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김재실(Chae Sil Kim),이재훈(Jae Hoon Lee) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.6
The role of dynamic behavior of operating rotor system in rotor design may or may not be evaluated under the impact of an external force such as earthquake. This article reports the result of an experimental study to resolve the dilemma. First, a sine weep test was performed to determine the first natural frequency of a Jeffcott rotor and compared with the ANSYS mode analysis demonstrating the reliability of experimental tests. The operating rotor vibrations were measured under the impact of sinusoidal forces at several frequencies, generated by the MTS vibration exciter. The experimental data suggest the need for a rotor design considering the dynamic behavior of the operating rotor under exciting external forces.
복합공구대 비틀림계 진동에 대한 기어 맞물림 강성의 영향에 관한 연구
김재실(Chae-sil Kim),김수태(Soo-Tae Kim),조수용(Soo-Yong Cho),정훈형(Hoon-Hyung Jung) 한국기계가공학회 2009 한국기계가공학회지 Vol.8 No.2
This paper describes mathematical models of the torsional geared driving system for the indexing path and the mill driving path in a mill turret. The eigenvalue analysis for the models is conducted both with and without the gear contact stiffnesses. The natural frequency leads to the effect of gear contact stiffnesses on the vibration of torsional geared systems in a mill turret. It is necessary to analyze eigenvalues of the complex geared torsional system in order to prevent the unexpected vibrations.
A Study on the Structural Integrity of an Auxiliary Feed Water Pump in a Nuclear Power Plant
Chae-Sil Kim(김재실),Bang-Hyun Cho(조방현) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.3
The auxiliary-feed-water pump (AFWP) used to supply water during a station black out situation at nuclear power plants should meet the seismic qualification regulations stipulated in IEEE Std 323 and 344, so as to withstand earthquakes or dangerous situations. Here, we establish a model for the estimation of the structural integrity of this type of pump. If the natural frequency that results from a modal analysis is less than 33 Hz, we adopt a dynamic analysis, instead of a static analysis. A dynamic analysis was carried out taking into consideration seismic conditions such as the floor response spectra (FRS), an operation-base earthquake (OBE), and a safe-shutdown earthquake (SSE). Finally, an analytical estimation of the structural integrity of an AFWP is made through a comparison of calculated values and allowable values. If the result is less than the allowable stress, the pump is deemed to have good structural integrity. In addition, future studies will involve a stability check for rotor accidents that may occur during the operation of the pump.
Chae-Sil Kim(김재실),Hoon-Hyung Jung(정훈형),Bong-Kwan Park(박봉관) 한국기계가공학회 2013 한국기계가공학회지 Vol.12 No.6
High speed rotor systems with magnetic bearings have been the subject of much research in recent years due to the potential for active vibration control. In this thesis, optimal design was conducted for an 8-pole heteropolar magnetic bearing used in the flexible rotor of a turbo blower. In connection with bearing stiffness, this optimal design process was conducted using a genetic algorithm(GA), which is based on natural selection and genetics. The maximum stiffness of the magnetic bearing-rotor was found by considering the critical speeds of the flexible rotor. As a result, the magnetic bearings were optimized to have maximum stiffness.
복합공구대용 B축 회전테이블 웜 기어의 정/동적 안정성 및 피로에 관한 연구
김재실(Chae-sil Kim),강승희(Seung-hee Kang) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.5
Highly functional mill turrets have been developed and continuously improved to shorten the manufacturing time and enable multiple uses. Among these, a mill turret with B-axis rotary table was developed. The B-axis rotary table should be evaluated for structural integrity. Moreover, its worm and worm gear for transmitting power should be able to endure fatigue damage. Therefore, this article presents a structural analysis of this type of B-axis rotary table and confirms its static stability by comparing the stress results to the allowable stress levels. Next, the dynamic stability of the rotary table was investigated via a mode analysis and a harmonic analysis in a range determined by the results of a modal analysis. Finally, a worm gear set, the main part that drives the rotary table, is analyzed for fatigue and to estimate its lifetime. The results of the fatigue analysis allowed a prediction of the life of the worm gear set. The analytical results show that the B-axis rotary table has good structural integrity.
김재실(Chae Sil Kim),신민재(Min Jae Shin),금창민(Chang Min Keum),김재민(Jae Min Kim),최현오(Hun Oh Choi) Korean Society for Precision Engineering 2016 한국정밀공학회지 Vol.33 No.8
The article describes the determination of the dynamic stability for an observation antenna, considering the rotational speed by the payload driving motor. A finite element model of the observation antenna was made using the solid and beam elements. The connecting parts between the solid and the beam was adequately coupled. The boundary conditions were made by restriction of the degree of freedoms in the supporting points. With the comparison between the modal analysis results and the rotating speed of the payload driving motor, no resonance for the structure of antenna was identified and first natural frequency was determined under 33 Hz (Seismic Cut-Off Frequency). Therefore, the dynamic stability of the antenna was confirmed by the comparism between the seismic safety criterion and the stress results of the dynamic analysis applied the loading conditions and required response spectrum (RRS).
Study of the Dynamic Characteristics of a High-Pressure Labyrinth Seal Considering Rotor Whirling
김재실(Chae Sil Kim),이경진(Kyung Jin Lee),신민재(Min Jae Shin) Korean Society for Precision Engineering 2015 한국정밀공학회지 Vol.32 No.8
This article describes the calculation procedure for the dynamic characteristics of a high-pressure labyrinth seal wherein the friction force and rotor whirling force are considered; SFCP, the commercial code developed by Lee and two colleagues, is used in the procedure. The simulation results were reviewed in comparison to those of the experiments provided by Benckert; additionally, the SFCP simulation results were verified using the CFD analysis presented by Toshio Hirano. This calculation procedure may therefore be applied to the dynamic characteristics of the labyrinth seals of high-pressure turbo machinery.
Wire Rope Isolator 마운팅 수동 조작 패널의 진동 저감
김재실(Chae-Sil Kim),김동일(Dong-Il Kim),허종대(Jong-Dae Heo),황재덕(Jae-Deok Hwang) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.6
This paper reviews a finite element model of a wire rope isolator (WRI) via an experimental comparison test. A local operation panel (LOP) mounted on a WRI is modeled using a finite element method. Mode analyses and harmonic analyses are conducted while varying of the thickness of the rope for the WRI. A feasible WRI can be selected considering the reduction of the vibration and the total weight of the LOP system.