• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.4 s.175
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• pp.811-823
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• 2000

In design and manufacturing airframe structures which are composed of a lot of sub-assemblies and large complex profile shapes it is difficult to reduce so called hardware variations. Accordingly cost increasing factors for manufacturing airframe parts are much more than other machine parts because of the variability of fabricated details and assemlies. To improve cost and quality, accurate assembly methods and DPD techniques are proposed in this paper which are based upon using CAD/CAM techniques, the concept of KC's and the coordinated datum and index throughout the design, tooling, manufacturing and inspection. The proposed methods are applied to produce fuselage frame assemblies and related engineering aspects are described regarding the design of parts and tools in the context of concurrent digital definition. First articles and consequent mass production of frame assemblies shows a great improvement of the process capability ratio from 0.7 by the past processes to 1.0 by the proposed methods in addition to the cost reduction due to the less number of tools, reduced total assembly times and the space compaction needed by massive inventory. The need to achieve better Cpk, however, and future studies to be investigated will be addressed briefly.

• The Transactions of the Korea Information Processing Society
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• v.3 no.4
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• pp.720-732
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• 1996

Spatial match retrieval methods for iconic image databases recognize an image document as several icon symbols. Therefore the iconic symbols are used as primary keys to index the image document. When a user requires content-based retrieval ofimages, a spatial match retrieval method converts a query image into iconic symbols and then retrieves relevant images by accessing stored images. In order to support content-based image retrieval efficiently, we, in this paper, propose spatial match retrieval methods using signatures for iconic image databases. For this, we design new index representations of two-dimensional iconic images and explain implemented system.. In addition, we compare the conventional 9-DLT and our two-dimensional image retrieval method in terms of retrieval precision and recall ratio. We show that our method is more efficient than the conventional method.

• Journal of the Korea Computer Industry Society
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• v.2 no.4
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• pp.507-520
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• 2001

In this paper, a hybrid algorithm for well detecting both abrupt and gradual scene changes is proposed. This algorithm examines only the candidate intervals for speedup using the binary tree method and skips the intervals that are not candidate. For accuracy, the temporal difference of variance is used to detect the gradual scene changes while the temporal difference of histogram is used to detect the abrupt scene changes. Experimental results show that the proposed hybrid algorithm using the binary tree method works up about 10 times faster that the sequential method and is effective in detecting abrupt scene change and gradual transitions including dissolving and fading.

• The KIPS Transactions:PartD
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• v.13D no.1 s.104
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• pp.29-36
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• 2006

In this paper, we present a leaf image retrieval system that represents and retrieves leaf images based on their shape. For more effective representation of leaf images, we improved an existing MPP algorithm. Also, in order to reduce the response time, we proposed a new dynamic matching algorithm at basically revises the Nearest Neighbor search. The system provides users with an interface for uploading query images or tools to generate queries based on shape features and retrieves images based on their similarity. For convenience, users are allowed to easily query images by sketching leaf shape or leaf arrangement on the web. In the experiment, we constructed an image database of Korean native plants and measured the system performance by counting the number of similar images retrieved for queries.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.737-748
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• 2003

With the popularity of digital music contents, querying and retrieving music contents efficiently from database has become essential. In this paper, we propose a Fast Melody Finder (FMF) that can retrieve melodies fast and efficiently from music database using frequently queried tunes. This scheme is based on the observation that users have a tendency to memorize and query a small number of melody segments, and indexing such segments enables fast retrieval. To handle those tunes, FMF transcribes all the acoustic and common music notational inputs into a specific string such as UDR and LSR. We have implemented a prototype system and showed on its performance through various experiments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.2
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• pp.396-406
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• 2009

