• Journal of Internet Computing and Services
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• v.23 no.4
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• pp.45-55
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• 2022

The size of the cryptocurrency market is growing. For example, market capitalization of bitcoin exceeded 500 trillion won. Accordingly, many studies have been conducted to predict the price of cryptocurrency, and most of them have similar methodology of predicting stock prices. However, unlike stock price predictions, machine learning become best model in cryptocurrency price predictions, conceptually cryptocurrency has no passive income from ownership, and statistically, cryptocurrency has at least three times higher liquidity than stocks. Thats why we argue that a methodology different from stock price prediction should be applied to cryptocurrency price prediction studies. We propose Reverse Walk-forward Validation (RWFV), which modifies Walk-forward Validation (WFV). Unlike WFV, RWFV measures accuracy for Validation by pinning the Validation dataset directly in front of the Test dataset in time series, and gradually increasing the size of the Training dataset in front of it in time series. Train data were cut according to the size of the Train dataset with the highest accuracy among all measured Validation accuracy, and then combined with Validation data to measure the accuracy of the Test data. Logistic regression analysis and Support Vector Machine (SVM) were used as the analysis model, and various algorithms and parameters such as L1, L2, rbf, and poly were applied for the reliability of our proposed RWFV. As a result, it was confirmed that all analysis models showed improved accuracy compared to existing studies, and on average, the accuracy increased by 1.23%p. This is a significant improvement in accuracy, given that most of the accuracy of cryptocurrency price prediction remains between 50% and 60% through previous studies.

• Journal of Korea Port Economic Association
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• v.28 no.1
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• pp.263-288
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• 2012

This study aims to define which factors will contribute to vitalization of Saemangeum New Port to secure international competitiveness in order to attract international shipping companies, shippers and forwarders in constructing Saemangeum New Port, and to propose subsequent implications. For research methods of the current study, a factor analysis and a decision making method of analytic hierarchy process(AHP) were used. Through precedent studies, total 11 measuring variables were selected including short entrance and exit channels, main infrastructure development project, tax cut and deregulation, and through a factor analysis, total 3 high rank evaluation factors including 'location and facilities', 'surrounding infrastructure and hydrophile property', and 'local policy and environment'. Analysis results summarizing a test of reliability of measuring variables in this study indicate that as Cronbach alpha coefficient of total 11 measuring variables were turned out to be over 0.8, it is surpassing general average 0.6, which means there is reliability.

• Journal of Korea Water Resources Association
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• v.55 no.spc1
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• pp.1295-1303
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• 2022

As the role of water distribution networks (WDNs) becomes more important, identifying abnormal events (e.g., pipe burst) rapidly and accurately is required. Since existing approaches such as field equipment-based detection methods have several limitations, model-based methods (e.g., machine learning based detection model) that identify abnormal events using hydraulic simulation models have been developed. However, no previous work has examined the impact of data uncertainties on the results. Thus, this study compares the effects of measurement error-induced pressure data uncertainty in WDNs. An artificial neural network (ANN) is used to predict nodal pressures and measurement errors are generated by using cumulative density function inverse sampling method that follows Gaussian distribution. Total of nine conditions (3 input datasets × 3 output datasets) are considered in the ANN model to investigate the impact of measurement error size on the prediction results. The results have shown that higher data uncertainty decreased ANN model's prediction accuracy. Also, the measurement error of output data had more impact on the model performance than input data that for a same measurement error size on the input and output data, the prediction accuracy was 72.25% and 38.61%, respectively. Thus, to increase ANN models prediction performance, reducing the magnitude of measurement errors of the output pressure node is considered to be more important than input node.

• Journal of The Korean Association For Science Education
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• v.18 no.2
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• pp.127-136
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• 1998

The purpose of this study was to develop, field test an instrument to assess secondary school students' conceptions of the nature of science. The instrument named Philosophical Perspectives Probe(PPP) is a pool of 24 multiple-choice items that address a wide range of philosophical topics of science. The statements and the choices of this instrument were derived from an analysis of various philosophical positions. The main philosophical systems of the instrument are inductivism, falsificationism, and relativism, respectively. Major distinctions depend on the issues of the criteria of demarcation, patterns of scienctific change, epistemological status of scientific knowledge, and the scientific methods. The researchers also offer teachers a new way of assessing and interpreting their students' conceptions on a wide variety of topics related to the nature of science.

