• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.5
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• pp.62-70
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• 2007

In this paper, the boost Power Factor Correction(PFC) technique for Direct Torque Control(DTC) of brushless DC motor drive in the constant torque region is implemented on a TMS320F2812DSP. Unlike conventional six-step PWM current control, by properly selecting the inverter voltage space vectors of the two-phase conduction mode from a simple look-up table at a predefined sampling time, the desired quasi-square wave current is obtained, therefore a much faster torque response is achieved compared to conventional current control. Furthermore, to eliminate the low-frequency torque oscillations caused by the non-ideal trapezoidal shape of the actual back-EMF waveform of the BLDC motor, a pre-stored back-EMF versus position look-up table is designed. The duty cycle of the boost converter is determined by a control algorithm based on the input voltage, output voltage which is the dc-link of the BLDC motor drive, and inductor current using average current control method with input voltage feed-forward compensation during each sampling period of the drive system. With the emergence of high-speed digital signal processors(DSPs), both PFC and simple DTC algorithms can be executed during a single sampling period of the BLDC motor drive. In the proposed method, since no PWM algorithm is required for DTC or BLDC motor drive, only one PWM output for the boost converter with 80 kHz switching frequency is used in a TMS320F2812 DSP. The validity and effectiveness of the proposed DTC of BLDC motor drive scheme with PFC are verified through the experimental results. The test results verify that the proposed PFC for DTC of BLDC motor drive improves power factor considerably from 0.77 to as close as 0.9997 with and without load conditions.

• Journal of the Korea Society of Computer and Information
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• v.16 no.12
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• pp.285-296
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• 2011

UN, OECD, ITU and other international organizations regularly announce ISI (Information Society Index) to utilize in establishing and evaluating information policies. ISI is utilized as important data for countries to evaluate their information policy performance and select future projects. As the advancement of information systems, the importance of information security has been emerged. Accordingly, NISI (National Information Security Index) has been required. NISI number is the most clearly figure to express the characteristics of a particular group's information security. It can be utilized in determining information security policies. Currently, questionnaire method has been used to calculate NISI number. But there is an absolute lack of statistical data, and the reliability of surveyed statistical data is problematic. The objective of this paper is to show how to collect precise micro data of each company's information security index numbers, and to develop an OLAP database system which calculating NISI numbers by using those micro data. In this process of the survey, we presented the technique to collect the data more systematically, and to analyze the data without using questionnaire method. OLAP architecture performs only well on the facts that are summarizable along each dimension, where all hierarchy schemas are distributive. Therefore we transformed the non-distributive hierarchy schema into the distributive hierarchy schema to implement OLAP database system. It is thought that this approach will be useful one from an implementation and schema design point of view.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.91-101
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• 1996

In recent years, phytoremediation, the use of plants to detoxify hydrocarbons, has been a promising new area of research, particularly in situ cleanup of large volumes of slightly contaminated soils. There is increasing need for a mathematical model that can be used as a predictive tool prior to actual field implementation of such a relatively new technique. Although a number of models exist for solute-plant interaction in the vegetated zone of soil, most of them have focused on ionic nutrients and some metals. In this study, we developed a mathematical model for simulation of bioremediation of hydrocarbons in soil, associated with plant root systems. The proposed model includes root interactions with soil-water and hydrocarbons in time and space, as well as advective and dispersive transport in unsaturated soil. The developed model considers gas phase diffusion and liquid-gas mass exchanges. For simulation of temporal and spatial changes in root behavior on soil-water and with hydrocarbons, time-specific distribution of root quantity through soil was incorporated into the simulation model. Hydrocarbon absorption and subsequent uptake into roots with water were simulated with empirical equations. In addition, microbial activity in the rhizosphere, a zone of unique interaction between roots and soil microorganisms, was modeled using a biofilm theory. This mathematical model for understanding and predicting fate and transport of compound in plant-aided remediation will assist effective application of plant-aided remediation to field contamination.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.13-21
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• 2010

