• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.386-391
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• 2019

This paper presents analysis results for the effect of the directional group delay of the antenna to implement a precision radio navigation system. The analysis was conducted through antenna simulation and test, and the test was performed in an anechoic chamber. The directional group delay of the antenna was calculated in phase-based analysis method. The results showed that a variation of up to 7.7ns in group delay occurred per antenna direction. The group delay variation from the analysis is 2.31 meters when converted into distance. It was tested using a real radio navigation system based on the time of arrival (TOA). The test verified the distance variation of 2.1 meters, and this value is similar to those obtained from the simulation and chamber test analysis.

• Journal of Communications and Networks
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• v.1 no.3
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• pp.189-200
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• 1999

For admitting a hard real-time connection to an ATM network, it is required that the end-새둥 delays of cells belong-ing to the connection meet their deadlines without violating the guarantees already provided to the currently active connections. There are two kinds of methods to analyze the end-to-end delay in an ATM network. A decomposed method analyzes the worst case delay for each switch and then computes the total delay as the sum of the delays at individual switches. On the other hand, an integrated method analyzes all the switches involved in an inte-grated manner and derives the total delay directly. In this paper, we present an efficient and effecitive integrated method to compute the end-to-end delay. We evaluate the network performance under different system parameters and we compare the performance of the proposed method with the conventional decomposed and other integrated methods [1], [3], [5]-[9].

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.305-311
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• 2019

In this study, present the most useful delay scan time by statistical analysis of SUVm data for 30 suspected pancreatic cancer patients. Two statistical analysis and a mathematical model was applied to the theoretical formula by glucose and insulin mechanics, and a mathematical model was created. Statistical analysis was performed via Metlab p/g. Optimal delay scan time was suggested by Metlab p/g for the change of SUV value over time.In this study, for diagnosis pancreatic cancer by dual time point PET/CT, propose optimal delay scan time 131.5 minuts. The proposed delay scan time showed statistical reliability applicable to the diagnosis of pancreatic cancer (p<0.05). Delayed scanning with the suggested delay scan time of 131.5 minutes is considered to be useful for the diagnosis of pancreatic cancer compared to general PET / CT scan.hen the delayed test is performed with the proposed delay scan time 131.5 minuts, Compared with general PET/CT scans.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2004.11a
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• pp.250-255
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• 2004

To analyze delay, Seoul - Daegu line of Korea High Speed Railway was divided into three sections and analyzed independently by the business characteristics. The analysis on the project delay reasons was performed on macro and micro scales. This analytic method was named as 'Macro-Micro Delay Analysis Method (MMDAM)'. The macro scale analysis has three approaches, which are (1) scheduling, (3) structural characteristic, (3) and responsibility of project administrative works. Micro analysis also has three, methodologies which are (1) As Planned Method, (2) As Built method, (3) Modified Time Impact Analysis for analyzing the most influential section which the largest delay occurred. Using elicited project delay reasons from above analysis, the questionnaire was carried out for analyzing the influence of project delay reason. The reasons of the delay were driven from two different aspects (1) structural characteristic and (2) responsibility of the people involved in the project. The reasons that were identified from aforementioned three sections are the factors of the delay of the large-scale government driven projects. Finally, the author suggested the methodology of identifying the project delaying factors. The author also analyzed delay reasons in both the overseas and domestic cases of high rapid railway construction and has elicited some benchmarks for the future projects.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.2
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• pp.81-87
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• 1996

Time delay control(TDC) law has been recently suggested as an effective control technique for nonlinear time-varying systems with uncertain dynamics and/or unpredictable disturbances. This paper focuses on the applications of the TDC algorithm to torque control of an engine system and speed control of an engine/automatic transmission system. Through the stability analysis of the engien system based on TDC, determination of the appropriate time delay and control factor is investigated. It was revealed that the size of time delay of the TDC law should be greater than that of transport delay of the system for both stability and better control performance. Simulation and experimental results for the engine torque control and engine/automatic transmission speed control systems show both relatively good command following and disturbance rejection properties. However, TDC controller shows rather slow responses when applied to the system with large transport delay.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.43-44
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• 2006

The performance of the direct adaptive time-delay filter depends on the select time-delay. In this paper, the authors introduce a new scheme to adapt the time-delay which is to be used in conjunction with the direct adaptive command shaping for the improved vibration suppression in flexible motion system. In order to formulate the time-delay adaptation scheme, the authors have analyzed the effect of the time-delay value on the performance of the direct adaptive command shaping filter. By modifying the direct adaptation formula based on the analysis result the authors have established a set of equations to adapt the time-delay toward the optimal value. Simulation results show the effectiveness of the proposed time-delay adaptation approach for the improved vibration suppression.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.4
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• pp.200-207
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• 2004

This paper presents a simple and fast delay metric RC-class interconnects under saturated ramp inputs. The RC delay metric under saturated ramp inputs, called FDM(Fast Delay Metric), can estimate delay times at an arbitrary node using a simple closed-form expression and is extended from delay metric under step input easily As compared with similar techniques proposed in previous researches, it is shown that the FDM technique complexity for a similar accuracy. As the number of circuit nodes increases, there will be a significant difference in estimation times of RC delay between the previous techniques based on two circuit moments and the FDM which do not depend on circuit moments.

• Journal of Korean Society of Transportation
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• v.13 no.1
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• pp.125-152
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• 1995

The purposes of this study are twofold ; (1) to investigate the accuracy of estimation power of the individual models. such as those of Highway Capacity Nanual (HCM), Korea Highway Capacity Manual (KHCM), and NationalCooperative Highway Research Program(NCHRP) Report339 ; and (2) to develop an adjusted delay model which can be applied to the signal control system in urban areas. The study is mainly focused on four subjects related to the research purposes, which are as follows ; (1) characteristecs of exsisting delay models ; (2) inherent problems in exsisting delay models : (3) validation of the proposed model by the comparison of observed delay with estimated delay :and (4) a method which can be applied to develop an appropriate delay model for actrual signal control systems by the adjusted fact of the proposed model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.265-270
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• 2004

This paper addresses the effect of group delay in satellite communication system. Phase of signal is distorted by the non-constant group delay. Group delay can be modeled as linear, parabolic and cubic type according to the polynomial characteristic. We investigate BER performance of satellite communication system with each 3 kinds of group delay. As signal bandwidth becomes wider, group delay makes more influence on the signal. BNR performance of satellite communication system is found when data rates are 1Mbps, 4Mbps and 8Mbps. Convolution coding with the code rate of 1/2 or 7/8 is used. At BER =10$\^$-5/, system with group delay needs more SNR of minimum 0.3㏈ to maximum 4.4㏈ than system without group delay. The worst case of BER performance happens in the linear group delay, 7/8 punctured convolution coding and 8 Mbps. The required SNR is increased by 4.4㏈ at this worst case.

• Journal of ILASS-Korea
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• v.25 no.3
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• pp.119-125
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• 2020

In this paper, we used Helmholtz solver based on 3D finite element method to quantitatively analyze the effects of change of gain, time delay and time delay spread, which are the main variables of flame transfer function, on combustion instability in gas turbine combustor. The effects of the variable of flame transfer function on the frequency and growth rate, which are the main results of combustion instability, were analyzed by applying the conventional heat release fluctuation model and modified one considering the time spread. The analysis results showed that the change of gain and time delay in the same resonance mode affected the frequency of the given resonance modes as well as growth rate of the feedback instability, however, the effect of time delay spread was not relatively remarkable, compared with the dominant effect of time delay.