• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.1031-1039
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• 2016

The Quasi-Zenith Satellite System(QZSS) is the Japanese satellite navigation system, which designs to increase the GPS system's visibility in the urban areas. The first satellite(Michibiki) was launched in 2010 and started to broadcast navigation signals. Therefore, the purpose of the research is to analyze the performance of GPS and QZSS based on the advantage of the integrated GNSS. Especially, the study has been processed in terms of improving satellite navigation parameters around Korean Peninsula. To do this, there have been the comprehensive analysis of the QZSS characteristics, the experimental test, and its statistical analysis for realizing advantage of GPS and QZSS. Through these systemic steps, it was recognized that the integrated GPS and QZSS has more reliable than GPS in case of not only limited visibility but also ordinary positioning. Additionally, the integrated GPS and QZSS would be very useful to improve the various navigation parameters around the peninsula.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.493-505
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• 2020

Food web structures in the lower trophic levels of the seas around the Korean peninsula were investigated in August 2019 using stable isotopes. There were variable ratios of the carbon (-26.18 ~ -20.61 ‰) and nitrogen stable (5.36 ~ 15.20 ‰) isotopes in the particulate organic matter (POM). Most of the organisms ingested micro-POM as a major food source, but this varied spatially. The chaetognaths (3.40 ± 0.61) occupied the highest trophic level. The isotope mixing model showed that the proportions (13 ~ 51 %) of some organisms (i.e., copepods and euphausiids) reflected the relative contributions as major food sources for chaetognaths at each site.

• Journal of Advanced Navigation Technology
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• v.17 no.4
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• pp.396-403
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• 2013

Recently, GNSS users can utilize various navigation satellite thanks to GPS modernization, renewal of GLONASS, and development of Galileo and Beidou. And availability performance of users is expected to be improved because these new navigation satellites transmit L5 signal as well as L1 signal, and users can directly estimate the ionospheric delays. In accordance with these changes existing Satellite Based Augmentation System (SBAS) which considers only GPS L1 signal is being developed to support dual frequency and multi-constellation GNSS users. This paper describes the main features of dual-frequency, multi-constellation SBAS algorithms and estimates the performance in Korean region by simulation.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.261-266
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• 2005

According to development of satellite geodesy, gravity potential models which have high accuracy and resolution were released. Using the EIGEN-CG01C model based on low orbit satellite data such as CHAMP and GRACE and the EGM96 model, geoid and gravity anomaly were calculated and compared. The study area is located at $123^{\circ}{\sim}132^{\circ}$ E, $33^{\circ}{\sim}43^{\circ}$ including Korea. Comparing two models, very high correlation more than 0.90 in geoid and gravity anomaly was observed, but in amplitude analysis the EIGEN-CG01C model have higher amplitude in high frequency area. Gravity anomaly calculated with both models shows a little difference in North Korea and some coast area of the Yellow sea. Through power spectrum analysis, residual anomaly that can be used in large scale structure or underground resources survey was calculated.

• Journal of the Korean Geographical Society
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• v.45 no.3
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• pp.319-341
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• 2010

The purposes of this study are to classify heavy snowfall types in the Republic of Korea based on fresh snowfall data and atmospheric circulation data during the last 36(1973/74-2008/09) snow seasons and to identify typical surface synoptic climate patterns that characterize each heavy snowfall type. Four synoptic climate categories and seventeen regional heavy snowfall types are classified based on sea level pressure/surface wind vector patterns in East Asia and frequent spatial clustering patterns of heavy snowfall in the Republic of Korea, respectively. Composite analyses of multiple surface synoptic weather charts demonstrate that the locations and intensity of pressure/wind vector mean and anomaly cores in East Asia differentiate each regional heavy snowfall type in Korea. These differences in synoptic climatic fields are primarily associated with the surge of the Siberian high pressure system and the appearance of low pressure systems over the Korean Peninsula. In terms of hemispheric atmospheric circulation, synoptic climatic patterns in the negative mode of winter Arctic Oscillation (AO) are also associated with frequent heavy snowfall in the Republic of Korea at seasonal scales. These results from long-term synoptic climatic data could contribute to improvement of short-range or seasonal prediction of regional heavy snowfall.

