Sealing Behavior Research on the Radial Ferrofluid Seal Structure with Oblique Teeth

Fang Yuan,Siqi Wang,Decai Li,Long Che 한국자기학회 2022 Journal of Magnetics Vol.27 No.1

Considering various unstable factors when the large-diameter spindle operates at a high speed, such as eccentricity, centrifugal force, etc., the ordinary ferrofluid seal structures will show poor sealing performance. This paper proposes an axial-radial bidirectional ferrofluid seal structure with radial oblique teeth to improve the sealing performance. The pressure resistance of the radial ferrofluid seal structure in the magnetic circuit is theoretically analyzed. The magnetic flux distribution characteristic in the gap of the oblique teeth is studied by magnetic field simulation. According to the analysis results of the magnetic induction intensity, to obtain the larger theoretical pressure resistance, the optimal angle of oblique teeth is 77.87°, 64.28° and 62.81° under the radial seal structure with different gaps of 0.1 mm, 0.15 mm and 0.2 mm, respectively. In addition, simulation analysis is carried out to obtain the fluid pressure and velocity distribution of the radial ferrofluid seal structure with different oblique teeth angles. When the oblique teeth angle is small, the pressure drops and gas flow speeds in the ferrofluid area are all lower, and the pressure resistance is higher.

Glide path 형성용 니켈티타늄 회전 파일의 효율

김현철(Hyeon-Cheol Kim),곽상원(Sang Won Kwak),하정홍(Jung-Hong Ha) 대한치과의사협회 2017 대한치과의사협회지 Vol.55 No.10

Objectives: This preliminary study compared the effects of glide path establishing instruments prior to substantial root canal preparation. Materials and Methods: Glide path was established by enlargement of the 2nd mesiobuccal root canal of Dentalike by using three kinds of glide path preparation nickel-titanium file; PathFile, One G and ProGlider. The pre- and post-instrumented Dentalikes were weighed in the resolution of 1/10㎎. In addition, after glide path preparation, torque generated during shaping using the WavoOne file was measured. The data were analyzed by one-way ANOVA and Tukey post-hoc test at a significance level of 95%. Results: The ProGlider had the significantly larger amount of reduced weight than other instrument groups (p<0.05). There was no significant difference between group of glide path preparation with ProGlider and without glide path preparation in maximum torque and total stress generation during the shaping with WaveOne. Conclusions: Glide path preparation instruments may have different efficiency according to their geometries. The Dentalike artificial teeth were revealed to have discrepancies in the size of root canals by microCT examination. It is impossible to make a meaningful judgment of the results due to the reliability or resolution problem of the root canal size of the artificial tooth selected as the standardized tooth.

Tooth Brushing Instruction System by Use of 3D Motion Capturing Digital Simulation Program with 3-axis Accelerometer

Seung-Hoon Lee,Kwang-Young Kim,Eun-Joo Na,Ja-Won Cho 대한예방치과학회 2013 International Journal of Clinical Preventive Denti Vol.9 No.4

Objective: In order to compare the tooth brushing instruction effect between the traditional method and the using the 3D axis accelerated simulation system. Methods: The authors have examined PHP index for 88 patients who had performed the rolling method of toothbrushing instructed by a dental hygienist as 45 persons for control group and 43 as an experimental group as instructed by a 3D motioned simulation system which had been devised the program. In the same way, 33 for control group and 31 for experiment as total 64 orthodontic patients were participated for tooth brushing instruction for charters method on the bracket area, by a dental hygienist for control group and by use of 3D motioned simulation system as an experimental group. The results for PHP index between two groups as rolling method or Charters method for as Orthodontic braced patients, The PHP index changes according to the periods were revealed. Results: The decreasing rate of PHP index were shown as 0.58±0.74 in control, otherwise as 1.02±1.11 in experimental group for normal patients (p<0.05), but, 0.80±0.61 in control group and 1.03±1.06 in experimental group for Orthodontic patients (p>0.05). Conclusion: It was recommended th use and to apply for 3D motioned simulation system for tooth brushing instruction at the dental clinics because of the more effective than that of the instructor’s training.

