• The Korean Journal of Pain
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• v.21 no.3
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• pp.202-205
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• 2008

Background: Lumbar radicular pain is a frequent and often debilitating event. Although many treatment methods have been described in several studies, the available evidences regarding efficacy is not sufficient enough to draw definitive conclusions on an optimal therapy regime. Pulsed radiofrequency (RF) treatment was found to exert a beneficial effect on intractable radicular pain in individuals. The purpose of this study was to assess the efficacy of pulsed RF of the dorsal root ganglion for chronic lumbar radicular pain. Methods: Twenty five patients with chronic lumbar radicular pain that was refractory to selective nerve root blockage met the inclusion criteria of our study and received pulsed RF treatment. The average numeric rating scale (NRS) for leg pain during usual activities and the Oswestry disability index (ODI) were measured at 1 and 3 months after the procedure. Results: Of the 25 patients accepted for pulsed RF treatment, one dropped out due to a vertebral compression fracture during this study. ODI and NRS showed a positive trend in favor of the pulsed RF treatment. No significant complications were observed during the study period. Conclusions: It appears that pulsed RF treatment of the lumbar spinal dorsal root ganglion may be an effective treatment method for patients suffering from lumbar radicular pain, and who were not responsive to selective nerve root blockage.

• Journal of Powder Materials
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• v.5 no.2
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• pp.98-110
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• 1998

$Ti_{52}Al_{48}$ and $(Ti_{52}Al_{48})_{100-x}B_x(x=0.5, 2, 5)$ alloys have been Produced by mechanical milling in an attritor mill using prealloyed powders. Microstructure of binary $Ti_{52}Al_{48}$ powders consists of grains of hexagonal phase whose structure is very close to $Ti_2Al$. $(Ti_{52}Al_{48})_{95}B_5$ powders contains TiB2 in addition to matrix grains of hexagonal phase. The grain sizes in the as-milled powders of both alloys are nanocrystalline. The mechanically alloyed powders were consolidated by vacuum hot pressing (VHP) at 100$0^{\circ}C$ for 2 hours, resulting in a material which is fully dense. Microstructure of consolidated binary alloy consists of $\gamma$-TiAl phase with dispersions of $Ti_2AlN$ and $A1_2O_3$ phases located along the grain boundaries. Binary alloy shows a significant coarsening in grain and dispersoid sizes. On the other hand, microstructure of B containing alloy consists of $\gamma$-TiAl grains with fine dispersions of $TiB_2$ within the grains and shows the minimal coarsening during annealing. The vacuum hot pressed billets were subjected to various heat treatments, and the mechanical properties were measured by compression testing at room temperature. Mechanically alloyed materials show much better combinations of strength and fracture strain compared with the ingot-cast TiAl, indicating the effectiveness of mechanical alloying in improving the mechanical properties.

• Journal of Korean Neurosurgical Society
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• v.55 no.6
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• pp.337-342
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• 2014

Objective : To determine deformity correction by postural correction and subsequent balloon inflation in acute vertebral compression fractures (OVCFs) and to examine the effect of bone mineral density on deformity correction. Methods : A totol of 50 acute OVCFs received balloon kyphoplasty. Lateral radiographs were taken and analyzed at five different time points : 1) preoperative, 2) after placing the patient in prone hyperextended position, 3) after balloon inflation, 4) after deposition of the cement, and 5) postoperative. All fractures were analyzed for height restoration of anterior (Ha), middle (Hm) and posterior (Hp) vertebra as well as Cobb angle and Kyphotic angle. The bone mineral density (BMD) of lumbar spine was measured by dual-energy X-ray absorptiometry. According to the T-score, the patients were divided into two groups which were osteoporosis group and osteopenia group. Results : Postoperative measurements of Ha, Hm and the Cobb angle demonstrated significant reduction of 4.62 mm, 3.66 mm and $5.34^{\circ}$ compared with the preoperative measurements, respectively (each p<0.05). Postural correction significantly increased Ha by 5.51 mm, Hm by 4.35 mm and improved the Cobb angle by $8.32^{\circ}$ (each p<0.05). Balloon inflation did not demonstrate a significant improvement of Ha, Hm or the Cobb angle compared with baseline prone hyperextended. Postural correction led to greater improvements of Ha, Hm and Cobb angle in osteoporosis group than osteopenia group (each p<0.05). Conclusion : In acute OVCFs, the height restoration was mainly attributed to postural correction rather than deformity correction by balloon inflation. BMD affected deformity correction in the process of postural correction.

