• Spatial Information Research
• /
• v.22 no.4
• /
• pp.39-47
• /
• 2014

The Yeongsan river estuary has a serious water quality problem due to the water stagnation and it is imperative to predict the changes of water quality for mitigating water pollution. EFDC(Environmental Fluid Dynamics Code) model was mainly utilized to predict the changes of water quality for the estuary. The EFDC modeling normally accompanies the large volume of modeling output. For checking the spatial distribution of the modeling results, post-processing for converting of the output is prerequisite and mainly post-processing program is EFDC_Explorer. However, EFDC_Explorer only shows the spatial distribution of the time series and this doesn't support overlay function with other thematic maps. This means the impossible to the connection analysis with a various GIS data and high dimensional analysis. Therefore, this study aims to develop a post-processing system of a EFDC output to use them as GIS layers. For achieving this purpose, a editing module for main input files, and a module for converting binary format into an ASCII format, and a module for converting it into a layer format to use in a GIS based environment, and a module for visualizing the reconfigured model result efficiently were developed. Using the developed system, result file is possible to automatically convert the GIS based layer and it is possible to utilize for water quality management.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.11 s.353
• /
• pp.118-127
• /
• 2006

The wireless transmission medium inherently broadcasts a signal to all neighbor nodes in the transmission range. Existing asynchronous MAC protocols do not provide a concrete solution for reliable broadcast in link layer. This mainly comes from that an omnidirectional broadcasting causes to reduce the network performance due to the explosive collisions and contentions. This paper proposes a directional broadcast protocol by using neighborhood information in the link layer based o,1 directional antennas, named MNDB (MAC protocol with Neighborhood for reliable Directional Broadcast). This protocol makes use of neighborhood information and DMACA (Directional Multiple Access and Collision Avoidance) scheme through 4-way handshake to support a reliable directional broadcast. To analyze its performance, MNDB protocol si compared with $RMDB^{[1]}$, the protocol 2 of reference [3], and IEEE 802.11 $protocol^{[9]}$, in terms of the number of collisions, the number of dropped packets, the number of redundant packets, and broadcast delay.

• Journal of Welding and Joining
• /
• v.33 no.5
• /
• pp.53-60
• /
• 2015

Laser surface Melting Process is getting hardening layer that has enough depth of hardening layer as well as no defects by melting surface of substrate. This study used CW(Continuous Wave) Yb:YAG and STD11. Laser beam speed, power and beam interval are fixed at 70mm/sec, 2.8kW and 800um respectively. Hardness in the weld zone are equal to 400Hv regardless of melting zone, remelting zone overlapped by next beam and HAZ. Similarly, microstructures in all weld zone consist of dendrite structure that arm spacing is $3{\sim}4{\mu}m$, matrix is ${\gamma}$(Austenite) and dendrite boundary consists of ${\gamma}$ and $M_7C_3$ of eutectic phase. This microstructure crystallizes from liquid to ${\gamma}$ of primary crystal and residual liquid forms ${\gamma}$ and $M_7C_3$ of eutectic phase by eutectic reaction at $1266^{\circ}C$. After solidification is complete, primary crystal and eutectic phase remain at room temperature without phase transformation by quenching. On the other hand, microstructures of substrate consist of ferrite, fine $M_{23}C_6$ and coarse $M_7C_3$ that have 210Hv. Microstructures in the HAZ consist of fine $M_{23}C_6$ and coarse $M_7C_3$ like substrate. But, $M_{23}C_6$ increases and matrix was changed from ferrite to bainite that has hardness above 400Hv. Partial Melted Zone is formed between melting zone and HAZ. Partial Melted Zone near the melting zone consists of ${\gamma}$, $M_7C_3$ and martensite and Partial Melted Zone near the HAZ consists of eutectic phase around ${\gamma}$ and $M_7C_3$. Hardness is maximum 557Hv in the partial melted zone.

