Yi Wang Biomedical Engineering, Cornell University

Contact : Jin Keun Seo

Aug. 3, 2016 - Aug. 5, 2016

참석자: Yi Wang (코넬대학교수), 우응제(경희대학교), 서진근, 주량동

내용: Quantitative susceptibility mapping에서 wavefornt와 같은 영상왜곡이 일어나는 수학적 근거에 대해 논의함. 수리모델이 파동방정식의 형태를 띄나, 실제 해는 그와 무관함으로 복원방식의 한계 때문에 생김. 따라서 Total Variation과 같은 타원형방정식을 사용하면, 이런 영상 왜곡를 누그러 뜨리는 현상이 있음.


우응제 경희대학교 생체의공학과

Contact : Jin Keun Seo

Aug. 2, 2016 - Aug. 2, 2016

이경훈 학위논문 심사위원


Bastian von Harrach University of Stuttgart

Contact : Jin Keun Seo

July 29, 2016 - Aug. 4, 2016

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김태연 Khalifa University of Science

Contact : Eun-Jae Park

July 18, 2016 - Aug. 5, 2016

Prof. Tae Yeon Kim is an assistant professor in the Civil Infrastructure and Environmental Engineering at Khalifa University in UAE. He has expertise in numerical analysis of various engineering fields such as fluid mechanics, biomechanics, solid mechanics, and so on.

During his visit, he will work on two research projects in geophysical fluid dynamics and biomechanics with Prof. Eun-Jae Park.

In geophysical fluid dynamics, Prof. Tae Yeon Kim will work on error analysis of the B-spline based finite-element method for the large-scale ocean circulation with Prof. Eun-Jae Park. He will also develop the two-level finite element discretization for the efficient simulation of the nonlinear ocean circulation models. In biomechanics, Prof. Tae Yeon Kim will provide the mathematical formulation for the numerical analysis of the shape deformation on giant unilamellar vesicles (GUVs). GUVs are simplified close form of cell membrane that can be used for drug delivery. Based on this formulation, he will derive the discontinuous Galerkin formulation and perform mathematical analysis with Prof. Eun-Jae Park. Prof. Tae Yeon Kim will also perform numerical simulation to find the equilibrium shape of vesicles.

From this collaboration, we will publish a couple of papers in high impact journals in the fields of biomechanics, numerical analysis, and fluid dynamics and establish solid research collaboration with Khalifa University in UAE.


FOUXON, YITZHAK Weizmann Institute of Science, Israel

Contact : Changhoon Lee

Feb. 15, 2016 - Feb. 26, 2016

1. 공동연구 수행 : 다음의 주제에 대하여 해당 대학원생의 공동지도 및 공동연구/논문작성 수행

a. Local/delocalization problem: 온도분포가 국부적으로 이차곡선의 분포를 갖고 바깥쪽에는 일정한 분포를 가질 때 부유된 aerosol의 농도가 온도 최소지점에서 높아지는thermophoresis현상과 St수가 커짐에 따라 입자들의 분포가 오히려 낮아지는 현상에 대한 이론적, 수치적 규명 (담당

대학원생: 이정훈)

b. Collision kernel 개발: 강우 생성에 필수적인 액적들간의 충돌 특성을 규명하기 위해서 등방성 난류에서 중력에 의해서 낙하하는 액적들의 거동에 대한 이론적 이해 및 수치적 계산을 통한 이론의 검증을 수행 (담당 대학원생: 이슬기)

c. Convection/stratified조건에서 구 주위의 항력: 배경유동의 성층화/대류 조건에서 미세한 구 주위의 유동을 이론적/수치적으로 조사하고 Stokes 항력의 수정부분을 예측하고 수치적으로 검증 수행 (담당 대학원생: 이호준)

 

2. 집중강연: 

Nonequilibrium statistical physics주제로 2주간의 집중강연을 통해 입자 부유된 난류의 통계역학적 접근 방법에 대한 학생들의 이해도를 높임

기간: 2015.02.16.-25 (8일간 진행)

장소: ASTC 516

​강연제목: Intensive course on nonequilibrium statistical physics

내용: The main aim of this course is that listeners obtain clear concrete understanding of the use of stochastic equations. We consider Brownian motion as prototype problem of non-equilibrium physics using separation of time scales to derive effective equation on particle's velocity as a consequence of ergodicity The concept of ergodicity will be explained demanding no prior knowledge. The students learn on this case the concepts of universal applicability: the fluctuation-dissipation theorem, Kubo formulas, thermodynamic theory of fluctuations, Langevin and Fokker-Planck equations, Kramers problem, equilibrium and non-equilibrium steady states. Then the course transfers the notions learnt in Brownian motion to the general case considering fluctuations of macroscopic variables as variables with time-scale much larger than the microscopic time-scales.Depending on time left the course ends with the study of the Boltzmann equation and molecular chaos assumption, H-theorem and evolution of initial states to local thermal equilibrium, Knudsen number, fluid mechanics as universal description of gas evolution over macroscopic time-scales.


