• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.696-699
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• 2018

This paper introduces a system that enables pupillary tracing and communication with patients with amyotrophic lateral sclerosis (ALS) who can not move free. Face and pupil are tracked using OpenCV, and eye movements are detected using DE1-SoC board. We use the webcam, track the pupil, identify the pupil's movement according to the pupil coordinate value, and select the character according to the user's intention. We propose a system that can use relatively low development cost and FPGA can be reusable, and can select a text easily to mobile phone by using Bluetooth.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.2
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• pp.117-126
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• 2016

In this paper, a numerical procedure for the natural vibration analysis of plates with openings and carlings based on the assumed mode method is extended to assess their forced response. Firstly, natural response of plates with openings and carlings is calculated from the eigenvalue equation derived by using Lagrange's equation of motion. Secondly, the mode superposition method is applied to determine frequency response. Mindlin theory is adopted for plate modelling and the effect of openings is taken into account by subtracting their potential and kinetic energies from the corresponding plate energies. Natural and frequency response of plates with openings and carlings subjected to point excitation force and enforced acceleration at boundaries, respectively, is analysed by using developed in-house code. For the validation of the developed method and the code, extensive numerical results, related to plates with different opening shape, carlings and boundary conditions, are compared with numerical data from the relevant literature and with finite element solutions obtained by general finite element tool.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.26-28
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• 2006

When materials such as metal are into the secondary side of steam generator, they, so called foreign objects, may have influences on the integrity of the steam generator tubes. They cause the tube wear due to the relative motion between the tubes and foreign objects and the tube impact due to flow. The best way to avoid the effects is to remove all the foreign objects. However, it is not easy to remove the foreign materials thoroughly due to their condition such as the location. Considering the wear and impact by the foreign materials, KEPRI(Korea Electric Power Research Institute) developed the methodology to evaluate the foreign materials analytically. This methodology was described with a computer program in order to obtain the fast results. The program informs whether the tubes have the structural integrity when the foreign material strikes the tubes. Moreover, this gives us the remaining life of the steam generator tubes. In this paper, the program, which evaluates the effects of the foreign objects in the secondary side of steam generator, is introduced.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.833-841
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• 2014

This paper proposes an algorithm to estimate the wind velocity by tracking free flying balloons. Balloons used in this method are expendable but inexpensive, which increases the usefulness of the method. Also we can obtain accurate 3D information by using multiple cameras and estimate the wind velocity of the local field. The proposed system consists of aerodynamic modeling of the balloon, a tracking algorithm using image processing, and the velocity estimation algorithm. We performed unit tests of each algorithm for the verification. The method is validated using a system simulation and sources of error case identified.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.11
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• pp.1022-1032
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• 2000

We propose a sliding mode controller tracking the states of a time-varying reference model. The reference model generates the desired trajectories of the states, and the sliding mode controller regulates robustly the errors between the desired states and the measured states. We apply this controller to the overhead crane. Its reference model generates the trajectories of the damped-out swing angle and the swing angular velocity to suppress the swinging motion caused by the acceleration and the deceleration of crane transportation. Also, this model generates the desired trajectories of the position and velocity of the crane. The crane model is identified from the experimental data using an orthogonal function. Kalman filtering is applied to estimate the crane states. The designed controller is simulated on a computer and is tested through a 2-ton industrial overhead crane using the vector-controlled servo motor system. It is verified that, from the simulated and experimental results, the sliding mode controller tracking a time-varying reference model works well.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.305-316
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• 2007

Free field ground motion during earthquake is significantly affected by the local soil conditions and it is essential for the seismic design to perform the site specific ground response analysis. So, Round Robin Test (RRT) on ground response analysis was performed for three sites in Korea. A total of 12 teams presented the results of ground response analysis with used input soil properties based on own judgement. In this paper, the results of one dimensional equivalent linear analysis presented by 11 teams were compared to evaluate the effect of input soil properties on ground response analysis. Additionally, 4 influence factors on ground response analysis, that is shear wave velocity of soil layer, nonlinear dynamic deformational characteristics, bedrock depth and bedrock velocity were studied for assumed simple soil conditions.

