• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.24 no.1
• /
• pp.16-25
• /
• 2012

To calculate the total mass flux that change in dry and flood season in the Yeomha Channel of Gyeonggi Bay, the 13 hour bottom tracking observation was performed from the southern extremity. The value of the total mass flux(Lagrange flux) was calculated as the sum of the Eulerian flux value and stroke drift value and the tidal residual flow was harmonically analyzed through the least-squares method. Moreover, the average during the tidal cycle is essential to calculate the mass flux and the tidal residual flow and there is the need to equate the grid of repeatedly observed data. Nevertheless, due to the great differences in the studied region, the number of vertical grid tends to change according to time and since the horizontal grid differs according to the transport speed of the ship as a characteristic of the bottom tracking observation, differences occur in the horizontal and vertical grid for each hour. Hence, the present study has vertically and horizontally normalized(sigma coordinate) to equate the grid per each hour. When compared to the z-level coordinate system, the Sigma coordinate system was evaluated to have no irrationalities in data analysis with 5% of error. As a result of the analysis, the tidal residual flow displayed the flow pattern of sagging in the both ends in the main waterway direction of dry season. During flood season, it was confirmed that the tidal residual flow was vertical 2-layer flow. As a result of the total mass flux, the ebb properties of 359 cm/s and 261 cm/s were observed during dry and flood season, respectively. The total mass flux was moving the intertidal region between Youngjong-do and Ganghwa-do.

• Journal of Korea Multimedia Society
• /
• v.19 no.2
• /
• pp.504-511
• /
• 2016

3D simulation programs or games on a smart phone and a personal computer have often employed 3D graphic processing techniques and 3D graphical views. However, the user interfaces in those 3D programs have sticked to take a typical 2D style user interface and thus the combination of a 2D user interface view and a 3D simulation view give us a mismatched sense. Since a 2D user interface has been based on the windows controls, it causes sometime DC conflicts between a simulation view and an interface view. Therefore, we will implement the UI developing tool which can be inserted into the pipeline structure for the development of a 3D simulation software and also follows the view-handler design pattern in Microsoft windows system. It will provide various graphical effects such as the deformation of UI depending on the view direction of simulation view and the sitting pose of user. This developing tool gives the natural user interface which heightens the sense of unity with a given 3D simulation view.

• Journal of The Korean Digital Architecture Interior Association
• /
• v.11 no.1
• /
• pp.43-51
• /
• 2011

Thanks to the historic sites, the identity of historical landscape of Gyeongju is definitely recognized. When explaining, in other words, the identity of urban scape, we have to know the characteristics of landscape with the changes of the times. Therefore this study is tried to understand the urban scape form and meaning of the historic city Gyeongju, futhermore to find out the identity of urban scape, catching hold of the characteristics of landscape by periods. The research was proceeded through the classifying the concept of Urban form by periods and the basic ideology and adopting the representative landscape at that time with the literatures and maps in the Silla period. And then tried to find out the identity of landscape with the link between the concepts of the representative landscape and that of Urban form in chronological order. The results of this study is relativeness between city and natural environment, type of the Grid - Pattern on urban form, basic ideals were inspired by Buddhism.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.91.2-91.2
• /
• 2010

The use of plated front contact for metallization of silicon solar cell may alternative technologies as a screen printed and silver paste contact. This technologies should allow the formation of contact with low contact resistivity a high line conductivity and also reduction of shading losses. The better performance of Ni/Cu contacts is attributed to the reduced series resistance due to better contact conductivity of Ni with Si and subsequent electroplating of Cu on Ni. The ability to pattern narrower grid lines for reduced light shading combined with the lower resistance of a metal silicide contact and improved conductivity of plated deposit. This improves the FF as the series resistance is deduced. This is very much required in the case of low concentrator solar cells in which the series resistance is one of the important and dominant parameter that affect the cell performance. A selective emitter structure with highly dopes regions underneath the metal contacts, is widely known to be one of the most promising high-efficiency solution in solar cell processing. This paper using selective emitter structure technique, fabricated Ni/Cu plating metallization cell with a cell efficiency of 17.19%.

• Journal of Korea Multimedia Society
• /
• v.20 no.8
• /
• pp.1369-1378
• /
• 2017

Pub/Sub (Publish/Subscribe) paradigm is a simple and easy to use model for interconnecting applications in a distributed environment. In general, subscribers register their interests in a topic or a pattern of events and then asynchronously receive events matching their interest, regardless of the events' publisher. In order to build a low latency lightweight pub/sub system for Internet of Things (IoT) services, we propose a GQSFPS (Group Quorum System-based Fog Pub/Sub) system that is a core component in the event-driven service oriented architecture framework for IoT services. The GQSFPS organizes multiple installed pub/sub brokers in the fog servers into a group quorum based P2P (peer-to-peer) topology for the efficient searching and the low latency accessing of events. Therefore, the events of IoT are cached on the basis of group quorum, and the delay-sensitive IoT applications of edge devices can effectively access the cached events from group quorum fog servers in low latency. The performance of the proposed GQSFPS is evaluated through an analytical model, and is compared to the GQPS (grid quorum-based pud/sub system).

