• Title/Summary/Keyword: combined systems

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An Approach for the Estimation of Mixture Distribution Parameters Using EM Algorithm (복합확률분포의 파라메타 추정을 위한 EM 알고리즘의 적용 연구)

  • Daeyoung Shim;SangGu Kim
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.22 no.4
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    • pp.35-47
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    • 2023
  • Various single probability distributions have been used to represent time headway distributions. However, it has often been difficult to explain the time headway distribution as a single probability distribution on site. This study used the EM algorithm, which is one of the maximum likelihood estimations, for the parameters of combined mixture distributions with a certain relationship between two normal distributions for the time headway of vehicles. The time headway distribution of vehicle arrival is difficult to represent well with previously known single probability distributions. But as a result of this analysis, it can be represented by estimating the parameters of the mixture probability distribution using the EM algorithm. The result of a goodness-of-fit test was statistically significant at a significance level of 1%, which proves the reliability of parameter estimation of the mixture probability distribution using the EM algorithm.

Recognition of Events by Human Motion for Context-aware Computing (상황인식 컴퓨팅을 위한 사람 움직임 이벤트 인식)

  • Cui, Yao-Huan;Shin, Seong-Yoon;Lee, Chang-Woo
    • Journal of the Korea Society of Computer and Information
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    • v.14 no.4
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    • pp.47-57
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    • 2009
  • Event detection and recognition is an active and challenging topic recent in Computer Vision. This paper describes a new method for recognizing events caused by human motion from video sequences in an office environment. The proposed approach analyzes human motions using Motion History Image (MHI) sequences, and is invariant to body shapes. types or colors of clothes and positions of target objects. The proposed method has two advantages; one is thant the proposed method is less sensitive to illumination changes comparing with the method using color information of objects of interest, and the other is scale invariance comparing with the method using a prior knowledge like appearances or shapes of objects of interest. Combined with edge detection, geometrical characteristics of the human shape in the MHI sequences are considered as the features. An advantage of the proposed method is that the event detection framework is easy to extend by inserting the descriptions of events. In addition, the proposed method is the core technology for event detection systems based on context-aware computing as well as surveillance systems based on computer vision techniques.

A Review of Assistive Listening Device and Digital Wireless Technology for Hearing Instruments

  • Kim, Jin Sook;Kim, Chun Hyeok
    • Korean Journal of Audiology
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    • v.18 no.3
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    • pp.105-111
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    • 2014
  • Assistive listening devices (ALDs) refer to various types of amplification equipment designed to improve the communication of individuals with hard of hearing to enhance the accessibility to speech signal when individual hearing instruments are not sufficient. There are many types of ALDs to overcome a triangle of speech to noise ratio (SNR) problems, noise, distance, and reverberation. ALDs vary in their internal electronic mechanisms ranging from simple hard-wire microphone-amplifier units to more sophisticated broadcasting systems. They usually use microphones to capture an audio source and broadcast it wirelessly over a frequency modulation (FM), infra-red, induction loop, or other transmission techniques. The seven types of ALDs are introduced including hardwire devices, FM sound system, infra-red sound system, induction loop system, telephone listening devices, television, and alert/alarm system. Further development of digital wireless technology in hearing instruments will make possible direct communication with ALDs without any accessories in the near future. There are two technology solutions for digital wireless hearing instruments improving SNR and convenience. One is near-field magnetic induction combined with Bluetooth radio frequency (RF) transmission or proprietary RF transmission and the other is proprietary RF transmission alone. Recently launched digital wireless hearing aid applying this new technology can communicate from the hearing instrument to personal computer, phones, Wi-Fi, alert systems, and ALDs via iPhone, iPad, and iPod. However, it comes with its own iOS application offering a range of features but there is no option for Android users as of this moment.

Nonlinear finite element modeling of the self-centering steel moment connection with cushion flexural damper

  • Ali Nazeri;Reza Vahdani;Mohammad Ali Kafi
    • Structural Engineering and Mechanics
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    • v.87 no.2
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    • pp.151-164
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    • 2023
  • The latest earthquake's costly repairs and economic disruption were brought on by excessive residual drift. Self-centering systems are one of the most efficient ways in the current generation of seismic resistance system to get rid of and reduce residual drift. The mechanics and behavior of the self-centering system in response to seismic forces were impacted by a number of important factors. The amount of post-tensioning (PT) force, which is often employed for the standing posture after an earthquake, is the first important component. The energy dissipater element is another one that has a significant impact on how the self-centering system behaves. Using the damper as a replaceable and affordable tool and fuse in self-centering frames has been recommended to boost energy absorption and dampening of structural systems during earthquakes. In this research, the self-centering steel moment frame connections are equipped with cushion flexural dampers (CFDs) as an energy dissipator system to increase energy absorption, post-yielding stiffness, and ease replacement after an earthquake. Also, it has been carefully considered how to reduce permanent deformations in the self-centering steel moment frames exposed to seismic loads while maintaining adequate stiffness, strength, and ductility. After confirming the FE model's findings with an earlier experimental PT connection, the behavior of the self-centering connection using CFD has been surveyed in this study. The FE modeling takes into account strands preloading as well as geometric and material nonlinearities. In addition to contact and sliding phenomena, gap opening and closing actions are included in the models. According to the findings, self-centering moment-resisting frames (SF-MRF) combined with CFD enhance post-yielding stiffness and energy absorption with the least amount of permeant deformation in a certain CFD thickness. The obtained findings demonstrate that the effective energy dissipation ratio (β), is increased to 0.25% while also lowering the residual drift to less than 0.5%. Also, this enhancement in the self-centering connection with CFD's seismic performance was attained with a respectable moment capacity to beam plastic moment capacity ratio.

