• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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• pp.166-172
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• 1997

In order to find out relationship between hit probability and gun firing of a moving tank, a turret and flexible gun system model has been developed using the recursive flexible multibody dynamics. For a firing simulation model, nodal coordinates for a finite element model of a flexible gun have been employed to include traverse loads to the gun tube due to moving bullet and ballistic pressure. Modal coordinates are also used to represent the motion induced gun vibration before a firing occurs. An efficient switching technique from modal equations to nodal equations has been introduced for an entire gun firing simulation with rotating turret.

• Structural Engineering and Mechanics
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• 제73권3호
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• pp.339-351
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• 2020

Earthquakes are natural disasters that cause serious social disruptions and economic losses. In particular, they have a significant impact on critical lifeline infrastructure such as urban water transmission networks. Therefore, it is important to predict network performance and provide an alternative that minimizes the damage by considering the factors affecting lifeline structures. This paper proposes a probabilistic reliability approach for post-hazard flow analysis of a water transmission network according to earthquake magnitude, pipeline deterioration, and interdependency between pumping plants and 154 kV substations. The model is composed of the following three phases: (1) generation of input ground motion considering spatial correlation, (2) updating the revised nodal demands, and (3) calculation of available nodal demands. Accordingly, a computer code was developed to perform the hydraulic analysis and numerical modelling of water facilities. For numerical simulation, an actual water transmission network was considered and the epicenter was determined from historical earthquake data. To evaluate the network performance, flow-based performance indicators such as system serviceability, nodal serviceability, and mean normal status rate were introduced. The results from the proposed approach quantitatively show that the water network is significantly affected by not only the magnitude of the earthquake but the interdependency and pipeline deterioration.

• 대한기계학회논문집A
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• 제29권8호
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• pp.1123-1131
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• 2005

In this paper, a formulation for a spatial sliding joint, which a general multibody can move along a very flexible cable, is derived using absolute nodal coordinates and non-generalized coordinate. The large deformable motion of a spatial cable is presented using absolute nodal coordinate formulation, which is based on the finite element procedures and the general continuum mechanics theory to represent the elastic forces. And the non-generalized coordinate, which is neither related to the inertia forces nor external forces, is used to describe an arbitrary position along the centerline of a very flexible cable. In the constraint equation for the sliding joint, since three constraint equations are imposed and one non-generalized coordinate is introduced, one constraint equation is systematically eliminated. Therefore, there are two independent Lagrange multipliers in the final system equations of motion associated with the sliding joint. The development of this sliding joint is important to analyze many mechanical systems such as pulley systems and pantograph/catenary systems for high speed-trains.

• 한국해양학회지:바다
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• 제12권3호
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• pp.234-238
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• 2007

현재까지 우리나라에선 연구자마다 각기 다른 세 가지 조석지각 기준(관측지점 경도 기준 지각, 표준시 자오선 기준 지각, 그리니치 자오선 기준 지각)을 사용하여 오고 있다. 이처럼 통일되지 않는 조석지각 정보체계는 전체적인 우리나라 조석의 특성이나 변화를 이해하는데 장애가 되고 있다. 이 연구에서는 올바른 조석지각 기준의 상호전환과 관련하여, 세 가지 지각기준에 관하여 자세히 살펴보았다. 이에 앞서 조석 조화분해 과정에서 분조의 지각이 어떻게 계산되며, 조석예측프로그램에선 계산된 지각이 어떻게 사용되게 되는지 살펴보았다. 또한 이것을 바탕으로 과거 일부 연구에서 불명확하게 기술된 조석지각의 정의에 관하여 논의하였다.

• 한국정밀공학회지
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• 제22권1호
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• pp.152-159
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• 2005

The dynamic properties between catenary and pantograph of high-speed train are very important factors to affect the stable electric power supply. So as to design the reliable current collection system, a multibody simulation model is needed. In this paper, the dynamic analysis method for a pantograph-catenary cable system of high-speed train is presented. The very deformable motion of a catenary cable is demonstrated using nonlinear continuous beam theory, which is based on an absolute nodal coordinate formulation, and the pantograph is modeled as a rigid multibody. The proposed method might be very efficient, because this method can present the nonlinear properties of a flexible catenary cable and set a various boundary conditions.

