• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1573-1579
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• 2010

In this paper, we studied efficient design of wireless transmission system for unified data transmission in a subway and railway. It is increased that need of broadband multimedia service to make useful environment for users and to support the operation of railway system. High bandwidth is better if we need more services. But, high bandwidth requires more cost at tunnel of subway. And more bandwidth makes received antenna sensitivity bad. So it needs more wireless stations. We deduced best bandwidth for subway wireless transmission system using the cost of installation and efficiency of system. Consequently, we proposed efficient service model for broadband wireless system at a subway. Subway broadband wireless transmission system is testing and extended to province subway. The cost of subway broadband wireless transmission system is saved, because the system can be efficiently designed using proposed service model. Therefore, the effectiveness of it will be expected to be very big.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.130-137
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• 2013

This research was performed through the experimental design to get the statistical analysis on foamed concrete mixed plaster with hydrogen peroxide. In this experiment, we set the ratio of each material, which part of lightweight concrete, as experimental factors and evaluated on the mechanical properties by statistical analysis for response variables obtained from experiments. Experimental factors are plaster replacement, water binder ratio, and hydrogen peroxide ratio. Response variables are dry density, compressive strength, and flexural strength. Mixing design of the foamed concrete set up a total of 15 experimental points by Box-Behnken (BB) method of the response surface analysis. Thus, the results of a study were summarized as follows. Values of the probability in experimental factors (plaster replacement, water binder ratio and hydrogen peroxide ratio) on the response variables were estimated to be significant at the 95% of confidence limit. On response surface analysis for dry density of foamed concrete, water binder ratio and hydrogen peroxide ratio were estimated to be significant (${\alpha}$ = 0.05), and the relationship between the amount of void and the water content for dry density is inverse proportional. On response surface analysis for the compressive strength of foamed concrete, water binder ratio, hydrogen peroxide ratio and (hydrogen peroxide ratio)$^2$ was estimated to be significant (${\alpha}$ = 0.05). On response surface analysis for the flexural strength of foamed concrete, water binder ratio, hydrogen peroxide ratio was estimated to be significant (${\alpha}$ = 0.05). Through multi response surface analysis, we found the optimal area that meets performance goals.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.552-561
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• 2016

In this experimental study, the dynamic stability derivatives of a tailless lambda-shape UAV are estimated from time history data of aerodynamic moments measured from the internal balance while the test model is forced to oscillate at given frequencies and amplitudes. A 3-axis forced oscillation apparatus is designed to induce decoupled roll, yaw, pitch oscillations respectively. The results show that the roll damping derivatives remain stable at the entire range of angle of attack tested, whereas the pitch damping derivatives become unstable beyond $15^{\circ}$ angle of attack. The amplitude and frequency have little impact on roll damping derivatives while the smaller amplitude and frequency of oscillation improves the pitch stability. The yaw damping derivative values are fairly small as expected for a tailless configuration. The results indicate that the proposed methodology and test apparatus area valid for estimating the dynamic stability derivatives of a tailless UAV.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.105-112
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• 2017

A lot of piping systems have been used from nuclear power systems to water supply systems. The maintenance of the piping systems is needed to ensure proper operation of the piping systems. Failure of the large pipe systems especially such as KDHC(Korea District Heating Corporation) can be a matter directly related to the enterprise productivity and profitability. It can also lead to very important issues in promoting public safety and convenience. Therefore a method of quick and safety repairs have been emerged as the most important problem. In this study, freezing seal isolation method using liquid nitrogen cryogenic refrigerant was developed for the maintenance of a pre insulated heat transport pipe of KDHC with a diameter of 300 mm. In this study, by employing computational analysis techniques we performed the flow and heat transfer analysis for the targeted pre insulated heat transfer pipe and freezing seal jacket(ice-Plug) and have selected for optimal system. The detailed design model based on the results of the computational analysis finally was produced. A laboratory-scale test apparatus were designed and the freezing seal isolation self-test carried out. Also the performance assessment tests in the test bed of KDHC were carried out for on-site application.

• Science of Emotion and Sensibility
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• v.22 no.4
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• pp.15-30
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• 2019

The reduction of traffic accidents is a primary potential benefit of autonomous vehicles (AVs). However, the prevalence of AVs also arouses a key question: to what extent should a human wrest control back from AVs? Specifically, in an unavoidable situation of emergency, should an AV be able to decide between the safety of its own passengers and endangered pedestrians? Should AV programming include well-accepted decision rules about actionsto take in hypothetical situations? The current study (N = 103) examined individual/situational variables that could perform critical decision-making roles in AV related traffic accidents. The individual variable of attitudes toward AVs was assessed using the Self-driving Car Acceptance Scale. To investigate situational influences on decisional processes, the study's participants were assigned to one of two groups: the achievement value was activated in one group and the benevolence value was triggered in the other through the use of a sentence completion task. Thereafter, participants were required to indicate who should be protected from injury: the passengers of the concerned AV, or endangered pedestrians. Participants were also asked to record the extent to which they intended to buy an AV programmed to decide in favor of the greater good according to Utilitarian principles. The results suggested that participants in the "achievement value: driver perspective" groupexpressed the lowest willingness to sacrifice themselves to save several pedestrians in an unavoidable traffic accident. This group of participants was also the most reluctant to buy an AV programmed with utilitarian rules, even though there were significant positive relationships between members' acceptance of AVs and their expressed intention to purchase one. These findings highlight the role of the decisional processes involved in the "achievement value" pertaining to AVs. The paper finally records the limitations of the present study and suggests directions for future research.

