• Title/Summary/Keyword: Online detection

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Object Tracking Based on Exactly Reweighted Online Total-Error-Rate Minimization (정확히 재가중되는 온라인 전체 에러율 최소화 기반의 객체 추적)

  • JANG, Se-In;PARK, Choong-Shik
    • Journal of Intelligence and Information Systems
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    • v.25 no.4
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    • pp.53-65
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    • 2019
  • Object tracking is one of important steps to achieve video-based surveillance systems. Object tracking is considered as an essential task similar to object detection and recognition. In order to perform object tracking, various machine learning methods (e.g., least-squares, perceptron and support vector machine) can be applied for different designs of tracking systems. In general, generative methods (e.g., principal component analysis) were utilized due to its simplicity and effectiveness. However, the generative methods were only focused on modeling the target object. Due to this limitation, discriminative methods (e.g., binary classification) were adopted to distinguish the target object and the background. Among the machine learning methods for binary classification, total error rate minimization can be used as one of successful machine learning methods for binary classification. The total error rate minimization can achieve a global minimum due to a quadratic approximation to a step function while other methods (e.g., support vector machine) seek local minima using nonlinear functions (e.g., hinge loss function). Due to this quadratic approximation, the total error rate minimization could obtain appropriate properties in solving optimization problems for binary classification. However, this total error rate minimization was based on a batch mode setting. The batch mode setting can be limited to several applications under offline learning. Due to limited computing resources, offline learning could not handle large scale data sets. Compared to offline learning, online learning can update its solution without storing all training samples in learning process. Due to increment of large scale data sets, online learning becomes one of essential properties for various applications. Since object tracking needs to handle data samples in real time, online learning based total error rate minimization methods are necessary to efficiently address object tracking problems. Due to the need of the online learning, an online learning based total error rate minimization method was developed. However, an approximately reweighted technique was developed. Although the approximation technique is utilized, this online version of the total error rate minimization could achieve good performances in biometric applications. However, this method is assumed that the total error rate minimization can be asymptotically achieved when only the number of training samples is infinite. Although there is the assumption to achieve the total error rate minimization, the approximation issue can continuously accumulate learning errors according to increment of training samples. Due to this reason, the approximated online learning solution can then lead a wrong solution. The wrong solution can make significant errors when it is applied to surveillance systems. In this paper, we propose an exactly reweighted technique to recursively update the solution of the total error rate minimization in online learning manner. Compared to the approximately reweighted online total error rate minimization, an exactly reweighted online total error rate minimization is achieved. The proposed exact online learning method based on the total error rate minimization is then applied to object tracking problems. In our object tracking system, particle filtering is adopted. In particle filtering, our observation model is consisted of both generative and discriminative methods to leverage the advantages between generative and discriminative properties. In our experiments, our proposed object tracking system achieves promising performances on 8 public video sequences over competing object tracking systems. The paired t-test is also reported to evaluate its quality of the results. Our proposed online learning method can be extended under the deep learning architecture which can cover the shallow and deep networks. Moreover, online learning methods, that need the exact reweighting process, can use our proposed reweighting technique. In addition to object tracking, the proposed online learning method can be easily applied to object detection and recognition. Therefore, our proposed methods can contribute to online learning community and object tracking, detection and recognition communities.

Research on online game bot guild detection method (온라인 게임 봇 길드 탐지 방안 연구)

  • Kim, Harang;Kim, Huy Kang
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.25 no.5
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    • pp.1115-1122
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    • 2015
  • In recent years, the use of game bots by illegal programs has been expanded from individual to group scale; this brings about serious problems in online game industry. The gold farmers group creates an in-game social community so-called "guild" to obtain a large amount of game money and manage game bots efficiently. Although game developers detect game bots by detection algorithms, the algorithms can detect only part of the gold farmers group. In this paper, we propose a detection method for the gold farmers group on a basis of normal and bot guilds characteristic analysis. In order to differentiate normal and bots guild, we analyze transaction patterns for individuals, auction house and chatting. With the analyzed results, we can detect game bot guilds. We demonstrate the feasibility of the proposed methods with real datasets from one of the popular online games named AION in Korea.

