• Smart Media Journal
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• v.12 no.7
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• pp.59-67
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• 2023

Recently, research on behavior analysis tracking human posture and movement has been actively conducted. In particular, OpenPose, an open-source software developed by CMU in 2017, is a representative method for estimating human appearance and behavior. OpenPose can detect and estimate various body parts of a person, such as height, face, and hands in real-time, making it applicable to various fields such as smart healthcare, exercise training, security systems, and medical fields. In this paper, we propose a method for classifying four exercise movements - Squat, Walk, Wave, and Fall-down - which are most commonly performed by users in the gym, using OpenPose-based deep learning models, DNN and CNN. The training data is collected by capturing the user's movements through recorded videos and real-time camera captures. The collected dataset undergoes preprocessing using OpenPose. The preprocessed dataset is then used to train the proposed DNN and CNN models for exercise movement classification. The performance errors of the proposed models are evaluated using MSE, RMSE, and MAE. The performance evaluation results showed that the proposed DNN model outperformed the proposed CNN model.

• Journal of Biomedical Engineering Research
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• v.44 no.4
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• pp.255-263
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• 2023

Clinical ultrasound (US) is a widely used imaging modality with various clinical applications. However, capturing a large field of view often requires specialized transducers which have limitations for specific clinical scenarios. Panoramic imaging offers an alternative approach by sequentially aligning image sections acquired from freehand sweeps using a standard transducer. To reconstruct a 3D volume from these 2D sections, an external device can be employed to track the transducer's motion accurately. However, the presence of optical or electrical interferences in a clinical setting often leads to incorrect measurements from such sensors. In this paper, we propose a deep learning (DL) framework that enables the prediction of scan trajectories using only US data, eliminating the need for an external tracking device. Our approach incorporates diverse data types, including correlation volume, optical flow, B-mode images, and rawer data (IQ data). We develop a DL network capable of effectively handling these data types and introduce an attention technique to emphasize crucial local areas for precise trajectory prediction. Through extensive experimentation, we demonstrate the superiority of our proposed method over other DL-based approaches in terms of long trajectory prediction performance. Our findings highlight the potential of employing DL techniques for trajectory estimation in clinical ultrasound, offering a promising alternative for panoramic imaging.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.92-92
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• 2021

체외수정을 기반으로 이루어지는 성게의 수정 과정은 성게 주변에서 형성되는 복잡한 난류 흐름의 영향을 받게 된다. 성게 몸체의 하류부에 형성되는 재순환 영역 (recirculation zone) 내에는 다양한 난류 와류 흐름이 존재하며, 이들은 성게 몸체에서 방출된 정자와 난자의 충돌을 일으키고 수정 과정에 지대한 영향을 미친다. 즉, 성게의 수정 과정을 이해하기 위해서는 성게 주변의 흐름에 대한 유체역학적 관점에서의 분석이 수행되어야 한다. 본 연구의 목적은 성게 몸체에 의해 발생한 난류 흐름이 성게의 체외 수정에 미치는 영향에 대해 조사하는 것이다. 이를 위해 본 연구에서는 상용 프로그램인 오픈폼 (OpenFaom)을 활용하여 수치 모의를 수행하였다. 성게 주변의 유동장은 LES (Large Eddy Simulation)을 기반으로 모의하였고, 정자와 난자의 확산 궤적은 라그랑지안 입자 추적 (Lagrangian Particle Tracking) 알고리즘을 통해 구현하였다. 총 5개의 유속 조건 (0.025 - 0.20 m/s) 에 대해 모의를 수행하였으며 정자와 난자 사이의 거리를 바탕으로 수정률을 산정하였다. 정자와 난자의 뭉쳐있거나 퍼져있는 공간적인 분포 형태는 Standardized Morisita 지수를 통해 수치적으로 표현하였으며 이들과 수정률과의 관계를 규명하였다. 연구 결과에 따르면 성게 수정은 유속 조건이 0.1 m/s일 때 가장 빈번하게 발생하였으며, 성게 수정의 성공 여부는 크게 2가지 조건에 의해 결정되었다. 첫 번째로, Standardized Morisita 지수가 높을수록 다시 말해 생식세포들이 공간적으로 뭉쳐있어야 하며 두 번째는, 생식세포들을 충돌시킬 수 있는 원동력인 작은 와류가 존재해야 한다. 와류의 크기가 너무 크게 되면 생식세포들은 충돌하지 않고 확산만 되기 때문에 오히려 수정률이 감소하였다. 영역별로 분석한 결과에 따르면, 성게 몸체에 의해 형성된 재순환 영역이 수정과정에 있어 가장 지배적인 영역임을 확인하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.95-95
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• 2022

