Intraoperative colonoscopy can find complications of anastomosis early in colorectal surgery

SukHyun Shin,HyungJin Kim,Hyeon-Min Cho,Ri Na Yoo,SeungRim Han 대한종양외과학회 2019 대한임상종양학회 학술대회지 Vol.2019 No.2

Combinatorial effects of fluid shear stress and electric field on dermal fibroblast migration

Sukhyun Song,Hana Han,Jaemin Kim,Unghyun Ko,Jennifer H. Shin 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.4

EFFECTS OF UNIFORM SHEAR STRESS ON THE DYNAMIC RESPONSES OF VASCULAR ENDOTHELIAL CELLS

Sukhyun Song,Jennifer H. Shin 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Hemodynamic forces are essential to maintain the innate characters of vascular endothelial cell (VEC) expressed in its morphological and physiological behavior. The objective of this study is to investigate the effects of uniform shear stress on the dynamic responses of VECs in vitro. By perfusing the growth media through a parallel plate flow chamber which is developed in three-dimensional computational fluid dynamics analysis, we can observe the dynamic behavior of cells in real time for a long term period. Under various flow conditions, the shear stress effects on the cell motility and proliferation rate in the mouse micro-vessel endothelial cell are studied. Surprisingly, we observe that most cells show the tendency to migrate against the flow direction independently of the magnitude of shear stress. Moreover, we examine that proliferation rate is decreased as the shear stress magnitude increases. The dynamic responses of VECs such as cell migration and proliferation rate exhibit significant changes depending on the magnitude of shear stress.

세포기질의 강성이 전단응력으로 유도된 혈관내피세포 운동성에 미치는 영향에 대한 연구

송석현(Sukhyun Song),김미나(Mina Kim),김현유(Hyeonyu Kim),신현정(Jennifer H. Shin) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

Vascular endothelial cell (VEC) forms a monolayer on the smooth muscle cell layer of blood vessel. Thus, substrate stiffness should be considered as one of the most important element in mimicking the physiological condition of VECs. In this research, the effect of substrate stiffness on shear stress induced cellular motility was investigated. VECs are seeded on polydimethylsiloxane (PDMS) substrate with controlled stiffness, ranging from 1.78 ㎫ to 48 ㎪. Shear stress system based on parallel plate flow chamber is utilized to apply laminar shear stress of 15 dyne/㎠. In order to explain the detailed mechanism of cellular migration, expression and distribution of cytoskeleton related pathway consisting RhoA, Rac1 and Cdc42 are examined. In addition, the regulation of syndecan-4 is observed as a mechanoreceptor. Results reveal that there is an optimal stiffness in maximizing the cell motility.

상처치유의 상승작용을 유도하는 유동전단응력과 전기장의 복합자극

송석현(Sukhyun Song),김재민(Jaemin Kim),한하나(Hana Han),신현정(Hyunjong Shin) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

In injured tissues, interstitial flow and endogenous electric field are naturally generated to enhance healing process. These physical stimulations are known to play a vital role in wound healing process such as migration and ECM (extracellular matrix) production. To examine the combinatorial effects of fluid shear stress and electric field on the migration of fibroblast, an integrated microfluidic platform with an agar salt bridge was developed using soft lithography. Our preliminary results showed that two directional cues, mimicking the wounded situation, induce directional migration of fibroblasts to yield positive effects on healing of the wounds. Further researches are in progress to understand the synergetic effects of shear stress and electric fields in regard to the translocation of membrane receptors and ECM protein synthesis.

Collaborative effects of electric field and fluid shear stress on fibroblast migration.

