• Journal of Magnetics
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• 제2권1호
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• pp.12-15
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• 1997

Fe-(3∼6.5wt%) Si alloy powders having a high magnetic induction(Bs) and a low core loss value for high frequency use were obtained by an extractive melt spinning as well as a centrifugal atomization technique. Sintered core rings made by the rapidly solidified Fe-6.5wt% Si powders exhibited the high frequency magnetic properties : megnetic induction(B8) of 1.23 T, coercivity(Hc) of 0.12 Oe, relative permeability(${\mu}$a) of 6321, and core loss(W10/50) of 1.27 W/kg from the rings of 1.1 mm thick. The magnetic induction values were found to be almost identical to those of non-oriented Fe-6.5wt% Si steel sheet and double the value of 6.5wt% Si sheet prepared by the CVD technique. The high frequency core losses(W) up to 10 kHz(W10/10k) were measured to be competitive to those of grain-oriented Fe-6.5wt% Si steel sheet.

• 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.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국제학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.943-946
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• 1988

A simple method is proposed for determining the frequency response function G(j.omega.) of a system using a pair of characteristic M-sequences (maximum length linear feed back shift register sequence). When a characteristic M-sequence is sampled with q$_{1}$ and q$_{2}$ both of which are coprime with N, where N is the period of the M-sequence, the obtained pair of sequences have conjugate complex frequency spectrum. Making use of this fact, two charcteristic M-sequences having conjugate complex frequency spectrum are applied to a system to be measured. Since the magnitude of spectrium of M-sequence is known, the gain of G(j.omega.) is directly obtained from the Fourier transform of the system output. The phase of G(j.omega.) is obtained simply by taking the average of the two phases of output spectrum.

• ETRI Journal
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• 제34권4호
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• pp.641-644
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• 2012

The problem of sinusoidal parameter estimation at two channels with common frequency in white Gaussian noise is addressed. By making use of the linear prediction property, an iterative linear least squares (LLS) algorithm for accurate frequency estimation is devised. The remaining parameters are then determined according to the LLS fit with the use of the frequency estimate. It is proven that the variance of the frequency estimate achieves Cram$\acute{e}$r-Rao lower bound at sufficiently small noise conditions.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2011년도 후기공동학술대회 논문집
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• pp.75-75
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• 2011

This paper has been studied that ocean wave vibration power generator is composed of buoy and vibration generator to make effective use of ocean wave energy. We designed buoy to can occur resonance for dominant frequency with ocean wave. And then we fitted the natural frequency of vibration system with vibration power generator to buoy's natural frequency. And we can show that the amplitude of ocean wave up and down motion is decreased, on the other hand, the displacement of vibration system with vibration power generator is increased. Therefore, ocean wave vibration power generator which is proposed in this paper has merits not only securing its stability from surroundings but also producing more electronic power by using ocean wave energy.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2004년도 추계학술발표회 논문집
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• pp.81-86
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• 2004

GPS surveying is being applied in earnest in public and construction surveying field recently. However only large enterprise surveying companies have GPS equipments but almost of small companies don't have them because of that their financial status is always too poor to purchase the expensive equipments such as Dual frequency GPS receiver. This is caused by some misunderstanding that only Dual frequency GPS receiver can be used for Public surveying. In order to increase the use of Single frequency GPS receiver to achieve competitive power of small companies in future, we need to verify the applicability and recommend surveyors to use it.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.153-156
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• 2000

To reduce the maintenance expense, and the possibility of electric outage and accident, we should optimize the outdoor insulation system. And for the optimization, accurate measurement for the degree of contamination with climatic conditions, such as wind, rain, and drought, should be carried. However the classical measuring method, brush wiping, has some problems in the aspect of man power, reliability, and expense. In this paper, we propose two type apparatus, which could detect the degree of contamination on insulators in outdoor insulation system, such as transmission and distribution line insulator and bushing. One use the leakage current, and the other use the oscillating frequency to check the degree of contamination. To avoid the oxidation of electrode AC source, and the low degree of contamination was applied. From the result of this investigation we could get the good relationship between the degree of contamination and the leakage current and oscillating frequency

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(1)
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• pp.587-593
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• 1996

Vibration analysis is one of the most powerful tools available for the detection and isolation of incipient faults in mechanical systems. The methods of vibration analysis in use today and under continuous study are broad band vibration monitoring, time domain analysis, and frequency domain analysis. In recent years, great interest has been generated concerning the use of time-frequency representation and its application for a machinery diagnostics and condition monitoring system. The objective of the research described in this paper was to develop a new diagnostic tool for the rotating machinery. This paper introduces a new time-frequency representation, Directional Wigner-Ville Distribution, which analyses the time- frequency structure of the rotating machinery vibration.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 춘계학술대회
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• pp.893-895
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• 2014

무선통신기반 열차제어시스템의 국내 도입을 앞두고 철도전용 주파수 할당에 대한 사항이 활발히 논의되고 있다. 공공자원으로서 큰 가치를 지닌 주파수를 적절한 용도에 알맞은 양을 할당하는 것은 다른 분야와의 형평성과 한정된 자원의 유용한 사용 측면에 있어서도 중요한 문제이다. 본 논문에서는 무선통신기반 열차제어시스템에서 기존에 논의되던 서비스들을 LTE 기반의 철도통신망에 적용했을 때 안정적인 운용이 가능한지에 대하여 시뮬레이션을 통하여 알아보았다.

• 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.