• Journal of Power Electronics
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• v.16 no.2
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• pp.631-642
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• 2016

Usually, the output characteristics of a photovoltaic (PV) array are significantly affected by non-uniform irradiance which is caused by ambient obstacles, clouds, orientations, tilts, etc. Some local maximum power points (LMPP) in the current-voltage (I-V) curves of a PV array can result in power losses of the array. However, the output power at the global maximum power point (GMPP) is different in different interconnection schemes in a PV array. Therefore, based on the theoretical analysis and mathematical derivation of different topological structures of a PV array, this paper investigated the output characteristics of dual series PV arrays with different interconnections. The proposed mathematical models were also validated by experimental results. Finally, this paper also concluded that in terms of performance, the total cross tied (TCT) interconnection was not always the optimal structure, especially in a dual series PV array. When one of the PV modules was severely mismatched, the TCT worked worse than the series parallel (SP) structure. This research can provide guidance for switching the interconnection to gain the greatest energy yield in a changeable- structure PV system.

• Korean Journal of Community Nutrition
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• v.16 no.4
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• pp.426-438
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• 2011

This study set out to investigate the effects of 16-week nutrition education and exercise intervention run by a public health center on the physical activities and dietary patterns of obese children at the before, after, and after one month point. After the program, the obese index of the obese children dropped by 5.9% from 38.4% to 32.5%. One month after the end of the program, their obese index increased by 1.4% to 33.9% (p < 0.001). The obese children's hours of walking of physical activities increased to 2.6 hours from 1.2 hours after the program and remained at the 2.6 hours range one month after the end of the program (p < 0.01). The total scores of their food habits increased to 10.4 points from 9.1 points after the program and 10.3 points one month after the end of the program with significant differences (p < 0.01). The total scores of their eating behavior made a significant increase to 6.5 points from 5.3 points after the program and then dropped to 5.9 points one month after the end of the program (p < 0.05). As for changes to their dietary pattern scores according to the obese index, only the food habits scores showed significant main effects of term (p < 0.05). According to these results, there is still a need to develop proper programs to help them increase regular exercise, improve their physical activities by cutting down time with TV, computer, Internet, and video games, and enhance their nutritional knowledge and to provide them with ongoing management and guidance until the improved food habits and eating behavior become part of their habits.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.613-620
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• 2011

In order to perform scientific evaluation of dredge results, it is needed to construct the system which is able to manage and evaluate the work process by monitoring in real-time the dredge process such as dredge ship position, dredge depth and dredge volume. This research aims to develop the hydrographic dredge surveying system adding water depth measurement method to both precise positioning and navigation methods using GPS, which allows a high rate of measurement and long distances between the control point and dredging points, operate in all weather conditions, and does not require line of sight to points. We constructed Beacon DGPS-based hydrographic dredger guidance and position management system and developed the operation program which makes the dredge operation perform as monitoring work situation in real-time. It is expected that this developed system will be able to contributes to reducing ultimately the cost in hydrographic dredging or hydrographic construction industries.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.3
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• pp.68-73
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• 2014

Research is being carried out at Korea Aerospace Research Institute with aim of design a HALE UAV(High Altitude Long Endurance Unmanned Air Vehicle). HALE UAVs are ideally suited to provide surveillance, remote sensing and communication relay capabilities for both military and civilian applications. HALE UAVs typically cruise at an altitude between 15 km and 20 km, travelling at low speed and circling specific area of interest. Airframe structural point of view, weight reduction of the airframe structure is the most important method to improve the flight efficiency. High modulus CFRP(Carbon Fiber Reinforced Polymer) has been used in designing the structure in order to minimize the airframe weight. With respect to structural design and analysis, the key question is to decide an adequate airworthiness certification base to define suitable load cases for sizing of various structural components. In this study, FAR(Federal Aviation Regulation) 23 have constituted the guidance and benchmark throughout all structural studies. And the MSC/FlightLoads was introduced to analyze the flight loads for the HALE UAV. The MSC/FlightLoads can compute the flexible air load and analyzed loads are distributed on structural model directly. A preliminary structural concept was defined in accordance with the estimated inertial and aerodynamic loads. A FEM analysis was carried out using the MSC/Nastran code to predict the static and dynamic behaviour of UAV structure.

• The Journal of Korean Obstetrics and Gynecology
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• v.31 no.3
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• pp.79-96
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• 2018

Objectives: The objective of this study was to survey the performance of postpartum care and compare the western medicine and Korean medicine according to women's postpartum disease. The purpose of this study was to provide basic data for the prevention and management of postpartum disease. Methods: The subjects were 228 women who experienced postpartum disease. This research was conducted in G city, at outpatient department of western medicine hospital and Korean medicine hospital. The degree of performance of postpartum care was measured on a 4-point scale divided by each area, and was compared in three groups. Results: Postpartum care includes traditional postpartum care and postpartum care in hospitals. The degree of performance of postpartum care means that the higher the score, the better. The traditional postpartum care performance score was 2.35 and the postpartum care performance score at the hospital was 1.63. The results of this study showed that the performance of traditional postpartum care was higher than that of postpartum care administered in hospitals. The perception of traditional postpartum care methods was 'An indispensable postpartum care method for health' (75.9%). The most effective method of postpartum care was 'consolidate in harmony traditional postpartum care and guidance of the medical team' (88.2%). Conclusions: The improvement and satisfaction degree of postpartum care were higher in Korean medicine than in western treatments. Therefore, the most efficient method of postpartum care must be integrated in harmony with the direction of the medical staff and traditional methods of postpartum care.

