• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.770-776
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• 2021

Positioning systems have been actively researched and developed over the past few years and have been used in many applications. This paper presents a method to determine a location in a large space using a sensor system consisting of an accelerometer and a single-axis gyroscope. In particular, to consider usability, a sensor device was loosely worn on the waist so that the experimental data could be used in practical applications. Based on the experimental results of circular tracks with radiuses of 1m and 3m, in this paper, an algorithm using the threshold of rotation angle was proposed and applied to the experimental results. A tracking experiment was performed on the grid-pattern track model. For raw sensor data, the average deviation between the final tracking point and the target point was approximately 15.2 m, which could be reduced to approximately 4.0 m using an algorithm applying the rotation angle threshold.

• Journal of Korean Society of Forest Science
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• v.100 no.1
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• pp.79-87
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• 2011

This study was conducted to identify the relationship between urban heat island effect and forest, analyzing electricity consumption model and temperature change model. Electricity consumption model was adopted to clarify a role of forests in alleviating the heat island effect at the national scale, while temperature change model was adopted to clarify a role of forests in mitigating urban heat island effect on metropolis with using econometric analysis. The analysis results from both models clearly show a negative correlation between the urban forests within living areas and heat island effect. In particular, when urban forests within living area per person increases by $1m^2$, the average municipal electricity consumption decreases by 0.02MWh and the summer daytime temperature for metropolitan cities decreases by $1.15^{\circ}C$.

• The Korean Journal of Applied Statistics
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• v.34 no.3
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• pp.389-399
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• 2021

In recent years, word embedding has been a popular field of natural language processing research and a skip-gram has become one successful word embedding method. It assigns a word embedding vector to each word using contexts, which provides an effective way to analyze text data. However, due to the limitation of vector space model, primary word embedding methods assume that every word only have a single meaning. As one faces multi-sense words, that is, words with more than one meaning, in reality, Neelakantan (2014) proposed a multi-sense skip-gram (MSSG) to find embedding vectors corresponding to the each senses of a multi-sense word using a clustering method. In this paper, we propose a modified method of the MSSG to improve statistical accuracy. Moreover, we propose a data-adaptive choice of the number of clusters, that is, the number of meanings for a multi-sense word. Some numerical evidence is given by conducting real data-based simulations.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.32 no.1
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• pp.335-360
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• 2021

This study aimed to develop self-diagnosis tools to evaluate the common competence level of public library librarians, apply them to actual public library librarians, and analyze the factors of competency value evaluation through empirical research methods. To this end, the study modify the existing capacity value evaluation indicators of librarians from a public library perspective and conducted a survey to self-diagnose the common capabilities of public library librarians. As the results of analysis showed that librarians of public libraries themselves think that the level of core competence that professional librarians should acquire is relatively higher than the average. Among the overall capabilities of librarians, the average of the 'librarians' behavior and attitude' area was the highest, followed by the 'librarians' skill' and 'librarian's knowledge' areas. The study suggested to strengthen the capacity of public library librarians for various duties, the re-education system for librarians should be established, and a systematic system for promoting librarians' duties as professionals, and a personnel system for professional development.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1539-1545
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• 2020

With the advent of the ubiquitous era due to the development of science and technology in the modern society, interest in data generated in the IoT environment has increased socially. However, the existing IoT platform has difficulties in processing inquiry requests that require large amounts of throughput, such as statistical processing of large amounts of data. Accordingly, in this paper, we propose an IoT platform that can flexibly accommodate requirements for inquiry requests and improve inquiry performance. The platform proposed in this paper showed a performance improvement of about 1200 times in terms of average response time by introducing a separate read database. By separating the object model into a command side and a query side, the complexity of the object is reduced to meet the various demands on the platform. It was made to allow quick acceptance of the matter.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.1
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• pp.41-52
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• 2021

