• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.58-65
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• 1999

The spinning machine has been developed for a bus and truck wheel disc which is manufactured by spinning process method. This machine has the mechanical structure with bed, 2-column, cross head, 2-vertical slide, 2-horizontal slide with forming roller, clamp slide and main spindle similar to large size vertical lathe. Main spindle attached the mandrel is rotated about 500rpm drived by 280kW power DC motor, and a rotating black material pressed on the mandrel with the clamp slide is spinformed by 2-forming rollers which are attached inner end of the 2-horizontal slides. The 2-vertical and 2-horizontal slides are actuated by the hydraulic cylinder which is controlled by the servo valve individially, and these servo valves are controlled by control signal of the CNC controller which is computed with position signal feedbacked from the encoder sensor. The developed machine can manufacture wheel disc of various section profile without mandrel change because section profile is easily modified using program editing in the CNC controller processor. The wheel disc manufactured by spinning process method has many advantages that the endurance is increased by 2 times and the weight is decreased by 30% compared with a conventional disc.

• Journal of Korean Neurosurgical Society
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• v.39 no.6
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• pp.432-437
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• 2006

Objective : In order to establish the index of degeneration, the authors performed a histochemical study with Safranin-O staining and investigated the occurrence of apoptosis in the human intervertebral disc. Methods : Eighteen intervertebral disc specimens surgically extracted from the patients and two additional specimens from the autopsied cases were stained with Safranin-O for proteoglycan according to a standard protocol. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate- biotin nick end labeling[TUNEL] was used to detect the fragmented DNA known to be associated with apoptotic cell death and classification scheme was formulated for categorization of the degree of Safranin-O staining [normal, moderate reduction, faint] by modification of Makin's histological-histochemical grading. The Kruskal-Wallis H test and Chi-square test were used for statistical analysis. Results : The statistical results showed a significant difference in the mean age between "normal" Safranin-O staining group and the others [19.3 versus 55, 43.4, p=0021]. However, there was no statistically significant correlation between Safranin-O staining and MR grading of disc degeneration. Only six of eighteen surgical specimens and none in autopsies showed positive apoptotic cells in TUNEL staining. Conclusion : The determination of the degree of degeneration in surgically obtained disc tissue per se by histochemical staining or by the degree of apoptosis that corresponds to its morphologic change was not feasible.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.3
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• pp.127-132
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• 2010

Eigensolutions associated with self-excited vibration of disc brake system can be obtained by complex eigenvalue analysis. The eigenvalue sensitivity to change in contact stiffness can be used to demonstrate stability criteria and eigenvalue veering. Dynamic instability on eigenvalue loci with respect to the variation of contact stiffness is found to be related to mode interaction between two adjacent modes. This modal interaction can be effectively shown by mode shape visualization. This paper presents the methodology to construct the mode shape of disc brake system where a disc and two brake pads are coupled with contact stiffness.

• Journal of the Korean Society of Marine Environment & Safety
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• v.7 no.3
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• pp.75-84
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• 2001

Ultrasonic vibrator is an equipment which atomizes and homogenizes the oils by breaking the oil particles with ultrasonic vibration cavity, and possibly improves the properties. There are various parameters on the effect of ultrasonic irradiation. Especially, this study intended to investigate the matrix structure of sludge oils and the erosion damages for horn disc SS41 according to the variation of the oil temperature and the immersing depth of horn disc. Sludge oils were irradiated with ultrasonic vibration and then observed the aspects of the change of oil particles. From these, the recycling feasibility of sludge oil for useable oil to be burnt was determined. The erosion damages for horn disc SS41 were examined with weight loss, weight loss rate and the irradiation time to max. erosion rate. These data will be useful to the development of ultrasonic breaking systems to recycle sludge oil and to consider a countermeasure for the prevention of erosion damages.

