Effect of Workpiece Atom Diffusion into CBN Tool on its Mechanical Properties in Cutting Ni–Fe–Cr Alloy Based on Molecular Dynamics Simulation

Yi Hang Fan,Wen Yuan Wang,Zhao Peng Hao,Hengyi Yuan 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.4

CBN (Cubic Boron Nitride) tool is suitable for precision machining of nickel-based alloy due to its high hardness and chemical inert. Nickel-based alloys are difficult-to-cut material. When high-speed cutting nickel-based alloys with CBN tool, the temperature at tool-workpiece interface is very high. The atoms in workpiece material diff use into the tool surface and change the performance of cutting tool, resulting in diffusion wear. Inconel 718, which is one kind of widely used nickel-based alloy, is mainly composed of nickel (Ni), iron (Fe) and chromium (Cr). In this paper, the cutting model which describes the single crystal CBN tool cutting Ni–Fe–Cr three-component alloy, and the compression and impact model of CBN tool crystal are established by using molecular dynamics (MD) method to study the diffusion of Ni, Fe and Cr atoms into CBN tool and the effects of diffusion on the properties of CBN crystal tool. The results show that the diffusion of Ni, Fe and Cr atoms into CBN tool decreases the compressive strength and impact toughness of CBN crystals and the effects degree of atom diffusion on the properties of CBN crystals are different.

Thyroid Fine-Needle Aspiration in Taiwan: The History and Current Practice

Jen-Fan Hang,Chiung-Ru Lai,Chih-Yi Hsu 대한병리학회 2017 Journal of Pathology and Translational Medicine Vol.51 No.6

In Taiwan, thyroid cancer is the most common endocrine gland malignancy and the incidence of thyroid cancer has increased four-fold in the past two decades. Fine-needle aspiration is an accurate and cost-effective method of evaluating thyroid nodules and has been the gold-standard diagnostic tool for thyroid tumors in Taiwan since the 1980s. This article reviews the history, current practice, reporting systems, training, and quality assurance for thyroid fine-needle aspiration cytology in Taiwan.

Performance Improvement with a Combined Scheme of Rapid Thermal Annealing and Multi-channel Structure for Poly-Si TFTs with Various Device Dimensions

Ching-Lin Fan,Yi-Yan Lin,Yan-Hang Yang 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.8

This study presents a combined scheme of rapid thermal annealing (RTA) and multi-channel structure for improving the performance of polycrystalline silicon (poly-Si) thin film transistors (TFTs). Results show that RTA treatment can improve device performance by decreasing the number of in-grain defects and improving the quality of the gate oxide. The multi-channel structure improves the electrical characteristics of the poly-Si TFTs by decreasing the number of grainboundary defects. Thus, the combined scheme can effectively reduce defect states and improve the gate-oxide’s quality simultaneously, resulting in a significant improvement in the performance of poly-Si TFTs. In addition, the performance improvement is particularly apparent for the TFTs with a thinner gate oxide and smaller channel length. Therefore, the proposed scheme is a good candidate for improving the electrical characteristics of TFTs for use in small-to-medium size displays.

The evaluation of online course of Traditional Chinese Medicine for Medical Bachelor, Bachelor of Surgery international students during the COVID-19 epidemic period

Zhang Qing,He Yi-Jing,Zhu Yu-Hang,Dai Min-Chen,Pan Man-Man,Wu Jia-Qi,Zhang Xian,Gu Ying-Er,Wang Fang-Fang,Xu Xiang-Rong,Qu Fan 한국한의학연구원 2020 Integrative Medicine Research Vol.9 No.3

Background: During the COVID-19 epidemic period, Traditional Chinese Medicine (TCM) course for international students of Medical Bachelor, Bachelor of Surgery (MBBS) program in Zhejiang University has shifted from traditional classroom to online environment. This study aimed to investigate MBBS international students’ perception on online TCM course, and to assess the online learning efficacy. Methods: A total of 84 MBBS international students attending course of “Basic Traditional Chinese Medicine” during 2020 academic years at Zhejiang University were enrolled in this study. A quantitative questionnaire was respectively completed before and after the TCM course using a pretest–post-test design. By means of two online learning platforms, Learning in ZJU and DingTalk, TCM course was broadcast in both live and archived format to students. Results: A total of 48 participants completed both baseline and follow-up questionnaires. The majority of participants preferred face-to-face classroom learning (26, 54.17% of total) when compared with online learning. Students felt that the course had brought in much benefits (mean 3.88, SD 0.87), and they were satisfied with the course content (mean 3.83, SD 0.95). Students’ TCM related knowledge and their behaviors of discussion and consulting were significantly improved by online TCM course (all P < 0.001). Students’ awareness of the necessity of TCM education and their feeling of difficulty in learning TCM were significantly strengthened (P = 0.042, 0.025, respectively). Conclusion: Online learning is a good alternative for TCM course of MBBS international students when classroom learning is suspended, whereas it cannot replace the need for onsite and face-to-face learning.

Thyroid fine-needle aspiration cytology in Taiwan: a nationwide survey and literature update

Chien-Chin Chen,Jen-Fan Hang,Chih-Yi Liu,Yeh-Han Wang,Chiung-Ru Lai 대한병리학회 2020 Journal of Pathology and Translational Medicine Vol.54 No.5

In Taiwan, thyroid fine-needle aspiration cytology is easily accessible and reliable for evaluating thyroid nodules. The sonographic pattern plays a major role and is the deciding factor for aspiration. We conducted a nationwide survey in 2017 and it revealed that 31% of laboratories had adopted The Bethesda System for Reporting Thyroid Cytopathology. There was a relatively high unsatisfactory rate (24.04%) and low rates of indeterminate diagnoses, including atypia of undetermined significance/follicular lesions of undetermined significance: 4.87%, and follicular neoplasm/suspicious for a follicular neoplasm: 0.35%. Moreover, the risks of malignancy in benign, atypia of undetermined significance, and suspicious for a follicular neoplasm were relatively high. These may reflect strict diagnostic criteria for indeterminate categories and better patient selection for surgery. Improvements in specimen sampling and continuing education programs are crucial. Newly-developed thyroid cytology technologies, such as immunocytochemistry, molecular testing, and computerized cytomorphometry, may further facilitate cytology diagnoses.

Microscopic Study on the Mechanism of Tool Bond Wear in Cutting Ni–Fe-Cr-Co–Cu Series Nickel-Base Superalloy

Zhao Peng Hao,Xue Han,Yi Hang Fan,Zai Zhen Lou 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.4

In the process of nickel-based alloy machining, chips are easy to bond on the tool surface, which weaken the tool performance and make the tool wear. Therefore, it is very important to study the mechanism of tool bond wear in the process of nickel-based superalloy machining. In order to reflect the wear process of the tool from the perspective of micro cutting, the molecular dynamics simulation model for cutting Ni–Fe-Cr-Co–Cu nickel-based alloy with SiC tool was established. The Morse potential functions between the tool and workpiece are calculated, and the simulation results are analyzed visually. It is found that the bond wear is the main wear form of tool in the process of cutting nickel-based alloy, and the wear processes are divided into three stages: contact, adhesion and shedding. The stress and strain in the cutting area are calculated and it is found that the bond occurs when the tool-workpiece extrusion is strong. Through the calculation of radial distribution function and formation energy, it is found that Ni-Si compound is formed on the tool surface, and the newly generated Ni-Si compound reduces the tool performance compared with the silicon carbide structure. This study provides a more complete microscopic explanation of the tool wear mechanism, which is helpful to find a method to prolong tool life.