Dialogue System for User Customized Lecture Recommendation (사용자 맞춤형 강의 추천을 위한 대화 시스템 연구)

  • Choi, Yerin;Yeen, Yeen-heui;Kim, Dong-Geun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2022.10a
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    • pp.84-86
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    • 2022
  • Task-oriented chatbots prevail in various filed with the artificial intelligent dialogue system. The need for chatbots in customer services is growing, especially in education businesses given that there are many user inquiries and consultation requests. However, current dialogue systems only function as simple reactions or predetermined and frequently used actions. Meanwhile, the research about customized recommendation systems through artificial intelligence is very active with a wide variety of educational content. Although a dialogue system and a recommendation system is a core element in this domain, it has a limitation in that it is being conducted separately. Therefore, we present a study on a recommendation system that can recommend user-customized lectures combined with a dialogue system. With this combination, our system can respond to additional functions beyond these limitations. Through our research, we expect that work efficiency and user satisfaction will be improved by applying chatbots in education domains that are becoming more diversified and personalized.

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The Effect of Interaction between Project Manager's Capabilities and Organizational Structure on Corporate Performance (프로젝트 관리자의 역량과 조직형태의 상호작용이 기업성과에 미치는 영향)

  • Seong-Il Lee;Seung-Chul Kim;Minjeong Oh;Sung-Yong Choi
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.47 no.3
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    • pp.202-216
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    • 2024
  • In today's rapidly changing business environment, rapid decision making and effective project management are essential for business growth. This study examines how project manager competencies and organizational structures affect business performance. Successful project execution depends on the strategic use of project managers' skills and organizational resources to maximize performance. An empirical study was conducted with 475 participants from the construction and engineering sectors. The applied analyses included multiple regression analysis and two-way ANOVA to assess how project manager competencies and organizational types affect business performance. The results of the study show that project manager competencies significantly improve business performance, especially when combined with appropriate organizational types. Effective use of organizational frameworks leads to better financial results, increased market competitiveness, and greater innovation. The results of the study are as follows: First, project manager competencies were found to have a significant positive effect on business performance. Second, the use of functional, project, and matrix organizations had a significant positive effect on business performance. This suggests that aligning organizational structures with business objectives is important for achieving optimal performance. Overall, this study provides valuable insights into the academic literature and practical applications of project management and organizational research. In addition, if we can select organizational members based on the learning effects of previous projects when operating new projects in the future, it will help reduce risks. Ultimately, it will improve the project manager's competency level, promote the individual abilities and knowledge sharing of team members, and provide opportunities for the company to build efficient new systems. This will be evaluated as a valuable study in terms of academic and practical productivity.

Exploring Time Series Data Information Extraction and Regression using DTW based kNN (DTW 거리 기반 kNN을 활용한 시계열 데이터 정보 추출 및 회귀 예측)

  • Hyeonjun Yang;Chaeguk Lim;Woohyuk Jung;Jihwan Woo
    • Information Systems Review
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    • v.26 no.2
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    • pp.83-93
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    • 2024
  • This study proposes a preprocessing methodology based on Dynamic Time Warping (DTW) and k-Nearest Neighbors (kNN) to effectively represent time series data for predicting the completion quality of electroplating baths. The proposed DTW-based kNN preprocessing approach was applied to various regression models and compared. The results demonstrated a performance improvement of up to 43% in maximum RMSE and 24% in MAE compared to traditional decision tree models. Notably, when integrated with neural network-based regression models, the performance improvements were pronounced. The combined structure of the proposed preprocessing method and regression models appears suitable for situations with long time series data and limited data samples, reducing the risk of overfitting and enabling reasonable predictions even with scarce data. However, as the number of data samples increases, the computational load of the DTW and kNN algorithms also increases, indicating a need for future research to improve computational efficiency.

Exploring the Effect of Gamification and Privacy Concerns upon Behavioural Intention to Use Fitness Apps (게임화 및 개인정보 염려가 피트니스 앱 사용의도에 미치는 영향)

  • Melisa Gunhan;Hyojung Song;Taeha Kim
    • Information Systems Review
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    • v.26 no.2
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    • pp.185-203
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    • 2024
  • This study empirically explores the influence of gamification elements and privacy concerns on users' intention to use fitness apps, based on the technology acceptance model (TAM). This research classifies gamification in fitness apps into three categories: achievement-related elements, social-related elements, and immersion-related elements. Although previous research investigated the gamification of fitness apps, few studies combined the impact of gamification with privacy concerns. Considering the significant amount of sensitive personal data collected by fitness apps, we recognize the importance of data privacy and aim to address this gap in research. To achieve this goal, we collected and analyzed data from 187 Korean fitness app users through an online questionnaire. The results confirm the highly significant influence of perceived ease of use, perceived usefulness, and achievement-related gamification elements. Social-related gamification elements, immersion-related gamification elements, and privacy concerns however show insignificant results for the intention to use fitness apps in the Korean market. Location and time limit the generalizability of this study; however, the findings of this study nonetheless offer valuable insights for practitioners and developers to enhance the design and development of their applications.