• The Journal of Society for e-Business Studies
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• v.16 no.2
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• pp.129-142
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• 2011

Traditionally research in Service Oriented Architecture(SOA) security has focused primarily on exploiting standards and solutions separately. There exists no unified methodology for SOA security to manage risks at the enterprise level. It needs to analyze preliminarily security threats and to manage enterprise risks by identifying vulnerabilities of SOA. In this paper, we propose a metric-based vulnerability assessment method using dynamic properties of services in SOA. The method is to assess vulnerability at the architecture level as well as the service level by measuring run-time dependency between services. The run-time dependency between services is an important characteristic to understand which services are affected by a vulnerable service. All services which directly or indirectly depend on the vulnerable service are exposed to the risk. Thus run-time dependency is a good indicator of vulnerability of SOA.

• Journal of Korea Game Society
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• v.15 no.4
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• pp.121-132
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• 2015

This study suggests a design for an analytical software program and method for multitasking e-sports viewing through the web using an eye tracking device. To fulfill this task, we designed a Window of Interest (WOI) to measure and record visually on a screen wherever numerous multitasking activities occur. In addition, we developed an OBS (Opensource Broadcaster Software) plug-in that records and streams participant viewing behavior patterns in real time. The purpose of this study is as follows. First, unlike existing tools that limit web interface recording to still images, the developed tool can record dynamically via media such as videos. Second, when several windows are processed on a screen, the tool can accurately record the gaze positions of the participants. Lastly, the tool can enhance the objective validity of the data as it can be implemented in natural situations. Therefore, this study can trace natural viewing patterns and behavior as we do not create artificial experimental environments and stimuli.

• The Mathematical Education
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• v.58 no.3
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• pp.367-381
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• 2019

This investigation engaged elementary and middle school pre-service teachers in a task of modeling and explaining the magnitude of $0.14m^2$ and examined their responses. The study analyzed both successful and unsuccessful responses in order to reflect on the patterns of misconceptions relative to pre-service teachers' prior knowledge. The findings suggest a need to promote opportunities for pre-service teachers to make connections between different domains through meaningful tasks, to reason abstractly and quantitatively, to use proper language, and to refine conceptual understanding. While mathematics teacher educators (MTEs) could use such mathematical tasks to identify the mathematical content needs of pre-service teachers, MTEs generally use instructional time to connect content and pedagogy. More importantly, an early and consistent exposure to a combined experience of mathematics and pedagogy that connects and deepens key concepts in the program's curriculum is critical in defining the important content knowledge for K-8 mathematics teachers.

• Journal of Korea Water Resources Association
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• v.55 no.7
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• pp.557-563
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• 2022

The rating curve is required to convert measured stage into a discharge and is developed using the measurement. In the development of the rating curve, the segmentation position is determined by considering the hydraulic characteristic and channel shape, and subjective judgment of the Hydrographer may intervene in this process. The segmentation position is so important that it determines the overall form of the rating curve, and the incorrect segmentation can cause errors in the rating curve, especially in extrapolation. In order to develop an accurate rating curve with a small number of measurements, the sections must be divided by considering hydraulic characteristic such as the cross-sectional shape. In this study, hydraulic examination methods such as stage-mean velocity, stage-area, stage-${\sqrt{Q}}$ investigated and supplemented to eliminate subjectivity in segmental positioning. Appropriateness for the segmentation position was verify in consideration of the physical meaning of the rating curve index (c).

• The Journal of Dong Guk Oriental Medicine
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• v.7 no.2
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• pp.27-46
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• 1999

This study was done in order to investigate the object and the method of animal e xperimental thesis on diabetes. The results were obtained as follows: 1. Rat, mouse, kk mouse and rabbit were used for experimental Diabetes single or combine. 2. Alloxan, streptozotocin, interleukin-$1{\beta}$, epinephrine, ethanol and KK mouse were used for inducement of Diabetes. 3. Blood glucose, insulin, body weight, drinking water, urinary volume and the chan ge of Langerhan's islet tissue were first observational items on Diabetes.

• The KIPS Transactions:PartB
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• v.10B no.4
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• pp.473-478
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• 2003

In this paper, we propose the gesture recognition system using a motion information from extracted hand region in complex background image. First of all, we measure entropy for the difference image between continuous frames. Using a color information that is similar to a skin color in candidate region which has high value, we extract hand region only from background image. On the extracted hand region, we detect a contour using the chain code and recognize hand gesture by applying improved centroidal profile method. In the experimental results for 6 kinds of hand gesture, unlike existing methods, we can stably recognize hand gesture in complex background and illumination changes without marker. Also, it shows the recognition rate with more than 95% for person and 90∼100% for each gesture at 15 frames/second.