• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.13 no.5
• /
• pp.249-258
• /
• 2013

In multi-hop ad hoc networks, multi-interface multi-channel architecture is being noticing as methodology to improve the effective bandwidth and end-to-end throughput, But since existing routing metrics designed for networks based on single-interface exactly can not reflects the nature of networks based on multi-interface multi-channel, we are not expected the effect of throughput improvement. there had been proposal of MCR that discover high throughput by using metrics such as channel diversity and interface switching cost. however, MCR have an problem that is degraded it's performance in congested networks, because it not reflects the impact of traffic load. in this paper, we propose MAMCR metric, which select high throughput paths under congested conditions by combination MCR with channel access time metric, and conform it's the effect of performance improvement by ns-2 simulation.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.49 no.2
• /
• pp.134-142
• /
• 2012

This paper analyze an LDPC code replication method suitable for cloud computing. First, we determine the number of blocks suitable for cloud computing through analysis of the performance for the file availability and storage overhead. Also we determine the type of LDPC code appropriate for cloud computing through the performance for three types of LDPC codes. Finally we present the graph random generation method and the comparing method of each generated LDPC code's performance by the iterative decoding process. By the simulation, we confirmed the best graph's regularity is left-regular or least left-regular. Also, we confirmed the best graph's total number of edges are minimum value or near the minimum value.

• Journal of the Korean Society for Railway
• /
• v.20 no.4
• /
• pp.448-457
• /
• 2017

In this paper, for high speed railway propulsion systems, a single phase PWM Converter using discontinuous PWM (DPWM) was investigated. The conventional PWM Converter uses a low frequency modulation index of less than 10 to reduce switching losses due to high power characteristics, which results in low control frequency bandwidth and requires an additional compensation method. To solve these problems, the DPWM method, which is commonly used in three phase PWM Inverters, was adopted to a single phase PWM Converter. The proposed method was easily implemented using offset voltage techniques. Method can improve the control performance by doubling the frequency modulation index for the same switching loss, and can also bring the same dynamic characteristics among switches. Proposed DPWM method was verified by simulation of 100 kW PWM converter.

• Korean Journal of Clinical Pharmacy
• /
• v.21 no.4
• /
• pp.339-346
• /
• 2011

Over the past few decades, drug regulatory agencies in advanced countries have been emphasizing pharmacometrics as a tool for an effective and efficient drug evaluation. Despite this international movement, the value of pharmacometrics is still poorly recognized by the Korean drug evaluation system. This study aimed to analyze the current state of utilization of pharmacometrics by foreign drug regulatory agencies and develop a road map to guide the implementation pharmacometrics into the Korean drug evaluation system. MEDLINE and foreign drug regulatory agency database were extensively searched to obtain scientific research articles, guidance, regulations and pharmacometric review reports on foreign pharmacometric drug evaluation system. A systematic roadmap comprised of 3 stages to implement pharmacometrics in Korean drug evaluation system was formulated after analyzing the collected data in tune with the current evaluation system. Pharmacometrics is an urgently required tool to achieve an efficient drug evaluation and review in Korea. The road map developed by this study is expected to aid in setting up a policy to implement and utilize pharmacometrics in Korea.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.10
• /
• pp.1887-1894
• /
• 2016

In the RFID system, the reader transmits a query message to tags in order to identify a unique ID of tags within its detection range. The procedures for arbitrating a collision is essential because the multiple tags can response simultaneously in the same to the query of the Reader. This procedure is known as conflict resolution algorithm and it is a key technology in the RFID system. In this paper, we proposed a variable bits M-ary QT algorithm based on Manchester coding techniques. The proposed algorithm use the location information of the collision bits in the reader and tags. The proposed algorithm can reduce the number of the query-response cycle because it is capable of recognizing discontinuous bits and a variable number of bits. From computer simulation, the proposed method give better performance than the conventional M-ary QT techniques in terms of response, recognition efficiency, communication overhead.

