• Title/Summary/Keyword: frequency problem

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Development of Supply Capability Calculation and Prediction Technology for Generator (발전기 공급능력 산정 및 예측 기술개발)

  • Kim, Euihwan;An, Youngmo;Hong, Eunkee
    • KEPCO Journal on Electric Power and Energy
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    • v.2 no.3
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    • pp.425-431
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    • 2016
  • Supply Capability of the generator, if the maximum demand occurs, refers to the maximum power that can be stably supplied and it is possible to maintain stable power supply to be greater than actual load. However, unexpected power demand and reduction in supply Capability due to stop of unexpected generator in operation can temporarily make a big chaos in power system. In fact, due to a lack of power supply Capability in the country, enforced emergency load adjustment to the September 15, 2011, the circulation power outage has occurred in several cities. As the result, interrupted operation of the elevator and stopped hospital medical equipment led to a great deal of trouble to people's lives, causing a social problem. At that time, it was found that a failed frequency control because of smaller actual supply Capability than that of predicted. The difference was about 1,170 MW with Gas turbine power plant. By accurately calculating the generator supply capability, we can not only grasp the power reserve rate, but also correspond to the time of power supply instability.

Performance Analysis of a Korean Word Autocomplete System and New Evaluation Metrics (한국어 단어 자동완성 시스템의 성능 분석 및 새로운 평가 방법)

  • Lee, Songwook
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.6
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    • pp.656-661
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    • 2015
  • The goal of this paper is to analyze the performance of a word autocomplete system for mobile devices such as smartphones, tablets, and PCs. The proposed system automatically completes a partially typed string into a full word, reducing the time and effort required by a user to enter text on these devices. We collect a large amount of data from Twitter and develop both unigram and bigram dictionaries based on the frequency of words. Using these dictionaries, we analyze the performance of the word autocomplete system and devise a keystroke profit rate and recovery rate as new evaluation metrics that better describe the characteristics of the word autocomplete problem compared to previous measures such as the mean reciprocal rank or recall.

A review of cognitive orientation to daily occupational performance with stroke

  • Ahn, Si-Nae
    • Physical Therapy Rehabilitation Science
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    • v.6 no.4
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    • pp.202-207
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    • 2017
  • Objective: The self-decisions of the client regarding the meaningful work as a therapeutic approach of client-orientation. The Cognitive Orientation to daily Occupational Performance (CO-OP) is an occupation-oriented problem-solving approach. The purpose of this study was to describe the goals and intervention protocols of CO-OP in those affected by stroke. Design: A systematic review. Methods: Using EBSCOhost, PubMed, and ProQuest databases, we searched studies published in the past decade that utilized the CO-OP intervention. An initial search revealed 71,171 potential articles. After applying our search criteria to screen the titles, abstracts, and full-text, we included 7 articles that met our inclusion and exclusion criteria. In this study, we used the patient, intervention(s), comparison, outcome method to analyze the 7 selected studies. We analyzed the frequency of goals and intervention protocols. Results: Seven articles met our selection criteria; these studies included participants with an almost normal cognitive function from inpatient and outpatient rehabilitation facilities. CO-OP was used for 237 goals; the most used goal was the instrumental activities of daily living. The training procedure used 3 types of self-selecting goals in the activities. One of the goals was not trained, but was only evaluated to determine the generation effect. The most common outcome measurements included the Canadian Occupational Performance Measure and the Performance Quality Rating Scale. Conclusions: This research provided information about the effectiveness of CO-OP and selecting the correct evaluation tool to assess the efficiency of the intervention. This study suggests that treatment with CO-OP in occupational therapy is effective and that it outlines common protocols.