• 터널과지하공간
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• 제11권1호
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• pp.36-41
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• 2001

우리가 에너지원으로 사용하고 있는 연료는 40년이면 바닥이 난다는 게 일반적으로 알려진 사실이며 우리나라는 주거용에너지가 전체에너지 수요의 30∼40%를 차지하고 있는 실정이므로 주거용 에너지 절약의 한 방법으로서 지하공간의 사용을 검토해 봄직도 하다. 지하공간의 열 해석에는 그리드로 된 교점회로망을 구성하여 해석을 하게되는 데, 지금 시중에 나와있는 해석용 프로그램은 비싸고 큰 용량을 필요로 함으로 현장에서의 사용이 쉽지는 않다. 이 연구에서는 이러한 점에 착안하여, 교점회로망을 구성하여서 중심교점에 영향을 미치는 인접교점들의 열저항요소를 계산하여 행렬에 대입함으로써, 지중온도를 구하는 방법을 연구하여 실험현장의 실측치와 비교한 결과, 만족할 만한 결과를 얻었다. 따라서 이 방법을 적용하면, PC 에서도 값싼 계산용 프로그램 (C++, 포트란, 베이직 등)을 사용하여 지중온도를 쉽게 해석할 수 있을 것으로 생각된다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제30권6호
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• pp.529-539
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• 2008

Background and Purpose : Oral squamous cell carcinoma (OSCC) is one of the most aggressive tumors of the head and neck area. OSCC is known to preferentially metastasize via lymphatic system, and resulting cervical lymph node metastasis is the most reliable of treatment failure. But the biological mechanism of the regional nodal metastasis is not clear. So, we determined metastasis-related factors in orthotopic nude mouse models of OSCC. Experimental Design : Two cell lines-KB and YD-10B cells, established from human oral mucosal squamous cell carcinoma, were xenografted into the tissue space of athymic murine mouth floor. The mice were followed for tumor development and growth, the murine tumors were examined histopathologically for local invasion or regional or distant metastasis. Finally, we performed immunohistochemical assays with antiepithelial growth factor (EGF), EGF receptor (EGFR), phosphorylated EGFR (pEGFR), and anti-vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR)-2, phosphorylated VEGFR-2/3 (pVEGFR-2/3) antibodies. We also determined the microvessel density. Results : Transplantation of human OSCC tumor cells into the mouth floor successfully resulted in the formation of orthotopic tumors. KB cell line showed significantly higher tumor proliferation and higher nodal metastatic potential than YD-10B cell line. Furthermore, immunohistochemical staining demonstrated higher expression of EGFR/pEGFR, VEGF, and pVEGFR-2/3 as well as higher microvessel density in KB murine tumors than in YD-10B murine tumors. Conclusion : An orthotopic model of OSCC in athymic mice was established which copies the cervical lymph nodal metastasis of human OSCC. Our mouth floor model should facillitate the understanding of the molecular pathogenesis of cervical nodal metastasis of OSCC.

• 대한조선학회논문집
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• 제47권1호
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• pp.47-57
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• 2010

This study analyzes the dynamic response of a floating crane with a cargo considering an elastic boom to evaluate(or for evaluation of) its flexibility effect on their dynamic response. Flexible multibody system dynamics is applied in order to establish a dynamic equation of motion of the multibody system, which consists of flexible and rigid bodies. In addition, a floating reference frame and nodal coordinates are used to model the boom as a flexible body. The study also simulates the coupled surge, pitch, and heave motions of the floating crane carrying the cargo with three degrees of freedom by numerically solving the equation. Finally, the simulation results of the elastic and rigid booms are comparatively analyzed and the effects of the flexible boom are discussed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.583-588
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• 2007

This paper investigates the vibration characteristics of a wire-bonding transducer horn for high speed welding devices. The sample wire-bonder uses the input frequency of 136 kHz. The ultrasonic excitation causes the various vibrations of transducer horn and capillary. The vibration modes and frequencies close to the exciting frequency are identified using ANSYS. The nodal lines and amplification ratio of the ultrasonic horn are also obtained in order to evaluate the bonding performance of the sample wire-bonder system. The FEM results and experimental results show that the sample wire-bonder system uses the bending mode of 136 kHz as principal motion for bonding. The major longitudinal mode exists at 119 kHz below the excitation frequency. It is recommeded that the sample system is to set the excitation frequency at 119 kHz to improve bonding performance.

• 한국소음진동공학회논문집
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• 제14권2호
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• pp.150-156
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• 2004

In this paper, the dynamic behavior of a very flexible cable due to moving multibody system along its length is presented. The very deformable motion of a cable is presented using absolute nodal coordinate formulation, which is based on the finite element procedures and the general continuum mechanics theory to represent the elastic forces. Formulation for the sliding joint between a very flexible beam and a rigid body is derived. In order to formulate the constraint equations of this joint, a non-generalized coordinate, which has no inertia or forces associated with this coordinate, is used. The modeling of this sliding joint is very important to many mechanical applications such as the ski lifts. cable cars, and pulley systems. A multibody system moves along an elastic cable using this sliding joint. A numerical example is shownusing the developed analysis program for flexible multibody systems that include a large deformable cable.