2008

Objective : To evaluate the surgical outcomes of ventral interbody grafting and anterior or posterior spinal instrumentation for the treatment of advanced spondylodiscitis with patients who had failed medical management. Methods : A total of 28 patients were evaluated for associated medical illness, detected pathogen, level of involved spine, and perioperative complications. Radiological evaluation including the rate of bony union, segmental Cobb angle, graft- and instrumentation-related complications, and clinical outcomes by mean Frankel scale and VAS score were performed. Results : There are 14 pyogenic spondylodiscitis, 6 postoperative spondylodiscitis, and 8 tuberculous spondylodiscitis. There were 21 males and 7 females. Mean age was 51 years, with a range from 18 to 77. Mean follow-up period was 10.9 months. Associated medical illnesses were 6 diabetes, 3 pulmonary tuberculosis, and 4 chronic liver diseases. Staphylococcus was the most common pathogen isolated (25%), and Mycobacterium tuberculosis was found in 18% of the patients. Operative approaches, either anterior or posterior spinal instrumentation, were done simultaneously or delayed after anterior aggressive debridement, neural decompression, and structural interbody bone grafting. All patients with neurological deficits improved after operation, except only one who died from aggravation as military tuberculosis. Mean Frankel scale was changed from $3.78{\pm}0.78$ preoperatively to $4.78{\pm}0.35$ at final follow up and mean VAS score was improved from $7.43{\pm}0.54$ to $2.07{\pm}1.12$. Solid bone fusion was obtained in all patients except only one patient who died. There was no need for prolongation of duration of antibiotics and no evidence of secondary infection owing to spinal instrumentations. Conclusion : According to these results, debridement and anterior column reconstruction with ventral interbody grafting and instrumentation is effective and safe in patients who had failed medical management and neurological deficits in advanced spondylodiscitis.