PDSI와 범지구적 해수면온도와의 저빈도 상관성 분석

오태석,김성실,문영일 한국방재학회 2010 한국방재학회논문집 Vol.10 No.3

가뭄은 인간이 극복하기 힘든 자연재해로서 가뭄지역의 경제를 어렵게 할 뿐 아니라 생태계까지 파괴하기 때문에 전 세계적으로 가장 두려워하는 관심 재해 중 하나이다. 따라서 본 연구에서는 대표적인 가뭄지수인 팔머가뭄지수와 범지구적 해수면 온도의 상관관계를 분석하였다. 먼저 팔머가뭄지수를 산정하여 과거 가뭄발생연도와 비교분석을 실시하였다. 비교분석을 결과 대부분의 과거 가뭄사상과 지수가 일치하는 것으로 분석되었다. 상관성 분석을 위해 팔머가뭄지수 산정을 위한 지수인 강수자료와 온도자료를 월평균강수량과 월평균온도 자료로 산정하여 군집분석을 실시하였다. 우리나라 기상청관할에 있는 61개 지점을 선정하여 월평균강우량과 월평균온도 자료로 군집분석결과 총 6개의 군집을 형성하는 것으로 분석되었다. 또한, 군집분석결과와 팔머가뭄지수의 주성분 분석을 실시하였다. 주성분 분석을 통해 전체 자료의 분산을 80% 이상 설명할 수 있는 14개의 시계열자료를 추출하였다. 추출된 팔머가뭄지수의 주요 성분과 범지구적 해수면 온도와의 상관성 분석결과 팔머가뭄지수는 양의 상관관계가 음의 상관관계보다 큰 것으로 분석되었으며, 태평양에서 관측되는 해수면 온도와 통계적으로 유의한 상관관계를 갖는 해수면 온도 구역을 확인할 수 있었다. 이를 통해 해수면 온도를 이용하여 우리나라에 발생할 수 있는 가뭄의 예측 가능성을 제시하였다 Drought is one of disaster causing factors to produce severe damage in the World because drought is destroyed to the ecosystem as well as to make difficult the economy of the drought area. This study, using Palmer Drought Severity Index carries out correlation analysis with sea surface temperatures. Comparative analysis carries out by calculated Palmer Drought Severity Index and past drought occurrence year. Result of comparative analysis, PDSI indexes were in accord with the past drought. Cluster analysis for correlation analysis carries out using precipitation and temperature that is input datas palmer drought severity index, and the result of cluster analysis was classified as 6. Also, principal component carries out using result of cluster analysis. 14 principal component analyze out through principal component analysis. Using analyzed 14 principal component carries out correlation analysis with sea surface temperature that is delay time from 0month until 11month. Correlation analysis carries out sea surface temperatures and calculated cycle component of the low frequency through Wavelet Transform analysis form principal component. Result of correlation analysis, yang(+) correlation is bigger than yin(-) correlation. It is possible to check similar correlation statistically the area of sea surface temperature with sea surface temperature in the Pacific. Forecasting possibility of the future drought make propose using sea surface temperature.

도로 표면 강우 유출 해석 알고리즘 개발

조준범(Jun Beom Jo),김정수(Jung Soo Kim),곽창재(Chang Jae Kwak) 응용생태공학회 2021 Ecology and resilient infrastructure Vol.8 No.4

