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돼지 간의 허혈/재관류시 혈역학 및 Nitric Oxide 의 변화
임동건,김준우,송경은,황윤진,한창규,정석현 대한마취과학회 2000 Korean Journal of Anesthesiology Vol.38 No.2
Background : Surgical hepatic inflow obstructions such as the Pringle Maneuver (PM) or hepatic vascular exclusion (HVE) can reduce bleeding during hepatic resection, but ischemia/reperfusion injury of the liver and systemic hemodynamic changes are also inevitable during and after PM or HVE. Nitric oxide plays a pivotal role in ischemia/reperfusion injury. We evaluated hemodynamic changes and changes of nitric oxide during liver ischemia/reperfusion injury excluding the effects of intestinal ischemia. Methods : Liver ischemia was induced by clamping of the portal triad, infrahepatic and suprahepatic inferior vena cava for 90 minutes. To exclude the effects of intestinal ischemia during liver ischemia, portal and iliac venous blood was bypassed to the jugular vein using a pump. Hemodynamic parameters and nitric oxide were measured serially; before and during ischemia, and after reperfusion. Results : Mean arterial blood pressure (MAP) was well-maintained during ischemia, but after reperfusion, MAP, cardiac output (CO) and stroke volume (SV) sipnificantly decreased (35―40, 30―40 and 30%, respectively) postischemra. Compared to preischemia, systemic vascular resistance and heart rate did not change after reperfusion. Pulmonary vascular resistance and mean pulmonary arterial blood pressure significantly increased (220―250% and 60―70%) after reperfusion. Nitric oxide (NO) did not change until 20 minutes after reperfusion, bot after 40 minutes reperfusion, NO significantly decreased (20%) compared to preischemia. Conclusions : After 90 minutes warm liver ischemia/reperfusion causes hypotension induced by decreased CO and SV. Increased PVR seems to be the cause of decreased CO and SV. NO-SVR interaction does not seem to be the cause of postreperfusion hypotension. (Korean J Anesthesiol 2000; 38: 333~339)
임동건,곽동주,G. S. Kang,박민우,S. I. Kwon 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.6
In this paper, we report an investigation into the feasibility of aluminum-doped zinc-oxide (ZnO:Al) films as transparent conducting oxide layers for plasma panel displays. ZnO:Al films were deposited on glass substrates by DC magnetron sputtering from a zinc-oxide (ZnO) target mixed with 2 wt.\% Al$_2$O$_3$. The effects of substrate bias on the electrical properties and the film structure were studied. Films deposited with a positive bias had a strong (002) preferred orientation. The electrical resistivity of the film decreased significantly as the positive bias increased. However, as the positive bias increased over +30 V, the resistivity increased. An electrical resistivity as low as 4.3 $\times$ 10$^{-4}$ $\Omega$-cm and an optical transmittance of 91.46 \% were obtained for an 800 nm-thick film deposited at a substrate bias of +30 V.
Numerical methods for crack localization in an anisotropic material using acoustic emission
임동건,권혁남 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5
We developed numerical method to localize crack in an anisotropic medium. Cracks in a domain Ω cause acoustic waves (as shown in Fig. 1) which reach to the boundary of Ω. The waves are measured at a finite number of points on ∂Ω (as shown in Fig. 1). Using the measured waves on ∂Ω, the goal is to find position of cracks in Ω. Under the assumption of homogeneous medium, we consider a velocity of wave propagation is constant. With the constant velocity, we can find the position of crack by minimizing the cost function <수식 본문 참조> where φ<sub>i,j</sub> is discrepancy of velocity at i- and j-th measurement, (x, y) is position of sensort and t is time when crack occurs. The following is definition of φ<sub>i,j</sub> φ<sub>i,j</sub>(x,y,t)=((t-t<sub>j</sub>)<sup>2</sup>((x-x<sub>i</sub>)<sup>2</sup>+(y-y<sub>i</sub>)<sup>2</sup>)-(t-t<sub>i</sub>)<sup>2</sup>((x-x<sub>j</sub>)<sup>2</sup>+(y-y<sub>j</sub>)<sup>2</sup>))<sup>2</sup> We compared the proposed method with the conventional time reverse modeling (TRM) method. In TRM, the measured signals are re-emitted numerically into a domain in a time-reversed manner by solving the linear anisotropic elastic wave equation for the displacement field u<sub>i</sub>(x,t)∈R<sup>d</sup> (d=2 in this paper) which reads: p<sub>g</sub>∂<sub>tt</sub>u<sub>i</sub>=∂<sub>j</sub>(c<sub>ijkl</sub>∂<sub>l</sub>u<sub>k</sub>)+f<sub>i</sub> in Ω × [0,T] where f<sub>i</sub> represents wave force caused by crack, gravitational density is given by p<sub>g</sub> and c<sub>ijkl</sub> denotes the stiffness tensor, which gives the momentum tensor by m<sub>ij</sub> = c<sub>ijkl</sub>∂<sub>l</sub>u<sub>k</sub>. To compare and verify performance in various situations, we perform several numerical experiments. Most of cases both methods are capable of localizing AE activity in concrete. However when the measurements are only on one side, TRM fails to localize crack position while suggested method is still able to localizing crack position (Fig. 2).
간 유입혈류 차단 후 간절제술 시 Isoflurane 과 Propofol 이 술 후 간기능에 미치는 영향 비교
임동건,백운이,박진웅,홍정길,서중교,정석현 대한마취과학회 2000 Korean Journal of Anesthesiology Vol.38 No.3
Background : Anesthesia and surgery may exacerbate liver function in patients with pre-existing liver disease so it is important to choose less hepatotoxic anesthetics in patients with chronic liver disease. Methods : This study was designed to examine the postoperative liver function test in 150 patients after hepatectomy with portal triad clamping through retrospective chart review. Patients were divided into an isoflurane group (group I, n= 56) and a propofol group (group P, n = 57) by used anesthetics for maintaining anesthesia. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase, alkaiine phosphatase, total bilirubin, albumin, and prothrombin time were checked at preoperation, and postoperatively at 1, 3, 7 and 14 days in the two groups. Indocyanine retention rate (ICG-R15) was measured at preoperation, and postoperatively at 1 and 7 days. Results : AST values increased postoperatively at 1, 3, 7, and 14 days compared with preoperation. ALT values increased postoperatively at 1, 3 and 7 days compared with preoperation and there was difference between group I (443.8 ± 52,1 U/L) and group P (202.7 ± 24.7 U/L) at postoperative 1 day. Other values had no significant difference between the two groups. Conclusions : Though it might need a well controlled study to find the differences in effect between isoflurane and propofol on the postoperative liver function test, we concluded that total intravenous anesthesia using propofol is also one of the safest anesthetic methods for hepatic resection with minimal hepatotoxicity. (Korean J Anesthesiot 2000; 38: 463-468)