• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2026-2031
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• 2007

Hydrogen is receiving much research attention as an alternative substitute for hydrocarbon fuels these days due to its cleanliness and renewability. However, hydrogen should be used with caution because of its high propensity for leak and wide flammable range. This study deals with a situation that hydrogen leaks and then forms a flammable mixture inside 1kW class residential fuel cell. The residential fuel cell was modeled as a box-shaped chamber with vent openings at the top and bottom, filled with various components such as reformer, desulfurizer, fuel cell stack and humidifier. Computational fluid dynamics (CFD) was used to simulate the diffusion, buoyant flow and accumulation of leaked hydrogen in the modeled chamber. From the simulation, the risk region vulnerable to flame was identified and the methods to minimize such hazardous region was discussed. When the vent openings are 1% of the total surface, as the quantity of hydrogen leakage increases the risk regions increases accordingly. As the vent openings of the total surface increased from 1% to 2.3%, averaged hydrogen mole fraction is under 1% in the system.

• Journal of Korean Neurosurgical Society
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• 제45권1호
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• pp.1-4
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• 2009

Objective : In the present study, the authors investigated the clinical and imaging features as well as the therapeutic outcomes of SIH (spontaneous intracranial hypotension) patients. Methods : A retrospective review of 12 SIH patients was carried out. The diagnostic work-up included lumbar tapping and measurement of CSF opening pressure, radioisotope cisternography, brain and spinal magnetic resonance imaging (MRI), and computed tomography (CT) myelography. Autologous epidural blood patching was performed in patients who did not respond to conservative therapies, including analgesics, steroids, hydration and rest. Results : Typical postural headache was found in 11 (91%) patients. Nine (75%) patients showed pachymeningeal enhancement on their initial T1-weighted MR images. The CSF opening pressure was less than 60 mm$H_2O$ in 9 of 11 patients. Autologous epidural blood patching was performed in 7 patients, and all of them showed good responses. Conclusion : SIH can present with various clinical presentations and neuroimaging findings. Autologous epidural blood patching is thought to be the treatment of choice for patients with SIH.

• Journal of Korean Neurosurgical Society
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• 제59권1호
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• pp.69-74
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• 2016

Chronic subdural hematoma (SDH) is a well-known disease entity and is traditionally managed with surgery. However, when associated with spontaneous intracranial hypotension (SIH), the treatment strategy ought to be modified, as classical treatment could lead to unwanted consequences. A 59-year-old man presented with a case of SIH that manifested as a bilateral chronic SDH. He developed fatal extensive pneumocephalus and SDH re-accumulation as a complication of burr-hole drainage. Despite application of an epidural blood patch, the spinal cerebrospinal fluid leak continued, which required open spinal surgery. Chronic SDH management should not be overlooked, especially if the exact cause has not been determined. When chronic SDH assumed to be associated with SIH, the neurosurgeon should determine the exact cause of SIH in order to effectively correct the cause.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.188-191
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• 2007

This paper shows the Development of In-tank pressure regulator and Solenoid Valve used in FCV(Fuel Cell Vehicle). We have developed new type of Regulator and Solenoid through analysis of the structure and characteristics of component of FCS(Fuel Cell System) from the advanced technology. Now it is possible to localize the component by making use of the development of Regulator and Solenoid made by us. Regulator and Solenoid is a equipment to control hydrogen pressure supplied into a stack. Therefore, outlet pressure, a flow of fluid and temperature are important parameters according to a inlet pressure. And leak test, endurance test and burst test should be done to guarantee the performance and safety of Regulator and Solenoid used in the fuel of high pressure. Also, Hydrogen friendly materials are applied to inner parts of the Regulator, Solenoid and weight reduction is done to cost saving in part not related to performance. As a result, we have proven the good performance and reliability in endurance of Regulator, Solenoid and will make an development in performance as well as durability to ensure industrialization.

• 대한두개안면성형외과학회지
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• 제16권2호
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• pp.80-83
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• 2015

We present reconstruction of a complicated scalp-dura defect using acellular human dermis and latissimus dorsi myocutaneous free flap. A 62-year-old female had previously undergone decompressive craniectomy for intracranial hemorrhage. The cranial bone flap was cryopreserved and restored to the original location subsequently, but necessitated removal for a methicillin-resistant Staphylococcal infection. However, the infectious nidus remained in a dermal substitute that was left over the cerebrum. Upon re-exploration, this material was removed, and frank pus was observed in the deep space just over the arachnoid layer. This was carefully irrigated, and the dural defect was closed with acellular dermal matrix in a watertight manner. The remaining scalp defect was covered using a free latissimus dorsi flap with anastomosis between the thoracodorsal and deep temporal arteries. The wound healed well without complications, and the scalp remained intact without any evidence of cerebrospinal fluid leak or continued infection.

