• Journal of KIISE:Computer Systems and Theory
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• v.27 no.7
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• pp.665-674
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• 2000

In data parallel programs incurring high cache locality, the choice of grain sizes affects cache performance. Though the grain sizes chosen provide fair load balance among processors, the grain sizes that ignore underlying caching effect result in address interferences between grains allocated to a processor. These address interferences appear to have a negative impact on the cache locality, since they result in cache conflict misses. To address this problem, we propose a best grain size driven from a cache size and the number of processors based on direct mapped cache's characteristic. Since the proposed method does not map the grains to the same location in the cache, cache conflict misses are reduced. Simulation results show that the proposed best grain size substantially improves the performance of tested data parallel programs through the reduction of cache misses on direct-mapped caches.

• Composites Research
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• v.27 no.2
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• pp.59-65
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• 2014

Most of energy are obtained from oil, coal, and natural gas, most likely, fossil fuel which is limited throughout the world. Recently, high crude oil price, climate change, oil depletion, etc. are main reason to get attention to non-fossil energy including renewable energy in the world. In this study, we studied analysis and design of structure system composed of pultruded fiber reinforced polymer composite (PFRP) which has many advantages such as high specific strength and stiffness, high corrosion resistance and chemical resistance. For the design and construction of floating-type structure, PFRP structural members may be the first choice. Design of tracking-type floating PV generation structure was performed by using the results of the finite element analysis. The structure is fabricated and installed on the water surface. Before the installation of the structure, safety related problems associated with installation and operation are investigated using the finite element simulation and it was found that the structure is safe enough to resist externally applied loads.

• Journal of Korean Society of Rural Planning
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• v.16 no.3
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• pp.143-157
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• 2010

This study provides a physical indicator of landscape that can be guidelines so as to evaluate landscape agricultural region for visual landscape planning, finds out the guideline for visual landscape planning lastly through examining importance of indicators and the preference of each indicator of landscape. The physical landscape indicators were derived from document study and questionnaire survey to evaluate visual landscape on landscape agricultural region. In addition, field study was conducted to examine and inspect the physical landscape indicator, managers' interview and photograph was took for evaluating the landscape simulation. Moreover, the important elements for visual landscape planning of landscape agricultural region, the importance of physical landscape indicator and the preferences of each indicator were derived by conducting questionnaire to experts and general publics. The physical landscape indicator guideline was established from the following procedures. In case of the land, flat area had higher preference than steep region. So, planning an agricultural area at a flat region with open space will be better than establishing an agricultural area on a steep region. In case of the kind of landscape crops, For the background of landscape agricultural region, the seashore type had the highest preference and mountain type and non-background type was followed in order. According to the study, facilities built with natural elements such as straw-roofed pavilion received high preference. Therefore, look-out shed and straw-roofed pavilion should be introduced in the landscape agriculture planning to select materials and colors to keep harmony with the nature. The result of this study could be used as a best choice for improving visual landscape of landscape agricultural region on selecting suitable land, facilities and so on. Moreover, the results of manager interview could be used as a useful tool in the management and formation of visual landscape. The landscape point evaluating visual landscape of landscape agricultural region could be used as a reference for establishing relative guideline for the direct payment program for rural landscape conservation and landscape agreement. In addition, it could be a useful reference to improve the general landscape and revitalize the rural area.

• The Korean Journal of Emergency Medical Services
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• v.7 no.1
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• pp.109-118
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• 2003

With the rapid development of information and communication technology, a lot of multi-media learning programs are being developed and reported in the field of Emergency medicine both home and abroad. In this connection, this study was aimed at developing a foreign-body airway obstruction courseware in adults for EMT. The development period of CAI courseware lasted from May 2003 through November 2003. Among CAI courseware patterns, private instruction and repeat practice and simulation patterns were used as an instruction-learning strategy. The learning contents of the CAI courseware consisted of five chapters concerning (1) A relief of partial FBAO in the responsible victim, (2) A relief of complete FBAO in the responsible victim, (3) In case of unconsciousness in the responsible victim without removing all foreign body, (4) In case of consciousness in all victims after getting removed all foreign body and (5) A complete airway obstruction in victims without consciousness on the basis of assess responsiveness and the degree of airway obstruction. The way to use this courseware, with just a click on one specific chapter, was developed to proceed a course with progressive algorithm, a method of solving problems by choosing one between two situations. A characteristic of this CAI courseware is the enhanced efficiency of an instruction-learning method by providing an opportunity of choice based on situations in its effort to encourage learners to use a self-initiated learning method, not one-way method and to enhance problem solving skills among situations. Moreover, this courseware went through the diverse phases such as development, application, feedback in connection with learning process by practicing teachers, so that the courseware could be used frequently in the future. The contents of this courseware were written with the web, so that, if necessary, the contents could be continuously modified and complemented and handed out in the form of CD-ROM. This study indicates that the development of a variety of CAI courseware requires institutional and financial assistance and initiatives reflecting a reality in terms of learning process, technical assistance and resources.

