• Title/Summary/Keyword: Mechanical system

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Implant-supported prosthetic rehabilitation for the edentulous maxilla using the additive manufacturing technology: A case report (레이저 적층 제조 기술을 이용한 상악 무치악 환자의 임플란트 고정성 보철 수복 증례)

  • Kim, Hee-Kyung
    • The Journal of Korean Academy of Prosthodontics
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    • v.56 no.2
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    • pp.173-178
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    • 2018
  • The direct metal laser sintering (DMLS) technique would be promising for the full-arch implant-supported restorations due to reduced cost and manufacturing time without potential human errors and casting defects. The aims of this case report were to describe the successful outcome of an implant-supported fixed dental prosthesis in the edentulous maxilla by using the DMLS technology and computer-aided design and computer-aided manufacturing (CAD/CAM) monolithic zirconia crowns, and to describe its clinical implications. A healthy 51-year-old Korean woman visited Seoul National University Dental Hospital and she was in need of a rehabilitation of her entire maxilla due to severe tooth mobility. In this case, all maxillary teeth were extracted and an implant-supported fixed dental prosthesis was fabricated that involved a cobalt-chromium (Co-Cr) framework with the DMLS technique and CAD/CAM monolithic zirconia crowns. Six months after delivery, no distinct mechanical and biological complications were detected and the prosthesis exhibited satisfactory esthetics and function. In this case report, with the DMLS system, the three-dimensional printed prosthesis was created without additional manual tooling and thus, reliable accuracy and passive fit were obtained.

Investigating the Au-Cu thick layers Electrodeposition Rate with Pulsed Current by Optimization of the Operation Condition

  • Babaei, Hamid;Khosravi, Morteza;Sovizi, Mohamad Reza;Khorramie, Saeid Abedini
    • Journal of Electrochemical Science and Technology
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    • v.11 no.2
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    • pp.172-179
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    • 2020
  • The impact of effective parameters on the electrodeposition rate optimization of Au-Cu alloy at high thicknesses on the silver substrate was investigated in the present study. After ensuring the formation of gold alloy deposits with the desired and standard percentage of gold with the cartage of 18K and other standard karats that should be observed in the manufacturing of the gold and jewelry artifacts, comparing the rate of gold-copper deposition by direct and pulsed current was done. The rate of deposition with pulse current was significantly higher than direct current. In this process, the duty cycle parameter was effectively optimized by the "one factor at a time" method to achieve maximum deposition rate. Particular parameters in this work were direct and pulse current densities, bath temperature, concentration of gold and cyanide ions in electrolyte, pH, agitation and wetting agent additive. Scanning electron microscopy (SEM) and surface chemical analysis system (EDS) were used to study the effect of deposition on the cross-sections of the formed layers. The results revealed that the Au-Cu alloy layer formed with concentrations of 6gr·L-1 Au, 55gr·L-1 Cu, 24 gr·L-1 KCN and 1 ml·L-1 Lauryl dimethyl amine oxide (LDAO) in the 0.6 mA·cm-2 average current density and 30% duty cycle, had 0.841 ㎛·min-1 Which was the highest deposition rate. The use of electrodeposition of pure and alloy gold thick layers as a production method can reduce the use of gold metal in the production of hallow gold artifacts, create sophisticated and unique models, and diversify production by maintaining standard karats, hardness, thickness and mechanical strength. This will not only make the process economical, it will also provide significant added value to the gold artifacts. By pulsating of currents and increasing the duty cycle means reducing the pulse off-time, and if the pulse off-time becomes too short, the electric double layer would not have sufficient growth time, and its thickness decreases. These results show the effect of pulsed current on increasing the electrodeposition rate of Au-Cu alloy confirming the previous studies on the effect of pulsed current on increasing the deposition rate of Au-Cu alloy.

Statical Analysis of Cable-Stayed Bridge (사장교(斜張橋)의 정적(靜的) 해석(解析)에 관한 연구(硏究) - 수치계산(數値計算)을 중심(中心)으로 -)

  • Park, Choon Hyok;Bae, Joo Sung;Yang, Seung Hyeon;Cho, Sang Kil
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.5 no.1
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    • pp.13-20
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    • 1985
  • Two Cable-Stayed bridge on south coast in Korea has not constructed until a quarter of a century past since the beginning of it's own era. Our country is about to be interested in such a type of bridge. It has succeeded in constructing the 500 m spanned bridge against wind and earthquake in other several countries. Many contries are striving for designning a long spanned bridge to 1000m. For the realization of such a long spanned bridge in Korea clues to the problems, "How to design it", should be solved one by one. One of difficulties is in analysing the mechanical system because of multi-orter indeterminacy. In this study one of the numerical methods is proposed in order to eliminate the troublesome.

