• 융합신호처리학회논문지
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• 제3권3호
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• pp.14-20
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• 2002

본 논문에서는 현재의 인터넷 환경하에서 클라이언트가 가진 대역폭을 최대한 활용하여 최선의 서비스를 제공할 수 있는 웨이브릿 기반에서 SPIHT(set partitioning in hierarchical trees)를 이용한 비디오 데이터의 압축과 멀티스트림을 이용한 전송 기법을 제안한다. 실험 결과, 제안한 방법은 웨이브릿 기반 비디오 부호화기를 이용하였기 때문에 동일한 비트율에서 기존의 DCT(discrete consine transform) 기반 비디오 부호화보다 블록킹 현상이 없이 화질이 약 1.5dB가 상승하였으며, 점진적 전송이 가능하였다. 그리고, 고압축시 발생하는 에러 전파를 막기 위해 TCP(transmission control protocol)상에서 효율적인 전송과 네트워크의 지터에 강하며 클라이언트가 가진 대역폭을 최대한 활용할 수 있는 멀티스트림 전송을 통해 그 효용성을 확인하였다.

• 한국산업정보학회논문지
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• 제12권1호
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• pp.54-60
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• 2007

The Digital Multimedia Broadcasting(DMB) system is developed to offer high quality multimedia content to the mobile environment. The system adopts the MPEG-4 standard for the main video, audio and other media format. For providing interactive contents, it also adopts the MPEG-4 scene description that refers to the spatio-temporal specifications and behaviors of individual objects. With more interactive contents, the scene description also needs higher bitrate. However, the bandwidth for allocating meta data, such as scene description is restrictive in the mobile environment. On one hand, the DMB terminal renders each media stream according to the scene description. Thus the binary format for scene(BIFS) stream corresponding to the scene description should be decoded and parsed in advance when presenting media data. With this reasoning, the transmission delay of the BIFS stream would cause the delay in transmitting whole audio-visual scene presentations, although the audio or video streams are encoded in very low bitrate. This paper presents the effective optimization technique in adapting the BIFS stream into the expected bitrate without any waste in bandwidth and avoiding transmission delays inthe initial scene description for interactive DMB content.

• 한국물환경학회지
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• 제29권2호
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• pp.212-222
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• 2013

A watershed model was constructed using Hydrological Simulation Program Fortran to quantitatively predict the stream flows at major tributaries of Nakdong River basin, Korea. The entire basin was divided into 32 segments to effectively account for spatial variations in meteorological data and land segment parameter values of each tributary. The model was calibrated at ten tributaries including main stream of the river for a three-year period (2008 to 2010). The deviation values (Dv) of runoff volumes for operational stream flow forecasting for a six month period (2012.1.2 to 2012.6.29) at the ten tributaries ranged from -38.1 to 23.6%, which is on average 7.8% higher than those of runoff volumes for model calibration (-12.5 to 8.2%). The increased prediction errors were mainly from the uncertainties of numerical weather prediction modeling; nevertheless the stream flow forecasting results presented in this study were in a good agreement with the measured data.

• 한국정보통신학회논문지
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• 제9권1호
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• pp.76-87
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• 2005

본 논문에서는 무선을 포함한 패킷 전송에서의 효율성을 위해 차세대 전송 계층 프로토콜인 SCTP에 ROHC(RObust Header Compression)을 적용한 ROHC 프로파인 7(ROHC-SCTP)을 제안한다. 제안된 ROHC-SCTP는 SNR(Sequence Number ROHC)-SCTP의 1 또는 2 바이트 길이의 새로운 필드를 SCTP 패킷 헤더에 추가하여, SCTP 멀티 스트림을 acknowledgement 스트림과 data 스트림으로 나누어 헤더 압축을 하며, 동기화 손실이 발생한 경우 context를 복구하는데 사용될 수 있도록 설계되었다. ROHC-SCTP의 제안을 통해 SCTP 헤더의 오버헤드 율을 최대 25%까지 감소할 수 있으며 대역폭 또한 최대 5% 정도 절약할 수 있다.

• 한국농공학회논문집
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• 제49권6호
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• pp.11-20
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• 2007

In order to make the way to determine the instream flow more practically, we have investigated many case studies and reviewed reports and papers. To validate instream flow level suggested by the case studies, DAWAST and HEC-RAS model were applied to the Gap-stream watershed in Daejeon city. Flow-duration analysis was performed both with the stream flow data gauged in the Indong, Boksu, and Hoeduck stations, and with the stream flow data estimated by the DAWAST model and the specific discharge method. Instream flow was determined among the flow-duration analysis, DAWAST, HEC-RAS model and mass balance approach. It was satisfied with various factors such as target water quality, water depth for eco-system and resorts, water surface width, flow velocity for landscape in dry season. The study suggested that the mean low flow could be replaced into the instream flow for the preliminary study because the instream flow considering ecosystem, landscape, water-friendly environment and water quality was generally close to the mean low flow.

