• Journal of the Korea Society of Computer and Information
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• v.17 no.12
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• pp.149-158
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• 2012

Proposed is a hybrid randomizing function using two asymptotically optimal randomizing functions: Elias function and Peres function. Randomizing function is an mathematical abstraction of producing a uniform random bits from a source of randomness with bias. It is known that the output rate of Elias function and Peres function approaches to the information-theoretic upper bound. Especially, for each fixed input length, Elias function is optimal. However, its computation is relatively complicated and depends on input lengths. On the contrary, Peres function is defined by a simple recursion. So its computation is much simpler, uniform over the input lengths, and runs on a small footprint. In view of this tradeoff between computational complexity and output efficiency, we propose a hybrid randomizing function that has strengths of the two randomizing functions and analyze it.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.2
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• pp.159-167
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• 2009

To obtain the gravity data with consistent quality and good distribution over Korea, to overcome the difficulties in constructing precision geoid from biased distribution of ground data, to resolve the discrepancy between the ground and ocean gravity data, an airborne gravity survey was conducted from Dec. 2008 to Jan. 2009. The data was measured at the average flying height of 3,000m and the data with cross-over error of 2.21mGal is obtained. The geoid constructed using this airborne gravity data shows the range of 9.34 $\sim$ 33.88m. Comparing the geoid with respect to the GPS/levelling data, a precision of 0.145m is obtained. After fitting, the degree of fit to GPS/levelling data was calculated about 5cm. It was found that there exists large biases in the area of south-western and northern part of the peninsular which is considered to be the effect of distorted vertical datum in Korea. Thus, more investigation on vertical datum would be needed in near future.

• Journal of the Korean Society for Library and Information Science
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• v.49 no.4
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• pp.221-239
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• 2015

The purpose of this study is to review the current status of disseminating knowledge on Korean people by analyzing biographies for juvenile and general audiences with the subject term 'Korea' in WorldCat. Languages and topics of 15,007 bibliographic records and topic facets, biographees, and holding libraries in the U.S. of 487 biographies for juvenile audiences were analyzed. Major findings are as follows: 1) 30 English biographies are held by may libraries in the U.S. and the most popular subjects are Kim Il-song and Kim Jong-il, 2) 457 Korean biographies are not held by many libraries, and King Sejong and the General Yi Sun-sin are the most popular subjects, 3) many Korean biographies are picture books for the very young readers with the focus on Korean folklores and anecdotal biographies, and 4) there are some errors in topic facets, dispersion of biographees, and inaccurate holding lists of bibliographic records. Therefore, there seems to be little to read with an interest and promote the diffusion of knowledge on Korean people through libraries.

• Human Ecology Research
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• v.57 no.4
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• pp.459-472
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• 2019

The purpose of this study was to develop an Implicit Association Test to measure students' gender-biased attitude toward Home Economics, a required subject in middle-school and to examine the effects of gender, gender-biased attitude toward Home Economics, and gender egalitarianism on the perception of the subject. A total of 508 male and female middle-school students were surveyed using Qualtrics. The results revealed that the students had a gender-biased attitude of perceiving Home Economics as feminine as a whole, and this tendency was more evident among female than male students. To the contrary, their attitudes toward Home Economics as a subject was generally favorable when asked explicitly using self-administered questions. Among the high school elective classes, students preferred 'fashion' most, followed by 'dietary life', 'technology and home economics', and 'family life culture'. Female students, students with patriarchal attitude, and students who has gender-biased attitude toward Home Economics were more likely to perceive Home Economics as an alienated and less important subject. The generally positive explicit attitude toward Home Economics may be the results the social desirability effect due to the education. However, the home economists should develop a plan to overcome the gender-biased implicit attitude in order for the value of Home Economics as a subject to be fully addressed.

• Journal of Korea Port Economic Association
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• v.22 no.3
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• pp.161-188
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• 2006

The purpose of this study is to analyze traffic volume between the Korean container ports located at the west coast and northern Chinese ports and then the distribution trend of container between Korea and China. The findings of the study are as follows. First, Container traffic between western Korean ports and northern Chinese ports has been increasing due to an increasing trade volume between both countries and geographical accessibility. Second, Seoul and neighboring area tend to use the trade route between the western ports and northern Chinese because of lower logistics costs and time-saved advantage compared to another ports. Third, the growth of the western ports did depend mainly on the northern China oriented growth. Such a fact could leads to the overlapping investment in port development in Korea and another intense competition among national ports to attract cargoes and liners. Therefore, port development policy considering the characteristics and function of national ports have to be established. and also alternatives and strategies for improving the competitive edge of small and medium sized shipping lines against the opening of shipping market have to be worked out.

