• Ocean and Polar Research
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• v.42 no.2
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• pp.171-178
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• 2020

R/V EARDO, commissioned in 1992, has successfully carried out ocean research campaigns in Korean jurisdictional and adjacent waters, including continental margins and coastal zones within the Korean Exclusive Economic Zone (EEZ), for 29 years. However, it will soon be reaching the end of its useful service life. A replacement for R/V EARDO is urgently needed to ensure the safety of vessel itself and its crews, and efficient ship operation and maintenance, as well as to meet modern scientific mission requirements (SMRs). Basic specifications for a replacement ship have been devised and reviewed over the past nine months. A test of the proposed hull form was also performed. The total tonnage of the proposed vessel is approximately 740 tons, and the overall length and width are 62.0 and 11.6 m, respectively. The new ship will thus be 73% larger than the current R/V EARDO; in particular, the research workspace will be 4.4 times larger. The major design priorities are the propulsion system, efficiency of radiated noise and vibration control, and the dynamic positioning system. An environmentally friendly emission system, meeting International Maritime Organization (IMO) Tier III regulations, will be installed in the third exhaust pipe. Various wet and dry lab spaces as well as 32 different scientific instruments have also been considered in the ship design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3594-3599
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• 2009

The train control system used in Gyeongbu-line is classified in ATC, IXL and CTC. The ATC data related to speed and space control for trains are transmitted from wayside to onboard by way of UM71 AF track circuits and BSP Loop. The information transferred by track circuits is composed of operation data which directly influence to the train operation and the information transferred by BSP Loop is used in the section which requires the additional data transmission about the particular track-side environment such as tunnel, hot box detector or insulated section. In this paper, for the BA type turning unit of the UM71 AF track circuits which is mainly used in the linking section of existing and high-speed lines from the opening of the Gyeongbu line till the present, we not only analyze the characteristics of BA but also compare and analyze baseline values and the measured values. With this analysis, we will be able to propose how to solve the problems about operation and maintenance such as track circuit malfunctions of the relevant sections.

• Journal of IKEEE
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• v.22 no.3
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• pp.630-637
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• 2018

To supply a high voltage to an inverter, a motor control unit (MCU) generally employs a front-end boost converter. Because it generates a high output voltage, the converter needs an output capacitor, which has a high working voltage resulted in cost increasing. To solve this problem, we present a bidirectional dc-to-dc converter, which can decrease a working voltage of the output capacitor. Basic characteristic of the proposed converter is similar to a conventional boost converter. A difference comes from the structure of the output terminal connecting an output capacitor and an input battery in series. Owing to this circuit configuration, the working voltage of the output capacitor becomes lower than that of a conventional boost converter. After theoretical analysis, we carry out simulations and experiments to verify the validity and performance comparing with a conventional boost converter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2503-2510
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• 2015

This paper presents a single-phase energy measurement IC to measure electric power quantities. The entire IC includes two programmable gain amplifiers (PGAs), two ${\sum}{\Delta}$ modulators, a reference circuit, a low-dropout (LDO) regulator, a temperature sensor, a filter unit, a computation engine, a calibration control unit, registers, and an external interface block. The proposed energy measurement IC is fabricated with $0.18-{\mu}m$ CMOS technology and housed in a 32-pin quad-flat no-leads (QFN) package. It operates at a clock speed of 4,096 kHz and consumes 10 mW in 3.3 V supply.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.349-352
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• 2003

A personal low-frequency stimulator is a portable device to relax muscle pains of a person. The stimulator generates combined low-frequency pulses to be applied to pads attached to painful muscles. This paper reports a development of such device with its characteristic analyses. The major components of our stimulator are MCU, high-voltage generating circuit part, high-voltage switching circuit part, input switch part and display unit. High-voltage generating circuit is designed by using a boost converter circuit and allows user control of the output voltage. High-voltage switching circuit, controlled by MCU, generates output voltage to be applied to pads. Input switch part is composed of power supply, intensity selection, mode selection and memory. Display unit adopts a text LCD module to display modes, Intensity, output frequency and user set-up time. Our designed safety circuit, to protect human body from possible electric shock, slowly increases the output voltage to the selected output intensity. It continuously checks the output pulse shape and disable the output when dangerous pulses are detected. This paper also shows some experimental results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.3
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• pp.273-288
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• 2010

In this paper, we propose a cooperative multi-relay scheme for a secondary system to achieve spectrum access along with a primary system. In the primary network, a primary transmitter (PT) transmits the primary signal to a primary receiver (PR). In the secondary network, N secondary transmitter-receiver pairs (ST-SR) selected by a centralized control unit (CCU) are ready to assist the primary network. In particular, in the first time slot, PT broadcasts the primary signal to PR, which is also received by STs and SRs. At STs, the primary signal is regenerated and linearly combined with the secondary signal by assigning fractions of the available power to the primary and secondary signals respectively. The combined signal is then broadcasted by STs in a predetermined order. In order to achieve diversity gain, STs, SRs and PT will combine received replicas of the primary signal, using selection combining technique (SC). We derive the exact outage probability for the primary network as well as the secondary network. The simulation results are presented to verify the theoretical analyses.

