• Wind and Structures
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• v.30 no.3
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• pp.261-273
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• 2020

This paper deals with the design, wind tunnel testing, and performance analysis of small wind turbines targeting low-power applications. Three different small-size blade designs in terms of size, shape, and twisting angle are considered and tested. We conduct wind tunnel tests while measuring the angular speed of the rotating blades, the generated voltage, and the current under varying resistive loading and air flow conditions. An electromechanical model is also used to predict the measured voltage and power and verify their consistency and repeatability. The measurements are found in qualitative agreement with those reported in previously-published experimental works. We present a novel methodology to estimate the mechanical torque applied to the wind turbine without the deployment of a torque measuring device. This method can be used to determine the power coefficient at a given air speed, which constitutes an important performance indicator of wind turbines. The wind tunnel tests revealed the capability of the developed wind turbines to deliver more than 1225 mW when subject to an air flow with a speed of 7 m/s. The power coefficient is found ranging between 26% and 32%. This demonstrates the aerodynamic capability of the designed blades to extract power from the wind.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.9
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• pp.797-804
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• 2013

In this paper, a study of a new hovering six dof underwater robot with redundant horizontal thrusters, titled HAUV (hovering AUV), is presented. The results of study on the structure design, deployment of thrusters, and development of the developed control system of the AUV was presented. For the HAUV structure, a structure design and an analysis of the thrusting system was performed. For navigation, a sensor fusion board which can proceed various sensor signals to identify correct positions and speeds was developed and a total control system including EKF (Extended Kalman Filter) was designed. Rolling, pitching and depth control tests of the HAUV have been performed, and relatively small angle error and depth tracking error results were shown.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.774-779
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• 2005

Client requirements is a concept with increasing interest in relation to several outcomes of companies, and in particular, in the event of apartment project that takes large share in the domestic construction industry, diverse angle of survey is performed to discover the client requirements and reflect them to the project to improve the quality. For this purpose, it is required to learn the client requirements and apply it in the apartment project, and the QFD (Quality Function Deployment) linked ROQ (Return On Quality) is a technique used in the manufacturing that surveys the client requirements to improve the customer satisfaction, and apply it to the quality improvement program to improve the profitability in this process. In this study, through the application of the ROQ process, the plan to improve the apartment quality management is presented. For this purpose, the consumer interview survey, FGI (focus group interview) survey and the client requirements are analyzed, and thereafter, through the interview with the specialist, the quality improvement program that enables the application to the product development of new apartment product is established. Through this process, the new apartment quality management improvement plan is presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.11
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• pp.755-762
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• 2014

In recent year, along with the rapid development of LED technology, many applications using LEDs with Visible Light Communication(VLC) have been researched. Since it is easy to provide LOS communication environment along with cheap deployment cost, the indoor positioning system based on VLC has been actively studied. In this paper, we propose an accurate indoor positioning algorithm using a stereo image sensor and white-light LEDs with the visible light communication. Indoor white-light LEDs are located at the ceiling of a room and broadcast their position information by VLC technology. Mobile receiver with stereo image sensor receives LED position information by VLC and estimates its position and angle information. Simulation results are given to show the efficiency of proposed indoor positioning algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.11
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• pp.1330-1338
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• 2011

Social activities of the elderly have been increasing as our society progresses toward an aging society. As their activities increase, so does the occurrence of falls that could lead to fractures. Falls are serious health hazards to the elderly. Therefore, development of a device that can detect fall accidents and prevent fracture is essential. In this study, we developed a portable fall detection system for the fracture prevention system of the elderly. The device is intended to detect a fall and activate a second device such as an air bag deployment system that can prevent fracture. The fall detection device contains a 3-axis acceleration sensor and two 2-axis tilt sensors. We measured acceleration and tilt angle of body during fall and activities of daily(ADL) living using the fall detection device that is attached on the subjects'. Moving mattress which is actuated by a pneumatic system was used in fall experiments and it could provide forced falls. Sensor data during fall and ADL were sent to computer and filtered with low-pass filter. The developed fall detection device was successful in detecting a fall about 0.1 second before a severe impact to occur and detecting the direction of the fall to provide enough time and information for the fracture preventive device to be activated. The fall detection device was also able to differentiate fall from ADL such as walking, sitting down, standing up, lying down, and running.