일반적으로 도심지에서의 유출은 도로 노면을 따라 유출되어 빗물받이를 통해 우수관거로 배수된다. 따라서 적절한 도로 배수능력의 평가는 도로와 빗물받이 뿐만 아니라 우수관거의 설계에서도 필수적이다. 하지만 도시 도로부의 지형학적 및 수리학적 조건을 반영한 흐름해석 방안에 대한 명확한 기준이 제시되어 있지 못한 실정이다. 그러므로 기존에 적용되던 흐름해석모형(등류/ 부등류) 및 도달시간 산정방법 (임계/고정)을 분석하여 최적의 도로의 흐름해석 방안이 제시되어야 한다. 본 연구에서는 도로 표면 흐름해석을 위한 알고리즘을 개발하고 등류와 부등류 흐름해석 모형 및 도달시간 산정방법을 매개변수로 적용한 수치적 분석을 수행하여 다양한 도로조건에서의 강우 유출특성을 모의하였다. 도로조건은 국내의 설계기준을 고려하여 2차선 도로의 폭 (6 m)과 경사 (도로 종경사 1 - 10%, 도로 노면경사 2% 및 측구 횡경사 2 - 10%)가 고려되었다. 또한, 도로 표면의 흐름은 노면경사를 따라 측구에서 차집되어 하류부의 빗물받이를 통해 배수되도록 하였으며, 측구의 폭은 0.5 m로 선정하였다. 모의 결과 도로의 유출특성은 도로 경사 조건에 따라 민감하게 변화하였으며, 부등류 해석모형이 도로의 하류부로 강우가 차집되며 변화하는 측구부에서의 유출특성을 반영하여 등류 흐름해석 모형에 비해 최대 23.66%, 평균 11.80% 긴 도달시간과 최대 9.50%, 평균 4.73% 작은 도로 표면 총 유출량을 나타냈다. 따라서, 우수 유출량을 산정하기 위하여 도달시간을 강우의 지속시간으로 반영하는 임계지속시간을 적용한 부등류 흐름해석을 수행하는 것이 적합하다고 판단되었다. 개발된 알고리즘은 다양한 흐름해석 기법을 통합하여 도로 노면에서의 유출특성을 정밀하게 모의하고 있으므로 도로의 배수 설계에 활용이 가능할 것으로 기대된다. In general, stormwater flows to the road surface, especially in urban areas, and it is discharged through the drainage grate inlets on roads. The appropriate evaluation of the road drainage capacity is essential not only in the design of roads and inlets but also in the design of sewer systems. However, the method of road surface flow analysis that reflects he topographical and hydraulic conditions might not be fully developed. Therefore, the enhanced method of road surface flow analysis should be presented by investigating the existing analysis method such as the flow analysis module (uniform; varied) and the flow travel time (critical; fixed). In this study, the algorithm based on varied and uniform flow analysis was developed to analyze the flow pattern of road surface. The numerical analysis applied the uniform and varied flow analysis module and travel time as parameters were conducted to estimate the characteristics of rainfall-runoff in various road conditions using the developed algorithm. The width of the road (two-lane (6 m)) and the slope of the road (longitudinal slope of road 1 - 10%, transverse slope of road 2%, and transverse slope of gutter 2 - 10%) was considered. In addition, the flow of the road surface is collected from the gutter along the road slope and drained through the gutter in the downstream part, and the width of the gutter was selected to be 0.5 m. The simulation results were revealed that the runoff characteristics were affected by the road slope conditions, and it was found that the varied flow analysis module adequately reflected the gutter flow which is changed along the downstream caused by collecting of road surface flow at the gutter. The varied flow analysis module simulated 11.80% longer flow travel time on average (max. 23.66%) and 4.73% larger total road surface discharge on average (max. 9.50%) than the uniform flow analysis module. In order to accurately estimate the amount of runoff from the road, it was appropriate to perform flow analysis by applying the critical duration and the varied flow analysis module. The developed algorithm was expected to be able to be used in the design of road drainage because it was accurately simulated the runoff characteristics on the road surface.

Microrough titanium surface affects biologic response in MG63 osteoblast-like cells

Kim, Myung-Joo,Kim, Chang-Whe,Lim, Young-Jun,Heo, Seong-Joo Wiley Publishers 2006 Journal of Biomedical Materials Research Part A Vol. No.

<P>The purpose of this study was to define the surface properties of prepared titanium (Ti) disks, which served as a model system, and to contrast the biologic response of MG63 cells exposed to Ti disks with different levels of surface roughness. The surface properties interact with each other, resulting in a change of other surface qualities in addition to roughness due to the surface roughening procedure. The machined Ti disks were roughened by sandblasting and electric glow discharging. The surface properties of the Ti specimens were inspected through a comprehensive surface analysis. MG63 cell behaviors were compared along with cell number, alkaline phosphatase (ALP) activity, Runx2 gene expression, and type I collagen production. Statistics were evaluated, using analysis of variance (ANOVA). The sandblasted Ti disks demonstrated well-controlled surface roughness features and meaningful average roughness ranges, including the surface roughness of the “modern” microrough implant, used clinically. With increasing Ti surface roughness, the cell number decreased, while the ALP activity, type I collagen production, and Runx2 gene expression increased significantly. The rougher the Ti surface was, the sooner the Runx2 gene was expressed. Based on these results, we suggest that the microrough Ti surfaces of the 1–3 μm range may contribute effectively to osteogenic differentiation and proliferation in MG63 cells. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006</P>

