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심근정지후 심근세포의 회복과정과 심근정지용액에 관한 연구
서창국,박소라,박혜수,이영호,강복순,Suh, Chang-Kook,Park, So-Ra,Park, Hye-Soo,Lee, Young-Ho,Kang, Bok-Soon 대한생리학회 1988 대한생리학회지 Vol.22 No.1
The changes in membrane potential and intracellular $Ca^{2+}$ activities along with adenosine triphosphate (ATP) and creatine phosphate (CP) contents of guinea pig hearts were studied during the cardioplegia and recovery phase. The results obtained were summarized as follows: 1) A low concentration of $Ca^{2+}$ in the cardioplegic solution caused significant changes in membrane potential during the cardioplegia and action potential configurations of the first beat after cardioplegia. 2) Intracellular $Ca^{2+}$ activities were decreased significantly during cardioplegia and increased when the cardiac tissue was reperfused with the normal Tyrode solution. The magnitude of increase in intracellular $Ca^{2+}$ activities was larger in the 0.1 mM $Ca^{2+}-cardioplegic$ solution than the 1.8 mM $Ca^{2+}-solution$. 3) ATP and CP contents of cardiac ventricular tissue were decreased during the cardioplegia, regardless of $Ca^{2+}$ concentration in the cardioplegic solutions, and CP contents were recovered with the reperfusion of normal Tyrode solution faster than those of ATP. And, there were no significant differences in the recovery of CP contents with different concentrations of $Ca^{2+}$ in the cardioplegic solutions tested, while the recovery of ATP contents was faster with $15mM\;K^{+},\;0.1mM\;Ca^{2+}$ cardioplegic solution. These results suggest that the $Ca^{2+}$ concentration in the cardioplegic solution is one of major factors influencing the recovery of cardiac tissue from the cardioplegia.
강건 제어를 통한 곤돌라 탑재형 외벽청소로봇의 수직 외란 제거 및 장애물 주변의 청소 성능 향상
서창국(Changkook Seo),김경민(Kyungmin Kim),김한봄(Hnabom Kim),김화수(Hwasoo Kim),서태원(TaeWon Seo) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
The number of high-rise buildings continues to increase in modern times, and as a result, various façade cleaning robots are being developed, and efforts are also being made to protect workers from dangerous work through automated façade cleaning robots. In order to clean the entire wall of such robots, it is essential to overcome obstacles such as outer wall structures and clean them. Robots currently developed are overcoming obstacles through instrumental or simple control. However, in most cases, it can be seen that uncleaned areas are not fully cleaned or disturbances arising from gondola operations cannot be eliminated, resulting from the disturbance on the gondola. In this paper, z-axis manipulation and H-infinite control based control allow us to overcome obstacles entirely while eliminating disturbances and minimizing uncleaned areas.
Robust design of a screw-based crawling robot on a granular surface
ChangKook Seo(서창국),KyungUK Lee,DongHan Son,TaeWon Seo 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
In this paper, a robust design of a screw wheel is presented, based on the Taguchi method to accelerate a screw-based crawling robot. Screw-based crawling robots have been studied before, but their application is limited because of their limited speed. To solve this problem, robust design is applied for the screw wheel geometry driving on granular surfaces, such as desert sand. Each of the four parameters determining the screw wheel geometry and two user conditions were set at three levels, and the Taguchi method was applied through the L_9 (3^4) orthogonal array. The experimentally optimized parameters were as follows: the slope angle was 35°, the height of the blade was 14 mm, the number of spirals was one, and the blade had a semicircular cross-section. In conclusion, the robust design using the Taguchi method is suitable for solving the speed problem of a screw-based crawling robot on a granular surface.
