• IEIE Transactions on Smart Processing and Computing
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• 제4권6호
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• pp.443-449
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• 2015

This paper considers the physical layer security problem for a two-way vehicle-to-vehicle network, where the two source vehicles can only exchange information through an untrusted relay vehicle. The relay vehicle helps the two-way transmission but also acts as a potential eavesdropper. Each vehicle has a random velocity. By exploiting the random carrier frequency offsets (CFOs) caused by random motions, a secure double-differential two-way relay scheme is proposed. While achieving successful two-way transmission for the source vehicles, the proposed scheme guarantees a high decoding error floor at the untrusted relay vehicle. Average symbol error rate (SER) performance for the source vehicles and the untrusted relay vehicle is analyzed. Simulation results are provided to verify the proposed scheme.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2011년도 추계학술대회
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• pp.769-772
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• 2011

본 연구는 연마와 분진을 한꺼번에 해결하고자 로봇형 진공식 표면연마 머신(Robotic Vacuum Sweeping Machine)을 개발을 통하여 금속표면의 연마작업을 수행할 때 금속표면으로부터 탈피되는 각 종이물질과 연마휠의 회전으로 발생되는 분진을 진공방식으로 집진하게 되고, 항상 작업자가 머신의 이동방향을 주시해야하는 불편함을 센서(카메라, 레이저스캐너 등)를 부착하여 작업환경인식과 작업진행시 발생할 수 있는 돌발적 위험상황에 대처하기 위한 장애물 판단이 가능한 구조를 가진 진공식 표면 연마기를 소개하도록 한다.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.525-543
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• 2010

Testing and validation processes are critical tasks in developing a new hardware platform based on a new technology. This paper describes a series of experiments to evaluate the performance of a newly developed MEMS-based wireless sensor node as part of a wireless sensor network (WSN). The sensor node consists of a sensor board with four accelerometers, a thermometer and filtering and digitization units, and a MICAz mote for control, local computation and communication. The experiments include calibration and linearity tests for all sensor channels on the sensor boards, dynamic range tests to evaluate their performance when subjected to varying excitation, noise characteristic tests to quantify the noise floor of the sensor board, and temperature tests to study the behavior of the sensors under changing temperature profiles. The paper also describes a large-scale deployment of the WSN on a long-span suspension bridge, which lasted over three months and continuously collected ambient vibration and temperature data on the bridge. Statistical modal properties of a bridge tower are presented and compared with similar estimates from a previous deployment of sensors on the bridge and finite element models.

• Smart Structures and Systems
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• 제13권2호
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• pp.235-255
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• 2014

This paper mainly introduces recently developed technologies pertaining to the design and implementation of Active Mass Damper (AMD) control system on a high-rise building subjected to wind load. Discussions include introduction of real structure and the control system, the establishment of analytical model, the design and optimization of a variety of controllers, the design of time-varying variable gain feedback control strategy for limiting auxiliary mass stroke, and the design and optimization of AMD control devices. The results presented in this paper demonstrate that the proposed AMD control systems can resolve the issues pertaining to insufficient floor stiffness of the building. The control system operates well and has a good sensitivity.

• Smart Structures and Systems
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• 제23권2호
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• pp.185-194
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• 2019

The probabilistic tsunami risk assessment of large coastal areas is challenging because the inland propagation of a tsunami wave requires an accurate numerical model that takes into account the interaction between the ground, the infrastructures, and the wave itself. Classic mesh-based methods face many challenges in the propagation of a tsunami wave inland due to their ever-moving boundary conditions. In alternative, mesh-less based methods can be used, but they require too much computational power in the far-field. This study proposes a hybrid approach. A mesh-based method propagates the tsunami wave from the far-field to the near-field, where the influence of the sea floor is negligible, and a mesh-less based method, smooth particle hydrodynamic, propagates the wave onto the coast and inland, and takes into account the wave structure interaction. Nowadays, this can be done because the advent of general purpose GPUs made mesh-less methods computationally affordable. The method is used to simulate the inland propagation of the 2004 Indian Ocean tsunami off the coast of Indonesia.

• 한국컴퓨터정보학회논문지
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• 제24권1호
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• pp.159-166
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• 2019

Recently, the advanced development of smart devices has increased the interest in health-care, and many people are paying more attentions to disease prevention than disease treatment. Among these prevention methods, the bare body movement has received much attention, and especially walking exercise is attracting much attention because it is enjoyable without any restrictions on place and time. Walking exercise is generally divided into two types: walking on the ground and climbing the stairs. Walking up the stairs consumes much more calories compared to walking on the ground. These walking exercises have the advantage that they can be easily performed by male and female without special equipments or economic considerations. However, there is a lack of applications and systems that accurately determine such walking and stair walking and measure momentum according to stair walking. In this paper, we designed and implemented a real-time walking status analysis system using smartwatch's, pedometer, smartphone's barometer and beacons.