Cable anomaly detection driven by spatiotemporal correlation dissimilarity measurements of bridge grouped cable forces

  • Dong-Hui, Yang;Hai-Lun, Gu;Ting-Hua, Yi;Zhan-Jun, Wu
    • Smart Structures and Systems
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    • v.30 no.6
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    • pp.661-671
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    • 2022
  • Stayed cables are the key components for transmitting loads in cable-stayed bridges. Therefore, it is very important to evaluate the cable force condition to ensure bridge safety. An online condition assessment and anomaly localization method is proposed for cables based on the spatiotemporal correlation of grouped cable forces. First, an anomaly sensitive feature index is obtained based on the distribution characteristics of grouped cable forces. Second, an adaptive anomaly detection method based on the k-nearest neighbor rule is used to perform dissimilarity measurements on the extracted feature index, and such a method can effectively remove the interference of environment factors and vehicle loads on online condition assessment of the grouped cable forces. Furthermore, an online anomaly isolation and localization method for stay cables is established, and the complete decomposition contributions method is used to decompose the feature matrix of the grouped cable forces and build an anomaly isolation index. Finally, case studies were carried out to validate the proposed method using an in-service cable-stayed bridge equipped with a structural health monitoring system. The results show that the proposed approach is sensitive to the abnormal distribution of grouped cable forces and is robust to the influence of interference factors. In addition, the proposed approach can also localize the cables with abnormal cable forces online, which can be successfully applied to the field monitoring of cables for cable-stayed bridges.

A Research on the Use of DID Using a Private Blockchain (프라이빗 블록체인을 사용한 DID 활용 연구)

  • Park, Jong-Gyu;Kwon, Seong-Geun;Kwon, Ki-Ryong;Lee, Suk-Hwan
    • Journal of Korea Multimedia Society
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    • v.24 no.6
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    • pp.760-767
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    • 2021
  • The identity verification is one of the most important technologies in online services. Many services in society are provided online, and the service is provided after confirming the user's identity. Users can do a lot of things online, but they also have side effects. Online digital information is easily manipulated and it is difficult to verify its authenticity, causing social confusion. Accordingly, there has been a movement for individuals to directly manage their identity information using DID. In this paper, we propose a system that can authenticate identity by directly adding own personal information and issuing an identifier using DID technology based on a private blockchain. Then, to verify the proposed system, the scenario is executed and verified.

A research on improving client based detection feature by using server log analysis in FPS games (FPS 게임 서버 로그 분석을 통한 클라이언트 단 치팅 탐지 기능 개선에 관한 연구)

  • Kim, Seon Min;Kim, Huy Kang
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.25 no.6
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    • pp.1465-1475
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    • 2015
  • Cheating detection models in the online games can be divided into two parts. The one is on client based model, which is designed to detect malicious programs not to be run while playing the games. The other one is server based model, which distinguishes the difference between benign users and cheaters by the server log analysis. The client based model provides various features to prevent games from cheating, For instance, Anti-reversing, memory manipulation and so on. However, being deployed and operated on the client side is a huge weak point as cheaters can analyze and bypass the detection features. That Is why the server based model is an emerging way to detect cheating users in online games. But the simple log data such as FPS's one can be hard to find validate difference between two of them. In this paper, In order to compensate for the disadvantages of the two detection model above, We use the existing game security solution log as well as the server one to bring high performance as well as detection ratio compared to the existing detection models in the market.

A Study of Player Changed-pattern Model for Game Bots Detection in MMORPG (MMORPG에서 게임 봇 프로그램 탐지를 위한 플레이어 패턴 변화 모델에 관한 연구)

  • Yoon, Tae-Bok;Lee, Jee-Hyong
    • Journal of Korea Game Society
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    • v.11 no.1
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    • pp.121-129
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    • 2011
  • In an online-game, the various game service victimized cases are generated by the bots program or auto program. Particularly, the abnormal collection of the game money and item loses the inherent fun of a game. It reaches ultimately the definite bad effect to the game life cycle. This paper collects and analyzes the pattern of game behavior change for the bots detection method. By using the game activity changing information of the human and game activity changing information of the bots, the degree of resemblance was measured. It utilized in the bots detection method. In an experiment, by using the served online-game, the model of a user and bots were generated and similarity was distinguished. And the reasonable result was confirmed.

