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In vivo measurement of blood flow in micro-circulation systems and their structural rules
이정엽(Jung Yeop Lee),이상준(Sang Joon Lee) 한국가시화정보학회 2008 한국가시화정보학회 학술발표대회 논문집 Vol.- No.2
The micro circulation system which is distributed in the entire body plays an important role in maintaining the metabolism and transport nutrients and wastes. In addition, the hemodynamic characteristics of blood flow such as wall shear stress and flow rate are important factors that affect angiogenetic process and control the vasomotion and dilatation of the vessel adaptively. These factors of blood flow in the micro circulation system are crucial in the development of the cardiovascular system as well as for the proper functioning of an organism, especially when the blood flow is related to circulatory diseases. Moreover, the structural characteristics of blood vessels (Murray’s law and bifurcation pattern) are significantly influenced by blood flow. Therefore, it is important to measure the blood flow in vivo and determine its relation to the structural rules of the vessel. In this study, we measured the blood flow in the extraembryonic arterial blood vessels of chicken embryos and correlated the hemodynamic characteristics and the structural rules of the vessels along the bifurcation cascade. Blood flow was measured using a micro-PIV technique and the temporal characteristics of the flow were obtained using a high-speed CMOS camera. The mean velocity in the arterial blood vessels was observed to decrease and Womersley number (α) calculated based on the pulsating frequency and diameter of the vessel also decreased as the bifurcation cascaded. The ratio of Murray’s law (= D?³/(D₁³ + D₂³), where D?, D₁, and D₂ are the diameters of the parent and two daughter vessels, respectively) was very close to the theoretical value of 1 when the vessel diameter was small (50 ㎛ ≤ D? ≤ 100 ㎛). However, the value deviated from 1 as D? increased. The bifurcation angles were wider when the D? was smaller and became narrower as D? increased. These results indicate that Poiseuille’s formula is best approximated for smaller vessels (when Womersley number approaches to zero).
인지서사학 관점에서 본 게임학 연구 -< 스탠리 패러블 >을 중심으로-
이정엽 ( Jung Yeop Lee ) 한민족어문학회 2015 韓民族語文學 Vol.0 No.71
이 논문은 최근 조금씩 대안적인 서사 분석 방법론으로 인지도를 모아가고 있는 인지서사학의 방법론을 바탕으로 비디오 게임의 서사를 분석하는 것을 목표로 삼는다. 인지서사학의 주요 개념을 바탕으로 기존에 논의되었던 게임학의 용어와 개념들을 상호 비교하고 일치시켜 보면서 서사학과 게임학이 대립해왔던 논쟁의 절충 지점을 찾고자했다. < 스탠리 패러블 >의 작품 분석을 통해 이와 같은 인지서사학적 관점을 적용해 보았다. This paper aims to analyze the narrative of video games with cognitive narratology, which has gradually gathered some awareness as alternative methodology of the various narrative. I had tried to find a compromise with famous dispute between narratologists versus ludologists as comparing the terms and concepts of cognitive narratology and ludology each other. I applied these cognitive narratological method to an indie game, The Stanley Parable.
유정란의 다양한 혈관 내부 혈액유동의 in-vivo 계측
이정엽(Jung-Yeop Lee),지호성(Ho-Seong Ji),이상준(Sang-Joon Lee) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
Analyzing blood flow characteristics in blood vessels is very important to diagnose the circulatory diseases. In order to verify the hemodynamic characteristics, in-vivo measurements of blood flow inside extraembryonic blood vessels of a chicken embryo were carried out using a micro-PIV technique. We obtained velocity information in various bifurcated blood vessels. The flow images of RBCs in the whole blood vessels were obtained using a high-speed CMOS camera. The mean velocity fields obtained show non-Newtonian flow characteristics. The blood in bifurcated vessels merged smoothly without any flow separation into the main blood vessel. In addition, the pulsating frequency of blood flow in an artery was analyzed using FFT analysis of PIV velocity field data.
