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Taeho Jang,Wonseok Yang,Sungyeol Choi 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
Measuring the concentration of corrosion products or nuclear fission products (FPs) in molten salts is crucial for pyroprocessing and molten salt reactors. Electrochemical analysis methods that can be performed in situ offer significant advantages for monitoring the concentration of corrosion products or FPs in molten salts. A microelectrode is an electrode with a length of several tens of micrometers on one side. The use of a microelectrode for electrochemical analysis has several advantages due to its small size, including rapidly reaching the limiting current regardless of the scan rate, immediate attainment of the limiting current upon applying an overpotential for instant monitoring within milliseconds, accurate measurement even in low convection systems, a small iR drop resulting from low flowing current and high signal accuracy, and high current density resulting in a high signal-tonoise ratio (SNR). Among various methods for making microelectrodes, techniques involving cutting a thin wire or using capillaries (such as the dual-bore capillary and pulled glass capillary methods) require precise manual skills and experience. Therefore, the results may vary depending on the maker’s skill level, and it can be difficult to control the electrode’s area, thickness, and surface uniformly. Recent research has focused on using semiconductor processes to fabricate microelectrodes, where CVD, metal sputtering, photolithography, and etching processes work together to deposit, refine, and shape the required material on a silicon wafer to create microelectrodes. However, the durability of microelectrodes produced this way is still low (usable for about 15-30 minutes), and there is no clear research on the degradation mechanism over time. To verify the proper operation of the fabricated microelectrodes, cyclic voltammetry (CV) is performed at various scan rates (from 10 mVs-1 to 2 Vs-1), and chronoamperometry (CA) is also examined to confirm whether the electrodes rapidly reach a steady-state current. After confirming their proper operation, CV is continuously measured until the microelectrodes are destroyed in a LiCl-KCl solution containing a small amount of FPs (Sm 340 mM) at 450°C. By observing changes in the electrical signal of the microelectrodes over time, the durability is evaluated, and the mechanism of performance degradation of the electrode is discovered. The experiment is then repeated by gradually increasing the temperature by 30°C from 450°C up to 600°C to observe the changes with temperature. This study provides basic information for future microelectrode experiments, and by diagnosing the cause of destruction, a more durable microelectrode structure can be manufactured.
A Novel Registration Method for Total Knee Arthroplasty Using a Patient-Specific Registration Guide
Taeho Jang,Kunwoo Lee 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
Total knee arthroplasty is a surgical method for replacing the entire knee joint by inserting an artificial knee implant into the distal femur and proximal tibia. To improve total knee arthroplasty outcomes, a registration process is essential for determining the exact location of the pre-determined bone-cutting area by calculating the positions and postures of the femur and tibia. In this paper, we suggest a patient-specific registration guide, which can drastically reduce the time and effort required for the registration process and provide real-time tracking potential. Because the patient-specific registration guide has the same surface shape as a pre-acquired 3-D model of the patient’s femur and tibia, the registration process can be achieved by fitting the registration guide onto the proper bone area. To verify the registration guide’s precision and accuracy, a digitizer and linear motion generator were used. The mean registration error of our method was 0.016mm, and this high accuracy can be obtained in less time than existing registration methods.
