• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.2
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• pp.143-150
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• 1993

Shallow sub-bottom reflection recorders are obtained using dual frequency (15/100 KHz). The main goal of this study is to enhance the resolving power and penetration for the sub-bottom reflection of the sub-marine seismic exploration. The Fresnel zones of spherical waves for the near-field are of great importance to reach the high resoluton. In case a target to detects than the Fresnel radius, a diffraction hyperbola on the recorder is observed. A larger attenuation of sand makes less penetration than the smaller attenuation of silt and clay. It is found that the selective frequency as well as the seismic energy generation is the most important factors for sub-marine exploration. This technique of using dual frequency sub-marine exploration may be applied to detect the sub-bottom sludge soil, ocean contamination and marine archaeological relics.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.12a
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• pp.87-100
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• 2007

Marine controlled source electromagnetics (CSEM) or sea bed logging (SBL) is an emerging technology which can provide quantitative information on hydrocarbon reservoir embedded in marine sediment. Electromagnetic responses to the resistive formation saturated with a certain amount of hydrocarbon can be characterized by less attenuated profile otherwise exponentially attenuated fields in conductive sea water or through sediments, and thus can be regarded as a direct indicator of hydrocarbon. In this paper, we introduce the technology of marine CSEM in terms of its physical characteristics and in comparison of typical three-dimensional (3-D) seismic method. History and evolution of commercial marine CSEM are also briefly summarized. We then introduce a representative case history showing how marine CSEM works in reality. Outlook of future applications and technical advances to be made are discussed. Finally, we demonstrate a test example of 2.5-D inversion of synthetic data as the groundwork of 3-D inversion of field data that is to be the ultimate goal of technical development.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.12a
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• pp.53-62
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• 2007

Preliminary gas hydrate surveys were carried out From 2000 to 2004 in the East Sea. Research results showed the geophysical evidence of gas hydrate existence. In 2005, Gas Hydrate R&D Organization was established and 10 year gas hydrate development program was initiated. In the $1^{st}$ stage of the program from 2005 to 2007, 6,600 L-km 2-D seismic survey was conducted in the $1^{st}$ year 2005, and $400\;km^2$ 3D survey was conducted in the $2^{nd}$ year 2006. Acquired seismic data were processed and seismic section and 3D cube were produced. By geophysical interpretation and velocity analysis, prospective areas were mapped and candidate drilling sites were recommended. For the precise interpretation, velocity was analyzed using AVO method, and BSR signal was analyzed using deconvolution method. For the prospective area, OBS and high-resolution seismic surveys were conducted. This presentation shows the introduction and examples of the research results of the geophysical methods applied for the gas hydrate exploration in the East Sea.

• Spatial Information Research
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• v.18 no.4
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• pp.65-73
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• 2010

Recently, the importance of the ocean has been increasing internationally as the new source for mineral resources following the exhausted land resources that arc becoming scarce. On a long-term aspect, growth of nations by gaining competitiveness on marine resources was considered a paradigm. Because dominating the development right of marine resources came up as the main concern. South Korea has also been interested in marine resources and this is the reason why massive amounts of marine exploration data arc annually created through surveying and drilling around the Korean Peninsula. but the data has not been systematically managed very well because of its economic costs. Therefore, this research is mainly focused on systematical data managing methods. For Systematical data management. the exploration data is integrated and organized by using XML tables. This can be a systematical data management. because the methods release dependency between data and system, and it also enables to update existing data and renew the data. In the future, the constructed database from this study could definitely contribute to enhancing data management. As well, the developed system in this research can provide various spatial analysis and searching techniques to enable easier data provision of various exploration areas. Furthermore. this will be very useful to extend functions of the system and to adopt other types of DBMS. In addition, the spatial analysis and search function of location based service can be utilized through GIS. and it can support sustainable and systematic management in a long term.

