• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.2
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• pp.143-155
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• 2000

With the increasing needs for the integrated use of topographic and cadastral data in order to build an efficient geo-spatial information system. it is urgently necessary to research into its solution. The intention of this study is to detect error types of data and to propose adjustment methods for solving the problems caused by integrating topographic and cadastral data. For this purpose a primary integrated data model is created to link attribute data(land management system) and graphic data within cadastral information in the first step. In next, a secondary integrated data model based on the improved method is formed to coincide the graphic data of cadastral map with that of topographic map. At the first, because a numerous error types md sources caused by separate management of graphic and attribute data are easily checked, it is possible to suggest an improved method to correct these errors using the primary integrated data model. In addition, the accuracy in position and area with coordinate transformation method based on multi-block adjustment is more efficient than rubber-sheeting method. As a result, the secondary integrated data model could be built by harmonizing cadastral map with topographic map using the improved solution.

• Progress in Medical Physics
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• v.22 no.2
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• pp.67-71
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• 2011

We evaluated the overall setup accuracy for the On-Board Imager (OBI, Varian Medical Systems Inc., Palo Alto, CA, USA), with attention to the laser, the gantry, and operator performance. We let experienced technicians place the marker block on the couch using a lock bar system, with alignment to the isocenter of the laser, every morning. A pair of radiographic images of the marker block was acquired at $0^{\circ}$ and $270^{\circ}$ angles to the kV arm to correct the position using a 2D/2D matching technique. Once the desired match was achieved, the couch was moved remotely to correct the setup error and the parameters were saved. The average for the vertical and the longitudinal displacements were 0.65 mm and 0.66 mm, and 0.01 mm for the lateral displacement. The average for the vertical and longitudinal displacements were statistically significant at the 0.05 level (p value=0.000 for both), while the p value for the lateral direction was 0.829. These results show that the tendencies to displacement in vertical and longitudinal directions occur through systematic error, while systematic error was not found in the lateral displacement. This daily overall evaluation is practical and easy to find the systematic and random errors in the setup system; however, a daily QA for laser and OBI alignment is still needed to minimize the systematic error in aligning patients.

• Journal of Korea Multimedia Society
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• v.5 no.3
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• pp.263-271
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• 2002

In this paper, we propose a new smoothing method for removing moire patterns using analysis of halftone patterns interference. The proposed method can determine a strength of moire patterns by using gray values of pixels and the size of smoothing mask for moire region is adjusted adaptively according to the strength of moire patterns. Therefore it can remove moire patterns effectively and preserve meaningful high frequencies well, such as edges and textures. The proposed method only refer to predefined lookup table to determine the strength of moire patterns, so it is more efficient than a previous work based on FFT of subblock. It could be applied to field of various multimedia applications that deal with color prints.

• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.112-122
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• 2004

In this paper, we propose a mobility estimation model based on inner regions in a cell and a dynamic resource reservation scheme which can control dynamically classes of mobile hosts on the mobile network. The mobility estimation model is modeled based on the reducible Markov chain. And the mobility estimation model provides a new hand off probability and a new remaining time for the dynamic resource reservation scheme. The remaining time is n estimated time that mobile hosts can stay in a cell. The dynamic resource reservation scheme can reserve dynamically a requested resource according to the classes of mobile hosts. This scheme can efficiently improve the connection blocking probability and connection dropping probability.

• Journal of Korea Multimedia Society
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• v.4 no.6
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• pp.500-509
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• 2001

Image compression based on Wavelet gives much better quality than JPEG based on DCT, but suffers from ringing or blurring effects around edges as the compression is increased. In this paper, we proposed enhanced image compression by pre-processing wavelet coefficients. This pre-processing is performed by making a low threshold and enhanced by zerotree scan method when subband's zerotrees are established. It might increase significants coefficient by means of modifying the threshold and reflect on the orientation of subbands. Some experimental results show our method is more efficient than the conventional methods, JPEG. And then the developed coding scheme improves the quality of images and visually shows more pleasing results for most practical images.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.11a
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• pp.98-100
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• 2012

본 논문에서는 좌우 해상도가 서로 다른 융합형 3DTV 시스템에서 합성된 3D 영상의 화질을 개선하는 방법인 조건부 대체 알고리듬에 적용하기 위한 비트율 제어기법을 제안한다. 조건부 대체 알고리듬에서는 쿼드트리 형태의 가변크기 블록마다 좌우 영상간의 양안시차 정보를 활용하되, 이 정보의 전송을 위해서 부가적인 대역폭이 요구되기 때문에 전송 대역폭의 상황에 따라 부가 정보의 양을 효율적으로 조절할 필요가 있다. 이를 위해 비용함수를 정의하고 가중치를 적용하여 최적의 모드를 결정하는 방법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3B
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• pp.529-540
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• 2000

