Roll-on and roll-off (Ro-Ro) ship is the most economical transporting method for large freights such as train, helicopter, and aircraft body. To ship a large freight to a designated location on deck of Ro-Ro ship, tractor is used to pull a trailer with a connecting link of goose neck shape, on which the freight is secured. When the freight is long enough, the trajectory of trailer is not same as that of trailer and is a three dimensional path, which can cause any collision with ramp, gate, and obstacles in the deck. This research proposes a method of calculating possible trajectories to drive a tractor, along which does not cause any collision. Assuming reasonably low speed of a tractor, the proposed method generates possible tractor paths based on Bezier curve to calculate the trailer path considering tilt of tractor and trailer when they go up the inclined ramp. Finally, it calculates the best three paths without any collision in order of priority with minimum shipping time. The proposed method can be useful for the transport company to determine the shipping possibility as well as to generate driving order for a tractor driver.

Most car body parts are manufactured using thin plates to reduce their weight, and completed assemblies typically have numerous spaces. Because cars are not designed to be completely watertight, rain or wash water may leak into the interior spaces of the assembly through gaps or inlets. When water enters a space and is not drained sufficiently, it can fill the space and overflow into unexpected channels, causing severe problems such as part corrosion and electric shock. In our research, based on a decomposition model representation, we have developed a program to graphically simulate all possible flows within the interior spaces between car parts. Our program can simulate the locations of outlets and overflow channels into unexpected regions, and thus help designers verify the effectiveness of their designs before manufacturing, which can therefore reduce the development time and costs. In particular, since the program can simulate overflow when a car in both horizontal and inclined positions, it can prevent possible design errors by engineers who are accustomed to designing cars only in a horizontal orientation. Our developed method can also be applied to aircraft and ship designs.

Obtaining reliable winding paths for non-axisymmetric shapes with current filament winding technologies is still a challenge. In this study, an algorithm was developed for generating geodesic and non-geodesic paths that are slippage- and bridging-free and can be applied to axisymmetric as well as non-axisymmetric mandrel models represented by triangular meshes. By performing a stability analysis on the winding path on a curved surface, the non-slipping and non-bridging conditions on a triangular mesh are deduced. Then, according to the inverse process of stability analysis, the next path point that satisfies the stability conditions is determined. In this method, the surface normal vector is calculated by a geodesic rather than via the weighted average method. Consequently, a stroke of the winding path is constructed by adding the next path point recursively. In addition, strategies for generating stable paths on a mandrel surface that includes concave regions are presented to avoid bridging.

Filament winding is a process in which glass or carbon fibers are wound around a mandrel to form fiber-reinforced structures of a desired shape. The strength of the fiber-reinforced part is maximized when the fiber direction coincides with the direction of the major principal stress of the part. Previous studies addressed methods to calculate the winding paths of maximum strength by adjusting the mandrel shapes. However, these methods are not appropriate for predetermined shapes that are fixed to satisfy certain special requirements. This study proposes a method to generate filament-winding paths using the principal stress fields of the part to be manufactured. In this method, variable winding directions as close as possible to the major principal stress directions of the product are calculated to generate filament-winding paths that can support the maximum load without slippage. The proposed method had the advantage of not being limited by the complexity of axisymmetric mandrel shape.

The filament winding method is widely used to manufacture lightweight, strong, composite products. To reduce winding time, the method of winding by filament band, which consists of several roving tows, is used. A computer numerical control winding machine is used with input path commands for precise winding operation. Before filament winding, users should verify by simulation that the input path is appropriate for the winding without any erroneous operation. Furthermore, prior to starting the winding operation, the usage length of each tow must to be checked because the manufacturing process stops unexpectedly if the tow on the creel runs out. In this work, we used the geodesic equation to generate a filament band surface and calculate the usage length of each tow. We also proposed a graphic display method to make the visual effect in accord with the real winding process. To verify the presented algorithm, a program for three-dimensional real-time graphic visualization of filament band winding process was developed.

A door checker holds a car door at several opening angles and limits the maximum door opening, so that the door does not bump against to passengers. Recently, the performance of door checker becomes more important as the feeling of door opening and closing effects on the quality of a car. However, some of door checkers make squealing noise when they are used for ages, which causes consumer's complaints as well as decreasing commercial value of the product. In this study, after various experiments for the noise, we concluded that the major reasons of the noise are acceleration of wearing and loss of lubricant due to impurities in working parts. Therefore, we developed a new mechanism of door checker which can resolve the major reasons of the noise. The developed mechanism is effective to prevent inflow of impurities and loss of lubricant by locating working parts in the case. We also proved that the developed mechanism does not make any noise after the test of 50,000 times of operations.

We generate geodesic or nongeodesic trajectories for filament winding based on the StereoLithography model. The discrete trajectory is traced out by constantly appending a new propagation point determined from the two most recent points of the path. According to differential geometry and discrete geometry theory, nonslippage and nonbridging conditions are added to constrain the propagation point to obtain a stable winding trajectory. This method can be applied to any convex surface, either axisymmetric or nonaxisymmetric shapes. An application for pressure vessels is implemented to validate the feasibility.

