• Wind and Structures
• /
• 제7권6호
• /
• pp.359-372
• /
• 2004

Wind tunnel model studies were carried out to determine the wind load distribution on tributary areas near the gable-end of large, low-rise buildings with high pitch planar and curved roof shapes. Background pressure fluctuations on each tributary area are described by a series of uncorrelated modes given by the eigenvectors of the force covariance matrix. Analysis of eigenvalues shows that the dominant first mode contributes around 40% to the fluctuating pressures, and the eigenvector mode-shape generally follows the mean pressure distribution. The first mode contributes significantly to the fluctuating load effect, when its influence line is similar to the mode-shape. For such cases, the effective static pressure distribution closely follows the mean pressure distribution on the tributary area, and the quasi-static method would provide a good estimate of peak load effects.

• 대한조선학회논문집
• /
• 제39권2호
• /
• pp.28-33
• /
• 2002

조선소에서 사용되는 선각 외판 부재는 선박 한 척을 건조하는데 사용되는 부재의 수가 매우 많고, 각 가공 외판 부재는 상대적으로 크기가 크고 각각 상이한 부재 형상을 가지고 있다는 특징이 있다. 또한 이 중에서, 선체의 외판 곡 부재를 가공할 때는 각 부재의 초기 형상과 가공 목적형상에 대한 정보를 가지고 냉간, 열간 가공을 통하여 설계된 형상으로 가공을 수행하여야 한다. 이때, 최초 가공 시 및 추가 가공 중에 부재의 형상을 확인하여 주어진 정도에 부합할 때까지 가공을 수행 하여야 하며, 이와 같은 특징 때문에 선체 외판 부재의 가공 시에는 수시로 가공중인 부재의 형상 및 가공정도를 확인하여야 하는 과정, 즉 시간을 최소화하면서 효율적으로 가공형상을 확인하는 대형곡면 계측 기술과, 곡면 비교 기술이 필요하게 된다. 본 논문에서는, 이러한 가공환경 하에서 적용 가능성이 있는 효율적인 계측, 비교를 위한 S/W, H/W 통합 시스템 구축을 수행하였다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2009년도 추계학술대회 논문집
• /
• pp.289-292
• /
• 2009

The line array roll set process, as one of many kinds of incremental forming processes, is a continuous process in which a flat metal plate is formed into a singly or doubly curved plate through successive passes of forming rolls. It was found that the curvature level of the formed plates in the previous study was well over the curvature required in shipyards. This fact shows that the LARS method has considerable potential for shipbuilding applications. In a shipbuilding yard, hull forming is an important fabrication process in which flat plates are deformed into singly or doubly curved plates. The major purpose of the present study is to estimate experimentally the general applicability of the line array roll set process for the manufacture of ship hull plates. In this study, the target shapes are selected through investigation of the shape classification of ship hull plates that comprise a certain vessel. Forming processes for twisted shapes are analyzed with the finite element method (FEM). Finally, the results of experimental work for two types of target shapes are presented.

• 오토저널
• /
• 제7권3호
• /
• pp.42-55
• /
• 1985

The study is concerned with the investigation of curved line folding of developable surface from flat sheets of metal. General geometric relations among folding line, folded surface, folded angle are derived. From the derived geometric relations, the required plastic work and punch force are derived for the first approximation. Five methods of forming are suggested and the experiment is carried out using two chosen methods for the prismatic developable surfaces of which cross-sections have 103.deg.arc, 180.deg.arc, sinusoidal shape. In the die design for the tolding of prismatic developable surfaces, a stack of sheets were used to form shapes of the dies by which acceptable folded surfaces were obtained. The computed plastic work and punch force turned out to be in reasonable agreement with the experimental result.

• 한국의류학회지
• /
• 제39권6호
• /
• pp.826-837
• /
• 2015

This study analyzes the shapes of the adjustment of a Napoleon Collar which combines a stand collar with an upper collar. It established experimental conditions for fixing the conditions of Napoleon Collar components (lapel width, stand collar size and upper collar size) as well as varied the shape of the neckline, the length of the curve of a stand collar and the size of the drawing space at the center back. It produced 22 test clothes of muslin, which were dressed on dress form No. 8. The results indicate that: 1. Neckline shape determines the amount of stand and fall. Less curved neckline stands higher against the neck and a more curved neckline is laid lower onto the body. 2. A shorter curve length of a stand collar allows a longer roll line to fall farther away from the neck with more space between the neck and collar. However, the longer the depth of curve of a stand collar creates a shorter roll line that stands high against neck and closer to neck without any space between the neck and collar with a collar line matching the neck of the dress form. 3. The smaller the drawing space at the center back creates a shorter the style line of the upper collar. However, a narrower back width of the collar creates a bigger drawing space at the center back with a longer the style line and a more naturally placed back width of the collar. 4. A Napoleon Collar creates a longer depth of curve for a stand collar and a smaller drawing space at the center back that is tightly and stably stuck to the neck.