This is paper presents the semantic based rate-control method which is based on very low bit rate video coding standards H.263 plus, applied on very low bit rate applications. Previous rate control methods control the generated bit rates by setting the optimum quantization parameters per macro block unit on frame. But, in this paper, we added the pre-processing algorithm, semantic region recognition and assignment of priority algorithm, to obtain the subjective quality enhancement. This work aims to improve the subjective quality of skin color region or face by using unimportant background region's bit resources.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1147-1154
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• 2011

Auto exposure (AE) in image signal processor (ISP) controls brightness of input image to the proper brightness when it is too dark or bright. But conventional AEs often fail to get proper brightness since AE controls only average brightness of image. Especially in applications that require object recognition, it cannot be solved the problem by AE of ISP. In this paper proposes Histogram Equalization (HE) processes that is the alternative of AE. It also proposes proper method to realize hardware and compensate HE problems conventional by using simple calculation.

• Journal of KIISE:Information Networking
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• v.27 no.3
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• pp.323-330
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• 2000

이동통신망의 발전으로 인해 한정적인 주파수 자원을 효율적으로 사용하여 폭증하는 가입자를 수용하기 위해 셀의 반경은 점점 작아지고 있다. 가입자에게 신규호의 실패보다 더 민감한 핸드오프호가 자주 발생함에 따라 핸드오프호 처리의 중요성이 증대되었다. 따라서, 셀마다 핸드오프호를 위한 예약 채널을 두어 어느 정도 신규호의 블록킹율의 증가를 감수하더라도, 핸드오프호의 강제종료율을 낮추는 방법이 제안되었다. 이러한 예약 채널 할당 기법에서는 예약 채널을 몇 개로 할 것인가가 중요한 문제가 된다. 왜냐하면 예약 채널 수를 과다하게 설정하면 핸드오프가 빈번하지 않은 셀에서는 채널의 낭비를 초래하고, 적게 설정하면 핸드오프가 빈번한 셀은 핸드오프 강제종료율이 높아지게 되기 때문이다. 이러한 문제를 해결하기 위해 본 논문은 신경망 모델 중 다층 퍼셉트론을 이용하여 셀에서 요구되는 최적의 예약율을 구하여 셀의 환경이 변할 때마다 적용할 수 있는 방법을 제안한다. 본 논문에서는 모의 실험을 통해 이동통신 시스템에서의 핸드오프 예약율을 주기적으로 최적화 시킴으로써 핸드오프가 자주 발생하는 셀에서는 핸드오프 강제종료율을 낮추고, 핸드오프가 빈번하지 않은 셀은 채널의 손실을 막아 시스템의 전체적인 효율이 향상됨을 보인다.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.105-108
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• 2004

다단계 보안데이터베이스 시스템에서 기본적인 병행수행 제어 기법들은 비밀채널과 교착상태등과 같은 문제들이 발생하였다. 이에 직렬화 순서를 동적으로 재조정함으로서 해결하려는 방안이 있었지만, 알고리즘의 복잡성으로 인해 오버 헤드와 많은 수행시간이 필요하게 되었고, 이에 따라 많은 양의 시스템 자원과 높은 사양의 시스템을 요구하게 되었다. 또한 이러한 방법은 다중 버전을 사용함으로서 추가적인 관리비용이 높게 되었고, 각각의 트랜잭션이 지연 및 재수행이란 불필요한 과정을 반복하게 되었다. 따라서 본 논문에서는 제안한 알고리즘은 데이터베이스의 용도에 맞게 직렬화 순서를 보장하여 스케줄을 관리하는 요청 2단계 로킹기법(Request Two-phase Locking)으로서 이는 2단계 로킹기법의 기본원리에 요청로크를 사용함으로 보다 효율적으로 병행제어를 할 수 있다. 여기서 요청로크는 각각의 트랜잭션 스케줄에 로크획득 및 해제를 병행수행제어의 필요에 따라 유동적으로 할 수 있으며, 읽기로크, 쓰기로크, 요청로크라는 3가지 로킹모드를 통해 대처방안을 마련함으로서, 충돌을 방지하며, 충돌연산의 특성에 따라 직렬화 순서를 동적으로 조정함으로 블록킹을 막는 병행제어를 응용하여 병렬성을 유지한다.