• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.423-432
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• 2016

Due to the increase in the number of transfer lines and ground level connections with mixed-use high-rise buildings, the Seoul Metro suffers from loaded signage fatigue because of the presence of too many signs. The purpose of this research is to propose ways of improving the wayfinding on the Seoul subway station by examining the signage and (applying the) universal design (UD) concept. A review of the literature explored five universal design components, viz. the accessibility, safety, equitability, perception, and aesthetics. The field investigation found that the ceiling and wall type and general information boards were high on the information hierarchy. The survey respondents merely perceived universal design concept, however, most needed principle. The IPA found that the signs should be appropriately laid out, spaced and located from the perspective of accessibility, and their unity and harmony were other aspects that could be improved while general information boards should include important landmarks outside. In conclusion, this study suggests that the universal design signage concept should be applied to every station and that specific stations should have a duly sign system.

• Korean Journal of Remote Sensing
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• v.39 no.5_1
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• pp.467-479
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• 2023

Satellite altimeters have continuously observed sea surface height (SSH) in the global ocean for the past 30 years, providing clear evidence of the rise in global mean sea level based on observational data. Accurate altimeter-observed SSH is essential to study the spatial and temporal variability of SSH in regional seas. In this study, we used measurements from the Ieodo Ocean Research Station (IORS) and validate SSHs observed by satellite altimeters (Envisat, Jason-1, Jason-2, SARAL, Jason-3, and Sentinel-3A/B). Bias and root mean square error of SSH for each satellite ranged from 1.58 to 4.69 cm and 6.33 to 9.67 cm, respectively. As the matchup distance between satellite ground tracks and the IORS increased, the error of satellite SSHs significantly amplified. In order to validate the correction of the tide and atmospheric effect of the satellite data, the tide was estimated using harmonic analysis, and inverse barometer effect was calculated using atmospheric pressure data at the IORS. To achieve accurate tidal corrections for satellite SSH data in the seas around the Korean Peninsula, it was confirmed that improving the accuracy of tide data used in satellites is necessary.

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.1
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• pp.37-44
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• 1985

With a view to producing forest trees and forages, the grassland development in the forest has become an important issue in Korea. For better grassland development in the forest, a field research was carried out to investigate the effects of 3 dominant types of seed mixtures (orchardgrass type, tall fescue type, and reed canarygrass type) on the botanical composition, pasture plants composition and dry matter yield of grass-clover mixtures grown under pine trees (shading level; about 50%). As a preliminary test, 3 shading levels (o; full sunlight, 50, and 60%) were treated to compare the yield of pasture in the forest. This experiment was arranged as a randomized block design with 3 replications, and performed at the experimental field in the suburban forest of Suweon, during 1982 to 1984. The results obtained are summarized as follows: 1. As the shading level increases by 0, 50, and 6075, the dry matter yield of forage was decreased by 100 (11.13 ton/ha),81 and 76%, respectively. 2. The total ground cover and percentage of pasture plants were decreased by year, regardless of 3 different dominant types of pasture mixtures. The wild grasses and shrubs, however, tended to be increased by year. 3. Orchardgrass was found to be the only dominant grass showing 80% of all pasture plants, regardless of 3 types of pasture mixtures. But the percentage of tall fescue, reed canarygrass, Kentucky bluegrass and ladino clover were low. 4. Dry matter yield was rapidly decreased to 5075 in the second harvest year, 1984 compared with that of the first harvest year, 1983. In 1983, the yield of orchardgrass type, tall fescue type, and reed canary-grass type was 8.95, 9.05, and 7.93 ton per ha, respectively, while in 1984, the yield was 4.66, 4.57, and 4.38 ton per ha, respectively. 5. From the above results, it is suggested that tile orchardgrass dominant type of pasture mixtures is the most desirable considering forage production and botanical composition, and maintaining productivity for several years is important in the grassland under the trees.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.4
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• pp.393-403
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• 2011

