• Asia pacific journal of information systems
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• v.17 no.4
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• pp.187-206
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• 2007

The development of computer and information technology has been combined with the information superhighway internet infrastructure, so information widely spreads not only in special fields but also in the daily lives of people. Information ubiquity influences the traditional way of transaction, and leads a new E-commerce which distinguishes from the existing E-commerce. Not only goods as physical but also service as non-physical come into E-commerce. As the scale of E-Commerce is being enlarged as well. It keeps people from finding information they want. Recommender systems are now becoming the main tools for E-Commerce to mitigate the information overload. Recommender systems can be defined as systems for suggesting some Items(goods or service) considering customers' interests or tastes. They are being used by E-commerce web sites to suggest products to their customers who want to find something for them and to provide them with information to help them decide which to purchase. There are several approaches of recommending goods to customer in recommender system but in this study, the main subject is focused on collaborative filtering technique. This study presents a possibility of pre-evaluation for the prediction performance of customer's preference in collaborative filtering before the process of customer's preference prediction. Pre-evaluation for the prediction performance of each customer having low performance is classified by using the statistical features of ratings rated by each customer is conducted before the prediction process. In this study, MovieLens 100K dataset is used to analyze the accuracy of classification. The classification criteria are set by using the training sets divided 80% from the 100K dataset. In the process of classification, the customers are divided into two groups, classified group and non classified group. To compare the prediction performance of classified group and non classified group, the prediction process runs the 20% test set through the Neighborhood Based Collaborative Filtering Algorithm and Correspondence Mean Algorithm. The prediction errors from those prediction algorithm are allocated to each customer and compared with each user's error. Research hypothesis : Two research hypotheses are formulated in this study to test the accuracy of the classification criterion as follows. Hypothesis 1: The estimation accuracy of groups classified according to the standard deviation of each user's ratings has significant difference. To test the Hypothesis 1, the standard deviation is calculated for each user in training set which is divided 80% from MovieLens 100K dataset. Four groups are classified according to the quartile of the each user's standard deviations. It is compared to test the estimation errors of each group which results from test set are significantly different. Hypothesis 2: The estimation accuracy of groups that are classified according to the distribution of each user's ratings have significant differences. To test the Hypothesis 2, the distributions of each user's ratings are compared with the distribution of ratings of all customers in training set which is divided 80% from MovieLens 100K dataset. It assumes that the customers whose ratings' distribution are different from that of all customers would have low performance, so six types of different distributions are set to be compared. The test groups are classified into fit group or non-fit group according to the each type of different distribution assumed. The degrees in accordance with each type of distribution and each customer's distributions are tested by the test of ${\chi}^2$ goodness-of-fit and classified two groups for testing the difference of the mean of errors. Also, the degree of goodness-of-fit with the distribution of each user's ratings and the average distribution of the ratings in the training set are closely related to the prediction errors from those prediction algorithms. Through this study, the customers who have lower performance of prediction than the rest in the system are classified by those two criteria, which are set by statistical features of customers ratings in the training set, before the prediction process.

• Korean Journal of Remote Sensing
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• v.35 no.6_3
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• pp.1221-1233
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• 2019

Estimating damage in each sector that can be caused by volcanic ash deposition, is very important to prepare the volcanic ash disaster. In this study, we showed predicted-Korean-volcanic-ash damage of each sector by using volcanic ash diffusion simulation and spatial-data-based volcanic ash damage sector in previous study. To this end, volcanic ash related base maps were generated by collecting and processing spatial information data. Finally, we showed Korean-volcanic-ash-deposition damages by sector using the collected Mt. Aso volcanic ash scenarios via overlapping analysis. As a result, volcanic-ash-related damages were expected to occur in the 162 and 134 districts for each Aso volcanic ash scenarios, since those districts exceeds the minimum volcanic ash damage criterion of 0.01 mm. Finally, we compared possible volcanic ash damages by sectors using collected and processed spatial data, after selecting administrative districts(Scenario 190805- Kangwon-do, Kyungsangbuk-do; Scenario 190811-Chuncheon-si, Hongcheon-si) with the largest amount of volcanic ash deposition.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.12
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• pp.1189-1193
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• 2010

Mobility management is one of the most important research issues in 6LoWPAN, Since the IP-WSN application domain is expanded to real-time applications such as healthcare and surveillance systems, a fast and seamless handover becomes an important criterion in 6LoWPAN. However, a draft of IETF 6LoWPAN WG for mobility support does not decrease handover delay. Although LoWMob supports a fast intra-PAN handover. it can be supported when the infrastructure node has the location information of the other nodes in the mobile node's moving direction. In this paper, we propose a fast and seamless mobility protocol to support intra-PAN handover, named intra-MARIO. In intra-MARIO, a parent node of the mobile node preconfigures its handover to the PAN when the parent node detects its movement, thereby reducing the handover delay. Since intra-MARIO also supports route optimization, the mobile node can communicate with its corresponding nodes through the optimal route. In this paper, we analysis the signaling cost and evaluates that the handover can be completed in 20ms by simulation.