Vision-Based Vehicle Detection and Tracking Using Online Learning (온라인 학습을 이용한 비전 기반의 차량 검출 및 추적)

  • Gil, Sung-Ho;Kim, Gyeong-Hwan
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.1
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    • pp.1-11
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    • 2014
  • In this paper we propose a system for vehicle detection and tracking which has the ability to learn on-line appearance changes of vehicles being tracked. The proposed system uses feature-based tracking method to estimate rapidly and robustly the motion of the newly detected vehicles between consecutive frames. Simultaneously, the system trains an online vehicle detector for the tracked vehicles. If the tracker fails, it is re-initialized by the detection of the online vehicle detector. An improved vehicle appearance model update rule is presented to increase a tracking performance and a speed of the proposed system. Performance of the proposed system is evaluated on the dataset acquired on various driving environment. In particular, the experimental results proved that the performance of the vehicle tracking is significantly improved under bad conditions such as entering a tunnel and passing rain.

Study on Online Monitoring of Dissolved Oxygen, pH and Cell Concentration in E. coli Cultivation Processes Using MABOOMSTM (마이크로플레이트 기반 생물반응기 시스템 (MABOOMSTM)을 이용한 대장균 배양공정에서 용존산소, pH 및 세포농도의 온라인 모니터링 연구)

  • Sohn, Ok-Jae;Rhee, Jong Il
    • KSBB Journal
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    • v.28 no.1
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    • pp.24-30
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    • 2013
  • Dissolved oxygen, pH and cell concentration have been online monitored in cultivation processes with Escherichia coli by using a $MABOOMS^{TM}$ (microplate-based bioreactor with optical online monitoring systems). Fluorescent sensing membranes containing Ru ${(dpp)_3}^{2+}$ or HPTS were prepared with GA sol-gel matrix and coated into a well of a 24-well microplate. Fluorescence intensity was measured and correlated to the dissolved oxygen or pH. Cell concentrations were also online monitored by measuring optical reflectance at 650 nm. A well of a 24-well microplate could also be divided into 4 parts, each of which was coated with fluorescent sensing membranes for the detection of dissolved oxygen or pH. The 24-well microplate coated with fluorescent sensing membranes or a 4-divided sensing membrane. was used to online monitor the dissolved oxygen, pH and cell concentration during E. coli cultivations. The online monitoring results showed the characteristics of cell growth in cultivation processes very well.

Temporal Analysis of Opinion Manipulation Tactics in Online Communities (온라인 공간에서 비정상 정보 유포 기법의 시간에 따른 변화 분석)

  • Lee, Sihyung
    • Journal of Internet Computing and Services
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    • v.21 no.3
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    • pp.29-39
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    • 2020
  • Online communities, such as Internet portal sites and social media, have become popular since they allow users to share opinions and to obtain information anytime, anywhere. Accordingly, an increasing number of opinions are manipulated to the advantage of particular groups or individuals, and these opinions include falsified product reviews and political propaganda. Existing detection systems are built upon the characteristics of manipulated opinions for one particular time period. However, manipulation tactics change over time to evade detection systems and to more efficiently spread information, so detection systems should also evolve according to the changes. We therefore propose a system that helps observe and trace changes in manipulation tactics. This system classifies opinions into clusters that represent different tactics, and changes in these clusters reveal evolving tactics. We evaluated the system with over a million opinions collected during three election campaigns and found various changes in (i) the times when manipulations frequently occur, (ii) the methods to manipulate recommendation counts, and (iii) the use of multiple user IDs. We suggest that the operators of online communities perform regular audits with the proposed system to identify evolutions and to adjust detection systems.

Online Hard Example Mining for Training One-Stage Object Detectors (단-단계 물체 탐지기 학습을 위한 고난도 예들의 온라인 마이닝)

  • Kim, Incheol
    • KIPS Transactions on Software and Data Engineering
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    • v.7 no.5
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    • pp.195-204
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    • 2018
  • In this paper, we propose both a new loss function and an online hard example mining scheme for improving the performance of single-stage object detectors which use deep convolutional neural networks. The proposed loss function and the online hard example mining scheme can not only overcome the problem of imbalance between the number of annotated objects and the number of background examples, but also improve the localization accuracy of each object. Therefore, the loss function and the mining scheme can provide intrinsically fast single-stage detectors with detection performance higher than or similar to that of two-stage detectors. In experiments conducted with the PASCAL VOC 2007 benchmark dataset, we show that the proposed loss function and the online hard example mining scheme can improve the performance of single-stage object detectors.