• Survey Research
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• v.12 no.1
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• pp.153-174
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• 2011

This research aims to discuss the causes of inaccuracy in public opinion polls currently conducted in Korea. In particular, identifying the problems in sampling frame and sampling methods in political and social public opinion polls is an important question. Currently, most polling organizations operating in Korea are using phone number directories provided by Korea Telecom(KT) as its sampling frame for conducting most political polls. A critical problem of using a phone number directory as a sampling frame is that unlisted phone numbers can never be included in the sample. If a systematic difference in socio-demographic or politico-economic characteristics exists between the listed number using group and the unlisted group, using a phone number directory as a sampling frame cannot produce a sample that can represent the whole adult population in Korea. According to the poll result commissioned by the Asan Institute for Policy Studies in January 2011, there are statistically significant differences in socio-demographic and politico-economic characteristics between those two groups, and those differences led to the differences in the presidential job approval rating and party support. Our findings include that the listed number using group is more pro-Grand National Party and show stronger support for the president than the unlisted group.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.1
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• pp.150-158
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• 2010

Filtering is necessary for the SRC(sample rate converter), that is used to change the sampling rate of a digital signal. The larger the conversion ratio of the sampling rate becomes, the more signal processing is needed for the filter, which means more complexity on realization. Thus it is important to reduce the amount of signal processing for the case of substantial conversion ratios. In this paper it is presented an efficient design method of a multistage FIR(finite impulse response) filter, with which the rate conversion occurs in stages rather than in one step. In this method, filter searching is performed exhaustively over all possible factorization of the conversion ratio, and also the filter complexity is measured based on direct realization rather than on estimation. It has been shown a designed multistage filter to have a less number of multiplications for filtering operation in comparison with a conventionally designed one. It has also been found that by allowing some variations of the filter architecture such as a halfband filter or a filter with multiple transition bands, the number of multiplications can be reduced further.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.6
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• pp.287-296
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• 2020

The study investigates the relationship and influence between religiosity, reward, and engagement in the public administration sector, both directly and causally via moderation. This study involved one hundred and twenty-three respondents in three local government organizations in Malang City, East Java Province, Indonesia, namely, the Malang City General Hospital, the Population and Civil Registry Office, and the Investment Office. The sampling method uses stratified random sampling from the total population of civil servants in Malang in the three institutions. The data analysis model of this study uses a quantitative approach with a unit of data analysis using the path analysis method. The analytical tools used are smart-PLS and SPSS. The results reveal that the direct combined effect of reward and religiosity has a positive and significant influence on the engagement. However, moderation between reward and commitment, which is bridged by religiosity, does not show positive and significant results. The non-positive relationship shown by testing moderation concludes that there is a separation of purpose between the portion of religiosity in the world of work, where religiosity in this study is only described as part of the concept of worship, and the relationship between the person and his God.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.9
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• pp.769-779
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• 2020

Self-efficacy has been extensively evaluated, but no studies have investigated the effect of self-efficacy on the self-reliance of women in poor-households economic productivity. This study analyzes self-efficacy as a personal factor, learning processes, and social support as an environmental factor towards the achievement of self-reliance in women from poor-households in productive economy businesses. Despite the dominant logic of this scheme, there is a need for field-based data regarding whether the variable really supports the sustainable empowerment of poor-households women. This study used the quantitative method through the survey technique. The samples of this study included 250 people collected from five regencies in Indonesia by using a multiple-stage random sampling. The data were analyzed with structural equation modeling. The results show that social support has a significant positive impact on the learning process; social support has a direct negative impact on self-efficacy. The learning process has a direct positive influence on self-efficacy, while social support has a non-significant impact on self-reliance. The learning process has a direct influence on self-reliance. Social support and the learning process both have significant positive impact on self-efficacy. Social support, learning process, and self-efficacy simultaneously have a positive impact on self-reliance in productive economic activities.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.4
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• pp.264-271
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• 2011

ILS(Instrument Landing System) is the international standard system for approach and landing guidance. ILS was adopted by ICAO(International Civil Aviation Organization) in 1947 and is currently being used in commercial systems. To design the digital transmitter and receiver modules that can be mounted in the integrated ILS, we propose the digital design methods of digital double AM modulator and demodulator using FPGA chip, DDS(Direct Digital Synthesizer) for generation of sampling clock, demodulator of DDC(Digital Down Converter) structure, and spectrum analyzer using DSP chip. We demonstrate the efficiency of the proposed design method through experiments using developed transmitter and receiver modules. This system can be used as a high-performance commercial system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.598-601
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• 2003

Most of all, DTC drive is very simple in its implementation because it needs only two hysteresis comparator and switching vector table for both flux and torque control. The switching strategy of a conventional direct torque control scheme which is based on hysteresis comparator results in a variable switching frequency which depends on the speed, flux, stator voltage and the hysteresis of the comparator. The amplitude of hysteresis band greatly influences on the drive performance such as flux and torque ripple and inverter switching frequency. In this paper the influence of the amplitudes of flux and torque hysteresis bands and sampling time of control program on the torque and flux ripples are investigated. Simulation results confirm the superiority of the DTC under the proposed method over the conventional DTC.

