• The Journal of the Acoustical Society of Korea
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• v.15 no.2
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• pp.21-32
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• 1996

The performance of the energy density control algorithm for controlling a broadband noise is evaluated in a one-dimensional enclosure. To avoid noncausality problem of a control filter, which often happens in a frequency domain optimization, analyses presented in this paper are undertaken in the time domain. This approach provides the form of the causally constrained optimal controller. Numerical results are presented to predict the performance of the active noise control system, and indicate that imp개ved global attenuation of the broadband noise can be achieved by minimizing the energy density, rather than the squared pressure. It is shown that minimizing the energy density at a single location yields global attenuation results that are comparable to minimizing the potential energy. Furthermore, unlike the squared pressure control, the energy density control does not demonstrate any dependence on the error sensor location for this one-dimensional field. A practical implementation of the energy-based control algorithm is presented. Results show that the energy density control can be implemented using the two sensor technique with a tolerable margin of performance degradation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.192-199
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• 2016

This article examines the location strategies of coffee franchises in Gyeonggi province. Due to its large population, broad area, and diverse industrial structure, Gyeonggi province is an ideal dataset for empirical testing of the location strategies. We collect the addresses of five major coffee franchises stores, convert them into geographic coordinates using Google Maps Geocoding API, and compute Haversine distances both between stores of the same franchise and between stores of different franchises. This novel approach leads to three discoveries. First, coffee-consuming age population is positively related to the number of stores and more strongly for commercial areas with a large floating population. Second, one third of Starbucks stores have another Starbucks store within a radius of 300m, which empirically confirms the 'Focused Destroy Strategy' of Starbucks that has multiple stores in central business districts. Third, for 80% of Starbucks stores, we can find Ediya stores within 500m, which supports Ediya's 'Next-to-Starbucks Strategy'. Our research methods can be efficiently applied to the analyses of other retail businesses such as convenience stores, fast food restaurants, and mobile phone shops.

• Journal of Engineering Education Research
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• v.13 no.3
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• pp.3-10
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• 2010

Human resources specialized in product development (PD) being essential in industry to enhance their competitiveness in the market with differentiated products, the PD curricula of domestic universities are in need of restructuring to better provide a comprehensive and diverse spectrum of knowledge as well as practical experiences for PD. We compared the PD curricula of selected domestic and foreign universities and identified advanced features of PD curricula. The major portion of the information used in our benchmarking of the seven, three domestic and four foreign, universities is obtained through their official websites. At domestic universities, the PD curricula comes in different sizes and is administered at the departmental level. On the other hand, each foreign university has her own unique form of PD curricula which is formulated on the firm basis of multidisciplinary collaboration among schools of Engineering, Management, and Arts with diversified program options ranging from giving course credits to offering various certificates and degrees. The industrial sponsorship in the form of financial support and mentorship at foreign universities is much more noticeable than at domestic universities. The survey results of the present study can be effectively utilized to develop an effective PD curriculum.

• Journal of Science Education
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• v.34 no.1
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• pp.1-11
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• 2010

This study analyzes the factors influencing academic achievement on mathematic and scientific subject and its change in Korean youth by using a sample from KYPS(Korea Youth Panel Survey) data. The results are as follows: First, academic achievement on mathematic and scientific subject of Korean youth shows quadratic curve that their interrelationship between intercept and slope of academic achievement are negative which is statistically significant. Second, analysis of Latent Growth Models shows that parents, teacher, peer group, self esteem, income of family, high school tracks are found to be a statistically significant factor on mathematic. And scientific subject is affected by parents, teacher, peer group, self esteem, income of family, high school tracks. Also, Interesting finding is that father's job is not significant to dependent variables. These findings show that academic achievement on mathematic and scientific subject of the Korean youth are the quadratic curve and influenced by parents, teacher, peer group, self esteem, income of family, high school tracks. To improve youth's mathematic and scientific, Korea educational fields and educators should have policy to care youth's relationship with parents, teachers and self esteem.

• Journal of The Korean Association For Science Education
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• v.36 no.4
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• pp.669-679
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• 2016

The purpose of this study is to investigate the current status of STEAM (Science, Technology, Engineering, Arts, and Mathematics) education in schools by asking a variety of questions including "why and how often they implement STEAM education." This study conducted an online survey on 11,526 elementary, middle, and high schools in South Korea, with the response rate being 56.8% (N = 6,473). To highlight key findings, first, our descriptive analyses suggested that if those that did not respond to the survey were assumed not to have implemented STEAM education, approximately 27.1% (N = 3,127) of all schools in South Korea were believed to have implemented STEAM at best. The highest rate of implementation of STEAM education was found in elementary schools (30.8%), followed by middle (27.4%) and high (17.5%) schools. Second, in contrast with the result for the rate of implementation of STEAM education, high schools showed the highest level of satisfaction. Third, the most important reason for implementing STEAM education within a school was found to be teachers' voluntary efforts or intrinsic motives, followed by support from the provincial office of education. Fourth, the most important reason for not implementing STEAM education was found to be the lack of consensus among teachers. Together, findings highlight the importance of the role of teachers in implementing STEAM education. Offered are policy implications for the better implementation of STEAM education.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.51-59
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• 2010

The sediments and soils around a mine are likely to be exposed to contamination of arsenic (As) through mining operations. In this study, the factors associated with As movement in soils around a closed zinc (Zn) mine were evaluated by the relationship of As distributions to physico-chemical properties of soils. A sequential extraction scheme, based on a soil P fractionation, was used to assess the As distributionsin solid phases. A significant difference in As distributions was found between paddy and upland soils. While As contents of paddy soils increased with soil depth, those of upland soils decreased with soil depth. In upland soils, As showed additional significant relationships to oxides of Si, Al and Fe. Although a major fraction of As in soils was found to be in the NaOH extractable fraction, As exhibited highly significant relationship to the Zn species that apparently originated from the mine. Therefore, As mobility around Zn mine seems to be governed by mass flow of the particulates containing As-associated Zn in paddy soils, whereas retention reactions such as adsorption, complexation, and precipitation seem to predominate in upland soils.

