• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7C
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• pp.921-930
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• 2004

In this paper, a robust video transmission system is proposed. To effectively prevent the corruption of video stream and its propagation in spatial and temporal domains, a version of turbo code, so-called as byte-aligned variable-length turbo code, is applied. Protection performance of the proposed turbo code is first evaluated by applying it to GOB-based variable-size ITU-T H.263+ video packets, where the protection level is statically controlled based on the joint source-channel criteria. This protection is then extended to support the adaptation of code ratio to best match the time-varying channel condition. The time-varying Rayleigh fading channel is modelled considering the correlation of the fading channel. The resulting performance comparison with the static turbo code as well as the conventional RCPC code clearly demonstrates the possibility of the proposed adaptation approach for the time-varying correlated Rayleigh-fading channel.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.12 no.1
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• pp.49-53
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• 2012

X-linked adrenoleukodystrophy (ALD) is a rare inherited metabolic disease which results in impaired peroxisomal ${\beta}$-oxidation and the accumulation of very long chain fatty acids (VLCFA) in the adrenal cortex, the myelin of the central nervous system, and the testes. X-linked ALD is caused by mutations in the ABCD1 gene encoding an ATP-binding cassette transporter superfamily located in the peroxisomal membrane. This disease is characterized by a variety of phenotypes. The classic childhood cerebral ALD is a rapidly progressive demyelinating condition affecting the cerebral white matter before the age of 10 years in boys. We report the case of a 8-year-old with childhood cerebral X-linked ALD who developed inattention, hyperactivity, motor incoordination and hemiparesis. We diagnosed ALD with elevated plasma very long chain fatty acid level and diffuse high signal intensity lesions in both parieto-occipital white matter and cerebellar white matter in brain MRI. We identified a novel c.983delT (p.Met329CysfsX7) mutation of the ABCD1 gene. There is no correlation between X-ALD phenotype and mutations in the ABCD1 gene. Further studies for searching additional non-genetic factor which determine the phenotypic variation will be needed.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.161-170
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• 2023

We attempted to estimate the carbon accumulation of Hibiscus hamabo and Paliurus ramosissimus, semimangroves native to Jeju Island, by remote sensing and to build an artificial intelligence model that predicts its spatial variation with climatic factors. The aboveground carbon accumulation of semi-mangroves was estimated from the aboveground biomass density (AGBD) provided by the Global Ecosystem Dynamics Investigation (GEDI) lidar upscaled using the normalized difference vegetation index (NDVI) extracted from Sentinel-2 images. In Jeju Island, carbon accumulation per unit area was 16.6 t C/ha for H. hamabo and 21.1 t C/ha for P. ramosissimus. Total carbon accumulation of semi-mangroves was estimated at 11.5 t C on the entire coast of Jeju Island. Random forest analysis was applied to predict carbon accumulation in semi-mangroves according to environmental factors. The deviation of aboveground biomass compared to the distribution area of semi-mangrove forests in Jeju Island was calculated to analyze spatial variation of biomass. The main environmental factors affecting this deviation were the precipitation of the wettest month, the maximum temperature of the warmest month, isothermality, and the mean temperature of the wettest quarter. The carbon accumulation of semi-mangroves predicted by random forest analysis in Jeju Island showed spatial variation in the range of 12.0 t C/ha - 27.6 t C/ha. The remote sensing estimation method and the artificial intelligence prediction method of carbon accumulation in this study can be used as basic data and techniques needed for the conservation and creation of mangroves as carbon sink on the Korean Peninsula.

