• Journal of Power Electronics
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• v.18 no.6
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• pp.1901-1911
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• 2018

This study presents a circuit model for simulating the switching transients of insulated-gate bipolar transistors (IGBTs) with inductive load switching. The modeling approach used in this study considers the behavior of IGBTs and freewheeling diodes during the transient process and ignores the complex semiconductor physics-based relationships and parameters. The proposed circuit model can accurately simulate the switching behavior due to the detailed consideration of device-circuit interactions and the nonlinear nature of model parameters, such as internal capacitances. The developed model is incorporated in an IGBT loss calculation module of an electromagnetic transient simulation program to enable the estimation of switching losses in voltage source converters embedded in large power systems.

• Journal of the Korea Society of Computer and Information
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• v.24 no.2
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• pp.17-24
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• 2019

In this paper, we propose a new model for predicting effective Win/Loss in professional baseball game in Korea using machine learning technique. we used basic baseball data and Sabermetrics data, which are highly correlated with score to predict and we used the deep learning technique to learn based on supervised learning. The Drop-Out algorithm and the ReLu activation function In the trained neural network, the expected odds was calculated using the predictions of the team's expected scores and expected loss. The team with the higher expected rate of victory was predicted as the winning team. In order to verify the effectiveness of the proposed model, we compared the actual percentage of win, pythagorean expectation, and win percentage of the proposed model.

• International Journal of Computer Science & Network Security
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• v.21 no.6
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• pp.54-60
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• 2021

Monte-Carlo GO is a computer GO program that is sufficiently competent without using knowledge expressions of IGO. Although it is computationally intensive, the computational complexity can be reduced by properly pruning the IGO game tree. Here, I achieve this by using a potential model based on the knowledge expressions of IGO. The potential model treats GO stones as potentials. A specific potential distribution on the GO board results from a unique arrangement of stones on the board. Pruning using the potential model categorizes legal moves into effective and ineffective moves in accordance with the potential threshold. Here, certain pruning strategies based on potentials and potential gradients are experimentally evaluated. For different-sized boards, including an official-sized board, the effects of pruning strategies are evaluated in terms of their robustness. I successfully demonstrate pruning using a potential model to reduce the computational complexity of GO as well as the robustness of this effect across different-sized boards.

• International Journal of Computer Science & Network Security
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• v.21 no.3
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• pp.153-164
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• 2021

The increasing importance of such fields as embedded systems, pervasive computing, and hybrid systems control is increasing attention to the time-dependent aspects of system modeling. In this paper, we focus on modeling conceptual time. Conceptual time is time represented in conceptual modeling, where the notion of time does not always play a major role. Time modeling in computing is far from exhibiting a unified and comprehensive framework, and is often handled in an ad hoc manner. This paper contributes to the establishment of a broader understanding of time in conceptual modeling based on a software and system engineering model denoted thinging machine (TM). TM modeling is founded on a one-category ontology called a thimac (thing/machine) that is used to elaborate the design and analysis of ontological presumptions. The issue under study is a sample of abstract modeling domains as exemplified by time. The goal is to provide better understanding of the TM model by supplementing it with a conceptualization of time aspects. The results reveal new characteristics of time and related notions such as space, events, and system behavior.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.2
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• pp.405-423
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• 2022

The distance vector-hop (DV-Hop) is one of the emblematic algorithms that use node connectivity for locating, which often accompanies by a large positioning error. To reduce positioning error, the bio-inspired algorithm and weight optimization model are introduced to address positioning. Most scholars argue that the weight value decreases as the hop counts increases. However, this point of view ignores the intrinsic relationship between the error and weight. To address this issue, this paper constructs the relationship model between error and hop counts based on actual communication characteristics of sensor nodes in wireless sensor network. Additionally, we prove that the error converges to 1/6CR when the hop count increase and tendency to infinity. Finally, this paper presents a modified error-oriented weight positioning model, and implements it with genetic algorithm. The experimental results demonstrate excellent robustness and error removal.

