• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.3
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• pp.293-300
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• 2009

The rotorcraft-based unmanned aerial vehicle(UAV) capable of performing close-range surveillance and reconnaissance has been developed. Trade studies on mission feasibility led to the adoption of a coaxial rotorcraft with twin rotors counter-rotating in one axis and driven by electric motors. A commercial off-the-shelf flight control computer(FCC) and a radio frequency modem were adopted for autonomous navigation. In order to achieve an aerial view, commercial charge-coupled device camera was also integrated into the vehicle. The performance of the completed vehicle was proved with manual flight test, and mission capability was verified through waypoint navigation flight after being equipped with FCC. This paper treats the whole process of design and system integration for development of the coaxial rotorcraft UAV.

• Journal of People, Plants, and Environment
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• v.24 no.6
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• pp.595-608
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• 2021

Background and objective: For effective horticultural education, it is required to develop kits for practice. In this study, we developed a horticultural kit for germination that introduces storytelling, characterization, and assembly, and investigated the educational effects of using it to study its educational differentiation and usefulness. Methods: First, we developed a seed germination kit for learning. It consists of three components: the kit main frame for hydroponics, the activity sheet for storytelling, and the instruction manual. It is made into an acrylic assembly in consideration of the ease of delivery for contactless learning. Second, we developed two programs, each using a germination kit for horticultural education (experimental group) and a general germination kit program (control group). At this time, the class consists of pre-questionnaire, the 1st and 2nd classes, observation log writing (total six times for two weeks), the 3rd class, and post-questionnaire. The experimental group and control group were separately executed. Third, the application results were compared and analyzed before and after class. As a quantification questionnaire, the effects before and after class were compared through t-test with a questionnaire on program satisfaction and attitude change toward plants. The quantitative results were analyzed through observation activity sheets and effects before and after the class were analyzed through t-test with quantification and language coding. Results: The effect of horticulture education using the developed kit was estimated by a quantification questionnaire. Both the program satisfaction and the change in attitude toward plants showed high in the experimental group, and this difference was statistically significant (p < .05). As a result of analyzing the observation paper with a qualitative questionnaire, various cognitive and affective expressions appeared in the experimental group as well as the contents of the observation paper. The number of syllables and various qualitative expressions appeared, and these differences were also statistically significant (p < .05). Conclusion: Compared to general germination activities, it was found that the germination activities using storytelling-based horticultural kits would be effective for contactless classes in the post-COVID-19 era and in increasing the educational effect of horticultural activities.

• Journal of the Korean School Mathematics Society
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• v.18 no.4
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• pp.431-448
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• 2015

Elementary school teacher selection test has to be implemented for knowledge(MKT) to estimate and to be a step in the expansionary direction. For this, It has to be analyzed closely in terms of teacher's MKT first that questions set from selection tests until now. In this research, some standards were established by type of question, grade, contents field and subject from 84 mathematics questions set at examinations. And it was analyzed concretely by general tendency and produced the results of analysis related to elementary teacher's MKT in elementary school teacher selection test since year 2000. The results showed that descriptive and short answer type was mostly set(71.4%) in type of question and integrated grade type was mostly set(41.7%) in type of grade in elementary school teacher selection test. And in type of contents field, rated from highest to lowest, number and operations(31.0%), measurement(23.8%), figure(15.5%) were set. Textbook/manual(34.5%), solution of problem(26.2%), learning psychology(13.1%) in status of subject were followed in order, but there's no relationship with estimation. This research was based on a standard of precedent study and made an analysis of elementary mathematics questions of selection test since year 2000. Therefore, it has a meaning because of produced results from analysis related to elementary teacher's MKT.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.3
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• pp.199-207
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• 2013

In hydrographic survey, data surveyed with multibeam system includes various errors due to multiple factors. These are corrected by a calibration called patch test, and if existing method is used, the test needs to be conducted for about 8 times for precise system calibration. For more prompt and precise multibeam system calibration, the exact offset of a ship was determined using terrestrial laser scanning and TS surveying, which was used as the initial input for the patch test. In the result, the error of closure was 0.001 m or less for TS surveying and backsight error was 0.005 m or less for scanning. All the surveying data based on the same local coordinate was converted into vessel reference coordinate during which R-square for all rotation angles was 0.99 or higher and standard deviation was 0.008 m or less. Finally, in a patch test using calculated offset of sensors and motion sensor offset, the offset of MBES transducer satisfied manual on hydrography only with 1-time calibration. With these results, it is thought that terrestrial laser scanning and TS surveying can fully be utilized for multibeam system calibration.

• Journal of the Korean Geotechnical Society
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• v.23 no.5
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• pp.111-129
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• 2007

The standard construction manual of the SDA(Separated Doughnut Auger) piling method was proposed so that the resisting capacity of the augered piles could work effectively. 405 dynamic pile load tests and 30 static pile load tests were performed for 265 test piles, which were installed by the SDA piling method in 33 sites in Korea. The results of the pile load tests showed that the end bearing capacity of the SDA augered piles depended on the property of various soil stratums and did not agree with ones estimated by the existing formula based on several standard design codes. On the basis of the pile load test results, four formulas were presented according to bearing stratums to estimate quantitatively the unit end bearing capacity of the SDA augered piles. The formulas for the unit end bearing capacity of piles on soils or weathered rocks were related to N-value given by SPT(Standard Penetration Test), while the unit end bearing capacity on bedrock was suggested to be more than 1500 $tf/m^2$. The presented formulas were compared with the existing formulas, which were presented by several standard design codes to design the augered piles. In order to use correctly the presented formulas, the quality of Standard Penetration Test should be controlled precisely. Also it is desirable to choose a pilot construction site, where both dynamic and static pile load tests are performed.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.3
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• pp.301-306
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• 2008

