• Journal of the Korean Applied Science and Technology
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• 제35권4호
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• pp.1134-1144
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• 2018

Cetane Number is one of the quality standard for diesel, which assesses the compatibility of ignition quality of diesel compression in diesel engines. Cetane number must be upper 52 to keep the recent diesel quality standards. It is known that if cetane number is high, there will be shorter ignition delay periods than being lower. On the other hands, if cetane number is too high that exceeds the quality standard, there will increase the air pollution and decrease of the fuel efficiency because incomplete combustion. In South Korea, various methods are being used to measure the cetane number such as cetane number that used CFR engine, cetane index from calculate density and distillation temperature and derived cetane number to make up for CFR engine that ignition delay in high temperature is implemented. In this study will be conducted by collecting the diesel from the major oil companies, and try to analyze the correlation between the different methods of cetane number with various factors. At the results of this study, it was shown that the cetane index is high then cetane engine and derived cetane number. therefore it will be necessary to additional research for out of cetane number quality standards.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• 제11권6호
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• pp.15-22
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• 2012

A performance index of singalized intersections is a standard to optimize signal control variables and to manage traffic flow. Traffic delays is generally used to minimize the average delay time on intersections or networks, progression efficiency is used to improve travel speed of main cooridors or to provide transit signal priority. We manage traffic flows with only selecting one index between delays and progression according to the objective of traffic management and field characteristics. In real field, the driver's satisfaction is high in any performance criteria when the waiting time is shorter and the unnecessary stop in front of traffic is smaller. This paper aims to develop simulation model to represent real progression with concurrently considering delays and progression. In order to reflect an effect of level of traffic volumes and residual queues which don't be considered in prior progression model, we apply shockwave model with flow-density diagram. We derive Cell Transmission Model of Daganzo in order to develop the delay index and the progression index for the macroscopic simulation model. In order to validate the effect, we analysis traffic delays and progression efficiency with comparing this model to Transyt-7F and PASSER V.

• Korean Journal of Optics and Photonics
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• 제22권6호
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• pp.256-261
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• 2011

In this paper, a variable optical signal delay line based on coupled ring resonators is designed and fabricated in high-index contrast polymer material. The free spectral ranges (FSR) of the rings are designed to be 100 GHz, and 8 coupled rings are used. When two rings near a bus waveguide are in resonance, the optical delay is measured to be about 100 ps. When four rings are in resonance, the measured delay is about 180 ps. Both are close to the theoretical calculations.

• Journal of Astronomy and Space Sciences
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• 제25권3호
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• pp.267-282
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• 2008

The GNSS (Global Navigation Satellite System) signal is delayed by the neutral atmosphere at the troposphere, so that the delay is one of major error sources for GNSS precise positioning. The tropospheric delay is an integrated refractive index along the path of GNSS signal. The refractive index is empirically related to standard meteorological variables, such as pressure, temperature and water vapor partial pressure, therefore the tropospheric delay could be calculated from them. In this paper, it is presented how to generate meteorological data where observation cannot be performed. KASI(Korea Astronomy & Space Science Institute) has operated 9 GPS (Global Positioning System) permanent stations equipped with co-located MET3A, which is a meteorological sensor. Meteorological data are generated from observations of MET3A by Ordinary Kriging. To compensate a blank of observation data, simple models which consider periodic characteristics for meteorological data, are employed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제28권11호
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• pp.748-751
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• 2015

Sound Masking System technology as by sound the same on all bands and artificially generates a constant sound shield People want to hear or recognize the people with the noise generated from the interior of the way. Prevent hearing or prevent recognition by using the technology to control the audible frequency band Continue to emit constant and uniform shielding sound audible frequency band Even the security content of speech (20 Hz~20 KHz). That interception laser eavesdropping, internal solicitations, during recording Or delay the decoding was a result of the effect of interference calculated Experience noise disturbance index is applied around the Stress Index is the average index is 10.16 was a luxury for the average index is then applied to the index 3.07 Noise is significantly lower stress level has improved noise conditions.