• Journal of The Korean Association For Science Education
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• v.35 no.5
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• pp.877-884
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• 2015

Technology is an important means to enhance students' understanding about scientific concepts. In particular, newly introduced 3D printing technology has great potential to help students learn scientific concepts better. 3D printing is a process for a creating physical object with a three dimensional model. In this study, we explored two types of learners' (students vs. adults) motivation and satisfaction with 3D printing technology. With regard to motivation, student learners showed higher task value, self-efficacy for learning, and satisfaction than adult learners. The result implied that 3D printing technology is more effective to student learners than adult learners. In addition, for adult learner group, negative relationship between technology and satisfaction was found. Therefore, support for reducing the technology anxiety for adult learners is necessary. Further discussions are provided for the research and application of 3D printing technology in science classroom.

• Child Health Nursing Research
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• v.20 no.2
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• pp.123-131
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• 2014

Purpose: This study was conducted to examine the effects of simulation education integrated with problem based learning (SIM-PBL) on clinical competency and self-efficacy in post operation nursing care for children. Methods: This study was a quasi-experimental design. Thirty six students in the third year of a 4-year baccalaureate nursing program were recruited conveniently and assigned to the control or intervention groups using time difference. Students were all in a pediatric nursing clinical practicum. The control group received the regular clinical practicum in a hospital setting. For the intervention group, a SIM-PBL education replaced 150 minutes of their clinical practicum. Results: The intervention group showed greater improvement in two areas of clinical competency compared with the control group; physical assessment (t= 3.019, p=.005) and post operation advice (t=2.428, p=.021). However, no statistically significant differences in improvement in any areas of self-efficacy were found between two groups. Conclusion: The results indicate that the SIM-PBL education is effective in improving some areas of clinical competence, but not self-efficacy in post operation nursing care for children. Further study is needed to develop SIM-PBL programs for various clinical topics and evaluate the effectiveness on the learning outcomes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.638-644
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• 2002

In this paper, we implemented a three dimensional image display system using stereogram and holographic optical memory techniques which can store many images and reconstruct them automatically. In this system, to store and reconstruct stereo images, incident angle of reference beam must be controlled in real time, so we used BPH(binary phase hologram) and LCD(liquid crystal display) for controlling reference beam. The reference beams are acquired by Fourier transform of BPHs which designed with SA(simulated annealing)algorithm, and the BPHs are represented on the LCD with the 0.05 seconds time interval using application software for reconstructing the stereo images. And input images are represented on the LCD without polarizer/analyzer for maintaining uniform beam intensities regardless of the brightness of input images. The input images and BPHs are edited using application software(Photoshop) with having the same recording scheduled time interval in storing. The reconstructed stereo images are acquired by capturing the output images with CCD camera at the behind of the analyzer which transforms phase information into brightness information of images. In output plane, we used a LCD shutter that is synchronized to a monitor that display alternate left and right eye images for depth perception. We demonstrated optical experiment which store and reconstruct four stereo images in BaTiO$_3$ repeatedly using the proposed holographic optical memory techniques.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.193-198
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• 2004

In general, the function of intake structure, whether it be a open channel, a fully wetted tunnel, a sump or a tank is to supply an evenly distributed flow to a pump station. An even distribution of flow, characterized by strong local flow, can result in formation of surface or submerged vortices, and with certain low values of submergence, my introduce air into pun, causing a reduction of capacity and efficiency, an increase in vibration and additional noise. This study investigated experimentally the formation of the vortex to understand the mechanism of vortex formation and to prevent the formation of vortex in the sump model using by the model test and PIV tool. Sump model was manufactured to 1/8 scale with the drawing of W intake pumping station. from the results of model test and PIV, the vortex were occurred the in the whole section. Thus, sump model tests with the anti-vortex device might be considered to prevent the formation of vortex in the sump model.

• Journal of Digital Convergence
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• v.15 no.1
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• pp.227-238
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• 2017

Cardiac arrest is a serious intensive emergency disease that causes death within less than several minutes by depriving the body and brain of blood supply. Survival rate of cardiac arrest patients outside of hospitals is especially low. This is because pedestrians usually do not perceive the patient as a sick person, also, even if they do so, they have no medical knowledge to properly react to such emergency. The purpose of this study is to propose a solution that uses widely spread smart phones to alert pedestrians of the cardiac arrest patient, prevents cardiac arrest, and provides first-aid measures. By applying the proposed solution, cardiac arrest can be prevented in advance, pedestrians can be alerted to keep the golden time(4 minutes), and first witness can quickly proceed with CPR, ultimately enhancing the survival rate of the cardiac arrest patient.