• Title/Summary/Keyword: 전원 구성

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A Charge Pump Circuit in a Phase Locked Loop for a CMOS X-Ray Detector (CMOS X-Ray 검출기를 위한 위상 고정 루프의 전하 펌프 회로)

  • Hwang, Jun-Sub;Lee, Yong-Man;Cheon, Ji-Min
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.13 no.5
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    • pp.359-369
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    • 2020
  • In this paper, we proposed a charge pump (CP) circuit that has a wide operating range while reducing the current mismatch for the PLL that generates the main clock of the CMOS X-Ray detector. The operating range and current mismatch of the CP circuit are determined by the characteristics of the current source circuit for the CP circuit. The proposed CP circuit is implemented with a wide operating current mirror bias circuit to secure a wide operating range and a cascode structure with a large output resistance to reduce current mismatch. The proposed wide operating range cascode CP circuit was fabricated as a chip using a 350nm CMOS process, and current matching characteristics were measured using a source measurement unit. At this time, the power supply voltage was 3.3 V and the CP circuit current ICP = 100 ㎂. The operating range of the proposed CP circuit is △VO_Swing=2.7V, and the maximum current mismatch is 5.15 % and the maximum current deviation is 2.64 %. The proposed CP circuit has low current mismatch characteristics and can cope with a wide frequency range, so it can be applied to systems requiring various clock speed.

Implementation of User-friendly Intelligent Space for Ubiquitous Computing (유비쿼터스 컴퓨팅을 위한 사용자 친화적 지능형 공간 구현)

  • Choi, Jong-Moo;Baek, Chang-Woo;Koo, Ja-Kyoung;Choi, Yong-Suk;Cho, Seong-Je
    • The KIPS Transactions:PartD
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    • v.11D no.2
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    • pp.443-452
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    • 2004
  • The paper presents an intelligent space management system for ubiquitous computing. The system is basically a home/office automation system that could control light, electronic key, and home appliances such as TV and audio. On top of these basic capabilities, there are four elegant features in the system. First, we can access the system using either a cellular Phone or using a browser on the PC connected to the Internet, so that we control the system at any time and any place. Second, to provide more human-oriented interface, we integrate voice recognition functionalities into the system. Third, the system supports not only reactive services but also proactive services, based on the regularities of user behavior. Finally, by exploiting embedded technologies, the system could be run on the hardware that has less-processing power and storage. We have implemented the system on the embedded board consisting of StrongARM CPU with 205MHz, 32MB SDRAM, 16MB NOR-type flash memory, and Relay box. Under these hardware platforms, software components such as embedded Linux, HTK voice recognition tools, GoAhead Web Server, and GPIO driver are cooperated to support user-friendly intelligent space.

Triboelectrostatic Separation of Unburned Carbon from Flyash for Ash Recycling (마찰대전 정전분리기를 이용하여 석탄회에 함유된 미연탄소분 제거에 관한 연구)

  • 이재근;김성찬;손낙원;김두현;오정근
    • Resources Recycling
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    • v.6 no.3
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    • pp.15-21
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    • 1997
  • Flyash from a coal-hed power plan1 is produced approximtcly 3 million tons m 1996 and causes the serious environmentalpmblem due to the disposal in the ash pond. Flyash is an accepted additive in concrete where it adds strength, sulfate ateresistanceand reduced cost, provided acccptablc levcls of unbunrned carbon are mmtmed This papzr describes to investigate thc technicalfeasibility of a dry triboelcctrostatlcp roccss to scparate unburned carbon h m f lyash into economically valuable produck Puliclesof unburned carbon and flyash can be impded positivc and negative surface charzes. rcapeclively. with a copper tniochargcr dueto dirferences in the work function values of thc particles and the tnbacharger. and cm he separated by passing thcm throuph anexternal electic field. A laboratory s d e separation system consists of r sacw feeder for ash supply, a tniocharger, verticalcollecling copper plates, power supplies, a flow meter, and a fan. Separation tests taking into account separahian efficiency and ashrecovery showed that flyash recovery was sh-nngly dependent an thc tnbocharger geomzhy, elect"c ficld strength. flyssh s ~ c a,n dash feeding late. Optimal separation conditions were flyash size less than 125 Fm and electric field shcngrh of 200 kV1m. Ovcr 80%of the flyash with 7% lass on ignition was recovered at wrbon contznts less than 3%bon contznts less than 3%

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A Study on Detection Algorithm of Open Phase Fault in Grid-Connected Transformer for PV System (태양광전원 연계용변압기의 결상사고 검출 알고리즘에 관한 연구)

