• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.4
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• pp.14-34
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• 2023

The purpose of this study was to calculate the appropriate yellow-signal time for intersections, to find out the relationship between the approach speed and intersection width when calculating the time, and to secure safety by minimizing conflicts and dilemma sections in intersections that change according to the signal operation. For this purpose, 6,824 data points from 5 intersections were collected and analyzed. The main results of the study are as follows. First, the approach speed of individual vehicles in different lanes was analyzed, and the width of an intersection was defined by considering the conflict in each direction. Second, we developed a multiple regression model based on the approach speed and conflict points, which compensated for the problems of an existing formula. Third, a standard table is presented for applying the appropriate yellow-signal time according to the approach speed and intersection width based on a development formula. A method is also presented to determine the safety of the length of the dilemma according to the change in the yellow-light time by presenting a calculation table that can cross-analyze the yellow-signal time and a dilemma section using the relationship.

• Knowledge Management Research
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• v.22 no.2
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• pp.1-17
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• 2021

In this study, we predicted the bitcoin prices of Bithum and Coinbase, a leading exchange in Korea and USA, using ARIMA and Recurrent Neural Networks(RNNs). And we used news articles from each country to suggest a separated RNN model. The suggested model identifies the datasets based on the changing trend of prices in the training data, and then applies time series prediction technique(RNNs) to create multiple models. Then we used daily news data to create a term-based dictionary for each trend change point. We explored trend change points in the test data using the daily news keyword data of testset and term-based dictionary, and apply a matching model to produce prediction results. With this approach we obtained higher accuracy than the model which predicted price by applying just time series prediction technique. This study presents that the limitations of the time series prediction techniques could be overcome by exploring trend change points using news data and various time series prediction techniques with text mining techniques could be applied to improve the performance of the model in the further research.

• Journal of Korean society of Dental Hygiene
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• v.14 no.3
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• pp.381-390
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• 2014

Objectives : The purpose of the study is to investigate the relationship between job-stress and temporomandibular joint(TMJ) disorder in dental hygienists. This study will provide the basic data to improve the working condition and the quality of life. Methods : The subjects were 229 dental hygienists at general hospitals in Seoul, Korea. A self-reported questionnaire was filled out from May 20 to June 20, 2013. The questionnaire consisted of 4 questions of demographic features, 11 questions for TMJ symptoms and 5 questions for job stress. The data were analyzed by frequency analysis, chi-square test, Mann-Whitney U test and multiple job-stress logistic regression analysis using SPSS version 21.0. Results : During the last six months, 53.3%(122 persons) of the dental hygienists had TMJ disorder symptoms including joint noise(40.6%, 93 persons), TMJ pain(31.4%, 71 persons) and limitation of TMJ(21.8%, 50 persons). Job-stress is divided into two ranges including high stress group(4.3-5.0 points) and low stress group(0.0-3.6 points) in TMJ pain and joint noise(p<0.05). TMJ pain was closely related to low back pain, pelvis pain and tension headache arising from the uncomfortable working posture. Conclusions : It is necessary to prevent the job stress in the dental hygienists by the improvement of working condition, emotional stability, and frequent postural change.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.185-185
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• 2011

