• Journal of the Korea Society for Simulation
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• v.20 no.4
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• pp.157-166
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• 2011

As underwater environment monitoring system's interest has increased, the research is proceeding about underwater acoustic sensor network. Underwater sensor network can be applicable to many fields, such as underwater environment monitoring, underwater resource exploration, oceanic data collection, military purposes, etc. It is essential to define the PHY-MAC protocol for revitalization of the underwater acoustic sensor network which is available utilization in a variety of fields. However, underwater acoustic sensor network has to implement by consideration of underwater environmental characteristics, such as limited bandwidth, multi-path, fading, long propagation delay caused by low acoustic speed. In this paper, we define frequency of adjusted PHY protocol, network topology, MAC protocol, PHY-MAC interface, data frame format by consideration of underwater environmental characteristics. We also present system configuration of our implementation and evaluate performance based on our implementation with test in real underwater field.

• Journal of Integrative Natural Science
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• v.9 no.1
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• pp.72-79
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• 2016

Hexane, ethyl acetate and methanol extracts of whole plant of Boerhavia diffusa were screened for phytochemical and biological activities. Qualitative phytochemical screening via colorimetric method and the quantitative estimation of phenolic and flavonoid content were performed. Antioxidant assay using DPPH scavenging method was studied. Antimicrobial screening of plant extracts was done by cup diffusion technique. Cytotoxic activity of B. diffusa was studied by brine shrimp bioassay and anthelminthic activity was evaluated in vitro in Pheretima posthuma. This study revealed B. diffusa as a source of various phyto-constituents such as alkaloids, glycosides, saponins, tannins, carbohydrates, cardiac glycosides, flavonoids and terpenoids. Quantitative estimation of total phenol was found to be maximum in BEE i.e. $29.73{\pm}0.88$, BME $19.8{\pm}2.02$ and in BHE $9.15{\pm}0.304mgGAE/g$. Similarly, the total flavonoid content was found to be $17.44{\pm}0.75$ in BEE, $14.43{\pm}0.23$ in BHE and 3.678 mg QE/g in BME. Ethyl acetate extract showed its antibacterial activity against all tested pathogens except Escherichia coli whereas Staphylococcus aureus and Salmonella Typhi were resistant to methanol and hexane extract. The zone of inhibition (ZOI) of ethyl acetate extract against S. Typhi and B. cereus was found to be 18 mm and 14 mm respectively. The MIC value of BEE in S. Typhi was $3.125{\mu}g/ml$ and in B. cereus was $12.5{\mu}g/ml$. The preliminary screening of anticancer property of B. diffusa i.e. BSLT in methanol was found to be $165.19{\mu}g/ml$. B. diffusa was also found to contain anthelmintic property. The study helped in further exploration of medicinal properties of B. diffusa by phytochemical screening and biological activities paving the path for study and investigation in this plant.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.1
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• pp.33-40
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• 2022

With the recent increase in the development of military drones, they are adopted and used as the combat system of battalion level or higher. However, it is difficult to use drones that can be used in battles below the platoon level due to the current conditions for the formation of units in the Korean military. In this paper, therefore, we developed a program drones equipped with a thermal imaging camera and LiDAR sensor for reconnaissance and exploration that can be applied in battles below the platoon level. Using these drones, we studied the possibility and feasibility of drones for small-scale combats that can find hidden enemies, search for an appropriate detour through image processing and conduct reconnaissance and search for battlefields, hiding and cover-up through image processing. In addition to the purpose of using the proposed drone to search for an enemies lying in ambush in the battlefield, it can be used as a function to check the optimal movement path when a combat unit is moving, or as a function to check the optimal place for cover-up or hiding. In particular, it is possible to check another route other than the route recommended by the program because the features of the terrain can be checked from various viewpoints through 3D modeling. We verified the possiblity of flying by designing and assembling in a form of adding LiDAR and thermal imaging camera module to a drone assembled based on racing drone parts, which are open source hardware, and developed autonomous flight and search functions which can be used even by non-professional drone operators based on open source software, and then installed them to verify their feasibility.