In this study, we suggested the period of tide observations is proper to calculate the mean sea level(MSL) precisely on Incheon tide station using wavelet analysis, and newly determined then the vertical reference surface of Korea using the calculated MSL. In order to calculate the height difference between the calculated MSL and specific ground station (ICGP) near the Incheon tide stations, we performed the laser measurements directly to the sea surface where located below ICGP. The orthometric-height of ICGP was determined that corrected the height difference to the calculated MSL using linear interpolation method. Finally, we connected the orthometric-height of ICGP with the original benchmark (ORBM) using GPS leveling methods for determining the new orthometric-height of ORBM. As the results, there is a variation amount of 0.026m between the new MSL was calculated in this study and old MSL was calculated in 1910's. Also, there is a difference of 0.035m between the new and old orthometric-heights of ORBM. The connection (or leveling) error of 0.009m was revealed in new orthometric height of ORBM with consideration of MSL variation which may caused by the error of GPS ellipsoid height and/or geoid model. In this study, we could be determined precisely the orthometric-height of ORBM based on the new MSL of Incheon Bay using only GPS leveling method, not a spirit leveling method. Therefore, it is necessary to determine the vertical datum strictly using long-term and continuously tide observations more than 19 years and to use the GPS leveling method widely in the height leveling work for the effective changeover from the orthonormal to the orthometric in national height system.

• Korean Journal of Remote Sensing
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• v.38 no.2
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• pp.167-177
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• 2022

In order to obtain satellite image products using the image transmitted to the ground station after capturing the satellite images, many image pre/post-processing steps are involved. During the pre/post-processing, when converting from level 1R images to level 1G images, geometric correction is essential. An interpolation method necessary for geometric correction is inevitably used, and the quality of the level 1G images is determined according to the accuracy of the interpolation method. Also, it is crucial to speed up the interpolation algorithm by the level processor. In this paper, we proposed a lightweight CNN-based interpolation method required for geometric correction when converting from level 1R to level 1G. The proposed method doubles the resolution of satellite images and constructs a deep learning network with a lightweight deep convolutional neural network for fast processing speed. In addition, a feature map fusion method capable of improving the image quality of multispectral (MS) bands using panchromatic (PAN) band information was proposed. The images obtained through the proposed interpolation method improved by about 0.4 dB for the PAN image and about 4.9 dB for the MS image in the quantitative peak signal-to-noise ratio (PSNR) index compared to the existing deep learning-based interpolation methods. In addition, it was confirmed that the time required to acquire an image that is twice the resolution of the 36,500×36,500 input image based on the PAN image size is improved by about 1.6 times compared to the existing deep learning-based interpolation method.

• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1049-1057
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• 2020

This study aimed to develop a flow measurement method using drone in flood season. Measuring flow in all branches is difficult to conduct annually due to budget and labor limitation, safety and river works. Especially when heavy rain like storm comes, changes in stage-discharge relationship should be reviewed; however, it is usually impeded by the aforementioned issues. To solve the problem, it developed a simple measuring method with a minimum of labor and time. A numeric map and numeric orthophoto coordinate of South Korea are mostly based on Transverse Mercator Projection (TM) in accordance with rectangular coordinate system and use World Geodetic Reference System 1980 (GRS80) oval figure for conversion. Applying a concept of aerial photogrammetry, it located four visible Ground Control Points (GCP) near the river at Uijeongbu-si (Singok Bridge) and Yeongdong-gun (Youngdong 2nd Bridge) station and measured the coordinates using VRS DGPS. Hovering at a same level, drones took orthophoto of water surface at an interval of 3 seconds. It defined the pictures with GRS80 TM coordinate system, a rectangular coordinate system and then conducted an orthometric correction using GCP coordinates. According to X and Y coordinate analysis, it estimated the distance between the floating positions at 3 seconds-intervals and calculated the flow through the flow area according to the flow path. This study attested applicability of the flow measurement method using drone in flood season by applying the rectangular coordinate system based on the concept of aerial photogrammetry.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.306-314
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• 2018

A two-axis gimbal-type X-band antenna for CAS(Compact Advanced Satellite) transmits large amount of image data to ground station regardless of satellite attitude and orbital motion. This antenna mounted on the external surface of the satellite is directly exposed to the extreme space with thermal environment during the orbital operation. Therefore, a proper thermal design is needed to maintain the antenna itself as well as other main components within allowable temperature range. In this study, the thermal design effectiveness of two-axis gimbal X-band antenna was verified through the thermal analysis. In addition, required power and duty cycle of heater were estimated through the thermal analysis under conditions of system level thermal vacuum test and on-orbit thermal environment. The thermal analysis results indicated that all the main components of X-band antenna satisfy the allowable temperature requirement.