Vortex Shedding Frequency for a 2D Hydrofoil with a Truncated Trailing Edge (뒷날이 잘린 2차원 수중익의 와도 흘림 주파수)

  • Lee, Seung-Jae;Lee, Jun-Hyeok;Suh, Jung-Chun
    • Journal of the Society of Naval Architects of Korea
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    • v.51 no.6
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    • pp.480-488
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    • 2014
  • Vortex shedding which is the dominant feature of body wakes and of direct relevance to practical engineering problems, has been intensively studied for flows past a circular cylinder. In contrast, vortex shedding from a hydrofoil trailing edge has been studied to much less extent despite numerous practical applications. The physics of the problem is still poorly understood. The present study deals with $K{\acute{a}}rm{\acute{a}}n$ vortex shedding from a truncated trailing-edge hydrofoil in relatively high Reynolds number flows. The objectives of this paper are twofold. First, we aim to simulate unsteady turbulent flows past a two dimensional hydrofoil through a hybrid particle-mesh method and penalization method. The vortex-in-cell (VIC) method offers a highly efficient particle-mesh algorithm that combines Lagrangian and Eulerian schemes, and the penalization method enables to enforce body boundary conditions by adding a penalty term to the momentum equation. The second purpose is to investigate shedding frequencies of vortices behind a NACA 0009 hydrofoil operating at a zero angle of attack.

Large-Scale Structure of Leading-Edge Separation Bbubble with Local Forcing (국소교란이 가해지는 박리기포의 대형구조)

  • 김유익;성형진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.4
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    • pp.1134-1147
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    • 1995
  • POD (proper orthogonal decomposition) is applied to turbulent leading-edge separation bubble to extract coherent structures. A two-dimensional leading-edge separation bubble is simulated by discrete-vortex method, where a time-dependent source forcing is incorporated. Based on the wealth of numerical data, POD is applied in a range of the forcing amplitude ( $A_{o}$ = 0, 0.5, 1.0 and 1.5) and forcing frequency (0 .leq. $f_{F}$H/ $U_{\infty}$.leq. 0.3). It is demonstrated that the structures of POD have noticeable changes with local forcings. In an effort to investigate the mechanism of decreasing reattachment length, dynamic behaviors of the expansion coefficients and contributions of the eigenfunctions of POD are scrutinized. As the forcing amplitude increases, the large-scale vortex structures are formed near the forcing amplitude increases, the large-scale vortex structures are formed near the separation point and the flow structures become more organized and more regular, accompanying with the reduction of reattachment length. By further inverstigation of POD global entropy, it is seen that the reattachment length is closely linked to the degree of organization of the flow structures.es.s.

Modeling and Design Algorithm of Conducted EMI Filter Using a Noise Separation Method (노이즈 분리 기법을 이용한 진도EMI 필터의 모델링 및 설계 알고리즘)

  • 정용채
    • The Transactions of the Korean Institute of Power Electronics
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    • v.9 no.3
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    • pp.260-266
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    • 2004
  • Because the EMI filter is mainly designed by trial and error method, it takes many times to reduce the conducted EMI noise in a power converter. Thus, a newly analytical design procedure is proposed to overcome the problem in this paper. High frequency models of each component are built, md, using the modeling circuits, the filter design is carried out applicable to each mode. Based on the accumulated database for practical components, and the measurement data of EUT with a standard filter, the filler design algorithm is presented. Finally, the validity of the Proposed models and design method is verified through the measurement results.

Application of the B-Spline Based High Order Panel Method to the Floating Body Dynamics (B 스플라인 고차 패널법을 적용한 부유체 운동해석)

  • Ahn, Byoung-Kwon;Lew, Jae-Moon;Lee, Hyun-Yup;Lee, Chang-Sup
    • Journal of Ocean Engineering and Technology
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    • v.22 no.5
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    • pp.25-30
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    • 2008
  • A B-spline based high order panel method was developed for the motion of bodies in an ideal fluid, either of infinite extent or with a free boundarysurface. In this method, both the geometry and the potential are represented by the B-spline, which guarantees more accurate results than most potential based low order methods. In the present work, we applied this B-spline based high order method to the radiation problem of floating bodies. The boundary condition on the free surface was satisfied by adopting a Kelvin-type Green function and irregular frequencies were removed by placing additional control points on the free surface surrounding the body. The numerical results were validated by comparison with existing numerical and experimental results.

