• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.270-272
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• 2021

최근 영상신호처리에 대한 딥러닝 기술이 비약적으로 발전함에 따라 다양한 방면으로 시도되고 있다. 그 중 machine level vision 에서 인지 기능을 하는 optical flow 를 end-to-end 학습 방식으로 제시하여 고성능 결과물을 도출하는 RAFT(Recurrent All-pairs Field Transform for Optical flow, 2020)에 대해 분석하고자 한다. RAFT 는 입력된 두 이미지에 대한 4D correlation volume 을 구축하여 모든 픽셀에 대한 정보를 사용한다. 또한, recurrent neural network 에서 차용한 반복적인 연산 학습 구조를 통하여 결과물인 flow field 의 정확도를 높인다. 해당 모델은 stereo dataset 을 사용하는 다른 모델에 비해 학습 시간이 짧고 용량이 작으면서 error rate 은 낮은 모습을 보인다. 현재 많은 연구에서 optical flow 를 접목하려는 움직임을 보이고 있고 다양하게 활용될 가능성이 다분하다는 점에서 주목할 가치가 있다.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.44-48
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• 2015

Housing price is a key indicator of housing demand. Actual Transaction Price Index of Apartment (ATPIA) released by Korea Appraisal Board is useful to understand the current level of housing price, but it does not forecast future prices. Big data such as the frequency of internet search queries is more accessible and faster than ever. Forecasting future housing demand through big data will be very helpful in housing market. The objective of this study is to develop a forecasting model of ATPIA as a part of forecasting housing demand. For forecasting, a concept of time shift was applied in the model. As a result, the forecasting model with the time shift of 5 months shows the highest coefficient of determination, thus selected as the optimal model. The mean error rate is 2.95% which is a quite promising result.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3628-3638
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• 2023

This paper uses 135 Licensed Operator Event Reports (LOER) from Chinese nuclear plants to analyze how safety culture affects unsafe behaviors in nuclear power plants. On the basis of a modified human factors analysis and classification system (HFACS) framework, structural equation model (SEM) is used to explore the relationship between latent variables at various levels. Correlation tests such as chi-square test are used to analyze the path from safety culture to unsafe behaviors. The role of latent error is clarified. The results show that the ratio of latent errors to active errors is 3.4:1. The key path linking safety culture weaknesses to unsafe behaviors is Organizational Processes → Inadequate Supervision → Physical/Technical Environment → Skill-based Errors. The most influential factors on the latent variables at each level in the HFACS framework are Organizational Processes, Inadequate Supervision, Physical Environment, and Skill-based Errors.

• Journal of Information Processing Systems
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• v.20 no.2
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• pp.173-184
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• 2024

The connected car services are one of the most widely used services in the Internet of Things environment, and they provide numerous services to existing vehicles by connecting them through networks inside and outside the vehicle. However, although vehicle manufacturers are developing services considering the means to secure the connected car services, concerns about the security of the connected car services are growing due to the increasing number of attack cases. In this study, we reviewed the research related to the connected car services that have been announced so far, and we identified the threats that may exist in the connected car services through security threat modeling to improve the fundamental security level of the connected car services. As a result of performing the test to the applications for connected car services developed by four manufacturers, we found that all four companies' applications excessively requested unnecessary permissions for application operation, and the apps did not obfuscate the source code. Additionally, we found that there were still vulnerabilities in application items such as exposing error messages and debugging information.

• Smart Media Journal
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• v.13 no.6
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• pp.62-71
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• 2024

This study applies topic modeling to uncover user experience and app issues expressed in users' online reviews of a fan community platform, Weverse on Google Play Store. It allows us to identify the features which need to be improved to enhance user experience or need to be maintained and leveraged to attract more users. Therefore, we collect 88,068 first-level English online reviews of Weverse on Google Play Store with Google-Play-Scraper tool. After the initial preprocessing step, a dataset of 31,861 online reviews is analyzed using Latent Dirichlet Allocation (LDA) topic modeling with Gensim library in Python. There are 5 topics explored in this study which highlight significant issues such as network connection error, delayed notification, and incorrect translation. Besides, the result revealed the app's effectiveness in fostering not only interaction between fans and artists but also fans' mutual relationships. Consequently, the business can strengthen user engagement and loyalty by addressing the identified drawbacks and leveraging the platform for user communication.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.228-235
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• 2024

Battery use is increasing worldwide to achieve carbon neutrality and improve energy efficiency, but batteries are a finite resource and their application is determined by capacity and specifications. Battery performance deteriorates as the number of uses increases. A certain level of battery performance degradation has become an issue in the field of reuse and recycling, and various studies are being conducted on reuse to solve power shortages. Waste batteries from electric vehicles are suitable for building ESS based on reusable batteries, and for stable use, technical skills are needed to accurately predict battery life and determine status information. Predicting battery life and determining status information are difficult due to non-linearity due to internal structure or chemical changes. In this paper, we manufactured a modular internal resistance measuring device and compared the measured values with Hioki equipment to minimize the error rate through a correction method. As a result of testing Hioki equipment and modular measuring instruments to ensure efficiency and safety based on reusable batteries, an accuracy of over 95% was confirmed.

