• Journal of the Korean Wood Science and Technology
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• v.18 no.3
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• pp.42-52
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• 1990

In this study, thick 24mm glulams were composed of thick. 3, 4, 6, 8mm Larch laminas to study that the theoretical analysis and the experimental analysis regarding the location of neutral axis of the glulams were compared, and to study on the effect of location of neutral axis on mechanical properties of glulam. The variation of location of neutral axis after proportional limit(or elastical limit) was studied to offer basic data to make the better composition method of glulam. The result obtained can be summarized as follows: 1. The theoretical neutral axis was 0.547 in solid wood, and also 0.547 in glulams because glulams were composed of only Larch laminas. 2. In solid wood, the deviation of the theoretical and the experimental neutral axis location was 0.1%, But in glulams, the deviation from-12.2% to + 7.8% showed nonuniform pattern but no large deviation. Because laminas was only of Larch and so the mechanical properties of laminas were monotonous. 3. The neutral axis exerted no influance on the elasticity of glulam, which meaned that the maximum shear strength in the neutral axis showed no influance on elasticity limit. 4. The only minutely lower elasticities of glulam than that of solid wood were shown. This was because of influance of glue lines of glulam on the elasticlties. 5. The failure type of glulam was wholly simple tension failure and the horizontal shear failure near neutral axis was not taken place, which was that glue line was complete in bonding and the strength of the lamina was not various but uniform. 6. The ratio of tension strain($^{\varepsilon}t$) I compression strain($^{\varepsilon}c$) initially showed uniform level After the elasticity limit. the ratio was increased with the flow of time and so the tension strain was more increased than compression strain. So this proved tension lamination technique, which is that the mechanical properties of glulam could be improved, if the lamina of more superior strength would he added on the bottom side of the glulam.

• Journal of Korean Neurosurgical Society
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• v.49 no.6
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• pp.351-354
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• 2011

Objective : This investigation was conducted to evaluate a new, safe entry point for the C2 pedicle screw, determined using the anatomical landmarks of the C2 lateral mass, the lamina, and the isthmus of the pars interarticularis. Methods : Fifteen patients underwent bilateral C1 lateral mass-C2 pedicle screw fixation, combined with posterior wiring. The C2 pedicle screw was inserted at the entry point determined using the following method : 4 mm lateral to and 4 mm inferior to the transitional point (from the superior end line of the lamina to the isthmus of the pars interarticularis). After a small hole was made with a high-speed drill, the taper was inserted with a 30 degree convergence in the cephalad direction. Other surgical procedures were performed according to Harm's description. Preoperatively, careful evaluation was performed with a cervical X-ray for C1-C2 alignment, magnetic resonance imaging for spinal cord and ligamentous structures, and a contrast-enhanced 3-dimensional computed tomogram (3-D CT) for bony anatomy and the course of the vertebral artery. A 3-D CT was checked postoperatively to evaluate screw placement Results : Bone fusion was achieved in all 15 patients (100%) without screw violation into the spinal canal, vertebral artery injury, or hardware failure. Occipital neuralgia developed in one patient, but this subsided after a C2 ganglion block. Conclusion : C2 transpedicular screw fixation can be easily and safely performed using the entry point of the present study. However, careful preoperative radiographic evaluation, regardless of methods, is mandatory.

• The Korean Journal of Pain
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• v.9 no.2
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• pp.326-335
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• 1996

Background: Though a number of studies have described the distribution of substance P(SP)-like immunoreactivity in the spinal cord, they have been focused on lamina I and II of the dorsal horn and there are little morphological studies on the topographic distribution and ultrastructure of the SP immunoreactive neurons especially in the ventral horn of the spinal cord. this study was conducted to identify distribution pattern of SP immunoreactive neurons and to difine the synaptic organization of their processes in ventral horn of the thoracic cord of the cat by preembbeding immunocytochemical method using SP antiserum. Methods: Five adults cats of either sex were used and deeply anesthetized by intramuscular injection of ketamine. After removal of the spinal cord, samples of thoracic cord were taken and placed in fresh fixative at $4^{\circ}C$ for 2 hours. Transverse sections $50{\mu}m$ thick were processed using the preembbeding immunocytochemical method and incubated consecutively in the specific primary antibody and the 10% normal goat serum, the rabbit anti-substance P antiserum, the biotin-labelled goat anti-rabbit IgG and finally the avidin-biotin-peroxidase complex. The processed tissue sections were throughly washed and stained in the black with 1% uranyl acetate. Section were examined on a electron microscope. Results: 1) SP immunoreactive neurons were observed in the gray matter around central canal. 2) In lamina I and II SP immunoreactivity was observed in both myelinated and unmyelinated nerve fibers, but in ventral horn only in the unmyelinated nerve fibers. 3) SP immunoreactive axon terminals with small round and large dense core vesicles made chemical synapses onto the dendrites of motor neurons in the ventral horn. Conclusion: SP immunoreactive neurons might play an important role in modulation of motor neurons in the ventral horn of the thoracic cord of the cat.

