Dong-Hyuk Kim

Numerical Study on the Impact of the Spatial Resolution of Wind Map in the Korean Peninsula on the Accuracy of Wind Energy Resources Estimation

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.

Validation of Numerical Wind Simulation by Offshore Wind Extraction from Satellite Images

As a part of effort to establish an offshore wind resource assessment system of the Korean Peninsula, a numeric wind simulation using mesoscale climate model MM5 and a spatial distribution of offshore wind extracted from SAR remote-sensing satellite image is compared and analyzed. According to the analyzed results, the numeric wind simulation is found to have wind speed over predication tendency at the coastal sea area. Therefore, it is determined that a high-resolution wind simulation is required for complicated coastal landforms. The two methods are verified as useful ways to identify the spatial distribution of offshore wind by mutual complementation and if the meteor-statistical comparative analysis is performed in the future using adequate number of satellite images, it is expected to derive a general methodology enabling systematic validation and correction of the numeric wind simulation.

Analytic Study on the Variation of Regional Wind Resources Associated with the Change of El Niño/La Niña Intensity

Korea Institute of Energy Research, Daejeon 305-343, KoreaAbstract: In order to clarify the relation between El Nino/La Nina and wind resources of the Korean Peninsula, observedmeteorological data for 20 years were used in this study. Although the wind speed tends to decrease in Eurasia Continent,it gradually increases in the peninsula for 10 years. The seasonal variation of wind speed due to El Nino/La Ninadevelopment is not so small and negative anomalies of SST tend to lead the beginning of the wind speed increase overthe Korean Peninsula. Wind speed variation caused by the global scale meteorological phenomena is more sensitive inmountainous area than in any other areas because of the relatively weak mesoscale forcing at mountainous area.Keywords: wind resources, El Nino/La Nina, SST anomalies, Korean peninsula, wind variation요약: 엘니뇨/라니냐의 강도 변화에 따른 한반도의 풍력자원 변동성을 확인하기 위하여 20년간 장기 지상관측자료를바탕으로 해석적인 분석을 실시하였다. 장기적으로 유라시아 대륙의 풍속 약화경향에도 불구하고 한반도는 최근 10년간풍속 증가가 약하게 나타났다. 그리고 엘니뇨와 라니냐에 따른 한반도 풍속은 계절적으로 다양한 형태를 나타낸다. 지역적으로 음의 해수면 온도 아노말리를 나타내는 라니냐가 발생하면 한반도내 지상풍속이 빨라지는 경향을 가진다. 그리고 기후변화에 대한 풍속은 중규모의 강제력이 가장 미약한 산악지역에서 가장 민감하게 나타난다.주요어: 풍력자원, 엘니뇨/라니냐, 해수면온도변동, 한반도지역, 바람변동

Classification of Wind Sector for Assessment of Wind Resource and Establishment of a Wind Map in South Korea

We classified wind sectors according to the wind features in South Korea. In order to get the information of wind speed and wind direction, we used and improved on the atmospheric numerical model. We made use of detailed topographical data such as terrain height data of an interval of 3 seconds and landuse data produced at ministry of environment, Republic of Korea. The result of simulated wind field was improved. We carried out the cluster analysis to classify the wind sectors using the K-means clustering. South Korea was classified as 8 wind sectors to the annual wind field.

Heat Treatment Processes of A2024 Rheoforging Alloy and Morphology Investigation by Nanoindentation and Atomic Force Microscopy

This study demonstrated nanoindentation techniques of investigating the effects of size and feature in a microstructure on the mechanical properties of rheology-forged aluminum alloy. Mechanical properties and tribological characteristics of rheology-forged Al2024 wrought aluminum alloy in terms of T6 heat treatment were investigated by varying the aging time by nanoindentation and nanoscratch techniques. By nanoindentation/nanoscratch tests and atomic force microscopy, it was demonstrated that the 4 hour aged material exhibites the highest hardness because of the intermediate precipitate phase θ″, which was precipitated by T6 heat treatment at 495°C. Moreover, the friction coefficients in the precipitates in the eutectic phase region were lower than those in the primary α phase region.

Analysis of the Relation between Spatial Resolution of Initial Data and Satellite Data Assimilation for the Evaluation of Wind Resources in the Korean Peninsula

Several numerical experiments were carried out to clarify the influence of satellite data assimilation with various spatial resolution on mesoscale meteorological wind and temperature field. Satellite data used in this study is QuikSCAT launched on ADEOS II. QuikSCAT data is reasonable and faithful sea wind data, which have been verified through many observational studies. And numerical model in the study is MM5 developed by NCAR. Difference of wind pattern with and without satellite data assimilation appeared clearly, especially wind speed dramatically reduced on East Sea, when satellite data assimilation worked. And sea breeze is stronger in numerical experiments with RDAPS and satellite data assimilation than that with CDAS and data assimilation. This caused the lower estimated surface temperature in CDAS used cases. Therefore the influence of satellite data assimilation acts differently according to initial data quality. And it is necessary to make attention careful to handle the initial data for numerical simulations.

Effect of the functional group of silanes on the modification of silica surface and the physical properties of solution styrene-butadiene rubber/silica composites

ABSTRACT Silica compounds were prepared using non-functionalized solution styrene-butadiene rubber (SSBR) to investigate effect of the functional group of silanes on the silica modification and properties of SSBR/silica compounds. Bis-[3-(triethoxysilyl)propyl]disulfide (TESPD), 3-mercaptopropyltriethoxysilane (MPTES), 3-aminopropyltriethoxysilane (APTES), vinyltriethoxysilane (VTES), and 3-chloropropyltriethoxysilane (CPTES) were used as silane agents. Bound rubber contents and vulcanizate structures were analyzed, and physical properties, cure characteristics and viscoelasticities were evaluated. MPTES and TESPD have chemically reactive functional groups with rubber chain. Particulary, as thiol group is more reactive than disulfide, the filler–rubber interaction is outstanding when applying MPTES. The bound rubber content of the MPTES applied compound was 30% higher. Vulcanizate structure analysis exhibited that the filler–rubber interaction of the MPTES applied compound is more than twice as high. As amino group of APTES can form hydrogen bonds with other amino or silanol groups on silica surface, strong filler–filler interaction which leads to easy agglomeration and accelerator adsorption, resulting in flocculation and marching. VTES cannot hydrophobize silica surface owing to its short carbon chain. Therefore, the compounds that apply APTES or VTES had high Payne effect, indicating poor silica dispersion. CPTES has polar functional group but behaves as covering agent because of its weak interaction with rubber.

Suitability Analysis of Onshore Wind Farm using GIS Program and Digital maps

In order to decide the location of appropriate onshore wind farm with higher potential wind energy, several decision processes using Geographic Information System (GIS) including Digital Elevation Map (DEM) were proposed and we also estimated the wind resources through the proposed decision process. Decision process consists with three steps. First step is excluding inappropriate location geographically using DEM data including SRTM (Shuttle Radar Topography Mission) terrain data, landslide, land-use, roadway, and forest road data. And the second step of decision process is consideration of the difficulty caused by the natural environmental problem. This step is carried out using ECVAM (Environmental Conservation Value Assessment Map) data. And final step is determination of the most suitable location through the Moving Suitability Identification Method (MSIM) based on the moving potentially estimated wind resources area. Proposed decision process was applied over the Korean Peninsula. Wind resource potential estimated by the first and the second step is cases shows 35.09 GW and 7.17 GW, respectively, and the total evaluated energy from the all proposed step were 0.43 GW and 1.87 GW for the 3 and 1.5 geographical grid size, respectively.