유정란 태아외부혈관의 단계적으로 분기되는 동맥 분지관 내부 혈액 유동특성의 in vivo 계측
이정엽(Jung Yeop Lee),이상준(Sang Joon Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
The arteries are very important in cardiovascular system and easily adapt to varying flow and pressure conditions by enlarging or shrinking to meet the given hemodynamic demands. The blood flow in arteries is dominated by unsteady flow phenomena due to heart beating. In certain circumstances, however, unusual hemodynamic conditions cause an abnormal biological response and often induce circulatory diseases such as atherosclerosis, thrombosis and inflammation. Therefore quantitative analysis of the unsteady pulsatile flow characteristics in the arterial blood vessels plays important roles in diagnosing these circulatory diseases. In order to verify the hemodynamic characteristics, in vivo measurements of blood flow inside the extraembryonic arterial bifurcation cascade of a chicken embryo were carried out using a micro-PIV technique. To analyze the unsteady pulsatile flow temporally, the flow images of RBCs were obtained using a high-speed CMOS camera at 250fps with a spatial resolution of 14.6㎛×14.6㎛ in the whole blood vessels. The variation of flow and frequency characteristics strongly depends on the blood and vessel parameters. The mean velocity in the arterial blood vessel was decreased and pulsating frequency obtained by FFT analysis of velocity data extracted in front of the each bifurcation was also decreased as the bifurcation cascaded.
이정엽(Lee, Jung Yeop) 한국게임학회 2015 한국게임학회 논문지 Vol.15 No.6
이 논문에서는 비디오 게임의 역사를 보존 연구하기 위한 아카이브들의 국내 사례와 해외 사례를 비교 조사하고, 이를 통해 게임 역사박물관 구축을 위한 기초적인 자료 분류와 구축 방식을 제안하고자 한다. 게임의 역사를 수집, 보존하는 것은 일차적으로는 게임학 연구를 위한 기초자료를 구축하고자 위함이지만, 이러한 운동이 꼭 연구만을 위한 목적으로 귀결되는 것은 아니다. 따라서 본 논문에서는 디지털 게임을 수집, 보존, 분류, 전시, 열람하는 일련의 과정을 미디어 고고학(media archeology)이라는 새로운 학문 분야에 바탕하여 접근하고자 한다. This paper made a comparative study on domestic and international game archives that preserve and study the history of games. Based on that, it suggests the structure to classify and build a database to establish a history museum of games. The objective to gather and preserve history of games is mainly in order to build a baseline for ludology studies, but not solely for that reason. This study proposes the series of procedures of gathering, preserving, classifying, displaying and referencing digital games according to the academic field of Media Archaeology.
이정엽(Jung Yeop Lee),이상준(Sang Joon Lee) 한국가시화정보학회 2009 한국가시화정보학회 학술발표대회 논문집 Vol.2009 No.11
Pulsatile blood flows in omphalo-mesenteric arteries of HH-stage 18 chicken embryos are measured using a time-resolved particle image velocimetry (PIV) technique to obtain hemodynamic information in microcirculations and compare hemodynamic properties of pulsatile blood flows. Due to the intrinsic features of pulsatile flow and complicated vessel network of microcirculation, an out-of-phase motion of blood occurs in nearby vessel segments of bifurcations. This is mainly attributed to the morphological characteristics and peripheral resistance of vasculature. The out-of-phase motion is quantitatively identified using the onedimensional temporal cross-correlation function. This cross-correlation function is extended to establish the phasic relationships among hemodynamic properties such as velocity, shear rate, and acceleration. Velocity and shear rate are almost in phase, as predicted theoretically. On the other hand, velocity (or shear rate) shows an almost 180° out-of-phase against acceleration, which is quite larger than the theoretically predicted value. From the time-resolved PIV data obtained in this study, we can observe the dynamic variations of hemodynamic properties and their relationships. The velocity waveforms at low Womersley number (Ω) regime can be used as input data for the analytical calculation of the governing equations for the pulsatile flow.