• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.51
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• pp.89-97
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• 1999

Recently, due to the rapid technological progress, CDMA cellular system is widely used for voice, data and multimedia services. But the analysis for voice-data integrated traffic has not been done satisfactorily. Moreover, there is few research results for voice-data integrated traffic. In this paper, we propose an effective channel allocation algorithm for CDMA cellular system which serves voice-data integrated traffic. As for the proposed channel allocation algorithm, new calls and hand-off calls first attempt to connect micro-cell. We model the channel allocating scheme as a Birth-and-Death process. We reserve a few hand-off dedicated channels and calculate the blocking probability of hand-off calls varying the number of hand-off dedicated channels. Then we decide the number of hand-off dedicated channels satisfying the proper QoS(Quality of Service) and minimum blocking probability.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2017.11a
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• pp.413-421
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• 2017

4차 산업혁명과 관련하여 대두되는 핵심기술로 인공지능, 로봇, 빅데이터, 사물인터넷(IoT), 가상현실(VR)과 증강현실(AR), 자율주행자동차, 드론, 3D 프린팅, 블록체인 등을 들고 있다. 과거와 현재는 생산자가 최적의 비용으로 고성능 고품질 상품과 서비스를 제공했으나 4차 산업 혁명 시대는 소비자가 제품의 종류 및 특성, 생산 시점 등 전 과정에 관여하고 상품 자체보다 상품이 제공하는 가치를 중시하게 될 것으로 예상되고 있다. 이처럼 생산자 중심에서 소비자 중심으로 소비 트렌드가 변한 것은 AI, IoT, VR, 3D 프린팅 등 4차 산업혁명의 기술혁명이 지대한 기여를 했기 때문으로 볼 수 있다. 이처럼 다양한 제품과 서비스에서 새로운 유형의 소비자문제도 발생하고 기존의 소비자문제도 발생할 수 있으므로 이에 대한 체계적인 검토로 사전 예방적인 소비자정책과 사후구제의 소비자정책 모두 새롭게 정립해 두어야 한다. 사전예방적인 소비자정책으로는 (1) 위해방지, (2) 규격의 적정화, (3) 거래의 적정화, (4) 표시광고의 적정화, (5)소비자정보제공의 충실화 및 소비자능력의 향상을 위한 소비자교육의 강화, (6) 개인정보보호의 강화가 필요하다. 사후구제의 소비자정책으로는 (1) 소비자분쟁해결기준의 정비, (2) 피해구제 관련 법률의 제정이나 개정 등이 필요하다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.6
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• pp.225-236
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• 2003

In this paper, we propose a wireless scheduling algorithm to provide the Internet delay proportional differentiated services in wireless networks. For considering network environments that have burst and location-dependent channel errors, our proposed WDPS(Wireless Delay Proportional Service) scheduling algorithm adaptively serves packets in class queues based on the delivered delay performance for each class. The remarkable characteristics of WDPS scheduler are supporting a fair relative delay service, providing graceful throughput and delay compensation, and avoiding class queue blocking problem. Through simulations, we show that the algorithm achieves the desirable properties to provide delay proportional services in wireless networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7A
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• pp.629-634
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• 2002

The next generation of wireless communication system is expected to provide users with wireless multimedia services such as high speed internet access and wireless mobile computing. Depending on the Quality of Service(QoS) requirements and different applications per user, many wireless communication systems have been proposed. The simple decoding algorithm of space-time block coding is based on the assumption of flat fading channel, where no intersymbol interference exists. In this paper, we propose to combine space-time transmit diversity with adaptive equalizer. The proposed system effectively eliminates interference caused by multipath environment. Simulation results show that the proposed system provides improved bit error rate performance.

