마이크로 수력 에너지원의 수평축 스크류 터빈 : 설계 타당성 연구

삼수딘 모하메드 무르시드,김승준,마상범,김진혁 한국수소및신에너지학회 2022 한국수소 및 신에너지학회논문집 Vol.33 No.1

Micro hydropower is a readily available renewable energy source that can be harvested utilizing hydrokinetic turbines from shallow water canals, irrigation and industrial channel flows, and run-off river stream flows. These sources generally have low head (<1 m) and low velocity which makes it difficult to harvest energy using conventional turbines. A horizontal-axis screw turbine was designed and numerically tested to extract power from such low-head water sources. The 3-bladed screw-type turbine is placed horizontally perpendicular to the incoming flow, partially submerged in a narrow water channel at no-head condition. The turbine hydraulic performances were studied using Computational Fluid Dynamics models. Turbine design parameters such as the shroud diameter, the hub-to-shroud ratios, and the submerged depths were obtained through a steady-state parametric study. The resulting turbine configuration was then tested by solving the unsteady multiphase free-surface equations mimicking an actual open channel flow scenario. The turbine performance in the shallow channel were studied for various Tip Speed Ratios (TSR). The highest power coefficient was obtained at a TSR of 0.3. The turbine was then scaled-up to test its performance on a real site condition at a head of 0.3 m. The highest power coefficient obtained was 0.18. Several losses were observed in the 3-bladed turbine design and to minimize losses, the number of blades were increased to five. The power coefficient improved by 236% for a 5-bladed screw turbine. The fluid losses were minimized by increasing the blade surface area submerged in water. The turbine performance was increased by 74.4% after dipping the turbine to a bottom wall clearance of 30 cm from 60 cm. The final output of the novel horizontal-axis screw turbine showed a 2.83 kW power output at a power coefficient of 0.63. The turbine is expected to produce 18,744 kWh/year of electricity. The design feasibility test of the turbine showed promising results to harvest energy from small hydropower sources.

마이크로 스크류의 해석기반 판형 전조성형공정 연구

박기동(K. D. Park),송정한(J. H. Song),이혜진(H. J. Lee),이근안(G. A. Lee),이낙규(N. K. Lee),이형욱(H. W. Lee),나승우(S. W. Ra) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.10

There have been strong demands for micro size screw with high precision due to miniaturization and integration trends for electronic products such as Hard Disk Drives. The thread rolling process for screw manufacturing are lower unit cost, reduced material utilization, and superior mechanical properties compared to the machining process. But little work has been done on the thread rolling of micro size screw. In this paper, we investigate thread rolling process using Finite Element Analysis (FEA) and parameter study for screw. In this paper, we investigate thread rolling process using Finite obtain the material property and to implement into the FE tool for the numerical simulation. In case that parameter of relative position of dies is half length of pitch for maintaining the continuous thread profiles, we found that shear friction factor was 0.9 during the thread rolling process using FEA. We are trying to develop the thread rolling process using the FE-simulation to manufacture screws which have been commonly produced from the industrial level fabrication at present.

Workspace analysis of 3-CPS parallel micro-manipulator for mirror active adjusting platform

Gang Cheng,Bing-jing Qiu,De-hua Yang,Hou-guang Liu 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.12

In order to adjust telescope mirrors with high precision, a 3 cylindrical-prismatic-spherical (CPS) parallel micro-manipulator with 6 degrees-of-freedom (DOF) and partial decoupling is proposed. Structure characteristics of the micro-manipulator were analyzed and the kinematic equations were derived based on Euler method. To avoid tedious derivation, Jacobian matrix with screw theory representing the input and output relation of micro-manipulator is established by using velocity influence coefficient method. Combining topological structure characteristics of the 3-CPS parallel micro-manipulator, the solving procedures of workspace are obtained. Moreover, the position workspace with a given orientation and the orientation workspace with a given translation position are constructed by numerical simulations. The workspace range is chosen as the optimization goal of structure parameters, and the circumcircle radius ratio of base and moving platform and the lengths of each sub-link are optimized. The maximum condition number and the minimum singular value are chosen as the precision indexes to analyze the precision performance of the workspace. Then, the properties of the position workspaces with various orientations and the orientation workspaces with various positions are simulated numerically, and the simulation results prove that the 3-CPS parallel micro-manipulator has an ability to achieve high precision operations. This research provides a workspace modeling and optimization method for the practical application in telescope mirror adjustment or other fields requiring high precision.

