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Development of high-performance and low-noise axial-flow fan units in their local operating region
차승헌,하민호,김태훈,정철웅 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.9
Aerodynamic and aeroacoustic performances of an axial-flow fan unit are improved by modifying its housing structure without changingthe fan blade. The target axial-flow fan system is used to lower temperature of a compressor and a condenser in the machine room ofa household refrigerator which has relatively high system resistance due to complex layout of structures inside it. First, the performanceof the fan system is experimentally characterized by measuring its volume flow rate versus static pressure using a fan performance testersatisfying the AMCA (Air Movement and Control Association) regulation, AMCA 210-07. The detailed structure of flow driven by thefan is numerically investigated using a virtual fan performance tester based on computational fluid dynamics techniques. The predictionresult reveals possible loss due to radial and tangential velocity components in the wake flow downstream of the fan. The length of thefan housing is chosen as a design parameter for improving the aerodynamic and aeroacoustic performances of the fan unit by reducingthe identified radial and tangential velocity components. Three fan units with different housing lengths longer than the original are analyzedusing the virtual fan performance tester. The results confirm the improved aerodynamic performance of the proposed three designs. The flow field driven by the proposed fan unit is closely examined to find the causes for the observed performance improvements, whichensures that the radial and tangential velocity components in the wake flow are reduced. Finally, the improved performance of the proposedfan systems is validated by comparing the P-Q and efficiency curves measured using the fan performance tester. The noise emissionfrom the household refrigerator is also found to be lessened when the new fan units are installed.
가토의 뇌대조내 자가용철 혈액 주입후 뇌연막혈관의 변화와 Nimodipine 정주의 영향
차승헌,장병조 대한신경외과학회 1995 Journal of Korean neurosurgical society Vol.24 No.3
The reactions of cerebral pial vessels following the injection of normal saline(0.05cc. at 37℃, pH7.4) and autogenous hemolytic blood(0.05cc, 0.1cc, 0.2cc) into the cisterna magna of rabbits were tasted in vivo. This experiment was performed in order to observe the effect of intravenous nimodipine(30㎍/kg) injection at the maximally constricted time of the pial vessels, about 6 hours after intracisternal injection of autogenous hemolytic blood. The diameter changes of the pial vessels were measured under operation microscope through a cranial window on craniectomized area. Pial vessels were not significantly changed after an intracisternal injection of normal saline. But after intracisternal injection of autogenous hemolytic blood(0.05cc, 0.1cc, 0.2cc), pial vessels were maximally constricted at 6 hours and the constriction was continued during the experiments. Percentile constriction was increased as the amount of subarachnoid hemolytic blood increased. According to the results, pial vessels, especially smally pial artery, were constricted by autogenous hemolytic blood containing oxyhemoglobin. Nimodipine, calcium antagonist, showed dilating effect on vasospasm after experimental subarachnoid hemorrhage with autogenous hemolytic blood in rabbits.
차승헌,송근성,박동준,장병조,이영우 대한신경외과학회 1995 Journal of Korean neurosurgical society Vol.24 No.1
Aneurysmal bone cysts are lytic lesions that have been described in virtually every portion of the skeleton but most commonly occur as solitary lesions in the metaphyseal portions of long bones. One fifth of aneurysmal bone cysts occur in the spine where they most frequently involve the posterior elements. In the spine, aneurysmal bone cyst have been reported to occur in the lower thoracic and lumbar regions, but their occurrence in the cervicodorsal area is uncommon. In this case, the second cervical vertebral body and posterior elements are affected. Fortunately, the lesion didn't invade into the spinal canal. The main symptom on admission was pressure pain, tenderness and motion limitation of the cervical spine. We removed the lesion involving posterior elements of second cervical spine and used horse-shoe shaped pediatric C-D device for occipito-cervical fixation. The clinical symptoms were resolved after operation. The clinical, radiologic, operative and pathological findings are reported and the corresponding literature are reviewed.
A Case of Large Foramen Magnum Schwannoma
전진호,차승헌,송근성,최창화 대한신경외과학회 2004 Journal of Korean neurosurgical society Vol.35 No.3
Most intracranial schwannomas originate from the cranial nerve especially CN V, VIII. However, schwannomas from low-cranial nerve are rarely reported. We report a case of large foramen magnum schwannoma in a 26 year-old-man presenting swallowing difficulty, nausea and vomiting. Magnetic resonance image revealed a cystic multilobulated huge mass from midclivus to atlas which compressed brain stem. The mass was removed by far-lateral transcondylar approach and confirmed with schwannoma which originated from hypoglossal nerve.
김병주,차승헌,박동준,송근성,최창화,이영우,Kim, Byung Joo,Cha, Seung Heon,Park, Dong June,Song, Geun Sung,Choi, Chang Hwa,Lee, Young Woo 대한신경외과학회 2000 Journal of Korean neurosurgical society Vol.29 No.2
Ventriculoperitoneal(V-P) shunt has been used as a popular method for surgical treatment of hydrocephalus. But complications such as infection, mechanical obstruction and failure of flow rate sometimes make painful stress to neurosurgeons and patients. Of particular, migration of distal V-P shunt catheter to extraperitoneal space has rarely been reported. Even rarer is intracardiac migration of distal V-P shunt catheter. Authors report a such case and discuss the possible mechanism and preventive method.
Spheno-Orbital Plasmacytoma as an Initial Presentation of Multiple Myeloma
안상준,차승헌,조원호 대한뇌종양학회 2022 Brain Tumor Research and Treatment Vol.10 No.4
Intracranial plasmacytoma is a rare neoplasm and a subtype of malignant plasma cell tumor. Most pa- tients with plasma cell tumors are diagnosed with multiple myeloma, but 5%–10% of patients are not. This report includes descriptions of radiologic and clinical findings in a patient with intracranial plasma- cytoma. Intracranial extra-axial plasmacytomas can be easily misdiagnosed as meningioma in radio- logic and clinical findings. A 69-year-old woman presented with exophthalmos and diplopia, and MRI indicated meningioma. Thus, she underwent gross total resection, and her pathologic diagnosis was plasmacytoma. Exophthalmos and diplopia were fully recovered. She was finally diagnosed with multi- ple myeloma based on systemic evaluation and treated with targeted chemotherapy. MRI conducted at 3 months after surgery showed no local recurrence or remnant tumor. Although intracranial plasma- cytomas are difficult to distinguish from meningiomas in preoperative evaluation, gross total resection is recommended for the same purposes as meningiomas. If the pathologic diagnosis is a plasmacyto- ma, it is essential to have a systemic evaluation for multiple myeloma.