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A Study on Fatigue Characteristic of Stent Using Finite Element Analysis (나이티놀 와이어 스텐트의 피로도 특성에 대한 유한요소 해석)

  • Kim, Han-Ki;Shin, Il-Gyun;Kim, Dong-Gon;Kim, Seong-Hyeon;Lee, Ju-Ho;Ki, Byoyng-Yun;Suh, Tae-Suk;Kim, Sang-Ho
    • Progress in Medical Physics
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    • v.20 no.3
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    • pp.119-124
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    • 2009
  • Stents are frequently used throughout the human body. They keep pathways open in vascular or nonvascular duct for a long time. Therefore its stability is very important factor. In recent years, aconsiderable amount of research has been carried out in order to estimate mechanical properties of the stent such as expansion pressure behavior, radial recoil and longitudinal recoil using FEM (Finite element analyses). However, published works on simulation of stent fatigue behavior using FEM are relatively rare. In this paper, a nonlinear finite-element methodwas employed to analyses the compression of a stent using external pressure and fatigue behavior. Finite element analyses for the stent system were performed using NASTRAN FX. In conclusion this paper shows how the stent is behaved in the body, and its fatigue behavior.

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Comparative Analysis of Treatment Planning System and Dose Distribution of Gamma knife PerfexionTM using EBT-3 Film (EBT-3 필름을 사용한 감마나이프 퍼펙션TM의 치료 계획 시스템 및 선량 분포 비교 분석)

  • Jin, Seongjin;Kim, eongjin;Seo, Weonseop;Hur, Beongik
    • Journal of the Korean Society of Radiology
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    • v.11 no.6
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    • pp.509-515
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    • 2017
  • The purpose of this study is to measure the 3 dimensional dose distribution of Gamma knife $Perfection^{TM}$, make a comparative analysis of the result and establish the measurement method for the procedures using EBT3 film. The dose distributions of the Gamma knife $Perfection^{TM}$ installed in two hospitals were evaluated in accuracy and precision. For accuracy, the difference between the mechanical center axis and the dose center axis was assessed on a 4 mm collimator. The allowed difference in accuracy is within 0.3 mm and it was measured as 0.098 mm, 0.195 mm for A hospital and 0.229 mm, and 0.223 mm for B hospital. For precision the difference between the FWHM(Full Width at Half Maximum) of Gamma Plan and measurement in the 4, 8, and 16 mm collimators was calculated. The allowed difference in precision is less than ${\pm}1mm$. The value of the hospital A was -0.283 ~ 0.583 mm, and the hospital B was -0.857 ~ 0.810 mm. When analyzing the dose distributions using the image-j program, it is necessary to establish a clearer reference point of the measurement point, and it is considered that the comparison of the dose distribution should be performed in actual treatment irradiation dose with a high dose usable film.

Development of a Solar Powered Water Pump by Using Low Temperature Phase Change Material ­ System Construction and Operation Analysis ­ (저온 상변화 물질 특성을 이용한 태양열 물펌프 실용화 연구개발(II) ­시스템 구성 및 작동분석)

  • 김영복;이양근;이승규;김성태;나우정;민영봉
    • Journal of Animal Environmental Science
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    • v.9 no.2
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    • pp.69-78
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    • 2003
  • In this study, the energy conversion equipment from the radiation energy to mechanical energy by using n­pentane as the operating fluid was constructed and the performance to pump the water was tested for the utilization of solar powered water pump. The equipment was designed optimally, after the theoretical analyses of the water pumping head and water quantity per cycle were done. The pentane vapour temperature in the condenser and the temperature of the outlet water from the condenser became lowered and the heat transfer rate became higher with decreasing the water inlet level to the condenser. The temperature difference between the condenser and the water tank was significant. Therefore, the distance between the water tank and condenser was recommended to be shorten and the diameter of their connecting pipe was recommended to be narrow in order to reduce the resistance of the fluid passage and improve the heat transfer rate. The amount of water pumped was 1.6­2.4 liters. Mass flow rate of the cooling water became lowered when the cooling water pipe was prolonged from the condenser to improve the heat transfer rate.

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Molecular Theory of Plastic Deformation (I). Theory (소성변형의 분자론 (제1보). 이론)

  • Kim Chang Hong;Ree Taikyue
    • Journal of the Korean Chemical Society
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    • v.21 no.5
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    • pp.330-338
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    • 1977
  • In order to elucidate the plastic deformation of solids, the following assumptions were made: (1) the plastic deformation of solids is classified into two main types, the one which is caused by dislocation movement and the other caused by grain boundary movement, each movement being restricted on a different shear surface, (2) the dislocation movement is expressed by a mechanical model of a parallel connection of various kinds of Maxwell dislocation flow units whereas the grain boundary movement is also expressed by a parallel connection of various kinds of Maxwell grain boundary flow units; the parallel connection in each type of movements indicates that all the flow units on each shear surface flow with the same shear rate, (3) the latter model for grain boundary movement is connected in series to the former for dislocation movement, this means physically that the applied stress distributes homogeneously in the flow system while the total strain rate distributes heterogeneously on the two types of shear planes (dislocation or grain boundary shear plane), (4) the movement of dislocation flow units and grain boundary units becomes possible when the atoms or molecules near the obstacles, which hinder the movement of flow units, diffuse away from the obstacles.Using the above assumptions in conjunction with the theory of rate processes, generalized equations of shear stress and shear rate for plastic deformation were derived. In this paper, four cases important in practice were considered.ted N${\cdot}{\cdot}{\cdot}$O hydrogen bond and the second of two normal N${\cdot}{\cdot}{\cdot}$O hydrogen bonds, both of which exist between the amino group and the perchlorate, groups. A p-phenylenediamine group is approximately planar within an experimental error and bonded to twelve perchlorates: ten perchlorates forming hydrogen bonds and two being contacted with the van der Waals forces. A perchlorate group is surrounded by six p-phenylenediamines and four perchlorates; among the six p-phenylenediamines, five of them are hydrogen-bonded, and the rest contacted with the van der Waals force.