Road Traffic Authority and National Police Agency is currently managing the "development of an integrated metropolitan traffic information infrastructure" that installs of facilities for a traffic information infrastructures, such as Local Traffic Information Center, UTIS(Urban Traffic Information System), CCTV, VMS and etc. CTIC was established in 2005 to act as an traffic information hub and to provide integrated UTIS traffic information without regional barriers. This study was carried out to seek for solution to improve quality of UTIS traffic information service for the Central Traffic Information Center(CTIC). In this study, the Evaluation index for UTIS traffic information service was developed and the implementation plan was established by using requirement analysis method, case study and AHP(Analytic Hierarchy Process) technique. The Evaluation index consist of 5 fields and 20 index, it make possible evaluation of direct/indirect effect for UTIS traffic information service. In conclusion, It is expected that quality of UTIS traffic information service will be improved by using developed evaluation index and also can be applied for performance evaluation of other traffic information systems.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.4
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• pp.78-86
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• 1999

In this paper, a distributed arithmetic digital neural network with learning and testing phase implemented in a body has been studied. The proposed technique is based on the two facts; one is that the weighting coefficients adjusted will be stored in registers without shift, because input values or input patterns are not changed while learning and the other is that the input patterns stored in registers are not changed while testing. The proposed digital neural network is simulated by hardware description language such as VHDL and verified the performance that the neural network was applied to the recognition of seven-segment. To verify proposed neural networks, we compared the learning process of modified perceptron learning algorithm simulated by software with VHDL for 7-segment number recognizer. The results are as follows: There was a little difference in learning time and iteration numbers according to the input pattern, but generally the iteration numbers are 1000 to 10000 and the learning time is 4 to 200$\mu\textrm{s}$. So we knew that the operation of the neural network is learned in the same way with the learning of software simulation, and the proposed neural networks are properly operated. And also the implemented neural network can be built with less amounts of components compared with board system neural network.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.39-47
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• 2015

In this paper, we propose a new time synchronization algorithm using CoAP(constrained-application protocol) in sensor network environment, which handles a technique that synchronizes an explicit timestamp between sensor nodes not including an additional module for time-setting and sensor node gateway linked to internet time server. CoAP is a standard protocol for sensor data communication among sensor nodes and sensor node gateway to be built much less memory and power supply in constrained network surroundings including serious network jitter, packet losses, etc. We have supplied an exact time synchronization implementation among small and cheap IP-based sensor nodes or non-IP based sensor nodes and sensor node gateway in sensor network using CoAP message header's option extension. On behalf of conventional network time synchronization method, as our approach uses an exclusive protocol 'CoAP' in sensor network, it is not to become an additional burden for synchronization service to sensor nodes or sensor node gateway. This method has an average error about 2ms comparing to NTP service and offers a low-cost and robust network time synchronization algorithm.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.12
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• pp.73-82
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• 2008

There are several approaches for reducing the ROB(Reorder Buffer) complexity in processors. The one technique that makes the simplest ROB ports relies on a distributed implementation that spreads the centralized ROB structure across the functional units(FUs). Each distributed buffers are decided on the size of them by workload of the functional units. The performance of the processor depends on the size of distributed ROB. However, most of previous works have depended on the simulation results to decide the optimsize of distributed ROB. In this Paper, we use an analytical model based on the M/M/1 Queuing theory to determine the optimum size of each distributed ROB. Our schemes are evaluated by using the simulation performed by the CPU2000 benchmarks. We are able to choose the optimum size of distributed ROB showing the 99.2% performance compared with existing superscalar processors. We can save 82% hardware resources in ports and reduce more than 30% of delay when ROB and distributed ROB proposed in this paper are designed by HDL.