• Journal of Wetlands Research
• /
• v.13 no.3
• /
• pp.707-720
• /
• 2011

For the lake case, the detention phenomenon of water body occurs and stays for a long time. Especially, following the layer of water depth direction, the lake body and water quality problems are different from the water quality of river. So according to time, the stream and water quality can be simulated by the 3-Dimensional Model, which can divide water layer for reservoir or lake. The water quality simulation result will become more reliability. For this study, the 3-Dimension Model - EFDC was used to simulate water quality of Unam reservoir in the Sumjin Dam. The HEC-GeoHMS and HEC-HMS Rainfall - Runoff Model based on GIS were used to estimate long-term runoff, and input data was constructed to the observed water level, meteorological data, water temperature, T-N and T-P. In order to apply the EFDC model, water depth was divided into 3 layers and 5,634 grids were extracted. After constructing the grid net, the water quality change of Unam reservoir in time and space was simulated. Overall, long term runoff simulation reflected the actual observed runoff well, through the water quality simulation, according to the pollution factors, the behavior characteristics can be checked, and the simulated water quality can be properly reflected. The function of EFDC has been confirmed, which water quality can be properly simulated. In the near future, to establish countermeasures for Intake Facilities of Watershed and Management, this support which some basic tools can be applied is in expectation.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.36 no.3
• /
• pp.39-51
• /
• 2008

This study focuses on the reconstruction of buffer greens which were installed to reduce environmental effects on roadsides constructed in the 1980s, in order to supplement various urban green functions. The subjects were buffer greens installed along the Songpadaero and Nambusunwhanro in Songpa-gu. Planting was suggesting to strengthen the buffer, landscape, shading and ecological function according to the use of the buffer green surroundings. The surroundings of the green axis subjects are high-rise apartment areas, neighboring commercial areas, commercial working areas, transportation facility areas, urban support facility areas, schools, parks, etc. However, the structure of the buffer greens were uniformed with Plantanus occidentalis and Ginkgo biloba and Zelkova serrata in the canopy layer and with Forsythia koreana and Ligustrum obtusifoliumin the shrub layer in lineal or alternate order, functioning only as buffer space. Therefore, the buffer greens need to be reconstructed， supplementing various functions according to land use, in order to improve the pedestrian walk area in terms of landscape and use of greens. In line with that, the planting improvement plans according to the land use patterns, and physical and ecological structure were classified into buffer and landscape, landscape and buffer, buffer and shading, and buffer and ecological function. In addition, improving planting function, species and facilities are suggested.

• Journal of Institute of Convergence Technology
• /
• v.6 no.2
• /
• pp.35-40
• /
• 2016

Ignitor tip is a component of burner to start the burning process in power plant. This is used to ignite the coal to a constant operating state by fuel mixed with air and kerosene. This component is composed of three components so that air and kerosene are mixed in the proper ratio and injected uniformly. Because the parts with the designed shape are manufactured in the machining process, they have to be made of three parts. These parts are designed to have various functions in each part. The mixing part mixes the supplied air and kerosene through the six holes and sends it to the injecting part at the proper ratio. The inject part injects mixed fuel, which is led to have a constant rotational direction in the connecting part, to the burner. And the connecting plate that the mixed fuel could rotate and spray is assembled so that the flame can be injected uniformly. But this part causes problems that are worn by vibration and rotation because it is mechanically assembled between the mixing part and the inject part. In this study, 3D printing method is used to integrate a connecting plate and an inject part to solve this wear problem. The 3D printing method could make this integrated part because the process is carried out layer by layer using a metal powder material. The part manufactured by 3D printing process should perform the post process such as support removal and surface treatment. However, while performing the 3D printing process, the material properties of the metal powders are changed by the laser sintering process. This change in material properties makes the post process difficult. In consideration of these variables, we have studied the optimization of manufacturing process using 3D printing method.

• Journal of Korea Multimedia Society
• /
• v.11 no.5
• /
• pp.710-727
• /
• 2008

Service-oriented computing systems have been issued by their properties of reducing software development time and effort by reusing functional service units. The reusability of services can effectively promote through loose coupling between services. But strong associations of object-oriented systems such as inheritance and aggregation create a rather tight coupling between objects. The component-based systems without inheritance and aggregation create a loose coupling between components. Thus components provide service realization at runtime using the functionality provided by their interfaces. Therefore legacy component-based systems need to have service-oriented computing concept in order to support functional service units efficiently. Also, conventional methods for service-oriented computing system have not suggested the clear classification of service layers, the clear service identification guideline introducing service layers and a service mapping method between serviceces of each layer. Therefore we suggest the service classification and the identification guideline of business view and implementation view introducing layers and propose a mapping between two views. That is, we research service layers, service identification, diversified service sizes and a service mapping method between services of each layer. This can be applied to legacy component-based system to extend to the service-oriented computing system.