• International Journal of Computer Science & Network Security
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• v.24 no.10
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• pp.147-153
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• 2024

The problem of handling uncertain data has been attracting the attention of researchers. This paper mainly focuses on uncertain data clustering and noise data streams. Therefore, we will provide a framework to realize the effect of uncertainty. Nowadays, a large number of tenders are present which measure the data roughly. As, sensors normally have distortion in their results cause of the imprecisions transmission in data and retrieval. Mostly these errors are identified. This information is used for minimizing process to advance results according to quality. In this paper, we compare general methods of monitor uncertainty, which have described in the different research papers.

• Journal of the Korea Society of Computer and Information
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• v.16 no.12
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• pp.175-185
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• 2011

The threshold level of a receiver is analyzed for the simplification of system and the improvement of upstream data ratios in optical subscriber network of which the upstream date rate and the optical transmitted power are changed to meet the requested BER (Bit Error Rate) defined per interactive multimedia services. In asynchronous optical subscriber network of which the upstream to downstream data ratios are 1:1/2, 1:1/4, 1:1/8 and 1:1/16 with manchester coded downstream and NRZ (Non Return to Zero) downstream re-modulation, the BER performance is theoretically analyzed and it is performed by simulation with MATLAB according to the four types of downstream data for four models. The results have shown that in the cases which the upstream to downstream data ratios are 1:1/4, 1:1/8 and 1:1/16 the conventional receiver with threshold level of 1/2 can be applied regardless of average received optical powers and the BER is not much deteriorated compared with using the optimal threshold level. In the case that the upstream to downstream data ratio is 1:1/2 the threshold level in an optical receiver could be fixed at 1/3 and the BER is not much deteriorated compared with using the optimal threshold level as the average received optical power increases.

• Korean journal of applied entomology
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• v.19 no.4 s.45
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• pp.212-220
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• 1980

The purpose of this study is to establish a standard amount of pesticide per unit area of the lumber over the sea level. This establishment is required in applying the sea water dipping disinfection method to the imported soft woods to control the pests living on the surface of the lumber. The major findings of this study are as follows; 1. The average length and diameter of the imported soft wood was respectively 11.12m and 76.46Cm. 2. The average cubic content of the lumber over the sea level to the whole cubic content was 20.82 percent. 3. The ratio of the lumber over the sea level to the whole cubic content was 2.3356 at the $95\%$ significance level. 4. The sampling error of the ratio of the area of the lumber over the sea level to the cubic content was lower in the case of the pieces of lumber in a vessel than the average between ten tressels. 5. The optimum amount of pesticide spray per $1\;M^2$ of the soft wood was 0.298 cc in the case of using the hand spray, but 0.245 cc the motor spray. 6. For example, in the case of applying the sea water dipping disinfection method to the 5,000 $M^3$ of the imported soft wood, the required amount of pesticide with a motor spray can be estimated as follow. $$5,000\;M^3\times2.333=11,678\;M^2$$ $$11,678M^2\times0.295=3,445cc$$.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.2
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• pp.353-370
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• 2016

This study examined elementary mathematics teacher's guidebook to determine the inclusion level of 11 critical features of evidence based instruction. And the inclusion level of the features in teacher's guidebook were interpreted as 'Low', 'Middle' and 'High'. The results are as followings. First, The overall inclusion level of the features in teacher's guidebook is 'Middle' The inclusion level of the features in teacher's guidebook for 1st, 2nd, 3rd and 4th were 'Middle' but for 5th and 6th were 'Low'. Second, the inclusion level of the features 'Clarity of Objective', 'Single Concepts and Skill Taught', 'Use of Manipulatives and Representation', 'Explicit Instruction', 'Provision of Examples for new concepts and skill', 'Adequate Independent Practice Opportunities' and 'Progress Monitoring' were 'Middle' The inclusion level of the features 'Review of Prerequisite Mathematical Skills', 'Error correction and Corrective Feedback' and 'Instruction of Strategies' were 'Low'. And discussed the results.