• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1463-1478
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• 2022

Maritime transport accounts for 99.7% of the exports and imports of the Republic of Korea; therefore, developing a vessel monitoring system for efficient operation is of significant interest. Several studies have focused on tracking and monitoring vessel movements based on automatic identification system (AIS) data; however, ships without AIS have limited monitoring and tracking ability. High-resolution optical satellite images can provide the missing layer of information in AIS-based monitoring systems because they can identify non-AIS vessels and small ships over a wide range. Therefore, it is necessary to investigate vessel monitoring and small vessel classification systems using high-resolution optical satellite images. This study examined the possibility of developing ship monitoring systems using Compact Advanced Satellite 500-1 (CAS500-1) satellite images by first training a deep learning model using satellite image data and then performing detection in other images. To determine the effectiveness of the proposed method, the learning data was acquired from ships in the Yellow Sea and its major ports, and the detection model was established using the You Only Look Once (YOLO) algorithm. The ship detection performance was evaluated for a domestic and an international port. The results obtained using the detection model in ships in the anchorage and berth areas were compared with the ship classification information obtained using AIS, and an accuracy of 85.5% and 70% was achieved using domestic and international classification models, respectively. The results indicate that high-resolution satellite images can be used in mooring ships for vessel monitoring. The developed approach can potentially be used in vessel tracking and monitoring systems at major ports around the world if the accuracy of the detection model is improved through continuous learning data construction.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.6
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• pp.397-404
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• 2014

In Korea, harbor tranquility is generally estimated by using both methods of investigating harbor calmness under abnormal wave condition and evaluating the harbor serviceability. The efficiency of the former method is questionable as the tranquility of a harbor is judged by a wave height criterion that is arbitrarily determined without rational basis. In case of the latter method, the utilization rate of a harbor is estimated by using the exceedance probability of wave height or the distribution of wave heights and periods that is obtained from longterm measured or hindcasted wave data. Use of long-term data is desirable in order to guarantee the accuracy of the exceedance probability. Meanwhile, the criterion for determining maximum allowable wave height for cargo handling works is too simple and has limitations for being used in an actual field condition. Problems of existing method for estimating harbor tranquility were verified by the wave observation data in Busan New Port. And the importance of the field observation data was emphasized. It is necessary to perform long-term wave monitoring inside and outside of major ports in Korea in order to establish more advanced standard for evaluating harbor tranquility based on such observed wave data.

• The Journal of Industrial Distribution & Business
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• v.10 no.5
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• pp.67-76
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• 2019

Purpose - The Korean child welfare services may have different feelings between providers and users. Few studies on the child welfare service quality have been conducted and research on the coorientation model of child welfare services are nonexistent. We compared the perceptions of Korean child welfare service providers and users in this study. It will have many applications in the service quality fields by applying a coorientation model. Research design, data, and methodology - In order to enhance user satisfaction with child welfare services, around 200 samples were carried out both in Busan and Kyungsangnamdo randomly. Seven point Likert scale was used in the questionnaire. Two measurements were made to evaluate the different positions on the part of child welfare service providers and users to assess their mutual orientation. Paired t-test verification was conducted for congruency analysis, and the verification of agreement and accuracy was analyzed by independent t-tests. Results - We empirically examined the differences between the providers and the users stance. The results are as follows. We have verified the statistical significance of the difference in perception between providers and users. We also confirmed a degree of agreement, a degree of congruency, a degree of accuracy and a degree of meta agreement in the study. In the Korean child welfare service quality, the coorientation model of process quality appeared in the form of semi-dissensus, the coorientation model of results quality were shown in the form of ignorances and the coorientation model of physical environment quality were investigated in the form of semi-dissensus. Conclusion - The study concluded that users need to understand more about the providers in order to enhance the coorientation model in process quality and physical environmental quality, and the providers need to persuade the users clearly about the positive factors. To enhance the coorientation model of the result quality, it can be misunderstood by guessing that the other party will positively evaluate it. Therefore, users believe that they need to talk more clearly to the provider about the results of the korean child welfare service quality to reduce misunderstandings and to understand each other about the resulting quality.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.67-73
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• 2021