In extension to our previous study, we develop metadata that specify elements' structural orders, to increase the efficiency level of XML document's retrieval process. Then, we proposed a structure-based indexing model. We expect the model to generate a more efficient retrieval process of horizontally and vertically related elements. To evaluate the model's performance level, we developed an experimental prototype and conducted an experiment on an XML corpus. On average, descendant, ancestor and sibling retrievals were approximately twelve percent faster than the ETID model. And retrievals specifying structural orders of particular element types were approximately twenty-five percent faster than the ETID model. In conclusion, metadata, such as Etype, Asso and Lsso, may make a meaningful contribution to retrieval processes that specify elements' order.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.277-280
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• 2009

IPTV, 블루레이 디스크, DMB 등과 같은 멀티미디어 서비스에서 H.264/AVC 비디오 표준기술을 채택하고 있다. 따라서 H.264/AVC 비트스트림을 고속으로 인덱싱하기 위한 썸네일 기술이 요구 된다. 그러나 H.264/AVC는 기존 표준기술과는 다르게 인트라 모드에서도 예측방법을 이용하기 때문에 새로운 썸네일 추출방법이 요구되어 최근에 H.264/AVC 비트스트림 상에서 썸네일을 추출하는 방법이 제안되었다. 그러나 이 방법에서는 인트라 $16{\times}16$ 모드와 연관된 블록에서 심각한 화질의 저하가 발생하며, QP 값이 커질수록 그 증상이 더 심해지는 문제점이 있다. 그리고 공간주파수 영역에서 처리하기 때문에 예측 모드에 따라 연산오류가 발생하여 이 오류가 파급되는 문제가 있다. 따라서 본 논문에서는 공간주파수 영역에서 H.264/AVC 썸네일을 추출할 때 인트라 $16{\times}16$ 예측 모드에서도 오류가 발생하지 않도록 하는 방법과 공간주파수 영역에서 발생하는 연산 오류를 보상하는 방법을 제안한다. 그리고 제안한 방법을 다양한 시험 비디오 시퀀스에 적용하여 이전 썸네일 추출 방법과 비교하여 프레임에 따라 최대 PSNR 약 4dB 증가 및 주관적 화질을 향상시켰다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.7
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• pp.693-701
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• 2010

In this paper, it is proposed that an attitude and position estimation algorithm based on a stereo camera system for a helmet tracker. Stereo camera system consists of two CCD camera, a helmet, infrared LEDs and a frame grabber. Fifteen infrared LEDs are feature points which are used to determine the attitude and position of the helmet. These features are arranged in triangle pattern with different distance on the helmet. Vision-based the attitude and position algorithm consists of feature segmentation, projective reconstruction, model indexing and attitude estimation. In this paper, the attitude estimation algorithm using UQ (Unit Quaternion) is proposed. The UQ guarantee that the rotation matrix is a unitary matrix. The performance of presented algorithm is verified by simulation and experiment.

• Journal of Korea Multimedia Society
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• v.8 no.1
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• pp.1-8
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• 2005

Similar melody searching is an operation that finds such melodies similar to a given query melody from a music database. In this paper, we address the development of a system that detects plagiarism based on the similar melody searching. We first Propose a novel similarity model that supports alignment as well as shifting. Also, we suggest a method for indexing the features extracted from each melody, and a method for processing plagiarism detection by using the index. By our plagiarism detection system composers can easily searches for such melodies that are similar to their ones from music databases. Through performance evaluation via a series of experiments, we show the effectiveness of our approach. The results reveal that our approach outperforms the sequential-scan-based one in speed up to around 31 times.

• Journal of KIISE:Databases
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• v.31 no.4
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• pp.341-351
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• 2004

With the popularity of digital audio contents, querying and retrieving audio contents efficiently from database has become essential. In this paper, we propose a new index scheme for retrieving audio contents efficiently using audio portions that have been queried frequently. This scheme is based on the observation that users have a tendency to memorize and query a small number of audio portions. Detecting and indexing such portions enables fast retrieval and shows better performance than sequential search-based audio retrieval. Moreover, this scheme is independent of underlying retrieval system, which means this scheme can work together with any other audio retrieval system. We have implemented a prototype system and showed its performance gain through experiments.