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Fabrication of a Ultrathin Ag Film on a Thin Cu Film by Low-Temperature Immersion Plating in an Grycol-Based Solution (글리콜 용매 기반 저온 치환 은도금법으로 형성시킨 동박막 상 극박 두께 Ag 도금층)

  • Kim, Ji Hwan;Cho, Young Hak;Lee, Jong-Hyun
    • Journal of the Microelectronics and Packaging Society
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    • v.21 no.2
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    • pp.79-84
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    • 2014
  • To investigate the plating properties of a diethylene glycol-based Ag immersion plating solution containing citric acid, silver immersion plating was performed in a range from room temperature to $50^{\circ}C$ using sputtered Cu specimens. The used Cu specimens possessed surface structure with large numbers of pinholes which were created with over-acid etching. The Ag immersion plating performed at $40^{\circ}C$ exhibited that the pinholes and copper surface were completely filled with Ag just after 5 min mainly due to galvanic displacement reaction, indicating the best plating properties. Subsequently, the surface morphology of Ag-coated Cu became rougher as the plating time increased to 30 min because of the deposition of silver nanoparticles created by chemical reduction in the solution. The specimen that its overall surface was covered with silver indicated the start of oxidation at temperature higher than around $50^{\circ}C$ in air as compared with pure Cu, indicating enhanced anti-oxidation properties.

Thermal Analysis of 3D package using TSV Interposer (TSV 인터포저 기술을 이용한 3D 패키지의 방열 해석)

  • Suh, Il-Woong;Lee, Mi-Kyoung;Kim, Ju-Hyun;Choa, Sung-Hoon
    • Journal of the Microelectronics and Packaging Society
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    • v.21 no.2
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    • pp.43-51
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    • 2014
  • In 3-dimensional (3D) integrated package, thermal management is one of the critical issues due to the high heat flux generated by stacked multi-functional chips in miniature packages. In this study, we used numerical simulation method to analyze the thermal behaviors, and investigated the thermal issues of 3D package using TSV (through-silicon-via) technology for mobile application. The 3D integrated package consists of up to 8 TSV memory chips and one logic chip with a interposer which has regularly embedded TSVs. Thermal performances and characteristics of glass and silicon interposers were compared. Thermal characteristics of logic and memory chips are also investigated. The effects of numbers of the stacked chip, size of the interposer and TSV via on the thermal behavior of 3D package were investigated. Numerical analysis of the junction temperature, thermal resistance, and heat flux for 3D TSV package was performed under normal operating and high performance operation conditions, respectively. Based on the simulation results, we proposed an effective integration scheme of the memory and logic chips to minimize the temperature rise of the package. The results will be useful of design optimization and provide a thermal design guideline for reliable and high performance 3D TSV package.

Inspection of the Nuclear Fuel Rod Deformation using an Image Processing (영상처리를 이용한 핵연료봉의 변형 검사)

  • Cho, Jai-Wan;Choi, Young-Soo
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.47 no.1
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    • pp.91-96
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    • 2010
  • In this paper, a deformation measurement technology of the nuclear fuel rod is proposed. The deformation measurement system include high definition CCD or CMOS image sensor, lens, semiconductor laser line beam marker, and optical & mechanical accessories. The basic idea of the deformation measurement is to illuminate the outer surface of the fuel rod with collimated laser line beam at an angle of 45 degrees or higher. The relative motion of the fuel rod in the horizontal direction causes the illuminated laser line beam to move vertically along the surface of the fuel rod. The resulting change of laser line beam position in the surface of the fuel rod is imaged as the parabolic beam in the high definition CCD or CMOS image sensor. From the parabolic beam pattern, the ellipse model is extracted. And the slope of the long and the short axis of the ellipse model is found. The crossing point between the saddle point of the parabolic beam and the long & short axis of the ellipse model is taken as the feature of the deformed fuel rod. The vertical offset between feature points before and after fuel rod deformation is calculated. From the experimental results, $50\;{\mu}m$ inspection resolution is acquired using the proposed method, which is three times enhanced than the conventional criterion ($150\;{\mu}m$) of the guide for the inspection of the nuclear fuel rod.