• Journal of the Korea Society for Simulation
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• v.13 no.4
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• pp.1-16
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• 2004

The modelling and simulation of the activation process for the heart system is meaningful to understand special excitatory and conductive system in the heart and to study cardiac functions because the heart activation conducts through this system. This thesis proposes two dimensional cellular automaton(CA) model for the activation process of the myocardium and conducted simulation by means of discrete time and discrete event algorithm. In the model, cells are classified into anatomically similar characteristic parts of the heart and each of cells has a set of cells with preassigned properties. Each cell in this model has state variables to represent the state of the cell and has some state transition rules to change values of state variables executed by state transition function. The state transition rule is simple as follows. First, the myocardium cell at rest stay in passive state. Second, if any one of neighborhood cell in the myocardium cell is active state then the state is change from passive to active state. Third, if cell's state is an active then automatically go to the refractory state after activation phase. Four, if cell's state is refractory then automatically go to the passive state after refractory phase. These state transition is processed repeatedly in all cells through the termination of simulation.

• Journal of Applied Reliability
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• v.13 no.2
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• pp.117-127
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• 2013

In this paper, we studied the correlation between the activation energy($E_a$) of the raw materials and the structural characteristics of the White LED PKGs. The samples used in the study were composed of low power LED 3type and high power LED 5type. To calculate the activation energy($E_a$) of the White LED PKGs conducted three conditions of high temperature operation test based on the Arrhenius model. The number of samples used in the experiment is 10, respectively. The $T_j$ of Conditions and target specifics expressed $T_{j1}$, $T_{j2}$, $T_{j3}$. The activation energy ($E_a$) of the samples was calculated based on the value of the actually measured lifetime. We investigated the correlation between the activation energy ($E_a$) of the raw materials and the structural characteristics of the White LED PKGs. As a result, White LED PKGs activation energy($E_a$) value was confirmed that the material properties affected more than the structural characteristics of the LED PKGs and we found that activation energy of each LED Model has difference. Normally, The activation energy of phosphor of YAG type was indicated from 0.21 to 0.25[eV] and Silicate type was indicated from 0.12 to 0.16[eV]. According to the results, we confirmed that the activation energy of phosphor of YAG type is higher more than The activation energy of phosphor of Silicate type.

• Journal of the Ergonomics Society of Korea
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• v.26 no.4
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• pp.135-142
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• 2007

Icon conveys symbolic information which they have become ubiquitous as main element of GUI. However, users often cannot intuitively understand its functional meanings. Icon has to be designed for users to easily understand functional meanings. In order to evaluate icon, the spreading activation model can be used to effectively understand the process of information retrieval. In asymmetric spreading activation model is that in the two nodes the degree of spreading activation is different according to direction. Thus, asymmetric spreading activation theory was performed evaluating the strength of association when users see visual image to associate their verbal meaning (visual image - verbal meaning pair) and users see verbal meaning to associate their visual image (verbal meaning - visual image pair). According to the direction, this study hypothesizes that the well-designed icons have symmetric relationship rather than asymmetric relationship between the two pairs. The strength of association is measured through the reaction time and the accuracy rate. In performing SAT (spreading activation test), the ten icons were selected as word processing software icons. After first SAT, newly designed icons were developed based on Korean mental model, and second SAT was conducted using them. The results showed that the accuracy rate of newly designed icon has been improved. Also there is significant difference of reaction time between current icons and newly designed icons. Well-designed icon is confirmed that the strength of association relationship arises symmetrically rather than asymmetrically between the two pairs. User centered icons could be designed by improving the strength of association between the two pairs. Asymmetric SAT evaluates the strength of the association between the visual image and the verbal meanings to contribute to the development of icon which it related to human's association structure.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.1
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• pp.17-26
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• 2004

In this study, the usability evaluation of a menu-structure was performed using spreading activation model with respect to human's memory retrieval. Spreading Activation Model is effectively used to understand the process of information retrieval, so it can be used as a theoretical background for modeling of the process of human's information retrieval. For spreading activation test (SAT), subjects were presented with 67 pairs of menu titles, which consist of a menu title in the high level menu item and a menu title for the next lower level menu item, from Korea University's web site. For performance tests, three scenarios were developed with longer reaction times and ambiguous associations found in the SAT to reflect the existing problems of the website. As a result, the SAT was found to bean effective tool to enhance the website usability because the SAT could bea substitute for the performance test with a high correlation $({\rho}=0.735,\;{\alpha}=0.05)$. After remaining menu titles with slow reaction times and ambiguous associations found in SAT, the website usability was significantly improved with faster reaction times and less ambiguous associations proven with smaller number of web-page visits. Therefore, the SAT could be used as a methodology to design and evaluate the user-centered menu structure related to human's association structure.