Mapping of artificial levee lines, one of major tasks in river zone mapping, is critical to prevention of river flood, protection of environments and eco systems in river zones. Thus, mapping of artificial levee lines is essential for management and development of river zones. Coastal mapping including river zone mapping has been historically carried out using surveying technologies. Photogrammetry, one of the surveying technologies, is recently used technology for national river zone mapping in Korea. Airborne laser scanning has been used in most advanced countries for coastal mapping due to its ability to penetrate shallow water and its high vertical accuracy. Due to these advantages, use of LiDAR data in coastal mapping is efficient for monitoring and predicting significant topographic change in river zones. This paper introduces a method for construction of a 3D artificial levee line using a set of LiDAR points that uses normal vectors. Multiple steps are involved in this method. First, a 2.5-dimensional Delaunay triangle mesh is generated based on three nearest-neighbor points in the LiDAR data. Second, a median filtering is applied to minimize noise. Third, edge selection algorithms are applied to extract break edges from a Delaunay triangle mesh using two normal vectors. In this research, two methods for edge selection algorithms using hypothesis testing are used to extract break edges. Fourth, intersection edges which are extracted using both methods at the same range are selected as the intersection edge group. Fifth, among intersection edge group, some linear feature edges which are not suitable to compose a levee line are removed as much as possible considering vertical distance, slope and connectivity of an edge. Sixth, with all line segments which are suitable to constitute a levee line, one river levee line segment is connected to another river levee line segment with the end points of both river levee line segments located nearest horizontally and vertically to each other. After linkage of all the river levee line segments, the initial river levee line is generated. Since the initial river levee line consists of the LiDAR points, the pattern of the initial river levee line is being zigzag along the river levee. Thus, for the last step, a algorithm for smoothing the initial river levee line is applied to fit the initial river levee line into the reference line, and the final 3D river levee line is constructed. After the algorithm is completed, the proposed algorithm is applied to construct the 3D river levee line in Zng-San levee nearby Ham-Ahn Bo in Nak-Dong river. Statistical results show that the constructed river levee line generated using a proposed method has high accuracy in comparison to the ground truth. This paper shows that use of LiDAR data for construction of the 3D river levee line for river zone mapping is useful and efficient; and, as a result, it can be replaced with ground surveying method for construction of the 3D river levee line.

• Journal of The Korean Digital Architecture Interior Association
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• v.13 no.3
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• pp.15-23
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• 2013

As a succeeding analysis on the variables' significance to 'Quality of Life(QOL)'(Kim, Dong-Yoon, 2012a), which has a purpose of trying to enhance the intersubjectiveness by means of quantitive methods to find the factors on the QOL, this study aims at finding the time serial change in the deciding factors to deepen the related researches on the theme. Using the similar statistical methods such as multiple regression and factor analysis for "2012 Seoul Survey" this study shows two similar points and one differentia. The similarities include the fact that five subcategories of happiness have relative statistical importance in the order of (1)financial condition, (2)health condition, (3)social activities, (4)community relationship and (5)family life and the fact that the five subcategories are conceptually different from the 5 deciding factors, which means the possibility to improve the survey design. And the difference is the 5 factors such as (1) social trust - amenities, (2)cultural life, (3)social indiscrimination - hope for elevation, (4)sharing - giving and (5)community spirit which are largely different from preceding study. Although only the first two factors have statistical significance this result has a implication that they reflect the new paradigm of social capital and the essential necessity of human survival; sharing-community-culture.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.55-58
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• 2008

Designers, who design industry products, use CAD(Computer Aided Design) tools for making new design and looking around virtual 3D models. Hand-drawings and sketches show only one viewpoint limiting 3D perception. However, CAD system that provides automation and multiple view points, can help to save time and cost. Accordingly, we developed Augmented Reality(AR) and Rapid Prototyping(RP) based product design system that is interactive and realistic This AR based design system utilize mockups that are made of urethane and styrofoam where as users change 3D model's color, texture and user interface. These interactive ways help to evaluate design more instinctively.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.3
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• pp.266-273
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• 2013

With the worldwide trend of controlling the utilization of fossil fuels inducing global climate change, many efforts will have to be made on securing a sustainable energy supply. Tidal current is a concentrated form of gravitational energy, its resource is significant, but limited locations. To effectively capture tidal current energy from the sea, a group of tidal turbines should be formed and positioned with optimal size and spacing for absorbing from multiple points. Thus, the flow field including turbines becomes a huge domain, a so-called tidal farm. It can be very convenient technically and economically if a whole turbine farm is simulated by means of actuator disc thoery. So, the analysis method using actuator discs coupled with a solution of Reynolds Averaged Navier-Stokes (RANS) equations is adopted for actual tidal turbines. Actuator discs have regions where similar forces imposed by actual turbines are applied to a flow. As working in group formation, turbines naturally have interaction effects on one another. Therefore, the present paper investigate the evaluation on the operating performance of tidal farm in terms of the mutual influence among turbine units with various lateral and longitudinal spacing. Authors expect that results of the present study contribute to the development of tidal farm for the future potential energy.

