• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.6A
• /
• pp.425-433
• /
• 2011

In this study, in order to investigate the wave-induced buoyancy effects, experimental studies were conducted on pontoon-type floating structures. A series of small-scale tests with various wave cases were performed on the pontoon models. A total of four small-scale pontoon models with different lateral shapes and bottom details were fabricated and tested under the five different wave cases. Six hydraulic pressure gauges were attached to the bottom surfaces of the pontoon models and the wave-induced hydraulic pressure was measured during the tests. Finally, hydraulic pressures subjected to the bottoms of the pontoon models were compared with each other. As the results of this study, it was found that whereas the waffled bottom shape hardly influenced the wave-induced hydraulic pressure, the hybrid lateral shape significantly influenced the wave-induced hydraulic pressure subjected on the bottoms of floating structures. The air gap effects of the hybrid shape contribute to decreasing the wave-induced hydraulic pressure due to absorption of wave impact energy. Compared with box type, the hydraulic pressures of the hybrid type were about 83% at the bow, 74% at the middle, and 53% at the stern.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.329-332
• /
• 2008

The member deflection is one of the most important considerations for the serviceability evaluation of reinforced concrete structures, and the concept of the effective moment of inertia has been generally used for the estimation of beam deflections. The KCI design code adopted Branson's equation for the calculation of the effective moment of inertia, which was formulated based on the results of beam tests subjected to uniformly distributed loads. Therefore, it is worthwhile to check the applicability of the code approach on the estimation of the effective moment of inertia for the cases of beams under different loading conditions. In this study, an experimental investigation has been conducted on six beams, where primary variables were concrete compressive strengths and loading distances from supports. The test results were compared with various approaches proposed by Branson and others as well. The test results indicated that the effective moment of inertia was somewhat influenced by the moment distribution shape. Despite the different moment distribution shapes for specimens, however, the effective moment of inertia of all test beams were closely predicted by the existing methods considered in this study.

• The Bulletin of The Korean Astronomical Society
• /
• v.39 no.1
• /
• pp.56.2-56.2
• /
• 2014

We present [Fe II] 1.64 ${\mu}m$ imaging observations for jets and outflows from young stellar objects over the northern part (${\sim}24^{\prime}{\times}45^{\prime}$) of the Carina Nebula, a massive star forming region. The observations were performed with IRIS2 of Anglo-Australian Telescope and the seeing was ~1.5". Eleven jets and outflows features are detected at eight different regions, and are termed as Ionized Fe Objects (IFOs). The [Fe II] features have knotty or elongated shapes, and the detection rate of IFOs against previously identified YSOs is 1.4%. Four IFOs show anti-correlated peak intensities in [Fe II] and $H{\alpha}$, where the ratio I([Fe II])/I($H{\alpha}$) is higher for longish IFOs than for knotty IFOs. We estimate the outflow mass loss rate from the [Fe II] flux using two different methods. The jet-driving objects are identified for three IFOs (IFO-2, -4, and -7). The ratios of the outflow mass loss rate over the disk accretion rate for IFO-4 and -7 are consistent with the previously reported values ($10^{-2}-10^{+1}$), while the ratio is higher for IFO-2. This excess may result from underestimating the disk accretion rate. Other YSO physical parameters show reasonable relations or trends.

• Journal of Hydrogen and New Energy
• /
• v.25 no.1
• /
• pp.47-58
• /
• 2014

The characteristics of flame shape, laminar burning velocity, emissions and heat flux of stagnation point in premixed impinging jet flame of syngas fuel with 10% hydrogen content were experimentally investigated. Also, the adiabatic temperature and burning velocity are calculated by Chemkin package with USC-II mechanism. The equivalence ratios(0.8~5.0) and dimensionless separation distance(2.0~5.0) with fixed Reynolds number(1800) are main parameters in this work. Different flame shapes and colors were observed for different impingement conditions. The experimental results of burning velocity by flame surface area have a consistent with previous works and numerical simulation of this work. The inner flame length could be predicted with the ratio of mixture velocity and burning velocity from a simple formulation by the laminar burning velocity definition. It has been observed that the heat fluxes at stagnation point are directly affected by the flame shape including the separation distance. The emission results in impinging flame of syngas fuel show that the characteristics of $NO_x$ emission traced well with adiabatic temperature trend and CO emission due to fuel rich condition increased continuously with respect to the equivalence ratio.

