• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.777-786
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• 2003

The phase noise characteristics of the phase-locked loop frequency synthesizer were predicted based on the analysis for phase noise contribution of noise sources. The proposed phase noise model in this paper more accurately predicts the phase noise spectrum of frequency synthesizer. To accurately model the phase noise contribution of noise sources in frequency synthesizer, the phase noise sources were analyzed via modeling of the frequency divider and phase noise components using Leeson model for reference signal source and VCO. The phase noise transfer functions to VCO from noise sources were analyzed by superposition theory and linear operation of phase-locked loop. To evaluate the phase noise prediction model, the frequency synthesizers were fabricated and were evaluated by measured data and prediction data.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.2
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• pp.347-353
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• 2017

In order to prohibit global warming, various kinds of regulatory policies have been established in the whole world. One example is the establishment of the Renewable Portfolio Standard. It requires the increased portion in energy production from renewable energy sources. The Republic of Korea adopted the act on the promotion of the development, use, and diffusion of new and renewable energy since 2012. However, in spite of the effort on the consideration of the renewable energy sources, it was reported the carbon intensity of electricity in Korea was not that low in 2015. Thus, it is required to examine the recent state of the utilization degree of the renewable energy sources in Korea. This paper analyzed the statistical data provided by Korea Power Exchange (KPX) to examine any problems and solutions for generating electricity from the renewable energy sources. We focused on the generation capacity provided by the power plants participated in the market, the electric power trading amount, and the utilization coefficient for 10 years. By analyzing the data, we provide an alternative to solve some imbalance among the factors contributing to renewable energy use.

• Analytical Science and Technology
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• v.35 no.2
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• pp.69-81
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• 2022

The method of measuring and classifying the energy category of neutrons directly using raw data acquired through a CZT detector is not satisfactory, in terms of accuracy and efficiency, because of its poor energy resolution and low measurement efficiency. Moreover, this method of measuring and analyzing the characteristics of low-energy or low-activity gamma-ray sources might be not accurate and efficient in the case of neutrons because of various factors, such as the noise of the CZT detector itself and the influence of environmental radiation. We have therefore developed an efficient method of analyzing radiation characteristics using a neutron and gamma-ray analysis algorithm for the rapid and clear identification of the type, energy, and radioactivity of gamma-ray sources as well as the detection and classification of the energy category (fast or thermal neutrons) of neutron sources, employing raw data acquired through a CZT detector. The neutron analysis algorithm is based on the fact that in the energy-spectrum channel of 558.6 keV emitted in the nuclear reaction ¹¹³Cd + ¹n → ¹¹⁴Cd + in the CZT detector, there is a notable difference in detection information between a CZT detector without a PE modulator and a CZT detector with a PE modulator, but there is no significant difference between the two detectors in other energy-spectrum channels. In addition, the gamma-ray analysis algorithm uses the difference in the detection information of the CZT detector between the unique characteristic energy-spectrum channel of a gamma-ray source and other channels. This efficient method of analyzing radiation characteristics is expected to be useful for the rapid radiation detection and accurate information collection on radiation sources, which are required to minimize radiation damage and manage accidents in national disaster situations, such as large-scale radioactivity leak accidents at nuclear power plants or nuclear material handling facilities.

• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1369-1378
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• 2017

The present paper reports the development of a computational code based on the Adaptive Group of Ink Drop Spread (AGIDS) for reconstruction of the neutron noise sources in reactor cores. AGIDS algorithm was developed as a fuzzy inference system based on the active learning method. The main idea of the active learning method is to break a multiple input-single output system into a single input-single output system. This leads to the ability to simulate a large system with high accuracy. In the present study, vibrating absorber-type neutron noise source in an International Atomic Energy Agency-two dimensional reactor core is considered in neutron noise calculation. The neutron noise distribution in the detectors was calculated using the Galerkin finite element method. Linear approximation of the shape function in each triangle element was used in the Galerkin finite element method. Both the real and imaginary parts of the calculated neutron distribution of the detectors were considered input data in the developed computational code based on AGIDS. The output of the computational code is the strength, frequency, and position (X and Y coordinates) of the neutron noise sources. The calculated fraction of variance unexplained error for output parameters including strength, frequency, and X and Y coordinates of the considered neutron noise sources were $0.002682{\sharp}/cm^3s$, 0.002682 Hz, and 0.004254 cm and 0.006140 cm, respectively.

• Journal of Korean Institute of Industrial Engineers
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• v.32 no.3
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• pp.236-241
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• 2006

Monitor height is one of the key factors in the VDT workstation design. Most of the previous studies have focused on traditional VDT workplace where the operators performed data entry or word processing tasks using single monitor. This study aimed to suggest proper monitor height when the main task was monitoring information from different number of information sources. Twelve male students participated in three experiments: single information source (one monitor), two information sources (one monitor and one CCTV), and three information sources (one monitor, one CCTV and a window). Subjects performed monitoring tasks for 10 minutes with 3 different monitor center heights : 89.0 cm (Low), 111.3 cm (Middle), and 124.8 cm (High). Surface EMG signals of five neck muscles, subjective discomfort ratings, preference, and working postures were recorded. Results indicated that the middle height was proper for one monitor condition, but the low monitor height was recommended for more than two information sources.

