• Journal of Computing Science and Engineering
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• v.4 no.1
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• pp.80-95
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• 2010

In order to truly integrate e-Learning system into regular curriculum at a university, mobile access to Learning Management Systems has to be enabled. Mobile devices have the potential to be integrated into the classroom, because they contain unique characteristics such as portability, social interactivity, context sensitivity, connectivity and individuality. Adoption of Learning Management Systems by students is still on the low rate, mostly because of poor usability of existing e-Learning systems. Our initial research has confirmed this hypothesis. Usability issue is rising to the higher level on the mobile platform, because of the mobile devices' limited screen size, input interfaces and bandwidth, and also because of the context of use. Our second hypothesis was that it is wrong to consider a mobile device as a surrogate for desktop or laptop personal computer (PC). By just adopting the existing Learning Management System on mobile devices with adaptive technologies such as Google proxy, we do not acquire the satisfactory results. Usability can prove to be even lower compared to desktop application. One possible solution to the problem could be development of rich client applications for today's mobile devices that would raise the usability to a higher level. We developed a PocketPC prototype application by using user-centered design principles, which we presented as a third alternative in usability research conducted among university students. Results gathered in such a way have confirmed that development of e-Learning system, in order to be widely accepted by students, needs to have the user(student) in the center of development process.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.10
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• pp.946-951
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• 2011

This paper presents the simulation results of GBAS availability and requirement (with respected to Vertical Protection Level) using simulated data at CAT I, CAT II/III DH point (Decision Height), which are generated using Jeju international GNSS reference position, aircraft horizontal velocity and reference/aircraft GNSS antenna performance index and so on. Two kinds of protection levels are presented, one is from a hypothesis (H0) and other is from a alternative hypothesis (H1). These protection levels are compared with AL (Alert Limit), and we analyse the GBAS availability and requirement for CAT I and CAT II/III at the airport.

• The Korean Journal of Applied Statistics
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• v.25 no.2
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• pp.311-319
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• 2012

The simplest and the most important distribution in survival analysis is exponential distribution. Koziol and Green (1976) derived Cram$\acute{e}$r-von Mises statistic's randomly censored version based on the Kaplan-Meier product limit estimate of the distribution function; however, it could not be practical for a real data set since the statistic is for testing a simple goodness of fit hypothesis. We generalized it to the composite hypothesis for exponentiality with an unknown scale parameter. We also considered the classical Kolmogorov-Smirnov statistic and generalized it by the exact same way. The two statistics are compared through a simulation study. As a result, we can see that the generalized Koziol-Green statistic has better power in most of the alternative distributions considered.

• Journal of Korean Society for Geospatial Information Science
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• v.7 no.1 s.13
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• pp.29-40
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• 1999

In vector GIS, natural linear entities (called linear entitles) are usually represented by a set of line segments. As an alternative of the line segments, curve segments can be used to represent the linear entities. The curve segments, as one-dimensional spatial objects, we generated by spline interpolation technique such as Bezier technique. In an effort to improve its accuracy in resembling the linear entities, the Bezier technique was modified generating a new technique (called New technique) (Kiyun, 1998). In this paper, validity of the New technique was tested. Test focused on answering two questions: (1) whether or not the curve segments from the New technique replace line segments so as to enhance the accuracy of representations of linear entities, and (2) whether or not the curve segments from the New technique represent the linear entities more accurately than curve segments from the Bezier technique. Answering these two questions entailed two hypothesis tests. For test data, a series of hydrologic lines on 7.5-minute USGS map series were selected. Test were done using t-test method and statistical inferences were made from the results. Test results indicated that curve segments from both the Bezier and New techniques represent the linear entities more accurately than the line segments do. In addition, curve segments from the New technique represent the linear entities more accurately than the line segments from the Bezier technique do at probability level 69% or higher.

• KDI Journal of Economic Policy
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• v.27 no.2
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• pp.123-154
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• 2005

Using Korean household data, this paper examines how consumption of durable goods is determined. Previous studies report that the standard Permanent Income Hypothesis (PIH), while being broadly consistent with non-durable goods consumption, provides little explanation for durable goods consumption. In this paper, we consider the (S, s) model as an alternative to the standard PIH. The (S, s) model predicts that, because of fixed adjustment costs, consumers make no adjustment to the durable goods stock until deviation from the optimal level becomes large. When the adjustments are made, the durable goods stock attains the optimal level. In order to test this prediction, we examine the intra-temporal relationship between non-durable goods and durable goods consumption and intertemporal changes in durable goods consumption, using data from the Korean Household Panel Study. The results show that, while the standard PIH is rejected by the data, the (S, s) model is not.

• Environmental Engineering Research
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• v.11 no.4
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• pp.217-231
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• 2006

The gas-phase formation of polychlorinated naphthalenes (PCNs) and dibenzofurans (PCDFs) was experimentally investigated by slow combustion of the three chlorophenols (CPs): 2-chlorophenol (2-CP), 3-chlorophenol (3-CP) and 4-chlorophenol (4-CP), in a laminar flow reactor over the range of 550 to $750^{\circ}C$ under oxidative condition. Contrary to the a priori hypothesis, different distributions of PCN isomers were produced from each CP. To explain the distributions of polychlorinated dibenzofuran (PCDF) and PCN congeners, a pathway is proposed that builds on published mechanisms of PCDF formation from chlorinated phenols and naphthalene formation from dihydrofulvalene. This pathway involves phenoxy radical coupling at unsubstituted ortho-carbon sites followed by CO elimination to produce dichloro-9, 10-dihydrofulvalene intermediates. Naphthalene products are formed by loss of H and/or Cl atoms and rearrangement. The degree of chlorination of naphthalene and dibenzofuran products decreased as temperature increased, and, on average, the naphthalene congeners were less chlorinated than the dibenzofuran congeners. PCDF isomers were found to be weakly dependent to temperature, suggesting that phenoxy radical coupling is a low activation energy process. Different PCN isomers, on the other hand, are formed by alternative fusion routes from the same phenoxy radical coupling intermediate. PCN isomer distributions were found to be more temperature sensitive, with selectivity to particular isomers decreasing with increasing temperature.

