• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.1
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• pp.44-49
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• 2016

This paper proposed the method to improve performance of a pixel, which has low accuracy, by applying image segmentation methods based on color and multi-threshold of brightness. Stereo matching is the process to find the corresponding point on the right image with the point on the left image. For this process, distance(depth) information in stereo images is calculated. However, in the case of a region which has textureless, stereo matching has low accuracy and bad pixels occur on the disparity map. In the proposed method, the relationship between adjacent pixels is considered for compensating bad pixels. Generally, the object has similar color and brightness. Therefore, by considering the relationship between regions based on segmented regions by means of color and multi-threshold of brightness respectively, the region which is considered as parts of same object is re-segmented. According to relationship information of segmented sets of pixels, bad pixels in the disparity map are compensated efficiently. By applying the proposed method, the results show a decrease of nearly 28% in the number of bad pixels of the image applied the method which is established.

• Journal of Digital Contents Society
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• v.15 no.2
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• pp.251-261
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• 2014

In the typical P2P VOD system, it is very important to develop the fast and efficient peer searching scheme since the peers frequently join and leave to/from P2P system. This paper proposes a new peer searching scheme for P2P VOD system based on DHT network environment. The proposed scheme constructs DHT network by managing the peers having close playback starting times and close network locations into a peer all together. The peer information is mapped onto DHT nodes by hashing the key values each of which consists of the starting time and network location of the peer. From the simulation results, the number of messages required to search the partner peers are decreased, and the number of buffer maps exchanging among the peers are also decreased. The proposed scheme can reduce the average network distances among the partner peers. As a result, the proposed scheme makes routing more efficient and it saves the network resources by decreasing communication traffic overhead.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.6
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• pp.1-7
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• 2011

The depth camera measures range information of the scene in real time using Time-of-Flight (TOF) technology. Measured depth data is then regularized and provided as a depth image. This depth image is utilized with the stereo or multi-view image to generate high-resolution depth map of the scene. However, it is required to correct noise and distortion of TOF depth image due to the technical limitation of the TOF depth camera. The corrected depth image is combined with the color image in various methods, and then we obtain the high-resolution depth of the scene. In this paper, we introduce the principal and various techniques of sensor fusion for high-quality depth generation that uses multiple camera with depth cameras.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.8
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• pp.741-757
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• 2016

Over 60 years has passed since mankinds started space exploration beyond the Earth with lunar explorer Luna 1 launched by Soviet Union. Unprecedently remarkable outcomes have been obtained by sending unmanned spacecrafts to most planets in the solar system and having the lander landed on the approaching comet toward the Earth even though any evidence of life presence has not been discovered yet. Only moon is an natural object beyond the earth on which human beings landed. Many countries are planning to send humans to the moon or mars to build colonies and to survive with substantiality. Korean lunar exploration program has officially started as of 2016 after its plan including lunar exploration has been specified in the series of National Space Promotion Plan since Korea initiated space development in early 1990s. In this paper, the plan for Korean space exploration is summarized with reviewing overseas space exploration program status and trends.

• Journal of Satellite, Information and Communications
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• v.10 no.2
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• pp.24-29
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• 2015

Recently, with developments of various networks, devices and various services, energy efficiency has become one of the most crucial issues with respect to sustainability of mobile devices. For connecting to networks seamlessly to offer services, a scenario of RF energy harvesting which supplies energy to wireless devices with RF signals is assumed. To increase the efficiency of RF energy harvesting, this paper proposes a RF energy harvesting algorithm which is based upon a frequency selective fading map. Through the algorithm, a receiver of mobile device can get fading information at each frequency and select a frequency which has the best quality. At the end, the simulation result demonstrates its superiority by showing a 4.45dB improvement in comparison to a deep fading frequency point.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.167-185
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• 2016