• The Mathematical Education
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• v.60 no.1
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• pp.61-76
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• 2021

The purpose of this study is to analyze the errors and difficulties which pre-service secondary teachers shows during the task modification in consideration of the cognitive demand and to provide significant implications to the pre-service teacher education program related to the modification of the mathematical tasks. In the pursuit of this purpose, tasks were selected from perpendicular bisector units and 24 pre-service teachers were asked to modify the tasks to higher and lower level tasks. After the modification activities, opportunities for reflection and modification were provided. The findings from analysis are as follows. Pre-service teachers had a difficulty to distinguish between PNC tasks and PWC tasks. Also, We identified the interference phenomena that pre-service teachers depended on the apparent elements of the task. Pre-service teachers showed a tendency to overlook the learning objectives and learning hierarchy during the task modification, and to focus on some types of task modification. However, pre-service teachers were able to have meaningful learning opportunities and extend the category of tools to technology including Geogebra through self-reflection and correction activities on task modification. The above results were summed up and we presented the implications to the task modification program in the pre-service secondary teacher education.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.3
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• pp.79-84
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• 2021

A feature extraction method capable of reflecting features well while mainaining the properties of data is required in order to process high-dimensional data. The principal component analysis method that converts high-level data into low-dimensional data and express high-dimensional data with fewer variables than the original data is a representative method for feature extraction of data. In this study, we propose a principal component analysis method based on adaptive correlation when selecting principal component variables in principal component analysis for data feature extraction when the data is high-dimensional. The proposed method analyzes the principal components of the data by adaptively reflecting the correlation based on the correlation between the input data. I want to exclude them from the candidate list. It is intended to analyze the principal component hierarchy by the eigen-vector coefficient value, to prevent the selection of the principal component with a low hierarchy, and to minimize the occurrence of data duplication inducing data bias through correlation analysis. Through this, we propose a method of selecting a well-presented principal component variable that represents the characteristics of actual data by reducing the influence of data bias when selecting the principal component variable.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.2
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• pp.17-32
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• 2022

This study explored an approach to estimate a flow-density diagram(FD) on a link in highway traffic environment by utilizing probe vehicles' time headway records. To study empirical flow-density diagram(EFD), the probe vehicles with vision sensors were recruited for collecting driving records for nine months and the vision sensor data pre-processing and GIS-based map matching were implemented. Then, we examined the new EFDs to evaluate validity with reference diagrams which is derived from loop detection traffic data. The probability distributions of time headway and distance headway as well as standard deviation of flow and density were utilized in examination. As a result, it turned out that the main factors for estimation errors are the limited number of probe vehicles and bias of flow status. We finally suggest a method to improve the accuracy of EFD model.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.1
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• pp.25-38
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• 2022

With the diversification of payment methods and games, related financial accidents are causing serious problems for users and game companies. Recently, game companies have introduced an Fraud Detection System (FDS) for game payment systems to prevent financial incident. However, FDS is ineffective and cannot provide major evidence based on judgment results, as it requires constant change of detection patterns. In this paper, we analyze abnormal transactions among payment log data of real game companies to generate related features. One of the unsupervised learning models, Autoencoder, was used to build a model to detect abnormal transactions, which resulted in over 85% accuracy. Using X-FDS (Explainable FDS) with XAI-SHAP, we could understand that the variables with the highest explanation for anomaly detection were the amount of transaction, transaction medium, and the age of users. Based on X-FDS, we derive an improved detection model with an accuracy of 94% was finally derived by fine-tuning the importance of features that adversely affect the proposed model.

• The Journal of the Korea Contents Association
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• v.21 no.11
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• pp.586-597
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• 2021

The purpose of the study is to investigate how females in the 2nd vaccination group(that is, women between the ages of 14-26) perceive cervical cancer, HPV vaccine, and the current campaign on HPV vaccine. In-depth interviews with 19 female college students between the ages of 20-26 revealed that the participants perceive the cervical cancer and vaccine as unimportant due to limited information; they were exposed to related information at random and there were lack of important information; and information provided were viewed as gender-biased. Moreover, social taboo-ness, cost and fear of its side-effects were found to influence women from getting vaccinated. Results show that participants want more fact-based and practical information, information that includes peers and men, as well as a campaign that has more frequent contact and accessibility. Findings of the study can be used for HPV prevention education in the future targeting women between the ages of 13-35. The study provides suggestion for future research and changes needed in HPV vaccine campaigns.