• The KIPS Transactions:PartB
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• v.11B no.6
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• pp.653-660
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• 2004

Object-oriented analysis-synthesis coding (OOASC) subdivides each image of a sequence into a number of moving objects and estimates and compensates the motion of each object. It employs a motion parameter technique for estimating motion information of each object. The motion parameter technique employing gradient operators requires a high computational load. The main objective of this paper is to present efficient motion parameter estimation techniques using the hierarchical structure in object-oriented analysis-synthesis coding. In order to achieve this goal, this paper proposes two algorithms : hybrid motion parameter estimation method (HMPEM) and adaptive motion parameter estimation method (AMPEM) using the hierarchical structure. HMPEM uses the proposed hierarchical structure, in which six or eight motion parameters are estimated by a parameter verification process in a low-resolution image, whose size is equal to one fourth of that of an original image. AMPEM uses the same hierarchical structure with the motion detection criterion that measures the amount of motion based on the temporal co-occurrence matrices for adaptive estimation of the motion parameters. This method is fast and easily implemented using parallel processing techniques. Theoretical analysis and computer simulation show that the peak signal to noise ratio (PSNR) of the image reconstructed by the proposed method lies between those of images reconstructed by the conventional 6- and 8-parameter estimation methods with a greatly reduced computational load by a factor of about four.

• Journal of Korean Library and Information Science Society
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• v.19
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• pp.145-209
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• 1992

This study, that is made by an on-the-spot survey and a library survey, is aimed at finding some problems in the recognition regarding public library users and suggesting the clue to solve the problems revealed in the way of having compared with 'Book-Room' and Public Library. Poor material was always a troublemaker in this study. Especially the part of 'Book-Room' phenomenon is wholly dependent upon a field survey, that is, interview with a 'book-room' clerks, gathering the advertising leaflets, a close observation on 'Book-Room', etc. There are little printed materials, much less precedent research theses. In the other parts of this paper, there are needed good statistical materials, but the nortion presented in the public library user statistics-for example pupil, students, housewives, old men, the generality of people, etc.- is so vague that it is insufficient and unhelpful for this study. In my judgment, with all these limitations, this article gets some results as follows : 1. 'Book-Room' is the cultural organization which is being operated by, for, of the community inhabitants and it takes on the character of movement - labor movement, cultural movement, and community movement. 2. The pioneer of the Book-Room is 'Yangso Hyupdong chohap' (which means good book- cooperative association) lasted from 1978 to the next year. 3. 'Arom'(means learning) Book-Room is the first real Book-Room at Seomyon district in Pusan established in 1987. 4. Book-Room can be classified by its character as 'Labor BookRoom' and 'Cultural Book-Room'. There are 10 Labor BookRooms and 4 Cultural Book-Rooms in Pusan. 5. Labor Book-Rooms organized themselves to 'Labor Book-Room conference'. 6. Book-Rooms have done their best to extort the needs and interests of the community inhabitants, but relatively public libraries do not, hence the majority of residents are neglected from the public library service. This is at Book-Rooms' back to have been spread so quickly. 7. There is a very large gap between the component ratio of community inhabitants by class and that of public library users by same criterion, that is, in the case of the former, the labor class goes beyond a half point, in the latter, the majority of public library user is composed of students and housewives. 8. Researchers and librarians have concentrated their attention and effort not upon whole residents in community but upon existing users at present time. They do not try to develope potential users. So, researchers' and librarians' recognition regarding the public library users needs to be changed. 9. The concept of 'core-user' may be the key to solve the problems related with public library users. For the purpose of ensuring the 'core-user', it is necessary to study the community and inhabitants.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.258-266
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• 2013

We propose adaptive detection algorithm to reduce a false alarm by considering the characteristics of the random noise on the detection system based on a seismic sensor. The proposed algorithm consists of the first step detection using kernel function and the second step detection using detection classes. Kernel function of the first step detection is obtained from the threshold of the Neyman-Pearon decision criterion using the probability density functions varied along the noise from the measured signal. The second step detector consists of 4 step detection class by calculating the occupancy time of the footstep using the first detected samples. In order to verify performance of the proposed algorithm, the detection of the footsteps using measured signal of targets (walking and running) are performed experimentally. The detection results are compared with a fixed threshold detector. The first step detection result has the high detection performance of 95% up to 10m area. Also, the false alarm probability is decreased from 40% to 20% when it is compared with the fixed threshold detector. By applying the detection class(second step detector), it is greatly reduced to less than 4%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9B
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• pp.1742-1754
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• 1999