Yizhuang Song Shandong Normal University

Contact : Jin Keun Seo

Feb. 11, 2016 - Feb. 24, 2016

요약: This joint work aims to provide a method of using magnetic resonance electrical impedance tomography (MREIT) to visualize local conductivity changes associated with evoked neuronal activities in the brain. MREIT is an MRI-based technique for conductivity mapping by probing the magnetic flux density induced by an externally injected current through surface electrodes. Since local conductivity changes subject to evoked neural activities are very small (less than a few \%), a major challenge is to acquire exogenous magnetic flux density data exceeding a certain noise level. Noting that the signal-to-noise ratio is proportional to the square root of the number of averages, it is important to reduce the data acquisition time to get more averages within a given total data collection time. Our method uses a sub-sampled k-space data set in the phase-encoding direction to significantly reduce the data acquisition time. Since the sub-sampled data violates the Nyquist criteria, we only get a nonlinearly wrapped version of the exogenous magnetic flux density data, that is insufficient for conductivity imaging. Taking advantage of the sparseness of the conductivity change, the proposed method detects local conductivity changes by estimating the time-change of the Laplacian of the nonlinearly wrapped data.

 

공동연구

During staying in CSE department, I discussed functional MREIT with Prof. Jin Keun Seo in CSE department of Yonsei University and Prof. Habib Ammari from Swiss Federal Institute of Technology Zurich. We complete the mathematical part of our collaboration work “Functional magnetic resonance electrical impedance tomography”. After modifying some minor mistakes and complete the abstract, introduction and discussion and conclusion part we will submit this paper.

 

대학원생 취업률 증진을 위한 세미나 개최: 의료영상처리 알고리즘 개발

참석자: 장재성, 이경훈, 김부권, 이성민, 이승리, 김화평, 권혁남, 박형석


Yizhuang Song Shandong Normal University

Contact : Jin Keun Seo

Feb. 11, 2016 - Feb. 11, 2016

요약: This joint work aims to provide a method of using magnetic resonance electrical impedance tomography (MREIT) to visualize local conductivity changes associated with evoked neuronal activities in the brain. MREIT is an MRI-based technique for conductivity mapping by probing the  magnetic flux density induced by an externally injected current through surface electrodes. Since local conductivity changes subject to evoked neural activities are very small (less than a few \%), a major challenge is to acquire exogenous magnetic flux density data exceeding a certain noise level. Noting that the signal-to-noise ratio is proportional to the square root of the number of averages, it is important to reduce the data acquisition time to get more averages within a given total data collection time. Our method uses a sub-sampled k-space data set in the phase-encoding direction to significantly reduce the data acquisition time. Since the sub-sampled data violates the Nyquist criteria, we only get a nonlinearly wrapped version of the exogenous magnetic flux density data, that is insufficient for conductivity imaging. Taking advantage of the sparseness of the conductivity change, the proposed method detects local conductivity changes by estimating the time-change of the Laplacian of the nonlinearly wrapped data.

공동연구
During staying in CSE department, I discussed functional MREIT with Prof. Jin Keun Seo in CSE department of Yonsei University and Prof. Habib Ammari from Swiss Federal Institute of Technology Zurich. We complete the mathematical part of our collaboration work “Functional magnetic resonance electrical impedance tomography”. After modifying some minor mistakes and complete the abstract, introduction and discussion and conclusion part we will submit this paper.  

대학원생 취업률 증진을 위한 세미나 개최: 의료영상처리 알고리즘 개발
참석자: 장재성, 이경훈, 김부권, 이성민, 이승리, 김화평, 권혁남, 박형석


박수형 Konkuk University

Contact : Jung-il Choi

Jan. 28, 2016 - Jan. 28, 2016

난류천이 방정식을 이용한 경계층 천이유동 해석


장익수 대구경북과학기술원

Contact : Jin Keun Seo

Dec. 17, 2015 - Dec. 17, 2015

장익수: Big-data analysis of cortical thickness of human brain measured by MRI  to uncover and predict dementia progression 

정용은: CLINICAL APPLICATION OF FAT MEASUREMENT


백종덕 Yonsei University

Contact : Jin Keun Seo

Nov. 13, 2015 - Nov. 13, 2015

의료기기 산업은 IT, 기계, 재료, 바이오, 화학, 의학 등 다학제적 지식이 요구되는 대표적인 융합기술로 분류가 됩니다. 최근 고령사회 도래 및 웰빙 확산 등으로 의료기기 시장은 확대 추세이며, 우리 나라 역시 고령화 사회 도래로 인해 예전 질병 치료 위주의 Health care에서 예방 및 건강관리 중심의 health care로 관심이 변화해 가고 있습니다. 세계 의료기기 산업은 의료진단 기기의 대표적인 기업인 GE, Siemens, Philips등이 주류를 이루고 있으나, 최근에는 삼성 역시 Health care 산업의 중요성을 인식하고 미래 신성장 동력 사업으로 과감한 투자를 진행하고 있습니다. 본 세미나에서는 다양한 의료 영상 진단 장비 중 컴퓨터 단층 촬영 진단 기기(Computed Tomography)에 대해 설명하고 기존 시스템의 한계를 극복할 수 있는 새로운 개념의 CT system (Inverse geometry CT system) 및 이와 관련된 영상 복원 및 보정 방법들에 대해 소개하겠습니다.