• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.13 no.2
• /
• pp.143-148
• /
• 2013

This paper study about multi-beam for ditection of arrival estimation in wireless system. estimate a direction of arrival of target in multi input-output array antennas system. Beam steering method are divided by beam steering method of elevation angle or beam forming method, stack beam steering, frequency steering, phase steering radar and digital beam forming radar. Proposed algorithm is combined SVD method and antenna weight error compensation method with phase and amplitude compensation to effectivity beam steering. Through simulation, we were analysis of performance that general algorithm and proposed target estimation algorithm in this paper. It was proved to improved proposal algorithm than general algorithm in target direction of arrival estimation.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.7
• /
• pp.30-36
• /
• 2011

Three-dimensional (3D) memories using through-silicon vias (TSVs) as vertical bus across memory layers are implemented by many semiconductor companies. 3D memories are composed of known-good-dies (KGDs). If additional faults are arisen during bonding, they should be repaired. In order to enhance the yield of 3D memories with inter-die redundancies, a die-matching method is needed to effectively stack memory dies in a 3D memory. In this paper, a new die-matching method is proposed for 3D memory yield enhancement with inter-die redundancies considering additional faults arisen during bonding. Three boundary-limited conditions are used in the proposed die-matching method; they set bounds to the search spaces for selecting memory dies to manufacture a 3D memory. Simulation results show that the proposed die-matching method can greatly enhance the 3D memory yield.

• Fire Science and Engineering
• /
• v.26 no.2
• /
• pp.90-96
• /
• 2012

Since vertical flame spread speed on exterior materials is much faster than horizontal fire, analysis of its fire characteristic is required. For the study of vertical fire pattern created by penetrating windows or openings from the exterior wall of buildings, the research is based on the fire simulation for an aluminum-complex-panel with which is commonly used as exterior materials and consists of polyethylene core material. As a result, the flame reaches the 2nd floor after 135 seconds in the early stage of fire, the 10the floor after 470 seconds and the 30th floor, the highest floor, after 711 seconds. The result shows that fire spread abruptly expands on upper floor due to stack effect of a turbulent flow or exterior materials. In consequence, we can confirm a serious problem that a conflagration of a building through an opening that is equipped with the exterior-materials spreads into interior of building at that same time.

• Journal of KIISE:Information Networking
• /
• v.31 no.3
• /
• pp.314-326
• /
• 2004

Bluetooth has been reputed as a wireless ad-hoc networking technology supplying scalable and extensible networks between digital devices. For that kind of networks, scatternet is a most essential part in bluetooth. But past researches on bluetooth scatternet has proposed only possibilities of scatternet algorithm based on simulation results. And many of the researches failed in guaranteeing extensibility and flexibility and had many difficulties in real hardware implementation. In this paper, we proposed node ring scatternet(NRS) algorithm guaranteeing extensible and flexible networks. NRS algorithm is designed for hardware implementation using real commercial bluetooth module. That algorithm is divided into initial formation and reformation. For initial formation, we proposed limited SEEK/SCAN algorithm. For reformation, we proposed DIAC algorithm and Reserved Recovery Node algorithm. And we proposed SFMP(Scatternet Formation ＆ Management Protocol) in protocol stack for real implementation. NRS algorithm is operated in SFMP. Finally, we performed real hardware experiments and evaluated the proposed algorithm. In that experiments, we succeeded in forming scatternet up to 20 nodes. In comparison with other similar algorithm, proposed algorithm have the improvement in scatternet formation delay and success rate.

• Fire Science and Engineering
• /
• v.30 no.1
• /
• pp.6-11
• /
• 2016

This study analyzed the performance of smoke exhaustion installed to secure the life safety from the smoke each opening modes, as performing the simulation on the Jeju regions generating to strong windy using CONTAM. We assessed the effectiveness of the system under conditions of high external winds as well as an ambient wind conditions. It also assessed the relative effectiveness of opening all vents versus opening only those vents which served rooms in which the fire was located. This study revealed external winds exerted a substantial impact on the performance of the smoke ventilation system. It was found that opening the ventilation system in the room containing the fire resulted in a greater performance than opening vents in both fire in all rooms. The reduced performance of the smoke ventilation system upon the opening of all vents is thought to be due to the intrusion of outside air, and the establishment of unfavorable air circulation, caused by the negative pressure generated in the building.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.6B
• /
• pp.575-583
• /
• 2004