The purpose of this study is to obtain a safe area for a passing vessel between anchored vessels by developing a model to predict the collision risk, frequent collisions occur between the anchored vessel and the passing vessel through the anchorage. For this, this study selected the southern anchorage of Busan port, which is the largest harbor in Korea, as the target area and extracted and analyzed VTS (Vessel Traffic Service) data during the period in which anchored vessels were the most waited. The ratio of D/L for each bearing was obtained to determine the safe distance (D) passes based on the length (L) of the passing vessel between anchored vessels. Based on the average domain of the D/L ratio distribution, the percentage of anchored vessels within the scope of the pre-studied ship's domain was analyzed to obtain a domain reflecting the degree of risk of VTSOs. Further research will evaluate and analyze the collision risk of a passing vessel using Domain-watch, the minimum safe distance between anchored vessels, and the safe domain of a passing vessel through anchorage, to develop a model for VTS to manage anchorages more efficiently and safely.

• Journal of the Korean Geosynthetics Society
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• v.22 no.1
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• pp.87-96
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• 2023

There are a lot of difference between the surface settlement and the differential settlement measured at the Busan New Port, where the dredged and reclaimed clay layer exists and below the clay is originally thickly distributed. To find the cause and solution of this, the actual conditions of each differential settlement used for the soft ground improvement, characteristics, installation method, measurement frequency, measurement data management, and data analysis of each type were considered. In the deep soft ground improvement work where large deformation occurs, the bending deformation of the screw-type differential settlement gauge is less than that of other types of measuring instruments, so there is less risk of loss, and the reliability of data is relatively high as the instruments are installed by drilling for each stratum. Since the greater the amount of high-precision settlement measurement data, the higher the settlement analysis precision. It is necessary to manage with higher criteria than the measurement frequency suggested in the standard specification. For the data management of the differential settlement gauge, it is desirable to create graphs of the settlement and embankment height of the relevant section over time, such as surface, differential, and settlement of pore water pressure gauge for each point. In the case of multi-layered ground with different compression characteristics, it is more appropriate to perform settlement analysis by calculating the consolidation characteristics of each stratum using a differential settlement data.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.3
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• pp.128-137
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• 2013

Due to the global warming and air pollution, interest in renewable energies has increased in recent years. In particular, the crisis of the depletion of fossil energy resources in the near future has accelerated the renewable energy technologies. Among the renewable energy resources, oceans covering almost three-fourths of earth's surface have an enormous amount of energy. For this reason, various approaches have been made to harness the tremendous energy potential. In order to achieve two purposes: to improve harbor water quality and to use wave energy, this study proposed a sea water exchange structure applying an Oscillating Water Column (OWC) wave generation system that utilizes the air flow velocity induced by the vertical motion of water column in the air chamber as a driving force of turbine. In particular, the airflow velocity in the air chamber was estimated from the time variations of water surface profile computed by using 3D-NIT model based on the 3-dimensional irregular numerical wave tank. The relationship of the frequency spectrums between the computed airflow velocities and the incident waves was analyzed. This study also discussed the characteristics of frequency spectrums in the air chamber according to the presence of the structure, wave deformations by the structure, and the power of the water and air flows were also investigated. It is found that the phase difference exists in the time series data of water level fluctuations and air flow in the air chamber and the air flow power is superior to the fluid flow power.