Song, Sukhyun,Han, Hana,Ko, Ung Hyun,Kim, Jaemin,Shin, Jennifer H Royal Society of Chemistry 2013 Lab on a chip Vol.13 No.8

<P>Cells are inherently exposed to a number of different biophysical stimuli such as electric fields, shear stress, and tensile or compressive stress from the extracellular environment in vivo. Each of these biophysical cues can work simultaneously or independently to regulate cellular functions and tissue integrity in both physiological and pathological conditions. Thus, it is vital to understand the interaction of multiple stimuli on cells by decoupling and coupling the stimuli in simple combinations and by investigating cellular behaviors in response to these cues. Here, we report a novel microfluidic platform to apply the combinatorial stimulation of an electric field and fluid shear stress by controlling two directional cues independently. An integrated microfluidic platform was developed using soft lithography to monitor the cellular migration in real-time in response to an electric field and fluid shear stress in single, simultaneous, and sequential modes. When each of these stimulations is applied separately, normal human dermal fibroblasts migrate toward the anode and in the direction of fluid flow in a dose-dependent manner. Simultaneous stimulation with an electric field and shear stress, which mimics a wound in vivo, enhances the directional migration of fibroblasts by increasing both directedness and trajectory speed, suggesting the plausible scenario of cooperation between two physical cues to promote wound healing. When an electric field and shear stress are applied sequentially, migration behavior is affected by the applied stimulation as well as pre-existing stimulating conditions. This microfluidic platform can be utilized to understand other microenvironments such as embryogenesis, angiogenesis and tumor metastasis.</P>

GPU-based interactive visualization framework for ultrasound datasets

Lim, Sukhyun,Kwon, Koojoo,Shin, Byeong-Seok John Wiley Sons, Ltd. 2009 COMPUTER ANIMATION AND VIRTUAL WORLDS Vol.20 No.1

<P>Ultrasound imaging is widely used in medical areas. By transmitting ultrasound signals into the human body, their echoed signals can be rendered to represent the shape of internal organs. Although its image quality is inferior to that of CT or MR, ultrasound is widely used for its speed and reasonable cost. Volume rendering techniques provide methods for rendering the 3D volume dataset intuitively. We present a visualization framework for ultrasound datasets that uses programmable graphics hardware. For this, we convert ultrasound coordinates into Cartesian form. In ultrasound datasets, however, since physical storage and representation space is different, we apply different sampling intervals adaptively for each ray. In addition, we exploit multiple filtered datasets in order to reduce noise. By our method, we can determine the adequate filter size without considering the filter size. As a result, our approach enables interactive volume rendering for ultrasound datasets, using a consumer-level PC. Copyright © 2009 John Wiley & Sons, Ltd.</P>

볼륨프로 하드웨어를 이용한 효율적인 투시투영 방법

임석현(Sukhyun Lim),신병석(Byeong-Seok Shin) 한국정보과학회 2004 정보과학회논문지 : 시스템 및 이론 Vol.31 No.3·4

볼륨프로는 일반 PC상에서도 실시간 볼륨렌더링이 가능하도록 고안된 하드웨어이다. 그러나 볼륨프로는 직교투영(orthographic projection) 기능만 제공하기 때문에 가상 내시경과 같이 투시투영(perspective projection)이 필요한 분야에는 이용할 수 없다. 이런 문제를 해결하기 위해 볼륨 데이타를 여러 개의 슬랩(slab)으로 분할하여 투시투영을 근사하는 방법이 소개되었으나 이 방법은 시각 절두체에 포함되지 않은 부분까지 렌더링 하기 때문에 처리시간이 길어지는 문제가 있다. 본 논문에서는 볼륨프로의 크로핑(cropping) 기능을 이용하여 볼륨 데이타를 여러 개의 서브볼륨으로 분할함으로써 효율적인 투시투영이 가능하도록 하는 방법을 제안한다. 이 방법은 시각 절두체(view frustum)에 포함되는 부분만 렌더링하므로 슬랩을 이용하는 기존 방법과 동일한 화질을 가지면서 처리시간을 단축시킨다. VolumePro is a real-time volume rendering hardware for consumer PCs. However it cannot be used for the applications requiring perspective projection such as virtual endoscopy since it provides only orthographic projection. Several methods have been presented to approximate perspective projection by decomposing a volume into slabs and applying successive parallel projection to them. But it takes a lot of time since the entire region of every slab should be processed, which does not contribute to final image. In this paper, we propose an efficient perspective projection method that makes the use of several sub-volumes with cropping feature of VolumePro. It reduces the rendering time in comparison to slab-based method without image quality deterioration since it processes only the parts contained in the view frustum.

