• 대한기계학회논문집A
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• 제33권3호
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• pp.210-217
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• 2009

This paper presents the analytical prediction of stability lobes in milling. The stability lobes are obtained by measuring the frequency response function (FRF) of a machining center at the cutting point of the end mill cutter, identifying cutting constants, and approximating cutting force coefficients. The stability lobes are experimentally verified through cutting tests.

• 대한조선학회지
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• 제15권1호
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• pp.7-9
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• 1978

In this calculation of statical stability of a ship, mechanical integrator was used most popularly and the direct calculation method such as a Barn's wedge method was also adopted in some cases. Both of the above method was developed for manual calculation which include mechanical integration or drafting procedure on body plan. Therefore, the computerization of stability calculation by the above method is very difficult. In this paper a simplified method for stability calculation is suggested, with based on hydrostatic data and immerged wedged characteristics.

• 대한물리의학회지
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• 제10권2호
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• pp.35-45
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• 2015

PURPOSE: The aim of this study is to investigate how upper thoracic manipulation and cervical stability training affects cervical range of motion and neck disability index of patients with chronic mechanical neck pain. METHODS: 30 patients with chronic mechanical neck pain, and randomly divided into the upper thoracic manipulation and the cervical stability training group. Upper thoracic manipulation group was conducted to the upper thoracic manipulation, and cervical stability training was conducted to the cervical stability training. Intervention period was 6 weeks, and 3 sessions, each of which was run for 5~10 minutes. The subjects were measured neck range of motion before and after intervention by electro-goniometer. Neck disability index was used to measure neck disability index Korean version. RESULTS: Comparison within groups, there were significant difference in neck range of motion before and after intervention, and Neck disability index significantly reduced in the cervical stability training group. The comparison between groups, there were no significant difference in neck range of motion and neck disability index. CONCLUSION: Upper thoracic manipulation and cervical stability training to the patients with chronic neck pain was helpful to improve neck range of motion and cervical stability training was helpful to improve neck disability index.

• 한국지반공학회논문집
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• 제32권1호
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• pp.19-33
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• 2016

강우의 침투가 사면안정에 미치는 영향을 평가하기 위해 강우의 침투해석을 수행하고 그 결과를 한계평형해석에 적용하는 안정해석 절차가 널리 사용되고 있으나 지반은 흙 입자, 물과 공기로 이루어진 3상의 물질이므로 사면을 통한 강우의 침투를 엄밀하게 해석하기 위해서는 물, 공기의 흐름과 흙의 응력-변형거동이 완전 연관된(fully coupled) 식을 고려해야 한다. 본 연구에서는 공기와 물의 흐름이 사면의 역학적 안정에 미치는 영향을 연구하기 위하여 우리나라에 널리 분포하는 풍화잔류토 사면에 대하여 3상이 연동된 흐름해석을 수행하였다. 강우침투가 사면안정에 미치는 영향을 평가하기 위하여 강도감소법에 의한 사면 안정해석을 수행하였다. 해석결과에 의하면 침투하는 강우가 공기를 밀어내 공기의 흐름이 발생하고 공기압이 증가하였다. 이러한 간극에서의 물과 공기의 상호작용은 사면의 응력-변형거동에 영향을 미쳐 공기의 흐름을 고려하지 않은 흙 입자-물의 연관해석의 결과와는 다른 사면안정 거동을 보였다.

• 대한기계학회논문집A
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• 제36권11호
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• pp.1319-1326
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• 2012

본 논문은 구동력이 자전거의 self-stability 에 미치는 영향을 해석한다. 운전자의 제어를 고려하지 않는 자전거의 self-stability 는 자전거의 선형 모델로부터 고유치를 구하여 해석 할 수 있다. 전륜과 후륜에 작용하는 자전거 구동력을 고려한 선형모델을 개발하고 이로부터 구동력이 안정성에 미치는 영향을 규명하였다. 선형모델의 결과가 다물체 동역학 모델의 시뮬레이션을 통한 비선형 자전거 모델에서도 같은 결과를 보임을 확인하였다.

