• 전자공학회논문지SC
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• 제47권6호
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• pp.1-5
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• 2010

본 논문에서는 PI 제어기를 설계해야 하는 경우인 임계 주파수 부근에서 이득 감소가 적은 시스템을 구별할 수 있는 알고리즘을 제안하였다. 임계 주파수 부근에서 이득감소가 적은 시스템을 구별하기 위해 시간 지연 요소를 이용하여 이득 감소율을 구하는 방법을 제안하였다. 또한 크기 마진과 위상 마진이 주어진 경우 PI 제어기를 설계하는 방법을 제안하였다. 제안된 알고리즘은 시간 지연요소와 포화함수를 이용하여 PI 제어가 가능한 한점의 좌표값을 계산하는 방법을 사용하였다. 제안된 방법은 시뮬레이션을 통해 타당성을 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.519-521
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• 2003

This paper presents a frequency analysis of subspan oscillation on overhead transmission line. The Oscillation frequency is a natural characteristic of a subspan and can be calculated. But it is not same to calculated frequency, because it has been composed several frequencies of adjacent subspan. We were analyzed to the frequency of subspan oscillation by FFT methods. This result will use to establish of the subspan location rules.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1987년도 춘계학술발표회 논문집
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• pp.201-205
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• 1987

In FH-SS systems when the bopping band is enough wide to onerlap with conventional band limited communication cethod (CBM). The portion of suchacts as an interfering signal. Thus it is gard to use them all together. This paper presents how the frequency gopping systems can simultaneously share the same band with CBM. The proposed mithod is that the frequency gopping band can arbitraily controlled by setting the specific input bith of digital frequency synthesizer to logical zero state We realized this by putting the hopping band Controller between pseudeo random generater and frequency synthesizer.

• 한국산학기술학회논문지
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• 제10권8호
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• pp.1832-1838
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• 2009

본 논문은 레이더의 펄스반복주기(PRI)를 포함한 각종 파라메타들을 비교하여 주파수 급속변경 레이더 신호를 식별하는 전자전 장비의 알고리즘에 관한 연구이다. 일반적으로 레이더는 단일주파수의 반송파를 사용하여 표적을 탐지하여 왔으나 최신 레이더들은 전자보호 기능을 강화하기 위해서 주파수 급속변경 반송파를 많이 사용하고 있다. 단일 주파수 사용 레이더 신호들이 전자전 장비에 수신되면, 전자전 장비는 레이더의 방위, 주파수, 펄스폭을 분석하여 레이더의 위치와 종류를 식별하였다. 그러나 주파수 급속변경 레이더인 경우에는 주파수가 비주기적으로 변경되므로 주파수를 레이더의 식별요소로 사용하는 것이 부적당하다. 따라서 본 논문에서는 Linked-List and Queue 방식으로 레이더 신호 요소들을 배치하여 레이더의 PRI를 구한 후에, PRI를 포함한 다수 파라메타들을 비교하여 주파수 급속변경 레이더를 식별하는 방법을 제안하였다. 제안된 알고리즘은 주파수 급속변경 레이더 신호를 포함한 레이더 신호의 분리가 매우 양호하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
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• pp.36-43
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• 2001

In Korea, we are absolutely short of earthquake data in good quality from moderate and large earthquakes, which are needed fur the study of strong ground motion characteristics. This means that the best use of the available data is needed far the time being. In this respect, several methods are suggested in this paper, which can be applied in the process of data selection and analysis. First, it is shown that the calibration status of seismic stations can be easily checked by comparing the spectra from accelerometer and velocity sensor both of which are located at the same location. Secondly, it is recommended that S/N ratio in the frequency domain should be checked before discarding the data by only look of the data in time domain. Thirdly, the saturated earthquake data caused by ground motion level exceeding the detection limit of a seismograph are considered to see if such data can be used for spectrum analysis by performing numerical simulation. The result reveals that the saturated data can still be used within the dominant frequency range according to the levels of saturation. Finally, a technique to minimize the window effect that distorts the low frequency spectrum is suggested. This technique involves detrending in displacement domain once the displacement data are obtained by integration of low frequency components of the original data in time domain. Especially, the low frequency component can be separated by using discrete wavelet transform among many alternatives. All of these methods mentioned above may increase the available earthquake data and frequency range.

• 한방재활의학과학회지
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• 제28권1호
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• pp.33-51
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• 2018

Objectives The purpose of this study is to analyze the current status of measurement instruments used to evaluate pain and function for shoulder disease patients in Korean Medicine clinical studies published in South Korea. Methods 5 Korean online databases from January 2007 to July 2017 were used to source articles for the review. Data of pain and function assessment instruments, measurement methods, time point and frequency for shoulder assessment were extracted. And it was analyzed by investigating the frequency of use for each item. Results A total of 78 studies met the selection criteria. There were many studies with no description for pain assessment instruments or inconsistent measurement methods. In the function assessment, the frequency of use was low and there were a lot of use of instruments with low validity and reliability. Conclusions To develop the objectivity of clinical research, further clinical studies, active use of measurement instruments, and standardization of measurement methods are needed.