• Proceedings of the SAREK Conference
• /
• 2008.11a
• /
• pp.611-617
• /
• 2008

Nowadays Plate Heat Exchanger (PHE) is widely used in different industries such as chemical, food and pharmaceutical process and refrigeration due to the efficient heat transfer performance, extreme compact design and efficient use of the construction material. In present study, discussed main conception of plate heat exchanger and applied in vacuum. PHE and aimed apply in the fresh water generator which installed in ship to desalinate seawater to fresh water use heat from engines. The experiment is proceeded to investigate the heat transfer between cold and hot fluid stream at different flow rate and supply temperature of hot fluid. Generated fresh water as outcome of the system. PHE is an important part of a condensing or evaporating system. One of common assumptions in basic heat exchanger design theory is that fluid is to be distributed uniformly at the inlet of each fluid side and throughout the core. However, in practice, flow mal-distribution is more common and can significantly reduce the heat exchanger performance. The flow and heat transfer are simulated by the k-$\varepsilon$ standard turbulence model. Moreover, the simulation contacted flow maldistribution in a PHE with 6 channels.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.5
• /
• pp.93-100
• /
• 2011

In this paper, we propose a FDR(False Data Reduction) strategy for P2P environment that reduces false data. The key idea of our strategy is that we use FDR algorithm to stop transmitting of false data and to delete that. If a user recognizes false data in downloaded-data and the user's peer requests the others to stop the transmission of the false data immediately. Also, the FDR algorithm notifies the other peers to prohibit spreading of the false data in the environment. All this procedure is possible to be executed in each peer without any lookup server. The FDR algorithm needs only a little data exchange among peers. Through simulation, we show that it is more effective to reduce the network traffic than the previous P2P strategy. We also show that the proposed strategy improves the performance of network compared to previous P2P strategy. As a result, The FDR strategy is decreased 9.78 ~ 16.84% of mean true data transmission time.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.8
• /
• pp.15-27
• /
• 2008

In this paper, an EBG(Electromagnetic BandGap) resonator antenna with a stripline type FSS(Frequency Selective Surface) superstrate for PCS-band base station antennas is proposed. The characteristics of resonant frequency and -3dB bandwidth of a unit cell of a superstrate are first analyzed by varing several design parameters such as a strip width and a unit cell width in order to design an EBG resonator antenna satisfying the required antenna gain and bandwidth for PCS-band base station antennas. Among various unit cell shapes, strip dipole and stripline are considered and their characteristics are compared. It was found that a resonant length of the EBG resonator antenna becomes smaller when the stripline shape is used and the control of the bandwidth is also much easier. By using the unit cell simulation results, planar and cylindrical EBG resonator antennas at PCS-band are designed.

• Journal of the Society of Naval Architects of Korea
• /
• v.52 no.2
• /
• pp.97-103
• /
• 2015

This paper has focused on the middle term process planning around quays based on the prefixed long-term plan of the product mixed ships. Recently, the order rate of high add-value ships in domestic shipyards has been sharply increased and the spending time at quays is accordingly on an increasing trend. For proper and practical process planning related to quays, it has to be closely connected with a long-term plan and product calendar, erection network and result of ship allocation around quays. Moreover, it is also required to include the integrated consideration of the whole process of a yard, each ship, and each team respectively. The most distinguishing feature of this study is that it would run on the ship allocation simulator and GIS framework in order not to be limited to the specific one yard and the readers can figure out the optimization formulation containing the work load leveling and a different approach from PERT/CPM. The proposed approach reflected all requirements from the department of process planning and management in a shipyard, and the analysis of the results has explained its performance of the optimization result with the examples of total 43 ships under construction from 2008 to 2013.

• Magazine of the Korea Concrete Institute
• /
• v.20 no.6
• /
• pp.28-35
• /
• 2008

The Burj Dubai Project will be the tallest structure ever built by man; when completed the tower will be more than 700 meter tall and more than 160 floors. While the early integration of aerodynamic shaping and wind engineering considerations played a major role in the architectural massing and design of this multi-use/residential tower, where mitigating and taming the dynamic wind effects was one of the most important design criteria, the material selection for the structural systems of the tower was also a major consideration and required detailed evaluation of the material technologies and skilled labor available in the market at the time Concrete was selected for its strength, stiffness, damping, redundancy, moldability, free fireproofing, speed of construction, and cost effectiveness. In addition, the design challenges of using concrete for the design of the structural system components will be addressed. The focus on this paper will also be on the early planning of the concrete works of the Burj Dubai Project.