• Journal of Sensor Science and Technology
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• v.23 no.3
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• pp.149-157
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• 2014

This paper considers the ability of counting and positioning multi-targets by using a mobile UWB radar device. After a background subtraction process, distinguishing between clutters and human body signals, the position of targets will be computed using weighted Gaussian mixture methods. While computer vision offers many advantages, it has limited performance in poor visibility conditions (e.g., at night, haze, fog or smoke). UWB radar can provide a complementary technology for detecting and tracking humans, particularly in poor visibility or through-wall conditions. As we know, for 2D measurement, one method is the use of at least two receiver antennas. Another method is the use of one mobile radar receiver. This paper tried to investigate the position detection of the stationary human body using the movement of one UWB radar module.

• Journal of Environmental Science International
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• v.23 no.7
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• pp.1241-1251
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• 2014

The study investigates weekday/weekend characteristics of $PM_{10}$ and $PM_{2.5}$ concentrations and meteorological elements in Busan. The $PM_{10}$ concentration is highest on Wednesday and Thursday, and lowest on Sunday. On the other hand, the $PM_{2.5}$ concentration is highest on Wednesday and lowest on Sunday. The location where concentrations of weekdays and weekend differ the most is Hwakjang-dong, the industrial area, and where they differ the least is Gijang-up and Joa-dong, the residential area. Fine particle concentration in the industrial area was consistent at dawn and in the morning, but varied in the afternoon and at night. The visibility of Sunday was 0.49 km higher than that of weekdays, and the solar radiation of Sunday was $0.11MJ/m^2$ higher than that of weekdays. These results indicate that the concentration of fine particles had influence on the change of visibility and solar radiation.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.2
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• pp.101-108
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• 2015

In this paper, a robust traffic light detection method is proposed by using vision sensor and DGPS(Difference Global Positioning System). The conventional vision-based detection methods are very sensitive to illumination change, for instance, low visibility at night time or highly reflection by bright light. To solve these limitations in visual sensor, DGPS is incorporated to determine the location and shape of traffic lights which are available from traffic light database. Furthermore the geometric relationship between traffic light and vision sensor is used to locate the traffic light in the image by using DGPS information. The empirical results show that the proposed method improves by 51% in detection rate for night time with marginal improvement in daytime environment.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.5
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• pp.311-317
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• 2011

The blind spot is an area where drivers visibility does not reach. When drivers change a lane to adjacent lane, they need to give an attention because of the blind spot. If drivers try to change lane without notice of vehicle approaching in the blind spot, it causes a reason to have a car accident. This paper proposes a night-time blind spot vehicle detection using cameras. At nighttime, head-lights are used as characteristics to detect vehicles. Candidates of headlight are selected by high luminance feature and then shape filter and kalman filter are employed to remove other noisy blobs having similar luminance to head-lights. In addition, vehicle position is estimated from detected head-light, using virtual center line represented by approximated the first order linear equation. Experiments show that proposed method has relatively high detection porformance in clear weather independent to the road types, but has not sufficient performance in rainy weather because of various ground reflectors.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.401-406
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• 2010

Vessel Operator has been navigating with subjective sate distance in accordance with night & daytime, fore & aft, port & stbd abeam and visibility situation. This sate distances may different depending on inside & outside harbor limit, current, wind and visibility situation. By now, the concept of proper sate distance between navigating vessels has been adopted in Korea, using the early 1980's foreign data. And the safe distance is being used with the same value without any consideration of inside & outside harbor and the kind of vessel. So it is necessary to evaluate or search proper distance concept based on different sate consciousness of Korean manners. This paper aims to develop the basic model for marine traffic evaluation and the new model of marine traffic congestion. Also this paper proposes the basic control guideline of vessel traffic service center. The result of this study showed that minimum sate distance should be 4.4L forward, 3.1L aft and 26L abeam in case of good visibility in daytime, considering various parameters such as visibility, day and night. Some differences Here found between the existing minimum sate distance and the new minimum sate distance derived from the result of this study.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.257-263
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• 2013

In case of image observation equipments, CCTV for short distance visual field is usually installed and operated mostly as the means of crime-prevention. However, the extensive demand for monitoring problems in case of the increase in intelligent crimes and disasters has led to the necessity of the development of long-distance observation equipments embedded with Night View functions. In case of the Night View equipments, the relevant market is set up to be focused mostly on Thermal Observation Device(hereinafter, TOD), but some shortcomings such as the limitation of image visibility and excessive maintenance cost, etc. have actually caused the necessity of new long distance Night View equipment. Moreover there might follow lots of difficulties in long-distance visualization in the event that irregular reflection is generated by minute particles in the atmosphere such as fog, smog, and dust, etc. These factors are motivate the work presented in this study. Our study is aimed at the realization of Pulsed Laser Illuminator and newly proposed Range-Gated image acquisition technology. And also the implementation of Tracker for continuous trace of the objects of interest from the obtained sequence images.