• The Plant Pathology Journal
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• v.26 no.4
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• pp.313-320
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• 2010

Genetic instability of the rice blast fungus Magnaporthe oryzae has been suggested as a major factor underlying the rapid breakdown of host resistance in the field. However, little information is available on the mechanism of genetic instability. In this study, we assessed the stability of repetitive DNA elements and several key phenotypic traits important for pathogenesis after serially transferring two isolates though rice plants and an artificial medium. Using isolate 70-15, we obtained a total of 176 single-spore isolates from 10 successive rounds of culturing on artificial medium. Another 20 isolates were obtained from germ tubes formed at the basal and apical cells of 10 three-celled conidia. Additionally, 60 isolates were obtained from isolate KJ201 after serial transfers through rice plants and an artificial medium. No apparent differences in phenotypes, including mycelial growth, conidial morphologies, conidiation, conidial germination, appressorium formation, and virulence, or in DNA fingerprints using MGR586, MAGGY, Pot2, LINE, MG-SINE and PWL2 as probes were observed among isolates from the same parent isolate. Southern hybridization and sequence analysis of two avirulence genes, AVR-Pita1 and AVR-Pikm, showed that both genes were also maintained stably during 10 successive generations on medium and plants. However, one reversible loss of restriction fragments was found in the telomere-linked helicase gene (TLH1) family, suggesting some telomere regions may be more unstable than the rest of the genome. Taken together, our results suggest that phenotype and genotype of M. oryzae isolates do not noticeably change, at least up to 10 successive generations on a cultural medium and in host plants.

• The Journal of the Korea Contents Association
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• v.19 no.6
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• pp.10-23
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• 2019

Although social big data can provide a multi-faceted perspective on school bullying experiences among children and adolescents, the complexity and variety of unstructured text presents a challenge for systematic collection and analysis of the data. Development of an ontology, which identifies key terms and their intricate relationships, is crucial for extracting key concepts and effectively collecting data. The current study elaborated on the definition of an ontology, carefully described the 7 stage development process, and applied the ontology for collecting and analyzing school bullying social big data. As a result, approximately 2,400 key terms were extracted in top-, middle-, and lower-level categories, concerning domains of participants, causes, types, location, region, and intervention. The study contributes to the literature by explaining the ontology development process and proposing a novel alternative research model that uses social big data in school bullying research. Findings from this ontology study may provide a basis for social big data research. Practical implications of this study lie in not only helping to understand the experience of school bullying participants, but also in offering a macro perspective on school bullying as a social phenomenon.

• (The)Korea Educational Review
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• v.23 no.2
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• pp.5-30
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• 2017

In this study, we analyzed the longitudinal effect of participation in an overseas exchange student program on foreign language competence, intercultural competence, and personal development. Data were collected over three time points from the pre-, post-, and post-post tests with Korean college students who participated in an overseas exchange program. Hierarchical linear model was conducted to examine whether the change of participation effects exists over time and which predictors affected outcomes. The results of unconditional growth model showed that foreign language competence, cultural competence, and personal development showed statistically significant differences in their initial status prior to departure to participate in an overseas program as well as their growth rate. The results of conditional growth model showed that parents' level of education and overseas experiences before college affected the initial status of foreign language competence, and gender and overseas experience before college affected those of cultural competence as well as personal development. In case of growth rate, overseas experience before college and destination country/region affected foreign language competence, and interactions between Korean participating students and local students affected cultural competence. For personal development, only overseas experiences before college affected its growth rate. Lastly, relevant discussion and implications were provided.

• Journal of Life Science
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• v.33 no.4
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• pp.343-348
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• 2023

Acne is one of the most common skin diseases, mainly occurring in adolescence. The pathophysiology of acne involves not only hormonal, genetic and environmental factors, but also other factors including hyperseborrhea, inflammation, over-keratinization of follicular keratinocytes and overgrowth of Cutibacterium acnes (C. acnes). Cannabidiol (CBD) is known to relieve pain, stress and inflammation. Moreover, cannabis extracts containing CBD have been reported to be effective in treating acne. However, the therapeutic effect of CBD on acne remains unclear. Therefore, this study aimed to investigate the effect and mechanism of CBD on lipogenesis in SEB-1 sebocytes. We treated sebocytes with CBD and found that it not only inhibited lipid synthesis, but also inhibited cell proliferation by inducing apoptosis. We then demonstrated that sterol response element-binding protein-1 (SREBP-1) mediates the inhibitory effect of CBD on lipogenesis. Furthermore, Akt and adenosine monophosphate-activated protein kinase (AMPK), upstream regulators of SREBP-1, were regulated by CBD treatment. Taken together, our studies demonstrate that CBD inhibits adipogenesis by regulating the Akt/AMPK-SREBP-1 signaling pathway, providing potential for use as a therapeutic agent for acne. Further research is needed to confirm the effect of CBD on inflammation caused by hyperkeratosis, which will increase the possibility of using CBD for acne treatment.