• 한국군사과학기술학회지
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• 제10권2호
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• pp.160-169
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• 2007

In this paper, we have described and simulated the effect analysis and correction of phase errors in the SAR rawdata induced by satellite attitude errors such as drift, jitter. This simulation is based on the FSA(Frequency Scaling Algorithm) for high resolution image formation of the Spotlight SAR. Phase errors produce the degradation of SAR image quality such as loss of resolution, geometric distortion, loss of contrast, spurious targets, and decrease in SNR. To resolve this problem, this paper presents method for correction of phase errors using the PGA(Phase Gradient Algorithm) in connection with the FSA. Several results of the phase errors correction are presented for Spotlight SAR rawdata.

• 전기학회논문지P
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• 제57권4호
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• pp.437-443
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• 2008

We have developed an evaluation technique for both ratio error and phase displacement of current transformer (CT) comparator by using the precise standard capacitors and resistors. By applying this technique to equivalent circuit of CT comparator evaluation system, we can obtain the calculated and measured ratio errors (or phase displacements) in the CT comparator. Thus we can evaluate ratio errors and phase displacement of CT comparator by comparing the calculated and measured ratio errors (or phase displacements). The method was applied to CT comparator under test with the ratio errors and phase displacement ranges of $0{\sim}{\pm}10%$ and $0{\sim}{\pm}7.5$ crad, respectively. Finally we have compared the ratio error and phase displacement of the CT comparator obtained in this method with specifications of two companies.

• 한국전자파학회논문지
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• 제25권8호
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• pp.864-871
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• 2014

본 연구에서는 Rotman 렌즈의 위상 오차를 최소화하는 빔 곡선을 구하는 최적화 방법을 제안하고 있다. 이 방법은 빔 포트로부터 배열안테나의 중심점과 배열안테나를 따라 대칭 또는 비대칭으로 놓인 두 개의 점으로 구성된 동위상점들을 통과하여 대응되는 동위상면까지의 3개의 경로길이는 동일하다는 개념에 근거를 두고 있다. 이 방법을 따르면, 각각의 빔 방향에 대하여 위상 오차를 최소화하는 배열안테나 상의 동위상점 집합을 찾으면 최적의 빔 포트 위치를 직접 구할 수 있다. 시뮬레이션 결과는 제안된 방법이 저 위상 오차를 갖는 Rotman 렌즈의 빔 곡선을 구하는 가장 최적이며 효과적인 방법임을 보여준다.

• 전기학회논문지
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• 제65권7호
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• pp.1204-1210
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• 2016

The phase currents must be accurately measured to achieve the instantaneous torque control of AC motors. In general, those are measured using the current sensors. However, the measured current signals can include the offset errors and scaling errors by several components such as current sensors, analog amplifiers, noise filter circuits, and analog-to-digital converters. Therefore, the torque-controlled performance can be deteriorated by the current measurement errors. In this paper we have analyzed the influence caused by vector control of 2-phase induction motor when two errors are included in measured phase currents. Based on analyzed results, the compensation method is proposed without additional hardware. The proposed compensation method was applied vector-controlled inverter for 2-phase induction motor of 360[W] class and verified through computer simulations and experiments.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2010년도 춘계 학술논문 발표대회 2부
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• pp.103-108
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• 2010

The purpose of this study is to analyze of the risk factors for oversea plants construction projects. For this study, risk factors data from related literature review, research organization and construction company was researched and classified under each EPC phases. In addition, a questionnaire survey by plant experts was conducted for analysis of risk weight and costs and time impact on each EPC phases. The results of this study are as follows: First, a detail design errors(engineering phase), a equipment procurement plan(procurement phase), and exchange rate fluctuations(construction phase) were analyzed the highest weight factors. Second, a financing plan(engineering phase), quantity take-off bill(procurement phase), and exchange rate fluctuations(construction phase) were analyzed the highest cost impact factors. Third, detail design errors(engineering phase), a equipment procurement plan(procurement phase), and schedule management errors(construction phase) were analyzed the highest time impact factors.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 춘계 학술논문 발표대회
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• pp.25-27
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• 2012

