• 제목/요약/키워드: Power quality improvement

검색결과 582건 처리시간 0.033초

친환경절연재의 절연성 평가 (Assess of Breakdown Characteristics about Environmentally Friendly Gases)

  • 최은혁;구본호;김이국;이광식
    • 조명전기설비학회논문지
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    • 제23권5호
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    • pp.96-100
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    • 2009
  • 산업사회의 발달과 더불어 신뢰성 높은 양질의 전기에너지와 운전 및 보수의 간편화, 계통 운용의 신뢰성, 안전성 확보가 요구되고 있다. 따라서 본 논문은 각종 전력설비에서 $SF_6$을 대체할 수 있는 친환경절연제로 연구되고 있는 $N_2-O_2$ 혼합가스($N_2:O_2=100$ : 0, 79 : 21, 60 : 40, 40 : 60) 절연파괴특성을 구명(究明)하여 이를 $SF_6$가스의 특성과 비교하였다. 이상의 연구 결과, 제조공기와 Dry-Air 절연특성을 구명함으로서 각종 전력응용 설비의 절연설계에 $SF_6$ 대신 친환경적인 모의공기를 사용 가능함을 본 연구에서 구명(究明)하였다. 제조공기를 이용한 친환경적인 절연재 사용으로 지구의 온난화현상 감소에 크게 기여할 것으로 기대된다.

주얼리CAD와 RP 장비를 이용한 주얼리제작 활용방안 (Plan of Jewelry Product Application Using Jewelry CAD and RP Equipment)

  • 김문배
    • 한국콘텐츠학회논문지
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    • 제7권12호
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    • pp.66-73
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    • 2007
  • 주얼리 관련 산업은 국내 시장의 불황, 디자인 개발 부재, 기능 인력의 부재와 높은 인건비 부담으로 고민에 처해 있다. 또한 소비자들의 가격대비 최대한의 가치를 가진 차별화된 제품을 원하고 있다. 주얼리 CAD와 RP 장비는 수작업에 의존했던 주얼리 제조업체에게 생산성을 단축시켜주고 다양한 디자인과 빠른 신제품을 제공해 줄 수 있다. 하지만 아직까지 RP에서 출력된 합성 수지의 직접 주조의 어려움으로 원본 작업에 필요한 만큼의 최상의 주조 소환 사이클을 알지 못하는 상태이다. 이에 본 연구자는 CAD의 활용성과 RP 장비에 관하여 분석하고, 주얼리 CAD 작업과 RP 작업을 통하여 직접 주조가 가능하도록 주조 소환 사이클을 분석하여 원본 제작에 적합한 제품을 제작할 수 있었다. 이 논문을 통해 주얼리 제품의 질적 향상과 차별성을 확보하여 다양하고 경쟁력 있는 디자인과 제품 생산에 새로운 기반을 제공하는 것에 의의를 찾고자 한다.

수정된 강제 유도 운동치료와 결합된 이중 반구 경두개 직류 자극이 만성 뇌졸중의 팔 기능에 미치는 영향 : 단일 맹검 무작위 통제 시험 (Impact of Dual-Hemisphere Transcranial Direct Current Stimulation Combined with Modified Constraint-Induced Movement Therapy on Upper Limb Function in Chronic Stroke: A Single Blinded Randomized Controlled Trial)

