• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.10
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• pp.73-80
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• 1995

In this paper, a synthesis tool using matrix operations for designing multi-level Reed Muller circuits is described which has been named as MRM (Multi-level Reed Muller Minimizer). The synthesis method which uses matrix operations has advantages in effectively minimizing chip area, delay optimization and fault detection capability. However, it uses only truth-table type maps for inputs, synthesizing only small circuits. To overcome the weakness, our method accepts two-level description of a logic function. Since the number of cubes in the two-level description is small, the input matrix becomes small and large circuits can be synthesized. To convert two-level representations into multi-level ones, different input patterns are extracted to make a map which can be fed to the matrix operation procedure. Experimental results show better performance than previous methods. The matrix operation method presented in this paper is new to the society of Reed Muller circuits synthesis and provides solid mathematical foundations.

• Journal of Power Electronics
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• v.12 no.2
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• pp.285-293
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• 2012

Multilevel inverters have gained attention in high-power applications due to their numerous advantages in comparison with conventional two-level inverters. In this paper a simplified Space-Vector Modulation (SVM) algorithm for a three-level Neutral-Point Clamped (NPC) inverter is implemented on a Freescale$^{(R)}$ DSP56F8037. The algorithm is based on a simplification of the space-vector diagram for a three-level inverter so that it can be used with a two-level inverter. Once the simplification has been achieved, calculation of the dwell times and the switching sequences are carried out in the same way as for the two-level SVM method. Details of the hardware design are included. Experimental results are analyzed to validate the performance of the simplified algorithm.

• Journal of Power Electronics
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• v.14 no.5
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• pp.926-936
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• 2014

A simplified and effective space vector pulse-width modulation (SVPWM) algorithm with two and three levels for three-phase voltage-source converters is proposed in this study. The proposed SVPWM algorithm only uses several linear calculations on three-phase modulated voltages without any complicated trigonometric calculations adopted by conventional SVPWM. This simplified SVPWM also avoids choosing the vector sector required by conventional SVPWM. A two-level overmodulation scheme is integrated into the proposed two-level SVPMW to generate the output voltage that increases from a linear region to a six-step state with a smoothly linear transition characteristic and a simple overmodulation process without a lookup table and complicated nonlinear functions. The three-level SVPWM with a proportional-integral controller effectively balances the neutral point potential of the neutral point clamped converter. Results from the simulation in MATLAB/Simulink and the experiment based on a digital signal processor are provided to clearly demonstrate the validity and effectiveness of the proposed strategies.

• Journal of Korean Society of Transportation
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• v.9 no.1
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• pp.5-18
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• 1991

Two-Lane, two-way roads account for approximately 92% of total road length in Korea and accomplish the majority of regional transport activities. Nevertheless not too many research have been made on two-lane roads particularly efficiency related topics such as capacity and travel time studies. In this study a full scale data collection was conducted using video equippments on rural two-lane roads to determine capacity Passenger Car Equivalents(PCE) and Level of Service criterion. Various PC programs were utilized to reduce traffic data and Walker ME? and Headway Method were employed to determine PCE's for heavy vehicles. The reseach has shown that capacity and PCE's for two-land two-way roads in Korea are 3200 pcph and 1.1∼1.9 resectively. In addition percent time delay was used as the basis of developing Level of service criterion on two-lane roads in Korea.

• Journal of Power Electronics
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• v.9 no.5
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• pp.679-690
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• 2009

The paper presents a new photovoltaic inverter for stand-alone induction motor application. The proposed system is composed of two stages. First stage is for the photovoltaic dc power feeding and second stage is dedicated to the motor-inverter subsystem and control technique. A direct torque control (DTC) with a novel switching strategy for motor torque ripple minimization is introduced. The novel DTC strategy is based on selecting a suitable voltage vector group for motor torque ripple minimization. A three-level voltage source inverter (VSI) is used instead of a two level inverter because the first has more available vectors and lower ripples in the output current and flux than the second, thus it has lower torque ripples. The photovoltaic array and battery bank are sized and the configuration is indicated based on sun-hour methodology. Simulation results show a comparison between three systems; two level VSI with conventional DTC strategy, three level VSI with conventional DTC, and the proposed system that has a novel DTC switching strategy applied to three level VSI. The results show that the proposed system has lower ripples in the current, flux and torque of the motor.