• Journal of Korean Neurosurgical Society
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• v.42 no.1
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• pp.6-10
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• 2007

Objective : The purpose of this study was to determine the effect of bone cement augmentation of pedicular screwing in severe osteoporotic spondylolisthetic patients. Methods : Twenty patients with spondylolisthesis (8 : spondylolytic spondylolisthesis 12 : degenerative spondylolisthesis) who had undergone pedicular screwing and interbody fusion for osteoporotic lumbar spine (T-score on bone mineral density<-3.0) from 2002 to 2005 were reviewed. Mean age was 62.3 years with 3 male and 17 female patients. Average follow-up period was 14 months. Average T-score on bone mineral density (BMD) was -3.62. After decompression of neural elements, about 6cc of polymethylmethacrylate (PMMA) was injected into the each vertebral body through transpedicular route. All patients underwent one level interbody fusion and pedicular screw fixation. Clinical outcome was assessed using Oswestry Disability Index (ODI) on the last clinical follow-up. In addition, a modified MacNab's grading criteria was used to objectively assess patient's outcome postoperatively. Radiographic analysis of sagittal contour was assessed preoperatively, immediately postoperatively, and at final follow-up including fusion rate. Results : Eighteen of 20 patients were graded as excellent or good according to the modified MacNab's criteria. An significant improvement of ODI was achieved in both groups. Mean sagittal angle at the preoperative state, postoperative state and at the last follow-up state was $11.0^{\circ},\;20.1^{\circ}$ and $18.3^{\circ}$, respectively, with mean sagittal angle correction gain $7.3^{\circ}$. Firm fusion was achieved in all patients. There were one compression fracture above the fused segment after 6 months follow-up and one case of seroma. But there were no postoperative complications related to bone cement leakage and pedicular screwings such as screw pullout or screw cut-up. Conclusion : Bone cement augmentation of pedicular screwing can be an effective procedure for osteoporotic lumbar spine in spondylolisthetic patients.

• Journal of Adhesion and Interface
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• v.18 no.3
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• pp.118-126
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• 2017

In a natural fiber-reinforced composite material, many studies have been devoted to improving the interfacial adhesion between natural fiber and polymer matrix and the composite properties through various fiber surface modifications. In the present study, waste wool-reinforced polypropylene matrix composites were fabricated by compression molding and their mechanical and impact properties were characterized. As a result, the tensile and flexural properties and the impact strength of waste wool/polypropylene composites strongly depended on the treatment medium, alkali treatment with sodium hydroxide (NaOH) and silane treatment with 3-glycidylpropylsilane(GPS). The composite with waste wool by silane treatment exhibited higher mechanical properties and impact resistance than that by alkali treatment. The fracture surfaces of the composites support qualitatively the increased properties, showing the improved interfacial bonding between the waste wool and the polypropylene matrix.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.141-148
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• 2016

This paper employed finite element method (FEM) to study the dynamic response of Steel Fiber-Reinforced Concrete(SFRC) panels subjected to impact loading by spherical projectiles. The material properties and non-linear stress-strain curves of SFRC were obtained by compression test and flexural test. Various parametric studies, such as the effect of fiber volume fraction and thickness of panels, are made and numerical analyses are compared with experiments conducted. It is shown that protective performance of concrete panels will be improved by adding steel fiber. Area loss rates and weight loss rates are decreased with increasing fiber volume fraction. Also, penetration modes can be expected by FEM, showing well agreement with experiment. Results can be applied for designing the protection of military structures and other facilities against high-velocity projectiles.

• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.345-356
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• 2008

In the previous study, direct inelastic strut-and-tie model (DISTM) was developed to perform inelastic design of reinforced concrete members by using linear analysis for their secant stiffness. In the present study, for convenience in design practice, the DISTM was further simplified so that inelastic design of reinforced concrete members can be performed by a run of linear analysis, without using iterative calculations. In the simplified direct inelastic strut-and-tie model (S-DISTM), a reinforced concrete member is idealized with compression strut of concrete and tension tie of reinforcing bars. For the strut and tie elements, elastic stiffness or secant stiffness is used according to the design strategy intended by engineer. To define the failure criteria of the strut and tie elements, concrete crushing and reinforcing bar fracture were considered. The proposed method was applied to inelastic design of various reinforced concrete members including deep beam, coupling beam, and shear wall. The design results were compared with the properties and the deformation capacities of the test specimens.