• International Journal of Highway Engineering
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• v.18 no.6
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• pp.145-152
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• 2016

OBJECTIVES : Visibility at night can be improved by using retroreflection for short distances and phosphorescent line markings for long distances. In this study, we analyzed the characteristics of the phosphorescent line marking through a laboratory luminance test. Field performance analysis was performed through tests conducted on the road. We also examined the luminance measurement methods using the digital image obtained during the phosphorescent visibility evaluation. METHODS : In this study, the laboratory luminance test of the phosphorescent line marking was conducted using seven specimens to characterize the luminance changes according to the type of the glass beads, the thickness of the phosphorescent line marking, and the brightness and irradiation time of the light source. Phosphorescent and general line markings were made at 150 m to investigate the field luminance performance. A preliminary review of the luminance measurement methods was made using a digital image from a digital single-lens reflex (DSLR) camera. The measured luminance ratio of the general and the phosphorescent line markings was compared with the calculated luminance ratio using luminance analysis. RESULTS : Through the laboratory luminance test, it was seen that the change in luminance, which corresponds to the brightness of the light source, appears large but the influence of the thickness and irradiation time is low. The field performance test of the phosphorescent line marking conducted on the road involved measuring the luminance on the day the marking was made and 7 days after the marking was made. The luminance was found to be $190mcd/m^2$ at 30 min after sunset and approximately $10-12mcd/m^2$ 4h after sunset. The results of the luminance test were captured using a digital image for each time group. The luminance ratio of the phosphorescent line marking, when compared to that of the general line marking, showed a similar trend within a 13% maximum error. Additionally, when this luminance ratio is compared to the direct field measurement, it could be confirmed that the luminance ratio, as captured in the digital image, showed a similar tendency. CONCLUSIONS : 1) The change in luminance corresponding to the brightness of the light source is significant in comparison with that corresponding to the thickness and the irradiation time. In addition, the results of the field test for the phosphorescent line marking satisfied the phosphorescent fire protection standard. 2) We examined the validity of the luminance measurement method using a digital image and we concluded that the change in the luminance ratio shows a similar tendency in both the cases. The results can form the basis for luminance measurement methodology for the construction and maintenance of phosphorescent line markings.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.159-165
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• 2013

One of the leading causes of night time automobile accidents is the darkness of surroundings. Headlamps play a critical role in casting light and providing drivers with visibility. Headlamp design and new technology have been developed recently as research has been actively carried out to increase headlamp recognition. This study statistically analyzes irradiation distance using computer simulation by categorizing headlamps applied in domestic automobiles in the last decade by year, light source, form, vehicle type, and height of installation. After analyzing results of irradiation distance, it appears irradiation distance has been increased by approximately 10m in the last decade. This increase in irradiation distance is predicted to decrease night time accidents by allowing more time to recognize potential causes of accidents.

• International Journal of Highway Engineering
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• v.18 no.4
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• pp.69-75
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• 2016

PURPOSES : In this study, we evaluated changes in the retroreflectivity and luminance of phosphorescent road line markings with changes in glass beads and line marking thickness. METHODS : The color of line markings affects their retroreflectivity. Using a chromaticity test, we conducted the analysis of whether phosphorescent road line markings adhered to the "KS M 6080" standard. Then, we measured the dry retroreflectivity and wet retroreflectivity for various glass bead refractive indices. We conducted wet retroreflectivity test using the EN 1436 standard as the basis. We also conducted luminance tests for different glass bead refractive indices and line marking thicknesses. RESULTS : 1. Phosphorescent road line markings specimens satisfied the "KS M 6080" standard. 2. In dry retroreflectivity test, phosphorescent road line markings sprayed with glass beads satisfied the national police agency standard ($240mcd/(m^2{\cdot}Lux)$). Wet retroreflectivity test results showed that except for one type of No.1 glass beads, phosphorescent road line markings specimens sprayed with glass beads of one type of No.3 and two types of No.1 satisfied the national police agency standard ($100mcd/(m^2{\cdot}Lux)$). 3. Phosphorescent road line markings had higher retroreflectivity than non-phosphorescent road line markings in the dry condition. 4. Phosphorescent road line markings sprayed with glass beads demonstrated improved luminance. Luminance increased with higher glass bead refractive index and with increased line marking thickness. However, when the thickness crossed a certain threshold, phosphorescence ceased to increase; this is a characteristic of the phosphorescence phenomenon. CONCLUSIONS : Visibility across short distances can be ensured when phosphorescent road line markings are sprayed with glass beads, because of the retroreflection phenomenon. It is also possible to ensure far visibility using phosphorescent road line markings.

• Journal of Digital Convergence
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• v.14 no.1
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• pp.181-187
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• 2016

Typical Retro-reflectors installed on road have problems such as limiting a driver's visibility at night when it is foggy or rainy. On the other hand, LED illuminated studs, called cat's eye system, extends a driver's visibility under these conditions. In this paper, we present a design of the LED cat's eye system using solar energy that can sustain vehicles with about 30-ton weight and is compliant with the IP68 code for water proof as IEC standard 60529. In addition, we propose a scheme of designing a LED driving circuit consuming low power to take into accounts cold weather or rainy season with limited sunlight. This LED cat's eye studs is currently installed and used on expressway and bike route nationally as well as overseas.