• Journal of Audiology & Otology
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• 제25권4호
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• pp.230-234
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• 2021

Otosclerosis, a hereditary disorder characterized by disordered resorption and deposition of bone, results in progressive hearing loss. Osteogenesis imperfecta (OI) is a genetic disorder characterized by recurrent fractures, blue sclera, and varying degrees of hearing impairment; and is a known risk factor for otosclerosis. After adolescence, the risk of fracture decreases, reducing the need for follow-up in OI. However, otosclerosis is a progressive disorder. In this report, we discuss two cases of familial otosclerosis with different clinical features. We hypothesize that the difference in hearing level correlates with the difference in computed tomography findings. The mother, whose case was considered severe, was prescribed hearing aids, while the daughter, who had normal hearing level, was regularly followed up.

• 대한청각학회지
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• 제25권4호
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• pp.230-234
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• 2021

Otosclerosis, a hereditary disorder characterized by disordered resorption and deposition of bone, results in progressive hearing loss. Osteogenesis imperfecta (OI) is a genetic disorder characterized by recurrent fractures, blue sclera, and varying degrees of hearing impairment; and is a known risk factor for otosclerosis. After adolescence, the risk of fracture decreases, reducing the need for follow-up in OI. However, otosclerosis is a progressive disorder. In this report, we discuss two cases of familial otosclerosis with different clinical features. We hypothesize that the difference in hearing level correlates with the difference in computed tomography findings. The mother, whose case was considered severe, was prescribed hearing aids, while the daughter, who had normal hearing level, was regularly followed up.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• 제56권12호
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• pp.749-753
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• 2013

Basically stem cells have characteristics of multi-potency, differentiation into multiple tissue types, and self-renew through proliferation. Recent advances in stem cell biology can make identifying the stem-cell like cells in various mammalian tissues. Stem cells in various tissues can restore damaged tissue. Stem cells from the adult nervous system proliferate to form clonal floating colonies called spheres in vitro, and recent studies have demonstrated sphere formation by cells in the tympanic membrane, vestibular system, spiral ganglion, and partly in the organ of Corti. The presence of stem cells in the ear raises the possibilities for the regeneration of the tympanic membrane & inner ear hair cells & neurons. But the gradual loss of stem cells postnatally in the organ of Corti may correlate with the loss of regenerative capacity and limited hearing restoration. Future strategies using endogenous stem cells in the ear can be the another treatment modality for the patients with intractable inner ear diseases.

• 상하수도학회지
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• 제23권2호
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• pp.215-222
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• 2009

This study compares the performance of the filters with various media in pretreatment of seawater desalination by reverse osmosis. For this purpose, Masan bay seawater is used as raw water. The filter performance is evaluated by the filtrate quality and the head loss development. Five media is selected in this study: anthracite, $Filtralite^{(R)}$, sand, Pumice, $AFM^{(R)}$. These media are used in combination for dual media filter and alone for mono media filter. The comparison results show that NC0.8-1.6 is the best $Filtralite^{(R)}$. The dual media filter of NC0.8-1.6 and sand outperformed other filters in particle removal. The dual media filter of anthracite and sand showed good performance in organic removal. The mono media filter of Pumice produced the similar filtrate quality as the mono media filter of sand although the effective size of Pumice is considerably greater than that of sand. Due to big size, head loss development is maintained slow in the filtration of Pumice.

• Geomechanics and Engineering
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• 제33권5호
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• pp.463-475
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• 2023

Tunnel construction activity, conducted mainly in mountains and within urban centres, causes soil settlement, thus requiring the relevant management of slopes and structures as well as evaluations of risk and stability. Accordingly, in this study we performed a three-dimensional finite element analysis to examine the behaviour of piles and pile cap stability when a tunnel passes near the bottom of the foundation of a pile group connected by a pile cap. We examined the results via numerical analysis considering different conditions for reinforcement of the ground between the tunnel and the pile foundation. The numerical analysis assessed the angular distortion of the pile cap, pile settlement, axial force, shear stress, relative displacement, and volume loss due to tunnel excavation, and pile cap stability was evaluated based on Son and Cording's evaluation criterion for damage to adjacent structures. The pile located closest to the tunnel under the condition of no ground reinforcement exhibited pile head settlement approximately 70% greater than that of the pile located farthest from the tunnel under the condition of greatest ground reinforcement. Additionally, pile head settlement was greatest when the largest volume loss occurred, being approximately 18% greater than pile head settlement under the condition having the smallest volume loss. This paper closely examines the main factors influencing the behaviour of a pile group connected by a pile cap for three ground reinforcement conditions and presents an evaluation of pile cap stability.

