• The Journal of the Korea Contents Association
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• v.11 no.12
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• pp.969-975
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• 2011

The purpose of this study is to investigate the effects of learners' self-motivational attitudes, use of instructional function, and understanding of successful learning on achievement in college e-learning classes. The study analyzed 297 college students' questionnaire about their internet learning attitudes based on how they understand e-learning and use various internet functions for their learning achievement. After factor analyses, the results found that there were three major factors such as self-motivational attitude, use of instructional function, and understanding of successful learning out of 15 survey items. Multiple regression showed that the self-motivational factor affects the learning achievement with overall three factors analyses. This result indicates that college e-learning classes should focus on the analysis of learners' self-motivational issues in college e-learning classes. This study suggest that the relationship between learners' e-learning experience and learning achievement should be examined in the near future to show how it affects on learners e-learning class management and their achievement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.2
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• pp.357-372
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• 2012

Existing e-learning systems not only require complex admission processes but also do not give stepwise education methods according to individual learners' characteristic. These circumstances cause learners to lose educational interest so that their educational efficiency decreases. In particular, the present e-learning systems do not provide educational approaches suitable for infant and elementary children. Under this system, the e-learning education for children does not proceed completely without guardians. To solve this problem, we design and implement an English e-learning system for elementary children based on friendly and comfortable user interfaces. For children, the proposed system reflects their age and individual interesting per each e-learning stage. This system supports both the Web application platform and smart phone application platform for various client requirements. The proposed system manages 3 classes as English learning content. Learners can experience their own English e-learning course in each class, which is compiled by current educational ability. In addition to the general functions in e-learning system, the proposed system develops content buffering algorithm to reduce data traffic in server.

• Journal of Practical Engineering Education
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• v.9 no.2
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• pp.133-137
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• 2017

In this paper, we present the results of the study on the development of electric circuit e-learning content as one of the required courses in electrical and electronics engineering. Theoretical learning of electric circuit e-learning contents is based on multimedia type and the practice part is based on moving picture. The e-learning contents were used for a blended learning in actual offline class. We investigated the learning effect of each component of e-learning contents and investigated and analyzed the type of e-learning contents suitable for class of electric circuit. In addition, we investigated and analyzed effective ways to utilize e-Learning content for offline teaching. In this paper, we show how to construct effective contents, length types and utilization methods in engineering education through the case study on the e-learning content.

• Current Optics and Photonics
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• v.1 no.3
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• pp.207-213
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• 2017

The Adaptive Front-lighting System (AFS) is a part of the active safety system, providing optimized vision to the driver during night time and other poor-sight conditions of the road by automatic adaptation of lighting to environmental and traffic conditions. Basically, an AFS provides four different modes of the passing beam as designated in an United Nations Economic Commission for Europe regulation (ECE324-R123): neutral state or country light (Class C), urban light (Class V), highway light (Class E), and adverse weather light (Class W). In this paper, we first present an optics design for an AFS system capable of producing the Class C/V/E/W patterns requiring only on/off modulation of multi-array LEDs with no need for any additional mechanical components. The AFS optics consists of two separated modules, cutoff and spread; the cutoff module lights a narrow central area with high luminous intensity, satisfying the cutoff regulation, and the spread module forms a wide spread beam of low luminous intensity. Each module consists of two major parts; the first converts a discretely positioned LED array into a full-filled area emitting light source plane, and the second projects the light source plane to a 25 m away target plane. With the combination of these two optics modules, the four beam patterns are formed by simple on/off modulation of multi-array LEDs. Then we report the development of a prototype that was demonstrated to provide the four beam patterns.

• Parasites, Hosts and Diseases
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• v.62 no.2
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• pp.205-216
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• 2024

Sigma-class glutathione transferase (GST) proteins with dual GST and prostaglandin synthase (PGS) activities play a crucial role in the establishment of Clonorchis sinensis infection. Herein, we analyzed the structural and enzymatic properties of sigma-class GST (CsGST-σ) proteins to obtain insight into their antioxidant and immunomodulatory functions in comparison with mu-class GST (CsGST-µ) proteins. CsGST-σ proteins conserved characteristic structures, which had been described in mammalian hematopoietic prostaglandin D₂ synthases. Recombinant forms of these CsGST-σ and CsGST-µ proteins expressed in Escherichia coli exhibited considerable degrees of GST and PGS activities with substantially different specific activities. All recombinant proteins displayed higher affinities toward prostaglandin H₂ (PGS substrate; average K_m of 30.7 and 3.0 ㎛ for prostaglandin D₂ [PGDS] and E₂ synthase [PGES], respectively) than those toward CDNB (GST substrate; average K_m of 1,205.1 ㎛). Furthermore, the catalytic efficiency (K_cat/K_m) of the PGDS/PGES activity was higher than that of GST activity (average K_cat/K_m of 3.1, 0.7, and 7.0×10^-3 s^-1㎛^-1 for PGDS, PGES, and GST, respectively). Our data strongly suggest that the C. sinensis sigma- and mu-class GST proteins are deeply involved in regulating host immune responses by generating PGD₂ and PGE₂ in addition to their roles in general detoxification.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.77.1-77.1
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• 2015

