• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.734-738
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• 2012

A comprehensive vibration assessment program for the Advanced Power Reactor 1400 reactor vessel internals is established in accordance with the United States Nuclear Regulatory Commission Regulatory Guide 1.20 Revision 3. This paper is related to instruments and measurement locations based on the vibration and stress response analysis results at the inner barrel assembly top plate in the reactor. The analysis results of the inner barrel assembly top plate in the reactor show that the deterministic stress and deformation due to the reactor coolant pump induced pressure pulsations are larger than the random stress and deformation induced by the flow turbulence. The selection of the instruments and measurement locations at Inner barrel assembly top plate in the reactor is essential requirements and very important study process for the vibration and stress measurement program in comprehensive vibration assessment program for the Advanced Power Reactor 1400 reactor vessel internals.

• 한국소음진동공학회논문집
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• 제22권5호
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• pp.474-479
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• 2012

A comprehensive vibration assessment program for the advanced power reactor 1400(APR1400) reactor vessel internals is established in accordance with the united states nuclear regulatory commission regulatory guide 1.20 revision 3. This paper is related to instruments and measurement locations based on the vibration and stress response analysis results of the inner barrel assembly top plate in APR1400. The analysis results of the inner barrel assembly top plate in the reactor show that the deterministic stress and deformation due to the reactor coolant pump induced pressure pulsations are larger than the random stress and deformation induced by the flow turbulence. The selection of the instruments and measurement locations at inner barrel assembly top plate in the reactor is essential requirements and very important study process for the vibration and stress measurement program in comprehensive vibration assessment program for APR1400 reactor vessel internals.

• 소성∙가공
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• 제24권6호
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• pp.437-442
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• 2015

The development of polishing technology has enabled the production of injection molds with high quality surfaces and shapes. For products such as mobile phones which require high quality performance the use of plastic materials has many constraints such as shrinkage and deflection. The purpose of the current research is to use reverse engineering in order to find and analyze the data of a selected aspherical lens and then creating a process to design an improved lens. Additionally, the improved lenses are subject to molding analysis. In order to solve this problem, the lens construction program, Zemax, was used to analyze and optimize performance. In the case of optimization, the object was to eliminate spherical aberration and to find good MTF data. The result of the optimization data was similar to the MTF data found from a random lens. Specific resin and analysis conditions were selected and CAD modeling was done to enhance the injection molding analysis.

• 천문학회보
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• 제35권2호
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• pp.75.1-75.1
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• 2010

The nature and origin of the intergalactic magnetic field (IGMF) are an outstanding problem of cosmology, yet they are not well understood. Measuring Faraday rotation (RM) is one of a few promising methods to explore the IGMF. We have theoretically investigated RM using a model of the IGMF based on a MHD turbulence dynamo (Ryu et al. 2008; Cho et al. 2009). In the previous KAS meeting, we reported the results for the present-day local universe; for instance, the probability distribution function (PDF) of ${\mid}RM{\mid}$ follows the lognormal distribution, the root mean square (rms) value for filaments is ~1 rad m^{-2}, and the power spectrum peaks at ~1 h^{-1} Mpc scale. In this talk, we extend our study of RM; by stacking simulation data up to redshift z=5 and taking account of the redshift distribution of radio sources, we have reproduced an observable view of RM through filaments against background radio sources. Our findings are as follows. The inducement of RM is a random walk process, so that the rms of RM increases with increasing path length. The rms value of RM for filaments reaches several rad m^{-2}. The PDF still follows the lognormal distribution, and the power spectrum of RM peaks at less than degree scale. Our predictions of RM could be tested, for instance, with LOFAR, ASKAP, MEERKAT, and SKA.

• 한국세라믹학회지
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• 제46권6호
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• pp.685-688
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• 2009

Surface Texturing is very important process for high cell efficiency in crystalline silicon solar cell. Anisotropic texturing with an alkali etchant was known not to be able to produce uniform surface morphology in multi-crystalline silicon (mc-Si), because of its different etching rate with random crystal orientation. In order to reduce surface reflectance of mc-Si wafer, the general etching tendency was studied with HF/HN$O_3$/De-ionized Water acidic solution. And the surface structures of textured mc-Si in various HF/HN$O_3$ ratios were compared. The surface morphology and reflectance of textured silicon wafers were measured by FE-SEM and UVvisible spectrophotometer, respectively. We obtained average reflectance of $16{\sim}19$% for wavelength between 400 nm and 900 nm depending on different etching conditions.

