• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.712-714
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• 2014

스카이라인 계산은 사용자에게 의미 있는 정보를 추천하기 위해 많이 사용되고 있다. 일반적으로 스카이라인은 대용량 데이터 집합을 대상으로 하기 때문에 사전에 계산해 놓고 사용한다. 그러나 사용자가 이동하는 경우에는 이와 같이 계산해 놓은 스카이라인이 사용자의 위치 조건을 반영한 것이 아니므로 부적절할 수 있다. 본 연구에서는 사용자가 이동하는 조건을 고려하여 사용자에게 실시간으로 최적화된 스카이라인을 지속적으로 제공하는 기법을 제안한다. 제안한 기법은 실험을 통해 그 효율성을 검증하였다.

• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.270-277
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• 1998

As the network technologies advance, the control systems progress from a centralized architecture to a distributed one. However, these control systems were designed mostly based on the general-purpose operating systems(OS) and have many problems for assurance of a real-time property required for plant processing fields. Therefore, the control systems far a plant process upon real-time OS hare been increased gradually. In this paper, the real-time OS emphasizes on the realization of real-time processing capability, reliability of real-time response, and multi-processing functionality which are prerequisites for a distributed control system. And on the basis of this OS, the number of executable loop and logic, the functions of main plant processing, was analyzed and its validity was also evaluated. The system in this paper was designed not to effect on processing data while online, and the time spent on switching was measured.

• Journal of KIISE:Information Networking
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• v.29 no.3
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• pp.277-285
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• 2002

This paper proposes and analyzes an error control scheme for the transmission control based real-time communication, such as FDDI, TDMA, and wireless LAN, which delivers the message according to the round robin fashion after the off-line bandwidth allocation. Taking into account the time constraint of each message, the proposed error control scheme makes the receiver transmit the error report via asynchronous traffic while the sender resend the requested message via overallocated access time which is inevitably introduced by the bandwidth allocation procedure for hard real -time guarantee. The error control procedure does not interfere other real -time message transmissions. In addition, as each frame contains the size of the message it belongs, the receiver can recognize the end of completion of message transmission. This enables earlier error report to the receiver so that the sender can cope with more network errors. The analysis results along with simulation performed via SMPL show that the proposed scheme is able to enhance the deadline meet ratio of messages by overcoming the network errors. Using the proposed error control scheme, the hard real -time network can be built at cost lower than, but performance comparable to the expensive dual link network.

• Journal of the Korea Society for Simulation
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• v.26 no.3
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• pp.13-22
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• 2017

This research proposes and applies a pipelining parallel processing technique to enhance the speed of visualizing the results of real-time simulations. Generally, a simulation with real-time visualization consists of three processes: executing a simulation model, transmitting simulation result, and visualizing simulation result. If we have these processes in serial, the latency from simulation to visualization will be very long, which degrades the speed of visualization of data from real-time simulation. Thus, the main purpose of this research is maximizing performance by adapting pipelining parallel processing technique to the real-time simulation visualization. Also we show that performance is improved by adding multi-threading technique to each process. This paper proposes a theoretical performance model and simulation results of the techniques and then we applied this to an air combat simulation model as a case study. As the result, it shows that the performance is greatly enhanced than the original model's execution time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.5
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• pp.326-334
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• 2019

Development of Small UAV using HILS (Hardware In the Loop Simulation) can be effectively used to improve the reliability of UAV (Unmanned Aerial Vehicle) while reducing cost and time. It is also possible to reduce the damage to people or property by simulating the malfunction of the Flight Control Computer (FCC) that may occur during the actual flight. For applying such HILS, a real-time simulation environment capable of providing an environment similar to an actual flight condition is required. In this paper, we constructed a real - time HILS environment for Small UAV using 6 D.O.F motion table. In order to link the 6 D.O.F motion table developed in the previous research with the HILS environment in real time, the motion algorithm was changed from the position control method to the velocity control method. Also, we implemented modeling of inverse kinematics model for command transmission in Matlab $Simulink^{(R)}$ and verified the action of motion table according to the simulation model.

• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.37-44
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• 2009

In this paper, we propose an efficient method which improves the performance of transmission of PGA which is essential data for real-time earthquake monitoring system. Currently, above 120 earthquake stations were installed nationwide and additional installation is expected because the social interesting of earthquake hazard is rising. Real-time earthquake monitoring system checks earthquake occurrence by using PGA were calculated from acceleration data of each seismic station. An efficient method of PGA data transmission is key factor of real-time monitoring. The key idea of proposed method is to deal with each seismic station using an unique ID, to assign one bit to indicate whether a packet include a station's data or not. Proposed method can contain more station data and decrease the data loss compared to current method. To verify proposed method, we investigate the turnaround time and ratio of data loss using above 91000 packets. As results of experiment. the proposed method is proven that the method need more time about 50% but reduce the data loss about 87% as compared to previous method.

