• 한국환경과학회지
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• 제18권8호
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• pp.885-897
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• 2009

In order to make sure the impact of spatial resolution of wind energy map on the estimation of wind power density in the Korean Peninsula, the comparison studies on the characteristics of wind energy map with three different spatial resolutions were carried out. Numerical model used in the establishment of wind map is MM5 (5th generation Mesoscale Model) with RBAPS (Regional Data Assimilation and Prediction System) as initial and boundary data. Analyzed Period are four months (March, August, October, and December), which are representative of four seasons. Since high spatial resolution of wind map make the undulation of topography be clear, wind pattern in high resolution wind map is correspond well with topography pattern and maximum value of wind speed is also increase. Indication of island and mountains in wind energy map depends on the its spatial resolution, so wind patterns in Heuksan island and Jiri mountains are clearly different in high and low resolutions. And area averaged power density can be changed by estimation method of wind speed for unit area in the numerical model and by treatment of air density. Therefore the studiable resolution for the topography should be evaluated and set before the estimation of wind resources in the Korean Peninsula.

• 대기
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• 제21권4호
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• pp.391-404
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• 2011

This study investigates the impact of cumulus parameterization scheme (CPS) with different horizontal grid sizes on the simulation of the local heavy rainfall case over the Korean Peninsula. The Weather Research and Forecasting (WRF)-based real-time forecast system of the Joint Center for High-impact Weather and Climate Research (JHWC) is used. Three CPSs are used for sensitivity experiments: the BMJ (Betts-Miller-Janjic), GD (Grell-Devenyi ensemble), and KF (Kain-Fritsch) CPSs. The heavy rainfall case selected in this study is characterized by low-level jet and low-level transport of warm and moist air. In 27-km simulations (DM1), simulated precipitation is overestimated in the experiment with BMJ scheme, and it is underestimated with GD scheme. The experiment with KF scheme shows well-developed precipitation cells in the southern and the central region of the Korean Peninsula, which are similar to the observations. All schemes show wet bias and cold bias in the lower troposphere. The simulated rainfall in 27-km horizontal resolution has influence on rainfall forecast in 9-km horizontal resolution, so the statements on 27-km horizontal resolution can be applied to 9-km horizontal resolution. In the sensitivity experiments of CPS for DM3 (3-km resolution), the experiment with BMJ scheme shows better heavy rainfall forecast than the other experiments. The experiments with CPS in 3-km horizontal resolution improve rainfall forecasts compared to the experiments without CPS, especially in rainfall distribution. The experiments with CPS show lower LCL(Lifted Condensation Level) than those without CPS at the maximum rainfall point, and weaker vertical velocity is simulated in the experiments with CPS compared to the experiments without CPS. It means that CPS suppresses convective instability and influences mainly convective rainfall. Consequently, heavy rainfall simulation with BMJ CPS is better than the other CPSs, and even in 3-km horizontal resolution, CPS should be applied to control convective instability. This conclusion can be generalized by conducting more experiments for a variety of cases over the Korean Peninsula.

• Journal of Korean Neurosurgical Society
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• 제48권6호
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• pp.518-523
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• 2010

Objective : Chronic subdural hematoma (CSDH) is known to have a significant recurrence rate. There are different criteria defining the recurrence of CSDH. We evaluated the postoperative course of CSDH and tried to propose the reasonable criteria of recurrence. Methods : We retrospectively examined the medical records and pre- and postoperative CT scans of 149 consecutive patients who underwent surgery from January 2005 to December 2009. Diagnosis was confirmed by CT scanning or MRI. The postoperative courses were either resolved or recurrent. The resolved CSDH was one of the three types; early resolution, delayed resolution, or late resolution. The recurrent CSDH was one of the four types; recurrence without resolution, early recurrence after resolution, late recurrence after resolution, or recurrent-and-resolved type. Results : The CSDH was resolved within 30 days after surgery in 58 (39%) patients, between 1 to 3 months in 62 (42%), and after 3 months in 11 (7%) patients. The CSDH was recurred in 18 (12%) patients. Late resolution or recurrence was more common in the aged. The recurrent hematoma was seen on the same side in 11 patients, on the different side in 7 patients. Recurrence was significantly more common in the thick hematomas. Conclusion : For a working criteria of the recurrence of CSDH, we propose the early recurrence as return of symptoms or reaccumulation of the hematoma after a surgery within 3 months regardless of the location, amount or repeated operations. The late recurrence can be defined as reappearance or enlargement of a liquefied hematoma within the cranial cavity surrounded by the membranes or persistent CSDH beyond 3 months after surgery.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.463-466
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• 2009

The numerical simulation optimized by Four Dimensional Data Assimilation (FDDA) with Quick Scatterometer (QuikSCAT) data is carried out to evaluate wind resource characteristics at various heights in the southeastern area of the Korean Peninsula, where wind farms are planned to be built on on- and off-shore as well as comparable diurnal wind variations are characterized at the surface. The temporal and spatial distributions of modeled wind speeds showed good agreement with the observations based on the temporal variation analysis. Model results indicate that the higher model is performed in resolution, the more precise results is at turbine hub height. Occasionally, wind speed variations for each numerical resolution has a different regional and seasonal variations. In the coast area, hub height wind speed of 9km-resolution is simillar to that of 3km-resolution. On the other hand, hub height wind speed of 3km-resolution is simillar to that of 1km-resolution in the Jiri mountainous area.