• International Journal of Aeronautical and Space Sciences
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• 제12권1호
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• pp.78-83
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• 2011

Traditional autopilot design requires an accurate aerodynamic model and relies on a gain schedule to account for system nonlinearities. This paper presents the control architecture applied to a dynamic model inversion at a single flight condition with an on-line neural network (NN) in order to regulate errors caused by approximate inversion. This eliminates the need for an extensive design process and accurate aerodynamic data. The simulation results using a developed full nonlinear 6 degree of freedom model are presented. This paper also presents the stability evaluation for control systems to which NNs were applied. Although feedback can accommodate uncertainty to meet system performance specifications, uncertainty can also affect the stability of the control system. The importance of robustness has long been recognized and stability margins were developed to quantify it. However, the traditional stability margin techniques based on linear control theory can not be applied to control systems upon which a representative non-linear control method, such as NNs, has been applied. This paper presents an alternative stability margin technique for NNs applied to control systems based on the system responses to an inserted gain multiplier or time delay element.

• Archives of Metallurgy and Materials
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• 제65권3호
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• pp.1001-1004
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• 2020

We investigated the austenite stability and mechanical properties in FeMnNiC alloy fabricated by spark plasma sintering. The addition of Mn, Ni, and C, which are known austenite stabilizing elements, increases its stability to a stable phase existing above 910℃ in pure iron; as a result, austenitic microstructure can be observed at room temperature, depending on the amounts of Mn, Ni, and C added. Depending on austenite stability and the volume fraction of austenite at a given temperature, strain-induced martensite transformation during plastic deformation may occur. Both stability and the volume fraction of austenite can be controlled by several factors, including chemical composition, grain size, dislocation density, and so on. The present study investigated the effect of carbon addition on austenite stability in FeMnNi alloys containing different Mn and Ni contents. Microstructural features and mechanical properties were analyzed with regard to austenite stability.

• Smart Structures and Systems
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• 제25권4호
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• pp.471-486
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• 2020

Stability analysis of three-layered piezoelectric doubly curved nano shell with accounting size dependency is performed in this paper based on first order shear deformation theory and curvilinear coordinate system relations. The elastic core is integrated with sensor and actuator layers subjected to applied electric potentials. The principle of virtual work is employed for derivation of governing equations of stability. The critical electrical and mechanical buckling loads are evaluated in terms of important parameters of the problem such as size-dependent parameter, two principle angle of doubly curved shell and two parameters of Pasternak's foundation. One can conclude that mechanical buckling loads are decreased with increase of nonlocal parameter while the electrical buckling loads are increased.

• 한국전기전자재료학회논문지
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• 제35권1호
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• pp.50-57
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• 2022

Reliability of CMOS has been severed under aggressive device scaling. Conventional technologies such as lightly doped drain (LDD) and forming gas annealing (FGA) have been applied for better device reliability, but further advances are modest. Alternatively, electro-thermal annealing (ETA) which utilizes Joule heat produced by electrodes in a MOSFET, has been newly introduced for gate dielectric curing. However, concerns about mechanical stability during the electro-thermal annealing, have not been discussed, yet. In this context, this paper demonstrates the mechanical stability of nanosheet FET during the electro-thermal annealing. The effect of mechanical stresses during the electro-thermal annealing was investigated with respect to device design parameters.

• 정보저장시스템학회논문집
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• 제11권2호
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• pp.31-35
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• 2015

The Blu-ray Disc Recordable-Triple Layer (BD-R TL) media is considered as one of strong candidates for archival application among optical media formats, due to its large capacity. However, the long-term stability and degradation aspect have not been fully understood yet for BD-R TL media. Thus, the BD-R TL media were recorded at full tracks and analyzed by the random-symbol error rate (R-SER) measurement at different recording layers and recording positions after the accelerated aging test to understand its long-term stability. Finally, the general degradation aspect of BD-R TL media was discussed to improve the long-term stability.