The domestic construction industry recognize that review of design and construct-ability has the devastating effects. The way to take advantage of BIM for increase the possibility of discovered the design errors in advance are being discussed a lot recently. Since 2012, Public procurement published that the Turn-key project which is the more than 50 billion won in construction have to let the BIM-based design be mandatory. However, people expected the advent of BIM technology can resolve the existing design errors. But the situation is the connection of design stage and construction stage is very insufficient in domestic. Therefore, in this study understanding the types of design errors in construction phase. according the review of design errors before construction. Then can acceleration the application of BIM to improve the workability in a construction site.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.513-516
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• 2003

Phase Measuring Profilometry(PMP) has been developed as one of three dimensional 3-D shape measuring methods. The 3-D profile of an object was calculated from the phase data obtained by the sinusoidal patterns projected on the object. However, in some cases the approximation includes considerable errors. In this paper, the effect on the errors caused by the optical geometry and the calibration procedure in PMP technique are discussed. The errors which occured in the process of calculating the 3-D profile from the phase distribution are investigated theoritically and experimentally.

• 한국광학회지
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• 제22권5호
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• pp.207-213
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• 2011

몬테카를로 방법을 기반으로 한 수치해석을 이용하여 AWG(arrayed waveguide grating)의 위상 오차를 측정하는 방법을 제안한다. 진동수 영역 측정법에서 실험치와 가장 근접한 이론치를 구하기 위해 몬테카를로 방법을 사용하며 최적화된 이론치로부터 AWG 각 도파로의 진폭과 위상값들을 결정한다. 이 방법의 타당성을 검증하기 위해 모의실험을 수행하였다. AWG의 각 도파로에 임의로 위상 오차를 설정하여 가상의 실험치를 만들고 우리의 방법을 통해 거꾸로 위상 오차를 알아냈다. 모의실험 결과 간섭계 광원의 진동수 변조 범위가 AWG FSR(free spectral range)의 1.7 배보다 클 때, 그리고 위상 오차가 ${\pm}50^{\circ}$ 이내일 때 매우 정확하게 위상 및 진폭을 측정할 수 있음을 확인하였다.

• 한국전자파학회논문지
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• 제17권12호
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• pp.1249-1258
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• 2006

ISAR 자동 초점(autofocus) 기법이란 움직이는 표적에 대한 2차원 레이더 영상인 ISAR 영상을 얻을 때 표적에 의한 doppler-shift 때문에 발생하는 위상 오차를 예측, 제거하는 기법이다. 이러한 자동 초점 기법이 수행되지 않은 ISAR 영상은 위상 오차(phase ewer)에 의한 왜곡이 포함되기 때문에 초점이 맞지 않는 것처럼 흐린(blurred) 영상이 된다. 이러한 영상은 추후에 구분기(classifier)를 이용하여 표적 구분 시 올바른 구분을 보장할 수 없으므로 반드시 자동 초점 기법이 수행되어야 하며, 본 논문에서는 이를 위해 영상의 엔트로피(entropy)를 최소화시키는 알고리즘을 이용한다. ISAR 자동 초점 기법은 크게 range alignment 과정과 phase adjustment 과정으로 나뉘는데, range alignment 과정에서 샘플링 포인트(sampling point)의 수와 그에 따른 영상 품질과의 관계를 분석하고, phase adjustment 과정 을 수행하기 위한 알고리즘인 SSA(Stage-by-Stage Approaching)의 계산시간 단축을 위한 방법을 분석한다.

• 한국정밀공학회지
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• 제17권10호
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• pp.147-154
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• 2000

A new hardware compensation method reducing displacement measurement errors, caused by tilt of index scale in moire linear encoders, has been developed. In conventional moire linear encoders, the detectors are aligned perpendicular to the line of moire fringes this structure is very sensitive to an unwanted tilt of the gratings. In this paper, a newly designed grating, called a phase-modulated grating, is developed to compensate for non-orthogonal errors. By using the phase-modulated grating instead of a conventional index, it is possible to reduce non-orthogonal errors of moire linear encoders.