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심우성(Shim W.S.),김재훈(Kim J.H.),이영신(Lee Y.S.),차기업(Cha K.U.),홍석균(Hong S.K.) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Thick-walled cylinders, such as a cannon or nuclear reactor, are autofrettaged to induce advantageous residual stresses into pressure vessels and to increase operating pressure and the fatigue lifetimes. As the autofrettage level increases, the magnitude of compressive residual stress at the bore also increases. However, the Bauschinger effect reduces the compressive residual stresses as a result of prior tensile plastic strain, and decreases the beneficial autofrettage effect. The purpose of the present paper is to predict the accurate residual stress of SNCM8 high strength steel using the Kendall model which was adopted by ASME Code. The uniaxial Bauscinger effect test was performed to decide BEF, then this constant was used in calculation. There were some differences between theoretical solution and modified solution.
임승철,김기갑,심정수,길성진,이건하,차기업,조창기,홍석균,Lim, S.,Kim, K.K.,Shim, J.S.,Kil, S.J.,Lee, G.H.,Cha, G.U.,Cho, C.K.,Hong, S.K. 한국군사과학기술학회 2006 한국군사과학기술학회지 Vol.9 No.1
Lately, there exist growing demands for the use of CTAs(Cased Telescoped Ammunitions) to increase the firepower of mid-calibre automatic guns despite spatial limitations of armament. In this paper, for automatic CTA guns a rotating chamber mechanism is designed based on parallel index concept. Via dynamic simulations it proves capable of smooth operation even at as high a firing rate as 200spm. Subsequently, motor controllers are synthesized to drive the chamber at any constant speed and also to control positions in the presence of large disturbances caused by the intermittently-rotating load. It is remarkable that we successfully adopted a disturbance observer to treat disturbances only with a moderate bandwidth of the closed-loop system.
간헐 회전식 약실을 적응한 자동포 시스템의 디지털 제어
임승철,김기갑,심정수,길성진,김홍철,이건하,차기업,조창기,홍석균,Lim, S.C.,Kim, K.K.,Shim, J.S.,Kil, S.J.,Kim, H.C.,Lee, G.H.,Cha, G.U.,Cho, C.K.,Hong, S.K. 한국군사과학기술학회 2007 한국군사과학기술학회지 Vol.10 No.2
Lately, there exist growing demands to increase the firepower of mid-calibre automatic guns despite spatial limitations of armament. In this context, ammunitions of simple cylindrical shape are considered so advantageous that associated automatic guns are under development incorporating an intermittently rotating chamber mechanism. In this paper, relevant subsystems for such guns are to be described, and a digital controller to automate the entire system as well. Via dynamic simulations it proves to function well being able to drive the chamber at any constant speed up to 200spm, which is merely limited by the recoil performance. It is remarkable that the system synchronization idea in use is applicable to any other multi-actuator systems that should operate on the basis of event rather than time.
자긴가공된 SCM440 고강도강의 잔류응력 및 미세구조 분석에 관한 연구
김재훈(Kim J.H.),심우성(Shim W.S),이영신(Lee. Y.S.),차기업(Cha K.U.),홍석균(Hong. S.K.) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Thick-walled cylinders, such as a cannon or nuclear reactor, are autofrettaged to induce advantageous residual stresses into pressure vessels and to increase operating pressure and the fatigue lifetimes. As the autofrettage level increases, the magnitude of compressive residual stress at the bore also increases. The purpose of the present paper is to predict the accurate residual stress of SCM440 high strength steel using the Kendall model which was adopted by ASME Code. Hydraulic pressure process was applied and thick-walled cylinders were autofrettaged up to 30% overstrain levels. Electro polishing was performed to get more accurate data. Residual stresses were measured by X-ray diffraction method. The autofrettaged surface which was plastically deformed analyzed using a scanning electron microscope(SEM). Although there were some differences in measured residual stress and numerical, there is a tendency to agree.
Ti-Ni-X (X = Cu, Al) 형상기억합금의 의탄성 및 내식성에 관한 연구
천병선,한철호,이형란,홍석균 대한금속재료학회(대한금속학회) 1990 대한금속·재료학회지 Vol.28 No.6
Pseudoelasticity behaviour and passivetion treatment on the shape memory alloys are known to have a great deal of influence on the stability of transformation temperature, shape recovery and improvement of corrosion resistance characteristics in their practical applications. The present work was aimed to examine the pseudoelasticity characteristics by tensile test, and corrosion resistance characteristics by corrosion test in Ti-Ni-X(X-Al, Cu) alloys with/ without passivation treatment. The results of this study are as follows, 1. The results of tensile test for Ti-Ni-X(X-Al, Cu) alloys show that the shape recovery is nearly perfect in martensite state and critical stress for slip is increased with increasing strain. Also, the pseudoelasticity behaviour appears in Ti_(50.0)Ni_(40.0)Cu_(10.0) alloy by unloading at temperature above Af and Ti_(50.0)Ni_(49.0)Al_(10.0) alloy by cold working over 25%. 2. The results of the anodic polarization corrosion test show that the corrosion resistance characteristics of Ti-Ni based alloys can be increased by application of passivation treatment and Ti-Ni-X(X=Al, Cu) alloys has better corrosion resistance characteristics than Ti-Ni equiatomic composition alloy.