• Journal of Aerospace System Engineering
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• v.11 no.1
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• pp.14-21
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• 2017

A Linear parameterized Sigma-Pi neural network (SPNN) is applied to a tilt-duct unmanned aerial vehicle (UAV) which has a very large longitudinal stability ($C_{L{\alpha}}$). It is uncontrollable by a proportional, integral, derivative (PID) controller due to heavy stability. It is shown that the combined inner loop and outer loop of SPNN controllers could overcome the sluggish longitudinal dynamics using a method of dynamic inversion and pseudo-control to compensate for reference model error. The simulation results of the way point guidance are presented to evaluate the performance of SPNN in comparison to a PID controller.

• Journal of the Korea Institute of Building Construction
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• v.20 no.1
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• pp.103-112
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• 2020

In Korea, local government officials are in charge of buildings, and as such are supposed to review submitted documents related to the architectural administration to ensure that they comply with the legal standards. However, these officials generally put a greater emphasis on the preparation of the set of documents required for the administrative work than the content the documents contain. For this reason, many experts point out that the shortage of officials specialized in buildings and construction, as well as the lack of expertise among the building officials in the local governments, may result in repeated safety accidents during building construction. The purpose of this study is to propose the operational direction of a Regional Building Safety (RBS) center to secure the performance and safety of buildings by utilizing private resources. In this study, we carried out a pilot project to verify the effects of an RBS center and to derive the specific number of experts required. As a result, the technical matters were resolved in approximately 15% of the total cases of the document processing procedure, and the level of technical specialization among the officers has also been improved through the provision of guidance. The research findings support the validity and effects of the introduction of the RBS center. Finally, this study proposes (1) the types of RBS Centers that should be established, (2) the roles and business scope of the RBS Center, (3) the specific number of experts required, (4) the qualifications of the experts, and (5) the business regulations of the RBS Center.

• Journal of Gifted/Talented Education
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• v.19 no.1
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• pp.119-140
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• 2009

This paper examined its possibility and made its new definition by finding relevant bases in order to make a close inquiry into its Identity and direction at this point when cyber-based gifted education academy is established and operated again by its necessity And 4 models which can be used in special education for the gifted were developed making a link with special education for the gifted by collecting and re-classifying cyber educational methods developed by basic research as priority of the educational method which is considered to be the most urgent issue in practical cyber learning. It is a project-type cooperation education model, an information collection-type research education model, a community-type discussion education model, and a problem focus-type e-PBL education model. To apply developed leaching-learning models to reality, students at gifted education academy in Gyeonggi Cyber Gifted Province were imputed models in different ways respectively for 4 months. As a result of analysis and statistical data of activity level and satisfaction level of students who participated in learning activity, it appeared that high level of satisfaction and active activity level were induced compared to the previous method based on tasks. It is expected that this paper will provide the bases when each cyber-based gifted education academy plans operation plan later on, and it will provide proper methods when cyber guidance teachers plan class activities.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.33-37
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• 2006

Since 1993, the civil aviation community through RTCA (Radio Technical Commission for Aeronautics) and the ICAO (International Civil Air Navigation Organization) have been working on the definition of GNSS augmentation systems that will provide improved levels of accuracy and integrity. These augmentation systems have been classified into three distinct groups: Aircraft Based Augmentation Systems (ABAS), Space Based Augmentation Systems (SBAS) and Ground Based Augmentation Systems (GBAS). The last one is an implemented system to support Air Navigation in CAT-I approaching operation. It consists of three primary subsystems: the GNSS Satellite subsystem that produces the ranging signals and navigation messages; the GBAS ground subsystem, which uses two or more GNSS receivers. It collects pseudo ranges for all GNSS satellites in view and computes and broadcasts differential corrections and integrity-related information; the Aircraft subsystem. Within the area of coverage of the ground station, aircraft subsystems may use the broadcast corrections to compute their own measurements in line with the differential principle. After selection of the desired FAS for the landing runway, the differentially corrected position is used to generate navigation guidance signals. Those are lateral and vertical deviations as well as distance to the threshold crossing point of the selected FAS and integrity flags. The Department of Applied Science in Naples has create for its study a virtual GBAS Ground station. Starting from three GPS double frequency receivers, we collect data of 24h measures session and in post processing we generate the GC (GBAS Correction). For this goal we use the software Pegasus V4.1 developed from EUROCONTROL. Generating the GC we have the possibility to study and monitor GBAS performance and integrity starting from a virtual functional architecture. The latter allows us to collect data without the necessity to found us authorization for the access to restricted area in airport where there is one GBAS installation.

• Journal of Welding and Joining
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• v.24 no.3
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• pp.27-33
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• 2006

Structural stress approach is well known as a mesh-size insensitive fatigue assessment method by using finite element analyses. It is, however, difficult to estimate the structural stress (SS) at weld end points due to stress singularities when shell elements are used. In this study, fatigue evaluations with longitudinal load carrying box fillet weldment under out-of-plane bending load have been performed by using virtual node method (VNM) in order to avoid the problem, which is called the weld end effect. Various combinations of virtual node parameters, such as reference point and virtual node locations, are investigated for the estimation of proper structural stress values applying VNM in a systematic manner. The appropriate guidance of virtual node parameter has been offered for the fillet weldment considered in the study. The structural stress values obtained by VNM have also been validated by comparing the result with finite element model including weld bead. Moreover, the fatigue strength of the fillet weldment based on the equivalent structural stress is shown to be consistent with the master S-N curve.