• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.474-478
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• 2018

For process safety, fire and explosion characteristics of combustible materials handled at industrial fields must be available. The combustion properties for the prevention of the accidents in the work place are flash point, fire point, explosion limit, and autoignition temperature (AIT) etc.. However, the combustion properties suggested in the Material Safety Data Sheet (MSDS) are presented differently according to the literatures. The accurate combustion properties are necessary to safely treatment, transportation and handling of flammable substances. In the chemical industries, n-ethylaniline which is widely used as a raw material of intermediate products and rubber chemicals was selected. For safe handling of n-ethyl aniline, the flash point, the fire point and the AIT were measured. The lower explosion limit (LEL)of n-ethylaniline was calculated using the lower flash point obtained in the experiment. The flash points of n- ethylaniline by using the Setaflash and Pensky-Martens closed-cup testers measured $77^{\circ}C$ and $82^{\circ}C$, respectively. The flash points of n-ethylaniline using the Tag and Cleveland open cup testers are measured $85^{\circ}C$ and $92^{\circ}C$, respectively. The AIT of the measured n-ethyl aniline by the ASTM E659 apparatus was measured at $396^{\circ}C$. The LEL of n-ethylaniline measured by Setaflash closed-cup tester at $77^{\circ}C$ was calculated to be 1.02 vol%. In this study, it was possible to predict the LEL by using the lower flash point of n-ethylaniline measured by closed-cup tester. The relationship between the ignition temperature and the ignition delay time of the n-ethylaniline proposed in this study makes it possible to predict the ignition delay time at different ignition temperatures.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.80-89
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• 2006

The rapid development of process technology and the introduction of new materials not only make it difficult for process control but also as a result increase process variations. These process variations are barriers to successful implementation of design circuits because there are disparities between data on layout and that on wafer. This paper proposes a new design environment to determine the interconnect worstcase with accuracy and speed so that the interconnect effects due to process-induced variations can be applied to designs of $0.13{\mu}m$ and below. Common Geometry and Maximum Probability methods have been developed and integrated into the new worstcase optimization algorithm. The delay time of the 31-stage Ring Oscillator, manufactured in UMC $0.13{\mu}m$ Logic, was measured, and the results proved the accuracy of the algorithm. When the algorithm was used to optimize worstcase determination, the relative error was less than 1.00%, two times more accurate than the conventional methods. Furthermore, the new worstcase design environment improved optimization speed by 32.01% compared to that of conventional worstcase optimizers. Moreover, the new worstcitse design environment accurately predicted the worstcase of non-normal distribution which conventional methods cannot do well.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.352-360
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• 2008

Recently Task Group (TG) 4 of the Institute of Electrical and Electronics Engineers (IEEE) 802.15a has been recommended a system with ranging capability in existence of multiple Simultaneous operating piconets (SOPs) as well as low-cost, low-power. According to the ranging service, coherent and non-coherent based ranging schemes using ternary code have been adopted as a standard. However it is hard to estimate an accurate time of arrival (TOA) in case of using direct sequence based TOA estimation method because pulse repetition interval (PRI) offered by TG is more limited than the maximum excess delay (MED) of channel. To mitigate inter pulse interference (IPI) problem, this paper proposes a non-coherent TOA estimation scheme using non-periodic transmission (NPT) pattern. The proposed receiver is based on a non-coherent energy detection considering with motivation of low rate wireless personal area network (LR-WPAN). TOA information is estimated via proper comparison with a prescribed threshold after the sliding correlation and search back window (SBW) process for reducing TOA error. To verify the performance of proposed ranging scheme, two distinct channel models approved by IEEE 802.15.4a TG are considered. According to the simulation results, we could conclude that the proposed scheme have performed better performance than the conventional method on the existence of multiple SOPs.

• Journal of Korean Society of Transportation
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• v.21 no.5
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• pp.83-95
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• 2003

This study aims to develop travel time estimation and prediction models on the freeway using measurements from vehicle detectors. In this study, we established a travel time estimation model using traffic volume which is a principle factor of traffic flow changes by reviewing existing travel time estimation techniques. As a result of goodness of fit test. in the normal traffic condition over 70km/h, RMSEP(Root Mean Square Error Proportion) from travel speed is lower than the proposed model, but the proposed model produce more reliable travel times than the other one in the congestion. Therefore in cases of congestion the model uses the method of calculating the delay time from excess link volumes from the in- and outflow and the vehicle speeds from detectors in the traffic situation at a speed of over 70km/h. We also conducted short term prediction of Kalman Filtering to forecast traffic condition and more accurate travel times using statistical model The results of evaluation showed that the lag time occurred between predicted travel time and estimated travel time but the RMSEP values of predicted travel time to observations are as 1ow as that of estimation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.22-29
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• 2023

In the evaluation of seismic performance for structural materials and components, the loading rate and axial force can have a significant impact. Due to time-delay effects between input and output displacements, It is difficult to apply high-rate displacement in cyclic tests and hybrid simulations. Additionally, the difficulty of maintaining a consistent vertical load in the presence of lateral displacement has limited fast and real-time tests performed while maintaining a constant vertical load. In this study, slow, fast cyclic tests and real-time hybrid simulations were conducted to investigate the rate dependency and the influence of vertical loads of Isolation Bearing. In the experiment, the FLB System including an Adaptive Time Series (ATS) compensation and a state estimator was constructed for real-time control of displacement and vertical load. It was found that the vertical load from the superstructure and loading rate can have a significant impact on the strength of the seismic isolation bearing and its behavior during an earthquake. When conducting experiments for seismic performance evaluation, they must be implemented to be similar to reality. This study demonstrates the excellent performance of the system built and used for seismic performance evaluation and enables accurate and efficient seismic performance evaluation.