대부분의 오븐 렌지는 위에서 아래로 여는 도어로 되어 있다. 오븐 렌지와 같이 열고 닫는 가전제품의 경우 도어의 감성이 제품 전체의 품질에 영향을 준다. 도어의 감성 품질을 평가하는 항목은 문을 열 때의 개방력, 문을 닫을 때의 폐쇄력, 문을 완전 개방하였을 때 발생하는 튕김 현상이 있다. 개방력과 폐쇄력이 크면 소비자의 불만 요소가 될 수 있고, 튕김 현상이 크면 소비자가 도어를 열었을 때 도어는 물론 몸체에도 충격이 가해져서 파손의 우려가 있다. 감성 품질을 향상시키기 위해서는 개방력, 폐쇄력, 튕김 현상을 최소화하여야 한다. 본 연구에서는 개방력, 폐쇄력, 튕김 현상을 최소화하기 위해 비선형 캠과 스프링을 이용하여 기존의 이중 압축 스프링과 캠 구조를 개선한 메커니즘을 제안하였다. 또한, 제안된 메커니즘을 위해 비선형 캠을 설계 및 제작한 후 실제 오븐 렌지에 적용하여 기존보다 감성 품질이 우수함을 확인하였다. Most of oven range doors are opened from top to down. Feeling of door in case of home appliances including oven ranges affects the quality of product. The major factors to evaluate the feeling quality are opening force, closing force, and bouncing effect happened when the door is opened completely. If opening and closing forces become large, consumers may have complaints. If the bouncing effect becomes large, the impact can cause the body as well as the door to damage. Opening and closing forces, and bouncing effect must be minimized to improve the feeling quality. In this study, the mechanism which improves the existed dual compressive spring and cam structure is suggested by using nonlinear cam and spring. After the nonlinear cam is designed and manufactured for the suggested mechanism, this cam is confirmed to become more superior than the existed one by applying it to the practical oven range.

A four-link mechanism consisting of torsion bars is used for opening the trunk lid in most midsize sedans. When the weight of the lid is in equilibrium with the spring force exerted by torsion bars, the lid stops opening at a pop-up height. However, the actual pop-up height has large deviations from the specified height even with the same parts in the same car model, which leads to quality issues. Automotive manufacturers have experienced this deviation problem despite much effort to resolve it. In this research, we developed a multi-body dynamics model for the analysis of pop-up deviation of a trunk lid with torsion bars, which can simulate the actual pop-up motion of the trunk lid by considering kinematic constraints of the motion and friction forces in joints. We could also determine the most important factor that governs the pop-up height by sensitivity analysis of all parts. The developed system can be used for the analysis of other trunk lid systems to control the tolerance of parts.

The filament winding method is widely used to manufacture products of fiber reinforced plastics (FRP), such as high pressure vessels, launch tubes and pipes. For reducing winding time, the method of winding by filament band which consists of several filament fibers is used. NC winding machine is used for precise winding and NC path is needed. Before filament winding, users should verify that winding path which presented by a line is appropriate by filament winding simulation. Also, the used length of each filament is different. So, if the peak filament exhausted, it causes to stop manufacturing. In this research, we developed software which visualizes 3D graphic of filament band winding path and simulates winding process on real time. And we proposed algorithm about calculation of each filament usage. We use geodesic equation for generating filament band surface and calculating the usage length of each filament.

Automobiles, aircraft, and ships require tremendously many parts to be assembled. For developing such large assemblies, most companies accelerate the design process by having many design engineers in different functional or sectional design groups working concurrently. However, interferences and gaps can be found when the parts and sub-assemblies of different design groups are to be assembled. These error cause design changes and additional repair processes, resulting in an unexpected increase in costs and time delays. While the interference problem has been resolved by digital mockup and concurrent engineering methodology, many cases of the gap problem in the automotive industry have been covered by temporary treatments when the gaps are small enough to be filled with sealants. This kind of fast fix can cause leakage into the engine chamber and passenger cabin when the gap size is too big for filling or when the sealant gets old, which can turn fatal. With this research, we have developed a program to automatically find gaps between the parts of an assembly so that design engineers can correct their designs before the manufacturing stage begins. By using the method of decomposition model representation, the program can visualize gaps between complex car body parts as well as estimate their volumetric information. It can also automatically define the boundary between a gap and the exterior space. Although we have reviewed the benefits of the program by applying it to car development, it can also be applied to aircraft and ship designs comprising several parts. (C) 2014 Elsevier Ltd. All rights reserved.

Filament winding simulation, an essential part of a CAD/CAM integrated system, helps the user to gain an intuitive understanding of the process of filament winding, the winding pattern, and laminate structure, and so find and solve potential problems before actual production. This speeds up the R&D cycle and reduces costs. To reduce costs, instead of winding several individually tensioned rovings, a band is usually wound. Thus, we present a band winding visualization system. The simulation system includes filament-path generation and graphic display of the band. In generating band paths, each filament path that constitutes a band path is produced from an initial fiber path based on geodesic equations. To imitate the band winding process more realistically, model display methods are used to deal with the graphic relationships among the different models, including the band model, mandrel model, and winding machine model. The simulation system can visualize the band laying process with the corresponding winder movement, and runs stably and reliably.

