• Strategy21
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• s.33
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• pp.178-201
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• 2014

China National People's Congress has passed the bill to combine the Marine Law Enforcement into "State Oceanic Administration People's Republic of China". This bill was intended to resolve the overlapping jurisdiction and disputes caused in ocean territory in nearby countries. The purpose of reorganizing the administration was to combine the dispersed organization into one group. This new big administration was basically organized to increase the power of China marine state on the long-term. The reorganization plan is to group General Administration of Customs, China Marine Surveillance, Fisheries Law Enforcement Command, and Border Control Department into one State Oceanic Administration. The new state Oceanic Administration carries the authority to protect rights and enforce the marine law supported by Public Security Bureau. Korea Coast Guard has been cooperating with China Marine Surveillance since 1998 when the first pact was made. The next step expanded to General Administration of Customs. Currently working with Regional Maritime Law Enforcement organizations dealing mostly with illegal Chinese fishing boats and IEODO conflict. In order to solve the problems we face today is to observe the process of the New China Coast Guard administration, analysing the effects that could be caused by the change and to keep close cooperation between the new administrations.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.514-520
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• 2015

This paper presents a novel shore-to-sea maritime data transmission system based on time-code diversity, using visible light in maritime environments to overcome the limitations of conventional maritime wireless communications. The proposed system is primarily comprised of existing LED-based lighthouses and maritime transceivers (marine beacons, buoys, etc.), and thus is considered cost-effective in terms of implementation. We first analyze maritime visible-light communications on the basis of the unique properties of a maritime environment, i.e. sea states (wave height, wind speed, etc.), plus atmospheric turbulence, using the Pierson-Moskowitz (PM) and JONSWAP (JS) spectrum models. It is found that the JS model outperforms the PM model, and that the coverage distance depends on the LED power and sea states. To combat maritime fading conditions that significantly degrade performance and coverage distance, we propose a time-code diversity (TCD) scheme in which the delayed versions of the original data are retransmitted using orthogonal Walsh codes. This TCD scheme is found to be superior, in that it offers three orders of magnitude in terms of BER performance, compared to a conventional (non-TCD) transmission scheme. The proposed scheme is robust and efficient in overcoming the effect of impairments present in maritime environments with a BER of approximately $10^{-5}$and a data rate of 100 Kbps at a distance of 1 km.

• Maritime Security
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• v.6 no.1
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• pp.57-81
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• 2023

This study aims to review Russia's annexation of Crimea from a maritime security perspective. Based on a comprehensive analysis of Russia's national security perception, this study analyzed Russia's maritime security strategy and the security importance of the Black Sea and the Sea of Azov, and reviewed the annexation of Crimea from a maritime security perspective. The main argument of this study is as follows. Russia's annexation of Crimea was necessary for the successful fulfillment of Russia's maritime security strategy in the Black and Azov Seas. Russia's annexation of Crimea guarantees the activities of the Black Sea Fleet militarily from a maritime security point of view, secures a passage to the Atlantic Ocean to counter NATO's expansion. From a economic security point of view, Russia's annexation of Crimea was based on the strategic considerations to secure influence within the Black Sea economic bloc which guarantees stable production and transportation of natural resources and shipping.

• Journal of Power Electronics
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• v.16 no.2
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• pp.464-472
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• 2016

This study applies the selective harmonic elimination (SHE) technique to design and operate a regulated AC/DC/AC power supply suitable for maritime military applications and underground trains. The input is a single 50/60 Hz AC voltage, and the output is a 400 Hz regulated voltage. The switching angles for a multi-level inverter and transformer turns ratio are determined to operate with special connected transformers with equal power ratings and produce an almost sinusoidal current. As a result of its capability of directly controlling harmonics, the SHE technique is applicable to apparatus with congenital immunity to specific harmonics, such as series-connected transformers, which are specially designed to equally share the total load power. In the present work, a single-phase 50/60 Hz input source is rectified via a semi-controlled bridge rectifier to control DC voltage levels and thereby regulate the output load voltage at a constant level. The DC-rectified voltage then supplies six single-phase quazi-square H-bridge inverters, each of which supplies the primary of a single-phase transformer. The secondaries of the six transformers are connected in series. Through off-line calculation, the switching angles of the six inverters and the turns ratios of the six transformers are designed to ensure equal power distribution for the transformers. The SHE technique is also employed to eliminate the higher-order harmonics of the output voltage. A digital implementation is carried out to determine the switching angles. Theoretical results are demonstrated, and a scaled-down experimental 600 VA prototype is built to verify the validity of the proposed system.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.3
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• pp.161-161
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• 1996

In this paper the recent studies of digital governor for the Diesel Engine in Korea is summarized and that of usage in the marine and land field as of power plant is analyzed for the interest and development of the enterprise with relation with relation to this industrial part. Our investigation shows that until now the studies on the digitl governor are mainly carried out in KMU and land usage for the power plants is increased gradually because reliance of digital governor is improved and system for the maneuvering and monitoring the plants is computerized.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.177-178
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• 2018

본 논문에서는 직렬형 Hot-Swap ESS(Energy Storage System)를 구성하는 전력 변환 시스템에서 전류 센서의 옵셋 오차가 제어 성능에 미치는 영향에 대해 살펴보았다. 양방향 DC-DC 컨버터와 DC-AC 인버터에서 전류 센서 옵셋 오차의 영향에 대해 분석하고, 컴퓨터 모의 시험을 진행하여 그 특성을 파악하였다.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.198-202
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• 2001

This paper presents a novel prototype version of ZCS-PWM forward DC-DC power converter using power MOSFETs which is designed for application specific low voltage large current conversion operation. The soft-switching forward power converter with a high frequency isolated transformer link which can efficiency operate over wide load ranges under two conditions of ZCS as well as active voltage clamped switching is evaluated and discussed on the basis of the simulation and experimental results.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1407-1414
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• 2016

Unlike existing pulse-width modulation (PWM) techniques, such as sinusoidal PWM and random PWM, the wavelet PWM (WPWM) technique based on a Harr wavelet function can achieve a high fundamental component for the output voltage, low total harmonic distortion, and simple digital implementation. However, the original WPWM method lacks output voltage control. Thus, the practical application of the WPWM technique is limited. This study proposes an improved WPWM technique that can regulate output voltage amplitude with the addition of a parameter. The relationship between the additional parameter and the output voltage amplitude is analyzed in detail. Experimental results verify that the improved WPWM exhibits output voltage control in addition to all the merits of the WPWM technique.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1517-1523
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• 2015

The wavelet PWM (WPWM) technique has been applied in two-level inverters successfully, but directly applying the WPWM technique to three-level inverters is impossible. This paper proposes a WPWM technique suitable for a single-phase three-level inverter. The work analyzes the control strategy with the WPWM and obtains the design of its parameters. Compared with the SPWM technique for a single-phase three-level inverter under the same conditions, the WPWM can obtain high magnitudes of the output fundamental frequency component, low total harmonic distortion, and simpler digital implementation. The feasibility experiment is given to verify of the proposed WPWM technique.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1119-1124
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• 2014

This paper describes the emergency situation which occurs in Drilling Rig power system. Especially, we focused on power system transient characteristics on propulsion motor load and generator elimination situation in Drilling Rig operation. We performed numerical simulation and analyzed the result for power system transient stability characteristics on each condition for excitation system and governor control system using ETAP (Electrical Transient Analysis Program).