탄성사 분사기계의 트래버스 캠 해석

최성렬,이종옹,신재균,Choi, Sung-Ryul,Lee, Jong-Ong,Shin, Jae-Kyun 한국섬유공학회 2005 한국섬유공학회지 Vol.42 No.6

The traverse cam system in a spandex yarn splitting machine is an element to wind the splitted yarn plainly on a winding drum, which is equipped mainly with a differential gear and four-bar linkages. As the cam system is working under a high speed, the dynamic balancing and precise kinematic mechanism is important to enhance working efficiency and reduce vibration problems. In this study, a method to evaluate the mechanism precision and dynamic balance is suggested. Applying this method to the developed traverse cam system showed this method can be effectively used to develop estimate the cam system in the design processes before manufacturing.

횡등방 압전재료의 면외하중 모서리 균열에 대한 그린함수

최성렬(Sung Ryul Choi) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.1

Surface edge crack in transversely isotropic piezoelectric material is analyzed. The concentrated antiplane mechanical and inplane electrical loadings are applied to an arbitrary point of the surface, where the impermeable crack boundary condition is imposed. Using Mellin transform the problem is formulated, from which Wiener-Hopf equations are derived. By solving the equations the solution is obtained in a closed form. Mechanical and electric intensity factors and energy release rate are obtained and discussed. This problem could be used as a Green's function to generate the solutions of other problems with the same geometry but of different loading conditions.

전기적 혼합조건하의 이종 압전재료에 대한 면외 계면 쐐기균열

최성렬(Sung Ryul Choi),정일섭(Ilsup Chung) 대한기계학회 2022 大韓機械學會論文集A Vol.46 No.4

횡등방 이종재료에 형성된 쐐기 계면균열문제을 해석하였다. 두 재료의 상하 표면의 임의 점에 면외 집중하중과 면내 전기적 하중이 각각 작용하고 있고, 계면균열면은 전기적으로 혼합조건이라고 가정하였다. 혼합조건은 전기적 침투 및 절연조건이 균열면을 따라 일정비율을 유지하며 작용하는 조건을 말한다. 침투조건 및 절연조건에 대한 문제를 각각 해석하고 그 얻은 결과를 토대로 중첩함으로써 혼합조건에 대한 해를 얻었다. Mellin 변환을 사용하여 침투 및 절연문제를 각각 수식화하고, Wiener-Hopf식을 유도하였다. 이 식의 해를 구하여 적용함으로써 균열선단에 대한 점근해를 얻었다. 임의 균열길이나 압전재료 상수 등에 대해서도 적용이 가능한 4개 균열선단의 강도계수의 엄밀해를 구하였다. 강도계수는 침투 및 절연조건에 대하여 다르게 표현되었다. 이를 가지고 중첩함으로서 혼합정도에 따른 응력강도계수와 에너지방출률을 수치적으로 계산하여 알아보았다. 혼합균열문제의 에너지 방출률을 계산한 결과 침투와 절연문제의 해는 각각 상한값 및 하한값이 됨을 보였다. 이 해는 임의로 분포하는 전기기계하중문제에 대한 기본 해로 사용될 수 있다. An interfacial wedge crack in transversely isotropic piezoelectric bi-material is analyzed. An antiplane concentrated force and an in-plane electrical load are applied on the inclined outer surface of each material. The electrically mixed condition is assumed on the interfacial crack, implying a uniform ratio of electrical permeability and impermeability along the crack face. Separate solutions for the permeability and impermeability conditions can be superposed to obtain the solution for the mixed condition. A Wiener-Hopf equation is formulated using the Mellin transform and is solved to yield an asymptotic solution for the crack tip. The four kinds of intensity factors and energy release rate can be calculated for arbitrary crack length and piezoelectric properties. Notably, the permeability and impermeability conditions correspond to the upper and lower limit cases of the energy release rate, respectively.

압전재료에 대한 면외하중하의 모서리 경사 균열

최성렬(Sung Ryul Choi),사종엽(Jong Youb Sah),정재택(Jae Tack Jeong) 대한기계학회 2015 大韓機械學會論文集A Vol.39 No.6

횡등방성 압전재료에 대한 모서리경사균열 문제를 해석하였다. 두 기계적 집중 면외하중과 전기적 집중 면내하중이 표면과 균열면에 각각 작용하고, 균열면은 절연균열면이다. 일반화된 변위벡터를 도입하고 Mellin 변환을 사용하여 문제를 수식화하고, 이로부터 Wiener-Hopf 식을 유도하였다. 이식을 풀므로써 폐형으로 주어지는 해를 얻었다. 임의의 균열길이나 경사각에 대해서도 적용이 되는 응력 및 전기변위 강도계수와 에너지 방출율을 구하였다. 이 해는 중첩에 의하여 임의로 분포하는 전기기계하중 문제에 대한 해를 제공하는 기본해로 사용될 수 있다. The occurrence of an inclined edge crack in transversely piezoelectric material is analyzed. Concentrated antiplane mechanical and inplane electrical loads are applied at the boundary and crack surface, respectively. The crack surfaces are assumed to be impermeable to the electric field. Using the Mellin transform with the introduction of a generalized displacement vector, the problem is formulated, and the Wiener?Hopf equation is derived. By solving the equation, the solution is obtained in a closed form. The intensity factors of the stress, the electric displacement, and the energy release rate are obtained for any crack length and inclination angle. These solutions can be used as fundamental solutions and can be superimposed to represent any arbitrary electromechanical loading.