We present our recent work published in the MNRAS (Lee and Kim, 2014). Numerical studies of the imaging and caustic properties of the singular isothermal sphere (SIS) under a wide range of external shear (from 0.0 to 2.0) are presented. Using a direct inverse mapping formula for this lensing system, we investigate various lensing properties for both low-shear (i.e. ${\gamma}$<1.0) and high-shear (i.e. ${\gamma}$ >1.0) cases. We systematically analyse the effective lensing cross-sections of double-lensing and quadruple-lensing systems, based on the radio luminosity function obtained by the Jodrell-VLA Astrometric Survey (JVAS) and the Cosmic Lens All-Sky Survey (CLASS). We find that the limit of a survey selection bias (i.e. between brighter and fainter images) preferentially reduces the effective lensing cross-sections of two-image lensing systems. By considering the effects of survey selection bias, we demonstrate that the long-standing anomaly over the high quads-to-doubles ratios (i.e. 50~70 % for JVAS and CLASS) can be explained by the moderate effective shear of 0.16~0.18, which is half that of previous estimates. The derived inverse-mapping formula could make the SIS + shear lensing model useful for galaxy-lensing simulations.

• The Korean Journal of Applied Statistics
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• v.32 no.5
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• pp.683-692
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• 2019

It is hard to imagine teaching statistics without the help of technology. Technology is changing the way in which the content of introductory statistics is taught and the forms of textbook used. Almost all students carry mobile devices all the time that allows them to learn anytime and anywhere if we provide them with statistical electronic textbook. The use of smartphones for asking questions and finding answers in class, it can encourage students to engage more in lectures. This paper analyzes the data obtained using e-textbook in traditional classroom and discusses the future research direction of e-textbooks.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.1
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• pp.1-6
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• 2008

Performance test of the 30-ton class liquid rocket engine turbopump turbine has been conducted using high pressure cold air. Overall performance of the two kinds of turbine rotors - rotor with knife-edged L.E blades and with rounded L.E blades - has been measured for various rotational speed and turbine pressure ratio. The effect of rotational speed and turbine pressure ratio on the turbine axial force behavior also has been measured in parallel. Test results have revealed that the efficiency of knife edged L.E. turbine is a little bit higher than that of rounded L.E. turbine. The axial force of the turbine varied linearly with respect to rotational speed and its magnitude largely depended on turbine pressure ratio.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.21-24
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• 2008

We have developed a $kW_e$ class liquid fuel based solid oxide fuel cell (SOFC) system. Our final target is to develop the 1 $kW_e$ diesel based SOFC system for residential power generator(RPG). In this study, we present the conceptual design of SOFC system. System is composed of hot-box and cold-box. Planar typed SOFC stack, heat exchanger, combustor for stack tail gas, and fuel processor, such as fuel reformer and desulfurizer, are contained in the hot-box. And several balance of plants(BOP), such as fuel suppliers and controller, are contained in the cold-box. Before the SOFC system fabrication, we have already operated the selfsustaining fuel processor, and heat exchange of all heat-related components is simulated using ASPEN HYSYS, because heat maintenance and management in hot-box are important for stable operation of SOFC system. The self-sustained fuel processor was successfully operated for about 250 hours, and heat exchange is enough to operate the SOFC system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.9
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• pp.3421-3443
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• 2021

A data hiding method based on integer factorization via e-books in the EPUB format with XHTML and CSS files for copyright protection is proposed. Firstly, a fixed number m of leading bits in a message are transformed into an integer which is then factorized to yield k results. One of the k factorizations is chosen according to the decimal value of a number n of the subsequent message bits with n being decided as the binary logarithm of k. Next, the chosen factorization, denoted as a × b, is utilized to create a combined use of the

and elements in the XHTML files to embed the m + n message bits by including into the two elements a class selector named according to the value of a as well as a text segment with b characters. The class selector is created by the use of a CSS pseudo-element. The resulting web pages are of no visual difference from the original, achieving a steganographic effect. The security of the embedded message is also considered by randomizing the message bits before they are embedded. Good experimental results and comparisons with exiting methods show the feasibility of the proposed method for copyright protection of e-books.