$CO_2$ 지중저장 기술은 가장 유력한 대용량 온실가스 감축기술의 하나이다. 이 기술을 적용하여 국제적으로 노르웨이, 알제리, 캐나다, 미국 등에서 이미 대규모 실증 및 상용화 사업이 수행되고 있으며, 호주, 일본, 네덜란드, 독일 등 그 밖의 여러 나라에서 다양한 내용과 규모를 갖는 중소규모 실증사업이 진행되고 있다. 한국도 소규모 육상 파일럿 저장 프로젝트와 중규모 해상 저장실증 프로젝트가 추진되어 착실하게 기술개발과 경험확보를 위해 노력하고 있다. $CO_2$ 지중저장 사업은 화석연료의 사용이 다른 에너지원으로 대체되기 전까지 지속적으로 확장될 것으로 예측되고 있으나, 온실가스 감축시장의 불안전성, 사업의 수익구조와 관련된 경제성, 누출에 대한 안전성 등의 위협요소를 갖고 있다. 따라서 이러한 위협을 극복하기 위해 많은 국가와 기업들이 저비용-고효율 지중저장 기술과 안전한 지중저장 기술의 확보를 목표로 연구개발 및 실증사업을 추진하고 있다. 한국의 경우에 저장소가 주요 포집원으로부터 상당한 거리를 갖고 있는 해저에 발달하고 있기 때문에 지중저장 사업의 경제성 확보가 매우 불리한 조건이다. 따라서 정부나 기업이 CCS 기술을 주요 온실가스 감축수단으로 채택하여 대규모 지중저장 사업을 본격적으로 착수하는 것을 주저하고 있다. 한국과 같은 불리한 조건을 갖는 국가의 경우에 특히 대규모 저장소의 확보를 포함한 저비용-고효율 지중저장 기술의 실용화가 절실하게 필요하다. 결론적으로 한국의 $CO_2$ 지중저장 사업의 성공적인 추진을 위해서는 대규모 저장소의 확보, 저비용-고효율 지중저장 기술의 개발과 실증을 통한 실용화, 중소규모 지중저장 실증사업으로 축적한 기술과 경험으로 대규모 지중저장 사업의 효율화 달성이 요구된다. 이를 위한 실천적인 로드맵과 프로그램의 작성과 착실한 이행 역시 중요하다. 이러한 기반이 착실하게 다져질 경우에 한국에서 대규모 CCS 통합실증과 $CO_2$ 지중저장 사업이 본격적으로 개시될 수 있을 것이다.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.1
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• pp.23-28
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• 2017

Shape from focus (SFF) is a technique used to reconstruct 3D shape of objects from a sequence of images obtained at different focus settings of the lens. In this paper, a new shape from focus method for 3D reconstruction of microscopic objects is described, which is based on gradient operator in Mathematical Morphology. Conventionally, in SFF methods, a single focus measure is used for measuring the focus quality. Due to the complex shape and texture of microscopic objects, single measure based operators are not sufficient, so we propose morphological operators with multi-structuring elements for computing the focus values. Finally, an optimal focus measure is obtained by combining the response of all focus measures. The experimental results showed that the proposed algorithm has provided more accurate depth maps than the existing methods in terms of three-dimensional shape recovery.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.4
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• pp.463-468
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• 2010

The mobile robot which accomplishes a work in explored region does not know location information of surroundings. Traditionally, simultaneous localization and mapping(SLAM) algorithms solve the localization and mapping problem in explored regions. Among the several SLAM algorithms, the EKF (Extended Kalman Filter) based SLAM is the scheme most widely used. The EKF is the optimal sensor fusion method which has been used for a long time. The odometeric error caused by an encoder can be compensated by an EKF, which fuses different types of sensor data with weights proportional to the uncertainty of each sensor. In many cases the EKF based SLAM requires artificially installed features, which causes difficulty in actual implementation. Moreover, the computational complexity involved in an EKF increases as the number of features increases. And SLAM is a weak point of long operation time. Therefore, this paper presents a symmetrical model based SLAM algorithm(called M-SLAM).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1442-1449
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• 2007

Shadows are important elements for realistic rendering of the 3D scene. We cannot recognize the distance of objects in the 3D scene without shadows. Two methods, image-based medthods and object-based methods, are largely used for the rendering of shadows. Object based methods can generate accurate shadow boundaries. However, it cannot be used to generate the realtime shadows because the time complexity defends on the complexity of the 3D scene. Image based methods which are techniques to generate shadows are widely used because of fast calculation time. However, this algorithm has aliasing problems. PCF is a method to solve the aliasing problem. Using PCF technique, antialiased shadow boundaries can be generated. However, PCF with large filter size requires more time to calculate antialiased shadow boundaries. This paper proposes an improved PCF technique which generates antialiased shadow boundaries similar to that of PCF. Compared with PCF, this technique can generate antialiased shadows in less time.

• Journal of Convergence for Information Technology
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• v.11 no.10
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• pp.45-52
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• 2021

In this paper, we proposed an Atrous Residual U-Net (AR-UNet) to improve the segmentation accuracy of semantic segmentation method based on U-Net. The U-Net is mainly used in fields such as medical image analysis, autonomous vehicles, and remote sensing images. The conventional U-Net lacks extracted features due to the small number of convolution layers in the encoder part. The extracted features are essential for classifying object categories, and if they are insufficient, it causes a problem of lowering the segmentation accuracy. Therefore, to improve this problem, we proposed the AR-UNet using residual learning and ASPP in the encoder. Residual learning improves feature extraction ability and is effective in preventing feature loss and vanishing gradient problems caused by continuous convolutions. In addition, ASPP enables additional feature extraction without reducing the resolution of the feature map. Experiments verified the effectiveness of the AR-UNet with Cityscapes dataset. The experimental results showed that the AR-UNet showed improved segmentation results compared to the conventional U-Net. In this way, AR-UNet can contribute to the advancement of many applications where accuracy is important.