• Communications for Statistical Applications and Methods
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• v.23 no.2
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• pp.93-103
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• 2016

In the paper, we discuss dimension reduction of predictors ${\mathbf{X}}{\in}{{\mathbb{R}}^p}$ in a regression of $Y{\mid}{\mathbf{X}}$ with a notion of sufficiency that is called sufficient dimension reduction. In sufficient dimension reduction, the original predictors ${\mathbf{X}}$ are replaced by its lower-dimensional linear projection without loss of information on selected aspects of the conditional distribution. Depending on the aspects, the central subspace, the central mean subspace and the central $k^{th}$-moment subspace are defined and investigated as primary interests. Then the relationships among the three subspaces and the changes in the three subspaces for non-singular transformation of ${\mathbf{X}}$ are studied. We discuss the two conditions to guarantee the existence of the three subspaces that constrain the marginal distribution of ${\mathbf{X}}$ and the conditional distribution of $Y{\mid}{\mathbf{X}}$. A general approach to estimate them is also introduced along with an explanation for conditions commonly assumed in most sufficient dimension reduction methodologies.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.4
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• pp.489-496
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• 2010

In this paper, a self-organization framework for swarm systems in three dimensions is presented. The framework uses artificial potential functions(APFs) to direct the robots toward the goal as well as to keep them in a swarm system. This research extends conventional APFs used for self-organizations in two dimension environment to three dimensions. In three dimension environment, the ground potential for the boundary surfaces that commonly appear in three dimension environments is proposed. Accordingly, the comparison between the paths without and with the ground potentials shows the necessity and effect of ground potentials. Extensive simulations are given to show the effectiveness of the extended potentials and various properties in three dimension environments.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.255-259
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• 2003

Moire topography method isa well-known non-contacting 3-D measurement method as afast non-contact test for three-dimension shape measuring method. Recently, it's important to study the automatic three-dimension measurement by moire topography because it is frequently applied to the reverse engineering , the medical , the entertainment fields. Three-dimension measurement using projection of moire topography is very attractive because of its high measuring speed and high sensitivity. In this paper, the classical moire method is computerized-so called digital moire when a virtual grating pattern is projected on a surface, the captured image by the CCD camera has three-dimension information of the objects. The moire image can be obtained through a simple image processing and a reference grating pattern. and it provides similar results without physical grating pattern. digital projection moire topography turn out to be very effective for the three-dimension measurement of objects. Using different N-bucket algorithm method of digital projection moire topography is tested to measuring object with the 2-ambiguity problem. Experimental results prove that the proposed scheme is capable of finding measurement errors that decreased more by using the four-three step algorithm method instead of the same step in the phase shifting of different pitch.

• Communications for Statistical Applications and Methods
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• v.31 no.5
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• pp.521-533
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• 2024

As the concentration of fine dust has recently increased, numerous related studies are being conducted to address this issue. Aerosol optical depth (AOD) is a vital atmospheric parameter for measuring the optical properties of aerosols in the atmosphere, providing crucial information related to fine dust. In this paper, we apply three dimension reduction methods, nonnegative matrix factorization (NMF), empirical orthogonal functions (EOF) analysis and independent component analysis (ICA), to AOD data to analyze the patterns of fine dust in the East Asia region. Through a comparison of three dimension reduction methods, we observe that some patterns are observed in all three method, while some information are only extracted in a specific method. Additionally, we forecast AOD levels based on three methods, and compare the predictive performance of the three methodologies.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.3
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• pp.47-55
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• 1997

A vacation destination was conceptualized to be chosen through a three-stage process consisting of an early consideration set formation, a late consideration set formation, and a final selection stage. Choice criteria were defined as an individual's belief toward the relationships between perceived attributes, expected outcomes, and the destination. And these criteria were assumed to be divided into benefit-related dimension and perceived risk-related dimension. Through two pilot surveys, 13 items which have 4 factors were identified. used on 4 factor structures, the benefit-related dimension was identified to be consisted of three sub-dimensions, "historic/cultural", "escaped" and "naturalness". A longitudinal panel survey was used to test the differences of the importance of choice dimensions through the choice process. The importance of benefit-related dimension was decreased through the choice process as hypothesized except "naturalness" factor. And as hypothesized, the importance of perceived risk-related dimension was increased.

• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.209-215
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• 2006

A closely associated set of characteristics was analyzed using both classical and truss dimensions to discriminate the morphometric traits of three species of torrent catfish (Amblycipitidae) in Korea. After arcsine square root transformation, 18 measurements relative to the standard length and three measurements relative to the head length of each species of torrent catfish were compared statistically. Classical and truss dimensions of each of four morphometric traits showed higher values in the bullhead torrent catfish, Liobagrus obesus, than the Korean and south torrent catfish (L. andersoni and L. mediadiposalisa, respectively; P<0.05). Truss dimensions of three morphometric traits were higher in the bullhead and Korean torrent catfish than in the south torrent catfish (P<0.05). There were no significant differences in six morphometric traits among these Amblycipitidae. The dimensions used in this study may be useful as taxonomic indicators to discriminate species of Liobagrus in Korea.

• The Research Journal of the Costume Culture
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• v.11 no.2
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• pp.219-230
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• 2003

The purpose of this study was to analyze the structure of consumption emotions that consumers experienced in the process of consuming apparel products. Data was collected from 144 female college students living in Busan, and analyzed by salience, diversity, H-index, Clamor's V, and multi-dimensional scaling. The results showed as following; 1. The consumption emotions related to apparel products appeared three dimensions; ‘Relaxed-tense’ dimension, ‘Pleasant-unpleasant’ dimension, and ‘Outward-inward’ dimension. Considering elements of consumption system, the dimensions of consumption emotions in relation to apparel performances were 'Pleasant-unpleasant' and ‘Outward-inward’. The dimensions of consumption emotions experienced in usage situations were ‘Relaxed-tense’ and ‘pleasant-unpleasant’. The consumption emotions related to specific products were composed of ‘Pleasant-unpleasant’ dimension and ‘Outward-inward’ dimension. 2. As the multi-dimension map of this study has much space, it suggested that the scope of consumption emotions related to apparel products was more limited than those related to general situations and products. 3. The structure of consumption emotions in relation to apparel performances appeared to be bisected, while those related to usage situations showed relatively to be dispersed. 4. Although Pleasant-unpleasant dimension was consistent with results of prestudies, the dimensions of ‘Relaxed-tense’ and ‘Outward-inward’ were newly confirmed as the dimensions of consumption emotions related to apparel products. Therefore, consumer's consumption emotions of apparel products were composed of three dimensions, tended to be more limited than those of general consumption situations and products, and differentiated across apparel performances, usage situation, and specific products.

• The Journal of Asian Finance, Economics and Business
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• v.6 no.1
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• pp.177-185
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• 2019

Service quality is still a new concept to those who works in shipping lines services since it has not been identified as a mandatory factor to increase competitiveness. Most carriers are currently offering services at the same level of price, transit time, equipment, etc. Thus offering a high quality service is the best way for a carrier to differentiate itself from its competitors in the market. The research aims to conduct an assessment on service quality at Wan Hai Lines (WHL) outbound services based on the SERVQUAL model, form of dimension-by-dimension analysis. This study was based on a survey of 135 people. The outcome is the service quality of WHL outbound services can be identified by three dimension(s): Empathy and Responsiveness, Assurance, and Reliability. It would help management to have an overall picture about the current service quality, and to find solutions to improve service quality following the recommendations. WHL managers need to recognize that "Reliability" has the strongest influence on customers' expectations, then come "Empathy and Responsiveness" and "Assurance". Therefore, board of managers should spend time looking carefully at each of the three dimensions, especially for the biggest gap between perceptions and expectations of three dimensions as well. Then the recommendations were raised.

• Korea Trade Review
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• v.46 no.2
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• pp.75-92
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• 2021

There is increasing awareness in the international alliance literature that the firm performance effects of the alliance portfolio go beyond the effects of the individual alliances. I enrich this nascent perspective by developing a alliance portfolio composition framework based on the alliance portfolio dimensions - underpinned by the simultaneity of quantitative and qualitative factors in international portfolio - that enhances firms' financial performance. This paper assesses the impact on firm performance of composing the alliance dimension within a firm's international alliance portfolio. In an unbalanced panel data analysis with fixed effects of the performance of 502 firms operating in the Korean manufacturing industry during 2011-2017, I test whether firm's three dimension of international alliance portfolio affect on firm financial performance. I find that the intensity of international alliance have significantly positive effect on the firm performance. And following the moderating analysis of three portfolio dimension-functional, relational, and attribute, all of each three international alliance portfolio has positive moderating effects on the relationship between the alliance intensity and firm performance. These results indicate that firms should consider and form simultaneous approaches to exploit the international alliance based on the alliance portfolio dimensions with intensity of alliance portfolio.

• Proceedings of the Korea Society of Design Studies Conference
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• 2005.05a
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• pp.222-223
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• 2005