• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.3 no.1
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• pp.41-56
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• 1999

Since UV-B radiation measuring networks have not been established, numerical models which calculate the flux from other readily available meteorological measurements may play an important role. That is, such a problem can be solved by using parameterization models such as two stream approximation, the delta-Eddington method, doubling method, and discrete ordinate method. However, most UV-B radiative transfer models have not been validated with measurements, because such models are not intended as practical computational schemes for providing surface estimates of UV-B radiation. The main concern so far has been to demonstrate model sensitivity for cloudless skies. In particular, few have been concerned with real cloud information. Clouds and aerosols have generally been incorporated as constituents of particular atmospheric layers with specified optical depths and scattering properties. The parameterization model presented here is a combination of a detailed radiative transfer algorithm for a coludless sky radiative process and a more approximate scheme to handle cloud effects. The model input data requires a daily measurement of the total ozone amount plus a daily record of the amount and type of cloud in the atmosphere. Measurements for an examination of the models at the Department of Atmospheric Sciences, Pusan National University have been takenfrom February, 1995. These models can be used to calculate present and future fluxes where measurements have not been taken, and construct climatologies for the period before ozone depletion began.

• Journal of Biosystems Engineering
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• v.37 no.1
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• pp.11-18
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• 2012

Purpose: Short-circuit current of a solar module that is widely used as a power source for wireless environmental sensors is proportional to solar radiation although there are a lot of factors affecting the short-circuit current. The objective of this study is to develop a model for estimating solar radiation for using the solar module as a power source and an irradiance sensor. Methods: An experiment system collected data on the short-circuit current and environmental factors (ambient temperature, cloud cover and solar radiation) during 65 days. Based on these data, two linear regression models and a non-linear regression model were developed and evaluated. Results: The best model was a linear regression model with short-circuit current, angle of incidence and cloud cover and its overall RMSE(Root Means Square Error) was 66.671 $W/m^2$. The other linear model (RMSE 69.038 $W/m^2$) was also acceptable when the cloud cover data is not available.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.10
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• pp.4886-4907
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• 2019

The use of mobile devices is increasing in multimedia applications. The multimedia contents are delivered to mobile users over heterogeneous networks. Due to fluctuation in bandwidth and user mobility, the service providers are facing difficulties in providing Quality of Service (QoS) guaranteed delivery for multimedia applications. Multimedia applications depend on QoS parameters such as delay, bandwidth, and jitter to offer better user experience. The existing schemes use the single source and multisource delivery but are unable to balance between stream quality and network congestion for mobile users. We proposed a Quality Oriented Multimedia Content Delivery Scheme (QOMCDS) for the mobile cloud to deliver better quality multimedia contents for the mobile user. The multimedia contents are delivered to the mobile device based on the device's parameters and network environment. The objective video quality assessment models like Peak Signal-to-Noise Ratio (PSNR), Structural Similarity (SSIM), and Video Quality Measurement (VQM) are used to measure the quality of the video. The client side Quality of Experience metric such as Startup delay, Rebuffering events, and Bitrate switch count was used for evaluation. The proposed scheme is evaluated using dash.js and is compared to existing schemes. The results show significant improvement over existing multimedia content delivery schemes.

• Journal of Cadastre & Land InformatiX
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• v.47 no.2
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• pp.145-157
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• 2017

Currently, the height of ships that can pass under Busan Harbor Bridge is limited to 60m or shorter, so that large-sized ships of 60m or taller cannot use Busan Harbor international passenger terminal. Accordingly, this study has developed a service which measures continuously the change of bridge height by water level changes and provides such in real-time for safe bridge passage of large-sized ships of 60m or taller. The measurement system comprised of high-precision laser distance measurement device, GPS sensor, optical module, and damping structure is used to measure the bridge height change according to tide level changes, and the measured information is provided in real-time through cloud-based mobile app. Also, in order to secure objective bridge height data for changes to height limits and navigation supports, the observation data was analyzed and forecast model was drawn. As a result, it became an objective evidence to revise the passage height rules of the Busan Port Bridge from 60 meters to 63 meters.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.4
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• pp.451-465
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• 2003