• Smart Media Journal
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• v.12 no.11
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• pp.145-153
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• 2023

In a P2P-based distributed storage system where peers frequently join and leave, it is essential to guarantee not only data availability but also playback quality comparable to that provided by local storage devices when playing back video files with real-time constraints. In addition, cloud storage services based on distributed storage systems provide each user with the functionality to share their files with other users, so when multiple users request playback of the same video file at the same time, all playback should be supported seamlessly in real time. Therefore, in this paper, we propose a scheme that process multiple simultaneous playback requests for each video file in real time as well as data availability in a P2P-based distributed storage system that supports file sharing. This scheme can support real-time simultaneous playback and efficiently use storage space by adjusting the amount of redundant data encoded through erasure coding according to the number of concurrent playback requests for each video file.

• Proceedings of the Korea Water Resources Association Conference
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• 1991.07a
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• pp.88-101
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• 1991

충주댐 및 소양강댐 유역에 대해 현재 한국수자원공사에서 개발 사용되고 있는 저류함수 유출모형에 최적화 기법을 적용하여 모형을 효율적으로 자동보정 하기위함이 본 연구의 목적이다. 최적화 기법으로는 다양한 조건하에서도 해의 안정성이 Gradient-Based 방법보다 우수한 직접 탐색법(Direct Search Method)의 하나인 Pattern-Search법으로 선정하였으며 목적함수로는 산정된 유출과 관측치의 편차의 제곱에 대한 누계치로 정의하였다. 합성유입량(Synthetic Inflow)을 이용한 민감도 분석에 의해 매개변수 5개(유역 저류상수 및 지체시간, 포화우량, 하도의 지체시간)를 결정변수로 선정하였다. 또한 실시간 모형의 보정을 위하여 최적화 모형의 수렴조건을 분석한 결과 P-S 법의 증분 감소횟수 2회가 합리적으로 나타났다. 본 모형을 충주댐 및 소양강댐의 과거 홍수사상에 대해 적용하였으며 댐지점에서 전체유역을 일괄 보정하는 방법과 댐 상류 수위국을 기준으로 나눈 중유역별로 일괄 보정하는 방법을 채택하여 분석하였다. 실시간 보정된 모형의 예측기능을 시험한 결과 상당한 오차발생의 여지가 충분하며 중유역별 매개변수의 보정은 대유역 일괄보정에 비해 예측에 따른 오차를 줄일 수 있는 방법의 하나이다. 또한 최적화 기법에 의한 매개변수의 자동 보정은 시행착오에 의한 수동보정의 경우보다 시간 및 노력면에서 효율적이며 보다 신뢰성 있는 보정을 실시 할 수 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.419-422
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• 2005

본 논문은 미지의 공간 그래프에 대한 실시간 최단 경로 탐색 알고리즘인 $RTA{\ast}$ 알고리즘과 $PHA{\ast}$ 알고리즘을 소개하고, 예제 그래프를 통해 이들의 특성을 설명한다. 또 3차원 온라인 게임 환경인 언리얼 토너먼트(Unreal Tournament) 게임과 Gamebots 시스템을 이용하여 두 알고리즘 간의 탐색 최적성과 효율성을 비교하였다. 이 실험을 통하여 $PHA{\ast}$ 알고리즘은 언제나 최선의 경로를 탐색하지만 이동경로가 많고, 시간이 많이 걸릴 수 있으며, $RTA{\ast}$는 최적의 경로 혹은 차선 경로를 빠른 시간 내에 탐색함을 확인 하였다. 따라서 이러한 특성을 바탕으로 주어진 탐색 환경의 조건에 따라 두 알고리즘을 선택적으로 적용함으로써 보다 높은 효과를 얻을 수 것으로 기대한다.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2006.06a
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• pp.47-51
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• 2006

본 실험은 한국어 심성어휘집의 표상 정보가 음운정보로 이루어져 있는지, 철자정보로 이루어져 있는지 알아보기 위해 실시되었다. 실험자극은 한국어의 2음절 단어 중 음운변화(자음동화)를 겪는 단어(예: 국민)를 사용하였으며, 각 조건은 철자이웃이 크며 음운 이웃이 큰 단어 조건(O+P+), 철자이웃이 크고 음운이웃은 작은 단어 조건(O+P-), 철자이웃은 작고 음운이웃이 큰 단어 조건(O-P+), 철자이웃과 음운이웃 모두가 작은 조건(O-P-)이었다 실험 1에서 어휘판단 과제를 실시한 결과, 음운이웃 크기와 철자이웃 크기간의 상호작용이 나타났다. 실험2는 동일한 실험자극을 사용한 fMRI 연구를 수행하였다. 실험2 결과 음운처리에 관련된 뇌영역의 활성화가 나타났다. 본 연구결과는 한국어의 경우 심성어휘집이 음운정보로 이루어져 있음을 시사한다.