• 대한원격탐사학회지
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• 제16권1호
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• pp.87-98
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• 2000

상업위성에서 공급되는 고해상도영상의 활용을 증대하기 위한 영상합성에 대한 관심이 증가하고 있다. 합성에 사용된 고해상도 흑백영상과 저해상도 다중분광영상은 항공기탑재 다중분광 주사기에 의해 촬영된 네 밴드의 영상을 이용하여 모의 제작하였다. 모의 합성된 2rl 해상도의 흑백 영상과 Bnl 해상도의 네 밴드 영상에 대하여 다섯 가지 합성방법(MWD, ItIS, PCA, HPF, CN, PCA) 을 적용하였다. 합성된 영상에 대해서 원래 영상들이 가지고 있던 공간해상도와 분광정보 측면의 특성을 분석하고자, 육안판독, 통계치비교, semivariogram, 분광반사특성 등을 비교하였다. MWD 변환방법에 의하여 합성된 영상이 공간해상도 및 분광정보 측면에서 모두 합성에 사용된 원래 영상과 근접한 결과를 보였다.

• 한국항행학회논문지
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• 제27권5호
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• pp.568-573
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• 2023

레이다의 주요 성능 규격 중 하나인 거리 분해능은 동일한 속도 및 각도의 두 표적을 거리 상으로 분해할 수 있는 성능과 관련된 지표이다. 일반적으로 레이다 성능 규격에 정의된 분해능은 실제 두 표적 분해 관점이 아닌 송신 펄스 폭으로 정의된다. 송신 펄스 폭 수치는 설계 측면의 성능 규격일 뿐, 두 표적을 분해할 수 있는 최소 거리를 의미하는 것이 아니다. 본 논문에서는 송신 펄스폭과 레이다 알고리즘을 동시에 고려하여 동일한 속도 및 각도 정보를 가지는 두 신호가 거리 차이로 분해되어 개별 추적개시로 이어질 수 있는 최소 거리차이에 대해 분석한다. 분해능 이외의 다른 외부 간섭을 배제하기 위해 비콘(Beacon) 신호를 활용한 루프랩 (Roof-lab) 환경에서 지상시험을 수행하였고, 탐지 단계에서는 신호처리 알고리즘에 의해 개별 탐지 성능이 결정되고, 추적 형성 단계에서는 데이터 연관을 통한 중복성 검사 알고리즘에 의해 분해 성능이 결정되는 것을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제10권6호
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• pp.578-581
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• 1989

Two enantiomers of various 2-hydroxy acid esters have been resolved as the 3,5-dinitrophenyl carbamates on chiral stationary phases (CSPs) derived from ${\alpha}-arylalkylamines.$ Two CSPs, each of which contains the same type of chiral moiety, but shows different mode of connection to a silica support, have been found to show the contrasting resolution behaviors. From the contrasting resolution behaviours of two CSPs used in this study, two competing chiral recognition mechanisms are proposed.

• Wind and Structures
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• 제6권6호
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• pp.419-436
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• 2003

Large-eddy simulations of the flow around a circular cylinder at a Reynolds number, based on cylinder diameter and free-stream velocity, $Re_D=2{\times}10^4$ are presented. Three different dynamic subgrid-scale models are used, viz. the dynamic eddy-viscosity model and two different mixed two-parameter models. The sensitivity to grid refinement in the spanwise and radial directions is systematically investigated. For the highest resolution considered, the effects of subgrid-scale modeling are also discussed in detail. In particular, it is shown that SGS modeling has a significant influence on the low-frequency modulations of the aerodynamics loads, which are related to significant changes in the near wake structure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1310-1315
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• 2003

In many practical engineering design problems, there are some design and manufacturing considerations that are difficult or infeasible to express in terms of an objective function or a constraint. In this situation, a set of optimal candidate designs having different topological complexities, not just a single optimal design, is preferred. To generate systematically such design candidates, we propose a hierarchical multiscale design resolution control scheme. In order to adjust its topological complexity by choosing a different starting resolution level in the hierarchical design space, we propose to employ a general M-band wavelet transform in transforming the original design space into the multiscale design space.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권3호
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• pp.578-597
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• 2014

Understanding of 'spatial' pressure distribution is required to determine design loads on local structures, such as plating and framing. However, obtaining a practical 'spatial' pressure distribution is a hard task due to the sensitivity of the data acquisition frequency and resolution. High-resolution Pessure-Idicating Flm (PIF) was applied to obtain pressure distribution and pressure magnitude using stepped crushing method. Different types of PIF were stacked at each test to creating a pressure distribution plot at specific time steps. Two different concepts of plotting 'spatial' pressure-area curve was introduced and evaluated. Diverse unit pixel size was chosen to investigate the effect of the resolution in data analysis. Activated area was not significantly affected by unit pixel size; however, total force was highly sensitive.