• Journal of Computing Science and Engineering
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• 제6권2호
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• pp.79-88
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• 2012

Power continues to be a driving force in central processing units (CPU) design. Most of the advanced breakthroughs in power have been in a realm that is applicable to workstation CPUs. Advanced power management systems will manage temperature, dynamic voltage scaling and dynamic frequency scaling in a CPU. The use of power management systems for microcontrollers and embedded CPUs has been modest, and mostly focuses on very large scale integration (VLSI) level optimizations compared to system level optimizations. In this paper, a dynamic frequency controlling (DFC) technique is introduced, to lay the foundation of a system level power management system for commercial microcontrollers. The DFC technique allows a commercial microcontroller to have minor modifications on both the hardware and software side, to allow the clock frequency to change to save power; results in this study show a 10% savings. By adding an additional layer of software abstraction at the interrupt level, the microcontroller can operate without having knowledge of the current clock frequency, and this can be accomplished without having to use an embedded operating system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.255-257
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• 1994

The V/F slip frequency constant control methods are used for driving induction motor with load commutated current source inverter, that is. constant V/F and slip frequency driving is used to load commutate the inverter below the critical frequency, while constant voltage and variable frequency and slip frequency driving are used in above the critical region. In order to applicate the load commutated current source inverter to the general use, speed control range of induction noter is selected to two times at rated frequency. Therefore, economical application is possible because of the maximum reduction of the condenser of the inverter output port. The use of the proposed force commutated circuit improves the false operation of force commutated circuit and inverter commutation failure which are produced by the influence of the lower-order harmonics of the conventional load commutated current source inverter at starting.

• 한국전자통신학회논문지
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• 제10권1호
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• pp.33-38
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• 2015

본 논문은 한글부호의 전송을 최적화하는데 요구되는 한글낱자를 연구하였다. 한글낱자는 한국어를 구성하고 있는 한글을 토대로 하여 분석하였다. 한글낱자의 분석은 세가지 유형을 대상으로 하여 수행하였다. 첫번째 대상은 한글맞춤법 통일안의 24개 낱자이었다. 두번째 대상은 표준 두벌식 글자판의 낱자 28개이었다. 세 번째 대상은 한글맞춤법 통일안에 겹낱자를 포함한 총 54개 낱자이었다. 이 세가지 분석대상별로 각 낱자에 대한 사용빈도를 분석하였다. 국립국어원의 한국어자료에 수록된 총 한국어 단어는 총58,437개인데, 단어들은 총 1,540자의 글자로 구성되어 있다. 이 한글들을 분석한 결과, 사용빈도수를 보면, 첫 번째 대상의 경우, 닿소리는 "ㅇ"이 가장 많고 "ㅋ"이 가장 적었으며 홑소리는 "ㅏ"가 가장 많고 "ㅑ"가 가장 적었다. 두 번째 대상의 경우, 닿소리는 첫 번째 대상과 같고 홑소리는 "ㅏ"가 가장 많고 "ㅒ"가 가장 적었다. 세 번째 대상의 경우, 닿소리는 "ㄱ"이 가장 많고 "ㄽ"이 가장 적었으며 홑소리는 "ㅏ"가 가장 많고 "ㅞ"가 가장 적었다.

• 아시아태평양코퍼스연구
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• 제1권2호
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• pp.57-72
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• 2020

This study seeks to add to the current understanding of learners' use of modality in argumentative writing. A learner corpus of argumentative essays on four topics was created and compared to native English speaker data from the International Corpus Network of Asian Learners of English (ICNALE). The relationship between learners' use of modal devices (MDs) and the devices' appearance in the school's curriculum was also examined. The results showed that learners relied on a very narrow range of MDs compared to those in previous studies. The frequency of use of MDs varied based on the topic and did not seem to be driven by cultural factors as has been previously suggested. Learners used more hedges than boosters on all topics, contradicting most previous studies. Curriculum was determined to have a direct correlation with MD use, and other important factors may include perception of topic and overreliance on certain MDs over others (the One-to-One principal). This research implies that learners' perception of topic should be explored further as a variable affecting MD use. Curricula should be designed based on frequency of MD use by English native speakers, and learners should receive instruction that teaches the norms of MD use in academic writing. The methodology used in the study to determine correlations between MD use and the curriculum has a wide range of potential applications in the field of Contrastive Interlanguage Analysis.