본 웹사이트에 게시된 이메일 주소가 전자우편 수집 프로그램이나 그 밖의 기술적 장치를 이용하여 무단으로 수집되는 것을 거부하며, 이를 위반시 정보통신망법에 의해 형사 처벌됨을 유념하시기 바랍니다.

We present a postprocessing algorithm for 5-axis machines, which can be applied to types with two rotary axes (2R-3L) and three rotary axes (3R-2L). Five-axis machining requires a postprocessor for converting cutter-location (CL) data to numerical-control (NC) data. The existing methods for postprocessing use inverse kinematics equations from the forward kinematics. However, for 5-axis machines with three rotary axes, the inverse kinematics equations cannot be induced directly, because the forward kinematics equations are coupled. To derive the joint values from the forward kinematics equations, previous algorithms use iterative numerical methods for the postprocessing; this requires a search algorithm with much computation time and may fail to obtain a solution. Our algorithm has three advantages: first, the forward kinematics equations are not required; second, the method is reliable and eliminates the need for numerical methods for the inverse kinematics, which results in exact solutions; and finally, the proposed algorithm is generic for 5-axis machines, which can also be applied to 2R-3L 5-axis machines.

최근 보편화되고 있는 대형 냉장고는 냉동실과 냉장실이 나란히 있는 양문형이다. 그런데 양문형 냉장고에 대한 고객들의 가장 큰 불만 중의 하나는 양쪽 도어를 닫았을 때 높이 차가 발생하는 문제이며, 이를 도어의 단차라고 한다. 단차 문제의 가장 큰 원인은 냉장고가 설치되는 바닥이 평편하지 못하거나 사용 기간이 경과함에 따라 냉장고 캐비닛이 변형되기 때문이다. 이러한 단차를 확인하였을 때 지금까지는 고객이나 A/S 직원이 렌치 등을 사용하여 냉장고 하부의 지지나사를 조절하여 냉장고의 수평을 맞춘다. 그러나 이러한 작업은 대형 냉장고의 경우 상대적으로 힘이 약한 주부나 노인이 조작하기에는 어려운 작업일 뿐만 아니라 이러한 방식을 고객에게 요구하는 것 자체가 고객의 불만족을 야기할 수 있다. 본 연구는 이러한 문제를 해결하기 위해 도어의 단차를 자동으로 감지하여 양쪽 도어를 같은 높이로 자동으로 조절해주는 새로운 메커니즘을 제안하였다. 제안된 메커니즘은 공구를 사용하여 힘들고 번거롭게 단차를 조절할 필요 없이 냉장고의 도어를 열고 닫는 동작만으로 자동으로 단 맞춤이 가능하게 한다. Recently the increasingly common large refrigerator is the side by side(SBS) refrigerator whose freezing chamber and refrigerating chamber are set side by side. But one of the biggest dissatisfaction of customers about SBS refrigerator is that the two doors don't meet the same height when they are closed. It is called door height difference(DHD). The main cause of DHD is the unevenness of floor on which a refrigerator is placed or the cabinet deformation caused by long time use. When the DHD is confirmed, the customer or maintenance personnel use wrench to adjust the support screw to make the refrigerator to reach the horizontal position. But for big refrigerator, it is not only difficult for women and old people who don't have enough force to adjust it, but also inappropriate to require customers to do this job. In order to resolve this problem, this research proposes a new mechanism which can detect the DHD and adjust two doors to the same height automatically. The adjustment would be completed during opening and closing the doors, avoid needing hard operation with wrench by hand.

The French doors have the advantage that they can use inner space more efficiently due to without of partition between two rooms. However, when they are used for refrigerators, the door gaskets for sealing may cause interference of themselves during opening and closing, which causes fatal effect on sealing by worn out of the gaskets as well as increases door opening force. This research proposes a new mechanism for the French doors using the parallelogram motion of 4-bar linkage mechanism, which does not make any interference between gaskets. We manufactured the French doors of proposed mechanism to verify that they do not cause any interference during opening and closing, as well as opening force is decreased. The use of our developed mechanism is not limited to refrigerators, but can be extended to other industrial products with the French doors.

This paper presents algorithms for computing offsets of freeform curves. The approach first divides the original curve into several segments at the inflexion points. Based on the obtained new control polygon and its offsets, quadratic trigonometric splines are constructed to approximate the offset curves. Finally, the shape parameter value of trigonometric spline is determined to satisfy the required tolerance. The degree of the output curve is two, independent of the original degree. This method is able to generate completely overestimating offset curves, which can be uesd in NC machining for preventing over-cut. Furthermore, it can generate offset curves with the lowest number of control points compared with other works.