Tooth Brushing Instruction System by Use of 3D Motion Capturing Digital Simulation Program with 3-axis Accelerometer

이승훈,김광영,나은주,조자원 대한예방치과학회 2013 International Journal of Clinical Preventive Denti Vol.9 No.4

Objective: In order to compare the tooth brushing instruction effect between the traditional method and the using the 3D ax- is accelerated simulation system. Methods: The authors have examined PHP index for 88 patients who had performed the rolling method of toothbrushing in- structed by a dental hygienist as 45 persons for control group and 43 as an experimental group as instructed by a 3D mo- tioned simulation system which had been devised the program. In the same way, 33 for control group and 31 for experiment as total 64 orthodontic patients were participated for tooth brushing instruction for charters method on the bracket area, by a dental hygienist for control group and by use of 3D motioned simulation system as an experimental group. The results for PHP index between two groups as rolling method or Charters method for as Orthodontic braced patients, The PHP index changes according to the periods were revealed. Results: The decreasing rate of PHP index were shown as 0.58±0.74 in control, otherwise as 1.02±1.11 in experimental group for normal patients (p<0.05), but, 0.80±0.61 in control group and 1.03±1.06 in experimental group for Orthodontic patients (p>0.05). Conclusion: It was recommended th use and to apply for 3D motioned simulation system for tooth brushing instruction at the dental clinics because of the more effective than that of the instructor’s training.

High-efficiency technique for five-axis side milling of niemann worm wheels

Haibing Wu,Zheng Zhang,Quanping Sun 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6

Five-axis side milling technique for Niemann worm wheel teeth flank using a tapered flat-end mill is presented. Equations describing the worm wheel tooth flank were derived based on differential geometry and the working principle of gears. The tooth flank was modified by offsetting its point cloud computed using these equations along the normal direction. The maximum normal curvature of the worm wheel tooth flank was computed, and its minimum radius of curvature was obtained. The cutter path step length and spacing between cutter travels were computed to generate a uniform path for five-axis machining. Software simulations of the cutter path were performed for validation and for analysing errors in the worm wheel tooth flank machining; this technique was also verified by milling worm wheels. The results demonstrated that the technique not only improved machining efficiency by 5 times compared with point milling but also guaranteed precision machining of the tooth flank for five-axis machining of cylindrical worm drives.

환자맞춤형 3D 프린팅 모델을 활용한 매복 사랑니 발치 실습의 교육적 효과: 예비 연구

정서연,김수연,최이슬,박원서 대한통합치과학회 2022 대한통합치과학회지 Vol.11 No.2

Tooth extraction is a skill that must be competent to provide primary care as a general dentist after graduating from dental college. However, compared to simple extraction, surgical extraction is not only difficult to perform, there is a risk of surgery, and dental students have fewer opportunities to treat patients, making it difficult to be competent. Therefore, we developed a surgical simulation of the impacted third molar extraction course using patient-specific 3D printing model. This study aims to analyze the educational effect of this practice by content analysis of reflection writing of students who actually performed the operation after simulation using a 3D printing model. As a result of content analysis for students’ reflective writing, it was found that surgical simulation using the 3D printing model greatly contributed to the motivation for self-directed learning as well as the improvement of students’ knowledge and skills. In conclusion, through surgical simulation course accompanied by reflection writing, dental students can improve the ability to perform surgical extraction and induce self-directed learning.

