• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.856-866
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• 2021

The increasing international awareness regarding air pollutant reduction has resulted in increasing demand for eco-friendly ships; hence, electric ships are being actively developed by various countries. Presently, studies on electric ships are mainly focused on electric propulsion systems and electric motors. However, from the ship perspective, there are no studies on conceptual designs for coastal car ferries powered by removable power supply systems. In the present study, the main research consideration is regarding the conceptual design of a fully electrified car ferry using a battery-based removable system as the main power source. By analyzing the dimensions of more than 100 domestic coastal car ferries, the main criteria satisfying the requirements for developing a suitable vessel were derived, and a study on intact/damage stability was conducted considering the application of a removable battery truck. Further analyses of the problems concerning the conceptual design were also performed to derive solutions.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.277-280
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• 2006

This paper deals with the possibility on the hybrid power system concerning wind energy at a really existing island, Sunyoo-do in the west sea near Seamangeum. In the present stage, Diesel system produces all the electrical power of the Island. However, in the new proposed system of Diesel and wind energy, an optimized guideline for drive from the economic analysis on this hybrid system is given by a mathematical and statistical modelling with a share software HOMER (hybrid optimization model for electric renewables). After a series of analysis it has been shown that the hybrid system can reduce the total expenses as well as air pollution.

• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.585-594
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• 2004

When several service providers want to work together with only one master key, they need to properly distribute the key to participants who come in for the co-work business and then securely manage the distributed keys. This paper describes the system that can efficiently and securely manage the master key on the basis of the secret sharing scheme that can reconstruct original secret information as the necessity of reconstructing original secret arises. The proposed system can distribute secret information to several groups and also redistribute the secret to subgroup in proportion to the participant's security level using smart card-based (t, t)-(k, n)-threshold secret scheme for securely keeping secret information and authentication of participant's identification.

• Journal of Korea Ship Safrty Technology Authority
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• s.32
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• pp.12-29
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• 2012

본 연구는 태양광 발전시스템을 선박에 설치하고, 동 시스템과 연계한 선박 발전시스템에 대한 해상 실증 실험을 통하여 발전 시스템의 작동, 신뢰성과 선박 복원성능 및 경제성을 평가하고, 육상으로 송전하는 계통연계형 시스템에 대한 실험을 동시에 수행하였다. 독립형 발전시스템 선내 부하에 안정적인 전원 공급이 가능하고, 태양광 발전과 선내 발전시스템간의 하이브리드 운전이 안전하여 상용화에 문제가 없으며, 계통연계형 태양광 발전 수익모델 가능성을 확인하였다. 본 시스템 설치선박은 단기간 투자비용 회수가 가능하고, 경제성이 있을 것으로 판단된다. 또한, 태양광 관련 설비에 대한 안전을 확보하기 위하여 안전기준(안)을 제시하였으며, 앞으로 다양한 용량의 발전시스템 선박에 적용이 가능할 것이다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.105-106
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• 2011

전력계통에서 비선형부하와 시변부하 사용의 증가 및 분산전원의 보급 증가로 전력품질(power quality)에 대한 관심이 증대되고 있다. 전력계통에서 전력품질은 전력신호를 통해 모니터링이 가능하다. 하지만 전력신호 상시 관측을 통한 전력품 모니터링은 많은 신호 데이터양이 필요하여 전력 신호 압축이 요구된다. 이에 따라 본 연구에서는 신호 압축 성능이 우수한 DCT(discrete cosine transform)기법을 이용하여 전력신호를 압축, 복원하는 방법을 제안한다. 그리고 DSP (digital signal processor) 보드를 통해서 압축 저장 된 신호를 오차 범위 5% 이내로 복원한다. 따라서 정전과 같은 이벤트(event)가 발생하였을 때 특정시간, 장소에서의 전압과 전류 파형을 볼 수 있게 한다. IEC 61000-4-30, IEEE std 1159에 근거하여 Matlab 프로그램 상에서의 성능을 평가하고 DSP보드를 이용하여 DCT를 이용한 데이터압축 시스템을 구현하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12C
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• pp.249-254
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• 2001

A receiver ASIC for fiber optic modules of STM-1 optical communication has been fabricated with 0.65 $\mu\textrm{m}$ CMOS technology. The ASIC has a limit amplifier circuit for the 155.52 Mbps data reshaping, and a clock extraction circuit for the 155.52 MHz clock recovery. The ASIC has an acquisition aid and LOS monitoring circuit for properly operation with near 155.52 MHz clock frequency in case of the data loss due to transmission line open or data transfer fail. Measured results show that the circuit reshapes data from 5 mV to 1 V wide range of input voltage condition, add it recovers system clock with stable on any condition.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.2
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• pp.148-154
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• 2016

In recent year, the interests of PQ is increase due to the increasing of non-linear load and distributed power sources in power system. For the parameters detection and feature extraction of PQ, and the PQ improvement method, continuous power signal monitering is needed. In this paper, the power signal compression and reconstruction method is suggested for power signal monitering. The power signal is compressed using DCT that has good compression performance, and the compressed signal is reconstructed through IDCT. And for the higher compression rate, DCT coefficients are arranged by magnitude in compression process, and in recouction process DCT coefficients are rearranged to original frequency position. The synthesized signal according to the IEC standard is used used in compression and reconstruction simulations. The performances of the proposed method are verified by comparing the error between synthesized signal and reconstructed signal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1074-1079
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• 1999

A high performance CMOS receiver for 155.52 Mbps STM-1 digital communication has been designed and fabricated. The ASIC operates properly with 155.52 MHz clock frequency in case of the data loss due to some system error such as transmission line open or data transfer fail. Also it operates properly in case the system starts after the power failure or system maintenance. The designed circuit has especially PLL based self oscillation loop which operates on abnormal environment which is added to main oscillation loop. The measured results show that the circuit operates well with 153.52 MHz clock frequency not only on normal environment but also on abnormal environment. Rms jitter of the PLL loop is about 23 ps.

• The Journal of Society for e-Business Studies
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• v.8 no.3
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• pp.165-176
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• 2003

Instead of existing cell phones, PDAs are observed as leading wireless Internet devices recently Numerous applications are developed by extended usage of PDAs and it should be installed appropriately according to devices. Furthermore, when battery is discharged, all data stored in RAM(Random Access Memory) becomes obsolete. So it should be recovered or reinstalled from flash memory, backup media or something. In this paper, we present an automatic application installation system(PAIS : PDA Automatic Installation System) to solve problems that users have to install applications by themselves whenever it is necessary. With this system, users feel comfortable by saving time and effort to install each applications and application development companies save cost needed to make materials illustrating installation process. Consequently PAIS may flourish wireless Internet business.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.685-690
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• 2003

The application for PDA as a new wireless Internet device is variously developed to improve the function of PDA, and the application software must be installed to PDAs. In addition. when the power supply of PDA becomes fully discharged, all data stored in the RAM (Random Access Memory) could be vanished, and then the application programs should be reinstalled. This paper presents an automatic installation system of application program, PAIS (PDA Automatic Installation System). It is designed to solve the problem of PDA that PDA's users have to install the application programs on their PDA themselves. When this engine is applied, PDA users can save the time and effort for installation. It's convenient for the PDA users. The PDA and application software company can save the cost to create materials to explain the installation process.