• Safety and Health at Work
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• v.15 no.1
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• pp.102-109
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• 2024

Background: In today's modern world, longer working hours, shift work, and working at night have become major causes of the disruption of our natural circadian rhythms. This study aimed to investigate the effects of the type of shift work (rotating vs. fixed day), duty period (on-duty vs. off-duty), and working period within each shift (nighttime vs. daytime) on the circadian rhythm characteristics of nurses who provide direct patient care. Methods: This cross-sectional study used a purposive sampling method. Cosinor analysis was applied to analyze the actigraphy data of nurses providing direct patient care for seven consecutive days. The linear mixed effects model was then used to determine any variances between shift type, duty period, and working period within each shift for the nurses. Results: The mesor value did not differ according to nurses' shift type, duty period, and working period within each shift. The amplitude was statistically higher in on-duty nurses and in daytime working hours. The acrophase was significantly delayed in nighttime working hours. As well as nurses in rotating shift had experience. Conclusion: Our findings revealed that the peak activity of nurses occurs significantly later at night while working and nurses working during nighttime hours may have a weaker or less distinct circadian rhythm. Thus, this study suggests that limits be placed on the number of rotating nighttime shifts for nurses.

• The Journal of Korean Institute of Next Generation Computing
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• v.15 no.5
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• pp.75-83
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• 2019

Direct volume rendering is a widely used method for visualizing three-dimensional volume data such as medical images. This paper proposes a method for applying depth-of-field effects to volume ray-casting to enable more realistic depth-of-filed rendering in direct volume rendering. The proposed method exploits a camera model based on the human perceptual model and can obtain realistic images with a limited number of rays using jittered lens sampling. It also enables interactive exploration of volume data by on-the-fly calculating depth-of-field in the GPU pipeline without preprocessing. In the experiment with various data including medical images, we demonstrated that depth-of-field images with better depth perception were generated 2.6 to 4 times faster than the conventional method.

• Journal of the East Asian Society of Dietary Life
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• v.7 no.2
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• pp.199-210
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• 1997

The purpose of this study was to investigate the mutual relationship between food preference and nutrient intake status of high school students, based on the their personal characters which are sex, age, family type, number of family, mother's age, occupation, and school career. 439 students were selected with random stratified cluster sampling method. The study used a self-administrated questionnaire and 24-hour recall method for 5 days as instrument tools. Statistical methods applied to analyze the data were frequency, percent, Willcoxon Rank-sum test, Kruskal-Wallis test, ${x^2}-test$ by contingence table, and Spearman's correlation coefficient in non parametric statistical methods. Some of interesting results are as follows : 1. The correlation between sex and the set of characters of mother's age, school career and income is highly significant. However there is no any significant difference on the kinds of job and the types of family. 2. The relation between the preference of main dishes and the nutrient intake show a significant difference except to the noodles. This marks that preference of main dishes shows a direct proportion with the nutrient intakes except for the fat, vitamin A, vitamin C. 3. The preference of animal food marks a direct proportion with the nutrients such as energy, protein, fat, fiber, phosphorus, iron, vitamin $B_{1}$, vitamin $B_{2}$, and niacin 4. The preference of vegetable food gives some influence on the nutrient intake but the preference of soup is insignificant, the preference of Kimchi is in reverse proportion, and the preference of vegetable marks a direct proportion with the nutrient intake. 5. The preference of snacks marks a direct proportion with all kinds of nutrients intake except for the vitamin A, and vitamin C.

• ETRI Journal
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• v.43 no.2
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• pp.324-331
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• 2021

Space-based automatic dependent surveillance-broadcast (ADS-B) is an important emerging augmentation of existing ground-based ADS-B systems. In this paper, the problem of space-based ultra-long-range reception processing of ADS-B signals is described. We first introduce a header detection method for accurately determining the pulse position of a weak ADS-B signal. We designed a signal encoding method, shaping method, and fitness function. We then employed a genetic algorithm to perform high-precision frequency and phase estimations of the detected weak signal. The advantage of this algorithm is that it can simultaneously estimate the frequency and phase, meaning a direct coherent demodulation can be implemented. To address the computational complexity of the genetic algorithm, we improved the ratio algorithm for frequency estimation and raised the accuracy beyond that of the original ratio algorithm with only a slight increase in the computational complexity using relatively few sampling points.