• Annals of Clinical Neurophysiology
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• 제1권1호
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• pp.64-69
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• 1999

Background : Syncope was defined as transient loss of consciousness and postural tone. The mechanisms of changes in cerebral hemodynamics during syncope have not been fully evaluated. Transcranial Doppler Ultrasonography can continuously monitor the changes in cerebral hemodynamics during head-up tilt (HUT). TCD could reveal the different patterns of changes in cerebral hemodynamics during syncope. Syncope without hypotension or bradycardia could be detected by TCD. We investigated the changes in cerebral blood flow velocity during HUT using TCD in 33 patients with a history of recurrent syncope or presyncope of unknown origin. Methods & Results : The positive responses were defined as presyncope or syncope with hypotension, bradycardia, or both. During HUT without isoproterenol infusion, there were a $86{\pm}23%$ drop in DV and a $41{\pm}34%$ drop in SV in 5 patients with positive reponses, and mean changes in those were less than 10% in patients with negative reponses (p=.00, p=.00). During HUT with isoproterenol infusion, TCD showed a $80{\pm}18%$ drop in diastolic velocity in 14 patients with positive reponses, and a $47{\pm}10%$ drop in that in patients with negative reponses (p=.00), however the change in systolic velocity did not differ. TCD showed three patterns during positive responses; loss of all flow, loss of end diastolic flow, and a decrease in diastolic velocity. Loss of consciousness occurred in the patients with loss of all flow or end-diastolic flow during positive reponses. Conclusions : TCD shows different patterns of changes in cerebral hemodynamics during HUT. TCD can be used to investigate the pathophysiology of neurocardiogenic syncope.

• 한국자동차공학회논문집
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• 제5권6호
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• pp.103-110
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• 1997

A performance prediction method is presented for single(double) suction centrifugal pumps with a review of loss correlations given in the previous open literature. Most of the loss analyses mentioned in the present study are one dimensional and this paper investigates several modeling schemes and shows that a fairly good prediction can be achieved by a proper selection of the most important flow parameters resulting from a mean streamline analysis. Predictions of the trends of total head- capacity and pump efficiency-capacity curves agree well with the experimental data in almost the full range of operating conditions. The prediction method developed through this study can serve as a tool to ensure good matching between parts and it can assist the understanding of the operational characteristics of general purpose centrifugal pumps.

• 대한청각학회지
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• 제23권1호
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• pp.59-62
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• 2019

Primary tumors arising from the external auditory canal (EAC) are rare. We describe two cases of mass lesions within the EAC causing slowly progressive hearing loss without otorrhea or otalgia. Otoendoscopic examination demonstrated total obstruction of the EAC, and pure tone audiometry revealed conductive hearing loss. Based on the findings of the histopathologic examination, one patient was diagnosed with venous hemangioma that was treated using surgical resection, and the other patient was diagnosed with diffuse large B-cell lymphoma (DLBCL) that was treated using external-beam radiation therapy. Although primary tumors in the EAC are rare, both benign tumors such as venous hemangiomas and malignant lesions such as DLBCL should be considered as possible differential diagnoses of mass lesions in the EAC.

• Journal of Audiology & Otology
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• 제23권1호
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• pp.59-62
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• 2019

Primary tumors arising from the external auditory canal (EAC) are rare. We describe two cases of mass lesions within the EAC causing slowly progressive hearing loss without otorrhea or otalgia. Otoendoscopic examination demonstrated total obstruction of the EAC, and pure tone audiometry revealed conductive hearing loss. Based on the findings of the histopathologic examination, one patient was diagnosed with venous hemangioma that was treated using surgical resection, and the other patient was diagnosed with diffuse large B-cell lymphoma (DLBCL) that was treated using external-beam radiation therapy. Although primary tumors in the EAC are rare, both benign tumors such as venous hemangiomas and malignant lesions such as DLBCL should be considered as possible differential diagnoses of mass lesions in the EAC.

• 한국해안·해양공학회논문집
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• 제26권6호
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• pp.343-351
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• 2014

유공벽에 의한 파의 반사율과 투과율은 주로 유공벽의 공극률과 벽두께 그리고 입사파의 주기 및 비선형성에 의해 결정된다. 이중에서 벽두께는 유공벽의 수두손실계수와 관성저항길이에 영향을 미치므로 매우 중요하다. 그러나 기존의 연구에서는 예연 오리피스의 수두손실계수를 사용함으로써 수두손실계수에 미치는 벽두께 효과를 무시 또는 부정확하게 고려하였거나, 벽두께가 수두손실계수에 미치는 영향은 고려하였더라도 관성저항 길이를 무시함으로써 벽두께가 유공벽의 반사율과 투과율에 미치는 영향이 적절히 고려되지 못 하였다. 따라서 본 연구에서는 다양한 두께의 유공벽을 제작하여 파의 반사율 및 투과율 측정 수리실험을 수행하였으며, 그 결과를 기존의 해석해에 의한 값과 비교하였다. 비교결과 기존의 해석해 들이 벽두께의 효과를 적절히 반영하지 못하고 있음을 확인하였으며, 벽두께 효과를 정도 높게 고려할 수 있는 새로운 수두손실계수 산정식이 필요함을 확인하였다.