• Journal of the Korean earth science society
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• v.36 no.5
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• pp.437-446
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• 2015

Many edge detection methods, based on horizontal and vertical derivatives, have been introduced to provide us with intuitive information about the horizontal distribution of a subsurface anomalous body. Understanding the characteristics of each edge detection method is important for selecting an optimized method. In order to compare the characteristics of the individual methods, this study applied each method to synthetic magnetic data created using homogeneous prisms with different sizes, the numbers of bodies, and spacings between them. Seven edge detection methods were comprehensively and quantitatively analyzed: the total horizontal derivative (HD), the vertical derivative (VD), the 3D analytic signal (AS), the title derivative (TD), the theta map (TM), the horizontal derivative of tilt angle (HTD), and the normalized total horizontal derivative (NHD). HD and VD showed average good performance for a single-body model, but failed to detect multiple bodies. AS traced the edge for a single-body model comparatively well, but it was unable to detect an angulated corner and multiple bodies at the same time. TD and TM performed well in delineating the edges of shallower and larger bodies, but they showed relatively poor performance for deeper and smaller bodies. In contrast, they had a significant advantage in detecting the edges of multiple bodies. HTD showed poor performance in tracing close bodies since it was sensitive to an interference effect. NHD showed great performance under an appropriate window.

• Journal of The Korean Association For Science Education
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• v.20 no.1
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• pp.112-136
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• 2000

In this study, literatures concerning the scientifically gifted/talented were identified through exploration of ERIC(Education Research Information Center) and then categorized. Existing educational programs for the scientifically gifted/talented were analyzed to aid in development and progress of education program of the scientifically gifted/talented. The followings are the results of this study 1. Exploration of ERIC from 1981 to 1997 showed 150 documents related to the scientifically gifted/talented and of those found there were 63 scientifically gifted/talented education program documents which accounts for 42.0%. 2. 42.0% of documents related to the scientifically gifted/talented and 65.1% of education program for the scientifically gifted/talented were in the publication type of journal articles. 3. 60.0% of documents related to the scientifically gifted/talented and 68.3% of education program for the scientifically gifted/talented were in the type of paper of reports. 4. 71.4% of education programs for the gifted/talented was centered around scientifically gifted/talented students in middle or high school. 5. 52.4% of education programs for the scientifically gifted/talented was being carried out as an supplementary enrichment education program such as summer programs or short term projects. Education programs for the scientifically gifted/talented carried out as a regular class accounted for 38.1%. 6. Systems like Mentorship System and Internship System is being well carried out due to good interrelationships between universities and institutions. There were many programs encouraging majors and careers in science related fields. 7. Individualized education, which is effective in teaching the scientifically gifted/talented whose abilities, interests, and attitudes differ, is being well carried out.

• Geophysics and Geophysical Exploration
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• v.9 no.3
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• pp.241-249
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• 2006

Due to the long tectonic history and the very complex geologic formations in Korea, the anisotropic characteristics of subsurface material may often change very greatly and locally. The algorithms commonly used, however, may not give sufficiently precise computational results of traveltime data particularly for the complex and strong anisotropic model, since they are based on the two-dimensional (2D) earth and/or weak anisotropy assumptions. This study is intended to develope a three-dimensional (3D) modeling algorithm to precisely calculate the first arrival time in the complex anisotropic media. Considering the complex geology of Korea, we assume 3D TTI (tilted transversely isotropy) medium having the arbitrary symmetry axis. The algorithm includes the 2D non-linear interpolation scheme to calculate the traveltimes inside the grid and the 3D traveltime mapping to fill the 3D model with first arrival times. The weak anisotropy assumption, moreover, can be overcome through devising a numerical approach of the steepest descent method in the calculation of minimum traveltime, instead of using approximate solution. The performance of the algorithm developed in this study is demonstrated by the comparison of the analytic and numerical solutions for the homogeneous anisotropic earth as well as through the numerical experiment for the two layer model whose anisotropic properties are greatly different each other. We expect that the developed modeling algorithm can be used in the development of processing and inversion schemes of seismic data acquired in strongly anisotropic environment, such as migration, velocity analysis, cross-well tomography and so on.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.207-212
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• 2008

