• Journal of Korea Water Resources Association
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• v.47 no.11
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• pp.1095-1105
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• 2014

A spatial downscaling method using the Support Vector Machine (SVM) Regression for 25 km Tropical Rainfall Measuring Mission (TRMM) Monthly precipitation is proposed. The nonlinear relationship among hydrometeorological variables and precipitation was effectively depicted by the SVM for predicting downscaled grid precipitation. The accuracy of spatially downscaled precipitation was estimated by comparing with rain gauge data from sixty-four stations and found to be improved than the original TRMM data in overall. Especially the positive bias of the original TRMM data was effectively removed after the downscaling procedure. The spatial distributions of 25 km and 1 km grid precipitation were generally similar, while the local spatial trend was better detected by 1 km grid precipitation. The downscaled grid data derived from the proposed method can be applied in hydrological modelling for higher accuracy and further be studied for developing optimized downscaling method incorporation other regression methods.

• Fire Science and Engineering
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• v.29 no.2
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• pp.33-38
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• 2015

For the purpose of high-pressure and suction of fixed amount, the development of ultra-high pressure rotating helical gear positive displacement pump with no clearance had been proceeded. The CFD analysis was performed to verify the internal pressure and the discharge flow velocity of the pump. Accordingly, a flow analysis were performed by FVM technique and we were unable to obtain a successful result since the fluid domain is separated because the grid is not configured in a row in FVM flow analysis of the fully enclosed type without clearance. Because of these problems, the flow analysis was performed by MPS method which grid configuration is not needed and the internal pressure and the discharge flow velocity of the pump were confirmed through the MPS flow analysis. At 1,000 rpm rotation speed of the rotor, the minimum internal pressure of the pump was 19.5 bar, maximum pressure was 44.6 bar and average pressure was 33.9 bar. And the minimum discharge flow velocity was 64.5 m/s, maximum discharge flow velocity was 84.8 m/s and average discharge flow velocity was 76.1 m/s. Through this study, we could confirm that MPS method was more suitable than FVM method in terms of flow analysis with no clearance. In addition, the relationship of the flow velocity according to the change of ultra-high pressure rotating helical gear positive displacement pump could be identified through this study.

• Journal of the Korean Electrochemical Society
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• v.3 no.2
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• pp.90-95
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• 2000

Cycle life test was carried out to evaluate the failure modes of the gel type nth batteries at $C_5$ currents and $100\%$ DOD. When the batteries were charged at constant voltage of 2.40 V and 2.50 Vi respectively, cycle lift was over 1,000 cycles. The batteries lost 426.4 g and 391.2 g of electrolyte far each case after the weight measurement. The battery charged at 2.50 V was shown to have a better cyclic performance than charged at 2.40 V, and the amounts of electrolyte loss was proportional to charge factor. After cycle test, the micro-structure of positive active material was completely changed and the corrosion layer of positive grid was about $50{\mu}m$. Failure mode of the positive plate of the gel type battery was a shedding of the positive active material, and the cause of discharge capacity decrease was found to be a electrolyte loss.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.123-126
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• 2022

We investigated deep levels in n-type 4H-SiC epitaxy layer of the Positive-Intrinsic-Negative diode and Schottky barrier diodes by using deep level transient spectroscopy. Despite the excellent performance of 4H-SiC, research on various deep level defects still requires a lot of research to improve device performance. In Positive-Intrinsic-Negative diode, two defects of 196K and 628K are observed more than Schottky barrier diode. This is related to the action of impurity atoms infiltrating or occupying the 4H-SiC lattice in the ion implantation process. The I-V characteristics of the Positive-Intrinsic-Negative diode shows about ~100 times lower the leakage current level than Schottky barrier diode due to the grid structures in Positive-Intrinsic-Negative. As a result of comparing the capacitance of devices diode and Schottky barrier diode devices, it can be seen that the capacitance value lowered if it exists the P implantation regions from C-V characteristics.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.129-143
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• 2015

Increasing concerns on climate change and energy security accelerated policies to reduce green-house gas emission, especially from the transportation sector. Electric vehicle (EV) has been on the spotlight to deal with such environmental issue and V2G (Vehicle-to-Grid) technology began to draw attentions as an alternative to reduce ownership costs while contributing to an efficient and decentralized power grid. This study conducts a scenario analysis on total cost of ownership of EV under V2G scheme and compare with non-V2G EV and Internal Combustion Engine (ICE) vehicle. As result, V2G service is expected to provide an annual average profit of $210 to EV users willing to reverse flow its residual power in the battery. The profit from V2G service leaves a margin of $4,530 over operational lifetime, compared with $2,420 cost of charge for non-V2G EV. In summary, total cost of ownership of V2G-capable EV was 6.2% less than non-V2G EV and 10.2% higher than ICE vehicle. The results confirm a comparative economic advantage of operating EV under V2G scheme. Increased number of EVs with V2G service has shown to provide positive effects to power industry for valley filling in load distribution, thus, favorably increasing the overall economic feasibility.