In this paper, we extend the multiple time scale control framework to the window-based congestion control, in particular, such as the TCP. This is performed by interfacing the TCP with a large time scale control module which adjusts the aggressiveness of the bandwidth consumption behavior exhibited by the TCP as a function of large time scale Self-Similar network state. i.e., conformation that exceeds the horizon of the feedback loop as determined by the RTT. How to effectively utilize such an information-due to its probabilistic nature, dispersion over the multiple time scales, and affection on the top of the existing window-based congestion controls-is a non-trivial problem. The evaluation performance of the multiple time scale TCP is facilitated by a simulation of the bench-mark environment which is based on the physical modeling of a self-similar traffic. We explicate our methodology for discerning and evaluating the impact of changes in transport protocols in the protocol stack under the self-similar traffic conditions. We discuss issues arising in the comparative performance evaluation under heavy-tailed workloads.

• The Journal of the Convergence on Culture Technology
• /
• v.6 no.1
• /
• pp.495-500
• /
• 2020

VANET (Vehicular Ad Hoc Network), an example of an ad hoc vehicular networks, becomes one of the popular research areas together with the self-driving cars and the connected cars. In terms of the VANET implementation, the traditional TCP/IP protocol stack could be applied to VANET. Recently, CCN (Content Centric Networking) shows better possibility to apply to VANET, called VCCN (VANET over CCN). CCN maintains several data tables including CS (Content Store) which keeps track of the currently requested content segments. When the CS becomes full and new content should be stored in CS, a replacement algorithm is needed. This paper compares and contrasts four replacement algorithms. In addition, it analyzes the transmission characteristics in diverse network conditions. According to the simulation results, LRU replacement algorithm shows better performances than the remaining three algorithms. In addition, even the size of CS is small, the network maintains a reasonable transmission performance. As the CS size becomes larger, the transmission rate increases proportionally. The transmission performance decreases when the network is crowded as well as the number of transmission hops becomes large.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.8
• /
• pp.52-58
• /
• 2008

Ths paper describes the Dual-band switch which was proposed new structure that could improved the specification of broadband and designed by the optimized structure through simulation. The Dual-band switch with 2.4[GHz]/5.8[GHz] that can apply to 802.11a/b/g system that is commercialized present was studied to get a new structure with higher power, high isolation. The transmitter of switch was designed to operate a parallel switching element with stack structure of two FET. The receiver designed to have asymmetry structure that insert series FET in addition to basic serial/parallel FET. SPDT(Single Pole Double Throw) Tx/Rx FET switch is a device that can do switching from a port of input to two port of output. The fabricated SPDT switch has the characteristic of insertion loss of a below -3[dB] form DC to 6[GHz] and the isolation of a below -30D[dB](Rx mode).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.3
• /
• pp.465-469
• /
• 2019

In this paper, the design of BLDC (brushless direct current) motors based on torque and back-EMF equations was carried out to assess the application of the motor in concrete vibrators. The air gap flux density of the motor is an important parameter because the length of the motor and the size of the diameter are given. The air gap magnetic flux density was calculated through a simplified magnetic circuit, and basic design of the shape and dimensions of the motor were then determined by carrying out experiments based on torque, back-EMF, and air magnetic flux density equations. After setting the outer and inner diameters, stack lengths, and rated speed of the motor, a detailed design was performed by simulations using the finite element method by designating the diameter and thickness of the motor as the key parameters. The final design to satisfy the target torque and the lowest THD (Total Harmonic Distortion) was carried out along with a simulation.

• Clean Technology
• /
• v.24 no.4
• /
• pp.357-364
• /
• 2018

Studies on the production of biogas from third generation biomass, such as micro- and macroalgae, have been conducted through experiments of various scales. In this paper, we investigated the feasibility of commercialization of integrated combined heat and power (CHP) production using biogas derived from macroalgae, i.e., seaweed biomass. For this purpose, an integrated CHP plant of industrial scale, consisting of solid oxide fuel cells, gas turbine and organic Rankine cycle, was designed and simulated using a commercial process simulator. The cost of each equipment in the plant was estimated through the calculated heat and mass balances from simulation and then the techno-economic analysis was performed. The designed integrated CHP process produces 68.4 MW of power using $36ton\;h^{-1}$ of biogas from $62.5ton\;h^{-1}$ (dry basis) of brown algae. Based on these results, various scenarios were evaluated economically and the levelized electricity cost (LEC) was calculated. When the lifetime of SOFC is 5 years and its stack price is $$225kW^{-1}$, the LEC was 12.26 ¢ $kWh^{-1}$, which is comparable to the conventional fixed power generation.