• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.5
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• pp.249-255
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• 2017

Using a magnetic separation process, pond ash generated in thermoelectric power plants was separated into magnetic materials and nonmagnetic materials in order to make it into a raw material of geopolymers and unburned carbon; screening characteristics according to the particle sizes and magnet strength levels of the pond ash were observed. Based on the results of magnetic separation into fine particle (0.15~0.84 mm) and rough particle (0.84~2.4 mm) pond ash using 3000 G magnets, the weight fraction and ignition loss of nonmagnetic materials were found to be higher than those of magnetic materials, regardless of the particle size. In the case of fine particle pond ash, when the magnet strength was increased from 3000 G to 10000 G, even those materials that were weakly magnetic were separated into magnetic materials, leading to drastic increases in the weight fraction of magnetic materials, such that the ignition loss accounted for 66.9 % (22.8 wt%) of the entire ignition loss of 32.6 wt%, despite of the low ignition loss. Based on the results of measurement of the compressive strength levels of geopolymers made of magnetic-separated rough particle pond ash, the compressive strength of geopolymers made of magnetic materials containing small amounts of unburned carbon was found to be 20 MPa.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.4
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• pp.627-639
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• 1996

Charateristics of Ansan and Boryong coal fly ashes collected at different seasons were investigated for the recycling them as ceramic raw materials. The effect of pH treatment on the classification of Ansan coal fly ashes by elutriation was discussed. Charateristics of ansan and boryong coal fly ashes were not significantly changed with power plants and seasons. major crystalline phases were mullite and quartz. These results suggested that coal fly ashes cab be used as raw materials instead of clay minerals. However, particle size distribution was very broad from a few $\mu\textrm{m}$ to over $100\;\mu\textrm{m}$. Especially, ansan coal fly ashes have various morphologies. Therefore, coal fly ashes should be classified before using as raw materials. Because of higher dispersion by pH treatment, spherical cenospheres were mainly collected in the 4th step and particle size distribusion was also decreased by elutriation for the ansan coal fly ashes. The specific surface area of the sample collected in the 4th step was $1.24\;m^{2}/g$ which was smaller than that of not treated Ansan coal fly ashes.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.4
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• pp.414-422
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• 1995

Coal fly ash was calcined and elutriated for recycling as ceramic raw materials. C Crystal phases, morphologies, chemical components, particle size distributions and Ig. loss of as-received, calcined and elutriated coal fly ash were investigated to study the effects of the calci nation and elutriation on the coal fly ash classification. The experimental equations, which were used in elutriation of clay, were examined in order to find out which equation is appropriated for coal fly ash classification. It turned out that Rittinger's equation is relatively well matched for the fly ash. Having nothing to do with the treatment conditions, the crystal phases of coal f fly ash were mullite, quartz. Calcite peak was detected in as - received and elutriated coal fly a ash; however, it disappeared in calcined coal fly ash. As - received coal fly ash consists of various type of particles such as a cenosphere, coke type, silicate type, whisker type and aggregat e ed type. In case of calcined coal fly ash, coke type particles were eliminated and agglomerated type particles were relatively increased. Most of the particles that were relatively spherical cenosphere in the 4th step of elutriator. Particle size distribution was narrowed by calcination a and elutriation. Especially, in elutriation, particle size distribution was very narrow.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.4
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• pp.581-587
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• 2021

Real-time video streaming scheme for multimedia content delivery and remote conference services is one of technologies that are significantly sensitive to data transmission delay. Recently, because of COVID-19, real-time video streaming contents for the services are significantly increased such as personal broadcasting and remote school class. In order to support the services, there is a growing emphasis on low transmission delay and secure content delivery, respectively. Therefore, our research proposed a packet aggregation algorithm to reduce the transmission delay of selectively encrypted video transmission for real-time video streaming services. Through the application of the proposed algorithm, the selectively encrypted video framework can control the amount of MPEG-2 TS packets for low latency transmission with a consideration of packet priorities. Evaluation results on testbed show that the application of the proposed algorithm to the video framework can reduce approximately 11% of the transmission delay for high and low resolution video.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.07a
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• pp.13-16
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• 2015

