• 한국군사과학기술학회지
• /
• 제14권6호
• /
• pp.1026-1030
• /
• 2011

This paper presented here contains development of variable stability system(VSS) control laws for the KIFS (Korean In-Flight Simulator) aircraft to simulate the dynamics of F-16 aircraft. Development of VSS Control law for pitch rate, roll rate, yaw rate simulation for three specified flight conditions using Model Following Technique with rate feedback autopilot for stability provision. The direct lift force controller was also added to the developed VSS control law to simulate the pitch rate and normal g-load simultaneously. The simulation results show high accuracy of F-16 aircraft's pitch, roll, yaw rate and g-load simulation.

• 한국전문물리치료학회지
• /
• 제13권3호
• /
• pp.102-110
• /
• 2006

To improve trunk stability, various exercise protocols were introduced into the clinical field. Trunk and lumbar stability exercises on unstable surfaces are especially recommended to improve lumbar stability. The purpose of this study was to compare abdominal oblique muscle activity during leg raising in hook-lying position among 3 different type of surface conditions (on floor (F), vestibular board (VB), and foam roll (FR)). Sixteen able-bodied volunteers, who had no medical history of lower extremity or lumbar spine disease, were recruited for this study. Surface electromyography (EMG) activity was recorded from the internal and external oblique muscles of both sides. The normalized EMG activity was compared using a one-way repeated ANOVA. The results showed that the EMG activities of the internal oblique and external oblique of the lifted leg side during straight leg raising significantly increased under the FR condition when compared to the F condition. There was no significant difference of the EMG activity in abdominal oblique muscles between the VB and the FR conditions. The EMG activity of the internal oblique of supported leg side during the straight leg raising was significantly greater under the FR condition than the VB and F conditions (p<.05). The composition ratio of EMG activity of internal oblique muscles during straight leg raising was significantly increased under the FR condition. Therefore, straight leg raising exercise on foam roll in hook lying position could be beneficial to improve trunk and lumbar stability.

• 한국산학기술학회논문지
• /
• 제16권10호
• /
• pp.6977-6984
• /
• 2015

품질 향상을 위해 연속적인 소성 변형을 이용한 롤 포밍 공정에 피어싱, 벤딩, 트리밍 등 별도의 가공공정을 통합한 볼 슬라이드 레일의 멀티 롤 포밍 공정의 필요성이 대두되고 있다. 하지만 프레스기의 진동 및 소음은 이 공정에서 생산되는 슬라이드 레일의 품질 저하를 유발한다. 본 연구에서는 롤 포밍 유한요소 프로그램으로 최적 변형률을 고려하여 롤을 설계하였다. 그리고 멀티 공정의 정적 안정성을 예측하기 위해 구조해석 프로그램으로 프레스기에 대한 응력 및 변형량을 계산하였다. 또한 공진영역에서의 장치들의 운전을 회피하기 위해 Modal 해석을 통해 1, 2차 모드에서의 고유진동수를 계산하였다. 그 결과 공정의 동적 안정성 개선을 확인하기 위해 마이크로폰과 가속도계를 이용하여 기존 및 연구 공정들의 소음, 진동의 크기를 비교하였다. 그리고 기존 및 연구 공정으로 생산되어진 레일의 폭 치수와 표면거칠기를 측정하였다. 따라서 해석 및 실험적 연구를 통해 멀티 롤 포밍 공정이 안정하다는 것을 알 수 있었다.

• 수산해양기술연구
• /
• 제47권3호
• /
• pp.248-256
• /
• 2011

The inherent efficiency of a ship would be prior to any other quality factors in ship's safety, because lack of it may give rise to a serious sea casuality even if it were a light mistake in operation. And the representative casualty comes from a deficiency of stability and an operating error combined would be capsizing. The Korean offshore large purseiner looks to have a structural weak point with small range of stability in spite of her big initial metacentric height, and have various type of roll reduction devices in order to cover up the defect. The aim of this study is to grasp for the roll reduction characteristics of the purseiner with bilge keel only and a stern keel additionally attached. The results are summarized as follows; The rolling angle of the model ship was increased in accordance with increase of the wave period and height, especially at close to the natural wave period of her, and the trends were more distinguished in the situation of bilge keel only installation than in the stern keel additionally installed. And stern keel has not noticeable effect on the reduction of the roll in the light ship condition, but has a little effect in full load condition.

• 융합신호처리학회논문지
• /
• 제4권2호
• /
• pp.53-60
• /
• 2003

무게중심이 높은 차량은 코너링 시에 전복되는 위험을 방지하기 위해 서스펜션 롤 강성이 매우 커야 한다. 어떤 경우에는 효과적인 롤 강성이 주로 타이어 컴플라이언스에 의해 결정되는데, 그러한 경우에는 히브(heave) 진동의 감쇠를 위해 사용되는 쇽업쇼바는 롤 진동을 억제하는 데에는 별다른 효과가 없다. 따라서, 차량의 측면에 돌풍이 불거나 차량이 불규칙한 도로면을 통과하게 될 경우 차량이 좌우로 심하게 흔들리게 된다. 본 연구에서는 무게중심이 높은 차량의 안정성을 향상시키기 위해서 롤 모드 상에서 댐핑을 증가시킬 수 있는 제어기법이 제안되었다. 롤 운동의 댐핑을 제공하기 위해 요구되는 궤환신호로 앞 또는 뒤 또는 앞 뒤 바퀴의 조향각이 사용되었다. 그 이유는 그 신호들이 롤 운동과 매우 밀접하게 관련이 있기 때문이다. 제안된 제어기법은 중고속에서 매우 효과적이고 쇽업쇼바와는 달리 외적 입력에 대해 외란 모멘트를 생성하지 않고 롤 모드를 안정화시키는 것이 가능하다. 이론적으로 제시된 제어기법에 대한 타당성을 컴퓨터 시뮬레이션으로 확인하였다.