Jang, Taeho,Lee, Kunwoo SAGE Publications 2014 Surgical innovation Vol.21 No.1
<P>Total knee arthroplasty (TKA) is a surgical method for replacing a degenerated or diseased knee joint that can no longer perform daily functions with an artificial knee implant. In TKA, the artificial knee implant should be inserted such that it aligns well with the mechanical axis of the leg. Thus, precise bone cutting is essential. To improve TKA outcomes, a registration process is performed to locate the predetermined bone cutting area by calculating the position and posture of the femur and tibia. In this article, we propose a patient-specific registration guide that is able to significantly reduce registration time and effort without loss of accuracy. Furthermore, the patient-specific registration guide can be implemented with real-time registration, allowing continuous surgical information to be provided without the insertion of any tracking devices. The precision and accuracy of the proposed registration guide were confirmed through animal tests with a digitizer, stereo camera, and linear motion generator. The error of our registration method, including measurement and guide attachment errors, reached a maximum of 0.321 mm for one pair of cow legs.</P>
모바일 로봇 자세 안정화를 위한 칼만 필터 기반 센서 퓨전
장태호(Taeho Jang),김영식(Youngshik Kim),경민영(Minyoung Kyoung),이현빈(Hyunbean Yi),윤동환(Yoondong Hwan) 대한기계학회 2016 大韓機械學會論文集A Vol.40 No.8
로보틱스 연구에서, 모바일 로봇의 모션 제어를 위해서는 로봇의 실제 위치를 정확히 추정하는 것이 중요하다. 이를 위해 본 연구에서는, 두 개의 서로 다른 센서 데이터를 칼만필터로 융합하여 로봇의 위치인식을 개선하는 연구를 진행한다. 칼만필터로 융합한 두 개의 센서 측정값은 카메라 영상으로부터 측정된 모바일 로봇의 전역(global) 위치 좌표(x, y)값과 모바일 로봇 바퀴에 부착된 엔코더로부터 측정된 로봇의 직선 및 각속도 값이다. 다음으로 칼만필터로부터 계산된 모바일 로봇의 위치값을 모바일 로봇의 자세 안정화에 피드백하여 모션 제어의 퍼포먼스를 향상시켰다. 최종적으로 논문에서 제안한 센서융합 위치인식 기술과 모션제어기를 실제 로봇에 적용하여 실험적으로 검증하였다. 또한 모션제어에 단일 센서를 피드백으로 사용한 경우와 칼만필터로 융합한 위치 값을 사용한 경우를 비교하므로 칼만필터 기반 센서 융합 기술을 사용한 경우의 퍼포먼스 향상을 확인하였다. In robotics research, accurate estimation of current robot position is important to achieve motion control of a robot. In this research, we focus on a sensor fusion method to provide improved position estimation for a wheeled mobile robot, considering two different sensor measurements. In this case, we fuse camera-based vision and encode-based odometry data using Kalman filter techniques to improve the position estimation of the robot. An external camera-based vision system provides global position coordinates (x, y) for the mobile robot in an indoor environment. An internal encoder-based odometry provides linear and angular velocities of the robot. We then use the position data estimated by the Kalman filter as inputs to the motion controller, which significantly improves performance of the motion controller. Finally, we experimentally verify the performance of the proposed sensor fused position estimation and motion controller using an actual mobile robot system. In our experiments, we also compare the Kalman filter-based sensor fused estimation with two different single sensor-based estimations (vision-based and odometry-based).
3차원 스캔 데이터를 이용하여 임의의 신체 치수에 대응하는 인체 형상 모델 생성 방법
장태호(Taeho Jang),백승엽(Seungyeob Baek),이건우(Kunwoo Lee) (사)한국CDE학회 2009 한국CDE학회 논문집 Vol.14 No.6
In this paper, we suggest the method for constructing parameterized human body model which has any required body sizes from 3D scan data. Because of well developed 3D scan technology, we can get more detailed human body model data which allow to generate precise human model. In this field, there are a lot of research is performed with 3D scan data. But previous researches have some limitations to make human body model. They need too much time to perform hole-filling process or calculate parameterization of model. Even more they missed out verification process. To solve these problems, we used several methods. We first choose proper 125 3D scan data from 5th Korean body size survey of Size Korea according to age, height and weight. We also did post process, feature point setting, RBF interpolation and align, to parameterize human model. Then principal component analysis is adapted to the result of post processed data to obtain dominant shape parameters. These steps allow to reduce process time without loss of accuracy. Finally, we compare these results and statistical data of Size Korea to verify our parameterized human model.