남극에 상주하는 여러 과학기지 근처 해역에서 5 mm 이하의 크기를 가지는 미세플라스틱이 다량 발견되고 있으며, 그에 따라 과학기지에서 방출하는 방류수가 미세플라스틱의 지역 소스로 여겨지고 있다. 현재는 미세플라스틱의 오염 수준을 이해하는 정도에서 그쳤으며, 미세플라스틱의 물리적인 운송 메커니즘을 이해하고자 하는 시도는 상대적으로 부족한 실정이다. 남극 세종과학기지 근처에서도 미세플라스틱이 발견됨에 따라 본 연구에서는 과학기지 인근인 마리안 소만(Marian Cove)에서의 미세플라스틱 운송 메커니즘을 확인하고자 한다. 연구 대상 지역에서 미세플라스틱의 체류 시간은 짧기 때문에, 미세플라스틱에 생물오손 또는 풍화작용이 일어나기에는 충분하지 않은 시간이다. 따라서, 마리안 소만에서 발견된 미세플라스틱에 대해 연직 속도에 따라 확실히 가라앉는 그룹과 확실히 떠오르는 그룹으로 나누어 입자의 이송 메커니즘을 파악하였다. 해수 유동 모델과 파랑 모델을 결합하여 마리안 소만의 해수 흐름을 재현하였으며, 과학기지 방류 구 위치에서 방출된 미세플라스틱의 이송 경로는 라그랑지안 입자 추적(Lagrangian Particle Tracking) 방법을 이용하였다. 본 연구에서는 미세플라스틱의 궤적을 설명하기 위해 입자의 이송에 영향을 주는 힘을 결정할 수 있는 무차원 수 HK angle을 제안하였으며, 이를 이용하여 마리안 소만에서의 미세플라스틱 이송을 설명하였다. 대상 해역 내에서 확실히 떠오르는 그룹은 표층 흐름을 따라 해안선에 도달하였으며, 확실히 가라앉는 그룹은 방출 직후 빠르게 가라 앉으며 방출 위치 근처인 해저에 집적되었다. HK angle에 따르면, 마리안 소만의 연직 흐름이 강할 경우에는 미세플라스틱의 특성에 관계없이 해수 흐름을 따라 이송됨을 확인하였다. 더 나아가, 조석에 따라 미세플라스틱의 방출 시간을 달리하고, 방출 위치를 달리하여 모의함으로써 마리안 소만과 같이 작은 만에서 미세플라스틱 오염도를 줄이기 위한 적절한 방류수 방출 시간 및 위치를 제안하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.281-281
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• 2022

