• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05c
• /
• pp.10-14
• /
• 2001

In order to assess the long-tenn reliability of polymer insulators for distribution power systems, we have developed the accelerated aging test method which can simulate the operation conditions. In this study, 3000 hours aging test for 4 kinds of polymer insulators has been completed by the developed accelerated aging test. After 3000 hours aging test, visual inspection and electrical tests were carried for identifying a change of characteristics. Some specimens showed the surface erosion and the manufacturing defect. In the electrical tests, the wet flashover voltage was significant1y decreased by the accelerated aging test. In comparison with the field-aged polymer insulators, it can be concluded that the developed test method can evaluate the long-tenn reliability within short time and screen the manufacturing defect.

• Journal of Korean Neurosurgical Society
• /
• v.46 no.3
• /
• pp.232-238
• /
• 2009

Objective : Intracranial aneurysms are sometimes presented with visual symptoms by their rupture or direct compression of the optic nerve. It is because their prevalent sites are anatomically located close to the optic pathway. Anterior communicating artery is especially located in close proximity to optic nerve. Aneurysm arising in this area can produce visual symptoms according to their direction while the size is small. Clinical importance of visual symptoms presented by aneurysmal optic nerve compression is stressed in this study. Methods : Retrospective analysis of ruptured anterior communicating artery aneurysms compressing optic apparatus were carried out. Total 33 cases were enrolled in this study. Optic nerve compression of the aneurysms was confirmed by the surgical fields. Results : In 33 cases among 351 cases of ruptured anterior communicating artery aneurysms treated surgically, from 1991 to 2000, the dome of aneurysm was compressed in optic pathway. In some cases, aneurysm impacted into the optic nerve that deep hollowness was found when the aneurysm sac was removed during operation. Among 33 cases, 10 cases presented with preoperative visual symptoms, such as visual dimness (5), unilateral visual field defect (2) or unilateral visual loss (3), 20 cases had no visual symptoms. Visual symptoms could not be checked in 3 cases due to the poor mental state. In 6 cases among 20 cases having no visual symptoms, optic nerve was deeply compressed by the dome of aneurysm which was seen in the surgical field. Of 10 patients who had visual symptoms, 8 showed improvement in visual symptoms within 6 months after clipping of aneurysms. In 2 cases, the visual symptoms did not recover. Conclusion : Anterior communicating artery aneurysm can cause visual symptoms by compressing the optic nerve or direct rupture to the optic nerve with focal hematoma formation. We emphasize that cerebral vascular study is highly recommended to detect intracranial aneurysm before its rupture in the case of normal CT findings with visual symptoms and frequent headache.

• Journal of Korean Neurosurgical Society
• /
• v.59 no.3
• /
• pp.314-318
• /
• 2016

Posterior fossa is a site next to the middle fossa where arachnoid cyst frequently occurs. Generally, most arachnoid cysts are asymptomatic and are found incidentally in most cases. Although arachnoid cysts are benign and asymptomatic lesions, patients with posterior fossa arachnoid cysts often complain of headaches, gait disturbance, and ataxia due to the local mass effects on the cerebellum. We observed a patient with a posterior fossa arachnoid cyst who had visual symptoms and a headache, but did not have gait disturbance and ataxia. We recommended an emergency operation for decompression, but the patient refused for personal reasons. After 7 days, the patient revisited our hospital in a state of near-blindness. We suspected that the arachnoid cyst induced the hydrocephalus and thereby the enlarged third ventricle directly compressed optic nerves. Compressed optic nerves were rapidly aggravated during the critical seven days; consequently, the patient's vision was damaged despite the operation. Considering the results of our case, it is important to keep in mind that the aggravation of symptoms cannot be predicted; therefore, symptomatic arachnoid cysts should be treated without undue delay.

• Journal of Yeungnam Medical Science
• /
• v.24 no.2
• /
• pp.329-332
• /
• 2007

Solar retinopathy is a rare but well-recognized clinical entity of macular damage, caused by viewing a solar eclipse or direct sun gazing. A 21-year-old man gazed at the sun for approximately thirty seconds at noon using a monocular telescope with his left eye. Forty-eight hours after sun gazing, the patient experienced symptoms of blurred vision and central scotoma in the left eye. Eight months after sun gazing, the visual acuity decreased from 1.0 to 0.1 in the left eye and the fundus examination showed a round, yellowish-white discoid lesion at the left fovea. Fluorescein angiography showed an early window defect in the fovea of the left eye, that persisted without size change during the late phase resulting from atrophy of the retinal pigment epithelium. A small, central scotoma of the left eye was also found in the visual field test. The visual acuity was unchanged at the end of a one-year follow-up period.

