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중이 질환에서 기계학습을 통한 Wideband Tympanometry의 유용성 분석
한승철,박해찬,변예진,서명환,이준호,오승하,박무균 대한이비인후과학회 2023 대한이비인후과학회지 두경부외과학 Vol.66 No.7
Background and Objectives Wideband tympanometry (WBT) provides information addi-tional to what can be provided by the relms of traditional tympanometry, such as absorbance,resonance frequency, and peak pressure. We investigated the characteristics of WBT in vari-ous middle ear disorders, especially for chronic otitis media (COM), otosclerosis, and patulouseustachian-tube disorder (ETD). Subjects and Method We recruited 165 patients who presented 179 normal ears and 151abnormal ears due to COM (113 ears), otosclerosis (14 ears) and ETD (24 ears). We analyzedpeak pressure and resonance frequency data using the Mann-Whitney test and absorbancedata using the machine learning modeling. Results The only significant difference in peak pressure and resonance frequency was ob-served in COM ears in contrast to normal ears. For absorbance data from WBT, we made 3models for machine learning to compare normal ears agaist COM, ETD, and all middle eardisorders. Models for otosclerosis ears and normal ears were impossible to analyze due to thesmall numbers of otosclerosis patients. Of the 3 models, the model comparing COM and nor-mal ears had only meaningful area under receiver operating characteristic results from leastabsolute shrinkage and selection operator analysis and Elastic Net analysis. Conclusion WBT could provide useful information for the diagnosis of various middle eardisorders, especially for chronic otitis media.
한승철,진성호,이재욱 한국고분자학회 2012 Macromolecular Research Vol.20 No.10
A synthetic strategy for dendrimers was developed using Staudinger/aza-Wittig reaction with an aldehyde and an azide in the presence of triphenylphosphine, followed by the reduction of imine intermediates. A fusion method between Fréchet-type dendritic benzaldehydes and Fréchet-type dendritic benzyl azides led to the formation of first-through fourth-generation dendrimers containing secondary amine as a connector in high yields. Further,fusion coupling using different generation dendrons afforded, efficiently, the unsymmetrical dendrimers. The obtained dendrimers were characterized by the analyses of 1H and 13C NMR spectroscopy, IR spectroscopy, mass spectra, and gel permeation chromatography (GPC) analysis.
디스크 브레이크에서 마찰열과 패드에 작용하는 융합 접촉거동에 관한 연구
한승철,이봉구 한국융합학회 2018 한국융합학회논문지 Vol.9 No.1
자동차 디스크 브레이크시스템에서는 열유속 및 열변형 등과 같은 이유로 마찰열이 균일하게 분산되지 않는다. 마찰열에 의한 열탄성 변형이 접촉압력 분포에 영향을 미치게 되고, 접촉하중이 디스크 브레이크 표면상의 작은 영역에 집중되어 열탄성 불안정성을 초래 할 수 있다. 본 연구에서는 실험적 계산식과 Kao 제안한 디스크와 패드의 접촉압력에 대한 해석방법을 참고로 하여 3차원 축대칭 모델을 통하여 실제로 제동 시 발생되는 디스크와 패드의 접촉을 고려한 온도 해석 및 열변형 해석을 하였다. ANSYS를 사용하여 디스크와 패드의 접촉면에서 발생하는 열탄성 불안전성 문제를 열하중과 기계적 하중으로 동시에 고려하여 해석하였다. 디스크와 패드가 직접 접촉하는 3차원 축대칭 모델을 구성하여 디스크의 마찰면 온도, 열변형, 접촉 열응력을 관찰함으로써 디스크에서 일어나는 열적 거동을 보다 정확하게 관찰하였다. In automotive disc brake systems, frictional heat is not uniformly dispersed for reasons such as heat flux and thermal deformation. The thermoelastic deformation due to the frictional heat affects the contact pressure distribution and the contact load may be concentrated on the contact portion on the the disc brake surface, resulting in thermoelastic instability. In this study, thermal analysis and thermal deformation analysis considering the contact between disk and pad occurred during braking through 3D axial symmetry model with reference to the experimental equation and Kao's analysis method of contact pressure of disk and pad. ANSYS is used to analyze the thermal and elastic instability problems occurring at the contact surface between the disk and the pad, considering both the thermal and mechanical loads. A 3D axisymmetric model with direct contact between the disk and the pad was constructed to more accurately observe the thermal behavior of the disk by observing the frictional surface temperature, thermal deformation and contact thermal stress of the disk.