• Journal of Korean Neurosurgical Society
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• v.59 no.6
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• pp.604-609
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• 2016

Objective : The aim of this study was to compare the clinical and radiological outcomes associated with the use of hydroxyapatite (HA) spacer and allogeneic bone (AB) spacer in laminoplasty. Methods : From January 2006 to July 2014, 79 patients with cervical spondylotic myelopathy or ossification of the posterior longitudinal ligament underwent cervical laminoplasty. The radiologic parameters were obtained from plain radiography and three-dimensional computed tomography. All images were taken before and after surgery. Cervical lordosis, spinal canal dimension, fusion between lamina and spacer, and resorption of spacer were checked. Clinical outcomes were assessed using visual analog scale and Japanese Orthopedic Association. Results : Double-door laminoplasty was performed on 280 levels : 182 in the HA group and 98 in the AB group. The mean follow-up was 23.1 months (range : 4-69 months). Similar fusion rates were found in these groups (p=0.3). The resorption rate between lamina and spacer was lower in the HA group (p<0.001). During the immediate postoperative period, the canal dimension of both groups increased compared with the results in the preoperative period. However, the canal dimension of the AB group decreased over time compared with that of the HA group (p<0.001). Conclusion : Double-door laminoplasty improved the clinical outcomes of both groups. However, the spinal canal dimension in the AB group showed a greater degree of reduction than in the HA group at the final postoperative follow-up. Therefore, we suggest that surgeons consider the use of larger-sized AB spacers in double-door laminoplasties.

• Development and Reproduction
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• v.8 no.1
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• pp.43-47
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• 2004

The present paper studied neurosecretory cell types and their seasonal secretory activity in the eyestalk of Palaemon macrodactylus. The samples were monthly collected in Nakdong estuary for one year. The eyestalk consisted of lamina ganglionaris, medulla externa medulla interna, and medulla terminaris. four types of neurosecretory, A-, B-, C- and D-cells are found in the eyestalk. The A-cells are located in the medulla externs. Althoush the B- and C-cells are located in the medulla interna and medulla terminalis, B-cells are predominant in medulla interna and C-cells are usually distributed in medulla terminaris. The size of D-cells are larger than other types of cells in size. The neurosecretory cells except D-cells show a remarkable change with month. The A-, B-, and C-cells are activated from March and April to July, and decreased at August.

• Journal of Korean Neurosurgical Society
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• v.58 no.5
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• pp.494-498
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• 2015

Objective : To describe a novel spinous process-splitting hemilaminoplasty technique for the surgical treatment of intradural and posterior epidural lesions that promotes physiological restoration. Methods : The spinous process was split, the area of the facet lamina junction was drilled, and en bloc hemilaminectomy was then performed. After removing intradural and posterior epidural lesions, we fitted the previously en bloc-removed bone to the pre-surgery same shape, and held it in place with non-absorbable sutures. Surgery was performed on 16 laminas from a total of nine patients between 2011 and 2014. Bony union of the reconstructed lamina was assessed using computed tomography (CT) at 6 months after surgery. Results : Spinous process-slitting hemilaminoplasty was performed for intradural extramedullary tumors in eight patients and for ossification of the ligament flavum in one patient. Because we were able to visualize the margin of the ipsilateral and contralateral dura, we were able to secure space for removal of the lesion and closure of the dura. None of the cases showed spinal deformity or other complications. Bone fusion and maintenance of the spinal canal were found to be perfect on CT scans. Conclusion : The spinous process-splitting hemilaminoplasty technique presented here was successful in creating sufficient space to remove intradural and posterior epidural lesions and to close the dura. Furthermore, we were able to maintain the physiological barrier and integrity after surgery because the posterior musculature and bone structures were restored.