Bathymetry, side scan sonar, and magnetic survey data for the summit area of Dokdo obtained by Korea Ocean Research & Development Institute in 1999, 2004, and 2007 were analyzed to investigate the geophysical characteristics of the summit. Bathymetry and topographic data for the summit of Dokdo show uneven seabed and irregular undulations from costal line to -90 m in water depth, indicating the effects of partial erosions and taluses. The stepped slope in the bathymetry is supposed to be a coastal terrace suggesting repetition of transgressions and regressions in the Quaternary. The bathymetry and the side scan sonar data show a small crater, assumed to be formed by post volcanisms, at depth of $-100\;{\sim}\;-120\;m$ in the northeastern and the northwestern parts of the survey area. Except some areas with shallow sand sedimentary deposits, there are rocky seafloor and lack of sediments in the side scan sonar images of the survey area, dominantly. The analytic signal of the magnetic anomaly coincides with other geophysical results regarding to the location of the residual crater. The geophysical constraints of the summit of Dokdo propose that the islets and the rocky seabed elongated northeastward and northwestward from the islets might be the southern crater of the Dokdo volcano.

• Journal of the Korean Geophysical Society
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• v.5 no.3
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• pp.233-245
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• 2002

The spectral-analysis-of-surface-waves (SASW) method is a nondestructive testing method based upon generation and detection of elastic stress waves. SASW is widely used as one of the techniques to determine stiffness profile in engineering geophysics. The essential steps involved are construction of an experimental dispersion curve from data collected in situ, and inversion of the dispersion curve to determine the stiffness profile. The main object of this study is to derive an analytical Jacobian for the inversion. If we set the subsurface to N homogeneous layer, it could save 2N times Jacobian calculation compared to numerical jacobian calculation during inversion. To reconstruct a stiffness profile, constrained damped least square method was applied for the inversion. The algorithm was tested for the numerical data and for the real asphalt and tunnel data, which were able to verify the stiffness profile. The stiffness profile reconstructed by the algorithm showed the possibility to appraise the soundness of tunnel with applications SASW.

• Journal of the Korean earth science society
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• v.30 no.1
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• pp.49-57
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• 2009

We studied a structure of the Kunsan basin in the Yellow Sea using ship-borne magnetic data and altimetry satellite-derived gravity data provided from the Scripps institution of oceanography in 2006. The gravity data was analyzed via power spectrum analysis and gravity inversion, and the magnetic data via analytic signal technique, pseudo-gravity transformation, and its inversion. The results showed that the depth of bedrock tended to increase as we approached the center of the South Central Sag in Kunsan basin and that the maximum and minimum of its depth were estimated to be about 6-8 km and 2 km, respectively. Inaddition, the observed high anomaly of gravity and magnetism was attributed to the intrusion of igneous rock of higher density than the surrounding basement rock in the center of South Central Sag, which was consistent with the interpretation of seismic data obtained in the same region.

• Journal of the Korean Society of School Health
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• v.9 no.2
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• pp.249-266
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• 1996

