• Textile Coloration and Finishing
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• v.30 no.4
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• pp.313-320
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• 2018

As carbon fiber reinforced composites(CFRP) are widely used in aerospace, automobile, marine, and sports goods applications, they have been studied extensively by various researchers. However, CFRP have been pointed out because of machining problems such as delamination and burr phenomenons. Especially, hole machining process, drilling, has non-smooth features on inlet and outlet surfaces of drilled hole. This kind of machining problem can be controlled to some extent by using high modulus pitch-CF, which has considerable effects on fracture behavior of composite compared with only PAN CF composite. Therefore, PAN and pitch hybridized CF composites were prepared having high strength and modulus. The results demonstrate that the hybrid CFRP specimens with pitch CF offer the good potential to enhance modulus as well as strength properties. Dynamic mechanical, flexural, and impact properties were measured and analyzed. Morphological surface of the composites were also observed by IFS-28, canon after hole machining.

• Journal of Korean Neurosurgical Society
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• v.58 no.4
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• pp.397-400
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• 2015

The simultaneous occurrence of an intracranial and a spinal subdural hematoma (SDH) is rare. We describe a case of cranial SDH with a simultaneous spinal SDH. An 82-year-old woman visited the emergency room because of drowsiness and not being able to walk 6 weeks after falling down. A neurological examination showed a drowsy mentality. Brain computed tomography showed bilateral chronic SDH with an acute component. The patient underwent an emergency burr-hole trephination and hematoma removal. She exhibited good recovery after the operation. On the fourth postoperative day, she complained of low-back pain radiating to both lower limbs, and subjective weakness of the lower limbs. Spine magnetic resonance imaging revealed a thoracolumbosacral SDH. A follow-up spinal magnetic resonance imaging study that was performed 16 days later showed a significant decrease in the size of the spinal SDH. We discuss the pathogenesis of this simultaneous occurrence of spinal and cranial SDH.

• Journal of Korean Neurosurgical Society
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• v.53 no.2
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• pp.108-111
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• 2013

Burr hole drainage has been widely used to treat chronic subdural hematomas (SDH), and most of them are easily treated by simple trephination and drainage. However, various complications, such as, hematoma recurrence, infection, seizure, cerebral edema, tension pneumocephalus and failure of the brain to expand due to cerebro-cranial disproportion may develop after chronic SDH drainage. Among them, intracerebral hemorrhage after evacuation of a recurrent chronic SDH is very rare. Here, we report a fatal case of delayed intracerebral hemorrhage caused by coagulopathy following evacuation of a chronic SDH. Possible pathogenic mechanisms of this unfavorable complication are discussed and a review of pertinent literature is included.

• Journal of Korean Neurosurgical Society
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• v.41 no.1
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• pp.43-46
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• 2007

Hypoglossal neurilemmoma is extremely rare. Intracranial hypoglossal neurilemmoma has been reported to the present most commonly as a space-occupying lesion with symptoms of raised intracranial pressure. A 68-year-old women presented with deviation of the tongue to the left on protrusion. Preoperative radiological images revealed an extra-axial mass in and around the hypoglossal canal. The tumor was totally resected via retrosigmoid suboccipital approach with burrhole craniectomy. Histopathological examination verified a neurilemmoma. She had no neurologic abnormality except hypoglossal palsy which recovered completely in six months. Retrosigmoid suboccipital approach with burrhole craniectomy can be an useful approach in intracranial hypoglossal neurilemmoma without extracranial extension or with minimal extracranial extension into the hypoglossal canal.

• Journal of Korean Neurosurgical Society
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• v.53 no.3
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• pp.201-203
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• 2013

In most cases, subdural hematoma (SDH) is regarded as a complication of head injury and nontraumatic causes are rare. Moreover, spontaneous chronic SDH in child or adolescent is very unusual. Here, we present the case of a healthy 14-year-old girl who was diagnosed as a spontaneous chronic SDH. The patient presented with severe headache following blurring of vision two weeks ago without any history of trivial head injury. Computed tomography and magnetic resonance imaging depicted a chronic SDH. The cause of the hematoma was not established. After performing burr hole drainage of the hematoma, the patient made an uneventful recovery. We explore the potential risk factors and pathophysiology implicated in this condition. Possible pathogenic mechanisms of this unique case are discussed and a review of the pertinent literature is included.

