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포스터 전시 : 위장관 ; 상행경잘을 침범한 제 1형 신경섬유종증 1예
변태준 ( T. J. Byun ),이오영 ( O. Y. Lee ),이홍우 ( H. W. Lee ),임현철 ( H. C. Rhim ),은창수 ( C. S. Eun ),박준용 ( J. Y. Park ),이승환 ( S. H. Lee ),한동수 ( D. S. Han ),전용철 ( Y. C. Jeon ),윤병철 ( B. C. Yoon ),박문향 ( M. H. Par 대한소화기학회 2002 대한소화기학회 춘계학술대회 Vol.2002 No.-
<서론> 신경섬유종증은 전신 장기를 침범하는 유전성 질환으로 다수의 밀크 커피색 반점과 신경섬유종을 특징으로 한다. 총상(plexiform) 신경섬유종증은 제 1형 신경섬유종증 진단에 특징적인 소견이고, 체간의 다양한 부위에서 관찰된다. 횡격막 아래에서는 주로 후복막강(retroperitoneal space)과 척추주변에서 발생되고 장과 장간막은 침범은 드물다. 저자들은 제 1형 신경섬유종증에서 총상 신경섬유종증의 상행결장의 침범의 증례가 있어 보고하는
이홍우(H. W. Lee) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
In sheet metal forming process, friction between sheet and tool plays an important role. The frictional behavior depends on local contact conditions such as local surface roughness profile, normal load and sliding speed. In case of steel sheets, rough surfaces are always generated in the roll process with the different types of texturing. Therefore, to understand the friction behavior in steel sheets, it is very important to consider the surface roughness profile. Many types of friction models have been reported in order to explain the role of 3-D surface topography. Recently, the mechanical-rheological friction model explains well the tribological characteristics of 3-D surface profile. In this paper, the friction behavior of steel sheets is investigated with the mechanical-rheological model based on mixed lubrication regime. For more accurate analysis, numerical rough contact analysis under lubricated condition is applied. From numerical contact analysis, contact, hydrostatic and hydrodynamic pressures can be obtained. And rotational friction test is applied in order to evaluate practical friction coefficients in forming process. The frictional behavior under lubricated conditions could be explained more suitably from the results.
Wi-Fi Backscatter Systems for IoT Sensors with Enhanced Communication Reliability
김찬규(Chankyu Kim),백성민(Seongmin Baek),이성주(Seongjoo Lee) 대한전자공학회 2020 대한전자공학회 학술대회 Vol.2020 No.8
IoT 기술이 발전함에 따라 배터리 문제가 대두되었다. 미국의 워싱턴 대학에서 저전력으로 Tag를 동작시키는 Wi-Fi 백스케터 기술을 처음 제시하였다. 그러나 이 방식은 전송 성능 및 전송률이 낮다는 단점이 있었다. 이를 개선하기 위해 Tag에서 에너지를 조절하는 M-레벨 변조 방식을 통해 전송률을 높이는 방법이 제시되었다. 그러나 M-레벨 변조 방식은 낮은 SNR환경에서 신뢰성이 떨어지는 문제점이 있었다. 본 논문에서는 딥러닝 기반의 수신기를 구성함으로써 낮은 SNR 환경에서도 Wi-Fi backscatter 시스템의 성능을 높일 수 있도록 하였다. 또한, Tag의 구성을 그대로 적용하기 때문에 전송률뿐 아니라 Tag에서 배터리가 필요하지 않으며, 사용되는 에너지가 적다는 장점도 있다. 제안하는 딥러닝 방식은 2-level일 때 22dB SNR 환경에서 10-3 BER 성능을 확인하였다.
하세윤(S. Y. Ha),이홍우(H. W. Lee),조진래(J. R. Cho),박태학(T. H. Park),이우용(W. Y. Lee) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.10
This paper deals with the analytic and FEM analysis of sloshing frequency response for incompressible, invicid and irrotational flow in two dimensional rectangular tank. We use Laplace equation based on potential theory as governing equation. For small amplitude sloshing motion, the linearized free surface condition was applied and the solution was calculated by the separation of variables. To avoid the divergence of response at resonance frequencies, artificial damping is introduced. Also, this problem was solved by FEM using 9-node elements in orther to compare with the analytical solution.
김현옥(H. O. Kim),이홍우(H. W. Lee),조진래(J. R. Cho),이진규(J. K. Lee),장문석(M. S. Jang) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.10
In the process of HSU design, decision of kinematic dimension is important part. At first, we put in order kinematic relationship of HSU and so show coherent course in the kinematic design. And by using of decided dimension data, we analyze kinematic motion and investigate dynamic characteristics of moving part of HSU systems.
이홍우(H.W.Lee),조진래(J.R.Cho),이진규(J.K.Lee),장문석(M.S.Chang),안동수(D.S.Ahn) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
In this paper we discuss the dynamic characteristics of the in-am1 type hydropneumatic suspension unit(ISU). For this, two accurate models are introduced. The first one is the Benedict-Webb-Rubin equation which is adopted for the spring behavior of a real gas. This equation is applicable for the high pressure of the nitrogen gas which acts as a spring in ISU system. The second one describes the behavior of a damper. which is divided into four parts - jounce-loading. jounce-unloading. rebound-loading and rebound-unloading. This approach gives a good approximation of the real damper system. For the comparison purpose. the numerical results of the dynamic behavior of ISU system using a real gas and an ideal gas are given in the paper.
이홍우(H. W. Lee),하세윤(S. Y. Ha),조진래(J. R. Cho),박태학(T. H. Park),이우용(W. Y. Lee) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.4
This paper deals with the FEM analysis for Nonlinear sloshing of incompressible, invicid and irrotational flow in two dimensional rectangular tank. We use Laplace equation based on potential theory as governing equation. For large amplitude sloshing motion, kinematic and dynamic free surface conditions derived from Bernoulli equation are applied. This problem is solved by FEM using 9-node elements. For the time integration and accurate velocity calculation, we introduce a predictor-corrector time marching scheme and least square method. Also, numerical stability in tracking of free surface is obtained by direct calculation of free surface location to time variation. Numerical results of sloshing induced by harmonic excitations, while comparing with those of linear theory and references, prove the accuracy and stability. After verification of our program, we analyze sloshing response characteristics to the fluid height and the excitation amplitude.