바닥에서 생성되는 난류는 순간적으로 강한 모멘텀을 바닥에 전달함과 동시에 바닥에 있는 입자를 움직이게 한다. 경계층 내 난류 운동에 대한 분석은 다양한 유사 이송 문제를 이해하기 위해 필수적이며 이에 따라 많은 선행 연구들은 실험실 실험을 통해 해당 연구를 수행하였다. 본 연구에서는 선행 연구에서 사용하지 못했던 진보된 실험 방법을 활용하여 바닥 경계층 내의 난류 운동에 대해 확인하고 해당 운동에 의해 관성 입자의 움직임이 어떻게 발생하는지에 대하여 물리적으로 설명하고자 한다. 다양한 흐름 조건에서 3가지의 입경 크기를 가지는 모래 입자를 가지고 실험을 수행하였으며, 실험 조건별 고해상도 유속장 및 관성 입자의 움직임은 3차원 입자 영상 유속계 (Particle Image Velocimetry; 이하 PIV)와 입자 추적 유속계 (Particle Tracking Velocimetry; 이하 PTV)를 동시에 적용하여 파악하였다. 취득된 3차원 유속장과 입자 궤적을 기반으로 실험 조건별 흐름 및 입자 거동 특성에 대해 분석하였으며, 관성 입자의 움직임을 발생시키는 3차원 난류 운동은 측정된 유속장에서 산정한 Q-criterion 값을 기반으로 도식화하였다. 측정값 내에는 난류 운동에 대한 정보와 더불어 잡음이 포함되어 있으므로 이를 제거하고자 적합 직교 분해 (Proper Orthogonal Decomposition; 이하 POD) 방법을 적용하였다. 그리고 POD로 추출한 유속장을 통해 바닥면 부근에 존재하는 헤어핀 와류 운동 혹은 와류 묶음과 같은 난류 고유 구조를 파악하였다. 해당 와류 운동들의 3차원 난류 특성을 확인하고자 비등방성 불변 지도(anisotropy invariant map)를 활용하였으며 경계층 내부에서 난류의 형태가 흐름 방향으로 늘어진 럭비공 형태임을 확인하였다. 마지막으로, 입자의 움직임을 발생시키는 난류 이벤트를 결정하고자 사방구 분석 (Quadrant analysis) 기법을 적용하였으며 흐름 조건별로 입자를 움직이게 하는 난류 이벤트는 달라짐을 확인하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.63-70
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• 2023

In this paper, we propose a Mixed Reality based rehabilitation exercise solution with the goal of mitigating one of the most common chronic conditions among the elderly, musculoskeletal disorders. In modern society, as the number of elderly increases, more people engage in office work and engage in more sedentary activities. Due to repetitive work in the office, muscle strength decreases and this causes many difficulties in daily life. In this study, we developed a mixed reality based exercise platform to solve these chronic musculoskeletal diseases. VR is not appropriate for elderly because of dizziness. In addition, we developed a wearable sensor based on IMU and attached it to important parts of the upper body to motion tracking. We developed a algorithm synchronize to raw data from wearable sensor with in a vr avatar. Ederly can check in real time whether rehabilitation exercises are being performed accurately through the avatar.

• Smart Structures and Systems
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• v.33 no.4
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• pp.291-300
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• 2024

Uncertainty of the model, system delay and drive dynamics can be considered as normal uncertainties, and the main source of uncertainty in the seismic control system is related to the nature of the simulated seismic error. In this case, optimizing the management strategy for one particular seismic record will not yield the best results for another. In this article, we propose a framework for online management of active structural management systems with seismic uncertainty. For this purpose, the concept of reinforcement learning is used for online optimization of active crowd management software. The controller consists of a differential controller, an unplanned gain ratio, the gain of which is enhanced using an online reinforcement learning algorithm. In addition, the proposed controller includes a dynamic status forecaster to solve the delay problem. To evaluate the performance of the proposed controllers, thousands of ground motion data sets were processed and grouped according to their spectrum using fuzzy clustering techniques with spatial hazard estimation. Finally, the controller is implemented in a laboratory scale configuration and its operation is simulated on a vibration table using cluster location and some actual seismic data. The test results show that the proposed controller effectively withstands strong seismic interference with delay. The goals of this paper are towards access to adequate, safe and affordable housing and basic services, promotion of inclusive and sustainable urbanization and participation, implementation of sustainable and disaster-resilient buildings, sustainable human settlement planning and manage. Simulation results is believed to achieved in the near future by the ongoing development of AI and control theory.