• Clinical and Experimental Reproductive Medicine
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• v.30 no.2
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• pp.127-133
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• 2003

Objective: The aim of this study was to investigate the morphological aspects of testicular tissue before and after freezing-thawing by light and transmission electron microscopy. Methods: Tissue biopsies were carried out on mouse testis for freezing. Samples in medium containing 20% glycerol were frozen by computer-controlled freezing program. The effect of freezing-thawing on the structural change of testicular tissues were examined by light and electron microscopy. Results: The freezing-thawing procedure had no significant effect on tubular diameter. However, it caused folding of the lamina propria, and notable damage to Sertoli cells, spermatogonia and spermatocytes. The cells were detached, desquamated from the basal lamina and had increased vacuolization. Round spermatids, elongated spermatids and spermatozoa were less affected, and most of them maintained their normal structure. Conclusions: The structure of spermatogonia, spermatocyte and basal compartments in seminiferous epithelium was significantly altered by freezing-thawing procedure of mouse testicular tissues. Thus, we need to develop a more reliable method for the cryopreservation of testicular tissues.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.142-145
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• 2001

Supernumerary tooth is one of the abnormalities in tooth number. Supernumerary tooth result from excessive proliferation of dental lamina and incidence reports identify a range of $0.3\sim0.8%$ in primary dentition, $1.0\sim3.5%$ in permanent dentition with males being affected twice as frequently as females, maxilla nine times as frequently as mandible The incidence is more in anterior tooth region than in posterior region. The most common supernumerary tooth is the mesiodens, which located between maxillary central incisors. The occurrence is very rare in the incisor region of mandible and the reports on incidence is 2%. In this case, there were two supernumerary teeth in the mandibular region and we could acquire normal alignment of mandibular incisors by extraction and orthodontic treatment.

• Journal of Korean Neurosurgical Society
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• v.44 no.3
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• pp.116-123
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• 2008

Objective : The objective of this study is to investigate clinical characteristics, management methods and possible causes of intracranial fusiform aneurysm. Methods : Out of a series of 2,458 intracranial aneurysms treated surgically or endovascularly, 22 patients were identified who had discrete fusiform aneurysms. Clinical presentations, locations, treatment methods and possible causes of these aneurysms were analyzed. Results : Ten patients of fusiform aneurysm were presented with hemorrhage, 5 patients with dizziness with/without headache, 4 with ischemic neurologic deficit, and 1 with 6th nerve palsy from mass effect of aneurysm. Two aneurysms were discovered incidentally. Seventeen aneurysms were located in the anterior circulation, other five in the posterior circulation. The most frequent site of fusiform aneurysm was a middle cerebral artery. The aneurysms were treated with clip, and/or wrapping in 7, resection with/without extracranial-intracranial (EC-IC) bypass in 6, proximal occlusion with coils with/without EC-IC bypass in 5, EC-IC bypass only in 1 and conservative treatment in 3 patient. We obtained good outcome in 20 out of 22 patients. The possible causes of fusiform aneurysms were regard as dissection in 16, atherosclerosis in 4 and collagen disease or uncertain in 2 cases. Conclusion : There is a subset of cerebral aneurysms with discrete fusiform morphology. Although the dissection or injury of internal elastic lamina of the cerebral vessel is proposed as the underlying cause for most of fusiform aneurysm, more study about pathogenesis of these lesions is required.

• Atmosphere
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• v.20 no.3
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• pp.261-271
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• 2010

Carbon isotopic compositions of the YC-2 stalagmite in Yongcheon Cave were analyzed to delineate paleoclimatic variations near Korean peninsula for the past historical period. The YC-2 stalagmite is about 68 mm long and annual growth laminae are distinctively identified. Because the number of growth laminae is at least 242, the stalagmite can be estimated to be at least 241 years old. At about 15 mm from the bottom, one thick brown growth lamina is observed, and this lamina was likely to have been formed when the stalagmite ceased to grow, making the hiatus. High resolution, carbon isotope data indicate past fluctuations of East Asia monsoonal intensity (intimately related to the amount of precipitation). Based on the carbon isotope trend, the stalagmite can be divided into three stages (Stages I, II and III). The highest carbon isotopic compositions of Stage I (${\delta}^{13}C$=-3.3~0.4‰, PDB) indicate that the stalagmite grew during the Little Ice Age when cold and dry climate prevailed with less vegetation. Stage II is characterized by a transitional period from cold and dry to warm and wet climate with a increasing trend of carbon isotopic compositions (${\delta}^{13}C$=-9.6~-0.6‰) and this period indicates the weakening of the Little Ice Age climate. This decreasing trend also suggests that Little Ice Age was terminated near middle 1870's around Korean peninsula. Relatively low carbon isotopic compositions during Stage III (${\delta}^{13}C$=-11.0~-8.0‰) indicates that the climate was changed to warm and wet conditions which are similar to the present.