• 전자공학회논문지C
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• 제35C권11호
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• pp.89-98
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• 1998

정적 시스템 모델링을 위해 RBF 신경회로망의 은닉 유니트를 자동으로 생성하는 ERAN을 제안한다. ERAN은 관측 데이터의 신규성을 기반으로 새로운 은닉 유니트를 할당하는 RAN의 성능을 개선한 것이다. ERAN의 학습 과정은 새로운 은닉 유니트의 생성과 네트웍 파라미터 학습을 포함한다. 네트웍은 초기에 0개의 은닉 유니트로 시작하여 세 가지의 은닉 유니트 생성 판별기준을 만족할 경우에만 새로운 은닉 유니트를 생성시킨다. 네트웍의 파라미터는 LMS 알고리즘을 이용하여 조정한다. 제안한 ERAN의 성능은 순차 학습 및 랜덤 학습을 갖는 비선형 정적 시스템 모델링 문제에 대하여 RAN의 결과와 성능을 비교한다. 두 실험에 대하여 ERAN은 RAN 보다 적은 은닉 유니트를 가지고 정확성이 더 우수한 RBF 신경회로망을 구현할 수 있음을 보인다.

• 전자공학회논문지
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• 제49권10호
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• pp.209-216
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• 2012

본 논문에서는 실시간 적외선 감시시스템을 위하여 표적 영상의 평균 밝기, 면적, 종횡비로 구성된 영상특징들을 이용한 새로운 추적 방법을 제시한다. 지상 표적의 영상특징들의 시간적 변화는 수학적으로 지수함수적 상관함수를 갖는 랜덤프로세서로 모델링할 수 있다. 기존의 추적 필터에서 사용되어져 온 표적의 운동을 표현하는 표적의 위치, 속도성분뿐만 아니라, 표적의 기하학적 영상특징들을 모두 포함하는 상태벡터의 이산시간 동역학방정식 및 측정방정식을 유도했다. 시뮬레이션 결과 기존의 표적 위치 및 속도정보만 이용한 경우보다 제안된 추적방법이 추적정확도가 월등히 높음을 알 수 있었다.

• 한국초등과학교육학회지:초등과학교육
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• 제32권2호
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• pp.185-197
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• 2013

The purpose of this study was to analyze the difference between eye movements according to science achievement of elementary school students in observation situation. Science achievement was based on the results of national achievement test conducted in 2012, a random sampling of classes. As an assessment tool to check observation test, two observation measure problems from TSPS (Test of Science Process Skill; developed in 1994) suitable for eye tracking system are adopted. The subjects of this study were twenty students of sixth grade who agreed to participate in the research. SMI (SensoMotoric Instruments)' iView $X^{TM}$ RED was used to collect eye movement data and Experiment 3.1 and BeGaze 3.1 program were used to plan and analyze experiment. As a result, eye movements in observation test varied greatly in fixation duration, frequency, saccade, saccade velocity and eye blink according to students' science achievement. Based on the result of eye movements analysis, heuristic search eye movement was discussed as an alternative to improve underachievers' science achievement.

• 한국지반공학회논문집
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• 제29권1호
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• pp.149-159
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• 2013

본고는 암석 코아에 함수비가 증가함에 따라 포아송비 거동형태를 구명하기 위하여 일축압축강도시험을 시행하였다. 현장에서 출토빈도가 높은 퇴적암, 화성암 및 변성암 시료 307개를 대상으로 포아송비의 함수거동을 관찰하였다. 포아송비는 암석의 역학적, 물리적 parameter와는 상관성이 전혀 표출되지 않는 독립적인 거동을 하고 있다. 포아송비의 함수거동은 감소, 증가 및 자유거동을 표출하고 있다. 감소거동을 나타내는 시료는 전체의 약 70%이상이며 이것은 포아송비의 함수거동 중 절대적으로 우세한 것이다. 포아송비는 독립거동을 하기 때문에 간접적인 방법으로는 추정이 불가능하다. 따라서 설계, 시공 및 감리과정에서 현장암에 대한 실험 결과를 적용하여야 할 것이다.

• Earthquakes and Structures
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• 제18권1호
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• pp.45-56
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• 2020

The application of critical excitation method with displacement-based objective function for multi degree of freedom (MDOF) systems is investigated. To this end, a new critical excitation method is developed to find the critical input motion of a MDOF system as a synthetic accelerogram. The upper bound of earthquake input energy per unit mass is considered as a new constraint for the problem, and its advantages are discussed. Considering this constraint, the critical excitation method is then used to generate synthetic accelerograms for MDOF models corresponding to three shear buildings of 10, 16, and 22 stories. In order to demonstrate the reliability of generated accelerograms to estimate dynamic response of the structures, three target ground motions with considerable level of energy contents are selected to represent "real critical excitation" of each model, and the method is used to re-generate these ground motions. Afterwards, linear dynamic analyses are conducted using these accelerograms along with the generated critical excitations, to investigate the key parameters of response including maximum displacement, maximum interstory drift, and maximum absolute acceleration of stories. The results show that the generated critical excitations can make an acceptable estimate of the structural behavior compared to the target ground motions. Therefore, the method can be reliably implemented to generate critical excitation of the structure when real one is not available.