The major conversion processes of SO$_2$ to sulfate are reactions in gaseous, aqueous phase and on dust surface. Using the measurement data in Ganghwa, the background area of metropolitan Seoul Area, the relative contiribution of the conversion processes are estimated. Generally, aqueous cloud if the most important conversion path followed by dust surface, gas, and aqueous aerosol. Importance of conversion on dust surface increases for the dust storm period. The total conversion rate values over the metropolitan Seoul area are between 1.5 and 8.8$\times$10$^{-11}$ mole m$^{-3}$ air.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.959-961
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• 2003

Cirrus clouds observation was conducted using a lidar system in order to measure their height, thickness and optical depth at Kwangju (35$^{\circ}$10'N, 126$^{\circ}$53'), Korea in winter, December 2002, and spring March and April 2003. Cirrus clouds at high altitude can be distinguished from atmospheric aerosols location by high depolarization ratio and high altitude. Cirrus clouds were observed at 5${\sim}$12km altitudes with a high depolarization ratio from 0.2 to 0.5. Optical depth of cirrus clouds had varied from 0.28 to 1.81. Radiative effect of observed cirrus cloud on climate system was estimated to be negative net flux from ?0.24 to ?31.04 W/m$^{2}$.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.1
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• pp.17-23
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• 2016

This paper presents the implementation of altitude and attitude measurement algorithm using stereo camera for an unmanned aerial vehicle (UAV). Depth images are generated by calibrating the stereo cameras, and converted into 3D point cloud data. By applying a plane fitting algorithm to the resultant point cloud, altitude from ground level, and roll and pitch angles are extracted. To verify the performance, experimental results are provided by comparing with those of the motion caption system.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.367-372
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• 2002

Asian dust aerosol layer of 4-6 km altitude accompanied by low clouds was observed by LIDAR and sky-radiometer in Tokyo urban area on April 10, 2001. To synthesize the top of atmosphere (TOA) reflectance, radiative transfer simulation conducted assuming aerosol/cloud vertical structure and aerosol size distribution that were modeled after the ground observations. The refractive index of Asian dust is derived from a laboratory measurement of sampled Chinese soil particles. The synthesized TOA reflectance is compared to the SeaWiFS-derived one sampled at the low cloud pixels whose airmass is the same as the one passed at the observation site. While the two TOA reflectances compare generally well with few percent difference in reflectance, possible sources of the discrepancy are discussed.

• Journal of Ship and Ocean Technology
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• v.10 no.4
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• pp.34-48
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• 2006

The visual observation of wave condition depends on the observer's skill and experience. Also, the environmental conditions such as light and cloud heavily influence the visual measurement. In the speed test of sea trial, the wave measurement should be objective and accurate. In this paper, the problems of visual measurement and their effects on speed test are described. To overcome those problems, we developed the wave measurement system using commercial marine X-band radar, WaveFinder. The system installed at inland base was calibrated by waverider buoy and then the system's operability was defined. Onboard tests had also been performed three times for formal wave measurement to correct the ship speed. The results illustrated very good agreement with visual observation by experts. It can be concluded that the system would be useful to measure wave and swell information for the sea trial, irrespective of day and night.

• Journal of Advanced Navigation Technology
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• v.24 no.3
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• pp.192-197
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• 2020

Recently, the technologies related to autonomous drive has studying the goal for safe operation and prevent accidents of vehicles. There is radar and camera technologies has used to detect obstacles in these autonomous vehicle research. Now a day, the method for using LiDAR sensor has considering to detect nearby objects and accurately measure the separation distance in the autonomous navigation. It is calculates the distance by recognizing the time differences between the reflected beams and it allows precise distance measurements. But it also has the disadvantage that the recognition rate of object in the atmospheric environment can be reduced. In this paper, point cloud data by triangular functions and Line Regression model are used to implement measurement algorithm, that has improved detecting objects in real time and reduce the error of measuring separation distances based on improved reliability of raw data from LiDAR sensor. It has verified that the range of object detection errors can be improved by using the Python imaging library.