• Korean Journal of Geomatics
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• v.3 no.1
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• pp.73-79
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• 2003

To manage national territory and cadastral data efficiently, accuracy and cost-efficiency in cadastral boundary surveying is inevitable. The efficient management of cadastral data is a very important element in national land management. Survey techniques are being introduced. Recently, improvements in survey techniques have been made with the development of satellite surveying, Allowing accurate and fast surveys. If we can calculate the output accurately in real-time in survey fields, it will open a new method in cadastral detail surveying. According to the classification on Law of cadastral surveying, Cadastral surveying can be divided into cadastral control point surveying and cadastral detail surveying. The control point survey can be divided into cadastral triangulation surveying and cadastral traverse surveying. The detailed survey is usually perform by plane surveying. Among these, cadastral detail surveying will be reviewed in this study. In this study, the combination of the satellites, such as US managed GPS and Russian managed GLONASS was used. In the satellite survey in downtown, data interruption symptoms arose(according to the mask angle of the satellite). Therefore; we combined the satellites to get date more accurately. A block of Haewoondae New City in Busan, Korea, which has Numerical Cadastral Law was selected as the sample area for this study. Block II and III are surrounded by high rise apartments. One side of Block I and IV is level ground and the other side is full of high rise apartments. Especially, Block II is surrounded by high rise apartment houses with 20 meters width. In the results of the study Block II did not satisfy the allowable precision, while Block I, II and IV satisfied the allowable precision of the enforcement regulations of Cadastral Law. Therefore, it is judged that the traditionally used Total Station method should be used for supplementary survey on Block II, in stead.

• Smart Structures and Systems
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• v.7 no.2
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• pp.83-102
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• 2011

As a testbed for various structural health monitoring (SHM) technologies, a super-tall structure - the 610 m-tall Guangzhou Television and Sightseeing Tower (GTST) in southern China - is currently under construction. This study aims to explore state-of-the-art wireless sensing technologies for monitoring the ambient vibration of such a super-tall structure during construction. The very nature of wireless sensing frees the system from the need for extensive cabling and renders the system suitable for use on construction sites where conditions continuously change. On the other hand, unique technical hurdles exist when deploying wireless sensors in real-life structural monitoring applications. For example, the low-frequency and low-amplitude ambient vibration of the GTST poses significant challenges to sensor signal conditioning and digitization. Reliable wireless transmission over long distances is another technical challenge when utilized in such a super-tall structure. In this study, wireless sensing measurements are conducted at multiple heights of the GTST tower. Data transmission between a wireless sensing device installed at the upper levels of the tower and a base station located at the ground level (a distance that exceeds 443 m) is implemented. To verify the quality of the wireless measurements, the wireless data is compared with data collected by a conventional cable-based monitoring system. This preliminary study demonstrates that wireless sensing technologies have the capability of monitoring the low-amplitude and low-frequency ambient vibration of a super-tall and slender structure like the GTST.

• Journal of Astronomy and Space Sciences
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• v.34 no.2
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• pp.139-151
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• 2017

This paper presents an overview of deep space orbit determination software (DSODS), as well as validation and verification results on its event prediction capabilities. DSODS was developed in the MATLAB object-oriented programming environment to support the Korea Pathfinder Lunar Orbiter (KPLO) mission. DSODS has three major capabilities: celestial event prediction for spacecraft, orbit determination with deep space network (DSN) tracking data, and DSN tracking data simulation. To achieve its functionality requirements, DSODS consists of four modules: orbit propagation (OP), event prediction (EP), data simulation (DS), and orbit determination (OD) modules. This paper explains the highest-level data flows between modules in event prediction, orbit determination, and tracking data simulation processes. Furthermore, to address the event prediction capability of DSODS, this paper introduces OP and EP modules. The role of the OP module is to handle time and coordinate system conversions, to propagate spacecraft trajectories, and to handle the ephemerides of spacecraft and celestial bodies. Currently, the OP module utilizes the General Mission Analysis Tool (GMAT) as a third-party software component for high-fidelity deep space propagation, as well as time and coordinate system conversions. The role of the EP module is to predict celestial events, including eclipses, and ground station visibilities, and this paper presents the functionality requirements of the EP module. The validation and verification results show that, for most cases, event prediction errors were less than 10 millisec when compared with flight proven mission analysis tools such as GMAT and Systems Tool Kit (STK). Thus, we conclude that DSODS is capable of predicting events for the KPLO in real mission applications.