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.4
• /
• pp.325-333
• /
• 2015

This study was devoted to elucidating the change in the flow characteristics of a laminar flow past a circular cylinder by modifying the cylinder shape with O-grooves. A numerical analysis was performed in a two-dimensional framework. The cylinder was represented using an immersed boundary method and marker particles on a Cartesian grid system. The number and locations of the O-grooves were the key parameters. An analysis of the flow pattern and flow-induced forces was performed at Re = 40 and 50. In addition, we calculated the critical Reynolds number depending on the number of O-grooves and their locations.

• Journal of Korean Society for Atmospheric Environment
• /
• v.13 no.6
• /
• pp.463-474
• /
• 1997

Metallic elements in dustfall have been known as notable air pollutants directly or indirectly influencing human health and wealth. The first aim of this study was to obtain precise spatial distribution patterns of 5 elements (Pb, Zn, K, Cr, and Al) in dustfall around Suwon area. To predict isometric lines of metal fluxes deposited on unsupervised random sites, the study has applied both spatial statistics as a receptor model and a GIS (geographic information system). Total of 31 sampling sites were selected in the study area (roughly 3 by 3 km grid basis) and dustfall samples were then collected monthly basis by the British deposit gauges from Dec., 1995 to Nov., 1996. The metallic elements in the dustfall were then analyzed by an atomic absorption spectrometer (AAS). On the other hand, a base map overlapped by 7 layers was constructed by using the AutoCAD R13 and ARC/INFO 3.4D. Four different spatial interpolation and expolation techniques such as IDW (inverse distance weighted averaging), TIN (triangulated irregular network), polynomial regression, and kriging technique were examined to compare spatial distribution patterns. Each pattern obtained by each technique was substantally different as varing pollutant types, land of use types, and topological conditions, etc. Thus, our study focused intensively on uncertainty analysis based on a concept of the jackknife and the sum of error distance. It was found that a kriging technique was the best applicalbe in this study area.

• Journal of Mechanical Science and Technology
• /
• v.14 no.8
• /
• pp.816-822
• /
• 2000

In the core of the nuclear power plant of PWR, several cases of fuel failure by unknown causes have been experienced for various fuel types. From the common features of the failure pattern, failure lead time, flow conditions, and flow induced vibration characteristics in nuclear fuel bundles, it is deduced that the fretting wear failure of the fuel rod at the spacer grid position is due to the fluidelastic vibration. In the past, fluidelastic vibration was simulated by quasi -static semi-analytical model, so called the static model, which could not account for the interaction between the rods within a bundle. To overcome this defect and to provide for more flexibilities applicable to the fuel bundle, Tanaka's unsteady model was modified to accomodate the geometrical differences and governing parameter changes during the operations such as the number of rods, pitch to diameter ratio (P/D), spring force, damping coefficient, etc. The critical velocity was calculated by solving the governing equations with the MATLAB code. A comparison between the estimated critical velocity and the test result shows a good agreement. Finally, the level of decrease of the critical velocity due to the reduction in the spring force and reduced damping coefficient due to the radiation exposure is also estimated.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.10a
• /
• pp.279-283
• /
• 2009

Distributed generation(DG) of combined cooling, heat. and power(CCHP)has been gaining momentum in recent year as efficient, secure alternative for meeting increasing energy demands. This paper presents the energy performance of microturbine CCHP system equipped with an absorption chiller by modelling it in hospital building. The orders of study were as following. 1)The list and schedule of energy consumption equipment in hospital were examined such as heating and cooling machine, light etc. 2) Annual report of energy usage and monitoring data were examined as heating, cooling, DHW, lighting, etc. 3) The weather data in 2007 was used for simulation and was arranged by meteorological office data in Daejeon. 4) Reference simulation model was built by comparison of real energy consumption and simulation result by TRNSYS and ESP-r. The energy consumption pattern of building were analyzed by simulation model and energy reduction rate were calculated over the cogeneration. As a result of this study, power generation efficiency of turbine was about 30% after installing micro gas turbine and lighting energy as well as total electricity consumption can be reduced by 40%. If electricity energy and waste heat in turbine are used, 56% of heating energy and 67% of cooling energy can be reduced respectively, and total system efficiency can be increased up to 70%.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.4
• /
• pp.1369-1375
• /
• 2017

This paper presents an optimal operation scheduling algorithm for a smart home with energy storage system, electric vehicle and distributed generation. The proposed algorithm provides the optimal charge and discharge schedule of the EV and the ESS. In minimizing the electricity costs of the smart home, it considers not only the cost of energy purchase from the grid but also the life cost of batteries. The life costs of batteries are calculated based on the relation between the depth of discharge and life time of battery. As the life time of battery depends on the charge and discharge pattern, optimal charge and discharge schedule should consider the life cost of batteries especially when there is more than one battery with different technical characteristics. The proposed algorithm can also be used for optimal selection of size and type of battery for a smart home.