• Journal of applied mathematics & informatics
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• 제8권3호
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• pp.899-907
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• 2001

Complex variable methods are used to solve the first and the second fundamental problems for infinite plate with two holes having arbitrary shapes which are conformally mapped on the domain outside of the unit circle by means of rational mapping function. Some applications are investigated and some special cases are derived.

• 한국CDE학회논문집
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• 제9권4호
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• pp.397-405
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• 2004

Texture mapping is the process of covering 3D models with texture images in order to increase the visual realism of the models. For proper mapping the coordinates of texture images need to coincide with those of the 3D models. When projective images from the camera are used as texture images, the texture image coordinates are defined by a camera calibration method. The texture image coordinates are determined by the relation between the coordinate systems of the camera image and the 3D object. With the projective camera images, the distortion effect caused by the camera lenses should be compensated in order to get accurate texture coordinates. The distortion effect problem has been dealt with iterative methods, where the camera calibration coefficients are computed first without considering the distortion effect and then modified properly. The methods not only cause to change the position of the camera perspective line in the image plane, but also require more control points. In this paper, a new iterative method is suggested for reducing the error by fixing the principal points in the image plane. The method considers the image distortion effect independently and fixes the values of correction coefficients, with which the distortion coefficients can be computed with fewer control points. It is shown that the camera distortion effects are compensated with fewer numbers of control points than the previous methods and the projective texture mapping results in more realistic image.

• 한국통신학회논문지
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• 제29권12A호
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• pp.1340-1348
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• 2004

본 논문에서는 OFDM 시스템에서 최대전력 대 평균전력(Peak-to -average Power Ratio : PAPR) 및 계산량(computation)을 최소화하는 PAPR-최소화하는 시퀀스 매핑 기법을 제안한다. PAPR을 줄이기 위해, 낮은 신호 전력의 블락 지수(block index)와 심벌 패턴들에 관한 정보를 이용하여 사상(mapping table)을 작성한다. 입력 데이터 시퀀스는 목(quotient)과 나머지(remainder)을 찾기위해 블락 지수로 나눈다. 낮은 신호 전력의 심벌 패턴은 사상 표에서 음에 따른 블락 지수의 항으로 찾게되고, 수신기에서 최초의 데이터 시퀀스를 구별하고 복원하기 위한 추가정보처럼 나머지와 함께 전송된다. 본 논문에서는 두가지 방식의 사상(mapping) 기법을 제안한다. 하나는 OFDM 신호를 복원하기위해 송신기와 수신기 양쪽 다 사상 표를 갖는 기법이고, 다른 하나는 이동국(mobile) 시스템에서 부하와 복잡성을 줄이기 위해 단지 송신기만 사상 표를 사용하는 기법이다. 이들 알고리즘은 다중 캐리어 시스템에서 PAPR 경감, 단순 처리, 그리고 적은 계산량을 확인할 수 있었다.

• 한국측량학회지
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• 제35권2호
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• pp.91-102
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• 2017

Backpack-mounted mapping system is firstly introduced for flexible movement in indoor spaces where satellite-based localization is not available. With the achieved advances in miniaturization and weight reduction, use of LiDAR (Light Detection and Ranging) sensors in mobile platforms has been increasing, and indeed, they have provided high-precision information on indoor environments and their surroundings. Previous research on the development of backpack-mounted mapping systems, has concentrated mostly on the improvement of data processing methods or algorithms, whereas practical system components have been determined empirically. Thus, in the present study, a simulator for a LiDAR sensor (Velodyne VLP-16), was developed for comparison of the effects of diverse conditions on the backpack system and its operation. The simulated data was analyzed by visual inspection and comparison of the data sets' statistics, which differed according to the LiDAR arrangement and moving speed. Also, the data was used as input to a point-cloud registration algorithm, ICP (Iterative Closest Point), to validate its applicability as pre-analysis data. In fact, the results indicated centimeter-level accuracy, thus demonstrating the potentials of simulation data to be utilized as a tool for performance comparison of pointdata processing methods.

• 한국멀티미디어학회논문지
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• 제25권10호
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• pp.1395-1403
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• 2022

Lately, over 4K high definition and high dynamic range (HDR) display devices are popularized, various interpolation and HDR methods have been researched to expand the size and the dynamic range. Since most of the legacy low resolution (LR) images require both an interpolation and a HDR tone mapping methods, the two processes should be subsequently applied. Therefore, the proposed algorithm presents a HDR up-scaling algorithm using undecimated wavelet transform and Retinex method, which transfers a LR image of low dynamic range (LDR) into the high resolution (HR) with HDR. The proposed algorithm consists of an up-scaling scheme increasing the image size and a tone mapping scheme expanding the dynamic range. The up-scaling scheme uses the undecimated version of the simplest Haar wavelet analysis for the 8-directional interpolation and the change region is extracted during the analysis. This region information is utilized in controlling the surround functions' size of the proposed tone mapping using MSRCR, to enhance the pixels of around the edges that are dominant feature of the subjective image quality. As the results, the proposed algorithm can apply an up-scaling and tone mapping processes in accordance with the type of pixel.