  • 김선호
    • 대한통합의학회지
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    • 제8권2호
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    • pp.11-20
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    • 2020
  • Purpose : The purpose of this study was to research the effects of dual-hemisphere transcranial direct current stimulation (dual tDCS) and modified constraint-induced movement therapy (mCIMT) to improve upper extremity motor function after stroke. Methods : The study period was from August 2019 to November 2019, and included 24 patients who met the selection criteria. Participants were divided into 2 groups: dual tDCS and mCIMT, and sham dual tDCS and mCIMT group. Dual tDCS and mCIMT group performed mCIMT immediately after applying dual tDCS for 20 minutes, and sham dual tDCS and mCIMT group performed mCIMT immediately after applying sham tDCS for 20 minutes without turning on the power source. Total interventions were conducted 5 times per week for 4 weeks, and mCIMT was conducted for 30 minutes per session for both experimental and control groups. Fugl-Meyer assessment (FMA) and Motor Activity Log scale (MAL) were analyzed before and after 4 weeks of intervention. Results : Both experimental and control groups showed significant changes in FMA, Amount of Use (AOU), and Quality of Movement (QOM) of MAL. When the differences between groups was compared using ANCOVA, the experimental group showed a greater improvement in FMA and AOU of MAL than the control group. Conclusion : In order to enhance the effect of improving upper limb function of stroke patients, dual tDCS could be applied to provide more effective treatment in the clinical setting. Further studies will be needed in larger groups of stroke patients, including long-term follow-up, and multi-group comparisons through the establishment of anodal tDCS and mCIMT, cathodal tDCS, and mCIMT groups to clarify the effects of dual tDCS. In addition, research is needed to establish a protocol for tDCS, and this evidence-based intervention protocol is expected to be used in the clinical setting as an interventional method for various purposes.

원형 배열 안테나의 DoA 추정 알고리즘 성능 분석 (Performance analysis of DoA estimation algorithm using a circular array antenna)

  • 임승각;강대수
    • 한국산학기술학회논문지
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    • 제9권2호
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    • pp.395-400
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    • 2008
  • 본 논문은 GPS 신호를 수신할 때 재머신호의 제거를 위한 성능 개선을 목적으로 2차원 원형 배열 안테나를 이용한 도래각(DoA : Direction of Arrival) 추정 알고리즘의 성능 분석에 관한 것이다. 배열 안테나를 사용하여 DoA를 추정한 후 공간 필터링을 수행함으로서 원하지 않는 방향으로부터의 재머신호를 널링(nulling)시키고, 원하는 방향으로의 빔을 형성하므로서 수신 신호의 품질을 개선할 수 있다. 논문에서는 4 소자와 7 소자 원형 배열 안테나에서 재머신호의 각도와 전력을 고정시킨 후 DoA 추정을 위하여 MUSIC, MinNorm 알고리즘을 적용한다. 이들 알고리즘의 성능 분석을 위하여 추정 결과와 추정 오차를 컴퓨터 시뮬레이션을 통하여 계산한다. 추정 결과 신호대 잡음비가 양호한 경우 Azimuth각과 Elevation각 추정에서는 MUSIC과 MinNorm이 우월하며, 신호대 잡음비가 낮은 경우 MUSIC이 MinNorm보다 우월한 성능을 보인다.

어장·어촌과 연계한 지방어항건설사업의 평가분석 (The Evaluation Analysis of the Local Fishing Port Construction Project in Connection with Fishery and Fishing Village)

  • 신승식;박주삼
    • 수산해양교육연구
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    • 제20권3호
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    • pp.369-380
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    • 2008
  • The government has promoted the local fishing port construction project since 1972 for conquest of the crisis of the fishing village by withering of a fishery, the improvement in fishermen's living environment and quality of life, and promotion of fisheries. In order to estimate the local fishing port construction project objective and synthetically, and to grope for the method proposal of system establishment of the project, the monitoring survey was carried out. The monitoring survey was classified into the program and the performance monitoring. The program monitoring was carried out in order to investigate the project fit for the inhabitants of a fishing village. The performance monitoring was carried out in order to investigate the development latent powers, fishery latent powers, tourism latent powers of a fishing village, rural settlement conditions, etc. using various statistical materials. Since investigating the measured value before executing a policy was not completed, the project effect was compared with the measured value of other areas. According to the local fishing port construction project, the development latent powers, fishery latent powers, and tourism latent powers of the fishing village where the project was undertaken improved greatly, and income of the fishing village increased greatly. As a result of comparing project fit in order to evaluate the project, the project fit of the local fishing port construction project area was higher than the non-project area. Desirable method proposal of monitoring survey was established and the method for raising the efficiency of monitoring survey was extracted.