• Journal of Korean Neurosurgical Society
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• v.58 no.2
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• pp.144-146
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• 2015

Postdural punctural headache (PDPH) following spinal anesthesia is due to intracranial hypotension caused by cerebrospinal fluid (CSF) leakage, and it is occasionally accompanied by an intracranial hematoma. To the best of our knowledge, an intracranial chronic subdural hematoma (CSDH) presenting with an intractable headache after a cervical epidural steroid injection (ESI) has not been reported. A 39-year-old woman without any history of trauma underwent a cervical ESI for a herniated nucleus pulposus at the C5-6 level. One month later, she presented with a severe headache that was not relieved by analgesic medication, which changed in character from being positional to non-positional during the preceding month. Brain magnetic resonance imaging revealed a CSDH along the left convexity. Emergency burr-hole drainage was performed and the headache abated. This report indicates that an intracranial CSDH should be considered a possible complication after ESI. In addition, the event of an intractable and changing PDPH after ESI suggests further evaluation for diagnosis of an intracranial hematoma.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.407-413
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• 2010

This paper reports on the research which analyzes acoustic signals acquired in progressive compressing, hole blanking, and burr compacting process. An acoustic sensor was set on the bed of hydraulic press. Acoustic signal is generated from progressive stamping process. First the signal acquired from the unit process; compressing, blanking or compacting, is studied by Fourier Transform and Short Time Fourier Transform. The blanking process emitted ultrasonic signal with more than 20kHz, but the compressing and compacting processes emitted acoustic signals with lower than 10kHz. The combined signals periodically acquired right after the tool grinding were then analyzed. 70-80kHz signals appeared in time-frequency domain, but not in the frequency domain, the magnitude of which was related to the tool wear. Short Time Fourier Transform made up for the Fourier Transform in analyzing the emitted signal for stamping process in the ultrasonic domain.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.3
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• pp.275-280
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• 2005

Recently there has been a growing interest in the design and manufacturing of the muffler tube due to the strict environment regulations, A muffler is an important part used to reduce noise and to purify exhaust gas in cars and heavy equipment. The shape of the muffler tube and the number of the tube hole has been made variously according to the weight and function of the car. The perforating technique of the muffler tube has a great influence on the manufacturing cost. In this study, metal forming analysis has been carried out to investigate the perforating process for the muffler tube and predict an optimal forming conditions of the muffler tube, Also its simulation results by the finite element method were reflected to the die design and the manufacturing system for the muffler tube. The perforating process is performed in the longitudinal direction of the tube. According to the simulation results, when the shear angle of punch was similar to the tube curvature, the optimal shape was obtained. Also when the clearance of die was 0.2mm, the burr was minimized and optimal shear section was obtained.

• Journal of Korean Neurosurgical Society
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• v.37 no.5
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• pp.386-388
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• 2005

The authors present a case in which an organized chronic subdural hematoma(CSDH) was incidentally found in a 9-year-old boy with no significant medical history after a pedestrian traffic accident. Preoperative magnetic resonance(MR) imaging showed calcification on the inner membrane and an irregular heterogeneous structure in the hematoma cavity. The findings from the preoperative brain computed tomogram(CT) and MR image were very useful for making the preoperative diagnosis and surgical decision. In choosing the proper surgical strategy for removing the organized CSDH, it was thought that burr hole trephination would present unnecessary difficulties. Thus, craniotomy was selected and the organized CSDH was successfully removed with no complications.

• Journal of Korean Neurosurgical Society
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• v.53 no.6
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• pp.380-382
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• 2013

We report a case of fatal duret hemorrhage (DH) in a patient with acute tentorial subdural hematoma and bilateral chronic subdural hematoma along the cerebral hemispheres. Preoperative CT angiography (CTA) revealed prominent parenchymal enhancement in the ventral pontomesencephalic area. After burr-hole drainage, a large hemorrhage developed in this area. The parenchymal enhancement in the CTA may reflect the pontomensencephalic perforating vessel injury, and may be a sign of impending DH of acute transtentorial downward herniation. Previous use of aspirin and warfarin might have potentiated the process of DH and increase the extent of the bleed.