• 대한원격탐사학회지
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• 제33권1호
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• pp.25-35
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• 2017

Spatial downscaling with fine resolution auxiliary variables has been widely applied to predict precipitation at fine resolution from coarse resolution satellite-based precipitation products. The spatial downscaling framework is usually based on the decomposition of precipitation values into trend and residual components. The fine resolution auxiliary variables contribute to the estimation of the trend components. The main focus of this study is on quantitative analysis of impacts of trend component estimates on predictive performance in spatial downscaling. Two regression models were considered to estimate the trend components: multiple linear regression (MLR) and geographically weighted regression (GWR). After estimating the trend components using the two models,residual components were predicted at fine resolution grids using area-to-point kriging. Finally, the sum of the trend and residual components were considered as downscaling results. From the downscaling experiments with time-series Tropical Rainfall Measuring Mission (TRMM) 3B43 precipitation data, MLR-based downscaling showed the similar or even better predictive performance, compared with GWR-based downscaling with very high explanatory power. Despite very high explanatory power of GWR, the relationships quantified from TRMM precipitation data with errors and the auxiliary variables at coarse resolution may exaggerate the errors in the trend components at fine resolution. As a result, the errors attached to the trend estimates greatly affected the predictive performance. These results indicate that any regression model with high explanatory power does not always improve predictive performance due to intrinsic errors of the input coarse resolution data. Thus, it is suggested that the explanatory power of trend estimation models alone cannot be always used for the selection of an optimal model in spatial downscaling with fine resolution auxiliary variables.

• 한국환경과학회지
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• 제4권2호
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• pp.159-168
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• 1995

To predict reasonably the movement and the concentration of the pollutants in the coastal area. A simulation model should be prepared considering detail topography with land-sea and the urban effects, and the resolution near the source. The explicit method can not be applied due to the instability of the numerical calculation in high horizontal-grid resolution, while the ADI scheme satisfied with the high horizontal grid resolution and can be used in the fine mesh system which shows the detail topography, atmospheric flow The ADI method which studied the high horizontal grid resolution was excellent. The two dimensional model used in the study using ADI method is proved as a reasonable model to predict the wind field in any small scale area including mountainous coastal urban area.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.807-810
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• 2000

In this paper, a new hierarchical motion estimation (ME) scheme using the wavelet transformed multi-resolution image layers is proposed. While the coarse-to-fine (CtF) ME, used in previously proposed coding schemes, can provide a better estimate at the coarsest resolution, it is difficult to accurately track motion at finer resolution. On the other hand, in fine-to-coarse (FtC) ME, it can solves this local minima problem by estimating motion track at the finest subband and propagating the motion vector (MV) to coarser subband. But this method causes to higher computational overhead. This paper proposes a new method for reducing the computational overhead of fine-to-coarse rnulti-resolution motion estimation (MRME) at the finest resolution level by searching for the region to consider motion vectors of the coarsest resolution subband.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 추계학술대회 논문집
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• pp.545-546
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• 2007

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.123-128
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• 2005

A novel tri-mode ultraprecision positioning system for machine tools and measuring machine is proposed. The basic coarse mode uses a Twist-roller Friction Drive (abbr. TFD), and controls several tens of millimeters of the machine-table travel with nanometer order of positioning resolution. The fine mode also utilizes the TFD with a fine adjusting mechanism. The resolution of the fine mode is in the range of sub-nanometer. For realizing picometer positioning, the ultra-fine mode is executed by using an active aerostatic guideway. On the bearing surface of this active guideway, several Active Inherent Restrictors (abbr. AIRs) are embedded for controlling the table position. An AIR unit consists of a piezoelectric actuator having a through hole, one end of the hole on the bearing surface acts as an inherent restrictor. Owing to the aerostatic mechanism of the AIR, the deformation of the piezoelectric actuator in the AIR unit causes much reduced table displacement. Such motion reduction is effective for ultraprecision positioning. Current positioning resolution of the ultra-fine mode is 50pm, however the final goal of the positioning resolution is expected to be in the order of picometer.

