• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.4
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• pp.163-172
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• 2012

A driver assistance system is critical to improve a convenience and stability of vehicle driving. Several systems have been already commercialized such as adaptive cruise control system and forward collision warning system. Efficient vehicle detection is very important to improve such driver assistance systems. Most existing vehicle detection systems are based on a radar system, which measures distance between a host and leading (or oncoming) vehicles under various weather conditions. However, it requires high deployment cost and complexity overload when there are many vehicles. A camera based vehicle detection technique is also good alternative method because of low cost and simple implementation. In general, night time vehicle detection is more complicated than day time vehicle detection, because it is much more difficult to distinguish the vehicle's features such as outline and color under the dim environment. This paper proposes a method to detect vehicles at night time using analysis of a captured color space with reduction of reflection and other light sources in images. Four colors spaces, namely RGB, YCbCr, normalized RGB and Ruta-RGB, are compared each other and evaluated. A suboptimal threshold value is determined by Otsu algorithm and applied to extract candidates of taillights of leading vehicles. Statistical features such as mean, variance, skewness, kurtosis, and entropy are extracted from the candidate regions and used as feature vector for SVM(Support Vector Machine) classifier. According to our simulation results, the proposed statistical feature based SVM provides relatively high performances of leading vehicle detection with various distances in variable nighttime environments.

• Industrial Engineering and Management Systems
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• v.8 no.2
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• pp.80-92
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• 2009

This paper addresses the inventory rationing issue embedded in the regional supply chain inventory replenishment problem (RSIRP). The concerned supply chain, which was fed by the national supply chain, consisted of a single warehouse distributing a single product to multiple stores (M-stores) with independent and normally distributed customer demand. It was assumed that the supply chain operated under the order-up-to level inventory replenishment system and had only one truck at the regional warehouse. The truck could make one replenishment trip to one store per period (a round trip per period). Based on current inventories and the vehicle constraint, the warehouse must make two decisions in each period: which store in the region to replenish and what was the replenishment quantity? The objective was to position inventories so as to minimize lost sales in the region. The warehouse inventory was replenished in every fixed-interval from a source outside the region, but the store inventory could be replenished daily. The truck destination (store) in each period was selected based on its maximum expected shortage. The replenishment quantity was then determined based on the predetermined order-up-to level system. In case of insufficient warehouse inventories to fulfill all projected store demands, an inventory rationing rule must be applied. In this paper, a new inventory rationing rule named Expected Cost Minimization (ECM) was proposed based on the practical purpose. The numerical results based on real data from a selective industry show that its performance was better and more robust than the current practice and other sharing rules in the existing literature.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2387-2395
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• 2021

Seismic qualifications of electrical equipment, such as cabinet systems, have been emerging as the key area of nuclear power plants in Korea since the 2016 Gyeongju earthquake, including the high-frequency domain. In addition, electrical equipment was sensitive to the high-frequency ground motions during the past earthquake. Therefore, this paper presents the rocking behavior of the electrical cabinet system subjected to Reg. 1.60 and UHS. The high fidelity finite element (FE) model of the cabinet related to the shaking table test data was developed. In particular, the first two global modes of the cabinet from the experimental test were 16 Hz and 24 Hz, respectively. In addition, 30.05 Hz and 37.5 Hz were determined to be the first two local modes in the cabinet. The high fidelity FE model of the cabinet using the ABAQUS platform was extremely reconciled with shaking table tests. As a result, the dynamic properties of the cabinet were sensitive to electrical instruments, such as relays and switchboards, during the shaking table test. In addition, the amplification with respect to the vibration transfer function of the cabinet was observed on the third floor in the cabinet due to localized impact corresponding to the rocking phenomenon of the cabinet under Reg.1.60 and UHS. Overall, the rocking of the cabinet system can be caused by the low-frequency oscillations and higher peak horizontal acceleration.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.969-976
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• 2022

In this paper, a drunk driving prevention system was implemented to measure drunk driving before starting to prevent drunk driving accidents caused by complacency after drinking. In order to prevent a situation in which a driver but not a driver authenticates instead of a driver, the identification means was strengthened and the alcohol sensor was implemented to operate when the wind sensor measured above the set value set. Through this system, the driver's alcohol measurement process was strengthened. Sensors were determined through various experiments, and finally, when the alcohol concentration was 0.03% or more, the DC motor was stopped and the vehicle was designed to be unable to operate, thereby implementing a system in which drunk driving was prevented in advance.

