• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.237-240
• /
• 2010

AIS(Automatic Identification System)는 선박과 육상 및 선박 상호간에 선박의 항행관련 정보를 상호 교환함으로써 안전항해를 제고하기 위하여 도입된 무선설비로서 그 활용도가 매우 높아지고 있으며 AIS 탑재 선박도 증가하고 있다. 그러나 AIS에서 사용하고 있는 초단파의 전파 특성으로 인하여 비교적 근거리 통신만 가능하고 장거리 선박추적 관리를 위한 용도로 활용하는 데는 어려움이 있었다. 이러한 통신권의 한계를 극복하기 위한 방안으로 저궤도 위성을 사용하는 위성 AIS의 도입에 대한 연구가 주요 선진국을 중심으로 추진되고 있으며, 성능을 제고하기 위한 기술 기준 연구도 진행되고 있다. 본 연구에서는 저궤도 위성을 사용한 AIS의 문제점인 메시지 수신확률을 분석하기 위하여 현재 사용 중인 지상파 AIS의 특성 및 저궤도 위성 AIS의 문제점을 분석하고 메시지 수신확률에 대한 시뮬레이션을 수행하여 그 결과를 분석하였다. 분석결과 위성 AIS는 지상파 AIS에 비하여 통신권이 크게 확대되는 반면 채널 용량의 한계 및 채널간 간섭으로 인하여 AIS 메시지 충돌이 심하게 발생하고 메시지 수신 확률이 매우 낮음을 알 수 있었다. 따라서 현재의 지상파 AIS 표준을 적용한 위성 AIS의 실시간 정보 교환은 사실상 불가능하며 위성 AIS의 메시지 수신 확률을 제고하기 위해서는 위성 AIS를 위한 별도의 표준을 제정할 필요가 있음을 알 수 있다.

• Journal of Korea Game Society
• /
• v.14 no.4
• /
• pp.45-52
• /
• 2014

We cannot load the entire data for high-resolution terrain model to the GPU memory since its size is too big. Out-of-core approaches are commonly used to solve the problem. However, due to limited bandwidth of the secondary storage, it is difficult to render the terrain in real-time. A method that compresses the DEM data with wavelet transform on GPU, and renders the decoded data is suggested. However, it is inefficient since it has to sample the values from textures, convert them to vertices, and generate a mesh periodically. We propose a method to store the approximation coefficients of wavelet compression as vertex attributes and render the terrain by decoding the data on geometric shader. It can reduce the amount of transferring terrain texture since approximation coefficients are given as an attribute of the vertex. Also, it generate meshes without additional upload of terrain texture.

• The Journal of the Korea Contents Association
• /
• v.7 no.6
• /
• pp.69-78
• /
• 2007

In recent years, embedded mobile systems have been expanding their application domains from embedded portable devices which only execute a specialized application such as MP3 player or digital camcoder to digital convergence devices which execute more complicated applications converged various functionalities such as video and audio play, digital dictionary, DMB, games, phone, etc. As it requires the increasing hardware performance such as more faster CPU and more larger RAM, display, disk size, it has brought about a corresponding increase in power consumption. However, coupled with relatively small gains in battery capacity over recent years, the importance of software architecture including intelligent power management has become paramount. In this paper, we have ported UbiFOSTM with energy saving techniques on the ARM9-based MBA2440 platform. For energy savings, we adapted the dynamic power management and the device power management schemes based on monitoring workload. Experimental results with some well-known applications show that proposed low power technique could save energy up to 24 %.

• Korean Journal of Plant Resources
• /
• v.15 no.3
• /
• pp.243-249
• /
• 2002

This experiment was conducted to find out the effects of livestock excrements application on the growth and yield of leaf, stem and seed in Agrimonia pilosa Ledeb. the results were summarized as follow. In the soil after experiment, P2O5 and K contents were high in order of cattle droping 〈 pig droping 〈 chicken droping treatment. The plant height was increased cattle dropping〈 pig dropping〈 chicken dropping treatment plot. Number of stems was inclined to increase in the plot of 2,000 kg/10a application of chicken dropping and cattle dropping. Number of leaves was also increased 21.8∼51.6% by application 3,000 kg/10a of chicken and cattle dropping, and application 2,000 kg/10a of pig dropping, respectively. Dry weight of aerial part was high in order of 1,000〈 3,000〈 2,000 kg/10a〉control, on occasion 2,000 kg/10a treated, that was highest in the application of chicken dropping. Yield of seeds was also increased to 61％ and 86% at the 2,000 kg/10a plot of pig and chicken dropping, respectively. While yield of seeds was increased 50％ at the 3,000 kg/10a application of cattle dropping. Flowering ratio was 49.1％ in control, 55.6, 58.9 and 68.3% in cattle, pig and chicken dropping with 2,000 kg/10a, respectively, on June 22. Flowering ratio was the highest in the plot of chicken dropping with 2,000 kg/10a.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.13 no.3
• /
• pp.64-72
• /
• 1999

The fictitious power theory in time domain is very easy to understand, but power analyzing speed of active power is increased, because power is analyzed using signal tedmiques based on the corre1ation between voltage and current wavefonns. Also, conventional methods in time/frequency domain to evaluate the correlation performance of active power filters are not provided easy solutions. So, the authors have previously proposed 3-D current coordinates which is composed into active component, fundarrental reactive component and distorted component of nonlinear loads current. This trethod has excellent perfonnance, but can not evaluate the characteristics of nonlinear load current whether It is inductive or capacitive. Therefore, To overcorre problems trentioned previously, this paper deals with the simple average power theory and the modified 3-D current coordinates for evaluating the compensation perfonnance of active power filters. To confirm the validity, active power filter simulator is developed using C-language. From the simulation, results are discussed their utility.tility.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.9 no.3
• /
• pp.30-40
• /
• 2010

The freeway congestion is largely generated by a mainline spillover of the exit ramp queue. So it is necessary to study for modeling of the phenomenon and applying the model. In this study, the authors evaluated applicability of the Supply-Demand model, which can express traffic flow for the freeway by applying flexibly supply and demand curves for capacity of the freeway. First the authors proposed methods processing input data required in the Supply-Demand model, such as sending & receiving functions and time-varying capacity constraints for the freeway mainline. After modeling the Supply-Demand application model, the authors applied the model to the site including congested Hongeun exit ramp in Seoul Ring-road, and improved the model by adjusting application techniques and calibrating parameters. The result of the analysis showed that the Supply-Demand model yielded a queuing pattern and queue location similar to them observed in the field data, and applicability of the Supply-Demand model was varified.

