• 오토저널
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• 제5권2호
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• pp.41-47
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• 1983

The analysis shows that the variation of maximum pressure of the cycle, rate of hear release, rate of mass burned, and combustion delay are influenced by the inlet air humidity in the spark-ignition engine. The quantitative combustion delay can be obtained from the rate of mass burned. Also, the variation of time loss and effective compression ratio with the change of inlet air humidity are dominated by the development of rate of heat release.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권11호
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• pp.741-746
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• 2004

When investigating a control problem for network based control systems, the main issue is network-induced delay. This delay can degrade the performance of control systems designed without considering the delay and even destabilize the system. In this paper, we consider the stabilization of network based control systems, where there is bounded time-varying delay. This delay is treated like parameter variation of a discrete time system. The state feedback controller design is formulated as linear matrix inequality. Finally, we show that the stability of control systems designed with considering the delay is superior to that is not so.

• 한국측량학회지
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• 제30권6_2호
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• pp.673-680
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• 2012

Long-term GPS data analysis was performed in order to analyze the seasonal variation of tropospheric delay and the success rate of the ambiguity resolution. For this analysis, a total of 57 stations including 10 IGS stations in East Asia were processed together with double-differenced observables using Bernese GPS Software V5.0. The time span for this study ranges from 2002.0 to 2012.5 (10.5 years). The average baseline length is 339.0 km and the maximum reaches up to 2,000 km. The analysis is focused on two things: the annual variation of the tropospheric delay and the ambiguity resolution rate. The tropospheric delay is closely related to the weather condition, especially relative humidity, therefore it was estimated that the maximum would be in summer, while reaching its minimum in winter with the apparent seasonal variations. On the contrary, however, the success rate of the ambiguity resolution shows the opposite pattern: its maximum was in winter and minimum in summer. The fact seems to be induced by the surrounding conditions; that is, the trees thick with leaves near the GPS antenna interfere with GPS signals in summer. This seems to confirm partly that there is a distinct trend in the decreasing success rate since 2006 because the trees are growing every year. It is necessary to eliminate the factors that degrade the GPS quality and the tropospheric modeling for Korea needs to be studied further.

• 대한원격탐사학회지
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• 제18권2호
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• pp.91-96
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• 2002

고정 검출 시간(Integration Time)을 갖고 Time Delay and Integration(TDI) Charge Coupled Device (CCD) 검출기를 사용하는 위성 영상 기기에서 위성의 고도 및 촬영각의 변화에 대한 영상 기기의 기하 성능 특성을 TDI 불일치와 관련하여 분석하였다. 본 분석을 통하여 고도 저하에 따른 기하 성능 저하를 보완할 수 있는 방법으로서 경사 촬영을 통한 TDI 불일치 제거를 제안하였고 저하된 고도에서 TDI 일치로 최적 성능을 줄 수 있는 최적 경사 촬영각을 구하였다. 본 결과는 임의의 범위의 가변 검출 시간을 갖는 TDI CCD 위성 영상 기기에도 적용 가능하다.

• Journal of Advanced Marine Engineering and Technology
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• 제28권4호
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• pp.603-610
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• 2004

Time delays are included in most of actual systems, and some of which are shown as time varying. To analyze the time varying time delay system in the time domain. a useful delay module to express the function as a tool is much helpful to get corresponding outputs under given conditions. A method is proposed here to design the algorithm of time delay module for simulation or control purposes, including the problems of initializing and reallocating data in buffer. After classifying the time varying time delay into the distributed mode and lumped mode, an object to describe delay module is configured and tested under the defined input signal and given time delay variation. The simulation results show that the output of module matches reasonably with the case of real system.

• 정보처리학회논문지C
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• 제13C권3호
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• pp.353-358
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• 2006

TCP 구현의 하나인 Vegas는 패킷의 유실을 망의 혼잡으로 인지하는 Reno와 달리 RTT(Round Trip Time) 측정값을 바탕으로 혼잡을 인지하며, 이를 이용하여 윈도우 크기 등 혼잡 제어를 위한 주요 인자를 결정한다. 그러나, Vegas의 혼잡 회피 방안이 TCP 패킷 경로의 비대칭적 특성을 제대로 반영하지 못하며, 이것은 양 방향(순방향, 역방향) 패킷 전송 상태를 반영하는 RTT 측정값을 순방향 경로의 상태 해석에 이용하기 때문이다. RTT는 패킷의 왕복 시간만을 측정하기 때문에 패킷의 송수신시 순방향과 역방향에서 어느 정도의 혼잡이 발생하였는지 알 수 없다. 본 논문에서는 리눅스 커널 2.6의 TCP 소스에서 RTT 측정값으로 혼잡도를 측정하는 기존의 Vegas 혼잡 제어 알고리즘을 수정하여 순방향 경로의 혼잡과 역방향 경로의 혼잡을 구별할 수 있는 새로운 Vegas 혼잡 제어 알고리즘을 설계하고 구현하여 그 성능을 분석하였다.

