마이크로터널링 기술의 현재와 미래① -마이크로터널링 기술의 소개-

최명진,이창호,김명모 한국지반공학회 2000 지반 : 한국지반공학회지 Vol.16 No.1

마이크로터널링 기술의 현재와 미래\circled1

최명진,이창호,김명모 한국지반공학회 2000 지반 : 한국지반공학회지 Vol.16 No.1

초기 인장력을 고려한 파이프계의 자유진동 시뮬레이션

최명진 한국시뮬레이션학회 1998 한국시뮬레이션학회 논문지 Vol.7 No.2

Using finite elements, a simulation is prformed for the pipe systems to investigate free vibrational characteristics, that is natural frequencies, considering the intial tension due to the velocity and the pressure of the inside fluid flow. To confirm the program developed in this study, the results are compared with the results of commercial software ANSYS. When the initial tension is neglected in curved pipes, the natural frequencies are reduced as flow velocity increases, and the rapid decreases of the natural frequencies took place. However, when the initial tension is taken into account, the natural frequencies are not changed with the change of the flow velocity. In free vibrational simulation of pipe systems, it is necessary to calculate the initial state force due to the velocity and the pressure of the fluid flow from the equilibrium first, then the force should be included in the equation of motion of the systems to get more accurate natural frequencies.

시뮬레이션에 의한 유체 유동 굴곡파이프의 지지점 변화에 따른 고유 진동수 고찰

최명진 한국시뮬레이션학회 1998 한국시뮬레이션학회 논문지 Vol.7 No.2

A simulation is performed to investigate the effect of the pipe supports on the change of the natural frequencies of curved pipe systems containing fluid flow, for different elbow angles and geometry of the pipe systems. Based upon the Hamilton's principle, the equations of motions are derived, and the finite element equation is constructed to solve the corresponding eigenvalue problem. The angles of elbows do not affect the change of the fundamental natural frequency, but affect the change of the third or higher natural frequencies. Without any support, the change of the fundamental natural frequency due to the geometric change is smaller than the change of the second or higher natural frequencies. The more curve parts exist in the pipe system, the less change of lower frequency range, compared with the change of higher frequency range, is observed. Spring supports can be used to reduce the fundamental natural frequency, without change of the second or higher natural frequencies. To avoid resonance, which is critically dangerous from the view point of structural dynamics, the mechanical properties such as stiffness or the location of pipe supports are need to be changed to isolate the natural frequencies from the frequency range of dominant vibration modes.

고해상도 위성 영상을 위한 MTF 보상 기술

최명진,서두천,송정헌,양지연,이동한,정호령,임효숙 한국항공우주학회 2008 한국항공우주학회 학술발표회 논문집 Vol.- No.-

지방자치단체 공공시설의 효율적 관리방안에 관한 연구 - 한국과 일본의 정책을 중심으로 -

최명진,동재욱,이화룡 한국교육시설학회 2020 敎育施設 Vol. No.

한국도 대다수의 OECD 국가들처럼 인구 감소 및 인구 구조의 변화가 나타나고 공공시설의 노후화가 도래되고 있으며, 경제의 저성장과 복지 예산의 증대로 공공시설의 유지관리 대한 투자에 한계가 발생할 수 있다. 이 경우 공공시설의 사용상 불편함뿐만 아니라 시설물 파손에 따른 사고 발생으로 이어질 수 있다. 하지만 아직까지 공공시설 관리에 대한 중요성이 인식되지 않아 신설 위주의 정책이 추진되고 있으나 인구감소에 따른 공공시설의 수요 변화는 필연적이다. 한국은 2020년대 후반부터 총인구가 감소하고 같은 행정구역내에서도 읍·면·동간 인구감소의 차이가 많을 것으로 전망되고 있으며, 인구 및 경제 성장기에 건설된 공공 건축물은 향후 20년을 전후로 고령화가 빠르게 진행될 것으로 예상되므로 인구감소 및 고령화 등 인구변화에 따른 공공시설의 수요변화에 대한 관리 정책의 변화가 필요하다. 이에 따라 본 연구에서는 한국의 공공시설의 관리 정책 및 실태를 분석하고 한국보다 먼저 인구변화와 공공시설의 노후화 등을 맞은 일본의 공공시설 관리 정책을 분석하여 공공시설 관리에 대한 시사점을 제시하였다. 일본의 공공시설 관리 정책의 핵심 변화는 신설에서 유지관리로의 정책 전환으로 기존 안전관리와 자산관리 측면에서 공공시설을 관리하는 것으로 나타났다. Like most OECD countries, Korea is experiencing a decline in population and demographic changes, deterioration of public facilities, and limited investment in public facilities maintenance due to low economic growth and increased welfare budgets. In this case, not only the inconvenience of using the public facilities can lead to the occurrence of an accident due to the damage of the facilities. However, as the importance of the management of public facilities has not been recognized yet, new policies are being promoted. Korea is expected to reduce the total population since the late 2020s, and there will be a large difference in population reduction between the cities, towns, and towns within the same administrative districts. Therefore, it is necessary to change the management policy regarding the change in demand of public facilities due to population change such as population decrease and aging. Accordingly, this study analyzes the management policies and actual conditions of public facilities in Korea, and suggests the implications for public facilities management by analyzing Japan's public facilities management policies that faced population change and deterioration of public facilities before Korea. The key change in Japan's public facilities management policy is the transition from new to maintenance, which has managed public facilities in terms of existing safety management and asset management.