• Smart Structures and Systems
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• 제29권4호
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• pp.549-560
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• 2022

The optimum damping and tuning frequency ratio of the tuned mass damper-inerter (TMDI) for the base-isolated structure is obtained using the numerical searching technique under stationary white-noise and filtered white-noise earthquake excitation. The minimization of the isolated structure's mean-square relative displacement and absolute acceleration, as well as the maximization of the energy dissipation index, were chosen as the criteria for optimality. Using a curve-fitting technique, explicit formulae for TMDI damping and tuning frequency for white-noise excitation are then derived. The proposed empirical expressions for TMDI parameters are found to have a negligible error, making them useful for the effective design of base-isolated structures. The effectiveness of TMDI and its optimum parameters are influenced by the soil condition and isolation frequency, according to the comparison made of the optimized parameters and response with different soil profiles. The effectiveness of an optimally designed TMDI in controlling the displacement and acceleration response of the flexible isolated structure under real and pulse-type earthquakes is also observed and found to be increased as the inertance mass ratio increases.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.214-215
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• 2020

The 3D scanning technology is being introduced for quality inspection of building construction. Therefore, this study tried to confirm whether it is possible to check the quality of rebar by using 3D scanning. After rebar placed on the formwork slab was scanned with a 3D scanner, the rebar spacing was confirmed by overlapping with the CAD drawing. As a result, the 3D scanner was able to check the quality of rebar work on one floor at a time. Therefore, 3D scanning could be used for quality inspection of rebar works such as columns, beam and girders, walls, and slabs in the future.

• 한국전문물리치료학회지
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• 제27권4호
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• pp.257-263
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• 2020

Background: The hip muscle plays various roles. Several types of functional performance tests are used for the assessment of patients with various lower extremity injuries. Hip muscle functions are important to test the performance of maintaining the spine, pelvic, and leg during bridging exercise. We designed a novel functional performance test tool, which we named close kinetic chain dynamic lower extremity stability (CKCLE) test to assess hip muscle functions. Objects: The purpose of this study was to determine the relationship between CKCLE test and hip extensor, external rotator, and abductor strengths. Methods: Twenty-two subjects were recruited in the present study (13 males and 9 females). The hip extensor, external rotator, and abductor muscle strengths were measured using a Smart KEMA strength sensor. When the examiner said "Go", the subject performed the CKCLE test by moving one leg from the floor and touching the opposite knee and then return to the floor while maintaining the bridging position. The subjects attempted as many "touches" as possible in the allotted time (20 seconds) during the maximal tests. The correlation between the hip muscle (extensor, external rotator, and abductor) strength of the supporting leg and the number of CKCLE tests performed in 20 seconds was determined using the Pearson correlation. Results: Hip extensor (r = 0.626, p < 0.05), hip external rotator (r = 0.616, p < 0.05), and hip abductor muscle strengths (r = 0.475, p < 0.05) positively correlated with the number of CKCLE tests performed. Conclusion: We designed a CKCLE test and found that performance in the test correlated with hip extensor, external rotator, and abductor muscle strengths. The result suggests that the CKCLE test can be applied as a performance test to assess the functions of the hip extensor, external rotator, and hip abductor muscles.

• 한국인터넷방송통신학회논문지
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• 제12권6호
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• pp.199-206
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• 2012

본 논문에서는 스마트폰의 자이로센서를 이용하여 다양한 각도에서 촬영한 현실세계의 객체를 증강현실을 위한 자연 마커로 사용할 수 있도록 가상의 Frontal-View로 변환할 수 있는 알고리즘을 설계하고 구현하였다. 제안한 알고리즘은 pitch, roll, yaw 3축에 대한 회전행렬을 획득하여 대상 이미지에 대한 yaw의 기준점을 설정하였다. 그 후 대상 이미지가 바닥, 벽면, 천장 중 어느 면인지 판단하여 그에 대한 회전 행렬을 보정하였다. 마지막으로 자이로 센서 좌표계와 영상 좌표계 사이의 차이를 고려해 Frontal-View를 얻기 위한 호모그래피 행렬을 획득하여 투영변환을 통해 촬영 영상으로부터 Frontal-View를 획득할 수 있도록 설계하였다. 구현된 Frontal-View 변환 프로그램을 평가하기 위해 바닥, 벽면, 천장에 대해 주변 환경을 스마트폰 환경에서 촬영한 영상을 Frontal-View로 변환하도록 테스트를 한 결과 본 논문에서 설계 및 구현한 변환 알고리즘이 여러 각도에서 촬영한 영상을 정상적으로 Frontal-View로 변환하는 것을 확인하였다.