  • Kang, Kab-Seok;Tae, Dong-Hyun;Lee, Hu-Dong;Rho, Dae-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.5
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    • pp.22-33
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    • 2021
  • In the case of open phase faults caused by the disconnection of distribution feeders interconnected to a PV system, many problems can occur depending on the core type and wiring method of the grid-connected transformers. Moreover, open phase faults are difficult to detect because the open phase voltage of the existing protection relay (Open Phase Relay (47)) can be maintained, even though a disconnection fault occurred, depending on the wiring method and the iron core type of the grid-connected transformer for a PV system. Therefore, this paper proposes a novel algorithm to detect open phase faults by comparing the currents and phases between the primary and secondary sides of a grid-connected transformer. In addition, this paper presents the modeling of a distribution system and protection devices for detecting open phase faults using PSCAD/EMTDC S/W, and implements a test protection device for detecting open phase faults based on the above-mentioned modeling. The simulation and test results confirmed that the proposed algorithm is useful for detecting open phase faults according to the wiring method and iron core type of grid-connected transformer for a PV system because operation slope and unbalance rate of the primary current exceed the setting value (30[%]) of the protection device.

Analysis of Electric Vehicle's Environmental Benefits from the Perspective of Energy Transition in Korea (에너지 전환정책에 따른 전기자동차의 환경편익 추정연구)

  • Jeon, Hocheol
    • Environmental and Resource Economics Review
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    • v.28 no.2
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    • pp.307-326
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    • 2019
  • The electric vehicle is a representative measure to reduce greenhouse gas and local air pollutants in the transportation sector. Most countries provide purchase subsidies and tax reductions to promote electric vehicle sales. The electric vehicles have been considered as zero-emission vehicles(ZEV) in light of the fact that there has been no pollutant emission during driving. However, recent studies have pointed out that the pollutant emitted from the process of generating electricity used for charging the electric vehicles need to be treated as emissions of the electric vehicles. Furthermore, the environmental benefits of electric vehicle replacing the internal combustion vehicle vary with the power mix. In line with the recent studies, this study analyzes the impact of electric vehicles based on the current power mix and future energy transition scenarios in Korea. To estimate the precise air pollutants emission profile, this study uses hourly electricity generation and TMS emission data for each power plant from 2015 to 2016. The estimation results show that the electric vehicles under the current power mix generate the environmental benefits of only -0.41~10.83 won/km. Also, we find that the environmental benefit of electric vehicle will significantly increase only when the ratio of the coal-fired power plant is reduced to a considerable extent.

A Review of Structural Batteries with Carbon Fibers (탄소섬유를 활용한 구조용 배터리 연구 동향)

  • Kwon, Dong-Jun;Nam, Sang Yong
    • Applied Chemistry for Engineering
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    • v.32 no.4
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    • pp.361-370
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    • 2021
  • Carbon fiber reinforced polymer (CFRP) is one of the composite materials, which has a unique property that is lightweight but strong. The CFRPs are widely used in various industries where their unique characteristics are required. In particular, electric and unmanned aerial vehicles critically need lightweight parts and bodies with sufficient mechanical strengths. Vehicles using the battery as a power source should simultaneously meet two requirements that the battery has to be safely protected. The vehicle should be light of increasing the mileage. The CFRP has considered as the one that satisfies the requirements and is widely used as battery housing and other vehicle parts. On the other hand, in the battery area, carbon fibers are intensively tested as battery components such as electrodes and/or current collectors. Furthermore, using carbon fibers as both structure reinforcements and battery components to build a structural battery is intensively investigated in Sweden and the USA. This mini-review encompasses recent research trends that cover the classification of structural batteries in terms of functionality of carbon fibers and issues and efforts in the battery and discusses the prospect of structural batteries.

A study on difference of supervision perception between supervisors and supervisees (수퍼바이저와 수퍼바이지 간의 수퍼비전(Supervision) 인식 차이)