• Korea journal of population studies
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• v.9 no.2
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• pp.30-41
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• 1986

It is worthwhile to compare the major social indicators between Korea the and Taiwan particularly focusing on population because two countries share close similarities in many aspects and gave access to the advanced level among the developing countries in recent years. Similarities or dissimilarities presented in this paper will be helpful to the researchers and the policy makers of the two countries by giving them insight on the situation. The similarities and dissimilarities between the two countries in the field of demography and social indicators are summarized as follows : 1. Similarity indicators can be found in fertility. One of them is Net Reproduction Rate and it was less than one in both countries in 1985. The past trend of fertility, in fact level and pattern of it, of the two countries from 1960 to 1985 has been very similar. 2. Level and pattern of mortality is quite different between two countries. Mortality level of Taiwan is lower than that of Korea. 3. The close similarity between two countries was shown in population structure and aging index. 4. On future population projection, the population structure and the level and pattern of fertility of the two countries are very similar. During fourty years, the period from the current population growth rate which is a little more than 1% to the zero growth rate, the annual population growth rate of the two countries is approximately 0.6% and that is similar to those of the current industrialized countries. According to the medium variant of the projection, Korean population will reach Zero Growth Rate between 2020 and 2025 whereas Taiwan between 2025 and 2020 5. Current level of contraceptive prevalence of both countries is very similar showing above 70% of the eligible women in 1985 and one of the valuable factors of achieving this high rate within short period must be the national program of the family planning. A close cooperation in the field of population policy formulation and its implementation is indispensable because Korea and Taiwan have similarity in many population indicators.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.4
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• pp.428-434
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• 1997

The effect of genetic diversity in sub-populations on breeding efficiency was examined with prospect of potential crossbreeding. Simulation study of selection was performed for 20 generations with 20 replications each, comparing average breeding values and inbreeding coefficients between the two breeding systemes; single population scheme and two population scheme. The different genetic levels were assumed to be caused by different gene frequencies. Phenotypes of two traits generated polygenic effect with additive 36 loci and residuals distributed normally were selected by selection index procedure. High genetic gain with less inbreeding was clearly recognized in the single population scheme, independently of difference in genetic level, economic weight and genetic correlation. Genetic correlation after selection in the single population scheme was lower than the two population scheme. When crossbreeding between the sub-population was taken into account, superiority of the two population scheme was suggested under those restrictions; difference in genetic level is moderate, selection criterion for the two traits is not far from even economic weight, and genetic correlation is positive with low to moderate value. The use of complementarity increased the possibility of the two population scheme.

• The Transactions of the Korea Information Processing Society
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• v.6 no.2
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• pp.467-475
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• 1999

This paper presents an algorithm for scheduling jobs in soft real-time systems. To simplify the scheduling for soft real-time systems, we introduce two-level deadline scheme. Each job in the system has two deadlines, which we call first-level and second-level deadlines, respectively. The first-level deadline is the same as the deadline in traditional real-time systems. The second-level deadline is later than the first-level deadline, and defines the latest point in time when the result is still acceptable. Partial-credit is given for jobs meeting the second-level deadline but missing the first-level deadline, whereas jobs meeting the latter are given full credit. We heuristically compute priorities of jobs in a dynamic way by combining the first-level adn second-level deadlines with the partial-credit. Simulation results indicate that our two-level scheduling algorithm is a viable approach for dealing with both soft real-time systems and temporary overloaded hard real-time systems.

• Journal of Korean Academy of Nursing
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• v.10 no.2
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• pp.41-52
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• 1980

As it Provides nursing students the opportunity for correlating principles and practice, clinical practice h s been considered as on of the most important part of nursing education. This study was desinged to measure the level of satisfaction in according with the conten. guidance environment. hours and the evaluation of clinical pracice. and to investigate the extent of influence of the variables have on the level of satisfaction. Two hundred and fifty-two nursing students from 9 baccalaureat programs in Seoule were randomly sampled. Instrument consists of forty questionaires. developed by the researcher, was used to gather data data from September 7 through 22, 1978. The level of satisfaction was measured by 5 Point rating scale(Likert-type). and level of significance were(t-test. F-test ＆ X$^2$-test). -Results are as follow; 1. Level of satisfation according to the four variables ( class health. academic achievement, motives) revealed no significant difference. (P>.05). Hypothesis 1,2,3,4, are rejected. 2. Level of satisfaction according to the two variables (clinical instructor interpersonal relationship) revealed significant difference. (p<.01, p<.05), Hypothesis 5,6 are accepted. 3. Level of satisfaction of contents (mean score=3.02) revealed to be high.. 4. Level of satisfaction on guidance (mean Score=2.37), environment (mean score=2.59), hours (mean score=2.72) and evaluation (mean score=2.50) revealed to be low. 5. Level of satisfaction revealed to be low. (total mean satisfaction score =2.64).

• ETRI Journal
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• v.34 no.4
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• pp.625-628
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• 2012

In this letter, a novel method for localizing a user in a smart home environment is presented. We propose a two-level structure, in which the first level determines an occupant's location in the block level using RSSI in a ZigBee network, while the second level accurately estimates the occupant's location using a particle filter to handle the variations in the signal strength measurement. We devise an experimental setup with people performing significant tasks in the smart home. The results obtained from the testbed indicate that the proposed model leads to an improvement in the mean distance error.