• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12B
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• pp.1749-1757
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• 2010

This paper considers the cost minimization problem to satisfy QoS (Quality of Service) requirements for a given network, in particular when communication resources to each link can be additionally assigned. For the purpose of quantifying QoS requirements such as data transfer delay and packet loss, we introduce the cost function considering both the link utilization factor and the additionally assigned resource. To minimize this cost function, we firstly formulate a Basic Capacity Planning (BCP) problem, a special case of Network Utility Maximization (NUM). We show that the solution of this BCP problem cannot be optimal via a counter example. In this paper, we suggest the cross-layer design of both additionally assigned resource and routing path, whose initial values are set to the result of BCP problem. This cross-layer design is based on a heuristic approach which presents an effective way to plan how much communication resources should be added to support the QoS requirements in future. By simulation study, we investigate the convergence of the cost function in a more general network topology as well as in a given simple topology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.279-285
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• 2017

The study on 'support for V2V(Vehicle to Vehicle) services based on LTE sidelink' has been carried out in 3GPP RAN working group. The conventional LTE sidelink technology is not adequate for high speed V2V communications because the conventional DM-RS(Demodulation Reference signal) structure is developed for pedestrian environment. While the typical speed of pedestrian environment is 3km/h, that of V2V communications is 120 km/h and the information on channel estimation is not sufficient with legacy DM-RS structure. In this paper, improved DM-RS structures for V2V communications that have rapid channel variation are introduced and the performance of channel estimation accuracy is analyzed. Simulation results show that the performance improvement of channel estimation can be achieved based on extended sub-carrier spacing structure resulted from reduced inter-carrier interference. However, the extended sub-carrier spacing requires the longer cyclic prefix and higher overhead. As a results of considerations on DM-RS modification, the sub-carrier spacing is maintained and the high density of DM-RS is applied for V2V communications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.10-18
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• 2014

In this paper, we propose a new frequency reconfigurable dual-band antenna. By using an electronically compact eighth-mode substrate-integrated-waveguide(EMSIW) resonator, we have designed a compact antenna, which performs dual-band movement by additionally loading a complementary split ring resonator(CSRR) structure. The EMSIW and CSRR structures are designed to satisfy the bandwidths of 1.575 GHz(GPS) and 2.4 GHz(WLAN), respectively. We load the CSRR with a varactor diode to allow a narrow bandwidth and to enable the resonance frequency to continuously vary from 2.4 GHz to 2.5 GHz. Thus, we realize a channel selection function that is used in the WLAN standards. Irrespective of how a varactor diode moves, the EMSIW independently resonates so that the antenna maintains a fixed frequency of the GPS bandwidth even at different voltages. Consequently, as the DC bias voltage changes from 11.4 V to 30 V, the resonance frequency of the WLAN bandwidth continuously changes between 2.38 GHz and 2.5 GHz, when the DC bias voltage changes from 11.4 V to 30 V. We observe that the simulated and the measured S-parameter values and radiation patterns are in good agreement with each other.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.3
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• pp.173-181
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• 2007

A three-dimensional ecological model (EMT-3D) was applied to Tokyo Bay for the simulation of PFOA. EMT-3D was calibrated with seawater analysis data obtained from the study area in 2004. The simulated results of dissolved PFOA were in good agreement with the observed values, with a correlation coefficient(R) of 0.7115${\sim}$0.8759 and a coefficient of determination $(R^2)$ of 0.5062${\sim}$0.7672. The results of sensitivity analysis showed that partition rate, adsorption rate and settling rate were important factors for PFOA in particulate organic matter. In the case of PFOA in phytoplankton, bioconcentration factor, uptake rate and partition rate were important factors. Therefore, the parameters must be carefully considered in the modeling. In the case of 50% and 80% total loads reduction, concentration of dissolved PFOA was shown to be lower than 20ng/L and 10ng/L, respectively. In the case of reduction of loads from rivers in each prefecture, Tokyo prefecture was found to have the most influence on the change of dissolved PFOA in surface water while Chiba prefecture was found to have the most influnce on the change of dissolved PFOA in bottom water.

• Journal of Digital Contents Society
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• v.17 no.5
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• pp.307-316
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• 2016

A user usually gets the same suggesting results as everyone else in most of the multimedia social services, nowadays. To address the challenging problem of personalization in the social network, we propose a method which exploits user's activities, user's moods, and user's friend relationships from the social network to build a decision-making system. Depending on a current state of the user's mood, this system infers the most appropriated video for the user. In the system, the user evaluates a set of the given recommendation methods which extract from the user's database social network and assigns a vague value to each method by a weight. Then, we find the fuzzy collection solution for the system and classify the set of methods into subsets, and order the subsets based on its local dominance to choose the best appropriate method. Finally, we conduct an experiment using the YouTube API with a lot of video types. The experiment result shows that the channel recommendation system appropriately affords the user's character, it is more satisfying than the current YouTube based on an evaluation of several users.