• Journal of the Korean Geotechnical Society
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• v.18 no.2
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• pp.65-74
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• 2002

The measurement of in-situ stress is essential to estimate the ground displacement and the stress distribution of a tunnel and an underground structure. In this study, the in-situ stress distribution of the Southern Korean peninsula was re-evaluated by the new 380 in-situ data which were determined by overcoring and hydrofracturing methods, and the three-din erosional numerical analysis of tunnelling was performed. The results of in-situ stress distribution show that the distribution of horizontal stress tends to be more irregular in metamorphosed(gneiss) and granite areas than in sedimentary and volcanic areas. The ratio of horizontal to vertical stresses(K-value) in volcanic area is less than 1 below the depth of 150m. The direction and magnitude of three dimensional in-situ stresses were shown simultaneously in a figure for the first time in Korea. The three-dimensional numerical analysis of tunnelling indicates that the orientation and magnitude of displacement around a tunnel are controlled mainly by the difference between the maximum and minimum horizontal stresses.

• Journal of the Korean earth science society
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• v.36 no.7
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• pp.649-660
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• 2015

This study aimed at the correlation analysis of geomagnetic variations related to earthquakes which occurred in and around the Korean Peninsula from 2012 to 2014. The wavelet-based semblance technique was used to confirm the geomagnetic variations related to earthquakes. As a result, a pattern of consistent geomagnetic variations in total magnetic has been found from the earthquakes occurred within 100 km radius around the observation site. A similar correlation between earthquake location and Z-field geomagnetic data was also confirmed by the wavelet-based semblance analysis. We mainly used the high quality geomagnetic measurements from the Cheongyang Observatory and additionally used the data from the Bohyunsan Observatory in order to validate the correlation between earthquake and Z-field geomagnetic data.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.1
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• pp.47-54
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• 2015

In this study, we developed strategies for pre-processing GNSS data for the purpose of separating geodetic factors from crustal deformation due to the earthquakes. Before interpreting GNSS data analysis results, we removed false signals from GNSS coordinate time series. Because permanent GNSS stations are located on a large tectonic plate, GNSS position estimates should be affected by the tectonic velocity of the plate. Also, stations with surrounding trees have seasonal signals in their three-dimensional coordinate estimates. Thus, we have estimated the location of an Euler pole and angular velocities to deduce the plate tectonic velocity and verified with geological models. Also, annual amplitudes and initial phases were estimated to get rid of those false annual signals showing up in the time series. By considering the two effects, truly geodetic analysis was possible and the result was used as preliminary data for analyzing post-seismic deformation of the Korean peninsula due to the Tohoku-oki earthquake.

• Korean Journal of Environment and Ecology
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• v.21 no.2
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• pp.107-112
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• 2007

This study was carried out to investigate the herpeto-fauna at Hallasan National Park. We conducted a survey at 1100 Resting places, Eoseungsaengak, Donnaeko, Eorimok, Yeongsil, Gwaneumsa and Seongpanak from April, 2006 to January, 2007. A series of four families and 5 species of amphibians and 4 families and 8 species of reptiles were observed. Amphiesma vibakari ruthveni, Takydromus wolteri, Scincella vandenburghi, Coluber spinalis and Hynobius quelpartensis which are rarely appearing inland but they were frequently observed by this survey. Also, we observed Sibynophis chinensis that only inhabits Jeju island with in Korea. Jeju island has both southern and northern boundary lines for amphibians and reptiles. Amphibians and reptiles in Jeju island have a different from those inland and valuable information for biogeograpy due to dissimilar climate and isolation from continental for a long time. It is not certain whether some amphibians and reptiles, Bufo gargarizans, Rana rugosa, R. plancyi, Elaphe rufodorsata and Takydromus amurensis, inhabit Jeju island, as recorded in previous literatures, so the research on current status of them has to be carried out immediately.

• Convergence Security Journal
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• v.18 no.2
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• pp.77-88
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• 2018

The purposes of this paper are to research the military utilization of weather modification techniques and to induce their research priority when considering the Korean Peninsular environment and technical level. To achieve these goals, the advantages and disadvantages of weather modification technologies have been discussed, and the evaluation index evaluation was derived through the Delphi method, and the weight of the evaluation index and the final research priority were induced through analytic hierarchical process. Analysis shows that the ionospheric modulation technology has the highest priority in terms of effectiveness as a weapon system and compatibility in the Korean Peninsula environment. It is expected that Korean ionosphere modification can disturb C4ISR function of the enemy and guarantee ours reliably when operating PGM, military satellite, surveillance & reconnaissance equipments, etc. Other weather modification technologies except for ionosphere modification should be developed gradually in that potential threat can be expanded to neighboring countries after the Unification of the Korea.