In this paper, we propose a rate control scheme, using histogram based rate-distortion (R-D) estimation, which produces a consistent picture quality between consecutive frames. The histogram based R-D estimation used in our rate control scheme offers a closed-form mathematical model that enable us to predict the bits and the distortion generated from an encoded frame at a given quantization parameter (QP) and vice versa. The most attractive feature of the R-D estimation is low complexity of computing the R-D data because its major operation is just to obtain a histogram or weighted histogram of DCT coefficients from an input picture. Furthermore, it is accurate enough to be applied to the practical video coding. Therefore, the proposed rate control scheme using this R-D estimation model is appropriate for the applications requiring low delay and low complexity, and controls the output bit-rate ad quality accurately. Our rate control scheme ensures that the video buffer do not underflow and overflow by satisfying the buffer constraint and, additionally, prevents quality difference between consecutive frames from exceeding certain level by adopting the distortion constraint. In addition, a consistent considering the maximum tolerance BER of the voice service. Also in Rician fading channel of K=6 and K=10, considering CLP=$10^{-3}$ as a criterion, it is observed that the performance improment of about 3.5 dB and 1.5 dB is obtained, respectively, in terms of $E_b$/$N_o$ by employing the concatenated FEC code with pilot symbols.

• International Commerce and Information Review
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• v.16 no.3
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• pp.53-71
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• 2014

This study analysis the current status and policies of Korean Medium Sized Enterprises, and compared with those of U.S and Germany Recently the number of Korean Medium Sized Enterprises is highly increased. But the average sales, employment, and export which can be the indicator for growth were decreased, particularly the decrease of R&D intensity was remarkable. There are 3 policies suggestions necessary to accelerate growth of Medium Sized Enterprises. First, reform the system for Medium Sized Enterprises to grow their activity. There need to direct support as well as arrange governmental regulation. Second, need to increase R&D aid for enhance innovative competence of MSE. Lone-term continuous support for R&D is most import for promoting competitive Medium Sized Enterprises. And the lastly, for successful supporting policy there need to modify the comprehensive criterion for present Medium Sized Enterprises.

• International Commerce and Information Review
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• v.19 no.2
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• pp.145-166
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• 2017

The FTA conventional tariffs shall be applied that the imported goods are subject to the conventional tariffs under any agreement, and the origin of the good is the contracting state in accordance with the criteria for determination origin under any agreement. An importer who intends to be eligible for the application of a conventional tariff shall file a request for the application of a conventional tariff with the head of the competent customs house before the relevant import declaration is accepted. The purpose of this study is to examine the legal standard and verification cases for the judgement of the tax tribunal of FTA conventional tariffs. Through this study, this paper is to provide several implications for companies seeking the benefits of FTA conventional tariffs. The Korean companies to do the following: confirm the effective requirements for direct transport of goods through non-parties under the Korea EU FTA, confirm the criterion for application of conventional tariffs such as certificate of origin and claims for ex post facto conventional tariffs under the Korea US FTA, confirm the issuer of origin declaration and the recognition of origin declaration of bill of lading under the Korea EU FTA, utilize the tax appeal system by denial of FTA conventional tariffs, and prepare the discrepancies in interpretation of legal standard under FTA and FTA Special Customs Act.

• Journal of the Korean Data and Information Science Society
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• v.27 no.3
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• pp.587-598
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• 2016

In predicting an outcome of election using a variety of methods ahead of the election, non-response is one of the major issues. Therefore, to address the non-response issue, a variety of methods of non-response imputation may be employed, but the result of forecasting tend to vary according to methods. In this study, in order to improve electoral forecasts, we studied a model based method of non-response imputation attempting to apply the Monte Carlo Expectation Maximization (MCEM) algorithm, introduced by Wei and Tanner (1990). The MCEM algorithm using maximum likelihood estimates (MLEs) is applied to solve the boundary solution problem under the non-ignorable non-response mechanism. We performed the simulation studies to compare estimation performance among MCEM, maximum likelihood estimation, and Bayesian estimation method. The results of simulation studies showed that MCEM method can be a reasonable candidate for non-response model estimation. We also applied MCEM method to the Korean presidential election exit poll data of 2012 and investigated prediction performance using modified within precinct error (MWPE) criterion (Bautista et al., 2007).