• 한국지반공학회논문집
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• 제40권4호
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• pp.49-60
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• 2024

지표투과레이더(Ground Penetrating Radar, GPR)는 빠른 탐사 속도로 광범위한 지역의 정보를 획득할 수 있으나, 데이터 해석에는 전문적인 지식이 필요하다. 많은 연구에서 다양한 조건과 상황에서 GPR 신호 특성을 분석하기 위해 수치해석 기법을 도입해왔다. 보다 현실적인 수치 모델을 구성하기 위해서는 지반의 불균질한 특성을 고려해야 한다. 지반의 불균질한 특성으로 인해 클러터(Clutter)가 발생하며, 클러터는 송신된 신호가 목표가 아닌, 다른 물체에 의해 반사되어 수신되는 신호를 의미한다. Peplinski 재료 모델과 프랙탈 기법은 이러한 불균질한 특성을 모사할 수 있지만, 입력 매개변수에 대한 연구가 부족하다. 또한, 현장 데이터와 해석 데이터의 유사성을 정량적으로 평가할 수 있는 방법도 확립되지 않았다. 본 연구에서는 현장 데이터의 자기상관 계수를 계산하고 자기상관 함수를 통해 상관 거리를 산출하였다. 상관 거리는 데이터가 유사성을 보이는 시간적 혹은 공간적 거리를 의미한다. 현장 데이터의 상관 거리와 프랙탈 가중치를 적용한 해석 모델의 상관 거리를 비교하여 불균질 지반에 대한 수치해석 모델을 정량적으로 평가하였다. 본 연구를 통해 현장의 클러터 특성을 반영한 수치 모델링 기법을 제시하였다.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제22권4호
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• pp.261-282
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• 2019

The research related to testing pupils' achievement in the field of Measurement and Measure in initial teaching of geometry points to an insufficient adoption of the basic components of the length measurement concept among pupils. In order to discover the cause, we looked at the basic components on which the procedure of measuring length using a ruler is based, highlighted the possibilities of introducing the procedure in measuring length, and determined pupils' achievement during the procedure of measuring length using a ruler. The research sample consisted of 145 pupils, out of which 72 were the 2^nd grade pupils and 73 were the 4^th grade pupils. A descriptive method was applied in the research. The technique we used was testing, and for the statistical data processing we used a χ² test. The results of the research show that, when drawing a straight line of a given length using a ruler, there is no statistical difference in achievement between the 2^nd and 4^th grade pupils, nor in the pupils' knowledge regarding drawing a ruler independently, while drawing a straight line of a given length using a "broken" ruler 4^th grade pupils are statistically better. The results of the research indicate that pupils' achievement is better in doing standard tasks than in non-standard ones, given that the latter require conceptual knowledge. The components of the concept of length measurement using ruler have not been sufficiently developed yet, and these include: zero-point, partitioning a measured object in a series of consecutive measurement units and their iteration. We shed more light on the critical stage in the procedure of length measurement - the transition from non-standard to standard units and the formation of the length measurement scale. For further research, we propose to look at the formation of the concept of length measurement using the ruler through all its components and their inclusion in the mathematics curriculum, as well as examining the correlation of pupils' achievement in the procedure of measuring length with their achievement in measuring area (and volume).

• 한국음향학회지
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• 제41권3호
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• pp.319-325
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• 2022

화자 인증 시스템에서 입력 발성 길이의 변화는 성능을 하락시킬 수 있는 대표적인 요인이다. 이러한 문제점을 개선하기 위해, 몇몇 연구에서는 시스템 내부의 특징 가공 과정을 여러가지 서로 다른 경로에서 수행하거나 서로 다른 수용 영역(Receptive Field)을 가진 합성곱 계층을 활용하여 다양한 화자 특징을 추출하였다. 이러한 연구에 착안하여, 본 연구에서는 가변 길이 입력 발성을 처리하기 위해 보다 다양한 수용 영역에서 화자 정보를 추출하고 이를 선택적으로 통합하는 통합된 수용 영역 다양화 기법을 제안한다. 제안한 통합 기법은 입력된 특징을 여러가지 서로 다른 경로에서 다른 수용 영역을 가진 합성곱 계층으로 가공하며, 가공된 특징을 입력 발성의 길이에 따라 동적으로 통합하여 화자 특징을 추출한다. 본 연구의 심층신경망은 VoxCeleb2 데이터세트로 학습되었으며, 가변 길이 입력 발성에 대한 성능을 확인하기 위해 VoxCeleb1 평가 데이터 세트를 1 s, 2 s, 5 s 길이로 자른 발성과 전체 길이 발성에 대해 각각 평가를 수행하였다. 실험 결과, 통합된 수용 영역 다양화 기법이 베이스라인 대비 동일 오류율을 평균적으로 19.7 % 감소시켜, 제안한 기법이 가변 길이 입력 발성에 의한 성능 저하를 개선할 수 있음을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1277-1281
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• 2007

A Nano-tip as a cold field emitter for inducing a field emission current has manufactured in many ways. In the paper, the electrochemical etching method is used. Thus, in order to optimize the final shape as the field emitter, the reliable fabrication system for electrochemical etching was constructed. In addition, the effective parameters such as applied voltage, submerged length, meniscus height, electrolyte concentration and environmental condition(vibration, humidity, cut-off time) have investigated in detail. By controlling the parameters, reliable tungsten tip for field emitter was fabricated. And the fabricated tungsten tip was evaluated optically. Finally, the very sharp apex of the tungsten tip was observed with scanning electron microscope.