Detection and Quantification of Screw-Home Movement Using Nine-Axis Inertial Sensors

( Jeong Woo Jeon ),( Dong Yeop Lee ),( Jae Ho Yu ),( Jin Seop Kim ),( Jiheon Hong ) 대한물리치료학회 2019 대한물리치료학회지 Vol.31 No.6

Purpose: Although previous studies on the screw-home movement (SHM) for autopsy specimen and walking of living persons conduc­ted, the possibility of acquiring SHM based on inertial measurement units received little attention. This study aimed to investigate the possibility of measuring SHM for the non-weighted bearing using a micro-electro-mechanical system-based wearable motion capture system (MEMSS). Methods: MEMSS and camera-based motion analysis systems were used to obtain kinematic data of the knee joint. The knee joint moved from the flexion position to a fully extended position and then back to the start point. The coefficient of multiple correlation and the difference in the range of motion were used to assess the waveform similarity in the movement measured by two measurement sys­tems. Results: The waveform similarity in the sagittal plane was excellent and the in the transverse plane was good. Significant differences were found in the sagittal plane between the two systems (p< 0.05). However, there was no significant difference in the transverse plane between the two systems (p >0.05). Conclusion: The SHM during the passive motion without muscle contraction in the non-weighted bearing appeared in the entire range. We thought that the MEMSS could be easily applied to the acquisition of biomechanical data on the knee related to physical therapy.

마이크로 스크류 성형해석을 위한 소재의 유동응력 모델 고찰

송전한(J. H. Song),이근안(G. A. Lee),이혜진(H. J. Lee),이낙규(N. K. Lee),박기동(K. D. Park),이형욱(H. W. Lee) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.10

This paper deals with the typical evaluation of hardening models of ANSI410 stainless steels for the thread rolling simulation of micro-screws. Comparison tests of the material were firstly carried out in order to obtain the stress-strain curves. The curves were then interpolated with Ludwick equation and Hockett-Sherby equation. Interpolation results indicates that Hockett-Sherby model provide relatively well description for the hardening behavior of ANSI 410 steel. Both simulations and experiments were finally conducted to verity the hardening equation. The results fully demonstrate that Hockett-Sherby model is more suitable for the FE simulation of thread rolling process for ANSI 410 micro-screws.

PDMS-based Screw-wall Micro uidic Channel Forming a Turbulent Flow at Low Reynold Number

김준민,임재관,이태린,박상윤 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.1

A mixture of reactants in a PDMS(Polydimethylsiloxane)-based microfluidic channel is a very important factor. A mixture of the fluid in a microfluidic channel is frequently achieved by using some special structure such as grooves or form by inducing a high rate flow that results in a high Reynold number (over 24943 ≫ 2000). However, these methods are accompanied by a complicated procedure like lithography or a special attachment protocol between PDMS and glass. In this study, we introduce a PDMS-based screw-wall microfluidic channel (SMC) as a functionalized channel. The SMC can be developed using a simple protocol and skipping some complicated procedures. Nevertheless, a turbulent flow showing the same mixing performance at low flow rate can be formed. The turbulent flow in the SMC is supported by a computational simulation and is observed by using a mixture of red ink and blue ink under a microscope. Furthermore, its effectiveness for commercial application is confirmed with the synthesis of nanoparticles. The dispersion coefficient (DR) is suggested in a computational simulation and is calculated for three different ratios of the screw thread diameter to the pipe line diameter. This shows that the more effective the mixture by turbulent flow in the SMC is, the nearer to 1 the ratio is. In experiments, a comparison study of a SMC and a plain wall microchannel shows clear differences in the mixtures performance. Finally, nanoparticles are synthesized for 5 different SMCs with pipe line diameters of 120, 170, 200, 500, and 1000 um and a single-peaked distribution for the sizes of the nanoparticles is observed when a 120 um SMC is applied. These results prove that the SMC developed by using our suggesting simple protocol can form a turbulent flow at low flow rate and is good enough to be used as a mixer.

