• Journal of the Korean GEO-environmental Society
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• v.14 no.4
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• pp.39-46
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• 2013

Recently, there have been various researches on the cost reduction and savings during the construction activities with the development of automation and computerized information system. Considering the cost savings during the construction, the development of the geological and geotechnical information system with high practical use becomes very important since the geologic and geotechnical data are required for the design of the various structures. Currently, the geological and geotechnical data are collected and distributed as a geological/geotechnical map or engineering geology map and map with other specific purpose through geoinfo system at Korea Institute of Geoscience and Mineral Resources, Korea Mineral Resources GIS at Korea Mineral Resources Corporation, Geotechnical Information Portal System at Korea Institute of Construction Technology, Geotechnical Information System at the City of Seoul and the Ocean Data Integration Material System at Korea Hydrographic and Oceanographic Administration. Furthermore, the information on the groundwater is monitored and collected via Integrated Ground Water Information Service at Korea Water Resources Corporation and Rural Groundwater net at Korea Rural Community Corporation. Therefore, in this study, the contents of the geological and geotechnical data collected from the above mentioned government organization are compared and the DB and distribution system with higher utilization are suggested based on the comparisons with those from other countries such as United States of America, Japan and Germany.

• Korean Journal of Remote Sensing
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• v.24 no.6
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• pp.559-569
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• 2008

The Geostationary Ocean Color Imager (GOCI) on board the Communication Ocean Meteorological Satellite (COMS), the first geostationary ocean color sensor, requires accurate atmospheric correction since its eight bands are also affected by atmospheric constituents such as gases, molecules and atmospheric aerosols. Unlike gases and molecules in the atmosphere, aerosols can interact with sunlight by complex scattering and absorption properties. For the purpose of qualified ocean remote sensing, understanding of aerosol-radiation interactions is needed. In this study, we show micro-physical and optical properties of aerosols using the Optical Property of Aerosol and Cloud (OPAC) aerosol models. Aerosol optical properties, then, were used to analysis the relationship between theoretical satellite measured radiation from radiative transfer calculations and aerosol optical thickness (AOT) under various environments (aerosol type and loadings). It is found that the choice of aerosol type makes little different in AOT retrieval for AOT<0.2. Otherwise AOT differences between true and retrieved increase as AOT increases. Furthermore, the differences between the AOT and angstrom exponent from standard algorithms and this study, and the comparison with ground based sunphotometer observations are investigated. Over the northeast Asian region, these comparisons suggest that spatially averaged mean AOT retrieved from this study is much better than from standard ocean color algorithm. Finally, these results will be useful for aerosol retrieval or atmospheric correction of COMS/GOCI data processing.

• Journal of Broadcast Engineering
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• v.24 no.5
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• pp.879-891
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• 2019

This paper provides performance evaluations of various channel estimation schemes for Advanced Television Systems Committee (ATSC) 3.0 multiple-input multiple-output (MIMO) system under a fixed reception environment. ATSC 3.0 MIMO system can obtain high spectral efficiency and improved reception performance compared to conventional terrestrial broadcasting systems. The ATSC 3.0 MIMO defines Walsh-Hadamard and null pilot encoding algorithms and the amplitude and phase of MIMO pilots are different from those of single-input single-output pilots. At the receiver, linear and discrete Fourier transform (DFT)-based interpolations can be used for the channel estimation. This paper provides the various combinations of the interpolation schemes for channel estimation in time and frequency dimensions, and then analyzes the performance of the various combinations through the computer simulation. The results of computer simulation show that the combination of the linear interpolation in the time dimension and then DFT-based interpolation in the frequency dimension can obtain the best performance among the considered combinations.

• Journal of the Korea Convergence Society
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• v.12 no.9
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• pp.11-19
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• 2021

A software system is required to change during its life cycle due to various requirements such as adding functionalities, fixing bugs, and adjusting to new computing environments. Such program code modification should be considered as carefully as a new system development becase unexpected software errors could be introduced. In addition, when reusing open source programs, we can expect higher quality software if code changes of the open source program are predicted in advance. This paper proposes a Convolutional Neural Network (CNN)-based deep learning model to predict source code changes. In this paper, the prediction of code changes is considered as a kind of a binary classification problem in deep learning and labeled datasets are used for supervised learning. Java projects and code change logs are collected from GitHub for training and testing datasets. Software metrics are computed from the collected Java source code and they are used as input data for the proposed model to detect code changes. The performance of the proposed model has been measured by using evaluation metrics such as precision, recall, F1-score, and accuracy. The experimental results show the proposed CNN model has achieved 95% in terms of F1-Score and outperformed the multilayer percept-based DNN model whose F1-Score is 92%.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.874-881
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• 2022

Until 2016, before discussions on the restoration of brackish water of the Nakdong River Estuary started in earnest, the downstream water level was predicted using the data of existing tide level observatories (Busan and Gadeokdo) several kilometers away from the estuary. However, it was not easy to carry out the prediction due to the dif erence in tide level and phase. Therefore, this study was conducted to estimate tide prediction more accurately through tidal harmonic analysis using the measured water level affected by the tides in the offshore waters adjacent to the Nakdong River Estuary. As a research method, the storage status of observation data according to the period and abnormal data were checked at 10-minute intervals in the offshore sea area near the Nakdong River Estuary bank, and the observed and predicted tides were measured using TASK2000 (Tidal Analysis Software Kit) Package, a tidal harmonic analysis program. Regression analysis based on one-to-one comparison showed that the correlation between the two components was high correlation coef icient 0.9334. In predicting the tides for the current year, if possible, more accurate data can be obtained by harmonically analyzing one-year tide observation data from the previous year and performing tide prediction using the obtained harmonic constant. Based on this method, the predicted tide for 2022 was generated and it is being used in the calculation of seawater inflow for the restoration of brackish water of the Nakdong River Estuary.

• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.146-154
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• 2024

The ship management industry in South Korea has been growing steadily, leading the government to implement policies to support its development in response to changing environmental conditions. These policies aim to improve the competitiveness of South Korea's ship management industry by recognizing the importance of skilled professionals in determining its success. Plans and policies have been put in place to cultivate these professionals, but ship management companies are currently facing a serious shortage of manpower. To enhance the industry's competitiveness, it is essential to attract and retain competent ship management professionals. Therefore, this study investigates the reasons for turnover among these professionals. The research results identified four factors contributing to turnover: Work Environment, Economic Compensation and Welfare Benefits, Self-Development, and Promotion and Career Advancement. Subsequent multiple regression analysis based on these factors revealed the need to strengthen economic rewards and benefits in order to reduce turnover rates among ship management professionals. This study provides foundational data for the development of stable human resource management policies for the future of the ship management industry.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.1
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• pp.51-61
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• 2019

Computing the sea level slope at the BM(Bench Mark) in the coast areas around the Korean Peninsula is important for establishing height of BM of the Korean geodetic leveling network. In this study, MSL(Mean Sea Level) was recalculated with the long-term tide observation data based on the IHO(International Hydrographic Organization) standard(18.6 years), and the BM height was reanalyzed by precision leveling. The sea surface topography was analyzed by leveling at Mokpo(Mokpo Starting Point), Busan (09-00-00) and Mukho(20-26-00) BMs, and the sea level slope was computed based on the Korean vertical origin point. As a result of this study, the sea level slope of the west and east coasts between Incheon(-2.27cm) and Mukho(17.56cm) located at $37.5^{\circ}N$ was analyzed as 19.83cm. Domestic geodesists and oceanologists have confronted each other with regard to the issue of latitudinal changes in long term MSL. In the west coast, the Mokpo is 1.12cm higher than Incheon, and the Busan is 2.18cm higher than Mukho. Therefore, the west and east coasts have been analyzed as sea level slope rising to the south. It can be used to solve the reestablishment of the Korean geodetic leveling network and the problem of the elevation discrepancy in the BM.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5B
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• pp.497-507
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• 2010

Climate changes affect greatly natural ecosystem, human social and economic system acting on constituting the climate system such as air, ocean, life, glacier and land, etc. and estimating the current impact of climate change would be the most important thing to adapt to the climate changes. This study set the target area to Nakdong river watershed and investigated the impact of climate changes through analyzing precipitation tendency, and to understand the impact of climate changes on hydrological elements, analyzed elasticity of precipitation-streamflow. For the analysis of precipitation trend, collecting the precipitation data of the National Weather Service from major points of Nakdong river watershed, resampling them at the units of year, season and month, used as the data of precipitation trend analysis. To analyze precipitation-streamflow elasticity, collecting area average precipitation and long-term streamflow data provided by WAMIS, annual and seasonal time-series were analyzed. In addition, The results of this study and elasticity, and other abroad study compared with the elasticity analysis and the validity of this study was verified. Results of this study will be able to be utilized for study on a plan to increase of flood control ability of flooding constructs caused by the increase of streamflow around Nakdong river watershed due to climate changes and on a plan of adapting to water environment according to climate changes.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.11
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• pp.503-510
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• 2014

With the development of electronic communication technology, the ship's navigational equipment is being digitized, and it has being studied touch-screen-based navigation user interface. However, due to the influence of environmental factors such as waves, it has a potential problem hazardous marine accident occurs due to incorrect operation, the systematic research in consideration of this be done do not. In this paper, we provide a user interface experimental model to verify the stability that takes into account the external environment of the touch-screen input on. Further, we simulated to verify that the interface of the touch screen, the effect of applying the input delay time and the size of the button is obtained through the experimental model proposed. It will be able to greatly contribute to studies of the interface robust touch screen user errors that can be analyzed by the experimental model is proposed to improve the ship, the overall system stability.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.1
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• pp.9-16
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• 2010

The purpose of this study is to clarify the origin of organic matters on sediment and the characteristics of seasonal variation at an estuarine tidal flat. Silt-clay content (<63 ${\mu}m$), chlorophyll a, TOC, C/N ratio and the stable isotope ratio of carbon and nitrogen were measured at tidal flat around the estuary of the Nanakita River. As a result, organic matters originating from marine organic matter and bethic microalgae greatly contributed to sedimentation of organic matters at Stn.A, sandy tidal flat, though terrigenous organic matters did at Stn.C, muddy tidal flat. Furthermore, it was revealed that the volume and origin of organic matters in the sediments depended on seasonal variation, and the factors were different from the Stns, i.e. bentic microalgae and event for Stn.A, and the eventual sedimentation of organic matters originating from terrestrial plants, respectively.