• 산업기술연구
• /
• 제26권A호
• /
• pp.47-54
• /
• 2006

To improve passenger safety, seat belt systems with pre-tensioner that tightens seat belt webbing using explosive just before collision are widely used these days. Even though seatbelt must not unlatched without passengers' operation. explosive power of pre-tensioner can cause unlocking of a buckle. To prevent the unlocking, an anti-g mass that blocks displacement of the release button has been attached to the buckle. In this study, the dynamics and statics of locking mechanism associated with operation of anti-g buckle has been theoretically investigated, and important design variables that affect the operation of anti-g buckle have been identified. Through the total seat belt system's dynamic simulation using force and displacement inputs obtained from seat belt sled test, design of the proposed anti-g buckle has been validated.

• 동력기계공학회지
• /
• 제14권6호
• /
• pp.35-40
• /
• 2010

This article deals with the numerical analysis results of stiffness of diaphragm spring used in the clutch of a manual transmission. In order to investigate the relationship of the force and displacement in a diaphragm spring, we have established a numerical model of diaphragm spring using a well-known analytic model of Belleville spring and a cantilever beam model for the finger part of diaphragm spring. Using the stress and strain relations of Belleville spring and cantilever beam, we propose the analytic equation of motion of diaphragm spring for the use of a clutch automated actuator in an automated manual transmission. The proposed analytic model represents the typical dynamic characteristics of diaphragm spring along with the release bearing travel. And it is characterized in a closed-form equation, therefore it can be used for the further study of development of actuator and control law of clutch automating mechanism.

• Macromolecular Research
• /
• 제16권5호
• /
• pp.418-423
• /
• 2008

Poly[(R)-3-hydroxy butyrate] (PHB) and methoxy poly(ethylene glycol) (mPEG) were conjugated by the transesterification reaction with tin(II)-ethylhexanoate (Sn(Oct)-II) as a catalyst. Hydrophobic PHB and hydrophilic mPEG formed an amphiphilic block copolymer which was formed with the self-assembled polymeric micelle in aqueous solution. In this study, we tried to determine the optimum ratio of hydrophobic/hydrophilic segments for controlled drug delivery. The particle size and shape of the polymeric micelle were measured by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Their size were 61-102 nm with various block ratios. Griseofulvin was loaded in the polymeric micelle as a hydrophobic model drug. The loading efficiency and release profile were measured by high performance liquid chromatography (HPLC). The model drug in our system was constantly released for 48 h.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 추계학술대회 논문집
• /
• pp.1067-1071
• /
• 1997

A new type of gripper for micrometer-size objects is developed using piezoelectric multi-layer benders. It is composed of three chopsticks, two of which are designed to grip micro-objects. The third one is reserved for helping the two when objects are released from the chopsticks. It is well known that a micro object is much easier to grasp than to release it after holding it. The electrostatic force between the chopsticks and an object is believed to be the main cause of adhesion in a dry environment. The surface tension becomes very important when liquids are present or in a liquid. The third auxiliary chopsticks is introduced to solve there surface effects. All the three chopsticks are made of tungsten wires with sharpened ends by etching. When grasping microparts, the two chopsticks are utilized, and, when releasing them anywhere the parts are located, the third one reduces the electrostatic force between the objects and the chopstick may be to help the other two chopsticks to hold an objects in a desired orientation. We constructed the three chopstick gripoer for micro objects and test their function by holding and releasing an object of a diameter of 100 micrometers. We make use of open loop voltage control. The bender displacement resolution is sub-micrometer. The gripping forces, about tens of mN are obtained. The experiment shows that the third auxiliary chopstick functions effectively.

