• 한국과학교육학회지
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• 제13권2호
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• pp.135-145
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• 1993

This study investigated student's prior conceptions and evidence evaluation about Light and shadow. One hundred twenty six students were given Explanation-after-choice type Questions to investigate student' prior conceptions and Choicd type Question to identify student's idea about scientific method and characteristics od observation. Forty-four of the 126 students were interviewed to explore student's evidence evaluation. Eighty students (63.5%) thought that the shape of material affected the shape of shadow but the shape of light source did not Only 58.8 precents of all responses were evidence-based responses. Characteristics of evidence affected student's evidence evaluation : student made evidence-based responsed to the accord evidence more frequently than discord evidence. Among evidence-based response to the discord evidence. 35.5% of responses were the case that student felt cognitive conflict or explored other variables by recognizing discord between his/her own ideas and evidence or distort the evidence. Student's idea about characteristics of observation did not affect the evidence evaluation, but student's idea about scientific method affected the evidence evaluation.

• 한국측량학회지
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• 제37권5호
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• pp.331-341
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• 2019

With the popularity of sensor-rich environments, smartphones have become one of the major platforms for obtaining and sharing information. Since it is difficult to utilize GNSS (Global Navigation Satellite System) inside the area with many buildings, the localization of smartphone in this case is considered as a challenging task. To resolve problem of localization using smartphone a four step image-based localization method and procedure is proposed. To improve the localization accuracy of smartphone datasets, MMS (Mobile Mapping System) and Google Street View were utilized. In our approach first, the searching for candidate matching image is performed by the query image of smartphone's using GNSS observation. Second, the SURF (Speed-Up Robust Features) image matching between the smartphone image and reference dataset is done and the wrong matching points are eliminated. Third, the geometric transformation is performed using the matching points with 2D affine transformation. Finally, the smartphone location and attitude estimation are done by PnP (Perspective-n-Point) algorithm. The location of smartphone GNSS observation is improved from the original 10.204m to a mean error of 3.575m. The attitude estimation is lower than 25 degrees from the 92.4% of the adjsuted images with an average of 5.1973 degrees.

• Advances in aircraft and spacecraft science
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• 제9권5호
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• pp.449-462
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• 2022

Space-telescopes placed in the Sun-Earth second Lagrange point (L2) observe the sky following a scan strategy that is usually based on a spin-precession motion. Knowing which regions of the sky will be more observed by the instrument is important for the science operations and the instrument calibration. Computing sky observation parameters numerically (discretizing time and the sky) can consume large amounts of time and computational resources, especially when high resolution isrequired.This problem becomesmore critical if quantities are evaluated at detector level instead of considering the instrument entire Field of View (FoV). In previous studies, the authors have derived analytic solutions for quantities that characterize the observation of each point in the sky in terms of observation time according to the scan strategy parameters and the instrument FoV. Analytic solutions allow to obtain results faster than using numerical methods as well as capture detailed characteristics which can be overseen due to discretization limitations. The original approach is based on the analytic expression of the instrument trace over the sky. Such equations are implicit and thusrequiresthe use of numeric solversto compute the quantities.In this work, a new and simpler approach for computing one ofsuch quantities(mean observation time) is presented.The quantity is first computed for pure spin motion and then the effect of the spin axis precession is incorporated under the assumption that the precession motion is slow compared to the spin motion.In this sense, this new approach further simplifies the analytic approach, sparing the use of numeric solvers, which reduces the complexity of the implementation and the computing time.

• 한국지반공학회지:지반
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• 제13권6호
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• pp.5-12
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• 1997

연약지반 개량을 위한 프리로딩 공법에서 침하 애측은 시공관리상 매우 중요한 요소이다. 지반의 비균질성, 지반 물성치 조사의 한계 등의 이유로 설계시에 침하속도 및 침하량을 실제 발생치와 근접하게 예측하기는 매우 어렵다. 이러한 문제점 때문에 쌍곡선법,아사오카법 등 초기 침하계측을 이용한 장래 침하 추정 법들이 침하 예측 기법으로 활발하게 이용되고 있으나, 예측 시점에서 추정된 장래 침하량의 신뢰성에 대한 평가 방법엔 대하여서는 제시된 바가 없다. 본 연구는 사례연구를 통하여 쌍곡선법으로 예측된 장래침하량들과 실 침하량들을 비교하구 초기 계측 기간에 따른 장래 침하량 예측의 신뢰성에 관한 분석을 통하여. 쌍곡선법을 이용한 장래 침하량 추정의 신뢰성 평가 방법을 제시하고자 한다.