• Horticultural Science & Technology
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• v.30 no.3
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• pp.270-277
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• 2012

Greenhouse industry has been growing in many countries due to both the advantage of stable year-round crop production and increased demand for fresh vegetables. In greenhouse cultivation, $CO_2$ concentration plays an essential role in the photosynthesis process of crops. Continuous and accurate monitoring of $CO_2$ level in the greenhouse would improve profitability and reduce environmental impact, through optimum control of greenhouse $CO_2$ enrichment and efficient crop production, as compared with the conventional management practices without monitoring and control of $CO_2$ level. In this study, a mathematical model was developed to estimate the $CO_2$ emission from soil as affected by environmental factors in greenhouses. Among various model types evaluated, a linear regression model provided the best coefficient of determination. Selected predictor variables were solar radiation and relative humidity and exponential transformation of both. As a response variable in the model, the difference between $CO_2$ concentrations at the soil surface and 5-cm depth showed are latively strong relationship with the predictor variables. Segmented regression analysis showed that better models were obtained when the entire daily dataset was divided into segments of shorter time ranges, and best models were obtained for segmented data where more variability in solar radiation and humidity were present (i.e., after sun-rise, before sun-set) than other segments. To consider time delay in the response of $CO_2$ concentration, concept of time lag was implemented in the regression analysis. As a result, there was an improvement in the performance of the models as the coefficients of determination were 0.93 and 0.87 with segmented time frames for sun-rise and sun-set periods, respectively. Validation tests of the models to predict $CO_2$ emission from soil showed that the developed empirical model would be applicable to real-time monitoring and diagnosis of significant factors for $CO_2$ enrichment in a soil-based greenhouse.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1435-1440
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• 2017

Recently, VR and AR are emerging as an area of interest in ICT. In virtual reality to feel like a real, many people are looking for them because of its charm. However, the motion of the VR image and the moving object are not synchronized exactly, and a problem of feeling nausea is also occurring. The problem should be solved by the application of Attraction in the VR system. In this paper, we propose a module that minimizes delay time by synchronizing movement of VR image and moving object. The proposed module calculates the moving distance using the direction and the acceleration sensor that the user views through the VR device. The module proposed in this paper will pay attention to the fact that the movement of the attraction moves along a fixed path, so that the accurate travel distance can be calculated.

• Explosives and Blasting
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• v.34 no.4
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• pp.10-18
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• 2016

Explosive blasting utilizes the energy produced from the explosion of explosive materials. Since the black powder, the first type of explosive, was invented, various types of explosives have been developed until a recent emulsion explosive which is powerful as well as safe in use. The detonators continue to be developed from safety fuse to the recent electronic detonators which allow extremely accurate and flexible control of delay time. However, the good explosives and detonators do not always lead to the good blast results. It entirely depends on the blast engineer. It is necessary to develop the empirical or theoretical models based on the field experience and sound theoretical algorithm. Such models would be very useful for blast design and, furthermore, provide the idea of further technical development. This paper introduces some models used in explosive blasting and attention to be paid for field application.

• Science of Emotion and Sensibility
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• v.14 no.4
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• pp.605-616
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• 2011

The present study examined memory accuracy for faces with positive, negative and neutral emotional expressions to test whether their emotional content can affect visual working memory (VWM) performance. Participants remembered a set of face pictures in which facial expressions of the faces were randomly assigned from pleasant, unpleasant and neutral emotional categories. Participants' task was to report presence or absence of an emotion change in the faces by comparing the remembered set against another set of test faces displayed after a short delay. The change detection accuracies of the pleasant, unpleasant and neutral face conditions were compared under two memory exposure duration of 500ms vs. 1000ms. Under the duration of 500ms, the accuracy in the pleasant condition was higher than both unpleasant and neutral conditions. However the difference disappeared when the duration was extended to 1000ms. The results indicate that a positive facial expression can improve VWM accuracy relative to the negative or positive expressions especially when there is not enough time for forming durable VWM representations.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.8 no.1
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• pp.26-30
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• 2015

There are many traumatic foot and ankle problems in orthopaedic fields. Though it is not life-threatening problems, a delay in accurate diagnosis and treatments can danger limb function and therefore correct diagnosis can prevent long-term complications. Achilles tendon rupture is relatively common injury for active sports people. Ultrasonography is cost-effective, irradiation -free, effective for evaluation of soft tissues and dynamic analysis. It has been growing importance in Achilles tendon rupture. Ultrasonography is a diagnostic tool in Achilles tendon rupture. Physical examination and patient history is needed to diagnose Achilles tendon without image, but it is missed up by 20% in private clinic. Discontinuity of normal fibrillar architecture seen on an ultrasonographic image is diagnostic for Achilles tendon rupture, and can be accentuated by the performance of dorsi-flexion and plantar flexion, while observing in real time. And ultrasonography is a reliable method for serial observation after surgical treatment or conservative treatment.