• Ocean Systems Engineering
• /
• 제14권2호
• /
• pp.157-169
• /
• 2024

The sudden release of water from a dam failure can trigger bores on a flat surface and exert substantial impact forces on structures. This flow poses a high-risk flood hazard to downstream urban areas, making it imperative to study its impact on structures and devise effective energy dissipators to mitigate its force. In this study, a combination of Genetic Algorithm optimization and numerical modeling is employed to identify the optimal energy dissipator. The analysis reveals that a round arc-shaped structure proves most effective, followed by a triangular shape. These shapes offer wide adaptability in terms of structure dimensions. Structures with higher elevation, especially those with round or triangular shapes, demonstrate superior energy dissipation capabilities. Conversely, square-shaped structures necessitate minimal height to minimize impact forces. The optimal width for dissipating energy is found to be 0.9 meters, allowing for effective wave run-up and propagation. Furthermore, the force exerted on structures increases with higher initial water levels, but diminishes with distance from the dam, highlighting the importance of placement in mitigating impact forces.

• 대한기계학회논문집A
• /
• 제40권11호
• /
• pp.963-970
• /
• 2016

본 연구는 가속페달에 반력을 생성하여 운전자의 경제운전을 유도하기 위한 에코페달의 설계와 성능 검증을 다룬다. 에코페달의 제어로직은 사전에 설정된 "허용가속도"를 바탕으로 현재 속도에서 허용되는 연료소비량을 정하고 이를 실제 연료소비량과 비교하여 에코페달의 작동을 결정하는 방식을 제안하였다. 폐달 반력은 운전자가 충분히 인지하되 불쾌감을 느끼지 않아야 하며, 차량의 정상 거동에 간섭이 없어야 한다. 스텝형과 램프형 반력 등과 같이 페달 답력이 급속하게 증가하는 형태의 반력은 반력 작동이 멈춘 직 후 운전자의 답력에 의한 급작스러운 가속 현상 때문에 적용이 어렵고, 이러한 문제가 없는 진동형 반력을 채택하였다. 진동형 반력의 주파수, 진폭, 작동시간은 운전자의 주관적 평가와 연비 향상 효과를 고려하여 결정하였다. 본 연구에서 제안된 에코페달을 차량에 장착하여 주행시험을 실시한 결과 고속도로와 시내주행에서 각각 13%와 15%의 연비향상 효과를 보여주었다.

• 약학회지
• /
• 제24권1호
• /
• pp.15-25
• /
• 1980

The investigation is concerned with the action of ginseng saponin on the contractile force in the rat heart and with the elucidation of the mechanism of the action. The effect of total ginseng saponin, ginsenoside Rb$_{1}$ of protopanaxadiol derivatives and ginsenoside Re of protopanaxatriol derivatives on the contractile force in isolated spontaneously beating normal rat heart was investigated. Total ginseng saponin was obtained from white ginseng by the method of Shibata and Namba. Ginsenoside Rb$_{1}$ and ginsenoside Re were isolated by the method of and Han, respectively. Total ginseng saponin exhibited a slight increase of the contractile force. Ginsenoside Rb$_{1}$ increased markedly the contractile force and dose dependent increase in contractile force was observed. However, ginsenoside Re did not increase the contractile force, but it prevented spontaneous decrease of the contractility of the heart. The mixture of the same dose of ginsenoside Rb$_{1}$ and Re showed a slight increase in the contractile force and its effect was similar to that obtained by total ginseng saponin. Pretreatment with propranolol abolished the positive inotropic effect of ginsenoside Rb$_{1}$ and the positive inotropic effect of ginsenoside Rb$_{1}$ was not observed in a reserpinized rat heart. Pretreatment with ginsenoside Re decreased or abolished the positive inotropic effect of epinephrine. Activities of Na+, K+ -ATPase were inhibited by ginsenoside Rb$_{1}$, total ginseng saponin and ginsenoside Re and these inhibitory effects were dose dependent. The results suggest that catecholamine release or inhibition of Na+, K+ -ATPase activities may be involved in the positive inotropic effect of gindenoside Rb$_{1}$. Ginsenoside Re counteracted the positive inotropic effect of ginsenoside Rb$_{1}$.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.246-250
• /
• 2003