• The KIPS Transactions:PartC
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• v.12C no.2 s.98
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• pp.175-182
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• 2005

This paper presents encryption techniques for digital right management solutions of MPEG-4 streams. MPEG-4 is a format for multimedia streaming and stored in the MPEG-4 file format. We designed three kinds of encryption methods, which encrypt macro blocks (MBs) or motion vectors (MVs) of I-, P-VOPs (Video Object Planes), extracted from the MPEG-4 file format. We used DES to encrypt MPEG-4 data Based on theses three methods, we designed and implemented a DRM solution for an Internet broadcasting service, which enabled a MPEG-4 data streaming, and then compared the results of decryption speed and quality of rendered video sequences to get an optimal encryption method.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.4
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• pp.425-430
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• 2022

This study was designed to verify the shelf-life of a freeze dried-block type of convenience food for rockfish Sebastes schlegeli seaweed soup product stored at different storing temperatures (25, 35, and 45℃) for 5 months. The polyunsaturated:saturated fatty acid ratio of the product stored at 25℃ was higher than that of products stored at 35℃ and 45℃ for 5 months. The colorimetric assessment indicated a noticeable decrease in the brightness of product color after 5months of storage at 35℃ and 45℃. Increased storage temperature and time negatively affected the product color. The products stored at 35℃ and/or 45℃ for more than 3 months tended to be more yellowish-red in color than those stored at 25℃ for shorter periods. No disease-causing microorganisms, including Escherichia coli and Staphylococcus aureus, posing health hazards to the human, were detected on food safety evaluation, regardless of storage conditions. Based on food visual shelf life simulator the shelf life of the rockfish seaweed soup was estimated approximately 22 months, considering the data from yellowness the safety factor of 0.7.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.613-616
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• 2010

본 논문에서는 새로운 움직임 추정(motion estimation, ME) 방식을 사용한 프레임 비율 변환(frame rate conversion, FRC) 기법에 대해 제안한다. 기존의 프레임 비율 변환을 위한 움직임 추정 방식은 영상 압축에서 사용되고 있는 SAD를 사용하여 블록(block) 단위로 움직임 벡터를 추정하는 방식에 기초를 두고 있다. 그러나 잔여 신호(residual signal)를 저장하는 영상 압축과 달리, 잘못된 움직임 추정은 합성된 출력 영상에서 심각한 품질 저하를 가져올 수 있다. 이를 보완하기 위해 움직임 개선(motion refinement, MR)이 사용되고 있지만, 근본적인 해결을 위해서는 정확한 움직임 추정 알고리즘 사용이 필요하다. 특히 SAD를 통한 움직임 추정은 고르지 못한 움직임 벡터장(motion vector field, MVF)을 형성할 수 있으며, 종래의 연구에서 이를 해결하기 위해 SAD(sum of absolute difference)에 벡터의 공간제약(spatial constraint) 항목을 추가하여 비교적 고른 움직임 벡터장을 형성하는 방식이 제시되었다. SAD와 공간 제약 항목의 반영 비율에 따라 움직임 벡터의 중요성과 움직임 벡터장의 일관성이 서로 상충하는데, 기존의 방식은 이 비율을 일정한 상수(constant)값을 사용하고 있으며, 이러한 방식은 이미지의 특성에 따라 결과가 달라진다. 본 논문에서는 SAD와 공간 제약 항목 사이의 반영 비율을 이미지의 특성에 적응하는 방식을 사용하는 움직임 예측을 제시하고, 수행한 결과를 기존의 방식에 의한 결과와 비교하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.507-507
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• 2022