  • Kim, Do-Muk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.6
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    • pp.357-374
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    • 2021
  • This study examined the difference in perception of supervision between supervisors and supervisees of community welfare centers. The survey subjects were 100 social workers working at social welfare centers in Seoul, Busan, and Incheon. The survey subjects were 62% women and 38% men in their 30s. Approximately 98% of supervisors and 88% of supervisees had a college degree or higher. Regarding the total working period of social welfare institutions, 82% of supervisors and 12% of supervisees had five years or more experience. Regarding the perception of the overall supervision between the supervisors and supervisees, the supervisors and supervisees reported a score of 3.79 and 3.46, respectively. In the perception of supervision according to function, in the case of administrative supervision recognition, the supervisors and supervisees reported a score of 3.78 and 3.43, respectively, and in the educational supervision recognition, the supervisors and supervisees reported a score of 3.65 and 3.29, respectively. Regarding supportive supervision perception, the supervisors and supervisees reported a score of 3.94 and 3.67, respectively. As shown in the above results, the difference in the perception of supervisor and supervisee's supervision by function shows that the supervisor's supervision by all functions is higher than that of the supervisee. As a result, such supervisions are relatively low among supervisees who are provided with supervisions than supervisions that are perceived as being provided by supervisors.

A Study on Protection Coordination Algorithm for Separating Fault Section in LVDC Distribution System (LVDC 배전계통에 있어서 사고구간분리 보호협조 알고리즘에 관한 연구)

  • Kang, Min-Kwan;Lee, Hu-Dong;Tae, Dong-Hyun;Rho, Dae-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.1
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    • pp.768-776
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    • 2021
  • Current protection-coordination methods use the reverse time characteristics of the T-C curve, which is not effective for a LVDC distribution system because the protective operation time of converters and DC circuit breakers is much faster than AC protection devices. Therefore, an algorithm is proposed for fault-section isolation using the fault current slope to minimize the blackout region and coordinate between converters and protection devices in a rapid and accurate manner. The method deals with the slope characteristics of a fault current, which may depend on the fault location in an LVDC distribution system. Thus, an LVDC distribution system can be operated in a stable manner by isolating the fault section selectively before the shutdown of the main converter using slope characteristics, which change in proportion to the line impedance and fault location. A 1.5-kV LVDC distribution system was modeled to verify the effectiveness of the proposed algorithm using PSCAD/EMTDC. The system is composed of a distribution substation, LVDC converter, and distribution lines. The simulation results confirm that the proposed algorithm is a useful tool for minimizing the fault section in an LVDC distribution system.

A Study on the application method of UPS's Battery Safety for battleship Command and Fire Control System (지휘무장통제체계용 UPS 배터리의 안전성 확보방안 연구)

  • Park, Gun-Sang;Kim, Jae-Yun;Kim, Dong-Gyu
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.3
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    • pp.587-596
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    • 2021
  • Naval battleships have systems to perform special purposes, such as the Command and Fire Control System (CFCS). Some of the this equipment should be equipped with an Uninterruptible Power System (UPS ) to ensure operational continuity and the backup of important data, even during unexpected power outages caused by problems with the ship's power generator. Heavy combat losses can occur if the equipment cannot satisfy the function. Therefore, it is important to design a stable UPS. The battery and Battery Management System (BMS) are two of the most important factors for designing a stable UPS. A power outage will be encountered if the battery and BMS are not stable. The customer will be exposed to abnormal situations, loss of important tactical data, and inability to operate some of the CFCS. As a result, an enhanced safety system should be designed. Thus, this study implemented and verified the improved system in terms of three methods, such as comparative analysis of the batteries, improvement about leakage current of the circuit, and tests of the aggressive environmental resistance to improve the UPS for CFCS.

The Structural Relationship among Personality, Negative Emotion, Motivation, Career Maturity on Mathematical Academic Achievement of Elementary School Students (초등학생의 수학 학업성취도에 영향을 주는 성격, 부정적 정서, 동기특성, 진로 성숙도의 구조적 관계 분석)

  • Kim, Jung Hoon;Lee, Moonsoo
    • Education of Primary School Mathematics
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    • v.25 no.4
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    • pp.279-295
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    • 2022
  • This study was conducted to present implications for mathematics education by identifying the structural relationship among personality, negative emotion, motivation, and career maturity that affects elementary school student's mathematical academic achievement. The participants conveniently sampled 179 students, from 4th to 6th graders enrolled in the same elementary school, and data on their psychological variables were collected in the form of secondary data. The hypothetical structural equation model established based on prior studies was verified with a two-stage approach based on the collected data. It was confirmed that construct validity and construct reliability were secured through assessing the measurement model. In addition, as a result of analyzing the path coefficient of the final structural equation model, five paths were found to be significant: 'personality→motivation', 'personality→career maturity', 'negative emotion→motivation', and 'negative motivation→mathematical academic achievement'. In particular, the path of 'negative emotion→negative motivation→mathematics academic achievement' that can be confirmed through the results needs to moderate negative emotions to improve mathematical academic achievement, and at this time, negative motivation should be considered together.