• Bulletin of the Korean Space Science Society
• /
• 2004.10b
• /
• pp.360-363
• /
• 2004

This review is concerned with the MP (multipactor) phenomena of the diplexer for RFDU DM of next generation satellite. The MP discharge is serious problems to design RF components in space applications such ase damage of physical structure, performance degradation, and mission failure of the satellite. In this work, we employed the 3D finite element method (FEM) to calculate the critical gap points and adopted ESTEC curve, MP susceptibility zone, to analyze the maximum handling RF power in the diplexer. And this work also recommends that one should design the tx filter of the diplexer which is more wider bandwidth upto the points to escape the ears of the group delay especially the cavity type of RF components in space applications.

• ETRI Journal
• /
• v.28 no.3
• /
• pp.397-400
• /
• 2006

The multi-layer advanced high-performance bus (ML-AHB) BusMatrix proposed by ARM is an excellent architecture for applying embedded systems with low power. However, there is one clock cycle delay for each master in the ML-AHB BusMatrix of the advanced microcontroller bus architecture (AMBA) design kit (ADK) whenever a master starts new transactions or changes the slave layers. In this letter, we propose an improved design method to remove the one clock cycle delay in the ML-AHB BusMatrix of an ADK. We also remarkably reduce the total area and power consumption of the ML-AHB BusMatrix of an ADK with the elimination of the heavy input stages.

• Journal of the Korean Society of Combustion
• /
• v.22 no.3
• /
• pp.35-40
• /
• 2017

Jet aviation fuel is one of liquid fuel which are used in aircraft engines. Korean domestic jet fuel, called Jet A-1, is tested for measurement of ignition delay time by using a shock tube manufactured recently. The temperature varies from 680 to 1250 K and the pressure and equivalence ratio of Jet A-1/air are fixed 20 atm and 1.0, respectively, for this experiment. The ignition delay time data of Jet A-1 are compared with those of Jet A, which has similar properties to Jet A-1. The behavior of negative-temperature-coefficient (NTC) is observed in the temperature range 750-900 K. In addition, ignition delay time of iso-octane is measured, which is one of the surrogate components for jet aviation fuel. The experimental data are compared and validated with the previous results from the literatures. A surrogate fuel for the present Jet A-1 consists of 45.2% n-dodecane, 32.1% iso-octane, and 22.7% 1,3,5-trimethylbenzene. The predicted ignition delay time for the surrogate agrees well with the measured one for Jet A-1.

• Proceedings of the IEEK Conference
• /
• 2000.07a
• /
• pp.399-402
• /
• 2000

The reduction of chip area and delay is important purpose of Scheduling in High-Level Synthesis. This paper presents a scheduling approach with component selection. After obtaining a initial schedule taking only single-functional u-nits, the component selection of our approach attempts the reduction of chip area and/or delay by the selection more suitable components in a component library using Simulated Annealing.

• Journal of Korea Water Resources Association
• /
• v.32 no.6
• /
• pp.731-740
• /
• 1999

Autocorrelation function is widely used as a tool measuring linear dependence of hydrologic time series. However, it may not be appropriate for choosing decorrelation time or delay time ${\tau}_d$ which is essential in nonlinear dynamics domain and the mutual information have recommended for measuring nonlinear dependence of time series. Furthermore, some researchers have suggested that one should not choose a fixed delay time ${\tau}_d$ but, rather, one should choose an appropriate value for the delay time window ${\tau}_d={\tau}(m-1)$, which is the total time spanned by the components of each embedded point for the analysis of chaotic dynamics. Unfortunately, the delay time window cannot be estimated using the autocorrelation function or the mutual information. Basically, the delay time window is the optimal time for independence of time series and the delay time is the first locally optimal time. In this study, we estimate general dependence of hydrologic time series using the C-C method which can estimate both the delay time and the delay time window and the results may give us whether hydrologic time series depends on its linear or nonlinear characteristics which are very important for modeling and forecasting of underlying system.

