• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.1
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• pp.67-78
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• 2005

We proposed a blind watermarking for 3D mesh model using the patch CEGIs. The CEGI is the 3D orientation histogram with complex weight whose magnitude is the mesh area and phase is the normal distance of the mesh from the designated origin. In the proposed algorithm we divide the 3D mesh model into the number of patch that determined adaptively to the shape of model and calculate the patch CEGIs. Some cells for embedding the watermark are selected according to the rank of their magnitudes in each of patches after calculating the respective magnitude distributions of CEGI for each patches of a mesh model. Each of the watermark bit is embedded into cells with the same rank in these patch CEGI. Based on the patch center point and the rank table as watermark key, watermark extraction and realignment process are performed without the original mesh. In the rotated model, we perform the realignment process using Euler angle before the watermark extracting. The results of experiment verify that the proposed algorithm is imperceptible and robust against geometrical attacks of cropping, affine transformation and vertex randomization as well as topological attacks of remeshing and mesh simplification.

• Korean Journal of Ichthyology
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• v.13 no.1
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• pp.32-39
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• 2001

Surf-zone fishes in Daechon Beach, situated at the mouth of Cheonsu Bay, Korea, were collected by a beach seine during the spring and neap tides in August 1999. Short-term variation in species composition was analyzed based on tidal range, tidal level, and time of day. Of 24 species identified, juvenile pelagic fishes predominated in the number of individuals captured. Wilcoxon signed-rank test revealed that the number of individuals was significantly higher during the spring tide than during the neap tide. During the spring tide the fishes were more abundant at the low level than at the high level, while during the neap tide there was no significant difference. The mean density of pelagic fishes did not show significant differences between high and low tides. Demersal fishes were caught mainly in the water below the low level of the neap tide.

• Journal of the Korean School Mathematics Society
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• v.19 no.2
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• pp.177-196
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• 2016

In this paper, we analyze the influence of mathematics teaching-learning for high level math problems of A-type of mathematics section on the College Scholastic Ability Test(CSAT). To analyze the influence, we compare and analyze units and field of questions set at examinations based on the rate of wrong answers in A-type mathematics test of the CSAT from 2012 to 2016. Also, we study the recognition of academic high school students and teachers about units and fields on math which need to allow more time to improve grade for A-type of mathematics section on the CSAT. We found following facts. First, high level math problems determining rank of high rank students on the CSAT was taken mostly from the unit related a exponential function and a logarithmic function. Second, these problems need more time for a calculation rather than an ability for students to deepen their understanding of the concept and quality of education. Third, high rank students spend a lot of time to study more important units and fields of mathematics on the CSAT such as a exponential function and a logarithmic function, and teachers spend a lot of time to teach them.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.2 s.36
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• pp.77-88
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• 2006

Overpopulation has been one of the most serious problem of the Seoul Metropolitan Area (SMA), which consists of the City of Seoul, Incheon, and the whole of Gyeonggi Province. People have been still moving into SMA, especially being concentrated into the fringe of Seoul. This study examines the inner city decline phenomenon of SMA which can be easily found in large cities over the world, based on the demographic data of these area. In addition, this study monitors the imbalance in growing of SMA by analyzing RMI (Rank Mobility Index), and the inverse relation between the self sufficiency of the adjacent area and the commuting rate to Seoul by analyzing commuting data. Even though the total population has been unchanged, the internal change of population was substantial. The growth of Seoul Metro region was placed near the city of Seoul, especially commuter data reassured the population concentrations. The results will be useful in urban planning and growth management.

• Journal of Korean Society of Transportation
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• v.35 no.6
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• pp.525-544
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• 2017

With the advent of the big data era, the interest in the development of land using traffic data has increased significantly. However, the current research on traffic big data lingers around organizing or calibrating the data only. In this research, a novel method for discovering the hidden values within the traffic data through data mining is proposed. Considering the fact that traffic data and network structures have similarities, network analysis algorithms are used to find valuable information in the actual traffic volume data. The PageRank and HITS algorithms are then employed to find the centralities. While conventional methods present centralities based on uncomplicated traffic volume data, the proposed method provides more reasonable centrality locations through network analysis. Since the centrality locations that we have found carry detailed spatiotemporal characteristics, such information can be used as an objective basis for making policy decisions.

