• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.4
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• pp.236-243
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• 2007

Radio frequencies used by the logistics of RFID in various areas, including research the core of ubiquitous computing. Moreover, RFID and the convergence of mobile terminals RFID research started as a B2B service area, B2C services and the expansion of the zone. B2B2C to in order to provide services ranging from mobile terminals for RFID technology development is needed. We develop middleware for a mobile RFID terminal. It consists of multi-code recognition module, the reader control module, the module code interpretation, and Dispatcher module. We present the implementation of these functions on an emulator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.8
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• pp.688-695
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• 2014

In a small wireless environment, such as your home or office, a various network using WiMedia PHY can be mixed. Because these networks operate independently for each application, data conflict can occur between adjacent networks. To avoid data conflict, the resource in a different time zone can be utilized. However, if devices in a network increase, available resources in the network decrease, and then the lack of resources necessary to provide service can occur. To solve this problem, we propose collision avoidacne scheme for coexistence of various UWB systems. In this paper, we evaluate the performance of the proposed scheme through simulation.

• Steel and Composite Structures
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• v.29 no.2
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• pp.175-186
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• 2018

The plastic hinge method and the plastic zone method are extensively adopted in displacement-based elements and force-based elements respectively for second-order inelastic analysis. The former enhances the computational efficiency with relatively less accurate results while the latter precisely predicts the structural behavior but generally requires more computer time. The displacement-based elements receive criticism mainly on plasticity dominated problems not only in accuracy but also in longer computer time to redistribute the forces due to formation of plastic hinges. The multi-element-per-member model relieves this problem to some extent but will induce a new problem in modeling of member initial imperfections required in design codes for direct analysis. On the contrary, a force-based element with several integration points is sufficient for material yielding. However, use of more integration points or elements associated with fiber section reduces computational efficiency. In this paper, a new force-based element equipped with stress-resultant plasticity model with minimal computational cost is proposed for second-order inelastic analysis. This element is able to take the member initial bowing into account such that one-element-per-member model is adequate and complied with the codified requirements of direct analysis. This innovative solution is new and practical for routine design. Finally, several examples demonstrate the validity and accuracy of the proposed method.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.745-750
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• 2009

In Korea, since the implementation of the GMO Law, the intrest of biosafety level 3(BL3) lab. is increasing. In this study, using CONTAM which is applying multizone modelling, the multizone simulation for design verification of BL3 lab. was performed. In BL3 lab., because required air change rate is greater than general estimated air-conditioning load and it is difficult to maintain room pressure difference efficiently, to maintain pressure difference between laboratory rooms is important through sealing condition of doors and proper airflow control of laboratory rooms. In this study, about BL3 lab.(M. tuberculosis research lab.), the multizone simulation for four kind of biohazard scenarios was performed in the case of unexpected spread of contaminants in the laboratory room, anteroom, corridor and inside of BSC. Multizone simulation results show that these approach methods are used as a tool for the design and verification of BL3 lab.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.564-568
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• 2007

Gas hydrate has been attractive topic for two dedicates because it may cause the global warming, ocean hazards associated with the instability of marine slope due to the gas hydrate release as well as high potential of future energy resources. The study on gas hydrate in Ulleung basin has been performed since 1999 to explore the potential and distribution of gas hydrate offshore Korea. The numerous multi channel seismic data have been acquired and processed by Korea Institute of Geosciences and Mineral Resources (KIGAM). The results showed clearly the gas hydrate indicators such as pull up structure, bottom simulating reflector (BSR), seismic blanking zone. The prestack depth migration has been considered as fast and accurate technique to image the subsurface. In this paper, we will present both the conventional seismic data processing and apply Kirchhoff prestack depth migration for gas hydrate data set. The results will be applied for core sample collections and for proposal more detail 2D with long offset or 3D seismic exploration.

• Journal of Ocean Engineering and Technology
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• v.23 no.1
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• pp.16-23
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• 2009

The three-dimensional ship motion with forward speed was solved by a finite element method in the time domain. A boundary value problem was described in the frame of a fixed-body reference, and the problem was formulated according to Double-Body and Neumann-Kelvin linearizations. Laplace's equation with boundary conditions was solved by a classical finite element method based on the weak formulation. Chebyshev filtering was used to get rid of an unwanted saw-tooth wave and a wave damping zone was adopted to impose a numerical radiation condition. The time marching of the free surface was performed by the 4th order Adams-Bashforth-Moulton method. Wigley I and Wigely III models were considered for numerical validation. The hydrodynamic coefficients and wave exciting forces were validated by a comparison with experimental data and the numerical results of the Wigley I. The effects of the linearization are also discussed. The motion RAO was also checked with a Wigley III model through mono-chromatic and multi-chromatic regular waves.