• The Korea Journal of Herbology
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• v.28 no.2
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• pp.1-7
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• 2013

Objectives : Sesamin, a major lignan in sesame seeds, has been reported to have neuroprotective effects against in vitro ischemia and in vivo MCAo-reperfusion cerebral ischemia model, however, there is no reports in an in vivo global cerebral ischemia model. The purpose of the study was to investigate the neuroprotective effect of sesamin in global cerebral ischemia induced by four-vessel occlusion (4-VO) in rats through inhibition of microglial activation in this model. Methods : The neuroprotective effects were investigated using a 10 min of 4-VO ischemia rat model by measuring intact pyramidal neurons in the CA1 region of the hippocampus using Nissle staining. The antiinflammatory or reducing neurotoxicity effect was investigated using immunohistochemisty, RT-PCR and western blot analysis of inflammatory or neurotoxic mediators. Results : Intraperitoneal injection of sesamin at doses of 0.3, 1.0, 3.0, and 10.0 mg/kg at 0 min and 90 min after ischemia conferred 26.6%, 30.1%, 42.5%, and 30.5% neuroprotection, respectively, compared to the vehicle-treated control group. A 3.0 mg/kg dose of sesamin inhibited microglia activation and consequently, cyclooxygenase-2, inducible nitric oxide, and interleukine-$1{\beta}$ expressions at 48 h after reperfusion. Conclusions : Sesamin protects neuronal cell death through inhibition of microglial activation or the production of neurotoxic metabolites and proinflammatory mediators by microglia such as COX-2, iNOS and IL-$1{\beta}$ in global cerebral ischemia.

• East Asian mathematical journal
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• v.38 no.4
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• pp.497-516
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• 2022

In this study, we tried to devise a method to activate meta-affect in the aspect of supporting mathematics teaching and learning according to the need to find specific strategies and teaching and learning methods to activate learners' meta-affect in mathematics subjects, which are highly influenced by psychological factors. To this end, the definitional and conceptual elements of meta-affect which are the basis of this study, were identified from previous studies. Reflecting these factors, a teaching and learning model that activates meta-affect was devised, and a meta-affect activation strategy applied in the model was constructed. The mathematics teaching and learning model that activates meta-affect developed in this study was refined by verifying its suitability and convenience in the field through expert advice and application of actual mathematics classes. The developed model is meaningful in that it proposed a variety of practical teaching and learning methods that activate the meta-affect of learners in a mathematical learning situation.

• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.407-412
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• 1994

This paper describes the construction of an anisotropic three dimensional ventricular model based on the bidomain model. The cardiac activation process in the normal cardiac cell and the myocardial ischemic cell are simulated by the Huygen's principle. The depolarization process in the myocardial ischemia displays the delayed activation compared to the normal state. The repolarization process is simulated by the myocardial potential at the arbitrary ellapsed time after activation process. Using the potential data, the equivalent cardiac source at the arbitrary time can be computed. In conclusion, this simulation suggests the possibilities of the depolarization and the repolarization process in the normal and abnormal myocardiac cells.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1996.11a
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• pp.15-18
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• 1996

A general description of sprinkler activation time in compartment-fire-generated smoke layers is made. For calculation of the time hot layer temperature is obtained from two-layer zonal model and time constant of sprinkler is measured. Upper-layer thickness at the instant of sprinkler activation is also presented with changes of opening area. The outputs of the present study provide inputs for the interaction modeling of sprinkler spray and compartment fire environment, which simulates fire suppression phenomena.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.656-658
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• 1999

This paper presents musculotendon model to show the decline in muscle force during functional electrical stimulation (FES). It represent muscle activation and contraction concepts including muscle fatigue. A muscle fatigue term in activation dynamics as a function of the intracellular acidification and the pulsewidth of stimulation pulses change activation to decline muscle force. The computer simulation shows that muscle force decline in stimulation time.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.82-86
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• 1995

Using electrocardiography is a common method to diagnose heart disease, Modeling and simulation of activation process for the heart system is useful to understand electrocardiography. This paper proposes a two-dimensional cellular automata model for the activation process of the ventricles. The model represents the geometry of the ventricles by the ellipsoidal shape in two dimension. In the model, ventricles are divided into four layers, each of which has a set of cells with preassigned properties. The proposed model takes Into account the local orientation of the myocardial fibers and their distributed velocity, and refractory period. Simulation experiment is performed to measure activation potential for each cell in each layer within the ventricles.