• 한국기계가공학회지
• /
• 제18권12호
• /
• pp.45-51
• /
• 2019

As the separator becomes thinner, the role of thermal stability becomes more important in ensuring the high capacity of medium- and large-sized lithium-ion secondary batteries. In this study, we researched coating technology to improve the separator's thermal stability. We minimized the coating time by optimizing the design of a vertical two-stage coater that was thin, uniform, and capable of coating on both sides at the same time with a maximum 2㎛ thickness coating layer of fluorinated polymer (PVdF-HFP) on the bare polyethylene (PE) separator, which increased the thermal stability. In addition, during the coating process, a dual-jacket-roll method of drying was developed that increased the drying effectiveness without thermal damage to the separator. We also investigated the thermal stability of the separator manufactured from a coating machine, and studied the battery-applied performance by making a lithium-ion pouch battery.

• Structural Engineering and Mechanics
• /
• 제68권5호
• /
• pp.633-638
• /
• 2018

One of the important problems in the vehicle design is vehicle handling and stability. Effective parameters which should be considered in the vehicle handling and stability are roll angle, camber angle and scrub radius. In this paper, a planar vehicle model is considered that two right and left suspensions are double wishbone suspension system. For a better analysis of the suspension geometry, a kinestatic model of vehicle is considered which instantaneous kinematic and statics relations are analyzed simultaneously. In this model, suspension geometry is considered completely. In order to optimum design of double wishbones suspension system, a multi-objective genetic algorithm is applied. Three important parameters of suspension including roll angle, camber angle and scrub radius are taken into account as objective functions. Coordinates of suspension hard points are design variables of optimization which optimum values of them, corresponding to each optimum point, are obtained in the optimization process. Pareto solutions for three objective functions are derived. There are important optimum points in these Pareto solutions which each point represents an optimum status in the model. In other words, corresponding to any optimal point, a specific geometric position is determined for the suspension hard points. Each of the obtained points in the Pareto optimization can be selected for a special design purpose by designer to create an optimum condition in the vehicle handling and stability.

• 소성∙가공
• /
• 제5권3호
• /
• pp.232-238
• /
• 1996

A dynamic mill set-up technique was developed to achieva a more precise roll gap set-up of the finishing mill stands for steel strip rolling. In the conventional mill set-up model the set-up values such as roll gap and roll speed are determined before the sheet bar reached the entry side of the finishing mill train and maintained constant until the strip top end passes through the last stand. In the way however a dynamic set-up logic that gives a way to adjust the roll gap value of the final mill stand for the strip ingoing from the ahead of the front stand was developed and attached to the existing set-up model. The roll gap modification is based on the analysis of the observation in the third stand of the finishing mill train. The dynamic set-up model was proved very effective for the more precise mill set-up and for operational stability in the hot strip finishing mill train.

• 한국생산제조학회지
• /
• 제18권3호
• /
• pp.328-335
• /
• 2009

In order to 1ransport the steel roll coil effectively and safely to the destination, the stability of the steel roll coil which induced the minimum movements during the 1ransportation was s1rongly required. The basic 1ransportation equipment for the steel roll coil such as the wedge is made of 100% imported wood known as the apitong. However, the material characteristic such as the rigidity has caused permanent damages to the steel roll coil and the damaged steel roll coils were not easily restorable. Thus it was unsuitable for other purposes. The introduction of new materials to manufacturing wedges which would have a good recovery performance and thus enable the wedge prevention or reduction to the steel roll coil or any other products during the 1ransportation is needed. Due to the fact that recovering damage of the coil is almost impossible, we have to find the new type of wedge that can substitute the apitong wedge. Therefore, we are going to develop a wedge that does not damage rolled steel coil and has better recovery and softness than existing apitong wedge.

• 항공우주시스템공학회지
• /
• 제10권3호
• /
• pp.39-43
• /
• 2016

In this paper, a wind-tunnel test is accomplished to investigate the roll characteristics of a variable-span wing flying inside a channel. The factors that affect the roll characteristics of the wing were identified by analyzing the measured data; accordingly, when the wing is flying without both the ground and sidewall effects, the asymmetric wing extension causes the roll moment. Both the ground and the sidewall can increase the roll moment, but when the wing is affected by both the ground and the sidewall, the roll moment does not increase as much as the case where the wing is only affected by the ground. Also, the aerodynamic characteristics of the flying wing inside a channel are the nonlinear function of the wing height and the gap between the wingtip and the sidewall, both of which should be considered in a study of the stability and the flight control of the wing-in-ground effect of the vehicle flying inside a channel.