• Korean Institute of Interior Design Journal
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• v.15 no.6 s.59
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• pp.77-88
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• 2006

According to critics and architects, non-linear structure is not only an organic form of space, but also a form of space detached from modem style. Accordingly, non-linear structure can be accepted as an alternative to what has remained unsolved by deconstructionist. However, they are criticized for not clarifying the interdependent relationship between non-linearity of space and cognitive structure of human being. They ended up remaining the hypothesis just an intuitive and abstract one. This research began on the basis that their hypothesis is hard to be objectified, and it needs further inquiry. The purpose of this thesis is to explore how the redundant factors constitute non-linear structures of digital media centered space design. Geometric compositions of space structure were analyzed to define what types of redundant factors are contrived in the process of visual information. This study about the visual form, researching the Information Theory, and then offer a quantitative analysis that makes those more objective. Space structure and geometric composition were analyzed to define what types of redundancy are contrived in the process of visual information. In particular, I put higher theoretical emphasis on what characteristics are ensued in the process of structuring spaces than any other subjects. Followings are the conclusion of analysis. First, as a result of examining, we can assume that NOX' space structure is not a chaotic form, but has an operating the form of its own. Second, in case of curvilinear, the structure was found redundancy on mid deviation ratio and discontinuous circular fabric. Although most of their structures appeared complex with a higher coherent constant, they were found to be stable factors because of the low deviation ratio between systems. The amount of surplus information was stable structure as well.

• Archives of design research
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• v.15 no.3
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• pp.241-248
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• 2002

Researches of Hangul automation have been focused mainly on the set of character system. But, practical problem of using the Korean standard keyboard system of two sets is increment of errors and fatigue due to frequent use of shift keys. The author formulate a hypothesis as follows to solve the problem. 'Changing location and design of shift keys can reduce errors in typing Korean by avoiding interferences with other keys when pressing shift keys.' This study verify the hypothesis by the analysis of experiments using improved keyboard prototypes which have changed layout and design of shift keys. On the result, change of shift key location causes confusion to experienced user. But, while keeping its location, removing other keys at the bottom row and magnifying size of shift keys decrease errors in typing by avoiding interferences. And, the efficiency of typing in Korean is increased, too, because there is not any influence on typing speed. This study focuses on layout and design of shift keys only, but further study for entire layout of keyboard including alternative location of other function keys is needed to improve general usability.

• Korean Journal of Cognitive Science
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• v.24 no.2
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• pp.111-132
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• 2013

Previous research has shown that aging asymmetrically affects various functions in language. It is known that older adults show deficits in language production compared to young adults, while the performance in semantic processing is similar between older and young adults. The tip-of-the-tongue (TOT) phenomenon effectively reflects failure in retrieval of phonological knowledge. Older adults report TOTs more often than young adults and the cause of this phenomenon has been explained by two frameworks: the 'blocking hypothesis' and 'transmission deficit hypothesis'. This study examines the effect of aging on the retrival of phonological knowledge by inducing TOTs in the laboratory. Two variables were manipulated: age and word category. Participants were young and older adults, and stimuli was selected from 5 categories of words. After the participants read a definition about a target word, they reported three conditions: 'know', 'don't know', 'TOT'. The results were as follows: First, the older adults reported TOTs more often than the young adults. Second, TOTs occurred more in proper nouns such as names of persons and places. Third, in the category that TOTs occurred more often, there was a bigger age difference. Fourth, older adults reported fewer alternative words during TOT than young adults. Fifth, participants tended to report the partial information during TOT in characters. These results show the age-related difficulty in the retrieval of phonological knowledge in Korean. It is explained by the transmission deficit hypothesis and the characteristics of Korean orthography and phonology.

• Korean Journal of Cognitive Science
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• v.24 no.4
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• pp.365-391
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• 2013

Negative repetition effect (NRE) refers to the phenomenon that the accuracy of report is impaired when a target was flanked by the same distractor than when by alternative distractor. To probe the nature of NRE, this study introduced attention window(s) indicating the positions where a target might be presented, and non-attention window(s) where a target could not be presented. Attention windows are supposed to help participants detect targets readily. Two among three positions are indicated by attention windows in Exp. 1, and a single large attention window encompassing central two positions among four positions was used in Exp. 2, and either large or small attention window was used depending on the number of target candidates in Exp. 3. In the result of three experiments, NREs were consistently observed when both positions of a target and a distractor were indicated by previous attention windows. However, NREs (including its tendency) and its opposite, PREs were observed when a distractor was presented in the non-attention position, depending on its distance from the target and the size of attention window. It seems that this pattern of repetition effects is hard to be explained by repetition blindness hypothesis (Kanwisher, 1991), positional uncertainty hypothesis (Keren & Boer, 1985), and inhibitory attention capture hypothesis (Kwak et al., 1993). Instead it was proposed that shifting of spatial attention should be considered accordingly with the structure of stimulus display. The promising role of this task was discussed in studying the relation of attention and perception.