• International Commerce and Information Review
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• v.18 no.3
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• pp.47-72
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• 2016

The Government of Korea has always focused on developing and maintaining a surplus on the balance of payments as a successful trade policy. The focus should now be on spatial information hiding, revealing patterns in trade activities that enable viewing trade in a more sophisticated manner. This study utilizes trade statistical data such as the United States-South Korea imports and exports from 2003 to 2015 officially released by the two countries. It allows us to analyze and extract the spatial information pertaining to the origin, transit, and destination. First, in the case of export data to the United States, the origin of the trade goods has expanded and decentralized from the metropolitan area. With regard to transit, in 2003, most of the exported goods were shipped by ocean vessels and arrived at the ports on the western coast of the United States. However, trade patterns have changed over the 12-year period and now more of that trade has moved to the southern ports of the United States. In terms of destination, California and Texas were importing goods from South Korea. With the development of the automotive industry in Georgia and Alabama, these two states also imported huge volumes of automobile parts. Second, in case of import data, most imported goods from the United States originated from California and Texas. In this case, 40% of goods were shipped by air freight and arrived at the Incheon-Seoul International Airport; most ocean freight was handled at the Port of Busan. The purpose of this study is to decompose the spatial information from the trade statistics data between Korea and the United States and to depict visualized bilateral trade structure by origin, transit, and destination.

• Proceedings of KOSOMES biannual meeting
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• 2007.05a
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• pp.15-20
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• 2007

In this study, the authors investigated the change of marine environment by dumping dredged materials generated by construction of Busan New Port. There are lots of possibilities to impact an ocean ecosystem by toxic materials in the dredged material dumped in the open seas. As a result of analysis of environmental monitoring in the study areas 12 times a year, COD is II grade, T-N is I grade, T-P is between II and III grade. This result is same as another results of offshore in Korea. It seems unclear that it results from the change of water quality by dumping dredged material. However, according to the result of this investigation, it is not effected extensively to the marine environment by dumping dredged materials. We need further environmental monitoring in the interest sea areas, also need to keep on investigating the impact on the marine ecosystem by dumping dredged materials.

• Journal of the Korean Geotechnical Society
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• v.22 no.12
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• pp.67-76
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• 2006

The reasonable assessment of the shear stiffness of a dredged soft ground and soft clay is difficult due to the soil disturbance. This study addresses the development and application of a new in-situ shear wave measuring apparatus (field velocity probe: FVP), which overcomes several of the limitations of conventional methods. Design concerns of this new apparatus include the disturbance of soils, cross-talking between transducers, electromagnetic coupling between cables, self acoustic insulation, the constant travel distance of S-wave, the rotation of the transducer, directly transmitted wave through a frame from transducer to transducer, and protection of the transducer and the cable. These concerns are effectively eliminated by continuous improvements through performing field and laboratory tests. The shear wave velocity of the FVP is simply calculated, without any inversion process, by using the travel distance and the first arrival time. The developed FVP Is tested in soil up to 30m in depth. The experimental results show that the FVP can produce every detailed shear wave velocity profiles in sand and clay layers. In addition, the shear wave velocity at the tested site correlates well with the cone tip resistance. This study suggests that the FVP may be an effective technique for measuring the shear wave velocity in the field to assess dynamic soil properties in soft ground.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.36 no.2
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• pp.37-49
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• 2024

To date, numerous empirical formulas have been proposed through hydraulic model experiments to predict the wave breaker index, including wave height and depth of wave breaking, due to the inherent complexity of generation mechanisms. Unfortunately, research on the characteristics of wave breaking and the prediction of the wave breaker index for gravel beaches has been limited. This study aims to forecast the wave breaker index for gravel beaches using representative linear-based machine learning techniques known for their high predictive performance in regression or classification problems across various research fields. Initially, the applicability of existing empirical formulas for wave breaker indices to gravel seabeds was assessed. Various linear-based machine learning algorithms were then employed to build prediction models, aiming to overcome the limitations of existing empirical formulas in predicting wave breaker indices for gravel seabeds. Among the developed machine learning models, a new calculation formula for easily computable wave breaker indices based on the model was proposed, demonstrating high predictive performance for wave height and depth of wave breaking on gravel beaches. The study validated the predictive capabilities of the proposed wave breaker indices through hydraulic model experiments and compared them with existing empirical formulas. Despite its simplicity as a polynomial, the newly proposed empirical formula for wave breaking indices in this study exhibited exceptional predictive performance for gravel beaches.