Drivers are becoming more fatigued and uncomfortable with increase in traffic density, and this condition can lead to slower reaction time. Consequently, they may face the danger of traffic accidents due to their inability to cope with frequent gear shifting. To reduce this risk, some drivers prefer automatic transmission (AT) over manual transmission (MT). The AT offers more superior drivability and less shifting shock than the MT; therefore, the AT market share has been increasing. The AT is controlled by an electronic control unit (ECU), which provides better shifting performance. The transmission control unit (TCU) is a higher-value-added product, so the companies that have advanced technologies end to evade technology transfer. With more cars gradually using the ECU, the TCU is expected to be faster and more efficient for organic communication and arithmetic processing between the control systems than the l6-bit controller. In this paper, the model of an automatic transmission vehicle using MATLAB/Simulink is developed for the Hardware in-the-Loop (HIL) simulation with a 32-bit embedded system, and also the AT control logic for shifting is developed by using MATLAB/Simulink. The developed AT control logic, transformed automatically by real time workshop toolbox, is loaded to a 32-bit embedded system platform based on Freescale's MPC565. With both vehicle model and 32-bit embedded system platform, we make the HIL simulation system and HIL simulation of AT based on real time operating system (RTOS) is performed. According to the simulation results, the developed HIL simulator will be used for the performance test of embedded system for AT with low cost and effort.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.2
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• pp.107-111
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• 2011

The release of a site and building from regulatory control is the final stage of the decommissioning process. The MARSSIM (Multi-Agency Radiation Survey and Site Investigation Manual) provides overall framework for conducting data collection for a final status survey to demonstrate compliance with site closure requirements. The KAERI carried out establishing a final status survey by using the guidance provided in the MARSSIM for of a site and building of the Korea Research Reactor. The release criteria for a site and building were set up based on these results of the site specific release levels which were calculated by using RESRAD and RESRAD-Build codes. The survey design for a site and building was classified by using the survey dataset and potential contamination. The number of samples in each survey unit was calculated by through a statistical test using the collected data from a scoping and characterization survey. The results of the final status survey were satisfied the release criteria based on an evaluation of the measured data.

• PNF and Movement
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• v.16 no.3
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• pp.317-332
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• 2018

Purpose: Patients with tibial fractures can have functional problems with balance and gait, as well as lower extremity muscle weakness. This case report aimed to describe the effect of hip joint strengthening exercises using proprioceptive neuromuscular facilitation (PNF) on balance and gait and lower limb function in a patient with tibia fracture. Methods: One patient diagnosed with tibial fracture was treated for seven weeks with the basic procedure, pattern, and technique of PNF for a hip joint strengthening exercise. Results: The results of pre- and post-intervention treatment showed improvements in physical function and structure in the clinical tests, including the manual strength test; the modified Ashworth scale; sensory evaluation; balance, sit-to-stand, and gait performance; and evaluation of lower limb function. Conclusion: Based on the results of this study, it is suggested that the use of theory-based proprioceptive neuromuscular stimulation for hip joint strengthening exercises positively affects patients' functional improvement in tibial fracture patients, and this may be used as a therapeutic exercise method for those with orthopedic problems in the lower extremities. One limitation of this study was that it was performed on only one tibia fracture patient, which makes it difficult to extend the treatment effects to all patients with this condition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.1
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• pp.28-36
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• 2020

In shipbuilding industry, there is conducting most of works by welding at the shipyard, and the volume of welding is increasing with international trends of green ships. Welding joint is guaranteed quality through non-destructive testing (NDT). The manual welding inspection report is produced by identifying the drawings designed, which results in losses the many workforce and occurs human errors. To solve these problems, this paper covers a system that reports on inspection information is automatically generation by input data based on shipbuilding-specific CAD. The developed system analyzes the shape data from drawings of modeling. Also, the system determines welding joints through expansion of the part boundary and generates tag numbers. In addition, it provides the function to automatically extract the information needed for inspection such as weld length, thickness and etc. We conducted test to verify the usefulness of the developed system and confirmed that the welding inspection information extracted through system matches the information shown in drawings of modeling.

• Smart Structures and Systems
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• v.29 no.1
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• pp.181-193
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• 2022

Data-driven structural health monitoring (SHM) of civil infrastructure can be used to continuously assess the state of a structure, allowing preemptive safety measures to be carried out. Long-term monitoring of large-scale civil infrastructure often involves data-collection using a network of numerous sensors of various types. Malfunctioning sensors in the network are common, which can disrupt the condition assessment and even lead to false-negative indications of damage. The overwhelming size of the data collected renders manual approaches to ensure data quality intractable. The task of detecting and classifying an anomaly in the raw data is non-trivial. We propose an approach to automate this task, improving upon the previously developed technique of image-based pre-processing on one-dimensional (1D) data by enriching the features of the neural network input data with multiple channels. In particular, feature engineering is employed to convert the measured time histories into a 3-channel image comprised of (i) the time history, (ii) the spectrogram, and (iii) the probability density function representation of the signal. To demonstrate this approach, a CNN model is designed and trained on a dataset consisting of acceleration records of sensors installed on a long-span bridge, with the goal of fault detection and classification. The effect of imbalance in anomaly patterns observed is studied to better account for unseen test cases. The proposed framework achieves high overall accuracy and recall even when tested on an unseen dataset that is much larger than the samples used for training, offering a viable solution for implementation on full-scale structures where limited labeled-training data is available.