• Bulletin of the Korean Mathematical Society
• /
• v.58 no.3
• /
• pp.659-668
• /
• 2021

Let R be a semiprime ring with maximal right ring of quotients Q_mr(R), and let n₁, n₂, …, n_k be k fixed positive integers. Suppose that R is (n₁+n₂+⋯+n_k)!-torsion free, and that f : 𝜌 → Q_mr(R) is an additive map, where 𝜌 is a nonzero right ideal of R. It is proved that if [[…[f(x), x^n₁], …], x^n_k] = 0 for all x ∈ 𝜌, then [f(x), x] = 0 for all x ∈ 𝜌. This gives the result of Beidar et al. [2] for semiprime rings. Moreover, it is also proved that if R is p-torsion, where p is a prime integer with p = Σ^k_i=1 n_i and if f : R → Q_mr(R) is an additive map satisfying [[…[f(x), x^n₁], …], x^n_k] = 0 for all x ∈ R, then [f(x), x] = 0 for all x ∈ R.

• Korean Journal of Childcare and Education
• /
• v.9 no.2
• /
• pp.239-262
• /
• 2013

The purpose of this study was to examine the types of image that early childhood teachers have about nursery teachers in detail in an effort to provide some information on how to build an ideal image of a nursery teacher. Another goal was to determine the right directions for teacher education based on the subjective opinions of early childhood teachers, which has not been covered in earlier studies. The Q-methodology was utilized to determine the awareness of early childhood teachers about the types of the images of nursery teachers and each type's characteristics. A Q-population was constituted by 310 types of images based on the results of earlier studies about the images of nursery teachers, and 48 Q-samples were selected according to frequency. And then 20 nursery teachers and 20 kindergarten teachers were asked to classify the images of nursery teachers in nine stages by using the Q-sort, and the data were analyzed by the statistical package PASW 18.0. As a result, four different types of images appeared that the early childhood teachers had about nursery teachers, and the images were respectively named 'a practical-teaching-oriented type of teacher', 'a negative-system critical type of teacher', 'a positive-humanistic type of teacher' and 'a neutral-emotionally type of teacher'.

• Journal of Korean Academy of Nursing
• /
• v.24 no.3
• /
• pp.364-376
• /
• 1994

This study was initiated to find the characteristic awareness of disease in Korean culture and then, with its applying to psychological nursing, to help cancer victims cope with their disease. Research period was from Dec. 1, 1989 to Aug.3, 1992. The research method, while the method of face-to-face interview with 33 cancer victims were mainly adopted, was to identify the causal perception through analyses of literature and traditional sayings deeply rooted in Korean culture. The causal perceptions were differentiated into 4 sections, which apply to 32 cancer victims with Q-sorting. Be-ing coded into grades from 1 to 9, the data were analyzed with the aid of Quanal program on PC ; in analyzing Q-factor principal component analysis method was used. The results were revealed as follows : 1. Subject victims owe their disease to 1) the omnipotent and animating powers in Shamanism rooted in Korean culture, 2) their intimate persons, i.e. their husband, wife, children, or other fellows ameng their groups. 3) victims themselves, and 4) nowhere, for they thought the disease is the struggle with their own self. 2. In Q-methodology analysis, cancer victims are categorized into 5 types. The first type, self-mastery type, consisting of 11 subjects, has the characteristic of overcoming their disease with their own strong will or by the help of the Omnipotent God, which is estimated to be the ideal type to cope with the disease. The second type, omnipotent & animating powers-dependent type, consisted of 7 subjects, who have the causal perception of traditional shamanism. The third type, intimate person-dependent type, consisted of 4, all of whom are women and whose causal perception has the characteristic of the their complains about each member of their family, espectially about their husband. The fourth type, fate-recipient type, was the com-plex form of the first and the second types. It consisted of 6 subjects, to whom cancer had meant bad fate coming on them but had to be overcome by their strong will. The fifth type, personal type, consisted of 4, whose causal perception is toward themselves personality It is hoped that the study provide the chance of developing nursing intervention to help cancer victims accept and overcome their disease as their own reality instead of attributing to anyone or any-thing else.