• 전기학회논문지
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• 제56권4호
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• pp.724-729
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• 2007

In this paper, we propose a new diagnosis method of DC/DC converter aging. The method is based on variations of the parasitic resistor for the aging process. We apply an on-line diagnosis of the DC/DC converter because the observation is not a device, but a system. This study proposes a method of DC/DC converter diagnosis by analyzing the variations of model on the variations of parasitic resistor.

• 한국전자파학회논문지
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• 제25권6호
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• pp.700-708
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• 2014

제트엔진 변조(Jet Engine Modulation: JEM)는 회전하는 제트엔진 터빈으로부터의 전자기 산란에 따른 레이더 신호의 주파수 변조 현상이다. JEM은 표적의 고유한 정보를 제공하여 대표적인 레이더 표적 인식 수단으로 활용되나, JEM 성분이 미약하게 존재하는 레이더 관측 범위에서는 JEM에 의한 레이더 표적 인식 성능이 저하될 수 있다. 이에 본 논문에서는 복소 신호의 경험적인 모드분리법(Complex Empirical Mode Decomposition: CEMD)를 이용하여 레이더 신호를 여러 기본성분인 고유 모드 함수(Intrinsic Mode Function: IMF)로 분리하고, 신호의 이심률을 기반으로 이들 IMF를 조합하는 근거를 제공하여 JEM 성분을 추출하는 기법을 제시한다. 다양한 신호에 대한 적용 결과를 통하여 제안된 기법이 JEM의 명확성을 개선하는 한편, JEM 해석의 유효 관측 범위를 확장시킬 수 있음을 입증하였다.

• Computers and Concrete
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• 제7권1호
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• pp.63-81
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• 2010

We present the shape determination method of 3-D reinforcement corrosion based on observed temperature on concrete surface. The non-destructive testing for reinforcement corrosion in concrete using a heat image on concrete surface have been proposed by Oshita. The position of the reinforcement of corrosion or the cavity can be found using that method. However, the size of those defects can not be precisely measured based on the heat image. We therefore proposed the numerical determination system of the shape for the reinforcement corrosion using the observed temperature on the concrete surface. The adjoint variable method is introduced to formulate the shape determination problem, and the finite element method is employed to simulate the heat transfer problem. Some numerical experiments and the examination for the number of the observation points are shown in this paper.

• 천문학회보
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• 제39권2호
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• pp.110.1-110.1
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• 2014

The optics of Space telescope is one of the major parts of space mission used for imaging observation of astronomical targets and the Earth. These kinds of space mission have a bulky and complex opto-mechanics with a long optical tube, but there are attempts have been made to observe a target with a small satellite in many ways. In this paper, we describe an optical design of a reflecting telescope for use in a CubeSat mission. For this design, we adopt the off-axis segmented method of astronomical observation techniques based on the Ritchey-Chr$\acute{e}$tien type telescope. The primary mirror shape is a rectangle with dimensions of $8cm{\times}8cm$, and a secondary mirror has dimensions of $2.4cm{\times}4.1cm$. The focal ratio is 3 which can obtain a $0.3{\times}0.2$ degree diagonal angle in a $1280{\times}800$ CMOS color image sensor with a pixel size of $3{\mu}m{\times}3{\mu}m$. This optical design can capture a ${\sim}4km{\times}{\sim}2.3km$ area of the earth's surface at 700 km altitude operation. Based on this conceptual design, we will keep trying to study more for astronomical observation with Attitude control system.

• 한국안전학회지
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• 제20권3호
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• pp.19-26
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• 2005

There are three reasoning method in fault diagnosis process. The shallow reasoning is based on the experiential knowledge and deep reasoning is based on physical model. Hybrid reasoning is mixing two type reasoning. This study describes about fault train embodiment of screw type air compressor that is used widely in industrial facilities by using various experimental method and shallow reasoning. We investigate macroscopic failure cause of air compressor through naked eye observation and then microscopic failure cause by various experimental method. We composed fault train with fault knowledge based on empirical data and scientific data that is acquired through several experiments. It is possible to analysis system reliability and failure rate with these fault train.

• 대한음성학회지:말소리
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• 제64호
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• pp.121-135
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• 2007

Speech signal is distorted by channel characteristics or additive noise and then the performances of speaker or speech recognition are severely degraded. To cope with the noise problem, we propose a modified HMM decoder algorithm using SNR-based observation confidence, which was successfully applied for GMM in speaker identification task. The modification is done by weighting observation probabilities with reliability values obtained from SNR. Also, we apply PSO (particle swarm optimization) method to the confidence function for maximizing the speaker identification performance. To evaluate our proposed method, we used the ETRI database for speaker recognition. The experimental results showed that the performance was definitely enhanced with the modified HMM decoder algorithm.