• 천문학회지
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• 제29권spc1호
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• pp.397-398
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• 1996

Large field spectrographs are severely influenced by atmospheric refraction. LAMOST is a large field multi-object spectroscopy telescope with $5^{\circ}$ field of view, f/5 focus ratio and 20m focal length. There will be 4000 fibers simultaneous on it's $\phi$1.75m focal plane. Here we discuss the atmospheric refraction effects on LAMOST in two hands. One is the effect of differential refraction across the field, another is the effect of atmospheric dispersion. According to the calculation, we find that: 1. The largest deviation from center within the field is 4.;32" during a 1.5-hour integration at $80^{\circ}$ declination. 2. The directions of deviation are complex, so the deviations can't be decreased by rotating the field. We also give out the atmospheric dispersions.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.478-479
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• 2008

this paper describes the electric field distribution interpretation along a shield form inner vacuum interrupter(VI). The equipotential line and electric field and field vector in a VI are analysed by a finite element method at various shield form. in result, The equipotential line and electric field distribution was affected to VI shield form. The reason is as it gets distortion of equipotential line done. shield of cup type is how to electric field distribution, finally, this paper recognized whether or not affected, and proposed gap with the most suitable shield length and an external insulation.

• Journal of Magnetics
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• 제15권4호
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• pp.221-224
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• 2010

A laboratory sensor model was designed, constructed, and tested based on a newly proposed working principle of magnetic field detection. The principle of sensing employed a time-coded method in correlation with exploiting the advantageous features of the GMI effect. The sensor demonstrated a sensitivity of $10\;{\mu}s/{\mu}T$ in the field range of ${\pm}100\;{\mu}T$. The sensing element in the form of an amorphous thin wire, $100\;{\mu}m$ in diameter ${\times}50\;mm$ long, was fit into a small field modulation coil of 60 mm length. At a magnetic field modulation in the range of hundreds of Hz, the change in time interval of two adjacent GMI voltage peaks was linearly related to the external magnetic field to be measured. This mechanism improved the sensor linearity of the GMI sensor to better than 0.2% in the measuring range of ${\pm}100\;{\mu}T$.

• Journal of Magnetics
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• 제14권3호
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• pp.129-131
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• 2009

A time-coded giant magnetoimpedance (GMI) magnetic field sensor was investigated and designed. The successfully constructed and tested laboratory model demonstrated a sensitivity of 5 ${\mu}s/{\mu}T$ in the field range of $\pm200{\mu}T$. The sensing element in the form of an amorphous thin wire, 100 mm in diameter $\times50$ mm long, was fit into a small field modulation coil of 60 mm length. At a magnetic field modulation in the range of hundreds of Hz, the change in time interval of two adjacent GMI voltage peaks was linearly related to the external magnetic field to be measured. This mechanism improved the sensor linearity to better than 0.3% in the measuring range of $\pm200{\mu}T$.

• JSTS:Journal of Semiconductor Technology and Science
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• 제10권4호
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• pp.265-275
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• 2010

In this work, reliable methodology for device design is presented. Based on this method, the underlap length has been optimized for minimizing the gateinduced drain leakage (GIDL) in a 22-nm node 4-terminal (4-T) silicon-on-insulator (SOI) fin-shaped field effect transistor (FinFET) by TCAD simulation. In order to examine the effects of underlap length on GIDL more realistically, doping profile of the source and drain (S/D) junctions, carrier lifetimes, and the parameters for a band-to-band tunneling (BTBT) model have been experimentally extracted from the devices of 90-nm channel length as well as pnjunction test element groups (TEGs). It was confirmed that the underlap length should be near 15 nm to suppress GIDL effectively for reliable low standby power (LSTP) operation.

• Asian Journal of Atmospheric Environment
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• 제12권1호
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• pp.47-58
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• 2018

The aim of this work is to investigate the effect of atmospheric stability on near-field pollutant dispersion from rooftop emissions of a single cubic building using computational fluid dynamics (CFD). This paper used the shear stress transport (here after SST) k-${\omega}$ model for predicting the flow and pollutant dispersion around an isolated cubic building. CFD simulations were performed with two emission rates and six atmospheric stability conditions. The results of the simulations were compared with the data from wind tunnel experiments and the result of simulations obtained by previous studies in neutral atmospheric condition. The results indicate that the reattachment length on the roof ($X_R$) obtained by computations show good agreement with the experimental results. However, the reattachment length of the rooftop of the building ($X_F$) is greatly overestimated compared to the findings of wind tunnel test. The result also shows that the general distribution of dimensionless concentration given by SST k-${\omega}$ at the side and leeward wall surfaces is similar to that of the experiment. In unstable conditions, the length of the rooftop cavity was decreased. In stable conditions, the horizontal velocity in the lower part around the building was increased and the vertical velocity around the building was decreased. Stratification increased the horizontal cavity length and width near surface and unstable stratification decreased the horizontal cavity length and width near surface. Maintained stability increases the lateral spread of the plume on the leeward surface. The concentration levels close to the ground's surface under stable conditions were higher than under unstable and neutral conditions.