Three-dimensional fuzzy influence analysis of fitting algorithms on integrated chip topographic modeling

Zhongwei Liang,Bangyan Ye,Yijun Wang,Richard Kars Brauwer 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.10

In inspecting the detailed performance results of surface precision modeling in different external parameter conditions, the integrated chip surfaces should be evaluated and assessed during topographic spatial modeling processes. The application of surface-fitting algorithms exerts a considerable influence on topographic mathematical features. The influence mechanisms caused by different surfacefitting algorithms on the integrated chip surface facilitate the quantitative analysis of different external parameter conditions. By extracting the coordinate information from the selected physical control points and using a set of precise spatial coordinate measuring apparatus,several typical surface-fitting algorithms are used for constructing micro-topographic models with the obtained point cloud. In computing for the newly proposed mathematical features on surface models, we construct the fuzzy evaluating data sequence and present a new three-dimensional fuzzy quantitative evaluating method. Through this method, the value variation tendencies of topographic features can be clearly quantified. The fuzzy influence discipline among different surface-fitting algorithms, topography spatial features, and the external science parameter conditions can be analyzed quantitatively and in detail. In addition, quantitative analysis can provide final conclusions on the inherent influence mechanism and internal mathematical relation in the performance results of different surface-fitting algorithms, topographic spatial features, and their scientific parameter conditions in the case of surface micro modeling. The performance inspection of surface precision modeling will be facilitated and optimized as a new research idea for micro-surface reconstruction that will be monitored in a modeling process.

표면복제법을 이용한 세라믹 복합재료 파괴현상의 투과전자현미경 분석

전형우,김긍호,김병호,Jun, Hyeung-Woo,Kim, Gyeung-Ho,Kim, Byung-Ho 한국현미경학회 1996 Applied microscopy Vol.26 No.4

Fracture surfaces of materials contain useful information ranging from crack path to the mechanism of fracture. Since limitation of electron transparency requires a sample in the form of thin foil for TEM observations, it is impossible to extract such information directly from the fracture surfaces. In this study, the method of surface replication from the ceramic fracture surface is employed to characterize the process of crack propagation in ceramic matrix composites using TEM analysis. The surface replica from the fracture surface in ceramic materials provides detailed surface morphology and more importantly, loosened particles on the fracture surface are collected. Electron diffraction and chemical composition analyses of these particles reveal crack path in the specimen. Furthermore, one can determine the mode of fracture by observing the fracture surface morphology from the image of replica. Two examples are given to illustrate the potential of the surface replication technique. In the first example, apparent toughness increase in $B_{4}C-Al$ composites at high strain rate is investigated by surface replication to elucidate the mechanism of fracture at different strain rates. The polytypes of SiC formed during the sintering of SiC-AlN composite and their effect on the fracture behavior of SiC-AlN composite are analyzed in the second example.

확률론적 응답면 기법을 이용한 저수지 제체의 침투수량 해석

봉태호,손영환,노수각,최우석,Bong, Tae-Ho,Son, Young-Hwan,Noh, Soo-Kack,Choi, Woo-Seok 한국농공학회 2013 한국농공학회논문집 Vol.55 No.3

The seepage quantity analysis of reservoir embankment is very important for assessment of embankment safety. However, the conventional analysis does not consider uncertainty of soil properties. Permeability is known that the coefficient of variation is larger than other soil properties and seepage quantity is highly dependent on the permeability of embankment. Therefore, probabilistic analysis should be carried out for seepage analysis. To designers, however, the probabilistic analysis is not an easy task. In this paper, the method that can be performed probabilistic analysis easily and efficiently through the numerical analysis based commercial program is proposed. Stochastic response surface method is used for approximate the limit state function and when estimating the coefficients, the moving least squares method is applied in order to reduce local error. The probabilistic analysis is performed by LHC-MCS through the response surface. This method was applied to two type (homogeneous, core zone) earth dams and permeability of embankment body and core are considered as random variables. As a result, seepage quantity was predicted effectively by response surface and probabilistic analysis could be successfully implemented.