• Journal of Physiology & Pathology in Korean Medicine
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• v.28 no.2
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• pp.129-136
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• 2014

The "WuQinXi" exercise, one of the medical Qi-gongs, is an exercise maximizing human's self healing power and has been confirmed to be effective significantly at several modern researches. There are many exercise therapies in western medcine, such as Willams's flexion exercise, Mckenzie's extension exercise, vertebral stabilization exercise and so on. However, there isn't a special exercise therapy which can be applied for medical practice in oriental medicine. So we selected 24 motions which are related with lumbar movements from 3 type "WuQinXi" exercises ; 20 mode, 30 mode, and 40 mode. And then, we classified them according to lumbar movements as flexion, extention, lateral bending and rotation, and also functions as stabilization and rubbing. Next, with these classifications, we assorted them by kinds of lumbar spinal disease as HIVD(herniation of intervertebral disc), spinal stenosis, spondylolysis and spondylolisthesis, facet joint syndrome, compression fracture and spondylosis. We expect that "WuQinXi" exercise be a exercise therapy for lumbar spinal disease at an oriental medical clinic in this way. Oriental medical doctors will be able to teach easily patients "WuQinXi" exercise's motions at clinic, depending on kinds of lumbar spinal disease each patient suffers from. We plan to study the effect of "WuQinXi" exercise by comparing patients who do the "WuQinXi" exercise with the patients who do the western medical exercise therapy.

• Computers and Concrete
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• v.22 no.1
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• pp.93-100
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• 2018

It is seldom possible that geotechnical materials like rocks and concretes found without joints, cracks, or discontinuities. Thereby, the impact of micro-cracks on the mechanical properties of them is to be considered. In the present study, the effect of micro-crack on the failure mechanism of rock specimens under uniaxial compression was investigated experimentally. For this purpose, thermal stress was used to induce micro-cracks in the specimens. Several cylindrical and disk shape specimens were drilled from granite collected from Zanjan granite mine, Iran. Some of the prepared specimens were kept in room temperature and the others were heated by a laboratory furnace to different temperature levels (200, 400, 600, 800 and 1000 degree Celsius). During the experimental tests, Acoustic Emission (AE) sensors were used to monitor specimen failure at the different loading sequences. Also, Scanning Electron Microscope (SEM) was used to distinguish the induced micro-crack by heating in the specimens. The fractographic analysis revealed that the thin sections heated to $800^{\circ}C$ and $1000^{\circ}C$ contain some induced micro-fractures, but in the thin sections heated to $200^{\circ}C$, $400^{\circ}C$ and $600^{\circ}C$ have not been observed any micro-fracture. In the next, a comprehensive experimental investigation was made to evaluate mechanical properties of heated and unheated specimens. Results of experimental tests showed that induced micro-cracks significantly influence on the failure mode of specimens. The specimens kept at room temperature failed in the splitting mode, while the failure mode of specimens heated to $800^{\circ}C$ are shearing and the specimens heated to $1000^{\circ}C$ failed in the spalling mode. On the basis of AE monitoring, it is found that with increasing of the micro-crack density, the ratio of the number of shear cracks to the number of tensile cracks increases, under loading sequences.

• Clinics in Shoulder and Elbow
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• v.5 no.1
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• pp.29-36
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• 2002

Purpose : Cubitus varus deformity has been reported to cause ulnar neuropathy. We present five cases of tardy ulnar nerve palsy due to cubitus vus and analyzed the factors related to the nerve plasy caused by the deformity. Materials and Methods : Three men and two women were reviewed retrospectively and the mean age of the patients were 26 (range, 14-38). The average interval from initial fracture to nerve palsy was 19 years (8-32 years). The severity of symptoms, according to McGowan's classification, was grade I of 2 patients, grade Ⅱ of 3 patients. Carrying angle was an average of 18。 (30° -45° ). Internal rotation angle measured by Yamamoto's method was an average of 33° (30° -45° ). Results ㆍ The mean follow-up period was 53 months (35-70 months). Elbow pain and numbness of the fingers were relieved shortly after surgery. It revealed that anterior subluxation of the nerve due to internal rotation deformity and compression of the nerve between the medially shifted medial head of triceps and the medial epicondyle. Conclusion : The major entrapment point of the nerve is the fibrous band between the two heads of the flexor carpi ulnaris. The severe internal rotation deformity may contribute the cause of tardy ulnar nerve palsy in cubitus varus deformity.