• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.3
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• pp.243-251
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• 2016

LiDAR data processing steps include noise removal, filtering, classification, segmentation, shape recognition, modeling, and quality assessment. This paper focuses on modeling and accuracy evaluation of 3D objects with curved surfaces. The appropriate modeling functions were determined by analyzing surface patch shape. Existing methods for modeling curved surface features require linearization, initial approximation, and iteration of the non-linear functions. However, proposed method could directly estimate the unknown parameters of the modeling functions. The results demonstrate feasibility of the proposed method. The proposed method was applied to the simulated and real building data of hemi-spherical and semi-cylindrical surfaces. The parameters and accuracy of the modeling functions were estimated. It is expected that the proposed method would contribute to automatic modeling of various objects.

• Journal of KIISE:Information Networking
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• v.29 no.6
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• pp.663-673
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• 2002

Server-side anti-viruses are useful to protect their domains, because they can detect malicious codes at the gateway of their domains. In prevailing local network, all clients cannot be perfectly controlled by domain administrators, so server-side inspection, for example in e-mail server, is used as an efficient technique of detecting mobile malicious codes. However, current server-side anti-virus systems perform only signature-based detection for known malicious codes, simple filtering, and file name modification. One of the main reasons that they don't have detection features, for unknown malicious codes, is that activity monitoring technique is unavailable for server machines. In this paper, we propose a detection technique that is executed at the server, but it can monitor activities at the clients without any anti-virus features. we describe its implementation.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.385-390
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• 2006

모바일 환경이 언제, 어디서든지 원하는 서비스나 콘텐츠에 접근할 수 있다는 장점에도 불구하고, 모바일 단말기는 여러 가지 취약한 단점들을 가지고 있다. DMB, 인터넷, 모바일 등에 대한 콘텐츠 또는 정보의 양이 거대하게 증가하면서 사용자는 때때로 자신이 원하는 콘텐츠를 찾는데 어려움을 겪게 되며, 많은 시간을 소비하게 된다. 발전하는 모바일 환경 및 단말기의 장점을 최대한 이용할 뿐만 아니라 모바일 단말기가 가지는 제약 사항들의 한계를 극복하여 사용자가 원하는 정보 및 콘텐츠를 언제 어디서나 빠른 시간에 이용할 수 있는 모바일 환경에 적합한 추천시스템의 필요성은 증가하고 있다. 본 논문에서는 기존의 서버 중심의 추천시스템을 개선하여 클라이언트와 서버간의 데이터 교환을 통하여 추천 정확도를 높일 수 있는 추천시스템 구조를 제안한다. 제안하는 시스템은 사용자의 히스토리를 이용하며, 클라이언트에서는 모바일 단말기 사용자만의 히스토리를 이용한 추천 알고리즘을 적용하였고, 서버에서는 협업 필터링을 통해 다른 사용자의 히스토리를 이용한 추천 알고리즘을 적용하였다. 실험 결과는 서버 중심의 추천시스템 보다 더 높은 정확도를 제공할 수 있다는 것을 보여준다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.4
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• pp.345-352
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• 2020

To preserve and restore tidal flats and prevent safety accidents, it is necessary to construct tidal flat topographic information including the exact location and shape of tidal creeks. In the tidal flats where the field surveying is difficult to apply, airborne LiDAR surveying can provide accurate terrain data for a wide area. On the other hand, we can economically obtain relatively high-resolution data from UAV (Unmanned Aerial Vehicle) surveying. In this study, we proposed the methodology to generate high-resolution topographic information of tidal flats effectively by integrating airborne LiDAR and UAV point clouds. For the purpose, automatic ICP (Iterative Closest Points) registration between two different datasets was conducted and tidal creeks were extracted by applying CSF (Cloth Simulation Filtering) algorithm. Then, we integrated high-density UAV data for tidal creeks and airborne LiDAR data for flat grounds. DEM (Digital Elevation Model) and tidal flat area and depth were generated from the integrated data to construct high-resolution topographic information for large-scale tidal flat map creation. As a result, UAV data was registered without GCP (Ground Control Point), and integrated data including detailed topographic information of tidal creeks with a relatively small data size was generated.

• Korean Journal of Remote Sensing
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• v.39 no.5_4
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• pp.1145-1153
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• 2023

Urban trees play an important role in absorbing carbon dioxide from the atmosphere, improving air quality, mitigating the urban heat island effect, and providing ecosystem services. To effectively manage and conserve urban trees, accurate spatial information on their location, condition, species, and population is needed. In this study, we propose an algorithm that uses a high-resolution urban tree cover map constructed from deep learning approach to separate trees from the urban land surface and accurately detect tree locations through local maximum filtering. Instead of using a uniform filter size, we improved the tree detection performance by selecting the appropriate filter size according to the tree height in consideration of various urban growth environments. The research output, the location and height of individual trees in human settlement over Suwon, will serve as a basis for sustainable management of urban ecosystems and carbon reduction measures.