• Journal of Korea Water Resources Association
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• v.53 no.4
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• pp.303-312
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• 2020

An underground deep tunnel system is a facility in form of a reverse siphon for an under flood defense structure. In this study, the 'Shinwol rainwater storage and drainage system', which is under construction for the first time in South Korea, in order to confirm the effects of undular bore and pressurized air on the hydraulic stability of the facility in various flood scenarios a hydraulic model experiment was performed. As a result of this study, it was analyzed that the undular bore generated downstream pushed the pressurized air collected in the facility while moving upstream, and the pressure inside the pipe increased at this time. It was analyzed that the pressure during the passage of the undular bore was greater than the sum of the static pressure and dynamic pressure at the time and overflow occurred when the cross-sectional size of the pressurized air was more than 40% of the cross sectional area of the tunnel. It is determined that this is correlated with the volume of pressurized air collected in the facility, and it is determined that it is necessary to study the relationship between velocity of undular bore and the volume of pressurized air in the future.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.3
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• pp.45-53
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• 1993

The shielding effectiveness of materials is determined by measuring the ratio of the incident electromagnetic power to that which passes through the material under test. The measurement system is constructed using several test fixtures, tracking generator, spectrum analyzer, step attenuator, RF switches, and amplifiers, etc.. The automation of measurements is completed using a personal computer. Especially, incident power, reflected power, and transmitted power are measured with only one spectrum analyzer using a dual directional coupler and RF switches. Therefore the system is to be used in design of shielding materials, as well as shielding effectiveness measurements. This system has dynamic range of more than 120 dB in the frequency range of 10 MHz to 1 GHz, and it can be used to measure shielding effectiveness of composite materials.

• Journal of the Korean Institute of Navigation
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• v.24 no.3
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• pp.157-165
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• 2000

When the GPS system was come to the operation, the U.S Coast Guard initiated development of differential GPS system based on a marine radiobeacon. It has rapidly been spread out to many countries. DGPS equals to P(Y) code in a positioning accuracy. USA has recently determined to expand the coverage of DGPS to inland in order to install a nationwide DGPS chain. Korea is under processing for improving the DGPS as a nationwide positioning system. Before expanding the service area inside Korea, we need to verify the relation between the field strength and DGPS accuracy for the service area. The Japanese DGPS data is received in the southern Part of the Korean peninsula. The Korean DGPS was not a complete system, so we selected the Japanese DGPS data as a model for the study. This paper investigate accuracy and reliability characteristics of RBN/DGPS over the effective service area. Through the experimental and simulation study, we obtained the reliable and stable positioning accuracy in the southern part of the Korean peninsula. In addition, the characteristics of RBN/DGPS were examined in the land over the effective coverage from Japan. The results would be a basic reference to research the RBN/NDGPS in Korea.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.6
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• pp.481-487
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• 2009

This paper proposes a regulation method of DC line voltage for urban transit system fluctuated during the acceleration or deceleration by using supercapacitor. Supercapacitor is modelled electrically under the assumption of three different time constants of RC circuits with variable capacitances depending on the voltage. And its parameters are determined by the experimental measurements. The energy storage system using supercapacitors is installed based on this model, and the proposed model is tested through the simulations and experiments, and the controller for charging and discharging is designed. Finally, it is tested at Kyoungsan test site for the urban light rail road system and the energy saving effect is evaluated economically.

• Journal of Broadcast Engineering
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• v.20 no.3
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• pp.440-448
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• 2015

A pedestrian collision warning system which makes a judgement of pedestrian's intention to help avoiding hitting accidents is proposed. This system uses the image sequences obtained from a car black box as well as vehicle's speed obtained from a GPS. It detects pedestrians, if any, based on the Histogram of Gradient method and extracts several information such as the pedestrian's relative positions, the direction of motion vectors, and distance between vehicle and pedestrian . A fuzzy logic based on these extracted information is applied to analyze the pedestrian's safety levels. When the safety level is determined to be danger, an alarm is triggered to the driver. The performance of the proposed algorithm is tested under various driving scenarios, which shows it works successfully in real-time.

• Nuclear Engineering and Technology
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• v.34 no.5
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• pp.421-432
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• 2002

As one of the advanced design features of the APR1400, direct vessel injection (DVI) system is being considered instead of conventional cold leg injection (CLI) system. It is known that the DVI system greatly enhances the reliability of the emergency core cooling (ECC) system. However, there is still a dispute on its performance in terms of water delivery to the reactor core during the reflood phase of a large-break loss-of-coolant accident (LOCA). Thus, experimental validation is under progress. In this paper, test results of direct ECC bypass performed in the steam-water test facility tailed MIDAS (Multi-dimensional Investigation in Downcomer Annulus Simulation) are presented. The test condition is determined, based on the preliminary analysis of TRAC code, by applying the ‘modified linear scaling method’with the l/4.93 length scale . From the tests, ECC direct bypass fraction, steam condensation rate and information on the flow distribution in the upper annulus downcomer region are obtained.