• Journal of the Korean housing association
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• v.5 no.2
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• pp.51-63
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• 1994

The purpose of this study are to examine the types and sources of information used for housing choices and to figure out the related factors. Data are collected through self-administered questionnaires designed for this study, and the sample consists of 396 households in Pusan and Ulsan. The purposes are accomplished through descriptive statistics and multiple regression analyses. Based on the results of analysis, housing information are divided into four specific types : economic. technical, housing unit, and neighborhood information. It is found that housing unit information including housing quality and economic information such as housing prices are identified as the most important ones for current and future housing choices. The most useful sources of housing information utilized for current housing are friends, relatives and neighbors. In addition, model house, real estate office, newspaper and adverizement are the another useful sources for housing information. Among them, the model house is the most helpful one for variety of housing information. Young households and those with a head whose occupation is professional/managerial tend to have higher recognition of the importance of housing information than do the other groups. The households currently living in small apartment and with a young eldest child are likely to have higher recognition of the importance of econimic information. Tenure type, the occupation of the household head, the age of the eldest child, and length of residence are the significant explanatory variables of the recognition of the importance of housing unit information.

• Journal of the Korean Society of Costume
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• v.55 no.4 s.94
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• pp.16-28
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• 2005

The purposes of this study were to understand the buying patterns of adult women according to impulse shopping, benefits sought, and selecting information sources. This subjects of this study were 509 adult women from the age 20's to the age of 40's. This data were analyzed by using factor analysis multi regression analysis, analysis of variance, Scheffe' test. The results of this study were outlined as follow: 1. Differences among ages (the 20's, the 30's, and the 40's) in impulse shopping were as follow: The 30's bought more cosmetics to change their mood compared to the 20's or the 40's, and the 20's and the 30's bought more cosmetics matching to their images compared to the 40's. 2. From the aspects of benefits sought, the 20's and the 30's were more seriously consider the fame of brands compared to the 40's, showing they were different from the 40's. 3. From the aspects of selecting information sources about cosmetics, the 20's were more actively utilizing both human information sources and non-human information sources compared to the 30's and the 40's.

• Fashion & Textile Research Journal
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• v.14 no.2
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• pp.230-241
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• 2012

The purpose of this study was to examine the effect of power sources of department store and fashion company, and salesperson's job consciousness on job satisfaction in the middle management system of department store. Questionnaire data from 193 salespeople in the middle management of department store were analyzed by reliability analysis, factor analysis, correlation analysis, multiple regression analysis, hierarchical regression analysis. The results of this study were as follows: First, coercive power, informational and expert power, and referent power of department store had significant effects on job satisfaction. The coercive power of department store had a negative influence on job satisfaction, while informational and expert power, and referent power of department store had a positive influence on job satisfaction. Second, referent power, expert power, reward power, coercive power of fashion company had a positive influence on job satisfaction. Third, referent power of department store had a greater influence on job satisfaction than other power sources. Fourth, job commitment and pride, prospect awareness had a positive influence on job satisfaction, while professional self-awareness had no effect on job satisfaction.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.9
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• pp.755-767
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• 2020

The objective of this study is to examine and provide guidelines for regional governments, communities, and the private sector in planning and implementing poverty-reduction activities that are more effective, efficient, and targeted. Besides, this research's specific aims are: 1) increasing the rate of regional economic growth through optimization of potential sources of local income, 2) increasing per-capita income, and 3) reducing poverty, unemployment, and social-economic inequality of the community. The study was conducted in North Morowali District, Central Sulawesi Province, Indonesia, in 2018-2019. The research approach used quantitative and qualitative descriptive analysis. Data sources include sources from the Focus Group Discussion (FGD) and Regional Statistics. The results of this study are based on the Millennium Development Goals (MDG's) indicators that there are four priority scales in poverty reduction, namely, Health and Infrastructure (Priority I), Education (Priority II), Food stability (Priority III), and Population and Employment (Priority IV). Therefore, as a solution to poverty alleviation strategies, the cost approach through regional economic optimization and local income sources and community empowerment factors are essential. Apart from that, the involvement between elements (government, organizations, society, universities, and institutions) is expected to continue as an effort to realize poverty reduction can be optimally overcome.

• The Journal of Korea Robotics Society
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• v.12 no.4
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• pp.402-410
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• 2017

Acoustic based localization is essential to operate autonomous robotic systems in underwater environment where the use of sensorial data is limited. This paper proposes a localization method using artificial underwater acoustic sources. The proposed method acquires directional angles of acoustic sources using time difference of arrivals of two hydrophones. For this purpose, a probabilistic approach is used for accurate estimation of the time delay. Then, Gaussian sum filter based SLAM technique is used to localize both acoustic sources and underwater vehicle. It is performed by using bearing of acoustic sources as measurement and inertial sensors as prediction model. The proposed method can handle directional ambiguity of time difference based source localization by generating Gaussian models corresponding to possible locations of both front and back sides. Through these processes, the proposed method can provide reliable localization method for underwater vehicles without any prior information of source locations. The performance of the proposed method is verified by experimental results conducted in a real sea environment.