• Journal of Advanced Marine Engineering and Technology
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• 제33권5호
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• pp.721-728
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• 2009

PID control is widely used to control stable processes, however, PID control for unstable processes is less common. In this paper, systematic tuning methods are derived to tune the PID controller for unstable FOPTD(Forst Order Plus Time Delay) processes. The proposed PID controllers for set-point tracking and disturbance rejection problem are tuned based on minimizing the performance indexes (IAE, ISE, ITAE) using a real-coded genetic algorithm. Simulation example is given to illustrate the set-point tracking and disturbance rejection performance of the proposed method.

• Journal of Nutrition and Health
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• 제26권4호
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• pp.443-454
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• 1993

The purposes of this study were to analyze the work patterns of selected hospital foodservices by Work Sampling methodology, and to investigate the relationship among operational factors affecting productivity. The hospitals were classified into 3 groups by the percentage of patient meals, and the percentage of special patient diet, and the menu items of patients meals. The groups clustered were characterized by productivity. Work Sampling methodology was utilized to analyze the work patterns of hospitals with selected 3 hospitals to investigate the productivity the productivity and labor times used in each work functions. Productivity index analyzed by Work Sampling were 10.36 min/meal, 10.95 min/meal, and 12.19 min/meal, respectively X, Y, Z hospital. Z hospital was significantly different from time used in direct work function and delay. Direct work function time was the highest, delay the lowest in Z hospital. The relation between the results of Work Sampling and the productivities of 3 groups showed not by delay but direct work function in the classification used in this study.

• Korean Journal of Optics and Photonics
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• 제27권5호
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• pp.174-180
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• 2016

A tunable optical delay line is designed, fabricated, and characterized. The tunable delay line consists of four polymer-ring add/drop filters with delay waveguides between adjacent ones. The polymer waveguide is a buried structure, designed to be square with core width and height of $1.8{\mu}m$. The refractive indices of the core and cladding polymer are 1.48 and 1.37 respectively. The large index difference and small cross section of the waveguide enable us to realize a compact device using a small radius of curvature. Four pairs of electrodes are evaporated above the add/drop filters to provide heating currents for thermal tuning. In measurements we can identify variable time delays of 110, 225, and 330 ps in proportion to the number of delay lines.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제56권4호
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• pp.790-794
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• 2007

This paper presents a new index mapping method for DFT (Discrete Fourier Transform) and its application to multidimensional DFT. Unlike conventional index mapping methods such as DIT (Decimation in Time) or DIF (Decimation in Frequency) algorithms, the proposed method is based on two levels of decomposition and it can be very efficiently used for implementing multidimensional DFT as well as 1-dimensional DFT. The proposed pipelined architecture for multidimensional DFT is very flexible so that it can lead to the best tradeoff between performance and hardware requirements. Also, it can be easily extended to higher dimensional DFTs since the number of CEs (Computational Elements) and DCs (Delay Commutators) increase only linearly with the dimension. Various implementation options based on different radices and different pipelining depths will be presented.

• Journal of Auto-vehicle Safety Association
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• 제5권1호
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• pp.50-55
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• 2013

When it comes to commercial vehicles, their unique characteristics - center of gravity, size, weight distribution - make them particularly vulnerable to rollover. On top of that, conventional heavy vehicle brake exhibits longer actuation delays caused in part by long air lines from brake pedal to tires. This paper describes rollover prevention algorithm that copes with the characteristics of commercial vehicles. In regard of compensating for high actuating delay, predicted rollover index with short preview time has been designed. Moreover, predicted rollover index with longer preview time has been calculated by using road curvature information based on environment information. When rollover index becomes larger than specific threshold value, desired braking force is calculated in order to decrease the index. At the same time, braking force is distributed to each tire to make yaw rate track desired value.