• Journal of Advanced Marine Engineering and Technology
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• v.9 no.2
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• pp.159-169
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• 1985

The calculation of torsional vibration for marine diesel engine propulsion shafting is normally carried out by equalizing exciting energy to damping energy, or using the dynamic magnifier. But, with these methods, the vibration amplitudes are calculated only for resonance points and vibration amplitudes of other running speeds of engine are determined by the estimation. Recently, many energy-saving ships have been built and on these ships, two-stroke, supercharged, super-long stroke diesel engines which have a small number of cylinders are usually installed. In these cases, the first order critical-torsional vibrations of these engine shaftings appear ordinarily near the MCR speed and the stress amplitudes of their vibration skirts exceed the limit stress defined by the rules of classification society. To predict the above condition in the design stage, the synthesized vibration amplitudes of all orders which are summed up according to their phase angles must be calculated from the drawings of propulsion shaft systems. In this study, a theoretical method to fulfill the above calculation is derived and a computer program is developed according to the derived method. And a shafting system of two-stroke, super-long stroke diesel engine which was installed in a bulk carrier is analyzed with this method. The measured values of this engine shafting are compared with those of calculated results and they show a fairly good agreement.

• Journal of Korean Neurosurgical Society
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• v.46 no.2
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• pp.172-175
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• 2009

We describe a case of 36-year-old man who presented with a subacute headache preceded by a 1-month history of posterior neck pain without trauma history. Head and neck magnetic resonance imaging (MRI) studies disclosed bilateral supratentorial subdural and retroclival extradural hematomas associated with marked cervical epidural venous engorgement. Cerebral and spinal angiography disclosed no abnormalities except dilated cervical epidural veins. We performed serial follow-up MRI studied to monitor his condition. Patient's symptoms improved gradually. Serial radiologic studies revealed gradual resolution of pathologic findings. A 3-month follow-up MRI study of the brain and cervical spine revealed complete resolution of the retroclival extradural hematoma, disappearance of the cervical epidural venous engorgement, and partial resolution of the bilateral supratentorial subdural hematoma. Complete resolution of the bilateral supratentorial subdural hematoma was confirmed on a 5-month follow-up brain MRI. The diagnosis and possible mechanisms of this rare association are discussed.

• Journal of Korean Neurosurgical Society
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• v.44 no.1
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• pp.47-51
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• 2008

Ligamentum flavum hematoma is a rare condition. Twenty cases including present case have been reported in English-language literature. Among them, only one case reported in pure thoracic spine. A 72-year-old man presented with thoracic myelopathy without precedent cause. Magnetic resonance images revealed a posterior semicircular mass which was located in T7 and T8 level compressing the spinal cord dorsally. T7-8 total laminectomy and extirpation of the mass was performed. One month later following surgery, the patient fully recovered to normal state. Pathologic result was confirmed as ligamentum flavum hematoma. Ligamentum flavum hematoma of rigid thoracic spine is a very rare disease entity. Most reported cases were confined to mobile cervical and lumbar spine. Surgeons should be aware that there seems to be another different pathogenesis other than previously reported cases of mobile cervical and lumbar spine.

• Journal of Korean Neurosurgical Society
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• v.53 no.5
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• pp.305-308
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• 2013

Myositis ossificans (MO) is a benign condition of non-neoplastic heterotopic bone formation in the muscle or soft tissue. Trauma plays a role in the development of MO, thus, non-traumatic MO is very rare. Although MO may occur anywhere in the body, it is rarely seen in the lumbosacral paravertebral muscle (PVM). Herein, we report a case of non-traumatic MO in the lumbosacral PVM. A 42-year-old man with no history of trauma was referred to our hospital for pain in the low back, left buttock, and left thigh. On physical examination, a slightly tender, hard, and fixed mass was palpated in the left lumbosacral PVM. Computed tomography showed a calcified mass within the left lumbosacral PVM. Magnetic resonance imaging (MRI) showed heterogeneous high signal intensity in T1- and T2-weighted image, and no enhancement of the mass was found in the postcontrast T1-weighted MRI. The lack of typical imaging features required an open biopsy, and MO was confirmed. MO should be considered in the differential diagnosis when the imaging findings show a mass involving PVM. When it is difficult to distinguish MO from soft tissue or bone malignancy by radiology, it is necessary to perform a biopsy to confirm the diagnosis.

