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이동하 대한의생명과학회 2021 Biomedical Science Letters Vol.27 No.4
Physiological agents trigger a signaling process called "inside-out signaling" and activated platelets promote adhesion, granule release, and conformational changes of glycoprotein IIb/IIIa (αIIb/β3). Activated αIIb/β3 interacts with fibrinogen and initiates a second signaling step called "external signaling". These two signaling pathways can cause hemostasis or thrombosis, and thrombosis is a possible medical problem in arterial and venous vessels, and platelet-mediated thrombosis is a major cause of cardiovascular disease (CVD). Therefore, modulating platelet activity is important for platelet-mediated thrombosis and cardiovascular disease. Esculetin is a coumarin-based physiologically active 6,7-dihydroxy derivative known to have pharmacological activity against obesity, diabetes, renal failure and CVD. Although some studies have confirmed the effects of esculetin in human platelet activation and experimental mouse models, it is not clear how esculetin has antiplatelet and antithrombotic effects. We confirmed the effect and mechanism of action of escultein on human platelets induced by collagen. As a result, esculetin decreased Ca2+ recruitment through upregulation of inositol 1, 4, 5-triphosphate receptor. In addition, esculetin upregulates cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP)-dependent pathways and inhibits fibrinogen binding and thrombus contraction. Our results demonstrate the antiplatelet effect and antithrombotic effect of esculetin in human platelets. Therefore, we suggest that esculetin could be a potential phytochemical for the prevention of thrombus-mediated CVD.
이동하,이만휘,조현정,박화진,김현홍 고려인삼학회 2013 Journal of Ginseng Research Vol.37 No.2
In this study, we have investigated the effects of total saponin from Korean red ginseng (TSKRG) on thrombin-induced platelet aggregation. TSKRG dose-dependently inhibited thrombin-induced platelet aggregation with IC50 value of about 81.1μg/mL. In addition, TSKRG dose-dependently decreased thrombin-elevated the level of cytosolic-free Ca2+ ([Ca2+]i), one of aggregation-inducing molecules. Of two Ca2+-antagonistic cyclic nucleotides as aggregation-inhibiting molecules, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), TSKRG significantly dose-dependently elevated intracellular level of cAMP, but not cGMP. In addition, TSKRG dose-dependently inhibited thrombin-elevated adenosine triphosphate (ATP) release from platelets. These results suggest that the suppression of [Ca2+]i elevation, and of ATP release by TSKRG are associated with upregulation of cAMP. TSKRG elevated the phosphorylation of vasodilator-stimulated phosphoprotein (VASP)-Ser157, a cAMP-dependent protein kinase (A-kinase) substrate, but not the phosphorylation of VASP-Ser239, a cGMPdependent protein kinase substrate, in thrombin-activated platelets. We demonstrate that TSKRG involves in increase of cAMP level and subsequent elevation of VASP-Ser157 phosphorylation through A-kinase activation to inhibit [Ca2+]i mobilization and ATP release in thrombin-induced platelet aggregation. These results strongly indicate that TSKRG is a beneficial herbal substance elevating cAMP level in thrombin-platelet interaction, which may result in preventing of platelet aggregation-mediated thrombotic diseases.
신형 원자력발전소 감시제어체계의 인간/체계 인터페이스 평가 방법에 관한 연구
이동하,임현교,정병용,Lee, Dong-Ha,Im, Hyeon-Gyo,Jeong, Byeong-Yong 대한인간공학회 1999 大韓人間工學會誌 Vol.18 No.3
The design of nuclear control room is advancing toward totally computer based human system interfaces (HSI). Computer based interfaces offer the opportunity to provide improved support of operator performance, but if not properly deployed, can introduce new challenges. This paper reviews the Westinghouse AP-600 Human Factors Verification and Validation Plan selected for HSI evaluation model of Korea next generation nuclear control rooms. The AP-600 HSI evaluation model addressed 15 evaluation issues considering major activity class of operator and task complexity factors. This paper also describes the test procedures experimenters should follow to evaluate the addressed issues.
이동하 대한인간공학회 2022 大韓人間工學會誌 Vol.41 No.2
Objective: The aim of this study is to investigate whether a reinforcement learning (RL) algorithm is effective to improve the accuracy of the safety culture categorization which the author's previous study tried to solve with a convolutional neural net classifier. Background: The RL algorithm using the optimal Bellman equation is nowadays popularly applied to many markov decision process situations. Method: An asynchronous advantage actor critic (A3C) neural net was applied to learn the safety culture survey data collected from a nuclear power industry for safety culture level categorization. Results: The RL algorithm applied to the randomly selected validation data resulted in 97.63% accuracy compared to 96.2% which showed in the previous study. Conclusion: The safety culture level categorization using the A3C neural net is more stable and accurate than the previous convolution neural net classifier. Application: The safety culture level classifier with the RL neural net learning massive survey data might be useful in place of expert interviewers for safety culture evaluation.
이동하,이용희 대한인간공학회 2007 대한인간공학회 학술대회논문집 Vol.- No.-
Gori-I nuclear power plant has been examining the effectiveness and efficiency of operation procedures from human factors viewpoint. They developed both writer’s guides and process guides for emergency operating procedures. Reviewing the present emergency operating procedures revealed that there were some mistakes in the documents such as unclear expressions, unsuitable terms, omission of detailed items, frequent use of negative expressions, omission of reference, omission of important numerical expressions and illogical context. It was concluded that the writer’s guide and process guides lack of some important aspects of human factors guideline to enhance readability and simplicity.
모델휴먼프로세서를 활용한 인지과정 시뮬레이터 구축에 관한 연구
이동하,나윤균 한국산업안전학회 1998 한국안전학회지 Vol.13 No.4
Though limited, Model Human Processor (MHP) has been used to explain the complex users' behaviors during human-computer interactions in a simplified manner. MHP consists of perceptual, cognitive and motor systems, each with processors and memories interacting with each other in serial or parallel mode. The important parameters of memory include the storage capacity, the decay time, and the code type of a memorized item. The important parameter of a processor is the cycle time. Using these features of the model, this study developed a computerized cognitive process simulator to predict the cognitive process time of a class match task process. An experimental validity test result showed that the mean prediction time for cognitive process of the class match task simulated 50 times by the simulator was consistent with the mean cognitive process time of the same task performed by 37 subjects. Animation of the data flow during the class match task simulation will help understand the invisible human cognitive process.