How to improve the accuracy of recommendation systems: Combining ratings and review texts sentiment scores (평점과 리뷰 텍스트 감성분석을 결합한 추천시스템 향상 방안 연구)

  • Hyun, Jiyeon;Ryu, Sangyi;Lee, Sang-Yong Tom
    • Journal of Intelligence and Information Systems
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    • v.25 no.1
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    • pp.219-239
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    • 2019
  • As the importance of providing customized services to individuals becomes important, researches on personalized recommendation systems are constantly being carried out. Collaborative filtering is one of the most popular systems in academia and industry. However, there exists limitation in a sense that recommendations were mostly based on quantitative information such as users' ratings, which made the accuracy be lowered. To solve these problems, many studies have been actively attempted to improve the performance of the recommendation system by using other information besides the quantitative information. Good examples are the usages of the sentiment analysis on customer review text data. Nevertheless, the existing research has not directly combined the results of the sentiment analysis and quantitative rating scores in the recommendation system. Therefore, this study aims to reflect the sentiments shown in the reviews into the rating scores. In other words, we propose a new algorithm that can directly convert the user 's own review into the empirically quantitative information and reflect it directly to the recommendation system. To do this, we needed to quantify users' reviews, which were originally qualitative information. In this study, sentiment score was calculated through sentiment analysis technique of text mining. The data was targeted for movie review. Based on the data, a domain specific sentiment dictionary is constructed for the movie reviews. Regression analysis was used as a method to construct sentiment dictionary. Each positive / negative dictionary was constructed using Lasso regression, Ridge regression, and ElasticNet methods. Based on this constructed sentiment dictionary, the accuracy was verified through confusion matrix. The accuracy of the Lasso based dictionary was 70%, the accuracy of the Ridge based dictionary was 79%, and that of the ElasticNet (${\alpha}=0.3$) was 83%. Therefore, in this study, the sentiment score of the review is calculated based on the dictionary of the ElasticNet method. It was combined with a rating to create a new rating. In this paper, we show that the collaborative filtering that reflects sentiment scores of user review is superior to the traditional method that only considers the existing rating. In order to show that the proposed algorithm is based on memory-based user collaboration filtering, item-based collaborative filtering and model based matrix factorization SVD, and SVD ++. Based on the above algorithm, the mean absolute error (MAE) and the root mean square error (RMSE) are calculated to evaluate the recommendation system with a score that combines sentiment scores with a system that only considers scores. When the evaluation index was MAE, it was improved by 0.059 for UBCF, 0.0862 for IBCF, 0.1012 for SVD and 0.188 for SVD ++. When the evaluation index is RMSE, UBCF is 0.0431, IBCF is 0.0882, SVD is 0.1103, and SVD ++ is 0.1756. As a result, it can be seen that the prediction performance of the evaluation point reflecting the sentiment score proposed in this paper is superior to that of the conventional evaluation method. In other words, in this paper, it is confirmed that the collaborative filtering that reflects the sentiment score of the user review shows superior accuracy as compared with the conventional type of collaborative filtering that only considers the quantitative score. We then attempted paired t-test validation to ensure that the proposed model was a better approach and concluded that the proposed model is better. In this study, to overcome limitations of previous researches that judge user's sentiment only by quantitative rating score, the review was numerically calculated and a user's opinion was more refined and considered into the recommendation system to improve the accuracy. The findings of this study have managerial implications to recommendation system developers who need to consider both quantitative information and qualitative information it is expect. The way of constructing the combined system in this paper might be directly used by the developers.

Optimization of the Community Energy Supply System for D-Cube City, Multi Purpose Building (복합건물(D-Cube City) 지역에너지 공급체계 최적화)

  • Lee, Tae-Won;Kim, Yong-Ki;Lee, Kun-Woo;Lee, Ki-Bong;Cho, Dong-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.6
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    • pp.669-674
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    • 2012
  • D-Cube City is a recently completed multi purpose building consisting of four types of facilities; offices, a department store, a hotel, and congregation spaces. A community energy supply system(CES) has been installed to supply this building with electricity, steam, heat, and cold water. The BEMS, building energy management system, is currently being designed to reduce building energy consumption through the efficient operation of the various pieces of building service equipment. In this study the optimal methods for operating the CES of D-Cube City were considered. This system includes three combined heat and power systems, seven steam boilers, two hot water boilers, two absorption chillers, and four turbo chillers, and various other pieces of equipment. In result, the optimal methods of operating the CES for various energy demand levels were obtained along with the seasonal effects on the economic efficiency of the operation. The effect of the amount of energy demanded by the various facility areas on the total energy consumption was also analyzed.