• Korean Journal of Computational Design and Engineering
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• v.19 no.4
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• pp.324-331
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• 2014

In the design of a combat vehicle, various performances such as firepower, mobility and survivability, etc., should be considered. Furthermore, since these performances relate to each other, design framework which can treat an integrated system should be employed to design the combat vehicle. In this paper, we use empirical interior ballistic and 3D combat vehicle analyses for predicting firepower and mobility performances which are developed in previous study (1) integrated performance modeling. In firepower performance, pitch and roll angle by sequential firing are considered. In mobility performance, vertical acceleration after passing through a bump is regarded. However, since there are many design variables such as mass of vehicle, mass of suspension, spring and damping coefficient of suspension and tire, geometric variables of vehicle, etc., for firepower and mobility performance, we utilize analysis of variance and quality function deployment to reduce the number of design variables. Finally, integrated design optimization is carried out for integrated performance such as firepower and mobility.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.7
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• pp.100-111
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• 2003

The HAUSAT-1(Hankuk Aviation University SATellite-1) will orbit at the altitude of 650km-800 km with 65 or 98 degree inclination angle. The effects of magnetic field and Earth gravity are more predominant than other space disturbances because the HAUSAT-1 will be positioned in LEO(Low Earth Orbit). The HAUSAT-1 design implements a magnetic control system and gravity-stable system which implement the solar panel deployment system. The simulation using MATLAB was performed to make sure the attitude stability of HAUSAT-1, which is based on the 8th order magnetic field model and non-linear equations of disturbances and the HAUSAT-1 attitude. The stability is investigated for two different HAUSAT-1 configurations and attitude which are affected by disturbances through simulation. The results for gravity-gradient stable and non gravity-gradient stable system are compared. Methodology of attitude stabilization was explored to develop an effective attitude control system for the HAUSAT-1 using magnetic torquers.

• Journal of the Korea Society for Simulation
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• v.25 no.3
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• pp.53-63
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• 2016

We consider simulation study combining static and mobile decoys for survivability of a surface warship against torpedo attack. It is assumed that an enemy torpedo is a passive acoustic homing torpedo and detects a target within its maximum target detection range and search beam angle by computing signal excess via passive sonar equation, and a warship conducts an evasive maneuvering with deploying static and mobile decoys simultaneously to counteract a torpedo attack. Suggesting the four different decoy deployment plans to achieve the best plan, we analyze an effectiveness for a warship's survival probability through Monte Carlo simulation, given a certain experimental environment. Furthermore, changing the speed and the source level of decoys, the maximum torpedo detection range of warship, and the maximum target detection range of torpedo, we observe the corresponding survival probabilities, which can provide the operational capabilities of an underwater defense system.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• v.26 no.2
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• pp.130-140
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• 2024

Objective: To assess whether local anesthetic infiltration could minimize the carotid baroreceptor reflex (CBR) which has an incidence after carotid artery stenting (CAS) that varies from 29% to 51%. Methods: This retrospective single-center study included 51 patients (mean age, 70.47 years) who underwent CAS for carotid stenosis. The groups included patients who underwent CAS for asymptomatic ischemic stroke (n=41) or symptomatic disease (n=10). Preprocedural percutaneous lidocaine injections (PPLIs) were administered to 70.6% and 5.9% of patients who underwent elective CAS and emergency CAS, respectively. Results: Among patients who received PPLIs, the mean degree of stenosis was 80.5% (95% confidence interval [CI]: ±10.74, 51-98%). The mean distance from the common carotid artery bifurcation to the most stenotic lesion (CSD) was 8.3 mm (95% CI: ±0.97, 6.3-10.2 mm); the mean angle between the internal carotid artery and common carotid artery (CCA) trunk (IAG) was 65.6° (95% CI: ±2.39, 61-70°). Among patients who did not receive PPLIs, the mean degree of stenosis was 84.0% (95% CI: ±8.96, 70-99%). The mean CSD was 5.9 mm (95% CI: ±1.83, 1.9-9.9 mm); the mean IAG was 60.4° (95% CI: ±4.41, 51-70°). The procedure time was longer in the PPLI group than in the no PPLI group (28.19 [n=39] vs. 18.88 [n=12] days) (P=0.057); the length of intensive care unit stay was shorter in the PPLI group (20.01 [n=36] vs. 28.10 [n=5] days) (P=0.132). Conclusions: Targeted PPLI administration to the carotid bulb decreased aberrant heart rates and blood pressure changes induced by carotid stent deployment and balloon inflation. As CBR sensitivity increases with decreasing distance to the stenotic lesion from the CCA bifurcation, PPLIs may help stabilize patients during procedures for stenotic lesions closer to the CCA.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.2
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• pp.127-135
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• 2022

Compared to the continuous increase of domestic nano-satellite development cases, the initial communication success rate is relatively low. In a situation where communication cases of LEO satellites using commercial satellite communication networks are increasing recently. In this situation, the SNIPE project developed by the KASI(Korea Astronomy and Space Science Institute), KARI(Korea Aerospace Research Institute), and Yonsei University apply an Iridium module for communication test to the SNIPE nano-satellites. Therefore, in this paper, the visibility analysis of the iridium module on the SNIPE satellite was analyzed under considering the orbital and communication environment of the iridium satellite constellation and the attitude control mode. In the case of LEO satellites, the communication possibility was limited due to the relatively small iridium communication coverage for high altitude and the high doppler shift considered in the iridium communication network. For this reason, in this paper, it could be simulated that there was a more performance difference according to the difference in relative RAAN(Right Ascension of Ascending Node) angle with the Iridium constellation. Finally, by checking the visibility of communication module under the tumbling situation that occurred during the initial deployment of the nano-satellite, the possibility of using the iridium communication technology was analyzed.