An Investigation of Thread Rolling Characteristics of Titanium Micro-Screws according to Die Design Parameters

이지은(Ji Eun Lee),김종봉(Jong-Bong Kim),박근(Keun Park) Korean Society for Precision Engineering 2017 한국정밀공학회지 Vol.34 No.2

Detection and Quantification of Screw-Home Movement Using Nine-Axis Inertial Sensors

Jeon, Jeong Woo,Lee, Dong Yeop,Yu, Jae Ho,Kim, Jin Seop,Hong, Jiheon The Korean Society of Physical Therapy 2019 대한물리치료학회지 Vol.31 No.6

Purpose: Although previous studies on the screw-home movement (SHM) for autopsy specimen and walking of living persons conducted, the possibility of acquiring SHM based on inertial measurement units received little attention. This study aimed to investigate the possibility of measuring SHM for the non-weighted bearing using a micro-electro-mechanical system-based wearable motion capture system (MEMSS). Methods: MEMSS and camera-based motion analysis systems were used to obtain kinematic data of the knee joint. The knee joint moved from the flexion position to a fully extended position and then back to the start point. The coefficient of multiple correlation and the difference in the range of motion were used to assess the waveform similarity in the movement measured by two measurement systems. Results: The waveform similarity in the sagittal plane was excellent and the in the transverse plane was good. Significant differences were found in the sagittal plane between the two systems (p<0.05). However, there was no significant difference in the transverse plane between the two systems (p>0.05). Conclusion: The SHM during the passive motion without muscle contraction in the non-weighted bearing appeared in the entire range. We thought that the MEMSS could be easily applied to the acquisition of biomechanical data on the knee related to physical therapy.

Detection and Quantification of Screw-Home Movement Using Nine-Axis Inertial Sensors

전정우,이동엽,유재호,김진섭,홍지헌 대한물리치료학회 2019 대한물리치료학회지 Vol.31 No.6

Purpose: Although previous studies on the screw-home movement (SHM) for autopsy specimen and walking of living persons conducted, the possibility of acquiring SHM based on inertial measurement units received little attention. This study aimed to investigate the possibility of measuring SHM for the non-weighted bearing using a micro-electro-mechanical system-based wearable motion capture system (MEMSS). Methods: MEMSS and camera-based motion analysis systems were used to obtain kinematic data of the knee joint. The knee joint moved from the flexion position to a fully extended position and then back to the start point. The coefficient of multiple correlation and the difference in the range of motion were used to assess the waveform similarity in the movement measured by two measurement systems. Results: The waveform similarity in the sagittal plane was excellent and the in the transverse plane was good. Significant differences were found in the sagittal plane between the two systems (p<0.05). However, there was no significant difference in the transverse plane between the two systems (p>0.05). Conclusion: The SHM during the passive motion without muscle contraction in the non-weighted bearing appeared in the entire range. We thought that the MEMSS could be easily applied to the acquisition of biomechanical data on the knee related to physical therapy.

SWCH18A 와 SUS XM7 을 적용한 초소형 나사제작 및 물성분석에 관한 연구

나승우(Seung-Woo Ra),김인락(In-Rak Kim),황성택(Sung Tack Hwang) 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.9

체결부품의 사이즈가 작아질수록 실제 접합부의 면적이 줄어들기 때문에 체결력은 감소한다. 이러한 체결부품의 체결력을 결정하는 요소는 소재(Material), 구조(Geometry), 마찰(Friction)이 있다. 본 연구에서는 체결부품의 사이즈가 줄어들면서 체결력을 향상시킬 수 있는 방법 중의 하나인 소재 변경에 대하여 연구하였다. SWCH18A 와 SUS XM7 을 적용하여 초소형 나사를 제작하였으며, 3 차원 치수 측정을 통하여 피치정밀도와 두께정밀도를 측정하였다. 비커스 경도 측정을 통하여 나사가 외부의 힘에 의해 변형에 대한 저항력을 분석하였다. 또한 파단토크 시험과 SEM 을 이용한 파단면 분석을 통해 파단특성을 분석한다. As micro screws feature reduced screw lengths and pitches, the resulting clamping force diminishes because of the reduced length of the actual joints. The elements of the clamping force are material, geometry, and friction. We studied the shrinking size of the screw and the methods to improve the clamping force by changing the material. We developed a micro screw using SWCH18A and SUS XM7 materials, and obtained the precision and thickness of the pitch through three-dimensional measurement. We also measured the external resistance of the micro screw by applying the Vicker"s hardness test and conducted a break surface analysis using a break torque test and SEM for obtaining the break characteristics.