• The Journal of Korea Robotics Society
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• v.11 no.2
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• pp.51-59
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• 2016

In this paper we present (1) analysis of imaging sonar measurement for two-view relative pose estimation of an autonomous vehicle and (2) bundle adjustment and 3D reconstruction method using imaging sonar. Sonar has been a popular sensor for underwater application due to its robustness to water turbidity and visibility in water medium. While vision based motion estimation has been applied to many ground vehicles for motion estimation and 3D reconstruction, imaging sonar addresses challenges in relative sensor frame motion. We focus on the fact that the sonar measurement inherently poses ambiguity in its measurement. This paper illustrates the source of the ambiguity in sonar measurements and summarizes assumptions for sonar based robot navigation. For validation, we synthetically generated underwater seafloor with varying complexity to analyze the error in the motion estimation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.276-281
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• 2014

In this research, we describe a force feedback control for industrial robots has been proposed as a system which is suitable to work utilizing pressure sensitive alternative to human. Conventionally, polished surface of the workpiece are recognized, chamfer ridge, machining processes such as deburring, and it is most difficult to automate because of its complexity, has been largely dependent on the human. To aim to build automatic vacuum system robotic force control was gripping the grinding tool, the present study we examined the adaptability to the polishing process to understand the characteristics of the control system feedback signal obtained from the force sensor mainly. Furthermore, as a field, which holds the key to the commercialization, I went ahead with the application to robotic sweeping machine. As a result, the final sweeping utilizing a robot machine to obtain a very good grinded surface was revealed.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.271-273
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• 2010

태양광발전시스템에서 PV모듈이나 어레이의 성능특성 및 성능추정이 요구되고 있다. 태양광 발전 모듈은 장기간 사용 시 환경 요인 등으로 효율이 나빠지며 어레이의 특정 모듈 효율저하는 전체 발전 전력의 감소를 초래하므로 실시간 감시가 필요하다. 이 논문은 태양광 발전 모듈의 발전 전력을 실시간으로 측정하기 위한 것이다. 모듈의 출력을 실시간으로 측정하기 위해 전압, 전류 측정 회로를 제작하고 온도, 일조량 측정 장치를 제작하여 RS485 통신으로 연결하였다. Visual Studio - Basic .Net(2005)과 NI사의 Measurement Studio를 이용하여 실시간 모니터링 프로그램을 제작하였고, 모듈들 사이의 상대적인 발전 출력을 비교하여 효율 저하가 의심되는 모듈을 실시간으로 탐색하였다. 20개 모듈의 직병렬로 구성된 1kW 태양광 발전체에 적용하여 시험한 결과 2개의 모듈에서 성능 저하가 의심되는 결과가 확인되었다.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.5
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• pp.573-579
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• 2021

In this study, flow analysis was performed on three types of strainers for ships with different flow rates to predict the pressure drop of the strainer due to the filter of strainer. In the case of flow analysis, the flow analysis was performed by applying the porous media method by applying the resistance value derived by Ergun's equation to the filter position. As a result of the analysis, it was found that when the dimensions of the strainer body were small, the influence of the flow rate on the pressure drop was large. In addition, the amount of pressure drop and the flow rate are almost linearly proportional, and an analysis formula that can predict the amount of pressure drop was derived. In order to predict the amount of pressure drop of the strainer when blockage exist in the strainer filter, the analysis was performed by introducing the resistance ratio to derive the prediction equation. Using this equation, it is thought that it will be possible to predict the performance of the strainer due to blockage in the future strainer design and field application.

• The Journal of Korea Robotics Society
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• v.16 no.2
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• pp.94-102
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• 2021

This study addresses a method for 3D reconstruction using acoustic data with heterogeneous sonar devices: Forward-Looking Multibeam Sonar (FLMS) and Profiling Sonar (PS). The challenges in sonar image processing are perceptual ambiguity, the loss of elevation information, and low signal to noise ratio, which are caused by the ranging and intensity-based image generation mechanism of sonars. The conventional approaches utilize additional constraints such as Lambertian reflection and redundant data at various positions, but they are vulnerable to environmental conditions. Our approach is to use two sonars that have a complementary data type. Typically, the sonars provide reliable information in the horizontal but, the loss of elevation information degrades the quality of data in the vertical. To overcome the characteristic of sonar devices, we adopt the crossed installation in such a way that the PS is laid down on its side and mounted on the top of FLMS. From the installation, FLMS scans horizontal information and PS obtains a vertical profile of the front area of AUV. For the fusion of the two sonar data, we propose the probabilistic approach. A likelihood map using geometric constraints between two sonar devices is built and a monte-carlo experiment using a derived model is conducted to extract 3D points. To verify the proposed method, we conducted a simulation and field test. As a result, a consistent seabed map was obtained. This method can be utilized for 3D seabed mapping with an AUV.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.135-138
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• 2009