고급차의 제동 신뢰성 향상을 위한 카본 세라믹 복합재의 제동 특성 제어 및 향후 기술 진화 트랜드 예측에 관한 연구 (A Study on Braking Characteristics Control of Carbon Ceramic Composite for Brake Reliability Improvement of Luxury Car and Future Technology Evolution Trend Prediction)

  • 심재훈;전갑배;이중희;박병준;임동원;현은재;정광기;김기정;김홍기
    • 한국자동차공학회논문집
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    • 제24권6호
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    • pp.684-693
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    • 2016
  • The luxury car industry has grown 10.5 % every year from 2010 to 2014. For this reason, it is very important for automotive companies to improve profitability and brand value. High-performance brake systems have become an absolute necessity because of the increase in engine power and customer preference among other factors. Also, competing automotive companies actively reinforce domestic production in order to maintain quality and infrastructure for luxury cars. In this regard, we demonstrated new carbon ceramic brakes to improve brake reliability for luxury cars and to improve the competitiveness of automotive companies. Finally, we propose the next-generation braking technology by predicting technological evolution trends.

Performance Analysis of Co- and Cross-tier Device-to-Device Communication Underlaying Macro-small Cell Wireless Networks

  • Li, Tong;Xiao, Zhu;Georges, Hassana Maigary;Luo, Zhinian;Wang, Dong
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제10권4호
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    • pp.1481-1500
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    • 2016
  • Device-to-Device (D2D) communication underlaying macro-small cell networks, as one of the promising technologies in the era of 5G, is able to improve spectral efficiency and increase system capacity. In this paper, we model the cross- and co-tier D2D communications in two-tier macro-small cell networks. To avoid the complicated interference for cross-tier D2D, we propose a mode selection scheme with a dedicated resource sharing strategy. For co-tier D2D, we formulate a joint optimization problem of power control and resource reuse with the aim of maximizing the overall outage capacity. To solve this non-convex optimization problem, we devise a heuristic algorithm to obtain a suboptimal solution and reduce the computational complexity. System-level simulations demonstrate the effectiveness of the proposed method, which can provide enhanced system performance and guarantee the quality-of-service (QoS) of all devices in two-tier macro-small cell networks. In addition, our study reveals the high potential of introducing cross- and co-tier D2D in small cell networks: i) cross-tier D2D obtains better performance at low and medium small cell densities than co-tier D2D, and ii) co-tier D2D achieves a steady performance improvement with the increase of small cell density.

중국 ${\ll}$무역백서(中国的对外贸易)${\gg}$의 주요내용 및 한국기업의 대응책 (Major Contents and Proposal for "China's Foreign Trade")

  • 송수련
    • 무역상무연구
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    • 제61권
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    • pp.327-358
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    • 2014
  • During the past decade after entering the World Trade Organization (WTO), China has quickened its integration into the global economy while its foreign trade has been further invigorated. On the 10th anniversary of China's accession to the WTO, the Chinese government issues White Paper to give a comprehensive introduction to China's foreign trade development. Through this paper, the Chinese government introduces I. Historic Progress in China's Foreign Trade II. Reform of and Improvements to China's Foreign Trade System III. The Development of China's Foreign Trade Contributes to the World Economy IV. Promoting Basically Balanced Growth of Foreign Trade V. Constructing All-round Economic and Trade Partnerships with Mutually Beneficial Cooperation VI. Realizing Sustainable Development of Foreign Trade. At present, the underlying impact of the international financial crisis, the protracted, arduous and complicated nature of the world economic recovery is manifesting itself, and the global economic structure and trade layout face in-depth readjustment. China will make new adjustments to its foreign trade, in an effort to turn foreign trade from scale expansion to quality and profit improvement, and from mainly relying on its low-cost advantage to enhancing its comprehensive competitive edge, thereby turning China from a big trading country to a strong trading power. China's foreign trade is still hampered by many uncertainties and is bound to meet new difficulties and challenges. During the 12th Five-year Plan period China will open itself wider to the outside world as a driver for further reform, development and innovation, make full use of its advantages, strengthen international cooperation in all respects. And at the same time China integrate itself into the world economy on a wider scale and at a higher level. China is willing to work with its trading partners to cope with the various challenges facing the world economy and trade, and promote its foreign trade to realize a more balanced, coordinated and sustainable development, and share prosperity and mutually beneficial results with its trading partners.