AIDS and the spectrum of Human Immunodeficiency Virus(HIV) infections present a monumental challenge to the health of the Korean public. In response to this special challenge, I think public education and voluntary behavior changes are the most effective measures to fight the spread of the disease. Adolescents represent a critical risk group for prevention and intervention programming. Research indicates sexually active adolescents, homosexual contact, illicit drug use are an gradually increasing. These characteristically adolescent risk-taking behaviors suggest the need for schools and communities to mobilize intervention strategies. Schools are highly efficient ways to reach a majority of young people in Korea with HIV prevention programs. These programs include substantial attention to sexual and drug use behaviors with the long term objective of a multidimensional school health program. Information resulting from risk behavior surveillance activities and guidance on school health curricula is particularly useful. What is needed for adolescents is a revamping of education to give students the critical thinking and analytic skills that allow them to apply knowledge, make decisions, and think independently. The best HIV preventive education provides young people with opportunities to learn and practice just those skills. In the early stages of HIV education were focused solely on information. Providing information is easy but unfortunately, behavior change is not that simple to activate. Information must be combined with values exploration and skilly building, including responsible decision making, negotiation, refusal, and critical thinking skills. The same knowledge, attitudes and skills needed for effective HIV prevention also prevent or reduce other risks, including other sexually transmitted diseases, unwanted pregnancies, and alcohol or other drug use. The role of other youth serving organizations in HIV prevention is also important: parental and youth involvement is needed; it's important to presidential and governament leadership is essential to prevention education; promote integrated adolescent programs, to enhance health and education sector collaboration; and of course, we need to expand research on adolescent health and engage the media in health promotion. Among these changes, a school-based systematic health education of AIDS is certainly one of the essentials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2251-2258
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• 2012

This study compared the unweighted sample design, frequency weighted sample design and complex sample design to using 2009 Korea National Health and Nutrition Examination Survey in an effort to identify whether or not there is any difference in potential risk factors. Pearson chi-square test and Rao-scott chi-square test were applied to the analytic methods. As a result of analyses, all the variables were overestimated as significant risk factors in case of the unweighted sample design to which only the frequency weights were applied. In addition, there were differences in the confidence levels and results from the simple random sampling analysis and complex sample design to which no weight was applied. It is necessary to carry out the complex sample design rather than the analysis to which the frequency weights are applied, in order to ensure the findings to represent the whole population when our national statistics data is used.

• Journal of Digital Convergence
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• v.13 no.3
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• pp.255-261
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• 2015

The use of games using smartphones have become universal, and the market share of MMORPG among various game genres shows an uptrend. However, MMORPG requires complex interface in view of the genre characteristics, and therefore, there are difficulties in building interface for efficient game play. This study analyzed game interface characteristics to suggest MMORPG game interface suitable for the mobile environment, and carried out a questionnaire survey evaluation on the usability of fight, exploration, character and transaction interfaces targeting 12 users. To quantitatively evaluate the subjective questionnaire survey results, this study analyzed a correlation between the characteristics of game interface and popularity using AHP. As a result, there was a close correlation between game selection & popularity and interface, and this study ascertained that interface development through game interface usability evaluation using AHP was possible.

• Healthcare Informatics Research
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• v.24 no.4
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• pp.253-262
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• 2018

Objectives: We reviewed digital epidemiological studies to characterize how researchers are using digital data by topic domain, study purpose, data source, and analytic method. Methods: We reviewed research articles published within the last decade that used digital data to answer epidemiological research questions. Data were abstracted from these articles using a data collection tool that we developed. Finally, we summarized the characteristics of the digital epidemiological studies. Results: We identified six main topic domains: infectious diseases (58.7%), non-communicable diseases (29.4%), mental health and substance use (8.3%), general population behavior (4.6%), environmental, dietary, and lifestyle (4.6%), and vital status (0.9%). We identified four categories for the study purpose: description (22.9%), exploration (34.9%), explanation (27.5%), and prediction and control (14.7%). We identified eight categories for the data sources: web search query (52.3%), social media posts (31.2%), web portal posts (11.9%), webpage access logs (7.3%), images (7.3%), mobile phone network data (1.8%), global positioning system data (1.8%), and others (2.8%). Of these, 50.5% used correlation analyses, 41.3% regression analyses, 25.6% machine learning, and 19.3% descriptive analyses. Conclusions: Digital data collected for non-epidemiological purposes are being used to study health phenomena in a variety of topic domains. Digital epidemiology requires access to large datasets and advanced analytics. Ensuring open access is clearly at odds with the desire to have as little personal data as possible in these large datasets to protect privacy. Establishment of data cooperatives with restricted access may be a solution to this dilemma.