• Food Science of Animal Resources
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• v.32 no.1
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• pp.91-97
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• 2012

Antimicrobial resistance of foodborne pathogens is an important food safety issue worldwide as well as in Korea. In this study, exposure to antimicrobial resistant (AMR) Stapylococcus aureus was assessed from the consumption of pork based food dishes prepared in food service operations using the Monte Carlo simulation. Thirty five isolates of S. aureus were obtained from 124 semi-processed pork products and their antibiotic resistance patterns were determined. The highest resistance was observed for penicillin (76.7%) followed by ampicillin (70.0%). Two isolates were resistant to oxacillin (6.7%) and no vancomycin resistance was observed. Dietary exposure to penicillin resistant S. aureus as the most frequently observed AMR S. aureus from pork-based dishes was estimated based on contamination data as well as compliance to guidelines for time and temperature controls during food service operations. The mean level of penicillin resistant S. aureus in pork dishes during preparation was below 1 Log CFU/g. As a conservative approach, 95th percentile estimated level of penicillin resistant S. aureus was below the level for toxin production. The estimated probability of staphylococcal intoxication by AMR S. aureus was very low using currently available data.

• Geophysics and Geophysical Exploration
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• v.12 no.4
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• pp.347-354
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• 2009

Physical properties of rocks are strongly dependant on details of pore micro-structures, which can be used for quantifying relations between physical properties of rocks through pore-scale simulation techniques. Recently, high-resolution scan techniques, such as X-ray microtomography and high performance computers make it possible to calculate permeability from pore micro-structures of rocks. We try to extend this simulation methodology to velocity and electrical conductivity. However, the smoothing effect during tomographic inversion creates artifacts in pore micro-structures and causes inaccurate property estimation. To mitigate this artifact, we tried to use sharpening filter and neural network classification techniques. Both methods gave noticeable improvement in pore structure imaging and accurate estimation of permeability and electrical conductivity, which implies that our method effectively removes the smoothing effect in pore structures. However, the calculated velocities showed only incremental improvement. By comparison between thin section images and tomogram, we found that our resolution is not high enough, and it is mainly responsible for the inaccuracy in velocity despite the successful removal of the smoothing effect. In conclusion, our methods can be very useful for pore-scale modeling, since it can create accurate pore structure without the smoothing effect. For accurate velocity estimation, the resolution of pore structure should be at least three times higher than that for permeability simulation.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.3
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• pp.57-63
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• 2002

This paper describes a control algorithm for the buffer of a deep-sea mining system, in which the buffer is connected to a long slender pipe and then to a surface ship on one end, and to a collector on sea floor through a flexible hose on the other end. A mathematical modeling is established for designing the controller for buffer thrusters, in which the dynamic response of the long pipe is taken into account based on the mode superposition method. The fluid loading acting on the pipe is estimated by using Morison's formula. For simplicity, the surface ship is assumed to be kept stationary, the reaction from the flexible hose is ignored and only the lateral motions are considered. In order to guide the buffer to react only to the low-frequency motion of the surface vessel, the FIR digital filter is introduced to a PID-based controller It can be shown numerically that the high frequency component of the ship's motion can be effectively filtered out by using the FIR low pass filter.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.3
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• pp.70-78
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• 2000

In this study, a new method for canceling MRI artifacts through the motion translation of image plane is presented Breathing often makes problems in a clinical diagnosis. Assuming that the head moves up and down due to breathing, rigid translational motions in only y(phase encoding axis) direction are treated Unlike the conventional Iterative phase retrieval algorithm, this method is based on the MRI imaging process and analyzing of Image property A new constraint condition with which the motion component and the true image component in the MRI signal can be separated by a simple algebraic operation is extracted After the x(read out) directional Fourier transformation of MRI signal is done, the y(phase encoding) directional spectrum phasing value is Just an algebraic sum of the Image component and the motion component Meanwhile, as It is known that the density of subcutaneous fat area is almost uniform in the head tomographs, the density distribution along a y directional line on this fat area is regarded as symmetric shape If the density function is symmetric, then the phase of spectrum changes linearly with the position Hence, the departure component from the linear function can be separated as the motion component Based on this constrant condition, the new method of artifact cancellation is presented Finally, the effectiveness of this algorithm IS shown by using a phantom with simulated motions.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.1
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• pp.59-67
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• 2016

A novel instrumentation amplifier (IA) using fully-differential linear operational transconductance amplifier (FLOTA) for electronic measurement systems with low cost, wideband, and gain control with wide range is designed. The IA consists of a FLOTA, two resistor, and an operational amplifier(op-amp). The principal of the operating is that the difference of two input voltages applied into FLOTA converts into two same difference currents, and then these current drive resistor of (+) terminal and feedback resistor of op-amp to obtain output voltage. To verify operating principal of the IA, we designed the FLOTA and realized the IA used commercial op-amp LF356. Simulation results show that the FLOTA has linearity error of 0.1% and offset current of 2.1uA at input dynamic range ${\pm}3.0V$. The IA had wide gain range from -20dB to 60dB by variation of only one resistor and -3dB frequency for the 60dB was 10MHz. The proposed IA also has merits without matching of external resistor and controllable offset voltage using the other resistor. The power dissipation of the IA is 105mW at supply voltage of ${\pm}5V$.