• Fisheries and Aquatic Sciences
• /
• 제3권2호
• /
• pp.156-162
• /
• 2000

Model experiments for a purse seine were carried out in order to measure the geometry of net shape and to estimate an enclosed volume by using 1177 scale model purse seine of 12.62m float line from an offshore mackerel purse seine. A model purse seine was set from a net box of shooting equipments and then pursing and hauling net by hauling equipment. The 3- D geometry shape of the purse seine net during hauling operation was measured by video image processing and tension of purse line by load cell. The 3-D geometry of the model purse seine during hauling operation could be represented with variables such as a ratio of shooting diameter or maximum net depth and a ratio of hauling operation time. Horizontal shapes of float line and lead line were varied from a circle after shooting to an ellipse with pursing and hauling. Projected lateral shape of purse line was observed and formulated as a shape of a water drop. The cross sectional shapes of curved net from two directions were varied such as sine function or polynomial curves. Therefore, enclosed volume of a purse seine in relation to fish school behaviour can be approximated using two main variables from relevant equations.

• Journal of Hydrospace Technology
• /
• 제2권1호
• /
• pp.41-54
• /
• 1996

Sculptured surface structures such as ship hulls are traditionally formed up to the required double curved shape by line heating method. The nature of the line heating process is a transient thermal process, followed by a thermo-elastic-plastic stress field. The permanant shape is dependent on many factors involved in the process, Among them are torch speed and path, supplied heat type and amount , and plate size. Thus, the work is essentially leaded by experts with lots of experiences. However, in order to effectively improve productivity through automation, each factor should be clearly examined how much it affects the final shape. This can not be done only by experiments, but can be achieved by a mechanics-based approach. In this paper, we propose a conceptual configuration for plate forming system, and then present simulations of the line heating process with numerical data in practices and suggest a computerized process of the line heating for practical applications. The modeling of heating torch, water cooling, and the plate to be formed is proposed for the finite element analysis after the mechanics of line heating is studied. Parametric studies are given and discussed for the effects of plate thickness, torch speed and initial curvature in forming a saddle typed surface.

• 복식
• /
• 제42권
• /
• pp.223-230
• /
• 1999

Dressmaking which is defined as the process of changing two-dimensional cloth into three-dime-nsional clothes needs a lot of joining parts. Particularly sleeve needs a more curved surface than other joining parts owing to shape of the top of arms. Easing is used to control the fullness along the seam-line to create the fullness curved shape of the sleeves and it plays an important role in increasing three-dimensional constru-ction power. unfortunately sufficient data regarding effective easing conditions to increase three-dimensional construction power of sleeve are not available. Therefore the author tried to investigate the effective easing conditions to increase three-dimensional construction power of sleeve by cap height. Easing construction power of sleeve by cap height. Easing contraction made by different angles on the sleeve cap curve line previous work were examined and the effective easing conditions according to the variation of angles were determined. This study contains the following objectives. Firstly to obtain the easing contraction ratio in sleeve according to the above easing conditions. Secondly to investigate the three-dimensional construction power or sleeve by the factors of easing contraction. Thirdly to determine for each sleeve the effective easing conditions on the basis of the calcuative easing contraction ratio in the sleeve patterns by cap heights.

• 한국의류산업학회지
• /
• 제4권2호
• /
• pp.117-127
• /
• 2002

Patterns presented at baroque were mostly floral pattern. Abstract anonymous flower, tulip, Acandus leaf, pomegranate were blended with one another and had a distinct leaning toward continuation and repetition. Components of design could be classified into flower and leaf, flower and fruit, flower and circumferential ornament, bunch of flowers, flower and pot, flower and geometry, and flower and animal. Floral patterns in this era were mostly fullness type being large, simple, and having more formalized motive and were fronted with unit type and vine shape. Unit type shows reflection of baroque style which aims to present absolute unification rather than freedom, which was inherent property of baroque style, by using symmetric pattern. Vine type were unfolded with C type curved line which was main characteristics of that time and showed flowage as a whole and pliable beauty. Floral pattern was filled the whole surface of fabric, thus background of fabric can not be discerned. So, it showed extreme decorative tendency and lavishness.

• Journal of Welding and Joining
• /
• 제27권2호
• /
• pp.32-37
• /
• 2009

In shipyard, plate forming is widely used to form the ship hull plate in various shapes. Line heating method by using a flame torch is one of the major shipbuilding processes carried out by skilled workers. Since the forming characteristics depend upon their experiences in manual forming, there are much variations between products and difficulties in communication between engineers and workers. Hence, it needs to develop an automatic forming system which can not only reduce the working time and rework costs but also improve the working environment and hull forming productivity. One of the final goals of plate forming automation is to form a target shape from the initial plate automatically. For automated plate forming, it is required to determine where and how to heat on the plate. To realize this procedure, the inverse problem should be first solved and the effect of curvature shape formed at the heating path should be investigated. In this study, the inverse problem was solved by geometrical approach using the relationship between bending angle and radius of curvature of the curved shape. In addition, experiments of two-dimensional plate forming were performed with the distance-based method considering the curved bending with curvature. The result of the formed shape agreed considerably well with the target shape.