During atmospheric ascent of a launch vehicle, airborne acoustic loads act on the vehicle and its effect becomes pronounced at transonic speed. In the present study, acoustic loads acting on a hammerhead launch vehicle at a transonic speed have been analyzed using ��-ω SST based IDDES and the results including mean Cp, Cprms, and PSD are compared to available wind-tunnel test data. Mesh dependency of IDDES results has been investigated and it has been concluded that with an appropriate turbulence scale-resolving computational mesh, the characteristic flow features around a transonic hammerhead launch vehicle such as separated shear flow at fairing shoulder and its reattachment on rear body as well as large pressure fluctuation in the region of separated flow behind the boat-tail can be predicted with reasonable accuracy for engineering purposes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.1
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• pp.58-63
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• 2022

The daily number of confirmed cases of Coronavirus disease 2019(COVID-19) ranges between 1,000 and 2,000. Despite higher vaccination rates, the number of confirmed cases continues to increase. The Mu variant of COVID-19 reported in some countries by WHO has been identified in Korea. In this study, we predicted the number of confirmed COVID-19 cases in Korea using the SARIMA for the Covid-19 prevention strategy. Trends and seasonality were observed in the data, and the ADF Test and KPSS Test was used accordingly. Order determination of the SARIMA(p,d,q)(P, D, Q, S) model helped in extracting the values of p, d, q, P, D, and Q parameters. After deducing the p and q parameters using ACF and PACF, the data were transformed and schematized into stationary forms through difference, log transformation, and seasonality removal. If seasonality appears, first determine S, then SARIMA P, D, Q, and finally determine ARIMA p, d, q using ACF and PACF for the order excluding seasonality.

• Journal of Korea Society of Industrial Information Systems
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• v.27 no.2
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• pp.11-24
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• 2022

For the questions asked for LMS-based online evaluation the professor directly set exam questions, or use the automatic question-taking method according to the level of difficulty using the question bank divided by category. Among them, it is important to manage the difficulty of questions in an objective and efficient way, above all, in the automatic question-taking method according to difficulty. Because the questions presented to the evaluators may be different. In this paper, we propose an difficulty re-adjustment algorithm that considers not only the correct rate of a problem but also the time taken to solve the problem. For this, a logistic regression classification algorithm was used of machine learning, and a reference threshold was set based on the predicted probability value of the learning model and used to readjust the difficulty of each item. As a result, it was confirmed that there were many changes in the difficulty of each item that depended only on the existing correct rate. Also, as a result of performing group evaluation using the adjustment difficulty problem, it was confirmed that the average score improved in most groups compared to the difficulty problem based on the percentage of correct answers.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.2
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• pp.168-175
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• 2022

With the recent development of nanotechnology, its application in the field of construction materials is continuously increasing. However, until now, studies on the bond characteristics of concrete and rebar for applying high-strength lightweight concrete with a compressive strength of 50 MPa and a unit weight of 16 kN/m³ to structural members are lacking. Therefore, in this paper, 81 specimens of high-strength lightweight concrete with a compressive strength of 50 MPa and a unit weight of about 16 kN/m³ were fabricated and a direct pull-out tests were performed. The design code for the bond strength of ACI-408R and the experimental results are shown to be relatively similar, and as a result of the CEB-FIP and modified CMR bond behavior models through statistical analysis, it is shown to describe well on average.

• Journal of the Korea Society of Computer and Information
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• v.28 no.1
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• pp.39-47
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• 2023

In this paper, we propose a method to measure the similarity between golf swings in videos. As it is known that deep learning-based artificial intelligence technology is effective in the field of computer vision, attempts to utilize artificial intelligence in video-based sports data analysis are increasing. In this study, the joint coordinates of a person in a golf swing video were obtained using a deep learning-based pose estimation model, and based on this, the similarity of each swing segment was measured. For the evaluation of the proposed method, driver swing videos from the GolfDB dataset were used. As a result of measuring swing similarity by pairing swing videos of a total of 36 players, 26 players evaluated that their other swing sequence was the most similar, and the average ranking of similarity was confirmed to be about 5th. This ensured that the similarity could be measured in detail even when the motion was performed similarly.