G-Sensor is being used for controlling motion of smart-phone and robot. G-Sensor can control motion to several direction, because it is composed of X, Y, and Z axis and also can be used on many mobile-phone by using Wi-Fi communication and RS-232C communication on the Bluetooth module. In this research, we suggest the application that realize and develop visual-vehicle-remote-control-system by using mobile-phone with G-Sensor so that drivers can more easily remote control and manage their vehicle with mobile-phone in real-time visual.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1424-1430
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• 2020

In this paper, we propose an algorithm to remove AWGN by considering the characteristics of noise present in the image. The proposed algorithm uses block matching to calculate the output, and calculates an estimate by determining the similarity between the center mask and the matching mask. The output of the filter is calculated by adding or subtracting the estimated value and the input pixel value, and weighting is given according to the standard deviation of the center mask and the noise constant to obtain the final output. In order to evaluate the proposed algorithm, the simulation was performed in comparison with the existing methods, and analyzed through the enlarged image and PSNR comparison. The proposed algorithm minimizes the effect of noise, preserves important characteristics of the image, and shows the performance of removing noise efficiently.

• Journal of Powder Materials
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• v.28 no.6
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• pp.509-517
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• 2021

Smart materials capable of changing their characteristics in response to stimuli such as light, heat, pH, and electric and magnetic fields are promising for application to flexible electronics, soft robotics, and biomedicine. Compared with conventional rigid materials, these materials are typically composed of soft materials that improve the biocompatibility and allow for large and dynamic deformations in response to external environmental stimuli. Among them, smart magnetic materials are attracting immense attention owing to their fast response, remote actuation, and wide penetration range under various conditions. In this review, we report the material design and fabrication of smart magnetic materials. Furthermore, we focus on recent advances in their typical applications, namely, soft magnetic actuators, sensors for self-assembly, object manipulation, shape transformation, multimodal robot actuation, and tactile sensing.

• Journal of IKEEE
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• v.25 no.4
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• pp.644-649
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• 2021

Self-Imitation Learning is a simple off-policy actor-critic algorithm that makes an agent find an optimal policy by using past good experiences. In case that Self-Imitation Learning is combined with reinforcement learning algorithms that have actor-critic architecture, it shows performance improvement in various game environments. However, its applications are limited to reinforcement learning algorithms that have actor-critic architecture. In this paper, we propose a method of applying Self-Imitation Learning to Deep Q-Network which is a value-based deep reinforcement learning algorithm and train it in various game environments. We also show that Self-Imitation Learning can be applied to Deep Q-Network to improve the performance of Deep Q-Network by comparing the proposed algorithm and ordinary Deep Q-Network training results.

• Tribology and Lubricants
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• v.37 no.6
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• pp.213-223
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• 2021

Electrochemical mechanical planarization (ECMP) was developed to overcome the shortcomings of conventional chemical mechanical planarization (CMP). Because ECMP technology utilizes electrochemical reactions, it can have a higher efficiency than CMP even under low pressure conditions. Therefore, there is an advantage in that it is possible to reduce dicing and erosions, which are physical defects in semiconductor CMP. This paper summarizes the papers on ECMP published from 2003 to 2021 and analyzes research trends in ECMP technology. First, the material removal mechanisms and the configuration of the ECMP machine are dealt with, and then ECMP research trends are reviewed. For ECMP research trends, electrolyte, processing variables and pads, tribology, modeling, and application studies are investigated. In the past, research on ECMP was focused on basic research for the development of electrolytes, but it has recently developed into research on tribology and process variables and on new processing systems and applications. However, there is still a need to increase the processing efficiency, and to this end, the development of a hybrid ECMP processing method using another energy source is required. In addition, ECMP systems that can respond to the developing metal 3D printing technology must be researched, and ECMP equipment technology using CNC and robot technology must be developed.