• The Journal of Korean Physical Therapy
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• v.18 no.6
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• pp.43-49
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• 2006

Purpose: Changes of degenerative disc have been analyzed or with the Magnetic Resonance Imaging (MRI) to assign appropriate meaning, and the relationship between the degenerative changes of the discs and its living function has been evaluated through the living function evaluation scores collected by functional rating index. Methods: in April, 2006, a physical examination was conducted for physical laborers to be employed as on-site laborer in a steel industrial complex located at a region. A month later, these 20 laborers who participated in lumbar vertebra MRI tests have been investigated for one-to-one mobile phone functional rating index test. Excluding 3 of 14 respondents whom scored 0 in functional rating index, the rest of respondents' degenerative disc grade changes shown in MRI and its relationship to living functional rating index have been performed. Results: The Dabbs method of measuring disc height resulted to show significant increase as the disc height changes from L1-2 level to L5-S1 level (p<0.01). However, there was no statistical significance with a relationship between disc height and functional rating index, and disc height average. The Magnetic Resonance Imaging analysis regard on the degree of disc degeneration and its relationship to living functional rating proved to have significant relationship (p<0.05). Conclusion: The degenerative changes monitored by Magnetic Resonance Imaging show significant relationship (p<0.05) to living function. However, this relationship could vary depend upon the characteristics of study population. So, it suggested that the future studies should be performed by considering population's age and job career.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.5
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• pp.543-549
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• 2008

Distraction osteogenesis is a commonly used technique for mandibular lengthening, but changes in the temporomandibular joint(TMJ) have not been well documented. The TMJ is one of the most complex joint in the body and is composed of a fibrous surface layer, a proliferative zone, hypertrophic cartilage, and bone. The shape and role of the TMJ change and modify during a person's life-time. Possible complications that can arise after mandibular distraction include failure of the formation, failure of callus, infection, disturbance of TMJ and of occlusion. However, there are only a few reports on changes in the TMJ as a result of distraction osteogenesis. Hence, the goal of this study was to evaluate the change of the TMJ after experimental distraction of mandibular ramus in rabbit. We studied histological changes of mandibular condyle, articular disk and retrodiscal tissue, and also examined the collagen I gene expression and MMP-1 gene expression. The results were as follows. 1. In the histological staining, experimental condylar surface showed more thick fibrous articular layer and proliferative layer, compared with the control condyle and experimental articular disc showed thick and dense collagen fibers compared with the control disc. 2. In the collagen I and MMP-1 gene RT-PCR analysis, experimental discs showed increased collagen I expression compared with the control disc, while MMP-1 gene expression was decreased compared with the control disc. The retrodiscal tissue was almost equal expressions of the collagen I and MMP-1 genes compared with the control retrodiscal tissue. These findings suggest that histological and biomolecular changes occur in condyles and discs after unilateral mandibular distraction osteogenesis.

• Journal of Forest and Environmental Science
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• v.32 no.3
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• pp.262-269
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• 2016

The purposes of this study are to calculate the green and dried weight using wood discs, to figure out weight change on air drying times, and to develop the model of wood disc weight change for Larix kaempferi, Pinus koraiensis, and Pinus densiflora. The variables affecting the weight change were investigated, and the pattern of weight change over time was figured out through linear models. When comparing the stem green weight calculated using wood discs in this study with the weight table of Korea Forest Service, the weight was not significantly different for L. kaempferi and P. koraiensis. On the other hand, in comparison of stem dried weight, the weight was significantly different in all of three species. In addition, various measurement factors were examined to figure out the relationship with weight change, and air drying times and disc diameter were found as significant independent variables. Finally, two linear models were developed to estimate air drying times of three species, fit statistics were significant for practical use.