• Journal of the Korean Ceramic Society
• /
• v.39 no.5
• /
• pp.503-510
• /
• 2002

Silicon carbide candle filters for the pressurized fluidized bed combustion system were fabricated by extrusion process. Carbon black was added to control the porosity. Inorganic additives such as clay and calcium carbonate were added to exhibit appropriate strength. Silicon carbide layer with a finer pore size (mean pore diameter ~$10{\mu}m$) was coated on the silicon carbide support layer (mean pore diameter ~$47{\mu}m$, porosity ∼40%). After that, the filter was sintered at 1400${\circ}C$ in air. We evaluated the filtration performances of the filter at 500${\circ}C$ and $5kgf/cm^2$ of pressure. As a result, high separation efficiency, >99.999% was measured. It is expected that silicon carbide candle filter can be successfully used for the pressurized fluidized bed combustion system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.4
• /
• pp.795-803
• /
• 2017

This paper describes a dual-standard cryptographic processor that efficiently integrates two block ciphers ARIA and AES into a unified hardware. The ARIA-AES crypto-processor was designed to support 128-b and 256-b key sizes, as well as four modes of operation including ECB, CBC, OFB, and CTR. Based on the common characteristics of ARIA and AES algorithms, our design was optimized by sharing hardware resources in substitution layer and in diffusion layer. It has on-the-fly key scheduler to process consecutive blocks of plaintext/ciphertext without reloading key. The ARIA-AES crypto-processor that was implemented with a $0.18{\mu}m$ CMOS cell library occupies 54,658 gate equivalents (GEs), and it can operate up to 95 MHz clock frequency. The estimated throughputs at 80 MHz clock frequency are 787 Mbps, 602 Mbps for ARIA with key size of 128-b, 256-b, respectively. In AES mode, it has throughputs of 930 Mbps, 682 Mbps for key size of 128-b, 256-b, respectively. The dual-standard crypto-processor was verified by FPGA implementation using Virtex5 device.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.493-493
• /
• 2014

The manufacturing cost of thin-film photovoltics can potentially be lowered by minimizing the amount of a semiconductor material used to fabricate devices. Thin-film solar cells are typically only a few micrometers thick, whereas crystalline silicon (c-Si) wafer solar cells are $180{\sim}300\mu}m$ thick. As such, thin-film layers do not fully absorb incident light and their energy conversion efficiency is lower compared with that of c-Si wafer solar cells. Therefore, effective light trapping is required to realize commercially viable thin-film cells, particularly for indirect-band-gap semiconductors such as c-Si. An emerging method for light trapping in thin film solar cells is the use of metallic nanostructures that support surface plasmons. Plasmon-enhanced light absorption is shown to increase the cell photocurrent in many types of solar cells, specifically, in c-Si thin-film solar cells and in poly-Si thin film solar cell. By proper engineering of these structures, light can be concentrated and coupled into a thin semiconductor layer to increase light absorption. In many cases, silver (Ag) nanoparticles (NP) are formed either on the front surface or on the rear surface on the cells. In case of poly-Si thin film solar cells, Ag NPs are formed on the rear surface of the cells due to longer wavelengths are not perfectly absorbed in the active layer on the first path. In our cells, shorter wavelengths typically 300~500 nm are also not effectively absorbed. For this reason, a new concept of plasmonic nanostructure which is NPs formed both the front - and the rear - surface is worth testing. In this simulation Al NPs were located onto glass because Al has much lower parasitic absorption than other metal NPs. In case of Ag NP, it features parasitic absorption in the optical frequency range. On the other hand, Al NP, which is non-resonant metal NP, is characterized with a higher density of conduction electrons, resulting in highly negative dielectric permittivity. It makes them more suitable for the forward scattering configuration. In addition to this, Ag NP is located on the rear surface of the cell. Ag NPs showed good performance enhancement when they are located on the rear surface of our cells. In this simulation, Al NPs are located on glass and Ag NP is located on the rear Si surface. The structure for the simulation is shown in figure 1. Figure 2 shows FDTD-simulated absorption graphs of the proposed and reference structures. In the simulation, the front of the cell has Al NPs with 70 nm radius and 12.5% coverage; and the rear of the cell has Ag NPs with 157 nm in radius and 41.5% coverage. Such a structure shows better light absorption in 300~550 nm than that of the reference cell without any NPs and the structure with Ag NP on rear only. Therefore, it can be expected that enhanced light absorption of the structure with Al NP on front at 300~550 nm can contribute to the photocurrent enhancement.