• Journal of the Optical Society of Korea
• /
• v.18 no.6
• /
• pp.766-771
• /
• 2014

Single-ring all-pass filters with various coupling ratios are designed, fabricated, and characterized to assess the validity of the split-step time-domain modeling approach, which is considered for direct simulation of time-domain characteristics, such as optical delay, of various ring resonator devices. When the coupling ratio of the single-ring all-pass filter is 0.4 and 0.8, the delay time is measured to be about 145 and 42 ps respectively, which is comparable to the time-domain modeling results of 151 and 47 ps respectively. The measurements for two- and three-ring all-pass filters are also found to agree quite well with the simulation results. With these results it is confirmed that the split-step time-domain model could be efficiently incorporated into an optical-communication simulation module for ring resonator delay components in an all-optical packet switching system.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.20 no.2
• /
• pp.215-222
• /
• 2002

As the GPS signals propagate from the GPS satellites to the receivers on the ground, they are delayed by the atmosphere. The tropospheric delay consists of two components. The hydrostatic (or "dry") component that is dependent on the dry air gasses in the atmosphere and accounts for approximately 90% of the delay. And the "wet" component that depends on the moisture content of the atmosphere and accounts for the remaining effect of the delay. The Zenith Hydrostatic Delay (ZHD) can be calculated from the local surface pressure. The Total Zenith Delay (TZD) will be estimated and the wet component extracted later. Integrated water Vapor (IWV) gives the total amount of water vapor that a signal from the zenith direction would encounter. Precipitable Water Vapor (PWV) is the IWV scaled by the density of water. The quality of this PWV has been verified by comparison with radiosonde data(at Osan). We processed data for JULY 2 and JULY 14, 1999 from four stations(Cheju, Kwangju, Suwon, Daegu). We found the coincidence between PWV of the estimations using GPS and PWV of pressing the radiosonde data. The average of the difference between PWV using GPS and PWV using radiosonde was 3.77 mm(Std. ＝ $\pm$0.013 mm) and 2.70 mm(Std. = $\pm$0.0011 mm) at Suwon & Kwangju.

• International Journal of Aeronautical and Space Sciences
• /
• v.17 no.1
• /
• pp.64-72
• /
• 2016

The coverage area of a GNSS regional ionospheric delay model is mainly determined by the distribution of GNSS ground monitoring stations. Extrapolation of the ionospheric model data can extend the coverage area. An extrapolation algorithm, which combines observed ionospheric delay with the environmental parameters, is proposed. Neural network and least square regression algorithms are developed to utilize the combined input data. The bi-harmonic spline method is also tested for comparison. The IGS ionosphere map data is used to simulate the delays and to compute the extrapolation error statistics. The neural network method outperforms the other methods and demonstrates a high extrapolation accuracy. In order to determine the directional characteristics, the estimation error is classified into four direction components. The South extrapolation area yields the largest estimation error followed by North area, which yields the second-largest error.

• Fisheries and Aquatic Sciences
• /
• v.11 no.3
• /
• pp.140-148
• /
• 2008

We compared the quality and quantity of volatile components in salt-dried croakers prepared by different methods and obtained from different locations. In total, 110 compounds were found among regular- and delay-type salt-dried croakers purchased from two locations in Hong Kong. The major chemical classes included miscellaneous compounds(17), pyrazines(16), alcohols(15), and sulfur-containing compounds(13). Fish obtained in different locations but prepared by the same method differed only slightly in the number of identified compounds. In general, fish prepared by the delay method had a larger number of compounds compared to fish prepared by the regular method. Further, a greater number and higher levels of compounds were found in the fish obtained from one of the two locations. Overall, the delay preparation method resulted in a greater number of compounds with stronger intensity compared to the regular method.

• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.2317-2319
• /
• 2000

This paper presents a feedback controller for compensation time delay in the distributed control systems. In using network, controllers and sensors are distributed on a communications network, there exist time delays on communication lines between the system components. So, we deal with the controller using Smith predictor controller design issue for such systems. Particularly compensated for the time delay of the plant or controller involved integrator using Modified Smith predictor. Simulation and the results show the good performance for the modified Smith predictor control systems.