• 한국측량학회지
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• 제35권4호
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• pp.319-326
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• 2017

SAR (Synthetic aperture radar) images are less affected by the weather compared to optical images and can be obtained at any time of the day. Therefore, SAR images are being actively utilized for military applications and natural disasters. However, because SAR data are in grayscale, it is difficult to perform visual analysis and to decipher details. In this study, we propose a color mapping method using RF (random forest) regression for enhancing the visual decipherability of SAR images. COSMO-SkyMed 2 and WorldView-3 images were obtained for the same area and RF regression was used to establish color configurations for performing color mapping. The results were compared with image fusion, a traditional color mapping method. The UIQI (universal image quality index), the SSIM (structural similarity) index, and CC (correlation coefficients) were used to evaluate the image quality. The color-mapped image based on the RF regression had a significantly higher quality than the images derived from the other methods. From the experimental result, the use of color mapping based on the RF regression for SAR images was confirmed.

• 한국멀티미디어학회논문지
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• 제18권8호
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• pp.950-959
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• 2015

The necessity of an empirical study on how projection mapping videos are evaluated from consumers' point of view has arisen, as they can lead to visual pollution if factors including spatial characteristics around the structure and details of the contents are not taken into consideration. This study aims to evaluate projection mapping videos and elucidate the question on whether evaluation criteria positively influence the satisfaction level or not. Above all, five evaluation criteria including artistry, creativity, identity, immersion and usefulness were deducted and a hypothesis from preceding research "each evaluation criteria will positively(+) influence the satisfaction level of projection mapping video" has been established. In order to test the hypothesis, big domestic department stores which screened projection mapping videos were selected and a verification experiment has been conducted with ordinary citizens as subjects. In the result of the experiment, among the five evaluation criteria, artistry, creativity, and usefulness were chosen, while identity and immersion were dismissed. The result verifies that if useful information is provided in forms of interesting contents produced with distinctive ideas and creative methods, it will satisfy the consumers as attractive public design.

• 천문학회보
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• 제41권1호
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• pp.70.4-71
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• 2016

The links between super-massive black hole masses and their host galaxy properties are observed, indicating that black hole growth and host galaxy evolution are closely related. Reverberation mapping, which uses the time delay from the central black hole to broad line regions, is one of the best methods to estimate masses of black holes of active galactic nuclei (AGNs). However, only masses of about 50 black holes have been determined in reverberation mapping studies so far, and most of them are limited to optical luminosities below 10^45 erg/s due to the challenges of long-term time domain observations in both photometry and spectroscopy. In this project, we expand reverberation mapping samples to higher luminosities of > 10^44.5 erg/s at 0.1 < z < 0.35, that have expected time lags of 40 - 250 light days. Photometric (using LOAO 1-m and MDM 1.3-m) and spectroscopic (using MDM 2.4-m and Lick 3-m) monitoring campaigns are being conducted for a 3 year duration and 20 day cadence. Precedent photometric observations in 2015B show some targets with variability and follow-up spectroscopic observations are on-going. In this presentation, we introduce our project, present reverberation mapping simulation results, and preliminary results on photometry. These reverberation mapping masses of relatively high luminous AGNs will provide a strong constraint on black hole mass calibration, e.g., the single-epoch mass estimation.

• 지질공학
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• 제24권3호
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• pp.343-351
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• 2014

터널 시공 중 막장 매핑은 터널의 위험도 판단과 향후 지보패턴 결정에 중요한 역할을 한다. 본 연구에서는 막장관찰기록지를 이용한 기존의 수기 매핑 방식을 탈피하여 모바일을 이용한 디지털 매핑 시스템을 제시하였다. 현장에서 디바이스를 기반으로 작성된 매핑 자료는 메인서버와 연동되어 자동으로 데이터베이스화가 되며 담당자 및 관련전문가들 사이에서 실시간 피드백이 가능하도록 구현하였다. 매핑의 정밀한 표현 방식 및 다량의 데이터 누적에 의한 속도 저하 문제는 Douglas-Peucker 알고리즘 등을 이용하여 해결하고자 하였다. 본 시스템은 향후 다양한 현장 검증 및 추가적인 기능 개선 등을 통해 완성도가 높아질 것으로 기대된다.

• 영어어문교육
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• 제7권1호
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• pp.137-160
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• 2001

This paper is to suggest the way to improve EFL reading skill through semantic mapping by leveled group activities. Semantic mapping is a categorical structuring of information in graphic forms or diagrams. It can be used to activate and organize background knowledge on topics in classrooms. For small group activities, the class is divided into higher leveled groups and lower leveled groups of four members based on their grades. The teaching process has three stages: Pre-reading, while-reading, and post-reading. In the pre-reading stage, students discuss what they know about the topic. They map ideas with a brainstorming technique. In the while-reading stage, they read the text about the topic. While they are reading, they could ask some questions they might have and discuss the information in the text and categorize them with semantic mapping. In the post-reading stage, they discuss what they thought of the topic and add some information about the topic with semantic mapping. For the subjects of this study, third grade, middle school students were selected: 41 students for the experimental group and 35 students for the control group. The experimental period covered almost one semester from March to August, 2000. The results were as follows: 1) The students in the experimental group had higher scores in reading comprehension than those in the control group when semantic mapping was used; 2) The use of semantic mapping in reading comprehension was found to be much more effective in the higher leveled group than in the lower leveled group; 3) The results of questionnaires showed that many students became more interested and motivated in English, and semantic mapping helped them to participate positively in reading the English text. Thus, using semantic mapping by leveled group activities can be an effective alternative to traditional teaching methods for teachers who desire to improve reading skill in middle school students' English classes.