• The Journal of Internal Korean Medicine
• /
• v.40 no.5
• /
• pp.797-803
• /
• 2019

Introduction: The aim of this study was to report the effect of Korean medicine treatments on a stroke patient with homonymous hemianopsia. Case Presentation: A 50-year-old male with a posterior cerebral artery infarction had continuously deteriorating symptoms of right homonymous hemianopsia, fatigue, dizziness, and light sensitivity. Treatment with Korean medicine therapy, including acupuncture and herbal medicine significantly improved the patient's symptoms. The result of a visual field test (VFI) was also improved after treatment, and no side effects were observed during treatment. Conclusion: Korean medicine treatment can be considered an effective treatment for homonymous hemianopsia in stroke patients.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.15 no.4
• /
• pp.60-66
• /
• 2016

This study used an ultrasound infrared thermography technique to detect issues in the motor core of typical power equipment. The current defect inspection method of the motor core is often incomplete (due to the limits of visual inspection) and thus the reliability of the motor core is reduced. Therefore, in this study, experiments were carried out to increase the reliability of the test by using an ultrasonic infrared thermal non-destructive inspection method to image the motor core. The ambient temperature of the experimental system was maintained at $25^{\circ}C$. Experiments were carried out to examine a damaged motor core and a defect-free motor core. Experimental results confirm the technique clearly detected defects in the motor core, thereby confirming the possibility of using this technique in the field.

• Brain Tumor Research and Treatment
• /
• v.6 no.2
• /
• pp.82-85
• /
• 2018

Extremely massive sellar xanthogranuloma (XG) are rare, and the surgical outcome and prognosis are not well known. XG remain unknown whether they are derived from Rathke's cleft cysts (RCCs) or craniopharyngiomas (CPs) following extensive inflammation and metaplasia, to the point that no epithelium is readily identifiable. These lesions usually tend to occur in younger patients (mean 28.3 years), have a smaller diameter, and remain primarily intrasellar region with infrequent calcification. This 36-year-old man presented our hospital with visual deterioration. At the time of visit, there were no neurological problems other than visual field defect and hormonal disorder. He visited our hospital in 2007 due to headache and decreased vision, and underwent transphenoid surgery for pituitary RCC. Since then, he has received treatment at our hospital for postoperative hormonal disorders. Through preoperative imaging study, the author suspected CP and underwent surgery. During the operation, the adhesion of the tumor to the surrounding major neurovascular structures was severe in the naked eyes, but the tumor could be removed more easily than expected. The postoperative histological findings were confirmed as XG. The postoperative course was uneventful. Compared to the previous literature, this case is a case where the size of XG is very large in a sellar region and it can be proved that it originated from the RCC. And regular follow-up is necessary to confirm the prognosis after surgery.

• Annals of Clinical Neurophysiology
• /
• v.4 no.2
• /
• pp.140-145
• /
• 2002

Neurologic sequelae of tuberculous meningitis include hemiparesis, paraparesis, quadriparesis, aphasia, developmental delay, dementia, blindness, visual field defect, deafness, cranial nerve palsies, epilepsy, and hypothalamic and pituitary dysfunction. But cervical epidural abscess and cervical spondylitis are rare. A 64-year-old woman who was diagnosed as tuberculous meningitis presented a severe neck pain and stiffness after 3 weeks of anti-tuberculous medication. Electromyography and cervical X-ray showed a cervical spondylosis with polyradiculopathy. But cervical MRI showed an acute cervical epidural abscess and mild cervical spondylitis. After continuous anti-tuberculous medication with supportive care, she showed a slow clinical improvement. But about 1 month of anti-tuberculous therapy, she presented a more aggravation of neck pain, neck stiffness, radicular pain, and neck motion limitation. Follow-up cervical MRI showed an more advanced cervical spondylitis. Afterthen she has recovered slowly by cervical laminectomy with posterior stabilization and continuous anti-tuberculous medication.

• Journal of Chest Surgery
• /
• v.21 no.6
• /
• pp.990-995
• /
• 1988

Seventeen cases of vascular injuries treated in Chungnam National University Hospital during the period from Apr. 1980 to Sep. 1988 were reviewed. Common causes of injuries were stab wound, automobile accidents and iatrogenic injuries. Of the 11 arterial injuries, 3 were femoral artery which was the commonest in frequency, the next was 2 cases of subclavian, common carotid, iliac artery. Of the 10 venous injuries, the subclavian vein and internal jugular vein were common in frequency. The most frequent type of injuries was laceration[13 cases in 21]. Vascular reconstruction was done by lateral suture repair in 8 cases, autogenous vein graft in 2, prosthetic vascular graft in 5, direct anastomosis in 1 case. Simple ligation was done in 5 cases. There was 1 case of visual field defect as a sequelae in right common carotid artery transaction and 1 case of mortality.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.5C no.5
• /
• pp.214-216
• /
• 2005

Photoreflectance (PR) has been measured to investigate the characterization of the $Al_{0.20}Ga_{0.80}As$/GaAs heterostructures. In the PR spectrum, the 'C' peak is confirmed as the carbon defect with residual impurity originating from the growth process. After annealing, binding energy is relatively weak with As evaporation being done to increase Ga. Also obtained is the electric field value according to annealing temperature ($300{\sim}800^{\circ}C$).