거베라 품종 특성 및 품질 차이

최성렬(Sung Ryul Choi),김영아(Young A Kim),권오근(Oh Keun Kweon),정향영(Hyang Young Joung) 한국원예학회 2003 한국원예학회 학술발표요지 Vol.2003 No.5

면외변형하의 압전재료에 대한 침투 쐐기균열

최성렬(Sung Ryul Choi),박재학(Jai Hak Park) 대한기계학회 2015 大韓機械學會論文集A Vol.39 No.9

횡등방성 압전재료에 기하학적 비대칭인 쐐기균열문제를 해석하였다. 기계적 집중면외하중과 전기적 집중 면내하중이 쐐기표면 점에 작용하고 있고, 반면에 균열면 한점에는 기계적 집중하중만 작용한다. 균열면은 침투형 얇은 슬릿으로 가정하여, 전기변위의 수직성분 및 전위가 균열면을 가로질러 연속으로 두었다. Mellin 변환을 사용하여 문제를 수식화하고, Wiener-Hopf 식을 유도하였다. 이 식을 풀므로써 폐형으로 주어지는 해를 얻었다. 임의 균열길이나 경사각, 쐐기각에 대해서도 적용이 가능한 응력 및 전기변위 강도계수를 구하였다. 장의 강도계수들은 전기적 하중에는 무관하고, 전기변위강도계수는 응력강도계수만의 함수로 표현되었다. 전기장 강도계수는 영으로 계산되었다. 또한 에너지방출률을 얻었다. 이 해는 중첩에 의하여 임의로 분포하는 전기기계하중문제에 대한 해를 제공하는 기본해로 사용될 수 있다. In this study, we analyze the problem of wedge cracks, which are geometrically unsymmetrical in transversely piezoelectric materials. A single concentrated antiplane mechanical load and inplane electrical load are applied at the point of the wedge surface, while one concentrated antiplane load is applied at the crack surface. The crack surfaces are considered as permeable thin slits, where both the normal component of electric displacement and the electric potential are assumed to be continuous across these slits. Using Mellin transform method, the problem is formulated and the Wiener-Hopf equation is derived. By solving the equation, the solution is obtained in a closed form. The intensity factors of the stress and the electric displacement are obtained for any crack length as well as inclined and wedge angles. Based on the results, the intensity factors are independent of the applied electric loads. The electric displacement intensity factor is always dependent on that of stress intensity factor, while the electric field intensity factor is zero. In addition, the energy release rate is computed. These solutions can be used as fundamental solutions which can be superposed to arbitrary electromechanical loadings.

플립 칩의 기하학적 형상과 구성재료의 변화에 따른 효과

권용수(Yong-Su Kwon),최성렬(Sung-Ryul Choi) 한국산업융합학회 2000 한국산업융합학회 논문집 Vol.3 No.1

Multichip packages are comprised of dissimilar materials which expand at different rates on heating. The differential expansion must be accommodated by the various structural elements of the package. A types of heat exposures occur operation cycles. This study presents a finite element analysis simulation of flip-chip among multichip. The effects of geometries and material properties on the reliability were estimated during the analysis of temperature and thermal stress of flip-chip. From the results, it could be obtained that the more significant parameters to the reliability of flip-chip arc chip power cycle, heat convection and height of solder bump.<br/> <br/> <br/>

다꾸찌방법을 사용한 여러변수들이 패키지균열에 미치는 신뢰도 평가

권용수,박상선,박재완,채영석,최성렬,Kwon, Yong-Su,Park, Sang-Sun,Park, Jae-Wan,Chai, Young-Suck,Choi, Sung-Ryul 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.6

Package crack caused by the soldering process in the surface mounting plastic package is evaluated by applying the maximum energy release rate criterion. It could be shown that the crack propagation from the lower edge of the ie pad is easily occurred at the maximum temperature during the soldering process, where the pressure acting on the crack surface is assumed by the saturated vapor pressure at maximum temperature. The package crack formation depends on various parameters such as chip size, relative thickness, material properties, the moisture content and soldering temperature etc. The quantitative measure of the effects of the parameters could be easily obtained by using the taguchi's method which requires only a few kinds of combinations with such parameters. From the results, it could be obtained that the more significant parameters to effect the package reliability are the orders of Young's modulus, die pad size, down set, chip thickness and maximum soldering temperature.

상이한 직교이방성 띠판에 대한 면외변형 하의 반무한 등속 평행균열에서의 응력확대계수

박재완,권용수,정재택,최성렬,Park, Jae-Wan,Kwon, Yong-Su,Jeong, Jae-Tack,Choi, Sung-Ryul 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.3

Stress intensity factor of semi-infinite parallel crack propagation with constant velocity in dissimilar orthotropic strip under out-of-plane clamped desplacement is investigated. Using Fourier integral transforms the boundary value problem is derived by a pair of dual integral equation and finally reduced to a single Wiener-Hopf equation. By applying Wiener-Hopf technique the equation is solved. Applying this result the asymptotic stress fields near the crack tip are determined, from which the stress intensity factor is obtained in closed form. The more the ratio of anisotropy or the ratio of bi-material shear modulus increase in the main material including the crack, the more the stress intensity factor increases. Discontinuity in the stress intensity factor is found as the parallel crack approaches the interface. In special case, the results of isotropic materials agree well with those by the previous researchers.

x-ray 및 밀도 측정에 의한 거베라 줄기의 공동 관찰

김영아(Young A Kim),최성렬(Sung Ryul Choi),신학기(Hak Ki Shin),최동수(Dong Su Choi) 한국원예학회 2005 한국원예학회 학술발표요지 Vol.2005 No.10