• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.2
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• pp.77-85
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• 2000

Simulation of local external forcing and its response in the rotation table experiment has been investigated. Spatially-uniform external forcings have been applied in many experimental studies, however, based on the fact that the north-south distribution of the wind-stress curl and the existence of local maximum of the sea surface heat loss in the northern part of the East Sea, new method of combined effects of local forcings has been employed in separate experiments. Carefully designed local source or sink at the bottom of the cylindrical container can produce horizontal pressure gradient within the Ekman layer, and consequently the interior also attains the same pressure gradient that produces geostrophic interior circulation. In order to keep free surface during the local-surface cooling, a side-wall cooling method is suggested. For the various type of local forcing including the effects local cooling and the periodic change of local wind-stress curl, western-boundary flow in terms of its strength, position of separation from the boundary have been observed.

• The Korean Journal of Pain
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• v.12 no.1
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• pp.87-94
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• 1999

Backgroud: We have performed the CT-guided celiac plexus block (CPB) using anterior approach to evaluate the safety and efficacy of the procedure and to determine the role of CT. Methods: CPB were done in 10 patients (5 men and 5 women: mean age, 58.1 years) with intractable upper abdominal pain due to terminal malignancy of the stomach (n=3), pancreas (n=4), gallbladder (n=2), and liver (n=1). To permit an anterior approach, patients lay supine on the CT scan table during the procedure. One 21-guage Chiba needle was placed just anterior to the diaphragmatic crus between the celiac and superior mesenteric arteries and 10~12 ml of dehydrated alcohol was injected. Degree of pain relief following the procedure was assessed and pain was graded on a numeric rating scale (NRS) from 0 to 10. Results: The results suggest a direct relation between the degree of celiac invasion and the response to the CPB. With CT guidance, it is possible for us to direct the needle into more accurate region, allowing alcohol to be deposited in specific ganglion area. Conclusions: CT-guided CPB using an anterior approach was an easy and effective way of reducing intractable upper abdominal pain due to terminal malignancies. CT-guidance allowed precise needle placement and safe procedure. Careful classification of cases is important to predict the degree of pain relief using the grading system based on the degree of involvement of the celiac plexus.

• Smart Structures and Systems
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• v.18 no.1
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• pp.75-92
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• 2016

The design of a semi-active (SA) control system addressed to mitigate wind induced structural demand to high wind turbine towers is discussed herein. Actually, the remarkable growth in height of wind turbines in the last decades, for a higher production of electricity, makes this issue pressing than ever. The main objective is limiting bending moment demand by relaxing the base restraint, without increasing the top displacement, so reducing the incidence of harmful "p-delta" effects. A variable restraint at the base, able to modify in real time its mechanical properties according to the instantaneous response of the tower, is proposed. It is made of a smooth hinge with additional elastic stiffness and variable damping respectively given by springs and SA magnetorheological (MR) dampers installed in parallel. The idea has been physically realized at the Denmark Technical University where a 1/20 scale model of a real, one hundred meters tall wind turbine has been assumed as case study for shaking table tests. A special control algorithm has been purposely designed to drive MR dampers. Starting from the results of preliminary laboratory tests, a finite element model of such structure has been calibrated so as to develop several numerical simulations addressed to calibrate the controller, i.e., to achieve as much as possible different, even conflicting, structural goals. The results are definitely encouraging, since the best configuration of the controller leaded to about 80% of reduction of base stress, as well as to about 30% of reduction of top displacement in respect to the fixed base case.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.266-274
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• 2005

We have designed photonic crystal based bandpass filters whose characteristics are suitable for WDM communication system. The filters consist of coupled point defect resonators in two-dimensional photonic crystal. The frequency response of coupled resonators has been analyzed by the coupling of modes in time, from which the design parameters for the coupled resonator filters have been extracted. For the appropriate choice of the design parameters, each resonator is treated as a lumped L-C resonance circuit, and from the analogy between the equivalent circuit and the standard L-C filter circuits, the design parameters are simply determined from the table for general filter circuit design. Based on the determined design parameters, a photonic crystal based filter has been designed and its performance has been calculated using the finite-difference time-domain method. The designed filter shows a pass band of 50GHz and 0.5 dB in-band ripple, which is suitable for typical WDM communication systems with 100GHz channel spacing.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.6
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• pp.23-32
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• 2007

This study developed an analytical model for predicting nonlinear behavior of PT flat plate frames having slab-column connections with and without slab bottom reinforcement passing through the column. The developed model can predict the failure sequence until punching failure occurs. For verifying the analytical model, the test results of PT flat plate slab-column connections were compared with the results of the analysis. Moreover, the results of static pushover test and shaking table test of 2 story PT flat plate frame were compared with analysis results. For evaluating seismic performance of PT flat plate frame, this study conducted nonlinear response history analysis of the 2 story PT flat plate frame with and without slab bottom reinforcement passing through the column under 1940 El Centro ground motion scaled to have pseudo spectral acceleration of 0.3, 0.5, and 0.7g at the fundamental period of the frame. This study observed that as ground motion is more intense, seismic demands for the frame having the connections without slab bottom reinforcement passing through the column are larger than those without slab bottom reinforcement.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.693-701
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• 2020