• Journal of Korean Neurosurgical Society
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• v.60 no.3
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• pp.380-384
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• 2017

Glioblastoma multiforme (GBM) is located most frequently in the cerebral hemispheres. Glioblastoma presenting as an extraaxial mass of cerebellopontine angle (CPA) is very rare in adults. We report a rare case of GBM arising in the CPA. The patient was a 71-year-old female, who complained of progressive gait disturbance and poor memory. Initial magnetic resonance imaging (MRI) revealed a $1.4{\times}1.3cm$ mass in the left CPA, with broad base to the petrous bone, showing homogenous enhancement. Follow-up MRI showed a rapid increase in size of mass ($2.7{\times}2.2cm$) with a necrotic portion. A stereotactic biopsy was done under the guidance of navigation system, and the histopathologic diagnosis was GBM, World Heath Organization grade IV. Further surgical resection was not performed considering her general condition, and the patient underwent concurrent chemotherapy with radiation therapy. Although rare, the possibility of glioblastoma should be included in the differential diagnosis of atypical CPA tumor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.171-176
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• 2011

The purposes of the research were to evaluate system performance and response of building structure under external load for full scale modal-testing-tower applied toggle bracing and lead rubber damper(LRD). The dynamic properties of the structure were measured before and after installing damper under harmonic excitation using the AMD and the results were compared. The harmonic excitation condition is to increase 0.01Hz sine sweep signal from 0.49Hz to 0.63Hz. As a result of measuring resonant frequency, before installing damper is 0.55Hz and after installing damper is 0.62Hz. The experimental results after installing damper were also distinguished from simulation results and the main cause of this results is temperature dependency property of rubber material.

• Rapid Communication in Photoscience
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• v.2 no.3
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• pp.79-81
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• 2013

A novel method of fabricating polythiophene-gold nanoparticle composite film electrodes for photoelectric conversion is demonstrated. The method includes electrodeposition of gold and electropolymerization of 2,2'-bithiophene onto an indium-tin-oxide (ITO) electrode. First, electrodeposition of gold onto the ITO electrode was carried out with various repetition times of pulsed applied potential (0.25 s at -2.0 V vs. Ag/AgCl) in an aqueous solution of $HAuCl_4$. Significant progress of the number density of deposited gold nanoparticles was confirmed from scanning electron micrographs, from 4 (1 time) to 25% (15 times). Next, electropolymerization of 2,2'-bithiophene onto the above ITO electrode was performed under controlled charge condition (+1.4 V vs. Ag wire, 15 $mC/cm^2$). Structural characterization of as-fabricated films were carried out by spectroscopic and electron micrographic methods. Photocurrent responses from the sample film electrodes were investigated in the presence of electron acceptors (methyl viologen and oxygen). Photocurrent intensities increased with increasing the density of deposited gold nanoparticles up to ~10%, and tended to decrease above it. It suggests that the surplus gold nanoparticles exhibit quenching effects rather than enhancement effects based on localized electric fields induced by surface plasmon resonance of the deposited gold nanoparticles.

• Korean Journal of Head & Neck Oncology
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• v.27 no.1
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• pp.66-69
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• 2011

Skull base osteoradionecrosis(ORN)is a rare complication of radiotherapy for nasopharyngeal carcinoma, but is one of the most severe and possibly fatal condition followed by radiotherapy. However, the treatment of skull base ORN has seldom been thoroughly described yet. Here we report a case of skull base ORN that was successfully treated with hyperbaric oxygen therapy(HBO). A 52-year-old man visited our department complaining of trismus and foul odor. He was diagnosed with nasopharyngeal cancer with multiple lymph node metastasis one year ago and underwent concurrent chemoradiotherapy. On the physical examination, mucopus and crusts with exposed necrotic bone was seen in the right nasopharynx. On the paranasal sinus magnetic resonance imaging, osteoradionecrosis which was extending from the right nasopharynx to the clivus, petrous apex, and cavernous sinus was noted. Nasopharynx biopsy resulted of ulcer with no malignant cells. HBO therapy was performed with debridement of nasopharynx for 3 months. There was no sign of recurrence or residual ORN 18 months after HBO therapy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.110-113
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• 2006

This paper describes the development process of body and full vehicle for reduced idle vibration through the data level of frequency and sensitivity. The vibration mode map is used to separate body structure modes from resonance of engine idle nm and steering system. This paper describes the analysis approach process to reduce the variation of uncertainties for idle vibration performance at initial design stage. The robust design method is performed to increase the stabilization performance under vehicle vibration. It is used to predict the effects of the stiffness deviation according to the spot welding condition of the body structure. The tolerance associated with hood over slam bumper is analyzed for the quality deviation of the moving system in full vehicle. And the glass sealant stiffness and weight difference is considered for the deviation characteristic. The design guideline is suggested considering sensitivity about body and full vehicle by using mother car at initial design stage. It makes possible to design the good NVH performance and save vehicles to be used in tests. These improvements can lead to shortening the time needed to develop better vehicles.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1290-1295
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• 2006

The 120 meters high pressure feedwater heater drain piping in nuclear power plant had been suffered by excessive vibration from the beginning of power generation. As time goes by, the piping vibration was beyond the allowable limit and an appropriate countermeasure was required to prevent the fatigue failure of the pipeline from the abnormal vibration. In this study, the vibrational characteristics of high pressure feedwater heater drain piping and the countermeasure for abnormal vibration were investigated. Among the several vibration reduction methods, the piping layout changed by making the smooth pipeline was applied to the high Pressure feedwater heater drain piping in nuclear Power plant. Applying the countermeasure, the vibration level was found to reduce over 54 percents and was satisfied under the allowable velocity at the full-power operation condition.