• Tunnel and Underground Space
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• v.12 no.1
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• pp.19-30
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• 2002

Rock joint orientation is one of important geometric attributes that have an influence on the stability of rock structures such as rock slopes and tunnels. Especially, statistical models of the geometric attributes of rock joints can provide a probabilistic approach of rock engineering problems. The result from probabilistic modeling relies on the choice of statistical model. Therefore, it is critical to define a representative statistical model for joint orientation data as well as joint size and intensity and build up a series of modeling procedure including analytical validation. In this paper, we have examined a theoretical methodology for the statistical estimate and hypothesis analysis based upon Fisher distribution and bivariate normal distribution. In addition, we have proposed the algorithms of random number generator which is applied to the simulation of rock joint networks and risk analysis.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2018-2030
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• 2015

A two stage ac drive configuration consisting of a single-phase line commutated rectifier and a three-phase voltage source inverter (VSI) is very common in low and medium power applications. The deterministic pulse width modulation (PWM) methods like sinusoidal PWM (SPWM) could not be considered as an ideal choice for modern drives since they result mechanical vibration and acoustic noise, and limit the application scope. This is due to the incapability of the deterministic PWM strategies in sprawling the harmonic power. The random PWM (RPWM) approaches could solve this issue by creating continuous harmonic profile instead of discrete clusters of dominant harmonics. Insufficient filtering at dc link results in the amplitude distortion of the input dc voltage to the VSI and has the most significant impact on the spectral errors (difference between theoretical and practical spectra). It is obvious that the sprawling effect of RPWM undoubtedly influenced by input fluctuation and the discrete harmonic clusters may reappear. The influence of dc link fluctuation on harmonics and their spreading effect in the VSI remains invalidated. A case study is done with four different filter capacitor values in this paper and results are compared with the constant dc input operation. This paper also proposes an ingenious RPWM, a ripple dosed sinusoidal reference-random carrier PWM (RDSRRCPWM), which has the innate capacity of suppressing the effect of input fluctuation in the output than the other modern PWM methods. MATLAB based simulation study reveals the fundamental component, total harmonic distortion (THD) and harmonic spread factor (HSF) for various modulation indices. The non-ideal dc link is managed well with the developed RDSRRCPWM applied to the VSI and tested in a proto type VSI using the field programmable gate array (FPGA).

• Computers and Concrete
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• v.18 no.5
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• pp.1041-1051
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• 2016

In this study, the construction of a reinforced concrete bridge pier was analyzed from durability point of view. The goal of the study is to analyze the crack iniation condition due to construction and present some recommendations for construction conditions of the reinforced concrete bridge pier. The bridge is located at the western port area of Shenzhen, where the climate is high temperature and humidity. To control the cracking of concrete, a construction simulation was carried out for a heat transfer problem as well as a thermal stress problem. A shrinkage model for heat produced due to cement hydration and a Burger constitutive model to simulate the creep effect are used. The modelling based on Femmasse(C) is verified by comparing with the testing results of a real underground abutment. For the bridge pier, the temperature and stress distribution, as well as their evolution with time are shown. To simulate the construction condition, four initial concrete temperatures ($5^{\circ}C$, $10^{\circ}C$, $15^{\circ}C$, $20^{\circ}C$) and three demoulding time tips (48h, 72h, 96h) are investigated. From the results, it is concluded that a high initial concrete temperature could result in a high extreme internal temperature, which causes the early peak temperature and the larger principle stresses. The demoulding time seems to be less important for the chosen study cases. Currently used 72 hours in the construction practice may be a reasonable choice.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.5
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• pp.405-412
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• 2015

This paper represents a filter design to estimate the airspeed of a spin-stabilized, trajectory-correctible artillery ammunition. Due to the limited power and space in operational point of view, the airspeed sensor is not installed, and thus the airspeed need to be estimated using limited sensor measurements. The only IMU measurements(three-axis specific forces and angular rates) are used in this application. The extended Kalman filter algorithm is applied since a linear filter can not cover the its wide operational range in airspeed and altitude. In the implementation of the EKF, the state and measurement equations are transformed into the no-roll frame for simple form of Jacobian matrix. The simulation study is conducted to evaluate the performance of the filter under various environment conditions of sensor noise and wind turbulence. In addition, the effect of the choice in filter design parameters, i.e. process error covariance matrices is analyzed on the performance of the estimation of airspeed and angular rates.

• Journal of Korea Multimedia Society
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• v.4 no.4
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• pp.333-338
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• 2001

In this paper, fuzzy-ARTMAP equalizer is developed mainly for overcoming the obstacles, such as complexity and long training, in implementing the previously developed neural-basis equalizers. The proposed fuzzy-ARTMAP equalizer is fast and easy to train and includes capabilities not found in other neural network approaches a small number of parameters, no requirements for the choice of initial weights, no risk of getting trapped in local minima, and capability of adding new data without retraining previously trained data. In simulation studies, binary signals were generated at random from linear channel with Gaussian noise. The performance of the proposed equalizer is compared with other neural net basis equalizers, such as MLP and RBF equalizers. The fuzzy ARTMAP equalizer combines relatively simple structure and fast processing speed; it gives accurate results for nonlinear problems that cannot be solved with a linear equalizer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5A
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• pp.493-500
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• 2006

This paper presents the efficient structure and parameter optimization of downlink beamforming transmitter in OFDMA/TDD system. To design downlink beamforming transmitter for multiple transmit antennas, an efficient beamforming structure for multiple users and the choice of word-length of each block are critical in the aspect of its performance and hardware complexity. We propose an efficient beamforming scheme, which stores the weights of subcarriers into memory without user identification at the receiver of base station and calculates the weights for corresponding user in a subcarrier unit of IFFT input at high speed. Also, we obtain the word-length of main data path and other design parameters by fixed-point simulation analysis. The proposed architecture could reduce the memory size proportional to the maximum number of users per frame, and the processing time of an OFDM symbol at the receiver of base station without the need of additional processing time for calculating the weights at the transmitter.