• Journal of the Korean Society of Groundwater Environment
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• v.4 no.3
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• pp.122-129
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• 1997

Spills or leaks of hazardous organic. compounds from underground storage tanks (USTs) are common contaminant sources of soil and groundwater. It would aid in managing USTs to assess and rank the potential environmental hazard posed by the USTs. Therefore, a preliminary hazard ranking system of USTs is developed in this study. The system is combined with GIS and consists of five steps: 1) selection of significant factors, 2) determination of the hierarchy of the factors. 3) determination of the weights, 4) calculation of the potential hazard, and 5) hazard assessment. The system is applied to the gas stations in Kwanak-gu, Seoul. The results indicate that the gas stations can be categorized in three groups as highly hazardous, less highly hazardous, and weakly hazardous. Seven gas stations belong to the highly hazardous group. Through the sensitivity analysis, four stations appear to possess high hazard potentials regardless of weights assigned to the factors. It appears that a user can make flexible application of the hazard ranking system with the user's experience and particular purposes. However, the system still needs validations against field survey data.

• The Journal of the Korea Contents Association
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• v.17 no.10
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• pp.179-189
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• 2017

The purpose of this paper is to develop a comprehensive research model that can explain potential customers' intentions to adopt and use VPA(Virtual Personal Assistants) devices. This study proposes and validates a new theoretical model that extends the perceived value theory. Partial least squares analysis is employed to test the research model and corresponding hypotheses on data collected from 313 survey samples. Perceived value, perceived usefulness, perceived enjoyment are important factors affecting the adoption of VPA devices. To increase potential users' intention to use, VPA device manufacturers should not only focus on developing utilitarian functions but also fun features based on open development echo-system. This study is the important empirical attempt to examine user acceptance of VPA devices, as most of the prior literature has concerned analysis of usage patterns or technical features.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.27 no.3
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• pp.188-195
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• 2016

Objectives: The aim of this study was to investigate the relationship between internet addiction, smartphone addiction, and psychosocial factors. This study was designed to examine the vulnerability factors for internet and smartphone addiction. Methods: The participants were 1041 children and adolescents in a small and medium-sized cities. All of the participants were evaluated in terms of their demographic characteristics and present use of the internet and smartphone, as well as using internet and smartphone addiction and other psychological scales. Statistical analyses were performed to compare the psychosocial factors between the high risk, potential risk, and general user groups of internet and smartphone addiction. Results: The participants were classified into three groups, the high risk (N=33), potential risk (N=203), and general user (N=805) groups with regard to their internet and smartphone addiction level. There were statistical significantly differences between the groups in terms of the economic status of the family, academic performance, parents, use of internet and smartphone, loneliness, family cohesion, family adaptability, perceived social support, and peer relationship. Conclusion: These results suggest that the internet and smartphone addiction of children and adolescents is related to various psychosocial vulnerability factors.

• International journal of advanced smart convergence
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• v.9 no.2
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• pp.90-104
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• 2020

It is difficult for non-experts to build machine learning (ML) models at the level that satisfies their needs. Deep learning models are even more challenging because it is unclear how to improve the model, and a trial-and-error approach is not feasible since training these models are time-consuming. To assist these novice users, we examined how interactive and explainable feedback while training a deep learning network can contribute to model performance and users' satisfaction, focusing on the data preparation process. We conducted a user study with 31 participants without expertise, where they were asked to improve the accuracy of a deep learning model, varying feedback conditions. While no significant performance gain was observed, we identified potential barriers during the process and found that interactive and explainable feedback provide complementary benefits for improving users' understanding of ML. We conclude with implications for designing an interface for building ML models for novice users.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.454-458
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• 2007

Nonpoint source (NPS) pollution is a serious problem causing the degradation of soil and water quality. Concentrated overland flow is the primary transport mechanism for a large amount of NPS pollutants from hillslope areas to downslope areas in a watershed. In this study, a soil erosion model, nLS model, to identify transitional overland flow regions (i.e., ephemeral gully head areas) was developed using the kinematic wave overland flow theory. Spatial data, including digital elevation models (DEMs), soil, and landcover, were used in the GIS-based model algorithm. The model was calibrated and validated using gully head locations in a large agricultural watershed, which were identified using 1-m aerial photography. The model performance was better than two previous approaches; the overall accuracy of the nLS model was 72 % to 87 % in one calibration subwatershed and the mean overall accuracy was 75 to 89 % in four validation subwatersheds, showing that the model well predicted potential transitional erosion areas at different watersheds. However, the user accuracy in calibration and validation was still low. To improve the user accuracy and study the effects of DEM resolution, finer resolution DEMs may be preferred because DEM grid is strongly sensitive to estimating model parameters. Information gained from this study can improve assessing soil erosion process due to concentrated overland flow as well as analyze the effect of microtopographic landscapes, such as riparian buffer areas, in NPS control.