• Journal of Communications and Networks
• /
• v.15 no.4
• /
• pp.383-397
• /
• 2013

In this paper, the sensitivity of massive antenna arrays and digital beamforming to radio frequency (RF) chain in-phase quadrature-phase (I/Q) imbalance is studied and analyzed. The analysis shows that massive antenna arrays are increasingly sensitive to such RF chain imperfections, corrupting heavily the radiation pattern and beamforming capabilities. Motivated by this, novel RF-aware digital beamforming methods are then developed for automatically suppressing the unwanted effects of the RF I/Q imbalance without separate calibration loops in all individual receiver branches. More specifically, the paper covers closed-form analysis for signal processing properties as well as the associated radiation and beamforming properties of massive antenna arrays under both systematic and random RF I/Q imbalances. All analysis and derivations in this paper assume ideal signals to be circular. The well-known minimum variance distortionless response (MVDR) beamformer and a widely-linear (WL) extension of it, called WL-MVDR, are analyzed in detail from the RF imperfection perspective, in terms of interference attenuation and beamsteering. The optimum RF-aware WL-MVDR beamforming solution is formulated and shown to efficiently suppress the RF imperfections. Based on the obtained results, the developed solutions and in particular the RF-aware WL-MVDR method can provide efficient beamsteering and interference suppressing characteristics, despite of the imperfections in the RF circuits. This is seen critical especially in the massive antenna array context where the cost-efficiency of individual RF chains is emphasized.

• Journal of Power Electronics
• /
• v.11 no.3
• /
• pp.360-368
• /
• 2011

This paper proposes an active frequency with a positive feedback in the d-q frame anti-islanding method suitable for a robust phase-locked loop (PLL) algorithm using the FFT concept. In general, PLL algorithms for grid-connected PV PCS use d-q transformation and controllers to make zero an imaginary part of the transformed voltage vector. In a real grid system, the grid voltage is not ideal. It may be unbalanced, noisy and have many harmonics. For these reasons, the d-q transformed components do not have a pure DC component. The controller tuning of a PLL algorithm is difficult. The proposed PLL algorithm using the FFT concept can use the strong noise cancelation characteristics of a FFT algorithm without a PI controller. Therefore, the proposed PLL algorithm has no gain-tuning of a PI controller, and it is hardly influenced by voltage drops, phase step changes and harmonics. Islanding prediction is a necessary feature of inverter-based photovoltaic (PV) systems in order to meet the stringent standard requirements for interconnection with an electrical grid. Both passive and active anti-islanding methods exist. Typically, active methods modify a given parameter, which also affects the shape and quality of the grid injected current. In this paper, the active anti-islanding algorithm for a grid-connected PV PCS uses positive feedback control in the d-q frame. The proposed PLL and anti-islanding algorithm are implemented for a 250kW PV PCS. This system has four DC/DC converters each with a 25kW power rating. This is only one-third of the total system power. The experimental results show that the proposed PLL, anti-islanding method and topology demonstrate good performance in a 250kW PV PCS.

• International Journal of Advanced Culture Technology
• /
• v.11 no.2
• /
• pp.152-161
• /
• 2023

Modern people live a life connected with the real world and the virtual world by relying on the new media of enterprises and social consumption led by innovative technologies. In this environment, virtual influencers actively communicate with consumers and build relationships through social media, which is a new marketing tool that has attracted widespread attention. From a business perspective, it is necessary to have a solid understanding of this phenomenon, and then explore communication strategies to effectively develop virtual influencers. To investigate followers' preference for virtual influencers, this study employs the Q-method, which studies human subjective attributes, an empirical research effort to uncover complex issues in human subjectivity. To determine the factors that trigger people's voluntary and active practice and the preference degree of virtual influencers, the Q method is implemented to examine human subjectivity, thoughts and attitudes. According to the results of this study, virtual influencers are a new group of idols full of vitality. The interviews found that there are still many virtual influencers who do not know about followers, but each type can be clearly understood through the intuitive understanding of the interviewees. Divided out, type 1 one egoideal virtual influencers aim to represent an idealized version of the creator or target audience. Embodies ideal physical characteristics, personality or lifestyle desired by the audience. Type 2 is charismatic and attractive, and has the characteristics of most virtual influencers. It is suggested that it can be developed into a potential type, doing brand cooperation, and content production on social media platforms. Type 3: Game animation, derived from the image of characters in games or comics, with stylized features and energetic personalities, which can be integrated into games or entertainment experiences. Type 4 development potential type is the most successful type among virtual imagers, and it is also the purpose of marketing virtual influencers. It is essential that brand endorsement on social media platforms, integrated marketing, and driving advertising traffic. It is recommended to improve production technology to reduce investment costs.

• Korean Journal of Environment and Ecology
• /
• v.33 no.5
• /
• pp.552-564
• /
• 2019