A Study on the Adaptive Dress for the Disabled Ederly(2) - Nursing Facilities for the Ederly in Seoul and KyoungIn Area - (거동 불편 노인에 대한 기능성 의복 연구(2) - 서울, 경인 지역 노인 전문 요양 시설을 중심으로 -)

  • 홍나영;지윤영
    • The Research Journal of the Costume Culture
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    • v.8 no.6
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    • pp.899-914
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    • 2000
  • The purpose of the study was to provide the actual data for designing adaptive dresses for the disabled elderly. In order to get the data, we had 3 parts of the procedure as follows ; 1. The survey of 205 nursing-care providers who take care of the disabled elderly in 1999. 2. Measuring 10 measurements of 80 disabled men and women each, 160 samples. 3. On the basis of data above, developing the adaptive dresses and doing the wearing-tests of those. The results are as follows ; 1. The most popular style for the disabled elderly in nursing facilities was non-collar pajama's. Specially, pajama style was needed for the disabled elderly being sick in bed, one-piece style was required for the disabled eldery with dementia. And the most desirable fabric function was a physiological comfortability. The most proper price required was about 20,000 won. 2. As Korean apparel industry use K.S. sizing system, we decided to use the same measurement to categorize the samples, bust and height. And according to the frequency in the size chart, we suggested the production size for the disabled eldery men and women. 3. After developing these adaptive dresses, the results of wearing-tests showed two kinds of problems. One was that of the sleeve length ; Actually, for the disabled elderly, the longer than the production size is the better for them. The other problem was revealed from subsidiay materials, fasteners.

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Filter Design to Eliminate Motion Artifact of Pulse Oximetery (펄스 옥시메터의 동잡음 제거 필터 설계)

  • 이주원;이종희;강익태;김경하;이건기
    • Journal of Biomedical Engineering Research
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    • v.22 no.5
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    • pp.431-438
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    • 2001
  • Oxygen saturation of blood is defined as ratio of total hemoglobins density to oxyhemoglobins density And the accuracy of pulse oxymeter that measures the oxygen saturation of blood by a noninvasive method is influenced by a measuring environment, breathing and motion of patient. Especially when patient moved his arms and fingers, it is difficult to eliminate motion artifact because the motion artifact signal has features that are overlap or closed at normal signal in frequency domain. We propose the filtering method that construct the filter banks and a matched falter to improve the Problem. When experimented by the proposed method, the ratio regulation of the proposed methods has 4.1% below than an adaptive filter (39.7%) and a moving average filter (11.2%). So. the Proposed method will be able to get a stable ratio of SpO2.

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A study on the application and counter measures of IC tag in international marine container transport (국제해상컨테이너운송에서 보안강화를 위한 전자태그(IC tag)의 적용과 대응방안)

  • Han, Sang-Hyun;Choi, Jun-Ho
    • International Commerce and Information Review
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    • v.12 no.2
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    • pp.133-158
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    • 2010
  • Since 11 September 2001, the awareness of terrorists' actions has clearly risen. The potential threat of terrorists using containers poses a large risk to our economies and to our societies. In order to protect cargo from damage and terrorist threats, business and government turn to RFID and IC tags, and tradition container is replaced by IC smart container. In this study, presented application of IC tag and future tasks to Container transport by sea in viewpoint of security strengthening. First, realization and international SCM realization structural order that cover container supply chain whole of international standardization and association between industry are certainly needed. Second, it may have to try in technical development for IC tag Ratio that can read elevation moment develop suitable IC tag or reader in International Standard. Third, Need to establish concrete use policy as soon as possible in national dimension at the same time effort for international standard normalization of frequency. Finally, it shows to uses jointly with electron sealing and must solve problem about usable plan and information leak.

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