• Journal of Korean Neurosurgical Society
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• 제45권5호
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• pp.318-321
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• 2009

Tension pneumocephalus may follow a cerebrospinal fluid(CSF) leak communicating with extensive extradural air. However, it rarely occurs after diagnostic lumbar puncture, and its treatment and pathophysiology are uncertain. Tension pneumocephalus can develop even after diagnostic lumbar puncture in a special condition. This extremely rare condition and underlying pathophysiology will be presented and discussed. The authors report the case of a 44-year-old man with a basal skull fracture accompanied by pneumothorax necessitating chest tube suction drainage, who underwent an uneventful lumbar tapping that was complicated by postprocedural tension pneumocephalus resulting in an altered mental status. The patient was managed by burr hole trephination and saline infusion following chest tube disengagement. He recovered well with no neurologic deficits after the operation, and a follow-up computed tomography (CT) scan demonstrated that the pneumocephalus had completely resolved. Tension pneumocephalus is a rare but serious complication of lumbar puncture in patients with basal skull fractures accompanied by pneumothorax, which requires continuous chest tube drainage. Thus, when there is a need for lumbar tapping in these patients, it should be performed after the negative pressure is disengaged.

• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.515-520
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• 2004

We report on the development of a Piezoelectric valvc that is designed to have a high reliability for fluid control systems, such as mass flow control, transportation and chemical analysis. The valve was fabricated using a MCA(multilayer ceramic actuator), which has a low consumption power, high resolution and accurate control. The fabricated valve is composed of MCA, a valve actuator die and an seat die. The design of the actuator dic was done by FEM(finite element method) modeling, respectively. And, the valve seat die with 6 trenches was made. and the actuator die, which possible to optimize control to MCA, was fabricated. After Si-wafer direct bonding between the seat die and the actuator die, MCA was also anodic bonded to the scat/actuator die structure. PDMS(poly dimethylsiloxane) sealing pad was fabricated to minimize a leak-rate. It was also bonded to scat die and stainless steel package. The flow rate was 9.13 sccm at a supplied voltage of 100 V with a 50 % duty ratio and non-linearity was 2.24 % FS. From these results, the fabricated MCA valve is suitable for a variety of flow control equipments, a medical bio-system, semiconductor fabrication process, automobile and air transportation industry with low cost, batch recess and mass production.

• 한국재난정보학회:학술대회논문집
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• 한국재난정보학회 2017년 정기학술대회
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• pp.339-340
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• 2017

화학공장의 누출사고는 초기에 적절히 대응하지 못할 경우 화재 폭발과 같은 2차 3차의 복합재난사고로 확산될 위험성이 매우 높다. 이러한 이유로 누출사고 발생 초기에 누출이 발생한 지점을 신속히 파악하여 현장안전요원에게 알림으로써, 보다 체계적이고 효율적인 초기대응을 가능하게 하여, 사고피해를 완화시킬 수 있는 통합적인 누출사고 대응시스템 구축은 매우 중요하다고 할 수 있다. 본 연구에서는, 통합적인 누출사고 대응시스템 구축을 위한 선행연구로, 딥러닝 기반의 누출원추적 모델 개발을 제안한다. 여수에 위치한 실제 화학공장을 대상으로 누출사고 시나리오에 대한 Computational Fluid Dynamics (CFD) 시뮬레이션을 진행한 뒤, 화학공장 경계면에 배치된 각 센서별 위치에서의 농도, 풍향 그리고 풍속데이터를 추출하고, 센서 좌표를 추가하여 인공신경망을 학습시켰다. 학습된 모델은 40개의 누출후보군에 대해 학습에 사용되지 않은 상황들에서도 75.43%의 정확도로 누출이 일어난 지점을 실시간 예측해냄을 확인하였다. 또한 누출지점 예측이 일치하지 않은 경우도, 예측된 지점이 실제 누출이 일어난 지점과 물리적으로 매우 인접함을 확인함으로써 제안된 모델을 실제 현장에 적용할시 기대되는 효과는 더 클 것으로 판단하였다.

• Journal of Chest Surgery
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• 제44권5호
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• pp.377-379
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• 2011

Chylopericardium is a rare disease entity characterized by the accumulation of chylous fluid in the pericardial sac. It usually arises from mediastinal neoplasms, thrombosis of the subclavian vein, tuberculosis, nonsurgical trauma, thoracic or cardiac surgery. The spectrum of symptoms for chylopericardium varies from an incidental finding of cardiomegaly to dyspnea, upper abdominal discomfort, cough, chest pain, palpitation, fatigue. However, most of the patients are asymptomatic. The main purpose of treatment of chylopericardium is the prevention of cardiac tamponade and prevention of metabolic, nutritional, and immunological compromise due to chyle leak. Here, we report a case of chylopercardium secondary to lymphangiomyoma with review of the literature.

• Research in Vestibular Science
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• 제17권4호
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• pp.170-174
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• 2018

Epidural anesthesia has significantly advanced in neuraxial anesthesia and analgesia. It is used for surgical anaesthesia and treatment of chronic pain. Hearing loss during or after epidural anesthesia is rare, and it is known to occur by the change of the intracranial pressure. Cerebrospinal fluid is connected with perilymph in the cochlear and vestibule that is important to hearing and balance. If the intracranial pressure is abruptly transferred to the inner ear, perilymph can be leak, that called perilymphatic fistula, dizziness, and hearing loss can occur suddenly. We report a 65-year-old woman who presented with acute onset dizziness and hearing loss during the epidural nerve block for back pain, wherein we speculated a possibility of perilymphatic fistula as the mechanism of hearing loss and dizziness. The mechanism of dizziness and hearing loss was suspected with perilymphatic fistula.