• Archives of design research
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• v.11
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• pp.22-29
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• 1995

I have to find standpoint of sight moulding of Chi I Sung Hwa(seven stars picture) analysis of graphic systems of a symbol sight native to our nation. And I will comprehend emotion of folkways by simple and graphic lines and colors in mathematical Grid of which ancestor had expressed in gauge moulding consciousness. This papers aim is to make a contribution to lead by on part of communication design. About structural analysis of pictorial graphic side. I) Mathematical thought of the Orient and space constitution are first basically the Orient expressed number notion of mathematics of unlimitedness and notion of zero so called space and empty second can analigize a diagonal expansion method by development of symmetry notion to basic the dual principle of the negative and positive by degrees development expressed space division method by direction notion. 2) About the proportion analysis it based the golden section globularity and in modern layout it takes vision center of position, after appointing the brow of sacred image of Chil Sung Hwa as center point of proportion and applied to the point proportion and so analigized the posibility of established. Rule in union of each elements and rule of forms about picture image. 3) Mathematical structure analysis to search a unified principle at the balanced arrangement and rule of forms it analigized the standard the rule of forms. it analigized the standard the rule of forms to body module of basic movement of protagonist and follower above basic forms of grid that is the basis of design system.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.1
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• pp.59-66
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• 2000

This study describes the precise DTM by image processing method through scanning the positive film of aerial photo using scanner instead of plotter. First, scanned the positive film of aerial photo by drum scanner and flatbed scanner in different resolution, and then compared the height from image processing method using auto correlation method with height which is taken using $50^m{\times}50^m$ grid in 1 :5,000 geographical map. It shows that heights from aerial photo image of high resolution obtained from scanner are comparable to the heights from 1：5,000 geographical map.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.398-403
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• 2003

Dynamic Voltage Restorers (DVR)s are known as the best effective and economic means to compensate for voltage sags and swells [1]-[11]. This paper proposes a novel method to generate reference voltages synchronized with the grid whether the line voltages are distorted by a fault or not. The proposed reference wave generator (RWC) looks for the original wave forms from the corrupted line voltages and synthesizes the expected positive sequence reference waves for DVRs. There is no transient problem on the generated reference waves when the line voltages are distorted by the fault.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.210-214
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• 2007

Silicon nanoparticles are widely studied as a material with great potential for wide applications. For application to present industry, it should be easy to control the characteristics of nanoparticle including the size and structure. In this paper, we investigated the formation of Si nanoparticle using pulse plasma technology. Plasma technology is already quite common in device industry and the size of nanoparticle can be easily controlled according to plasma pulse duration. An inductively-coupled plasma chamber with RF power (13.56 MHz) was used with DC-biased grid $(-200\sim+200\;V)$ installed above the substrate. In order to measure the shape and size of nanoparticle, TEM was used. It was found that the size of nanoparticles can be controlled well with the plasma pulse duration and the collection efficiency is increased with the use of either negative or positive DC-bias.

• Advances in robotics research
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• v.1 no.2
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• pp.127-140
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• 2014

This work presents an IR-based system for parking assistance and obstacle detection in the automotive field that employs the Microsoft Kinect camera for fast 3D point cloud reconstruction. In contrast to previous research that attempts to explicitly identify obstacles, the proposed system aims to detect "reachable regions" of the environment, i.e., those regions where the vehicle can drive to from its current position. A user-friendly 2D traversability grid of cells is generated and used as a visual aid for parking assistance. Given a raw 3D point cloud, first each point is mapped into individual cells, then, the elevation information is used within a graph-based algorithm to label a given cell as traversable or non-traversable. Following this rationale, positive and negative obstacles, as well as unknown regions can be implicitly detected. Additionally, no flat-world assumption is required. Experimental results, obtained from the system in typical parking scenarios, are presented showing its effectiveness for scene interpretation and detection of several types of obstacle.