작물 재배에서 정밀 관개 및 물관리를 위해 토양수분 모니터링이 필수적이며, 최근 이상기후에 따른 가뭄 빈도가 증가함에 따라 토양수분 변동에 따른 적절한 대응이 필요한 실정이다. 특히, 국산밀 생장기의 토양수분 및 관개는 생산성에 중요한 영향을 미치고 있으나, 빈번한 봄가뭄의 영향으로 작물 생산 및 품질 관리의 어려움을 겪고 있다. 따라서 국산밀의 안정적 생산을 위한 토양수분 및 양분 관리에 대한 연구가 필요하다. 본 연구에서는 ICT 기반의 토양 층위별 모니터링 시스템을 구축하여 물관리에 따른 국산밀의 안정적 생산성을 분석하고자 한다. 대상지역은 전라북도 남원시 운봉읍에 위치한 국립식량과학원 운봉시험지이며, 시험포장은 수분처리 조건에 따라 총 4개(A: 한발조건, B: 적정수분, C: 무처리) 처리구로 3개 블록을 구분하여 4반복으로 구성하였다. ICT 기반 10개 토양수분 및 EC (Electrical conductivity) 관측 장비를 통해 실시간으로 자료 수집하였으며, 밀 생육조사는 생육단계별 초장, LAI, 지상부 및 지중 생체중 등 자료를 수집하였다. 수집된 자료는 처리구별 물관리에 따른 토양수분과 생육지표의 상관관계 분석을 통해 가뭄에 따른 생육 영향과 적정 관개용수의 공급시기 및 공급량을 분석하였다. 본 연구는 밀 생장기의 봄가뭄에 대응하기 위한 물관리 기초자료로 활용하고자 하며, ICT 기반의 스마트관리 플랫폼을 개발하여 밀 작황 진단 및 예측을 통해 국산밀의 안정적 생산성에 기여하고자 한다.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.05a
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• pp.35-81
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• 1998

Distinct Element Method(DEM) has a great advantage to model the discontinuous behaviour of jointed rock masses such as rotation, sliding, and separation of rock blocks. Geometrical data of joints by a field monitoring is not enough to model the jointed rock mass though the results of DE analysis for the jointed rock mass is most sensitive to the distributional properties of joints. Also, it is important to use a properly joint law in evaluating the stability of a jointed rock mass because the joint is considered as the contact between blocks in DEM. In this study, a stochastic modelling technique is developed and the dilatant rock joint is numerically modelled in order to consider th geometrical and mechanical properties of joints in DE analysis. The stochastic modelling technique provides a assemblage of rock blocks by reproducing the joint distribution from insufficient joint data. Numerical Modelling of joint dilatancy in a edge-edge contact of DEM enable to consider not only mechanical properties but also various boundary conditions of joint. Preprocess Procedure for a stochastic DE model is composed of a statistical process of raw data of joints, a joint generation, and a block boundary generation. This stochastic DE model is used to analyze the effect of deviations of geometrical joint parameters on .the behaviour of jointed rock masses. This modelling method may be one tool for the consistency of DE analysis because it keeps the objectivity of the numerical model. In the joint constitutive law with a dilatancy, the normal and shear behaviour of a joint are fully coupled due to dilatation. It is easy to quantify the input Parameters used in the joint law from laboratory tests. The boundary effect on the behaviour of a joint is verified from shear tests under CNL and CNS using the numerical model of a single joint. The numerical model developed is applied to jointed rock masses to evaluate the effect of joint dilation on tunnel stability.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.215-225
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• 2011

In general, the precast columns can obtain its homogeneous quality as they are produced in a factory with a hollow concrete block type by using high strength concrete, so that they can generate the reduction of dead load. Such a method of precast hollow concrete columns is already implemented in USA and Japan and used for connecting between blocks which use PC tendons. However, it is inevitable to have uneconomical construction with excessive cost in early stage when PC tendons are used. This study aims to develop an economical precast column with high quality and constructability which consists of only splice sleeve and general reinforcing bar without using PC tendons in order to reduce the construction period and cost. To achieve this goal, this study tested the performance of total 5 minimized models in the experiment with the variables such as hollowness, diameter of main reinforcement bar and cross-sectional size for the cross section of precast column by using grouting type splice sleeve which is a new type joint rebar. And it also verified the performance of column in the experiment for a large-sized model in order to overview its applicability by excluding large scale effect.