• 상하수도학회지
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• 제20권4호
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• pp.573-584
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• 2006

This study was carried out to investigate the causes of fish kills in the Yudeung Stream in Daejeon, Korea using literature reviews, governmental and our water quality monitoring data of the study site, rainfall data, intensive water quality monitoring during rainfall events, sediment pollutant contents and laboratory bioassay tests. Fish kill in urban streams can be caused by combined effect of reduction in dissolved oxygen concentration, increase in toxic material or increase in turbidity in waterbody due to introduction of surface runoff or effluent of combined sewer overflows after rainfall from the watershed areas. Despite of extensive and intensive field surveys and laboratory tests, it was found that those conventional methods have limitations to identify causes of fish kills in urban streams. It would be necessary to use dynamic water quality modeling to predetermine the range and level of water pollution in the stream and automatic water quality monitoring system that can collect water samples and detect water quality continuously.

• 상하수도학회지
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• 제27권5호
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• pp.661-669
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• 2013

River-water quality has been greatly improved during past several decades with the extraordinary expansion for the wastewater treatment capacities by the government. Research aims to select the priority restoration streams based on the chronicle data for tributaries in Geumgang watershed as the main stream area in the Chungchungnamdo province. The quality of BOD, phosphorus and percent of sewered population on 15 branch streams were compared by the grouping methods. The results of group D streams by category I that exceed 3.0 mg/L for BOD and 0.1 mg/L for phosphorus were Seuksung, Ganggyung and Bangchuk stream. The results of group D streams by category II that exceed 3.0 mg/L for BOD and less than 63.5 % of average percent of sewered population were Ganggyung, Gilsan, Bangchuk and Seuksung stream. The final results of selected streams drawn by the chronicle data which exceeded the standard quality and lower than the average percent of sewered population were Seoksung, Gangeyung and Bangchuk stream. The pollution of rivers in the down streams were more serious than in the upper streams. Their watersheds have to be improved river water quality, especially to extend sewer systems as well as wastewater treatment facilities.

• 정보보호학회논문지
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• 제32권2호
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• pp.439-446
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• 2022

웹사이트나 메일의 첨부 파일을 이용해 문서형 악성코드의 유포가 활발하게 이루어지고 있다. 문서형 악성코드는 실행 파일이 직접 실행되는 것이 아니므로 보안 프로그램의 우회가 비교적 쉽다. 따라서 문서형 악성코드는 사전에 탐지하고 예방해야 한다. 이를 탐지하기 위해 문서의 구조를 파악하고 악성으로 의심되는 키워드를 선정하였다. 문서 내의 스트림 데이터를 아스키코드값으로 변환하여 데이터셋을 만들었다. CNN 알고리즘을 이용하여 문서의 스트림 데이터 내에 존재하는 악성 키워드의 위치를 확인하고 인접 정보를 활용하여 이를 악성으로 분류했다. 파일 내의 스트림 단위로 악성코드를 탐지한 결과 0.97의 정확도를 보였고, 파일 단위로 악성코드를 탐지한 결과 0.92의 정확도를 보였다.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2163-2173
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• 2024

This study introduces a transient analysis module developed for RAST-V and validates it using the Kalinin-3 benchmark problem. For the benchmark analysis, RAST-V standalone and STREAM/RAST-V calculations were performed. STREAM supplies the few-group constants and RAST-V conducts a 3D core simulation utilizing few-group cross-sectional data. To improve accuracy, the main solver was developed based on the advanced semi-analytic nodal method. To evaluate the computational capability of the transient analysis module in RAST-V, Kalinin-3 benchmark is employed. Kalinin-3 represents a coolant transient benchmark that offers experimental data during the deactivation of the Main Circulation Pumps. Consequently, the transient calculations reflected the changes in the reactor flow rate. Benchmark comprising steady-state and transient calculations. During the steady state, the STREAM/RAST-V combination demonstrated a 30 ppm root mean square difference from 0 to 128.50 EFPD. For the transient calculations, STREAM/RAST-V showed power differences within ±7 % over a range of 0-300 s. Axial offset differences were within ±3 %, and the RMS difference in radial power ranged within 2.596 % at both 0 and 300 s. Overall, this study effectively demonstrated the newly developed transient solver in RAST-V and validated it using the Kalinin-3 benchmark problem.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.63-69
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• 1999

The purpose of this study is to develop Water Quality Management System(WQMS), which performs calculating pollutant discharge and forecasting water quality with water pollution model. Operational water quality management requires not only controlling pollutants but acquiring and managing exact information. A GIS software, ArcView was used to enter or edit geographic data and attribute data, and MapObject was used to customize the user interface. PCI, a remote sensing software, was used for deriving land cover classification from 20 m resolution SPOT data by image processing. WQMS has two subsystems, Database Subsystem and Modelling subsystem. Database subsystem consisted of watershed data from digital map, remote sensing data, government reports, census data and so on. Modelling subsystem consisted of NSPLM(NonStorm Pollutant Load Model)-SPLM(Storm Pollutant Load Model). It calculates the amount of pollutant and predicts water quality. This two subsystem was connected through graphic display module. This system has been calibrated and verified by applying to Mokhyun stream watershed.