• The Journal of Korean Society for Radiation Therapy
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• v.17 no.2
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• pp.125-131
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• 2005

Purpose : For stereotactic radiosurgery (SRS) of a tumor in the region whose movement due to respiration is significant, like Lung lower lobe, the gated therapy, which delivers radiation dose to the selected respiratory phases when tumor motion is small, was performed using the Respiratory gating system and its clinical effectiveness was evaluated. Materials and Methods : For two SRS patients with a tumor in Lung lower lobe, a marker block (infrared reflector) was attached on the abdomen. While patient' respiratory cycle was monitored with Real-time Position Management (RPM, Varian, USA), 4D CT was performed (10 phases per a cycle). Phases in which tumor motion did not change rapidly were decided as treatment phases. The treatment volume was contoured on the CT images for selected treatment phases using maximum intensity projection (MIP) method. In order to verify setup reproducibility and positional variation, 4D CT was repeated. Results : Gross tumor volume (GTV) showed maximum movement in superior-inferior direction. For patient #1, motion of GTV was reduced to 2.6 mm in treatment phases ($30{\sim}60%$), while that was 9.4 mm in full phases ($0{\sim}90%$) and for patient #2, it was reduced to 2.3 mm in treatment phases ($30{\sim}70%$), while it was 11.7 mm in full phases ($0{\sim}90%$). When comparing two sets of CT images, setup errors in all the directions were within 3 mm. Conclusion : Since tumor motion was reduced less than 5 mm, the Respiratory gating system for SRS of Lung lower lobe is useful.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.1
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• pp.27-40
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• 2013

This study is about development of technology system for an advanced deep-sea unmanned underwater robot of S. Korea analysed by the application of scenario planning. It was developed a 6000m class next-generation deep-sea unmanned underwater vehicle(or robot, UUV) system, soonly ROV 'Hemire' and Depressor 'Henuvy' in 2006 at S. Korea and motion control, adaptive control algolithm, a work-space manipulator control algolithm, especially the underwater inertial-acoustic navigation system robust to initial errors and sensor failures. But there are remained matters on position tracking of the USBL, inertial-acoustic navigation system, attitude sensor, designed sonar sensors. So this study suggest the new idea for settle the matters and then this idea help the development of the underwater inertial-acoustic navigation system robust to initial errors and sensor failures, such as acoustic signal drop-out, by modifying the error covariance of the failed sonar signal when drop-out occurs. As a result, the future policy for deep-sea unmanned underwater robot of S. Korea is to further spur the development of new technology and more improvement of the technology level for deep-sea unmanned underwater robot system with indicator and imaginary wall as external device.

• Journal of Biomedical Engineering Research
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• v.21 no.6
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• pp.615-621
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• 2000

A social phobia is an anxiety disorder characterized by extreme fear and phobic avoidance of social and performance situations. Medications or cognitive-behavior methods have been mainly used in treating it. These methods have some shortcomings such as being inefficient and difficult to apply to treatment. Lately the virtual rcality technology has been applied to dcal with the anxiety disorders in order to compcnsate for these defects. A virtual environment provides a patient with stimuli which cvokes a phobia. and the patient's exposure to the virtual phobic situation make him be able to overcome it. In this study, we suggested the public speaking simulator based on a personal computer for the treatment of social phobia. The public speaking simulator was composed of a position sensor. head mount display and audio system. And a virtual environment for the treatment was suggested to be a seminar room where 8 avatars are sitting. The virtual environment includes a tracking system the trace a participant's head-movement using a HMD with position sensor and 3D sound is added to the virtual environment so that he might fcel it realistic. We also made avatars' motion and facial expression change in reaction to a participant's speech. The goal of developing public speaking simulator is to apply to treat fear of public speaking efficiently and economically. In a future study. we should get more information about immergence and treatment efficiency by clinical test and apply it to this simulator.