• Journal of The Korean Association For Science Education
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• v.16 no.2
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• pp.164-174
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• 1996

본연구는 자유낙하 운동에 대학 학생의 개념을 이 개념의 역사적 변천 과정과 비교하여 분석하였다. 네 연령층(ll세,13세, 15세, 17세)으로부터 총 737명이 설문조사에 참여하였으며,설문에서 주어전 문항들은 자유낙하 운동과 관련하여 과거의 과학자(예를 들어, 아리스토텔레스, 임페루스 이론가, 갈릴레오)들이 고민하였던 핵심 문제를 반영하는 것이었다. 설문에는 세 문항이 포함되었으며,각 문항은 자유낙하 운동에 관한 세 가지 측면(즉,운동의 원인,낙하높이와 낙하속력의 관계,낙하 체의 무게와 낙하속력의 관계)에 각각 관련된 것이었다. 낙하운동의 원인에 대혜서, 전체 학생의 4.3%, 25.5%. 62.7%가 아리스토텔레스,임페루스스,갈릴레오적 관점을 각각 지닌 것으로 나타났다. 낙하높이와 낙하속력의 관계에 대혜서는,20.0% 와 29.0%의 학생들이 각각 아리스토텔레스와 갈릴레오적 관점을 지닌 것으로 냐타났다. 그리고 낙하체와 무게와 낙하속력의 관계에 대혜서는,19.0%,34.8%,42.2%의 학생들이 아리스토텔레스,임페루스,갈리레오적 관점을 지닌 것으로 나타났다. 개별 문항에서 부분적으로 임페루스적 관점으로부터 갈릴레오적 관점으로의 변화가 나타났으나,전체적으로 연령이 증가함에 따라 학생의 개념이 현대적 관점으로 변화한다고 판단 하기는 어려웠다. 그리고 본 연구로부터 학생의 개념과 그 개념의 역사적 변천 과정에 사이에 상당한 유사성과 함께 차이점이 존제함을 알 수 있었다.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.97.2-97.2
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• 2014

In this paper, we study the stability and dynamics of a magnetic field producing the M6.6 class solar flare taking place in NOAA active region (AR) 11158 on 2011 February 13th. Toriumi et. al. (2013) recently suggest that a fine scale magnetic structure on the photosphere gives a major possibility to produce the M6.6 class flare. On the other hand, they don't discuss the torus instability as a plausible mechanism even though Zhao et. al. (2014) and Janvier et. al. (2014) suspect it as the trigger mechanism of X2.2 class flare taking place later in the same AR. We are the first to investigate the stability of a nonlinear force-free field (NLFFF) prior to the M6.6 class flare against the torus instability by using analytical and numerical approaches. Consequently, we found that our NLFFF is quite stable against small perturbation. This result supports that the flare is triggered by the photospheric motion suggested by Toriumi et. al. (2013). We further perform another MHD simulation with an anomalous resistivity using the NLFFF as an initial condition. As a result, we found the eruption of strongly twisted lines. We compare our simulation results with observations and discuss relevant dynamics in detail.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1203-1207
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• 2008

For a large sized, ultra definition (UD) and high refresh rate for motion blur free AMLCD TVs, amorphous IGZO thin film transistor (TFT) are applied and investigated in terms of threshold voltage ($V_{th}$) shift influenced by active layer thickness uniformity, source drain etching technology, heat treatment and passivation condition. Optimizing above parameters, we fabricated the world's largest 15 inch XGA AMLCD successfully.

• Journal of Navigation and Port Research
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• v.44 no.2
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• pp.98-109
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• 2020

In recent years, there have been concerted efforts toward predicting ship maneuvering in shallow water since the majority of ship's accidents near harbors commonly occur in shallow and restricted waters. Enhancement of ship maneuverability at the design stage is crucial in ensuring that a ship navigates safely. However, though challenging, establishing the mathematical model of ship maneuvering motion is recognized as crucial toward accurately predicting the assessment of maneuverability. This paper focused on a study on sensitivity analysis of the hydrodynamic coefficients on the maneuverability prediction of KVLCC2 in shallow waters. Hydrodynamic coefficients at different water depths were estimated from the experimental results conducted in the square tank at Changwon National University (CWNU). The simulation of standard maneuvering of KVLLC2 in shallow waters was compared with the results of the Free Running Model Test (FRMT) in shallow waters from other institutes. Additionally the sensitivity analysis of all hydrodynamic coefficients was conducted by deviating each hydrodynamic derivative from the experimental results. The standard maneuvering parameters including turning tests and zig-zag maneuvers were conducted at different water depths and their effects on the standard maneuvering parameters were assessed to understand the importance of different derivatives in ship maneuvering in shallow waters.