• Journal of the Korea Society of Computer and Information
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• v.28 no.10
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• pp.241-246
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• 2023

The purpose of this study was to suggest the direction of university employment support through analysis of employment success factors for young college graduates and comparison of determining factors in metropolitan and non-metropolitan areas. For this purpose, the factors were analyzed using SPSS 25.0 statistical package binary logistic regression analysis using the 2019 'College Graduate Occupational Movement Path Survey' data provided by the Korea Employment Information Service. As a result of the study, among the personal characteristics of college graduates in Seoul and the metropolitan area, age, parental assets, and language training experience were (+) factors for employment success, and in terms of college characteristics, 2-3 year college graduates were more likely to succeed in employment than 4-year college graduates or education college graduates. In addition, among the personal characteristics of college graduates from non-metropolitan areas, age and parental assets were (+) factors in employment success, and 2-3 year college graduates were more likely to succeed in employment than 4-year college graduates.

• Korean Journal of Social Welfare
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• v.67 no.2
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• pp.85-112
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• 2015

This study examined the relationship structure among personal and social cognitive factors contributing to professional help-seeking decisions to relieve distress of those in low-income, then suggested an appropriate model to inform knowledge for better social work practice. Using data of a purposive sampling from 331 low-income people, covariance structural analyses were conducted in two stages of model exploration, one for TPB model and another for its extended model including the level of distress, family support, and willingness. As results, in the path analyses with the observed variables of the basic components of the TPB, subjective norm showed the strongest effect on the intention, following by attitudes towards help-seeking, then behavioral control the least; in turn both the intention, positively, and behavioral control, negatively, contributed to help-seeking decisions. In the second stage of the path analyses with the extended model of the TPB, each of distress and family support demonstrated direct positive effect on each of attitudes, subjective norm, and behavioral control; each of the attitudes, subjective norm, and behavioral control showed positive effect on both intention and willingness; in turn, while intention showed strong positive effect on help-seeking decisions, willingness had no significant effect and behavioral control had negative effect on decisions. There were significant indirect effects of behavioral control on intention through willingness and of willingness on decisions through intention. These results suggested that the TPB model is useful for modeling help-seeking decisions through personal and social cognitions, especially the significance of subjective norm implied the importance of social cognition for the people in low-income with distress. Further, it was implied that the extended model needs to address particularity of those people in low-income and the mechanism shown by behavioral control and willingness implied the importance of practicing respect for the client's autonomy and will for self-support in social work practice.

• 대한공업교육학회지
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• v.38 no.2
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• pp.114-135
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• 2013

The purpose of this study is to provide base line data for right concept and identity establishment of Specialized Vocational high school, to identify recognition of Specialized Vocational high school, to analyze image of Specialized Vocational high school recognized by middle school student. The population was all middle school third year students in Korea. Using random sampling technique, 50 classes of 61 schools were sampled for the study. A survey questionnaire used Semantic Differential(SD) suggested by Osgood(1957). SD consisted of a number of adjective pairs, finally, this study used 11 adjective pairs to have validity. 1,198 out of 1,441 questionnaire were returned (a return rate of 83.14%), among which 935 were used for the analysis after data cleaning. An alpha level of 0.05 was established a prior for determining significance. All data analysis was accomplished using the SPSS 20.0 Win. Based on the finding of the study, the major results of the this study were as follows : 1. Higher average is female students' image of Specialized Vocational high school than male students' that, but, The difference between the two samples was not statistically significant. 2. It was only 20% that receive career education of Vocational high school. It is necessary to accomplish and expand career education of Specialized Vocational high school for proper career education from middle school, to realize career exploration and decide one's career path based on one's specialty. 3. They have positive images who hope for going on to the Specialized Vocational high school of education than the others. 4. It is necessary to accomplish and expand career education of Specialized Vocational high school for proper career education from middle school, to realize career exploration and decide one's career path based on one's specialty, because the result was statistically significant. 5. They have the more possitive image of Specialized Vocational high school, the more know it, totally.

• Hwankyungkyoyuk
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• v.21 no.1
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• pp.82-96
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• 2008

