• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.6
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• pp.1255-1261
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• 2014

Based on the radio wave measurement of korean ocean-based DGPS by season, in this paper, the service coverages of ocean-based DGPS reference stations were analyzed according to the climate and season. The signal strengths and signal-to-noise ratios in the land service areas that are provided by ocean-based DGPS reference stations were measured. The ocean-based DGPS reference station except reference stations on the mountainous terrain and the low ground conductivity provide more than 68% service area in comparison with the designed land service coverage providing by the ocean-based DGPS reference stations. To provide the designed service area that is unrelated to a season, it is necessary to install and operate the DGPS reference station with good ground conductivity and high efficiency antenna. Also, the poor service regions which is generated by obstacles of electric wave on pathway can be resolved by the double service area providing by land-based DGPS reference stations.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.437-443
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• 2014

Based on the radio wave propagation measurement of DGPS land-based reference stations, the DGPS service coverage and signal quality in the receiving points are analyzed in this paper. The DGPS signal strength and SNR in the receiving point are measured in the winter and summer season, respectively. In case of DGPS reference station that can not provide the designed service coverage, the solution to improve the service coverage is presented in this paper. Almost all DGPS reference station except reference station with low ground conductivity or mountainous terrain provide the DGPS service coverages of 80% or more of the designed service area. The service coverages of DGPS reference stations can be improved to pre-designed service area in case of installation management of DGPS site on the plain terrain and good ground conductivity. It is necessary to get the high efficiency of transmitting antenna to improve the service area.

• Journal of the Korean Geographical Society
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• v.38 no.6
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• pp.887-905
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• 2003

In this paper, we first understand the concept of imperialism as a 'a dialectical relation between territorial and capitalistic logics of power', as suggested by Harvey, and its history with three phases, the last of which would be seen as the phase of new imperialism. Secondly, we examine the New Security Strategy of the U.S which can be seen as a reflection of the new imperialism of the U.S. with its neo-conservative Bush administration, and explain the wars in Afghanistan and Iraq as the implementation of the new imperialism. And then we take a close look on the current geopolitical situation of East Asia, especially North and South Korea, Japan and China, in terms of the new imperialist foreign policy of the Bush administration. Finally, we consider the limits of the new imperialism of the U.S. and globally emerging movements of anti-imperialism.

• Journal of Practical Engineering Education
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• v.11 no.1
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• pp.117-123
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• 2019

The aim of this study was to investigate the priority partner countries for technical vocational education and training (TVET), using the cluster analysis. The partner countries were prioritized for finance supports and knowledge sharing. We had also redesigned the TVET assistance process as well as reflected the needs of recipient countries for TVET. Especially, by redesigning the methodological support process, we also increased the effectiveness and efficiency of TVET official development assistance. In research method, potential 24 priority partner countries have been designated by the international development cooperation committee and selection criteria of international cooperation agencies and banks. Then, we conducted the cluster analysis, using three main variables: economic factor, labor market factor, education factor. In results, we clustered four and three types of the priority partner countries for TVET. In future, we suggested the new approach for selecting the priority partner countries in terms of employment and labor as well as non-designated partner countries, which will need to cooperate for TVET.

• Journal of Digital Convergence
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• v.17 no.10
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• pp.223-232
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• 2019

With the development of the information communication industry, the size of the communication device has been reduced to a system that generates a large amount of heat. Therefore, since the amount of heat generated by the wireless equipment is large in the wireless base station, the energy consumption is continuously consumed and the failure of the wireless base station may occur. Therefore, in this study, The study was analyzed. As a research method, we performed base station with a lot of calorific value and electric charge. We selected 25 base stations and obtained data for two weeks. To ensure reliability, the room temperature was kept constant at $27^{\circ}C$, and the control system was installed and equiped for two weeks to obtain the date analysis. In order to calculate the test results in the study method, the instrument was used with a computer, a digital thermometer, and dust measurement. For the date analysis, we conducted a research study on 25 wireless basestations before and after the installation of Control Sysetm.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.81-89
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• 2022

This study measured the radio environment of 10 domestic institutions with CubeSat ground stations for 24 hours in three frequency bands (VHF/UHF/S-band) allocated by the International Telecommunication Union (ITU). The impact of the RF environment around the ground stations on CubeSat downlink frequencies was analysed and compared with acceptable interference noise requirements from the CubeSat RF link. The findings indicate that not only the selection of downlink frequency but also the configuration of RF communication link design and ground station system of CubeSat should consider the S-band RF environment around the ground station due to the presence of several wireless devices.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.745-758
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• 2022

As the unlimited natural source of a country, radio waves are widely being used in the daily life toward knowledge based information society. Therefore it is necessary to provide a long term policy of radio waves management policies based on market situation to cope with rapidly changing wireless technology and effective use of radio resources. Literary survey and analysis were accomplished for the rules and regulations in the radio station approval system and post-approval policies for mobile communication service. In conclusion, this study propose an blanket radio approval policy as well as self declaration of conformity(SDoC) of radio waves technical regulation and advanced radio inspection procedure. This study has significance in providing reference for introducing deregulation policy in the radio communication imdustry.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.229-236
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• 2022

This article studied the radio station inspection method, which utilizes the 8T8R combiner to reduce 5G radio station inspection measurement times. It is a common that 5G radio station inspections measure RF (Radio Frequency) output signals, which correspond to the number of arrayed antennas individually. However, this study suggested a way to save the time spent on existing methods, by comparing measurement values of individual channels and 8T8R. As a result, it is confirmed that when the 8T8R combiner is used, not only the resulting value of radio station inspections was accurate, but also the measurement time being shortened by up to 8 times compared to existing method.

• Korea Trade Review
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• v.48 no.1
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• pp.165-191
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• 2023

The US and EU have imposed energy sanctions on the Russian oil and gas sector in response to the Ukraine crisis. One of the key measures is to cut oil and gas imports from Russia. The US and EU are both the senders of sanctions against Russia. However, there is a fundamental difference between them. While the US is the net oil and gas exporter, most EU member states are heavily dependent on Russian oil and gas. If the US and other major oil and gas exporting countries can replace Russia in the EU energy market, the effectiveness of energy sanctions against Russia can be guaranteed. Our result shows that it is difficult for the major oil and gas exporters to fully replace Russia in the short run because of the lack of additional production capacity and infrastructure. We conclude that the US and EU's energy sanctions against Russia can not guarantee its effectiveness. We argue that other measures, such as diplomacy, should be taken to settle the conflicts in Ukraine.

• Journal of Korean Electronics
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• v.12 no.7
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• pp.101-102
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• 1992