• Geophysics and Geophysical Exploration
• /
• v.1 no.1
• /
• pp.71-78
• /
• 1998

Inversion schemes of 2-D MT survey data generally take enormous computational time and computer memory. In addition, careful attention must be paid in handling MT data, especially in cases of TM mode, inversion results can be seriously distorted because of static effect caused by current channeling across inhomogeneous surface boundaries. There-fore inversion algorithm using the GRRI scheme for TM mode MT data was implemented. This scheme is based on a perturbation analysis with a locally 2-D analysis and local inversions were sequently performed over each divided section without additional forward modelings. The algorithm was applied to several synthetic data for the purpose of verification of its efficiency and applicability. With less computer resources than conventional schemes, it could handle static effect directly by including current channeling across inhomogeneous boundaries. Thus it is expected to be used for an useful tool such as a real-time inversion scheme in the field.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.105-105
• /
• 2022

섬진강댐은 100년빈도 홍수에 대응토록 설계되어 홍수조절 능력이 타 다목적댐 대비 상대적으로 취약함에 따라 댐운영 체계 개선이 필요하다. 이에따라 K-water는 홍수시 피해를 최소화 할 수 있도록 댐운영과 관련한 홍수대응 체계를 개선하였다. 주요 개선대책은 섬진강 홍수조절용량 추가확보, 홍수기 강우특성을 고려한 홍수조절, 하류주민 및 기관과 소통에 기반한 정보 공유체계 확립, 디지털 트윈 기반 댐 운영 의사결정시스템 구축이다. 섬진강댐의 건설홍수조절용량은 3천만m³으로, 타 다목적댐 설계빈도인 200년 대비 홍수대응 능력이 미흡하다. 이에따라, 섬진강댐은 '21.1월부터 '22.12월까지 홍수기 제한수위를 기존 197.7m에서 2.5m 낮춘 194.0m로 시범운영하고 있다. 이를통해 기존 3천만m³에서 9천만m³까지 6천만m³의 홍수조절용량을 추가 확보하였다. 이와 연계하여 홍수기 동안 섬진강댐 운영수위 기준을 별도 수립하여 홍수기 전·후반으로 나누었으며, 전반기(~7/31)는 '20년 홍수상황에서 발생한 더블피크 집중호우(360mm)에 대응가능한 홍수조절능력을 확보하고, 후반기(8/1~)는 홍수조절능력을 최대한 확보함과 동시에 차년도 용수공급을 대비할 수 있도록 운영수위를 개선하였다. 그간 수문방류 정보는 '댐 관리규정'에 따라 방류개시 3시간 전까지 방류계획을 하류지역의 지자체 및 주민에게 통보하였으나, 하류주민들이 충분히 사전준비하기에 시간적으로 부족하다는 의견을 제시함에 따라 수문방류 24시간전 사전 안내토록 '수문방류 예고제'를 도입, 시행하였다. '댐 홍수관리 소통회의'를 통해 댐 운영기관-정부기관-주민이 댐 운영에 대한 전반에 대해 함께 공유하고 운영 제약사항 및 개선사항을 공동 발굴하여 대책을 마련하는 체계를 구축하였다. 댐 운영 개선사항과 더불어 댐방류 의사결정시, 실시간 하류하천 상황에 대한 확인이 어려움에 따라, 3D기반 의사결정 지원시스템인 Digita Twin Platform을 개발 및 구축하여 '22년부터 섬진강댐 운영에 시범적용을 추진하고자 한다.

• Spatial Information Research
• /
• v.14 no.4 s.39
• /
• pp.379-389
• /
• 2006

Map databases for CNS (Car Navigation System) can be accessed quickly and compressed efficiently due to that these are usually recorded as in a PSF (Physical Storage Format). However, it is difficult to create and manage data storage based on a file-system. To solve these problems, DBMS needs to be combined with spatial data management. Therefore, we developed an embedded DBMS with which to store data and conduct quick searches in CNS. Spatial data could be easily managed and accessed using the compression method, Multi-Link, spatial index, and spatial division. In the result, the proposed embedded DBMS searched quickly and stably supported data management. If synchronization is applied in DBMS, it is expected to utilize the advantages of an embedded DBMS.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.5
• /
• pp.1525-1534
• /
• 2014

In recent years, the passengers are likely to decide their route on impulse due to the development of the integrated public transport system, and real-time information system. Especially, public transport fare integration in Seoul Metropolitan area, 2004 makes them not to have resistance about changing the modes or routes and their route choice is most effected by the degree of congestion. Assignment model have limitations to describe route changes by congestion. In this study, the concept of a link cost function used in road assignment and Effective frequency is introduced to describe the passengers' behavior when the capacity of public transport is over and the waiting time variation. Two situations, new transit line operation and accident, are set up to validate the model, as a result of the transit assignment by this model, the traffic on networks is not over the capacity. It is expected that this study will be of help to reflect the various behaviors in transit assignments.