• Investigative Magnetic Resonance Imaging
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• v.10 no.2
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• pp.108-116
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• 2006

Purpose : High-resolution spiral-scan imaging is performed at 3 Tesla MRI system. Since the gradient waveforms for the spiral-scan imaging have lower slopes than those for the Echo Planar Imaging (EPI), they can be implemented with the gradient systems having lower slew rates. The spiral-scan imaging also involves less eddy currents due to the smooth gradient waveforms. The spiral-scan imaging method does not suffer from high specific absorption rate (SAR), which is one of the main obstacles in high field imaging for rf echo-based fast imaging methods such as fast spin echo techniques. Thus, the spiral-scan imaging has a great potential for the high-speed imaging in high magnetic fields. In this paper, we presented various high-resolution images obtained by the spiral-scan methods at 3T MRI system for various applications. Materials and Methods : High-resolution spiral-scan imaging technique is implemented at 3T whole body MRI system. An efficient and fast higher-order shimming technique is developed to reduce the inhomogeneity, and the single-shot and interleaved spiral-scan imaging methods are developed. Spin-echo and gradient-echo based spiral-scan imaging methods are implemented, and image contrast and signal-tonoise ratio are controlled by the echo time, repetition time, and the rf flip angles. Results : Spiral-scan images having various resolutions are obtained at 3T MRI system. Since the absolute magnitude of the inhomogeneity is increasing in higher magnetic fields, higher order shimming to reduce the inhomogeneity becomes more important. A fast shimming technique in which axial, sagittal, and coronal sectional inhomogeneity maps are obtained in one scan is developed, and the shimming method based on the analysis of spherical harmonics of the inhomogeneity map is applied. For phantom and invivo head imaging, image matrix size of about $100{\times}100$ is obtained by a single-shot spiral-scan imaging, and a matrix size of $256{\times}256$ is obtained by the interleaved spiral-scan imaging with the number of interleaves of from 6 to 12. Conclusion : High field imaging becomes increasingly important due to the improved signal-to-noise ratio, larger spectral separation, and the higher BOLD-based contrast. The increasing SAR is, however, a limiting factor in high field imaging. Since the spiral-scan imaging has a very low SAR, and lower hardware requirements for the implementation of the technique compared to EPI, it is suitable for a rapid imaging in high fields. In this paper, the spiral-scan imaging with various resolutions from $100{\times}100$ to $256{\times}256$ by controlling the number of interleaves are developed for the high-speed imaging in high magnetic fields.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.3
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• pp.328-335
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• 2007

Ontology is represented by the shared concepts and relations among those. Many studies have been actively working on sharing human's knowledge with that of systems by using it. For a typical example, there is the design and implementation of ontology system for image understanding. However conventional studies on ontology-based image understanding have proposed not concrete methods but conceptual idea. In this paper, we propose an ontology-based image understanding system with following four processes: i)knowledge representation of a specific domain by the ontology, ii)feature extraction of objects through image processing and image analysis, iii)image interpretation by object features, and iv)reduction of ambiguity existing in image interpretation by ontology reasoning. We implement an image understanding system based on the proposed processed, and show the effectiveness of the proposed system from experimental results in a specific domain.

• Analytical Science and Technology
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• v.16 no.3
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• pp.212-217
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• 2003

The memory effect of silver and aqua regia in the vessel by their permeation was studied during the microwave digestion of samples under the operating conditions of high temperature and pressure. The extent of permeation in vessels with the solution containing silver 5 mg has been shown to be $0.97{\mu}g/mL$ for the digestion of $HNO_3$ solution and $0.47{\mu}g/mL$ for the digestion of oil sample under condition of MDS 180T program ($180^{\circ}C$, 220 psi).

• Proceedings of the Korea Contents Association Conference
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• 2013.05a
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• pp.413-414
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• 2013

본 연구는 C.P.N.T측면에서 싸이의 뮤직비디오 그리고 문화적인 요소의 성공요인들에 대해서 분석했다. 연구결과, 싸이의 뮤직비디오에는 재미, 유머, 음악과 춤의 반복성 등 창의적인 콘텐츠를 보여주었으며, 플랫폼으로는 YG의 유투브 직접 제작 참여로 수용자의 시청에 부담 없게 접근이 용이하게 고화질 저용량으로 보급하였습니다. 네트워크측면에서는 트위터와 페이스북과 같은 다양한 서비스를 통하여 빠른 속도와 장소에 구애받지 않고 유통망을 형성했으며, 매스미디어 NBC방송에 유투브 영상이 소개됨으로 싸이의 뮤직비디오와 음악이 단순한 UCC영상의 평범함에서 대중적이고 혁신적인 상징의 이미지로 급부상하게 된다. 또한 아이패드, 스마트폰, N스크린 등 많은 터미널을 통해 싸이의 강남스타일 뮤직비디오와 음악은 수용자의 시각과 청각을 만족시켜주어 성공하게 된다.