• Journal of Korean Public Health Nursing
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• v.35 no.1
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• pp.120-134
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• 2021

Purpose: The reproductive health of women in early adulthood can affect pregnancy, childbirth, and menopause in later life. Menstrual symptoms not only affect daily life, but are also a reflection of a woman's reproductive health. This study was conducted to explore the factors affecting menstrual symptoms among university students. Methods: The general characteristics, life style, menstrual characteristics, stress, and menstrual symptom of 177 female students were assessed through an online survey at one university. An independent sample t-test, one-way variance analysis, correlation analysis, and multiple regression analysis were performed using the SPSS 22.0 program. Results: The menstrual symptom score was 91.68±32.11 points, and the score of 'mood change' was the highest. Stress (��=.38, p<.001), amount of menstruation (��=.20, p=.001), menarche age (��=-.18, p=.003), health problems (��=.16, p=.010), and age (��=.15, p=.016) were found to have a significant effect on menstrual symptom, and the explanatory power of the regression model was 40%. Conclusion: This study investigated the degree and influencing factors of menstrual symptom using the Korean Menstrual Symptom Scale (KMSS) developed for Korean university students. Among the factors influencing menstrual symptom, stress appeared to play a significant role. Stress management, observation of menstrual characteristics, and general health care are necessary to maintain a woman's reproductive health.

• Journal of Distribution Science
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• v.21 no.9
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• pp.103-114
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• 2023

Purpose: This paper aims to assess psychological heuristics' effectiveness on cumulative returns after significant stock price changes. Specifically, it compares availability and anchoring heuristics' empirical validity due to conflicting stock return predictions. Research Design, Data, and Methodology: This paper analyzes stock price changes of Korean distribution industry stocks in the KOSPI market from January 2004 to July 2022, where daily fluctuations exceed 10%. It evaluates availability heuristics using daily KOSPI index changes and tests anchoring heuristics using 52-week high and low stock prices as reference points. Results: As a result of the empirical analysis, stock price reversals did not consistently appear alongside changes in the daily KOSPI index. By contrast, stock price drifts consistently appeared around the 52-week highest stock price and 52-week lowest stock price. The result of the multiple regression analysis which controlled for both company-specific and event-specific variables supported the anchoring heuristics. Conclusions: For stocks related to the Korean distribution industry in the KOSPI market, the anchoring heuristics theory provides a consistent explanation for stock returns after large-scale stock price fluctuations that initially appear to be random movements.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.6
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• pp.625-635
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• 2014

Multiple strips are required for large area mapping using ALS (Airborne Laser Scanner) system. LiDAR (Light Detection And Ranging) data collected from the ALS system has discrepancies between strips due to systematic errors of on-board laser scanner and GPS/INS, inaccurate processing of the system calibration as well as boresight misalignments. Such discrepancies deteriorate the overall geometric quality of the end products such as DEM (Digital Elevation Model), building models, and digital maps. Therefore, strip adjustment for minimizing discrepancies between overlapping strips is one of the most essential tasks to create seamless point cloud data. This study implemented area-based matching (ABM) to determine conjugate features for computing 3D transformation parameters. ABM is a well-known method and easily implemented for this purpose. It is obvious that the exact same LiDAR points do not exist in the overlapping strips. Therefore, the term "conjugate point" means that the location of occurring maximum similarity within the overlapping strips. Coordinates of the conjugate locations were determined with sub-pixel accuracy. The major drawbacks of the ABM are sensitive to scale change and rotation. However, there is almost no scale change and the rotation angles are quite small between adjacent strips to apply AMB. Experimental results from this study using both simulated and real datasets demonstrate validity of the proposed scheme.