• Journal of Korea Foundry Society
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• v.20 no.5
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• pp.290-299
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• 2000

A three-dimensional model was developed in order to simulate heat and fluid flow of a continuous casting billet. The model was coded with the general-purpose CFD program FIDAP, using the finite element method. The present model consists of 2 individual calculation schemes, named model 1 and model 2. Mold region only was calculated to check the pouring stream through submerged nozzle with model 1. Entire region, which consists of mold, secondary cooling, radiation cooling was calculated to predict crater end position, temperature profile and solid shell profile(model 2). Standard $k-{\bullet}\hat{A}$ turbulence model has been applied to simulate the turbulent flow induced by submerged nozzle. Enthalpy method was adopted for the latent heat of solidification. Fluid flow in mushy zone was treated using variable viscosity approach. The more casting speed and superheat increased, the more metallurgical length increased. The shell thickness at the mold exit is proved to be mainly controlled by superheat by the present simulation. It may be concluded that the present model can be successfully applied far the prediction of heat and fluid flow behavior in the continuous casting process.

• Agricultural and Biosystems Engineering
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• v.4 no.1
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• pp.34-38
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• 2003

A mathematical model was developed for estimating the mechanical interrelation between characteristics of soil and main design factors of a tracked vehicle, and predicting the tractive performance of the tracked vehicle. Based on the mathematical model, a computer simulation program (TPPMTV) was developed in the study. The model considered the continuous change in tension for the whole track of a tracked vehicle, the analysis of shape and tension of the track segment between sprocket and first roadwheel, and the side thrust on both sides of grouser by the active earth pressure theory in predicting the tractive performance of a tracked vehicle. Also, the model contained not only sinkage depth of the track but the pressure distribution under the track in analyzing the side thrust. The effectiveness of the developed model was verified by performing the draw bar pull tests with a tracked vehicle reconstructed for test in loam soil with moisture content of 18.92％. The predicted drawbar pulls by the model were well matched to the measured ones. Such results implied that the model developed in the study could estimate the drawbar pulls well at various soil conditions, and would be very useful as a simulation tool for designing a tracked vehicle and predicting its tractive performance.

• Journal of Computing Science and Engineering
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• v.8 no.1
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• pp.17-24
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• 2014

In this paper, we propose a new implementation of a failure detector. The implementation uses a dual model of heartbeat and interaction. First, the heartbeat model is adopted to shorten the detection time, if the detection process does not receive the heartbeat message in the expected time. The interaction model is then used to check the process further. The expected time is calculated using the exponential smoothing method. Exponential smoothing can be used to estimate the next arrival time not only in the random data, but also in the data of linear trends. It is proven that the new detector in the paper can eventually be a perfect detector.

• Journal of Korea Technology Innovation Society
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• v.3 no.3
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• pp.85-101
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• 2000

The purpose of this study is to test whether prices of personal computers reflect their varying degrees of non-marketable characteristics including after-sales service. This purpose is carried out using the hedonic price model. In this paper, we estimated 74 functional forms of hedonic price model using the quadratic Box-Cox transformation function and selected one based on the three criteria: expected signs, the statistical significance of estimated coefficients, and goodness of fit in terms of root-mean-square-percentage-error. In this study, we found hat as the after-sales service level increases the price of the personal computer increases. This result is consistent with the hypothesis that the less after-sales service offered with a personal computer, the less consumers are willing to pay for the personal computer, when all else remain constant. This finding shows that since the market works indirectly to influence pricing, the need to rely on consumer protection legislation to guarantee after-sales service is lessened. This study also found that after-sales service supported by each personal computer producer is not a free service, thus produces have a profit incentive for providing after-sales service.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.11
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• pp.2813-2826
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• 2012

Various stakeholders are involved in the creation of software projects. In general, the higher the number of stakeholders involved during the requirements elicitation phase, the better are the chances of success for the project. However, it is rather difficult to consider the opinion of all the stakeholders owing to constraints on time and resources. Furthermore, conflicts between stakeholders can become inevitable when the number of stakeholders increases. Thus, the identification of key stakeholders is an important factor in ensuring the success of a project. In this paper, a methodical stakeholder conflict resolution model (s-CRM) is proposed by considering an actual industrial case study. The proposed model uses information gain based on entropy when measuring the impurity of information. We believe that the proposed s-CRM is effective in identifying the key stakeholders and in intuitively indicating those stakeholders whose elicited requirements need to be weighted. In addition, the model provides a solution for conflicts among stakeholders during requirements engineering.