The primary purpose of this research is to examine the career development of under-graduate environmental education program students. More specifically, it intends to understand how they perceive their career prospect, how they prepare for they career and what kind of career development assistance they receive from their school. For most of college students, a primary purpose for attending college is to prepare for a career, but often academic preparation in college is not enough to get the job they aspire. Career preparation becomes even more complex when their major does not dictate any specific career path or when the major does dictate a specific career path but it does not provide sufficient and quality job opportunities. Undergraduate environmental education programs are typical examples of the latter. To illuminate the understanding of the context surrounding undergraduate environmental education program students, semi-structured interviews were conducted through an instance message software program from August 17th, 2007 to August 20th, 2007. The subjects of this study consisted of 4 undergraduate students and 2 graduates of Hangu University (a tentative name). Each participant was interviewed once or twice for about 2 hours each interview. The findings of the study are as follow. First, they maintain a positive attitude regarding the career outlook and the career decision but it is not well founded. Second, career search and career preparation are conducted individually, and their school does not provide much systematic career assistance. Third, they did not see the relevance of the curriculum of their program to their future career. A few preliminary implications for practices related to career development may be drawn from the findings reported in this study. First, undergraduate students in environmental education programs appear to be in need of comprehensive career development assistance ranging from exploration of job opportunities related to majors, to development of job-seeking skills, to general issues of career preparation and choice. Experiential modes of career exploration seem to be helpful in clarifying their interest and aptitude in the area of environmental education. Second, career development assistance for these students should start at early college years. Third, these students may need help in exploring diverse opportunities related to their major as well as other academic areas. Finally, it is recommended to create more careers in the area of environmental education.

• Geophysics and Geophysical Exploration
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• v.9 no.3
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• pp.207-224
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• 2006

It has been widely known that the seismic piezo-cone penetration test (SCPTu) is one of the most useful techniques for investigating the geotechnical characteristics such as static and dynamic soil properties. As practical applications in Korea, SCPTu was carried out at two sites in Busan and four sites in Incheon, which are mainly composed of alluvial or marine soil deposits. From the SCPTu waveform data obtained from the testing sites, the first arrival times of shear waves and the corresponding time differences with depth were determined using the cross-over method, and the shear wave velocity $(V_S)$ profiles with depth were derived based on the refracted ray path method based on Snell's law. Comparing the determined $V_S$ profile with the cone tip resistance $(q_t)$ profile, both trends of profiles with depth were similar. For the application of the conventional CPTu to earthquake engineering practices, the correlations between $V_S$ and CPTu data were deduced based on the SCPTu results. For the empirical evaluation of $V_S$ for all soils together with clays and sands which are classified unambiguously in this study by the soil behavior type classification index $(I_C)$, the authors suggested the $V_S-CPTu$ data correlations expressed as a function of four parameters, $q_t,\;f_s,\;\sigma'_{v0}$ and $B_q$, determined by multiple statistical regression modeling. Despite the incompatible strain levels of the downhole seismic test during SCPTu and the conventional CPTu, it is shown that the $V_S-CPTu$ data correlations for all soils, clays and sands suggested in this study is applicable to the preliminary estimation of $V_S$ for the soil deposits at a part in Korea and is more reliable than the previous correlations proposed by other researchers.

• Journal of the Korean earth science society
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• v.38 no.4
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• pp.251-262
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• 2017

The system of magnetic exploration with a drone flight was constructed and applied to the iron mine site. The magnetic probe system installed on the drone used a sensor as Bartington's fluxgate type magnetometer, Mag639 and the A/D converter to collect magnetic intensity values on the tablet PC. The drone flight control module is a highly expandable Pixhawk with allowing 15 minutes of flight by loading 3kg. Experiments on the magnetic field interference range were performed to remove the erroneous effect from the drone with applying RTK GPS to obtain the magnetic intensity value at the accurate position. The accurate location information enabled to obtain the gradient measurement of magnetic field by measuring twice at different altitudes. Also, by using the terrain information, we could eliminate the terrain effect by setting the flight path to fly along the terrain. These results are in line with the field experiments using the nuclear proton magnetometer G-858 of Geometrics Co., Ltd, which adds to the reliability of the drone based aeromagnetic survey system we constructed.

• Korean Security Journal
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• no.59
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• pp.133-159
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• 2019

The free semester system, introduced on a trial basis in 2013, has been fully implemented in all middle schools since 2016. The free semester system for middle school students is divided into subject activities and free semester activities with the purpose of students' dream and career exploration. While the activities of various vocational groups linked to subjects during the free semester are discussed, studies on the industrial security career education in middle schools are hard to find. In addition, the career sites that provide diverse information on career path for teachers, students and parents with support from the Ministry of Education have not established any program regarding industrial security. This study aims to look at the status of career education by the analysis of keywords for industrial security in the career experience network currently operated by the Ministry of Education and in-depth interview with career education teachers, students and parents, and industrial security experts. Based on such analysis, this study attempts to figure out a comprehensive understanding of the free semester system and to explore strategies for promoting industrial security education. The results of this study found that the activation plan for industrial security education requires the industry security education through career network, development of industrial security education program, training and placement of professional industrial security lecturer, and establishment of support systems for experience in industrial security.