흡입마취제인 Sevoflurane 의 심근수축 억제기전에 대한 기계적 및 전기생리학적인 연구:Isoflurane 과의 비교
박윤곤,서창국 대한마취과학회 1995 Korean Journal of Anesthesiology Vol.28 No.3
Dose-related depression of left ventricular function or cardiac output has been reported in humans and in vivo animal studies with sevoflurane (SEVO) anesthesia and myocardial depressant effect of SEVO appeared to be comparable to that produced by isoflurane (ISO). This study was designed to determine the mechanical and electrophysiologic mechanism of the direct negative inotropic effects of SEVO. The effects of SEVO were comprared to those produced by equipotent concentration of ISO in the same isolated myocardial preparations. Isometric force of isolated guinea pig ventricular papillary muscle was studied in normal and 26 mM K^+Tyrode's solution. Rat papillary muscle was also used to evaluate the effect on Ca^(2+) release from the sarcoplasmic reticulum (SR) at low stimulation rates. Muscles were bathed at 36-37℃ in normal K Tyrode's solution bubbled with 95% O₂/ 5% CO₂ (pH 7.4) and were electrically stimulated following rest and at rates up to 3 Hz. Normal and slow action potentials were evaluated by using cnventional microelectrodes. Muscles were also subjected to rapid cooling (from 37℃ to 2℃) in order to elicit a transient rapid cooling contracture (RCC) known to be activatel by Ca^(2+) content released from the SR. RCCs were elicited after 2 Hz stimulation, which produced an RCC tension similar to that of the preceding contraction in control. SEVO and ISO were administered by dial setting in each vaporizer at 1.7 (1 MAC) and 3.4% (2 MAC), and 1.15 (1 MAC) and 2.3% (2 MAC), respectively. ∼20% and 40% depression of contractility was shown at 1.7 and 3.4% concentration of SEVO and the extent of depression was similar to equipotent concentration of ISO from rested state up to 3Hz stimulation rates. 1 and 2 MAC concentrations of SEVO (1.7 and 3.4%) or ISO (1.15% and 2.3%) in normal K^+ Tyrode's solution caused dose-related depression of peak force at low stimulation rates (RS, 0.1, and 0.5 Hz). Although the normal action potential (AP) amplitude or Vmax were not changed, APD_(50) and APD_(90) were prolonged characteristicly at 2 MAC of both anesthetics. Whereas no contractile depression was shown at RS and 0.1 Hz stimulation rates in rat papillary muscles, significant depression was noted from 0.5 to 3 Hz in 3.4% SEVO or 2.3% ISO. In the partially depolarized (26 mM K^+Tyrode's solution) β-adrenergically stimulated myocardium, 2 MAC concentration of both anesthetics caused selective depression of late peak in the biphasic contraction without changing early peak. In slow AP, 3.4% SEVO or 2.3% ISO did not cause any change in AP amplitude and Vmax whereas APD_(50) and APD_(90) were prolonged as in Normal APs. Rapid cooling preceded by 15 min rest showed little contractile force and marked prolongation of the time to peak contracture with almost complete absence of contracture after 2Hz stimulation rates following 3.4% SEVO or 2.3% ISO. Although complete recovery of peak force could be observed, little restoration of RCC was shown after washout for 15 minutes at 2 MAC concentration of both anesthetics characteristically. The effect ofSEVO on isolated myocardial contraction was similar to that of ISO. While neither anesthetic depressed the rapid initial Ca+ release from the SR, the depression of RCC and late tension suggest an alteration in some SR pathway. The direct myocardial depressant effects of SEVO and ISO are likely to be related to depressed Ca^(2+) influx through the cardiac memebrane, while AP prolongation may be due to actions on K^+currents.
Mepivacaine의 심근수축 억제기전에 대한 기계적 및 전기생리학적인 연구
박윤곤,이행철,서창국 대한마취과학회 1997 Korean Journal of Anesthesiology Vol.32 No.4
Background: The effects of various concentration (20, 50, 100? M) of mepivacaine were studied in isolated guinea pig and rat right ventricular papillary muscles by measuring the effects on myocardial contractility and electrophysiological parameters. Methods: Isometric force of isolated guinea pig ventricular papillary muscle was studied in modified normal and 26 mM K+ Tyrode's solution. Rat papillary muscle was used to evaluate the effect on Ca2+ release from the sarcoplasmic reticulum (SR) at low stimulation rates. Normal and slow action potentials (APs) were evaluated by using conventional microelectrode technique. Rapid cooling contractures (RCCs), an index of SR Ca2+ content, which are known to be activated by Ca2+ released from the SR were performed. Results: Mepivacaine caused dose-dependent depression of peak force from 0.5 to 3 Hz stimulation rates in guinea pig papillary muscles. Conduction block was frequently noted especially at higher stimulation rates (2 and 3 Hz) at all concentration ranges. In rat, ∼20% depression of peak force was shown at rested state contraction. Shortening of AP duration and rate-dependent depression of dV/dt max could be observed at 100 M mepivacaine. In 26 mM K+ Tyrode's solution, 50 and 100 M mepivacaine caused dose-dependent depression of early and late force development. In slow APs, neither shortening of AP duration nor changes of dV/dtmax were not shown at 100 M mepivacaine. ∼30% depression of RCC after 2 Hz stimulation rate was shown at 100 M mepivacaine. Conclusion: It may be concluded that the direct myocardial depressant effects of mepivacaine may partly be related to inhibition of Ca2+ release from the SR. Shortening of AP duration in normal APs seems to be partly related by blockade of TTX-sensitive $quot;window$quot; Na+ current. (Korean J Anesthesiol 1997; 32: 491∼503)