• KOMUNHWA
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• no.93
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• pp.153-184
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• 2019

The Yunggimuntogi(Treasure No. 597) has been known to be recovered at Yeongseondong Shell Mounds, Busan in 1933 during the Japanese colonial period. This artifact is characterized by a short spout attached to one side of the mouth rim as well as a V-shaped clay stripe on the upper body part, which is the only earthenware designated as national cultural heritage from the prehistoric period. In order to prepare for the earthquakes that have recently become more frequent, this study has precisely diagnosed the conservation status and stabilized the artifact through scientific conservation treatment. As a result of the precise diagnosis of the preservation status, cracks and losses were observed in the spout, the mouth rim, and the base. In some portion of the raised pattern decorations, loss of fine pieces raised concerns over the secondary damage. The C·T image analysis has shown that the earthenware had been once glued and restored from dozens of broken pieces. From the sites restored in the past, the peeling of surface colored layer and the fine cracks between the restoration material and the earthenware clay were observed due to the aging of the restoration material. Furthermore, the inherent color and texture of the earthenware was altered by excessive color matching. The damaged and restored sites were concentrated on the left side, the rear side, and the right side. The damages were more severe on the base than the body portion. In the past, gypsum(CaSO4) had been mainly used as restoration material, and synthetic resin had been partially used for joining and reinforcing the pieces. On the surface of the restoration sites, it is presumed that lead chromate(PbCrO4) yellow modern pigment was used for color matching. The precise diagnosis has revealed that the restoration material in the past has been stabilized by interlocking with the earthenware clay for a long time. Therefore, in this conservation treatment, the coloring layer of the excessively painted surface was washed to recover the original color and texture of the earthenware, and the physically vulnerable parts of the sites restored in the past were mainly targeted for joining and restoration. The conservation treatment has proceeded in the order of cleaning, joining and restoration, and color matching, and materials and methods suitable for the artifacts were selected and applied through a preliminary experiment. The survey on conservation status before the treatment as well as the conservation treatment process have been systematically recorded and documented to provide basic data for further continuous conservation and maintenance by collecting institutions.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.550-554
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• 1997

Acoustic or sound noise due to gradient pulsing has been one of the problems in MRI, both in patient scanning as well as in many areas of psychiatric and neuroscience research, such as unctional MRI (fMRI). Our recent observations in MRI or the visual and motor cortex show very different results with sound noise in comparison with the results obtained without sound noise. Although a number of ideas has been suggested in the literature about the possible elimination or reduction of sound noise, progress has been slow due to the basic role of gradient pulsing in MR imaging. Therefore, we report on some typical behavior of sound noise observed from MRI scanners and the analyses of their characteristics. Data are obtained both from a commercial MRI scanner (GE Signa 1.5-T EPI system).

• Electronics and Telecommunications Trends
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• v.31 no.1
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• pp.45-57
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• 2016

스마트폰을 포함한 고성능 모바일 기기들이 급속하게 증가하고, 통신사업자의 네트워크를 경유하지 않더라도 주변 기기 간 직접(Point-to-Point: P2P) 통신을 지원하는 다양한 방식의 통신기능이 스마트폰, 카메라 등 다양한 기기에 탑재됨에 따라 근접통신 기반의 다양한 신규 서비스들이 출현될 것으로 예상된다. 또한, 주변의 IoT 기기들과도 직접통신을 통해 정보를 교환하는 등 동영상, 음악 등의 큰 용량의 미디어를 통한 생활정보 획득이 일상화되고 있다. 모바일 사용자들이 미디어 정보를 네트워크 기반의 정보 소통이 아닌, 모바일/IoT 기기 간 직접 정보를 전달함으로써 네트워크의 부하를 경감하고, 사용자의 정보전달이 근접거리에서 보다 안전하게 소통되어 편리한 ICT 일상생활로 변화할 것이다.