전기자동차용 지로터 펌프의 가상 설계 환경 구축 사례

노대경,이동원,윤영환,전정배 한국시뮬레이션학회 2023 한국시뮬레이션학회 논문지 Vol.32 No.2

The purpose of this study is to create virtual design environment that can predict performance in various situations by reflecting the static design data of a gerotor pump to a dynamic behavior analysis model. The virtual design environment is created through systematic connection between tooth profile creation program that can present drawing specification and analysis model which can review dynamic performance. The study is carried out in the following manner. First, tooth is designed by using tooth profile creation program developed in the previous study and volume change is derived depending on the rotation angle of rotor. Second, analysis model, which can review the behavior of gerotor pump by chamber, is developed through SimulationX, a software specialized in multi domain analysis. Third, design data from tooth design program is mapped on the analysis model in order to link the two programs. Lastly, behaviors such as the pressure and flow pulsation of gerotor pump are realized in order to review the feasibility of connected virtual design environment. In conclusion, a virtual design environment for the gerotor pump was created, which is expected to reduce the time and cost required for design and verification. 본 연구의 목적은 지로터 펌프의 정적인 설계 데이터를 동적 해석모델에 반영하여 다양한 상황에서 성능을 예측할 수 있는 가상 설계 환경을 구축하는데 있다. 가상 설계 환경은 도면 사양을 도출할 수 있는 치형 프로파일 생성 프로그램과 동역학적인 성능을 검토할 수 있는 해석모델의 유기적인 연결을 통해 구축된다. 이를 위한 연구 방법은 다음과 같다. 우선 선행연구를 통해 개발된 치형 프로파일 생성 프로그램을 이용하여 치형을 설계하고 로터 회전 각도에 따른 용적변화를 도출한다. 그리고 멀티도메인 해석소프트웨어인 SimulationX를 통해 지로터 펌프의 챔버별 거동을 분석할 수 있는 해석모델을 개발한다. 이후 해석모델에 치형 설계 프로그램에서 도출된 설계 데이터를 매핑하여 두 프로그램을 연계한다. 마지막으로 연계된 가상 설계 환경의 타당성을 검토하기 위하여 지로터 펌프의 압력과 유량맥동 등의 거동을 구현한다. 결론적으로 지로터 펌프의 가상 설계 환경을 구축하였으며, 이를 통해 설계와 검증에 소요되는 시간과 비용을 절감할 수 있을 것으로 기대된다.

Simulated Damaged Nuclear Fuel Rod Manufacturing Device

Kweonho Kang,Jooho Lee,Sunseok Hong,Changhwa Lee,Yongjun Cho 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

In general, if a nuclear fuel cladding tube is damaged during reactor operation, it is called fuel failure. If the cladding tube is damaged, the function of sealing the nuclear fuel material is lost, and the fission products accumulated inside the nuclear fuel rod may leak into the coolant. The causes are the most damage caused by foreign substances in a coolant such as small iron wires, and GTRF (Gridto- Rod Wear) due to a grid, end-plug welding defect, PCMI (pellet cladding mechanical interaction), and oxidation corrosion damage. In this study, a device of simulating friction damage and debris induced damage between grid-fuel rods, which are the main causes of cladding tube damage, was developed. An air vibrator was installed as a function to induce vibration of the nuclear fuel rod. Sandpaper was installed between the grid and the fuel rod to induce friction between the grid-fuel rods. Saw teeth were installed on the grid to induce damage to foreign substances. It is believed that the simulated damaged nuclear fuel rod can be manufactured through on-study to provide the simulated damaged nuclear fuel rod necessary for the stabilization study of the damaged nuclear fuel rod.

Finite Element Simulation for Pick-up Tooth of Combine

J. R. Kim(김진록),T. H. Kwon(권태하),C. H. Suh(서창희),J. G. Song(송준국),M. S. Ju(주민수) 한국소성가공학회 2015 한국소성가공학회 학술대회 논문집 Vol.2015 No.5

성공적인 선 수술 교정 치료를 위한 고려사항

오창옥(Changok Oh) 대한치과의사협회 2012 대한치과의사협회지 Vol.50 No.2

The fundamental principles and the role of surgeons and orthodontists to produce successful results in orthodontic treatment combined with orthognathic surgery is not different from those of conventional procedures and FOS: surgery-first-orthodontictreatment-later approach. The communication and cooperation between surgeon and orthodontist is of crucial importance. In FOS, the pre-surgical orthodontic preparation is not carried out in the patient"s mouth, but in the mounted stone model and in addition to the simulation of tooth movement, to get a precise surgical occlusion, the entire steps of treatment should be simulated on the articulator as well. Right after the surgery, due to the instability of the occlusion, appropriate post operational care should be given according to the surgical technique applied to the mandible by use of final surgical wafer about 8 weeks.