In this study, two new types of micro-grippers in which micro-fingers are actuated by piezoelectric multi-layer benders and stacks are introduced for the manipulation of micrometer-sized objects. First, we constructed a 3-chopstick-mechanism tungsten gripper, which is composed of three chopsticks: two are designed to grip micro-objects, and tile third is used to help grasp and release the objects through overcoming especially electrostatic force among some surface effects including electrostatic, van der Waals forces and surface tension. Second, a 2-chopstick-mechanism silicon micro-gripper that uses an integrated force sensor to control the gripping force was developed. The micro-gripper is composed of a piezoelectric multilayer bender for actuating the gripper fingers, silicon fingertips fabricated by use of silicon-based micromachining, and supplementary supports. The micro-gripper is referred to as a hybrid-type micro-gripper because it is composed of two main components; micro-fingertips fabricated using micromachining technology to integrate a very sensitive force sensor for measuring the gripping force, and piezoelectric gripper finger actuators that are capable of large gripping forces and moving strokes. The gripping force signal was found to have a sensitivity of 667 N/V. To the design of each of components of both of the grippers. a systematic design approach was applied, which made it possible to establish the functional requirements and design parameters of the micro-grippers. The micro-grippers were installed on a manual manipulator to assess its performance in tasks such as moving micro-objects from one position to a desired position. The experiment showed that the micro-grippers function effectively.

• 한국의상디자인학회지
• /
• 제23권1호
• /
• pp.37-45
• /
• 2021

This study observed the release of microplastics according to washing weights and filtering conditions, measured microplastic generation rates, fiber lengths, and fiber diameters. This study attempted to present data for the development of filters that decrease microplastic generation. For test samples, polyester piled knit fabric (cut-pile) was selected, which currently has the highest amount of consumption in the clothing industry, but can easily cause marine pollution because of its low biodegradability. For test equipment, a drum washer was used and microplastics were collected using two filter pore sizes, 5 ㎛ and 20-25 ㎛. Microplastic fibers weights and lengths were measured. The results of the experiment showed the following: 1) The release of microplastics differed according to the fabric weights and washing process; 2) washing fabric weights showed a differences in the collection amount according to the filter pore size (5 ㎛, 20-25 ㎛); 3) observations of differences in the lengths of the microplastics that occur during the washing process by filter pore size were made. Fibers with shorter lengths appeared with filter pore sizes of 5㎛ in comparison to filter pore sizes of 20-25㎛. The results from this study on microplastic generation by fabric during washing, demonstrated the following conclusions that can be used to reduce the release of microplastics. First, the release of microplastics according to fabric weights and washing courses are affected by physical force. Therefore, it is necessary to reduce the amount of physical force due to water flow, increase the fabric weight, or wash the material in low temperatures. Second, in the manufacturing of washing machines, microplastic filtration can be promoted or legislatation supporting microplastic filtration can be introduced.

• 폴리머
• /
• 제29권4호
• /
• pp.369-374
• /
• 2005

본 실험에서는 레몬 오일을 함유한 알긴산 칼슘 마이크로캡슐을 에멀션-내부 젤화법으로 제조하였으며, 방출실험을 통하여 아로마테라피의 가능성에 대해 살펴보았다. 적외선분광분석(FT-IR)과 시차주사열량계(DSC)를 통해 레몬 오일의 봉입 여부를 확인하였고, 제조된 마이크로캡슐의 직경 및 형태를 주사전자현미경(SEM)으로 관찰하였다. 제조된 마이크로캡슐은 평균 $4\~7$um직경 및 $50\~85\%$의 캡슐화를 보였으며, $37^{circ}C$에서 적외선 수분계(IMDB)를 통한 방출실험 결과. 알긴산 및 $CaCl_2$의 농도가 증가할수록 가교밀도가 증가하므로 레몬 오일의 방출률이 감소함을 관찰할 수 있었다. 또한, 물리적 압력을 통한 방출실험을 실시함으로써, 캡슐벽의 붕괴와 방출속도가 외부적인 요인에 의해 방출속도를 제어할 수 있음을 확인하였다.