http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
권동일(Dongil Kwon),이경우(Kyung Woo Lee),김성훈(Sung-Hoon Kim),김주영(Ju-Young Kim),이윤희(Yun-Hee Lee) 한국정밀공학회 2005 한국정밀공학회 학술발표대회 논문집 Vol.2005 No.10월
The nanoindentation technique is widely used to investigate the mechanical properties of nano-microscale materials. The nanoindentation method for assessing mechanical properties at low loads and shallow depths is already well established for the characterization of thin films as well as bulk materials. In this study, we evaluated residual stress in DLC and Au thin films usign nanoindentation technique with a new stress-relaxation model. Moreover, We suggest a composite hardness equation and quantify the magnitude of hardness increase by using an equation based on the interface hardness and the interface thickness, derived by comparing results derived from this equation and those determined in nanoindentation tests. Finally, We present an indentation size effect (ISE) model that extends the available contact depth for ISE application down to several tens of nanometers by considering the tip bluntness effect.
강구조물에 대한 현장에서의 비파괴적 인장물성 평가 기술 개발
손동일 ( Son Dongil ),최열 ( Choi Yeol ),장재일 ( Jang Jae-il ),권동일 ( Kwon Dongil ) 한국구조물진단유지관리공학회 2001 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.5 No.1
A newly developed Advanced Indentation System (AIS), which is a portable and nondestructive system for evaluating tensile properties, was used to measure stress-strain behavior of steel structure. For all test materials and conditions, the AIS-derived results were in good agreement with those from conventional standard test method. Furthermore, the nondestructive AIS test results rigorously indicated the various levels of degradation of materials. Examples of the test results are given and potential applications of the AIS to assess the integrity of aging structures are briefly discussed.
연속압입시험법을 이용한 원전구조물의 잔류응력 평가를 위한 접촉깊이의 보정
김영천,강승균,안희준,김광호,권동일,Kim, Young-Cheon,Kang, Seung-Kyun,Ahn, Hee-Jun,Kim, Kwang-Ho,Kwon, Dongil 한국압력기기공학회 2011 한국압력기기공학회 논문집 Vol.7 No.1
Residual stress is the key parameter for reliability and lifetime assessment because it can reduce the fatigue strength and fracture properties of industrial structures. Recently, instrumented indentation testing (IIT) has been widely used for evaluating it, since it does not need specific specimen and time-consuming procedure. However, conventional Oliver-Pharr method, which is used for calibrating contact depth to analyze indentation load-depth curve, cannot estimate plastic pile-up between indenter and surface of specimen. Here, we introduce f parameter which is the ratio of contact depth and maximum depth, to consider pile-up height. And, its application for evaluating residual stress of weldment is introduced.
전은채(Jeon Eun-chae),권동일(Kwon Dongil),박주승(Park Joo-Seung) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
Ithasbeenshownthatadvancedindentationtechniquecanevaluatetensilepropertiesfromtheload-depth<br/> curveswithoutopticalobservationbymanyresearches.Whentheexperimentsareperformed,itis,however,<br/> verydifficulttodeterminethevaluesofvariousexperimentalvariations.Theireffectsontheresultswere<br/> seldomstudied.Amongthevariations,themaximumdepthratio,theindenterradius,thenumberofunloads<br/> andtheunloadingratioareveryimportant.UsingTaguchimethod,whichisoneoftheDOE(designof<br/> experiment),westudiedtheireffectsquantitatively.Theload-depthcurveswereanalyzedbythemethod<br/> toderivetensileproperties.Todeterminetheoptimumvaluesofthevariations,theSN(signal-to-noise)values<br/> werecalculated.ForeachparameterthevaluewhoseSNvalueismaximumisdeterminedastheoptimum<br/> one.Thetensilepropertiesfromtheload-depthcurveswiththeoptimumvaluesshowedbetterconsistency<br/> thanoneswithothervalues.
김동원(Dong-Won Kim),권동일(Dongil Kwon) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
In the process of manufacturing and operation of electronic components and in-field real systems in the<br/> industrial fields, the residual stress is evolved in and on the systems by the irregular elastic/plastic stress<br/> distribution. The evaluation of residual stress has always been a matter and interest of concern between many<br/> mechanical engineering researchers. Therefore we have studied the surface residual stress mapping around<br/> indented Cu by ESPI (Electronic Speckle Pattern Interferometry). ESPI can measure nondestructively the<br/> in-situ displacement fields with highly advanced resolution in displacements (~10^-2㎛) on the basis of the interferometry principle. We have also manufactured the optical vacuum thermal chamber with optical window<br/> so as to obtain the in-situ fringe patterns in annealing the specimens. By using above optical devices, we<br/> defined the free residual stress state by determining full annealing moment of specimens by the in-situ<br/> displacement measuring ability of ESPI. And we evaluated the relaxed stress based on the thermo-elastic<br/> theory. As a result, we mapped the residual stress field of the whole detected area.<br/> <br/> <br/> <br/>
이정석(Jung-Suk Lee),권동일(Dongil Kwon),김광호(Kwang-ho Kim),서양원(Yang Won Seo) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.8
Apparent mechanical properties in structural components can be different from the initially designed values due to the formation of the residual stress in metal forming and welding. Therefore, the evaluation of residual stress has great importance in the reliability diagnosis of structural components. A nondestructive continuous indentation technique has been proposed to evaluate various strength concerning mechanical properties from the analysis of load-depth curve. In this study, quantitative residual stress estimation on API X65 welded joints for natural gas pipeline was performed by analyzing the variation of indentation loading curve by residual stress through a new proposed theoretical model. The residual stress from the indentation method was compared with that from the saw-cutting method.
연속압입 시험기법을 이용한 석유화학설비 경년손상의 새로운 평가변수 고찰
장재일,최열,손동일,이윤희,권동일,김정태,Jang, Jae-Il,Choi, Yeol,Son, Dongil,Lee, Yun-Hee,Kwon, Dongil,Kim, Jeoung-Tae 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.5
Newly developed continuous indentation technique has made nondestructive assessment of tensile properties possible. The present study was undertaken to determine new parameters for indicating time-dependent material degradation of petro-chemical plant. Continuous indentation tests were performed for Cr-Ni steel and Cr-Mo steel which are widely used as facilities of petro-chemical plant. From the results, it was found that yield strength and tensile strength cannot be used as general degradation parameters because the changes in the strengths with aging time didn't show any tendency. On the other hand, work hardening exponent and yield ratio showed consistent tendency with increasing aging time. Therefore, nam attention of this work was paid on them as new degradation parameters, and the in-field applicability of the parameters was evaluated and discussed.