• Journal of Advanced Marine Engineering and Technology
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• v.9 no.4
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• pp.328-338
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• 1985

When the low temperature service steels are used as materials for welded structure, some problems-brittleness and weld cracking, etc.-occur in welded part due to the change of mechanical and metallurgical characteristics resulted from the thermal cycle during the welding procedure. In this study, the experiments were conducted to investigate the change of mechanical and metallurgical characteristics of the welded part for the low temperature and high pressure service steels. Moreover, the Static and Dynamic Implant Test Method was introduced to this study in order to find out the mechnism of weld cracking. In addition, the fracture toughnesses of welded bond were inspected under the various low temperature environments. Main results obtained are as follows; 1) The effect of the hydrogen on the fatigue characteristics of the weld bond can be estimated by the new self-contrived Dynamic Implant Test equipment. 2) The fine micro-structure and low hardness in the heat affected zone can be obtained by the small heat input multi-pass welding. 3) The susceptibility of the delayed cracking is largely affected by the condition of used electrode. 4) The transition temperature of the fracture surface in weld bond appears to be higher 20 .deg. C than that in base metal.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.98-103
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• 2008

This paper is to discuss distribution of welding residual stresses of a ferritic low alloy steel nozzle with dissimilar metal weld using Alloy 82/182. Two dimensional (2D) thermo-mechanical finite element analyses are carried out to simulate multi-pass welding process on the basis of the detailed and fabrication data. On performing the welding analysis generally, the characteristics on the heat input and heat transfer of weld are affected on the weld residual stress analyses. Thermal analyses in the welding heat cycle process is very important process in weld residual stress analyses. Therefore, heat is rapidly input to the weld pass material, using internal volumetric heat generation, at a rate which raises the peak weld metal temperature to $2200^{\circ}C$ and the base metal adjacent to the weld to about $1400^{\circ}C$. These are approximately the temperature that the weld metal and surrounding base materials reach during welding. Also, According to the various ways of appling the weld heat source, the predicted residual stress results are compared with measured axial, hoop and radial through-wall profiles in the heat affected zone of test component. Also, those results are compared with those of full 3-dimensional simulation.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.220-227
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• 2000

The purpose of this study is to develop the non-gravity fluidized dryer. In this non-gravity fluidized dryer the fluidized zone is produced by two paddles in mixer, which maximizes the surface area of materials and then heated air through the guiding panels dehumidify them. This can conduct the drying process quickly and control moisture contents to lower limits. The ventilation system is closed loop system, which can be changeable to open system, and can be used as a multi-purposed dryer in which mixing, drying, granulating and cooling process is conducted. In order to develop non-gravity fluidized dryer, in the first the fundamental experiments performed to mixing accuracy and then the other parts of dryer and control system were examined to check whether they were designed properly and operated harmoniously with mixer. Also the preparatory experiments were fulfilled to examine the efficiency and reliability of dryer. Lastly, on the basis of preparatory experiments in case the initial moisture contents, desired moisture contents, heated air velocity and heating temperature were vary, performance test for the non-gravity fluidized dryer carried out.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.12 no.4
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• pp.263-269
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• 2012

The ability to characterize feature objects from radar readings is often limited by simply looking at their still frame reflectivity, differential reflectivity and differential phase data. In many cases, time-series study of these objects' reflectivity profile is required to properly characterize features objects of interest. This paper introduces a novel technique to automatically track multiple 3D radar structures in C,S-band in real-time using Doppler radar and profile their characteristic reflectivity distribution in time series. The extraction of reflectivity profile from different radar cluster structures is done in three stages: 1. static frame (zone-linkage) clustering, 2. dynamic frame (evolution-linkage) clustering and 3. characterization of clusters through time series profile of reflectivity distribution. The two clustering schemes proposed here are applied on composite multi-layers CAPPI (Constant Altitude Plan Position Indicator) radar data which covers altitude range of 0.25 to 10 km and an area spanning over hundreds of thousands $km^2$. Discrete numerical simulations show the validity of the proposed technique and that fast and accurate profiling of time series reflectivity distribution for deformable 3D radar structures is achievable.