본 논문에서는 어휘의 동시 발생 (co-occurrence) 빈도와 분포를 이용한 회의록 요약방법을 제안한다. 회의록은 일반 문서와 달리 문서에 여러 세부적인 주제들이 나타나며, 잘못된 형식의 문장, 불필요한 잡담들을 포함하고 있기 때문에 이러한 특징들이 문서요약 과정에서 고려되어야 한다. 기존의 일반적인 문서요약 방법은 하나의 주제를 기반으로 문서 전체에서 가장 중요한 문장으로 요약하기 때문에 다중 주제 회의록 요약에는 적합하지 않다. 제안한 방법은 먼저 어휘의 동시 발생 (co-occurrence) 빈도를 이용하여 회의록 분할 (segmentation) 과정을 수행한다. 다음으로 주제의 구분에 따라 분할된 각 영역 (block)의 중요 단어 집합 생성, 중요 문장 추출 과정을 통해 회의록의 중요 문장들을 선별한다. 마지막으로 추출된 중요 문장들의 위치, 종속 관계를 고려하여 최종적으로 회의록을 요약한다. AMI meeting corpus를 대상으로 실험한 결과, 제안한 방법이 baseline 요약 방법들보다 요약 비율에 따른 평가 및 요약문의 세부 주제별 평가에서 우수한 요약 성능을 보임을 확인하였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.2
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• pp.185-201
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• 1993

The objectives of this study are to identify the physical, chemical and microstructural properties of coal fly ash and to increase the industrial use of coal fly ash. Experimental results show that 3 major constituents of coal fly ash are $SiO_2$, $Al_2O_3$ and coal fly ash includes the crystalline of Quartz and Mullite. Coal fly ash are classified into 7 groups based on the type of microstructure. Cenosphere is divided into floater and dry separated cenosphere which are consist mainly of $SiO_2$ and $Al_2O_3$. Cenosphere segregations are formed by adsorption and neck growth of the smaller sized cenosphere particles on the condition of the high temperature and air pressure.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.2
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• pp.24-29
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• 2009

Sound source localization system is used in a robot, a video conference and CCTV(Closed-circuit television) systems. In this Sound source localization systems are applied to human and they can receive a number of sound data frames during speaking. In this paper, we propose methods which is reducing angle estimation error by selecting sound data frame which can more precisely compute the angles from inputted sound data frame. After selected data converted to angle, the error of sound source localization recognition system can be reduced by applying to medium filter. By the experiment using proposed system it is shown that the average error of angle estimation in sound source recognition system can be reduced up to 31 %.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.05a
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• pp.184-187
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• 2020

본 논문에서는 실시간 얼굴인식 기술을 활용한 인물 선별 송출 시스템을 제안한다. 실시간 동영상 안에 등장하는 다수의 인물 객체 얼굴을 검출하고 인식하기 위해 Haar 특징 정보 기반의 다단계(Cascade) 학습 알고리즘을 사용한다. 이 시스템은 다수의 인물을 인식하고 학습할 수 있으며 인식된 각 인물의 송출 여부를 사용자가 직접 선택할 수 있는데 이 모든 선택 송출 과정을 실시간으로 처리할 수 있다. 여기에서 제시한 기술은 다자간 화상 채팅이나 다자간 화상 회의에서 특정인의 프라이버시 보호를 위한 기술로 활용될 수 있다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2021.11a
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• pp.198-200
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• 2021

해양산업 전반에 디지털라이제이션이 도입됨에 따라 새로운 기술이 선박, 항만에 가파르게 적용되고 있다. 하지만 현재의 규정 프레임워크는 선원이 중심이 되어 운영되는 선박을 기준으로 구성되어 있어 새로운 기술을 적용하는데 규정적 측면에서 제한 사항이 많다. 새로운 디지털기술을 적용하기 위해 국제해사기구의 해사안전위원회에서는 98차 회의에서 자율운항선박 운항을 위해 규정식별작업(RSE)을 진행하였고 최근 103차 회의에서 작업을 완료하였다. 이 작업을 통해 자율운항선박을 운항하기 위한 주요 이슈를 선별하고 향후 작업에서 논의하기로 하였다. 국제협약을 수용하는 체계를 갖는 우리나라의 해사 관련법은 국제해사기구의 이런 논의는 상당한 영향을 가져올 것으로 예상된다. 따라서 새로운 기술 및 운용 기술을 해사산업에 적용하기 위해서는 우리나라의 해사 관련법을 분석하여 주요 이슈 및 향후 작업계획수립이 요구된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.445-453
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• 2017

The Korean government's recent R&D policy has focused on encouraging government-funded research institutes (GRIs) to develop mid-term, long-term, and large-scale R&D projects. It is necessary to prepare thoroughly for the new R&D strategy, but there is no systematic accumulation of planning expertise, and there has been continued demand for good examples of research planning. Therefore, this study analyzes the reports of preliminary feasibility for government R&D programs through a meta-analysis of detailed evaluation items and contents to help researchers enhance their project-planning ability. The evaluation items that can be applied to R&D planning for GRI were reviewed, and twelve detailed evaluation items were selected through content analysis. The results of this study could contribute to practical R&D project planning and the improvement of evaluations.