In this paper, SQL statements are analyzed to improve database performance in the current course registration system. The performance of the current database was measured through the execution plan of the SQL statements used in the transactions related to the course registration. Through the SQL analysis, the complemented SQL statements confirmed the improved performance. Overall, the performance of the course registration database system was improved through the analysis of the execution plan, and some improvement methods of the course registration SQL were shown as test results. The improved method is to reorganize the tables and index tables related to the course registration through database tuning, and utilize the SQL function to implement an optimized system that has evolved into a course database system with improved performance. The enrollment system re-adjusted by the proposed method showed excellent results in terms of performance compared to the previous enrollment system, and the integrated performance test result reduced the response time by 1.8 to 18 times.

• Journal of Ecology and Environment
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• v.29 no.4
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• pp.323-330
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• 2006

We investigated the impact of watermelon grafted onto Cucumber Green Mottle Mosaic Virus (CGMMV)-resistant transgenic watermelon rootstock on insects as non-target organisms in a greenhouse in 2005. We quantitatively collected insect assemblages living on leaves and flowers, and we used sticky traps to collect alate insects. We compared the patterns of insect assemblages and community composition, cotton aphid (Aphis gossypii Glover) on watermelon leaves and western flower thrip (Frankliniella occidentalis Trybom) on watermelon male flowers, between CGMMV-resistant transgenic watermelon (TR) and non-transgenic watermelon (nTR). Non-parametric multidimensional scaling (NMS) ordination verified that insect assemblages on leaves and sticky traps were different between TR and nTR (P<0.05). The insect assemblages on male flowers were not statistically significant. Multi-response permutation procedures proofed our results from NMS results (P>0.05). Conclusively, TR watermelons appear to have some adverse effects on the population of cotton aphids on leaves and sticky traps, but watermelon male flowers do not show an adverse effect. Further research is required to assess the effect of TR on the aphid and western flower thrip. Life table experiments might support the specific reason for the adverse effects from leaf assemblages. Assessment of non-target impacts is an essential part of the risk assessment of non-target insects for the impact of transgenic organisms.

• Journal of the Korean Institute of Educational Facilities
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• v.27 no.2
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• pp.69-78
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• 2020

Interest in the school environment design is increasing as the project to restructure school space and to become common in school through smart devices. However, no research has been presented on the current status of studies on school environmental design, and the need for analysis of recent research trends in school environmental design is required. In response, this study aims to provide basic data on school environmental design by analysing the trends of domestic studies of school environmental design since 2010 and to present the direction of research on future school environmental design. A total of 312 papers related to school architecture and spatial design are set for study in the results of academic information search on school environmental design. Based on this, frequency analysis and cross-sectional analysis are conducted based on the classification table according to the year of issue, research subject, research purpose, and research method. The statistical significance of the research subjects was secured in accordance with the year of issue and subject to study, and accordingly the key research key words were derived. It is meaningful that through this study, the current status of school environmental design research over the last 10 years can be analyzed and the direction for the future school environmental design research has been suggested.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.1
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• pp.81-90
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• 2002

This paper presents an Implementation of digital high-performance position sensorless control system of Reluctance Synchronous Motor(RSM) drives with Direct Torque Control(DTC). The system consists of stator flux observer, speed and torque estimator, two digital hysteresis controllers, an optimal switching look-up table, Insulated Gate Bipolar Transistor(IGBT) voltage source inverter, and TMS320C31 DSP board. The stator flux observer Is based on the combined voltage and current model with stator flux feedback adaptive control of which inputs are current and voltage sensed on motor terminal for wide speed range. In order to prove the suggested sensorless control algorithm for industrial field application, we have some simulation and actual experiment at low and high speed range. The developed high-performance speed control by fully digital system are shown a good response characteristic of control results and high performance features using 1.0[kW] RSM having 2.57 reluctance ratio of $L_d/L_q$.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.4
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• pp.226-230
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• 2007

In the conventional desktop PC environment, keyboard and mouse are used to process the user input and monitor displays the visual information as an output device. In order to manipulate the digital information, we move the virtual cursor to select the desired graphical icon on the monitor The cursor represents the relative motion of the physical mouse on the desk. This desktop metaphor does not provide intuitive interface through human sensation. In this paper, we introduce a novel tangible interface which allows the user to interact with computers using a physical tool called "Smartpuck". SmartPuck system bridges the gap between analog perception and response in human being and digital information on the computer. The system consists of table display based on a PDP, SmartPuck equipped with rotational part and button for the user's intuitive and tactile input, and a sensing system to track the position of SmartPuck. Finally, we will show examples working with the system.