• Journal of Korea Multimedia Society
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• v.8 no.10
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• pp.1306-1313
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• 2005

Relevance Feedback(RF), a method to use perceptual feedback in image retrieval, refines a query by the relevance information from a user. However, the user's feedback information is thrown away as soon as a search session ends. So, this paper proposes an enhanced version of RF, which is designed to accumulate human perceptual responses over time through relevance feedback and to dynamically combine the accumulated high-level relevance information with low-level features to further improve the retrieval effectiveness. Experimental results are presented to prove the potential of the proposed RF.

• ETRI Journal
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• v.39 no.2
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• pp.234-244
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• 2017

Research interest in three-dimensional multiple-input multiple-output (3D-MIMO) beamforming has rapidly increased on account of its potential to support high data rates through an array of strategies, including sector or user-specific elevation beamforming and cell-splitting. To evaluate the full performance benefits of 3D and full-dimensional (FD) MIMO beamforming, the 3D character of the real MIMO channel must be modeled with consideration of both the azimuth and elevation domain. Most existing works on the 2D spatial channel model (2D-SCM) assume a wide range for the distribution of elevation angles of departure (eAoDs), which is not practical according to field measurements. In this paper, an optimal FD-MIMO planar array configuration is presented for different practical channel conditions by restricting the eAoDs to a finite range. Using a dynamic network level simulator that employs a complete 3D SCM, we analyze the relationship between the angular spread and sum throughput. In addition, we present an analysis on the optimal antenna configurations for the channels under consideration.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.7 no.1
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• pp.231-246
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• 1994

A major problem for information retrieval research in the past three decades has been methodology, even though some progress has been made in obtaining useful results from methodologically sound experiments. Within a methodology, potential problems include artificial data generated by the researcher, small sample size interpretation of findings. Critics have pointed out that some room exists for improving methodology of information retrieval research; using existing data, having big enough sample size, including large numbers of search queries, introducing more control in relation to variables, utilizing more appropriate performance measures, conducting rests carefully and evaluating findings properly. Relevance judgments depend entirely on the perception of the user and on the situation of the moment. In an experiment, the best judge of relevance is a user with a well defined information need. Normally more than two categories for relevance judgments are desirable becase there are degrees of relevance. In experimental design, careful control of variables is meeded for internal validity. When no single database exists for comparison, existing operational databases should be used cautiously, Careful control for the variations of search queries, inter-searcher sonsistency, intra-searcher consistency and search strategies is necessary. Parametric statistics requiring rigid assumptions are not appropriate in information retrieval research and non-parametric statistics requiring few assumptions are necessary. Particularly, the sign test and the Wilcoxon test are good alternatives.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.7
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• pp.2365-2382
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• 2014

While single-user spatial multiplexing multiple-input multiple-output (SU-MIMO) allows spatially multiplexed data streams to be transmitted to one node at a time, multi-user spatial multiplexing MIMO (MU-MIMO) enables the simultaneous transmission to multiple nodes. However, if the transmission time required to send packets to each node varies considerably, MU-MIMO may fail to utilize the available MIMO capacity to its full potential. The transmission time typically depends upon two factors: the link quality of the selected channel and the data length (packet size). To utilize the cumulative capacity of multiple channels in MIMO applications, the assignment of channels to each node should be controlled according to the measured channel quality or the transmission queue status of the node.A MAC protocol design that can switch between MU-MIMO and multiple SU-MIMO transmissions by considering the channel quality and queue status information prior to the actual data transmission (i.e., by exchanging control packets between transmitter and receiver pairs) could address such issues in a simple but in attractive way. In this study, we propose a new MAC protocol that is capable of performing such switching and thereby improve the system performance of very high throughput WLANs. The detailed performance analysis demonstrates that greater benefits can be obtained using the proposed scheme, as compared to conventional MU-MIMO transmission schemes.

• Smart Media Journal
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• v.9 no.4
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• pp.73-80
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• 2020

With the advent of the Internet era, consumer lifestyles have been changed tremendously, and mobile payment has carried out an increasingly extensive coverage of the people's life trajectory. Taking the design of the mobile payment interface as an example, we use a conjoint analysis method to survey college students in Guangxi, where questionnaires are collected from 270 people in different groups according to gender. The method separates the attributes that affect consumer choice of mobile payment interface design and the utility value of the attribute level to analyze consumer needs and preferences, and then obtains consumers' potential evaluation criteria for mobile payment interface design. The results of the study show that the attributes that influence consumers' choice of mobile payment interface design are, in order of preference: page layout, identification convenience, verification, module distribution, entertainment, and information encryption. Consumer groups of different genders show differences in their preferences in the mobile payment interface design and Consumer needs reflect consumer psychology. Several findings are obtained on the consumers' preferences on the mobile payment interface design, which may be used to improve future design processes.