• 한국ITS학회 논문지
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• 제13권1호
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• pp.15-25
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• 2014

버스우선신호는 도로상에서 버스에 물리적, 운영적 통행우선권을 부여하는 방법으로 신호 교차로에서 버스의 정시성 및 신속성, 서비스 개선을 통해 승객의 수송 효율과 도로 교통의 수송 용량을 높일 수 있는 대중교통 우선정책 기법이다. 본 연구에서는 결정적 지체모형의 하나인 HCM모형을 이용하여 중앙버스전용차로가 존재하는 독립교차로에서 능동형 버스우선신호 제공 방법론을 제시하였다. 능동형 버스우선신호의 기법 중 Early green과 Green extension 기법을 이용하여 버스가 이용하지 않는 비우선현시의 여유녹색시간을 버스가 이용하는 우선현시에 재분배하는 버스우선신호 방법론을 제시하였다. 또한, 이 방법론을 통하여 비우선현시의 여유녹색시간을 우선현시에 재분배 하였을 때 차량당 지체 및 사람당 지체가 어떻게 변화하는지에 대하여 분석하고 여유녹색시간의 민감도 분석을 통해 여유녹색시간이 정확한 값인지 알아보았다. 그 결과 교차로 전체의 차량당 지체는 다소 증가하고 사람당 지체는 감소하는 것으로 나타났다. 또한, 민감도 분석결과 여유녹색시간의 변화가 30%미만일 경우 지체의 큰 차이는 없었으나 30%이상일 경우 버스우선신호의 효과가 떨어지는 것으로 분석 되었다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권4호
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• pp.397-404
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• 2012

Thermal generation by power dissipation of the highly integrated System on Chip (SoC) device is irregularly distributed on the intra chip. It leads to thermal increment of the each thermally different region and effects on the propagation timing; consequently, the timing violation occurs due to the misestimated number of buffers. In this paper, the timing budgeting methodology considering thermal variation which contains buffer insertion with wire segmentation is proposed. Thermal aware LUT modeling for cell intrinsic delay is also proposed. Simulation results show the reduction of the worst delay after implementing thermal aware buffer insertion using by proposed wire segmentation up to 33% in contrast to the original buffer insertion. The error rates are measured by SPICE simulation results.

• 한국대기환경학회지
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• 제9권1호
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• pp.93-100
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• 1993

This study was carried out to investigate the relationship between the traffic signal systmes and the air pollutants emitted by the motor vehicles at Kangnam Intersection. One of the most important measures of effectiveness (MOE) in traffic studies is the delay to vehicles in the system. Delay represents indirect costs to the motorist in terms of time loss and a direct cost in terms of fuel consumption during idling. The results of TRANSYT-7F modeling was correlated among delay, fuel consumption and total travel tiem. Air pollutants emission rate can be calculated by the results of modeling and the Korean type emission factor. As expected the highest emissions, for air pollutants, are observed during the morning rush hours (07 : 00-10 : 00). For better results of modeling, the TRANSYT-7F model needs to modify for the Korean type of traffic model. The results of this study indicate that the variation of air pollutants emission rates were closely related to the traffic signal system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.1004-1011
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• 1996

This paper covers the technology developmental stage work for the automatic ammunition loading system mainly focusing on the controller design of the electro-hydranlic type direct drive multi-axis manipulator. Mathematical model of the plant derived and PIDM servo-controller structured. Comparative study between the analytical and experimental work has been carried out to help understand the response property of the direct dine multi-axis robot. In the direct drive robot, non-negligible amount of disturbance and load Induced dynamics variation are transmitted to the drive axis and nonlinearity is highly observed. Thereupon a robust controller Implementing time-delay control law is proposed, and computer simulation confirms the possibility for the time-delay control application against the unpredictable disturbance and load-Induced dynamics variation.