시뮬레이션에 의한 유체 유동 파이프 계의 곡관부의 각도 변화에 따른 고유진동수 고찰

최명진,장승호 한국시뮬레이션학회 2001 한국시뮬레이션학회 논문지 Vol.10 No.1

To investigate the natural frequencies of curved piping systems with various elbow angles conveying flow fluid, a simulation is performed considering Initial tension due to the inside fluid. The system is analyzed by finite element method utilizing straight beam element. Elbow part is meshed using 4 elements, and the initial tension is considered by inserting equivalent terms into the stiffness matrix. Without considering the initial tension, the system becomes unstable, that is, the fundamental natural frequency approaches to zero value fast, as the flow velocity reaches critical value. With the initial tension terms, the system becomes stable where there is no abrupt decrease of the fundamental natural frequency. The change rate of the natural frequency with respect to the flow velocity reduces. As elbow angle increases, the system becomes stiffer, then around 150 degrees of the elbow angle the natural frequency has the largest value, the value decreases after the angle of the largest natural frequency. When angle is between 170 degrees and 179 degrees, the natural frequency is very sensitive. This means that small change of angle results in great change of natural frequency, which is expected to be utilized in the control of the natural frequency of the piping system conveying flow fluid.

해석적 방법에 의한 경사진 음관의 음향학적 특성 고찰

최명진,유송민,박흥을 경희대학교 산학협력기술연구원 2004 산학협력기술연구논문집 Vol.10 No.2

To investigate acoustic characteristics of tapered sound-pipes, the throat impedance was evaluated for the straight pipe and conical pipes with varying taper angles. When sound propagates in a rigid-walled and unflanged circular pipe with wavelength larger than radius, the acoustic motion is planar, much as in a bar. The incident sound waves are reflected at the end of pipe and some of them are transmitted. The reflection coefficients and radiation impedance of the pipes were calculated, and the results demonstrated that the high frequency sound is radiated through the tapered sound-pipes effectively. It behaves like frequency filters.

캠축의 구조 진동 응답 및 응력

최명진,Choi, Myung-Jin 한국음향학회 2013 韓國音響學會誌 Vol.32 No.3

캠축의 진동 응답을 구하기 위해 캠축을 불균형 다단계 로터 베어링계로 해석하였으며, 복잡한 형상과 하중조건을 고려하여 유한요소법을 사용하였다. 유한요소 방정식을 유도한 후에 Newmark 법을 사용하여 진동 응답을 구하였다. V-8 엔진 캠축의 회전 진동 응답을 구하여 측정치와 비교하였다. 캠축의 변동 응력을 구하고, 응력 집중 효과를 고려한 다음에 Goodmann 식에 근거하여 피로 해석을 수행하였다. 캠축의 회전 진동에서는 굽힘 효과가 지배적이며, 인접하는 베어링 간격에 가장 큰 영향을 받는다. 캠축에 가해지는 하중의 변화가 클 경우에는 하중의 변화에 상응하여 시간에 따라 변화하는 베어링 계수를 적용하여야 함을 알 수 있었다. To get vibration responses, a camshaft is modelled as an unbalanced multiple rotor bearing system. Because of complex geometry and complicated load conditions, the finite element method is used. After the finite element equation of the system is constructed, Newmark's method is used to get the vibration responses. Whirl vibration responses of a V-8 engine camshaft are estimated and compared with measured responses. After the fluctuating stresses are obtained, fatigue analysis is performed based upon the modified Goodman's equation. Stress concentration effects are considered. In the whirl vibration of camshafts, the bending effect is dominant, and the bending deformation is dependent upon the span length between the adjacent bearing journals. For high speeds, the fluctuations of excitation forces are large, and it is known that nonlinear time varying bearing coefficients should be used for analysis.

우리나라 의료분쟁의 실태

최명진,Choe, Myeong-Jin 대한병원협회 1988 대한병원협회지 Vol.17 No.12