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Review on improving measurement of cyber terror management system

  • Park, Jong-Ryeol;Noe, Sang-Ouk
    • 한국컴퓨터정보학회논문지
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    • 제21권6호
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    • pp.89-96
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    • 2016
  • Damage and attack size of cyber terror is growing to the national size. Not only targeting at a certain companies or individuals but number of cyber terror targeting government bodies or unspecific people is increasing. This is because compared to traditional weapon, input cost is very cheap but ripple effect and shock are much stronger, affecting not only certain groups but also each individuals. 'Anti-terror measurement for protection of nation and public safety' passed last month is one of the renowned measurement passed regardless of objection from opposition party. The opposition party went against this through filibuster for 192 hours but this finally passed National Congress due to lack of oppositions. Korean government is taking post actions after passage of anti-terror measurement. Legislation of enforcement ordinance and regulations is due by 6th of next month. This regulation will be executed from June 4th after legislation. Whenever there is any security issues such as hacking of Korea Hydro and Nuclear Power and National Intelligence Service happens, lot of attention is made to those hackers. However, social recognition or management of those hackers need lot more improvement. Especially, as market of internet of things is increasing, there is an increased anxiety on information security. But as we only rely on security solutions, this problems are keep happening. Therefore, active investment on nurturing hackers who play the role of 'spear and shield' shall be made. Government should put more efforts to allow white hackers to show their abilities. We should have a policy for supporting high-quality programs such as BoB. To make information protection industry into future growth engine, it is necessary to nurture professionals for information protection and white hackers through special programs. Politicians should make related regulations as soon as possible to remove factors that prevent swift management of cyber attack due to lack of legislation. Government should pay lot more financial investment to nurturing professional manpower than now. Protecting life and asset of nation is responsibility and duty of our government. We all should recognize that controlling cyber attack is a part of national defense.

마이크로폰 어레이를 위한 적응 모드 컨트롤러 (Adaptation Mode Controller for Adaptive Microphone Array System)

  • 정양원;강홍구;이충용;황영수;윤대희
    • 한국통신학회논문지
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    • 제29권11C호
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    • pp.1573-1580
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    • 2004
  • 본 논문은 실제 환경에서 고품질 음성 신호 취득을 위해, 적응 마이크로폰 어레이 시스템을 위한 적응 모드 컨트롤러를 제안한다. 적응 어레이 알고리즘의 올바른 동작을 위하여, 제안된 적응 모드 컨트롤러는 시간 축의 정보뿐만 아니라 공간 축의 정보를 함께 사용한다. 제안된 적응 모드 컨트롤러는 초기화 단계와 수행 단계의 두 단계로 나뉘어 동작되는데, 초기화 단계에서는 음원 위치 추정 기술이 사용되며, 수행 단계는 신호의 상관 관계 특성에 의해 동작한다. 적응 어레이 알고리즘으로는 적응 차단 행렬을 이용한 Generalized Sidelobe Canceller가 사용되었다. 제안한 적응 모드 컨트롤러는 적응 차단 행렬이 수렴되지 않은 경우에도 사용 가능하며, 기존의 전력비 방법에 비해 안정적인 성능을 나타낸다. 본 논문은 제안한 시스템을 실제 환경에서 평가하였으며, 2m 거리에 위치한 화자에 대해 13dB SINR 향상을 얻었다.