수치적 방법을 이용한 3차원 거친 표면의 마모 해석

김윤지,서준호,김봉준,유용훈 한국트라이볼로지학회 2020 한국윤활학회지(윤활학회지) Vol.36 No.4

It is essential to predict the amount of wear and surface parameters for a surface where relative motion occurs. In the asperity-based model for wear prediction, only the average contact pressure can be obtained. Hence, the accuracy of wear analysis is poor. In this study, DC-FFT is used to obtain the pressure of each node, and wear analysis is performed by considering the effect of the pressure gradient. The numerical surface generation method is used to create Gaussian, negatively skewed, and positively skewed surfaces for wear analysis. The spatial and height distributions of each surface are analyzed to confirm the effectiveness of the generated surface. Furthermore, wear analysis is performed using DC-FFT and Archard's wear formula. After analysis, it is confirmed that all peaks are removed and only valleys remain on the surface. The RMS roughness and Sk continue to decrease and Ku increases as the cycle progresses. It is observed that the surface parameters are significantly affected by the radius of curvature of the asperity. This analysis method is more accurate than the existing average wear and truncation models because the change in asperity shape during the wear process is reflected in detail.

분광혼합분석 기법을 이용한 탄천유역 불투수율 평가

조홍래 ( Hong Lae Cho ),정종철 ( Jong Chul Jeong ) 大韓遠隔探査學會 2005 大韓遠隔探査學會誌 Vol.21 No.6

도시화에 따른 불투수 지표면의 증가는 도시환경에 부정적인 영향을 미치게 된다. 따라서 도시 내 불투수 지역의 시공간적 변화 사항을 탐색하고 정량화하는 작업은 도시환경을 연구함에 있어 무엇보다 중요한 일이라 할 수 있다. 지난 시기 도시지역의 불투수 지표면을 탐색하는 방법으로는 전통적인 영상분류 기법이 많이 사용되었다. 그러나 기존의 전통적인 영상분류 기법은 영상을 구성하는 각 셀이 지표면에 존재하는 다양한 객체들의 분광특성이 혼합된 결과임에도 불구하고 단 하나의 클래스로만 구분하는 단점을 가진다. 또한 불투수 지표면의 비율을 산정하기 위해서는 영상분류 후 각 분류항목에 불투수율을 할당해야하는 2중의 노력이 필요하며, 각 클래스에 단일한 불투수율을 지정해야만 하는 단점을 갖는다. 본 논문에서는 기존의 영상 분류방법이 갖는 이러한 단점을 보완하고자 불투수 지표면의 비율을 산정하기 위해 분광혼합분석(spectral mixture analysis) 기법을 이용하였다. 분광혼합분석 기법을 적용하기 위해 식생, 토양, low albedo, high albedo 등 4가지 요소를 엔드멤버로 선택하였으며, 불투수율은 low albedo와 high albedo의 합으로 산정하였다. 대상 연구지역은 지난 십여년 동안 급격한 도시화가 진행된 탄천유역을 선정하였으며, 1988, 1994, 2001년의 Landsat 영상을 이용하여 신도시 건설에 따른 불투수 지표면의 변화율을 검토하였다. 분석결과 탄천유역의 불투수율은 88년 15.6%, 94년 20.1%, 2001년 24%로 증가된 것으로 나타났다. 결론적으로 도시 불투수율을 분석 시 분광혼합분석 기법을 적용할 경우 추가적인 노력 없이 비교적 정확한 불투수율을 얻을수 있음을 확인할 수 있었다. Increasing of impervious surface resulting from urban development has negative impacts on urban environment. Therefore, it is absolutely necessary to estimate and quantify the temporal and spatial aspects of impervious area for study of urban environment. In many cases, conventional image classification methods have been used for analysis of impervious surface fraction. However, the conventional classification methods have shortcoming in estimating impervious surface. The DN value of the each pixel in imagery is mixed result of spectral character of various objects which exist in surface. But conventional image classification methods force each pixel to be allocated only one class. And also after land cover classification, it is requisite to additional work of calculating impervious percentage value in each class item. This study used the spectral mixture analysis to overcome this weakness of the conventional classification methods. Four endmembers, vegetation, soil, low albedo and high albedo were selected to compose pure land cover objects. Impervious surface fraction was estimated by adding low albedo and high albedo. The study area is the Tanchon watershed which has been rapidly changed by the intensive development of housing. Landsat imagery from 1988, 1994 to 2001 was used to estimate impervious surface fraction. The results of this study show that impervious surface fraction increased from 15.6% in 1988, 20.1% in 1994 to 24% in 2001. Results indicate that impervious surface fraction can be estimated by spectral mixture analysis with promising accuracy.