• 대한공업교육학회지
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• v.33 no.2
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• pp.137-153
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• 2008

This study has 4 purposes which are as the followings. First, it is to lay out the project based learning method which enables students to improve their creative skills. Second, it explains the appropriate way to apply the project based learning method to real learning situations. Third, it identifies how the students recognize the effectiveness of learning after the learning method has been applied. Finally, it discusses how learners recognized the effectiveness of project based learning method and how it enhanced their creative skills. During this study, research was conducted on students at J Industrial technical high school in a real learning situation. The study included 60 participants from 2 classes selected from 9 classes in third grade at the high school. Data was collected using surveys. Results indicated participants recognized the project based learning method allowed them to solve problems creatively. It enabled them to improve their creative skills and apply them to learning situation. Also, they recognized that this method provided them with varying creative thinking opportunities. The most effective technique to improve their creative skills was the brainstorming(42%), followed by creative problem solving(17%), and then the checklist method(15%). The content creation(32%), topic selection(32%), and project implementation(18%) for presentations best illustrated student originality.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.870-875
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• 2015

Diesel engines are widely used due to superior power and fuel consumption, however there are many challenges in exhaust gas management. Exhaust gas recirculation (EGR) is the most effective technique for reducing mono-nitrogen oxide (NOx) emissions in a diesel engine, in comparison with other catalytic technologies. In addition, the technology has a number of advantages in terms of economic efficiency and implementation. In this study, the effects on the power and exhaust characteristics of diesel engines equipped with EGR systems were investigated. It was found that as the EGR rate increased, horsepower expressed as IHP and BHP decreased. The net effect of the application of EGR was measured at various engine speeds. EGR technology caused decreases in BHP of around 9% during low engine speed and 3.5% during high engine speed. Additionally, NOx emissions reduced as the EGR rate increased, and increased as engine speed increased. However, smoke emissions increased as the EGR rate increased, and decreased as engine speed increased. The optimum operating conditions and ERG rate to simultaneously achieve minimum NOx and smoke emissions were investigate. It was found that as the EGR rate increased, optimal operating speed for minimal NOx and smoke also increased. Keywords: Diesel engine, Exhaust gas recirculation, Power perfomance, Emission characteristics, NOx, Smoke

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.2991-2999
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• 2013

Background: Introduction of the HPV vaccine is a forefront primary prevention method in reducing the incidence of carcinogenic human papillomavirus (HPV) and cervical cancer. The Malaysia government has implemented the National HPV immunisation programme since 2010, supplying HPV vaccine free to targeted 13 year olds. This study aimed to explore the level of knowledge among mothers on cervical cancer, HPV, HPV vaccine and National HPV (NHPV) immunisation programme since its' implementation. It also assessed acceptance of mothers towards HPV vaccine being administered to their daughter, son or themselves. Materials and Methods: A cross sectional study was conducted on 155 respondents using self-administered questionnaires; conducted in December 2012 at the Obstetrics and Gynaecology Clinic in a teaching hospital in Kuala Lumpur. Respondents were selected using a multistage sampling technique. Results: A response rate of 100% was obtained. Overall, 51.0% of mothers had good knowledge, with 55% having good knowledge of cervical cancer, 54.2% for both HPV and the National HPV immunisation programme and 51.0% for the HPV vaccine. Regression analyses showed that ethnicity was associated with knowledge on cervical cancer (p=0.003) while education was associated with knowledge on HPV (p=0.049). Three factors are associated with knowledge of the National HPV immunisation programme; ethnicity (p=0.017), mothers' education (p=0.0005) and number of children (p=0.020). The acceptance of HPV vaccine to be administered among daughter was the highest at 87.1%, followed by for mothers themselves at 73.5%, and the least is for sons 62.6%. Conclusions: This study found that the overall level of knowledge was moderate. Adequate information on cervical cancer, HPV, HPV vaccination and the National HPV immunisation programme should be provided to mothers in order to increase acceptance of the HPV vaccine which can reduce the disease burden in the future.