• Journal of Korea Port Economic Association
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• v.28 no.1
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• pp.105-122
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• 2012

This paper proposes a fuzzy-based AHP model by which the greenhouse gas reduction for container terminal problem was systematically structured and then evaluated. The model was established by exploiting a fuzzy theory and AHP for capturing the inexactness and vagueness of information. In this study, measurement areas were selected for equipment aspect, operating aspect, and energy aspect. The greenhouse gas reduction is the number one priority in the equipment aspect, operating aspect, energy aspect in order. The analysis result of equipment aspect reveals that the most important element is electrical T/C. The most important element of operating and energy aspect were a container rehandling and a LED lighting. As for the whole priority which conversion weight was applied, the results were shown as follows: an electrical T/C(16.2%) as the first rank: a hybrid Y/T(14.4%) as the second rank: a AMP(10.6%) as the third rank. The result of this study suggests some guidelines for deciding priority of greenhouse gas reduction for container terminal.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.4
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• pp.65-73
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• 2007

This study devotes to compare the accuracy of Top-N recommendations of items transacted on the web site for customers with the accuracy of rank conformity of the real ratings with estimated ratings for customers preference about items generated from two types of collaborative filtering algorithms. One is Neighborhood Based Collaborative Filtering Algorithm(NBCFA) and the other is Correspondence Mean Algorithm(CMA). The result of this study shows the accuracy of Top-N recommendations and the rank conformity of real ratings with estimated ratings generated by CMA are better than that of NBCFA. It would be expected that the customer's satisfaction in Recommender System is more improved by using the prediction result from CMA than NBCFA, and then Using CMA in collaborative filtering recommender system is more efficient than using NBCFA.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.1
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• pp.137-142
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• 2019

There are two methods for evaluating two or more mutually exclusive projects. One is a total investment approach and the other is an incremental investment approach. The former can rank projects by the criterion of the net present value, but the latter can't do it. An incremental investment approach is only possible when all pairwise alternatives are compared. Thus an incremental investment approach is superior in ranking them over an incremental investment approach. To do so, a principle of comparison must be established. Comparisons of profitability are reasonable when operating the same amount of investment over the same period of time. One principle is that all projects are invested in the largest of the projects. Another principle is that all projects are invested during the longest project life of the projects. In this paper, even if the principle is followed, it will be shown that the external rate of return fails to rank them. However, the productive rate of return criterion would prove to be able to rank them like the net present value standard, provided that the principle of comparison is kept. In addition, rate of returns can be assessed so that all mutually exclusive projects can be compared at once, such as on the criterion of the net present value. That is, it can be also compared with many other returns, such as the profit rates on financial investments or real investments.

• Journal of the Korea Convergence Society
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• v.10 no.8
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• pp.255-264
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• 2019

This study focuses on the recent turnover of film crews in Korean film industry. Determinants that could have a significant impact on the turnover of film crews are identified through empirical research, in order to seek measures to prevent the loss of experienced film crews. In order for respondents to verify research questions regarding turnover of the film crews, ordered logistic and marginal effects analysis using SPSS and STATA are conducted with the data obtained by surveying 402 film crews in various areas. Data analysis revealed that the variables that have a significant effect on the turnover of film crews are artists' identity, job rank, career barrier and job satisfaction. The characteristics of risk groups with high turnover can be concluded that they are low in job rank and have many career problems, poor job satisfaction and strong identity as a labourer rather than artist's identity. Based on the main findings, practical implications are discussed.

• Asia Marketing Journal
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• v.15 no.1
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• pp.43-55
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• 2013

Since movies are experience goods, consumers are easily influenced by other consumers' behavior. For moviegoers, box office rank is the most credible and easily accessible information. Many studies have found that the relationship between a movie's box office rank and its revenue departs from the Pareto distribution, and this phenomenon has been named "increasing returns to information." The primary objective of the current research is to apply the empirical model proposed by De Vany and Walls (1996) to the Korean movie market in order to examine whether the same phenomenon prevails in the Korean movie market. The other purpose of the present study is to provide managers with useful implications about the release timing of a movie by finding different curvatures that depend upon seasonality. The empirical test on the Korean movie market shows similar results as prior studies conducted on the U.S., Hong Kong, and U.K. movie markets. The phenomenon of increasing returns is generated by information transmission among consumers, which makes some movies become blockbusters and others bombs. The proposed model can also be interpreted in such a way that a change in the rank has a nonlinear effect on the movie's performance. If a movie climbs up the chart, it would be rewarded more than its proportion. On the other hand, if a movie falls down in the ranks, its performance would drop rapidly. The research result also indicates that the phenomenon of increasing returns occurs differently depending on when the movies are released. Since the tendency of the increasing returns to information is stronger during the peak seasons, movie marketers should decide upon the release timing of a movie based on its competitiveness. If a movie has substantial potential to incur positive word-of-mouth, it would be more reasonable to release the movie during the peak season to enjoy increasing returns. Otherwise, a movie should be released during the low season to minimize the risk of being dropped from the chart.