표면처리용 형광증백제의 정량분석법에 대한 연구

이지영,김철환,박종혜,김은혜,위상욱,성용주,허영준,김연오,황인영 한국펄프·종이공학회 2015 펄프.종이技術 Vol.39 No.3

Fluorescent whitening agents (FWAs) are widely applied in the papermaking process to improve the CIE whiteness and the ISO brightness of papers. Large amounts of FWAs are used in the paper and paperboard industry, but no standard method exists for quantitative FWA analysis. Therefore, a new method is needed to analyze the presence of FWAs in paper and paperboard to control their additions and applications. In particular, FWA analysis must concentrate on those used for surface treatment of paper because their use in surface applications has increased recently. The purposes of this study were to measure the optical properties of papers surface-treated with oxidized starch containing FWAs and to deduce the regression equations for the quantitative analysis of FWAs used for surface treatments. Surface sizing was carried out to treat the surface of a base paper with T-FWA and H-FWA, and the pickup weight of the surface sized paper was measured to determine the real weight of FWAs transferred onto the paper surface. After surface sizing and preconditioning, the paper was evaluated for CIE whiteness, ISO brightness, fluorescence index, and reflectance at 440 nm using an Elrepho spectrophotometer. The CIE whiteness and the ISO brightness increased linearly as FWA content increased. The fluorescence index and the reflectance showed linear relationships with T-FWA and H-FWA. Linear regression equations were determined for the quantitative analysis of FWAs used for surface treatments.

표면처리용 형광증백제의 정량분석법에 대한 연구

이지영(Ji Young Lee),김철환(Chul Hwan Kim),박종혜(Jong Hye Park),김은혜(Eun Hea Kim),위상욱(Sang Wook Wi),성용주(Yong Joo Sung),허영준(Young Jun Heo),김연오(Yeon Oh Kim),황인영(In Young Hwang) 한국펄프·종이공학회 2015 펄프.종이기술 Vol.47 No.3

Fluorescent whitening agents (FWAs) are widely applied in the papermaking process to improve the CIE whiteness and the ISO brightness of papers. Large amounts of FWAs are used in the paper and paperboard industry, but no standard method exists for quantitative FWA analysis. Therefore, a new method is needed to analyze the presence of FWAs in paper and paperboard to control their additions and applications. In particular, FWA analysis must concentrate on those used for surface treatment of paper because their use in surface applications has increased recently. The purposes of this study were to measure the optical properties of papers surface-treated with oxidized starch containing FWAs and to deduce the regression equations for the quantitative analysis of FWAs used for surface treatments. Surface sizing was carried out to treat the surface of a base paper with T-FWA and H-FWA, and the pickup weight of the surface sized paper was measured to determine the real weight of FWAs transferred onto the paper surface. After surface sizing and preconditioning, the paper was evaluated for CIE whiteness, ISO brightness, fluorescence index, and reflectance at 440 nm using an Elrepho spectrophotometer. The CIE whiteness and the ISO brightness increased linearly as FWA content increased. The fluorescence index and the reflectance showed linear relationships with T-FWA and H-FWA. Linear regression equations were determined for the quantitative analysis of FWAs used for surface treatments.