• Spatial Information Research
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• v.22 no.1
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• pp.75-84
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• 2014

Power lines are one of the main obstacles causing an aircraft crash and thus their realtime detection is significantly important during flight. To avoid such flight obstacles, the use of LIDAR has been recently increasing thanks to its advantages that it is less sensitive to weather conditions and can operate in day and night. In this study, we suggest a fast method to detect power lines from LIDAR data for flight obstacle avoidance. The proposed method first extracts non-ground points by eliminating the points reflected from ground surfaces using a filtering process. Second, we calculate the eigenvalues for the covariance matrix from the coordinates of the generated non-ground points and obtain the ratio of eigenvalues. Based on the ratio of eigenvalues, we can classify the points on a linear structure. Finally, among them, we select the points forming horizontally long straight as power-line points. To verify the algorithm, we used both real and simulated data as the input data. From the experimental results, it is shown that the average detection rate and time are 80% and 0.2 second, respectively. If we would improve the method based on the experiment results from the various flight scenario, it will be effectively utilized for a flight obstacle avoidance system.

• Convergence Security Journal
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• v.6 no.2
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• pp.21-29
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• 2006

Recently, illegal manipulation and forgery threats on computer softwares are increasing. Specially, forge the code of program and disrupt normal operation using a malicious loader program against the Internet application client. In this paper, we first analyze and generate signatures of malicious loader detection. And, we propose a method to secure the application client based on profiling which can detect and filter out abnormal malicious loader requests.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.11a
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• pp.697-700
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• 2006

오늘날 인터넷 광범위한 보급은 무선 이동 통신 기술로 급발전하고 무선 단말기의 보급과 폭발적인 증가로 인해 m-commerce가 차세대 상거래의 형태가 될 것으로 예상된다. 현재 m-commerce의 컨텐츠는 m-commerce와는 호환되지 않으며, 질적으로나 양적으로 그 내용이 매우 빈약하다. 따라서 m-commerce의 상품정보 컨텐츠를 m-commerce를 위해서 활용하는 방안이 요구되는데, 여기에는 무선 단말기의 제한된 처리 능력이 고려되어야 한다. 논문에서는 먼저 인터넷 상의 방대한 상품정보를 사용자의 선호도에 기반하여 효과적으로 여과시켜서 사용자가 관심있는 정보만을 간추려서 제공할 수 있는 시스템을 설계하고 구현한다. 다음에 구현된 시스템을 인터넷 쇼핑몰에 대해서 적용한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.3
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• pp.193-198
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• 2023

We study a learner-customized lecture recommendation project using deep learning. Recommendation systems can be easily found on the web and apps, and examples using this feature include recommending feature videos by clicking users and advertising items in areas of interest to users on SNS. In this study, the sentence similarity Word2Vec was mainly used to filter twice, and the course was recommended through the Surprise library. With this system, it provides users with the desired classification of course data conveniently and conveniently. Surprise Library is a Python scikit-learn-based library that is conveniently used in recommendation systems. By analyzing the data, the system is implemented at a high speed, and deeper learning is used to implement more precise results through course steps. When a user enters a keyword of interest, similarity between the keyword and the course title is executed, and similarity with the extracted video data and voice text is executed, and the highest ranking video data is recommended through the Surprise Library.

• Journal of the Institute of Convergence Signal Processing
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• v.16 no.4
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• pp.175-181
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• 2015

In this paper, we propose a design method for a digital filter using software in order to analyze the radio astronomy observation data. Recently the analysis method for radio astronomy observing system is transferring from hardware to software by developing of state-of-the-art of computer system. The existing hardware system is not able to easily change the specification because it is implemented to meet special requirements and it takes a high cost and time. In case of software, however, it has an advantage to implement with small cost if open software is used, and flexibly changes to satisfy the desired specification. But, in order to analyze the massive data like radio astronomy with software, the good performance system is needed for computer. Therefore, this paper proposes a digital filter design method using software with the same performance as that of digital filter implemented with hardware in observation system which is operated by the KVN(Korean VLBI Network). To design a digital filter, the proposed method is performed with standard C language and the simulation is conducted with GNU(GNU's Not Unix) Octave and investigated to show its effectiveness. In addition, for the high speed operation of the designed digital filter, the SSE(Streaming SIMD Extensions) library is adopted for available parallel operation. By the proposed digital filter, the digital filtering is performed for the wide band observation data in the KVN observation mode, the filtering result of narrow band observation has no ripple inside of stop band, and confirmed the effectiveness of the proposed method.