A Data Structure for Real-time Volume Ray Casting

임석현(Sukhyun Lim),신병석(Byeong-Seok Shin) 한국컴퓨터그래픽스학회 2005 컴퓨터그래픽스학회논문지 Vol.11 No.1

메타버스(metaverse)를 통한 비대면 강좌 개발 및 운영 사례 연구 : 충청남도 S대학교 사례를 중심으로

김석현(Sukhyun Kim),신금수(Geumsu Shin),이종찬(Jongchan Lee) 한국비교과교육학회 2021 비교과교육연구 Vol.2 No.2

본 연구는 충청남도 S대학교의 메타버스를 통한 비대면 강좌 개발․운영 사례를 통해 S대학교의 학생맞춤형 메타버스 플랫폼의 질적 제고와 교육시스템으로의 발전 방향을 모색하는데 목적이 있다. 이러한 목적을 달성하기 위해, S대학교는 기존의 대면 교양강의 중 가장 수강생이 많았지만 COVID-19으로 인해 비대면 수업으로 전환되면서 교수자와 학습자와의 소통부재 문제가 부각된 ‘피닉스 열린 강좌’를 메타버스로 구현하여 2021학년도 2학기에 시범 운영하였다. 운영 결과, 수업 참여자들의 아바타 “과잠(학과 점퍼)”를 통한 소속감 고취, 메타버스로 구현된 대강당에서 본인의 아바타를 활용하여 소통함으로써 몰입감 상승, SNS를 통한 상호작용으로 인해 교수자와의 친밀감이 향상된 것으로 나타났다. 또한 COVID-19에 따른 사회적 거리두기의 제한이 없는 가상공간을 제공할 수 있다는 이점도 있었다. 그러나 제한된 디바이스로만 접속이 가능했고, 모바일 기반의 플랫폼으로서의 제약이 있었기에 국내 최초로 메타버스를 활용한 정규 강좌라는 점에도 불구하고 아직까지는 실험적 단계에 놓여 있다. 비대면 환경에서의 온라인 수업이 갖는 몰입감의 부재와 교수자와 학습자와의 커뮤니케이션이 어렵다는 점을 메타버스를 통해 일정부분 해소할 수 있었다는 면에 있어서 그 시사점을 찾을 수 있다. The purpose of this study is to strengthen the competitiveness and quality of S University internally by presenting cases of non-face-to-face course development and operation through a metaverse at S University in Chungcheongnam-do, and to provide implications for non-face-to-face courses through various metaverses to be external. To achieve this goal, Chungcheongnam-do S University selected Phoenix Open Course, which had the largest number of students among existing face-to-face liberal arts lectures, but highlighted the lack of communication between instructors and learners, and operated the metaverse non-face-to-face courses in the second semester of 2021. As a result of the operation, it was found that the research participants’ sense of belonging through their avatar “Department Uniform (department jumper),” immersion in participating in the large auditorium implemented as the metaverse, and intimacy with instructors through communication using SNS functions were improved. In addition, there was an advantage that it could provide a space without restrictions on social distancing under COVID-19. However, it has not yet overcome the limitations of access to limited devices and mobile-based platforms, and there are also limitations that are still in the experimental stage in that it is the first lecture in Korea using a metaverse. In the prolonged COVID-19 pandemic situation, the lack of immersion in existing non-face-to-face lectures and difficulty in communicating with instructors and learners were able to be resolved slightly through non-face-to-face lectures through a metaverse.