• IE interfaces
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• v.25 no.4
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• pp.393-404
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• 2012

Increasing safety requirements of automobile are asking companies to find out solutions, based on the ISO 26262 which is a functional safety standard. ISO 26262 is an adaptation of the IEC 61508 for automotive electric/electronic systems. ISO 26262 provides a V model for ECU (Electronic Control Unit) development process to secure safety against vehicle. It well describes the requirements, necessary works and their resulting products for each development phase. However, it is difficult to apply to product development for achieving functional safety in the electric/electronic systems of an automobile because it lacks explanation on the working steps to follow and the methodologies and tools to be used in each step. In this paper, we introduce the outline of the ISO 26262 product development process and present a DFSS (Design For Six Sigma) road-map based on the ISO 26262 product development process as a way to operate efficiently the ISO 26262 product development process. The DFSS road-map consists of five phases: Define, Measure, Analyze, Design, and Verify. The detailed activities, tools, inputs, and work products are given for each phase.

• Ocean Systems Engineering
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• v.8 no.2
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• pp.101-118
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• 2018

In case of conventional shallow-draft semisubmersibles, unacceptably large riser stroke was the restricting factor for dry-tree-riser-semisubmersible development. Many attempts to address this issue have focused on using larger draft and size with extra heave-damping plates, which results in a huge cost increase. The objective of this paper is to investigate an alternative solution by improving riser systems through the implementation of a magneto-rheological damper (MR Damper) so that it can be used with moderate-size/draft semisubmersibles. In this regard, MR-damper riser systems and connections are numerically modeled so that they can couple with hull-mooring time-domain simulations. The simulation results show that the moderate-size semisubmersible with MR damper system can be used with conventional dry-tree pneumatic tensioners by effectively reducing stroke-distance even in the most severe (1000-yr) storm environments. Furthermore, the damping level of the MR damper can be controlled to best fit target cases by changing input electric currents. The reduction in stroke allows smaller topside deck spacing, which in turn leads to smaller deck and hull. As the penalty of reducing riser stroke by MR damper, the force on the MR-damper can significantly be increased, which requires applying optimal electric currents.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.153-160
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• 2015

Hybrid Electric Vehicles(HEVs) have seriously come into prevalence recently as car manufacturers and consumers have become more aware of the environmental and economic problems of conventional vehicles. For the alternative power-train and battery cooling systems in HEVs, an effective thermal management system is required, and many automakers are interested in using Brushless DC(BLDC) motors for cooling fans for the overall traction unit's performance and energy saving capability. This paper presents the development status of BLDC motors as major parts of the power-train, i.e. the engine cooling and battery cooling fans of HEVs. A design that uses BLDC motors for the power-train and each battery cooling fan, is successfully implemented through using electro-magnetic analysis, and prototype BLDC motors are examined. As experimental results, the BLDC motors achieved an efficiency of 85% as engine cooling fans and 72% as a battery thermal management fan motor. The electric cogging noise is significantly reduced by changing the skew of the slot pitch angle and optimizing the magnetic shape.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.1
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• pp.18-22
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• 2015

When using a secondary battery in energy storage units, if the grid is in light duty the active power is stored so it can be used when the grid is in heavy duty. This makes possible for the load equalize and make the grid optimized. Recently the government is trying to propagate this technology. Depending on its capacity this kind of electric energy storage unit is used in adjusting the frequency, break up the energy peak in summer and winter, stabilize the energy output of renewable energy which can change unstably because of the environment. Which makes it possible to stabilize the grid. It is anticipated that market of 120 trillion won will be developed worldwide in 2030. Currently in Korea a steady supply is in progress. However because of stray electromagnetic waves some other electronics are malfunctioning. This paper covers the research in the method to detect the emission noise in small electric energy storage units using lithium secondary batteries and battery management system, Power conditioning systems with CIPSR standards. And the research of a more efficient method to measure such stray electromagnetic waves.