The purpose of this study was to investigate vegetation characteristics of evergreen broad-leaved forests in the area of Duryunsan Provincial Park, where the deciduous broad-leaved trees and evergreen broad-leaved trees are mixed and thus had a high botanical value. To investigate the vegetation characteristics, we installed 40 quadrats with an area of $100m^2$ each for survey and analysis. Haenam-gun, where the Duryunsan Provincial Park is located, is a warm-temperate forest region. The meteorological data for the past 40 years showed a coldness index of $-8^{\circ}C$, a monthly warmth index of $109.2^{\circ}C$, and annual mean precipitation of 1,310.5mm, indicating it is an ideal habitat for the distribution of evergreen broad-leaved forest. The results of community classification based on TWINSPAN showed three categories of vegetation communities in the surveyed region: Quercus acuta community-I, Q. acuta community-II, and Neolitsea sericea-Aphananthe aspera community. In the evergreen broad-leaved forest in the Duryunsan Provincial Park, Q. acuta dominant in the canopy were expanding their presence in the understory. In addition to the Q. acuta, N. sericea and Cinnamomum yabunikkei, which are evergreen broad-leaved trees of the canopy, were found in all layers. The deciduous broad-leaved trees such as Q. variabilis, Q. serrata, and Carpinus tschonoskii were culled, and the transition to Q. acuta evergreen broad-leaved trees was ongoing. N. sericea community appeared locally. The species diversity index of N. sericea-A. aspera community was lower at 1.0798 than that of Q. acuta Community-I at 1.3208 and Q. acuta Community-II at 1.4916.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.5
• /
• pp.936-943
• /
• 2009

Dynamic voltage restorer(DVR) is now more preferable enhancement than other power quality enhancement in industry to reduce the impact of voltage faults, especially voltage sags to sensitive loads. The main controllers for DVR consists of PLL(phase locked loop), compensation voltage calculator and voltage compensator. PLL detects the voltage faults and phase. Compensation voltage calculator calculates the reference voltage from the source voltage and phase. With calculated compensation voltage from PLL, voltage compensator restores the source voltage. If PLL detect ideal phase, compensation voltage calculator calculates ideal compensation voltage. Therefore, PLL for DVR is very important. This paper proposes the new method of PLL in DVR. First, the power circuit of DVR system is analyzed in order to compensate the voltage sags. Based on the analysis, new PLL for improving transient response of DVR is proposed. The proposed method uses band rejection filter(BRF) at q-axis in synchronous flame. In order to calculate compensation voltage in commercial instruments, the PQR theory is used. Proposed PLL method is demonstrated through simulation using Matlab-Simulink and experiment, and by checking load voltage, confirms operation of the DVR

• Korean Journal of Plant Resources
• /
• v.30 no.2
• /
• pp.213-218
• /
• 2017

Rice is the staple food of at least half of the world's population. Due to global warming, the weather is difficult to forecast nowadays. Therefore, it is necessary to breed various breeding to respond to such changes in the environment. This study was conducted to analyze the QTL about plant form, culm length, ear number and ear length by using 120 lines by anther culture, a cross between the Indica variety Cheongcheong and Japonica variety Nagdong. DNA marker was selected on the QTLs gene, and the following results were obtained. CNDH (Cheongcheong Nagdong Doubled Haploid) lines frequency distribution table curves about culm length, ear number and ear length exhibited showed a continuous variation close to a normal distribution. QTL analysis result, on culm length qPlL1-1 and qPlL1-2 were detected on the chromosome 1 and qPlL5 was detected on the chromosome 5. However, on ear length qPL2, qPL3 and qPL10, were detected on the chromosome 2, 3 and 10, while on ear number qPN1-1 and qPN1-2 were detected on the chromosome 1, qPN9 was detected on the chromosome 9. The QTLs related to culm length was found to chromosomes 5 and LOD scores were 3.81. The QTLs related to ear length was found to chromosomes 2 and 3 LOD scores were 7.13 and 3.20. The QTLs related to ear number was found to chromosome 9 and LOD scores were 4.27. Twenty two (22) Japonica cultivars and 12 Indica cultivars were analyzed polymorphisms, using selected 9 markers from the result about plant form analysis. RM5311, RM555 and RM8111 about the culm length, the ear length and number of ear were selected on the standard of Cheongcheong and Nagdong. Each rate of concordances about the culm length, the ear length and number of ear are 44.11%, 41.17% and 44.11%.

• 한국노년학
• /
• v.38 no.4
• /
• pp.871-889
• /
• 2018

This study aims to explore social participation needs among the elderly in Korea from the perspective of the elderly participant's. 40 Q-samples are drawn from the Q-population including attitudes and needs toward social participation in later life based on news articles, essays, research, documentary, and television shows. 35 subjects are analysed by the QUANL program and the types of social participation needs are divided into four patterns which accounted for 60.16% of the total variance. The elderly's portrayal of an ideal social participation is about making independent decisions and being able to actively participate in the activities they chose to do. However, their most undesirable scenario would be being confused and uncertain of what they should do the remainder of their lives. The needs of social participation among the elderly varies on four indicators such as ego, social capital, life satisfaction, life vitality and these four indicators have two sub-categories with a total of 8 types of classification. These 8 types differ by priorities, adaptation to life changes, motivation to social participation, and desired activity. Findings suggest that researchers and policy makers need to consider service user perspective on social participation in later life, not service provider perspective.