• 한국항공우주학회지
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• 제34권8호
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• pp.104-108
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• 2006

항공기나 위성에 탑재되어 지표면의 영상을 획득하기 위한 합성 개구 레이더의 영상 분해능은 거리 방향 분해능(Range Resolution)과 이에 수직한 방향의 분해능(Azimuth Resolution)으로 구분할 수 있다. 레이더 센서를 이용한 영상의 해상도를 향상시키기 위해서는 신호처리를 위한 첩 펄스를 광대역화 할 필요가 있으며, 본 논문에서는 고해상도의 영상을 획득 할 수 있는 디지털 첩 펄스 발생기를 설계하였다. 디지털 첩 펄스 발생기는 크게 AWG방식과 DDS방식으로 구분할 수 있으며 본 연구에서는 DDS방식의 첩 펄스 발생기로 선형 주파수 변조(LFM) 파를 발생시키는 300MHz 대역의 광대역 디지털 첩 펄스 발생기를 개발하였다. 개발된 첩 펄스 발생기는 거리 방향 분해능이 50cm 이상 되는 고해상도 영상 레이더 시스템을 구현할 수 있는 성능을 가진다.

• 전기전자학회논문지
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• 제6권1호
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• pp.21-29
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• 2002

본 논문에서는 전부 디지털 회로로 구성된 고 해상도의 DLL(Delay Locked Loop)를 제안하였다. 제안된 회로는 위상 검출기, 지연 선택 블록, 그리고 각각의 지연 체인을 가지는 Coarse, Fine 그리고 Ultra Fine 위상조정 블록의 삼 단의 형식으로 되어 있다. 첫 번째 단은 Ultra Fine 위상조정블록으로 고 해상도를 얻기 위하여 Vernier Delay Line을 사용하였다. 두 번째와 세 번째 단은 Coarse와 Fine 위상조정블록으로 각각의 단위 지연 체인을 이루는 단위 지연 소자의 해상도 만큼의 위상 제어를 하게 되며, 두 단은 상당히 비슷한 구조를 이루고 있다. 회로는 HSPICE를 이용하여 공급 전압이 3.3V인 $0.35{\mu}m$ CMOS 공정으로 시뮬레이션 되었다. 시뮬레이션 결과 회로의 해상도를 약 10ps로 높일 수 있었으며, 동작 범위는 250MHz에서 800MHz 이다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.587-588
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• 2006

Drop-on-Demand (DOD) inkjet printing technology, especially piezo-typed, has been paid attention by industries due to its inherent nature of unbeatable material usage and low cost manufacturing cost. Despite of these key advantages over any other competing manufacturing technologies, the primary disadvantage has been considered as its limited capability to produce fine resolution patterns with a commercially available DOD inkjet print head. Although the main effort has been focused on the production of a DOD inkjet print head with smaller nozzles to overcome this challenging issue, an alternative approach could be taken and it would enable to expand the employment of DOD inkjet printing technology to applications requiring fine patterns further more.

• Macromolecular Research
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• 제12권4호
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• pp.391-398
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• 2004

Thick-film photolithography is a new technology that combines lithography processes, such as exposure and development, with the conventional thick-film process applied to screen-printing. In this study, we developed a low-temperature cofireable silver paste applicable for thick-film processing to form fine lines using photolitho-graphic technologies. The optimum paste composition for forming fine lines was investigated. The effect of processing parameters, such as the exposing dose, had on the fine-line resolution was also investigated. As the result, we found that the type of polymer and monomer, the silver powder loading, and the amount of photoinitiator were the main factors affecting the resolution of the fine lines. The developed photoimageable silver paste was printed on a low-temperature cofireable green sheet, dried, exposed, developed in an aqueous process, laminated, and then fired. Our results demonstrate that thick-film fine lines having widths < 20 $\mu\textrm{m}$ can be obtained after cofiring.

• 한국환경과학회지
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• 제4권5호
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• pp.403-411
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• 1995

The atmospheric responses to a Sea Surface Temperature Anomaly(SSTA) over the equatorial eastern Pacific Ocean have been investigated using the horizontally fine resolution model based on OSU 2-layer Atmospheric General Circulation Model(AGCM). The SSTAS daring the peak phase of 1982-83 El Nino have been applied to the model as the boundary conditions of the experiment. The model simulates the eastward movement of the rising branch of the Walker circulation. That is, the major features associated with the El Nino such as the increase of the precipitation rate over the center of the Pacific and decrease over the Indonesia, and the 500hPa geopotential height anomaly in the middle latitude are properly describes in the fine resolution model experiment. The model results indicate that this horizontally fine resolution UM can successfully simulate the ENSO anomalies and be more effectivelly used for the study of the climate and the climate changes.