• Economic and Environmental Geology
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• v.47 no.6
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• pp.673-681
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• 2014

Recently, many countries in the world try to develop alternative energy sources, however, traditional hydrocarbon resources are still occupying most of the energy resources. Exploration demands for high technologies are increasing in the development of limited oil & gas resources field owing to the exhaustion of hydrocarbon resources for access area. Therefore, an effort for the development and the application of new technologies such as azimuth seismic survey, ocean-bottom seismic survey and marine controlled-source electromagnetic survey is necessary as well as an understanding of the existing technologies such as 2D/3D seismic survey. This dissertation is designed with the purpose of introducing marine hydrocarbon exploration technologies and analyzing their internalexternal researches, development and science information. In this study, we analised total 616 dissertations for the marine petroleum exploration released in the Sci-expanded DB of 'web of science' during the 2001~2014 periods.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.211-211
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• 2012

• Journal of Power Electronics
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• v.18 no.2
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• pp.395-406
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• 2018

Marine controlled-source electromagnetic transmitters (MCSETs) are important in marine electromagnetic exploration systems. They play a crucial role in the exploration of solid mineral resources, marine oil, and gas and in marine engineering evaluation. A DC-DC controlled-source circuit is typically used in traditional MCSETs, but using this circuit in MCSETs causes several problems, such as large voltage ringing of the high-frequency diode, heating of the insulated-gate bipolar transistor (IGBT) module, high temperature of the high-frequency transformer, loss of the duty cycle, and low transmission efficiency of the controlled-source circuit. This paper presents a clamping-diode circuit for MCSET (CDC-MCSET). Clamping diodes are added to the controlled-source circuit to reduce the loss of the duty ratio and the voltage peak of the high-frequency diode. The temperature of the high-frequency diode, IGBT module, and transformer is decreased, and the service life of these devices is prolonged. The power transmission efficiency of the controlled-source circuit is also improved. Saber simulation and a 20 KW MCSET are used to verify the correctness and effectiveness of the proposed CDC-MCSET.

• Journal of Fisheries and Marine Sciences Education
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• v.20 no.2
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• pp.297-308
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• 2008

This study developed career education program applying cooperative learning structures (Kagan, 1993, 1995, 1997), and tested its effect on elementary school children's career development. Sixth grade students of 2 classes were divided into experimental and control group, and 14 sessions of the program were applied to the experimental group for 8 weeks. Career development test(Lee, 2005) were performed before and after the program. Students in both groups were retested 3 months after the post-test to test continuing effects of the program. Score tendencies and their differences between experimental group and control group of children in 3 career development areas - self-awareness, educational and occupational exploration, and career planing - were tested and the results are as follows: development of 3 areas of self-awareness, educational and occupational exploration, and career planing were consistently increasing along the experimental sequence in experimental group, while the development of 3 areas showed no changes or declining tendencies in control group. Self-awareness and educational and occupational exploration did not show the statistically significant differences between the groups. Meanwhile, the career plaining showed statistically significant difference between the groups in post-test, meaning that the career education program with cooperative structure has positive effects on the career planing in 6th grade students.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1125-1126
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• 2008

Currently for exploring marine resources, After confirming the location of the resources by controlling search equipment and sensor module, the method which collects sample of searched resources and analyzes the quality and a contents of the resources in research vessel is been applying. This search method is structure which analyzes an ingredient in ship and decides the quality of the resources. And real-time processing for an effective resources search is been demanding. Therefore we have developed a exploration system of marine resource that can display the type feature of resources by Graphic User Interface.

• Journal of Ocean Engineering and Technology
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• v.32 no.4
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• pp.287-295
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• 2018

This paper presents the results of an exploration of the ferromanganese crusts of Western Pacific Seamount registered by the Korean government. This area has been surveyed with a deep-sea camera and crust samples have been acquired by deep-sea dredging since 2013. On October 18-19, 2017, a united research team from KIOST and KRISO explored two blocks, OSM11 and OSM07, on the seamount using Hemire ROV. A precise survey was conducted on the ferromanganese crusts and sediments covering the slope/top of OSM11 and the middle flat area of OSM07. Rock samples were collected with precise positioning, and HD videos were recorded for 7 hours. This paper discusses the technical issues of this exploration in terms of (1) how to deal with an emergency situation during an electric power blackout, (2) the improvement of the thruster power by adding cooling plugs to the housings of the thruster amplifiers, (3) the relative motion of the depressor by changing the fixing method of the cable terminator, which affects the service life of the cable, (4) a sampling technique for the steep slope of the seamount, (5) integrated navigation under a USBL blackout, and (6) a 3-dimensional image mosaic for visualizing the distribution state of the crusts.