• Journal of Korean Neurosurgical Society
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• v.46 no.6
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• pp.515-521
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• 2009

Objective : The purpose of this study was to compare clinical and radiological outcomes of percutaneous endoscopic lumbar discectomy (PELD) and open lumbar microdiscectomy (OLM) for recurrent disc herniation. Methods : Fifty-four patients, who underwent surgery, either PELD (25 patients) or repeated OLM (29 patients), due to recurrent disc herniation at L4-5 level, were divided into two groups according to the surgical methods. Excluded were patients with sequestrated disc, calcified disc, severe neurological deficit, or instability. Clinical outcomes were assessed using Visual Analogue Scale (VAS) score and Oswestry Disability Index (ODI). Radiological variables were assessed using plain radiography and/or magnetic resonance imaging. Results : Mean operating time and hospital stay were significantly shorter in PELD group (45.8 minutes and 0.9 day, respectively) than OLM group (73.8 minutes and 3.8 days, respectively) (p < 0.001). Complications occurred in 4% in PELD group and 10.3% in OLM group in the perioperative period. At a mean follow-up duration of 34.2 months, the mean improvements of back pain, leg pain, and functional improvement were 4.0, 5.5, and 40.9% for PELD group and 2.3, 5.1, and 45.0% for OLM group, respectively. Second recurrence occurred in 4% after PELD and 10.3% after OLM. Disc height did not change after PELD, but significantly decreased after OLM (p = 0.0001). Neither sagittal rotation angle nor volume of multifidus muscle changed significantly in both groups. Conclusion : Both PELD and repeated OLM showed favorable outcomes for recurrent disc herniation, but PELD had advantages in terms of shorter operating time, hospital stay, and disc height preservation.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.176-182
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• 2006

Although several artificial disc designs have been developed for the treatment of discogenic low back pain, biomechanical changes with its implantation were rarely studied. To evaluate the effect of artificial disc implantation on the biomechanics of functional spinal unit, a nonlinear three-dimensional finite element model of L4-L5 was developed with 1-mm CT scan data. Biomechanical analysis was performed for two different types of artificial disc having constrained and unconstrained instant center of rotation(ICR), ProDisc and SB Charite III model. The implanted model predictions were compared with that of intact model. Angular motion of vertebral body, forces on the spinal ligaments and facet joint, and stress distribution of vertebral endplate for flexion-extension, lateral bending, and axial rotation with a compressive preload of 400N were compared. The implanted model showed increased flexion-extension range of motion compared to that of intact model. Under 6Nm moment, the range of motion were 140%, 170% and 200% of intact in SB Charite III model and 133%, 137%, and 138% in ProDisc model. The increased stress distribution on vertebral endplate for implanted cases could be able to explain the heterotopic ossification around vertebral body in clinical observation. As a result of this study, it is obvious that implanted segment with artificial disc suffers from increased motion and stress that can result in accelerated degenerated change of surrounding structure. Unconstrained ICR model showed increased in motion but less stress in the implanted segment than constrained model.

• Journal of Korean Neurosurgical Society
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• v.51 no.1
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• pp.8-13
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• 2012

Objective : This is prospective study of clinical outcomes of percutaneous plasma disc coagulation Therapy (PDCT) in patients with herniated lumbar disc disease (HLD) to evaluate the safety and efficacy in its clinical application and usefulness as a reliable alternative to microscopic discectomy. Methods : Forty-six patients were enrolled in this study from April 2006 to June 2010. All patients had one-level HLD. Disc degeneration was graded on routine T2-weighted magnetic resonance Image (MRI) using the Pfirrmann's grading system and all index levels were grade 3 and grade 4. Indications for surgery were radiculopathy caused by disc protrusion with soft consistency. MRI was done at one month after the procedure in all patients to check post-PDCT change. The clinical outcomes were evaluated using Visual Analog Scales (VAS) score and MacNab's criteria. Results : This study was approved by the Institutional Review Board of our institution. The age of the study population ranged from 16 to 59 years with a mean age of 37.2 years. There were 29 males and 17 females in this study. The mean period of clinical follow-up was 21 months. The average preoperative VAS score for radiculopathy was $7.4{\pm}1.4$, while the final follow-up VAS score was $1.4{\pm}0.7$ (p<0.001). In MacNab's criteria, 41 patients (89.1%) had achieved favorable improvement (excellent and good) until later follow-up. There were one patient from infection and two patients who needed to convert to open discectomy. Conclusion : PDCT is a safe and efficient treatment modality in a selective patient with HLD.