• Fashion & Textile Research Journal
• /
• v.8 no.3
• /
• pp.258-268
• /
• 2006

The purpose of this study is to consider incense culture found in costume and life in forms of carrying and decoration. Here, incense for carrying and decoration is classified into two cases, using it as a costume accessory and life space. Hyangjumony, Hyangnorigae, Hyangjul, Hyangdae and Hyangseonchu were costume accessories. Hyangjumony was not only used for the royal palanguin, but also for bedroom. When Poetic Literature, and other ancient publications were reviewed in regard to incense for carrying and decoration, it was estimated that incense began to be carried for the first time before the late period of Shilla(9C). In addition, it was found that incense was not just a personal taste, but one of important gifts exchanged between states, envoys of different nations and between sovereign and subject and that incense was a necessary costume accessory for men. Types of incense for carrying and decoration used in this nation are classified into Hyangjumony, Hyangnorigae, Hyangjul and Hyangseonchu. Hyangjumony is a fabric pouch that contains incense. Hyangnorigae is Norigae whose main material is incense. Hyangjul is a string to which incense is hanged. Hyangseonchu is Seonchu whose main material is incense. Incense for carrying and decoration was based on five colors that symbolize cosmic order and harmony, of which red and purple were mostly used. Red strongly suggests expelling Yin with Yang, or exorcism. The color gives a strong impression, so it was often used to make a carried incense more decorating. Main materials of incense for carrying and decoration were gold, silver, precious stone and horsehair. They are different in characteristics, but were used appropriately for incense fragrance and decoration. Patterns mainly used for the incense had shapes of animal, plant, sipjangsaeng and letter. These were all auspicious patterns that symbolize human wishes and desires, especially individual and family happiness.

• Structural Engineering and Mechanics
• /
• v.44 no.6
• /
• pp.775-799
• /
• 2012

This work approaches the structural performance of masonry arches that have a small ratio between number of vossoirs and span length. The aim of this research is to compare and validate three different methods of analysis (funicular limit analysis F.L.A., kinematic limit analysis K.L.A. and plane stress Finite Element Analysis F.E.A.) with an experimental campaign. 18 failure tests with arches of different shapes and boundary conditions have been performed. The basic failure mechanism was the formation of enough hinges in the geometry. Nevertheless, in few cases, sliding between vossoirs also played a relevant influence. Moreover, few arches didn't reach the collapse. The FLA and KLA didn't find a solution close to the experimental values for some of the tests. The low number of vossoirs and joints become a drawback for an agreement between kinematic mechanism, equilibrium of forces and geometry constraints. FLA finds a lower bound whereas KLA finds an upper bound of the ultimate load of the arch. FEA is the most reliable and robust method and it can reproduce most of the mechanism and ultimate loads. However, special care is required in the definition of boundary conditions for FEA analysis. Scientific justification of the more suitability of numerical methods in front of classic methods at calculating arches with a few vossoirs is the main original contribution of the paper.

• Coupled systems mechanics
• /
• v.9 no.2
• /
• pp.147-161
• /
• 2020

Constructive merging of "basic" systems of different behavior creates hybrid systems. In doing so, the structural elements are grouped according to the behavior in carrying the load into a geometric order that provides sufficient load and structure functionality and optimization of the material consumption. Applicable in all materializations and logical geometric forms is a transparent system suitable for the optimization of load-bearing structures. Research by individual authors gave insight into suitable system constellations from the aspect of load capacity and the approximatemethod of estimating the participation of partialstiffnesswithin the rigidity ofthe hybrid system. The obtained terms will continue to be the basisfor our own research of the influence of variable parameters on the behavior of hybrid systemsformed of glued laminated girder and cable of different geometric shapes. Previous research has shown that by applying the strut-type hybrid systems can increase the load capacity and reduce the deformability ofthe free girder.The implemented parametric analysis pointsto the basic parameterin the behavior of these systems-the rigidity ofindividual elements and the overallstiffnessofthe system.The basic idea ofpre-stressing is that, in the load system or individual load-bearing element, prior to application of the exploitation load, artificially challenge the forcesthatshould optimize the finalsystembehaviorin the overall load. Pre-stressing is possible only if the supporting system orsystem's element possesssufficientstrength orstiffness, orreaction to the imposed forces of pre-stressing. In this paper will be presented own research of the relationship of partial stiffness of strut-type hybrid systemsofdifferentgeometric forms.Conducted parametric analysisofhybridsystemswithandwithoutpre-stressing, and on the example of the glulam-steel strut-type hybrid system under realistic conditions of change in the moisture content ofthe wooden girder,resulted in accurate expressions and diagramssuitable for application in practice.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.3
• /
• pp.299-305
• /
• 2010

In general, the flexible forming die that has been used in the flexible forming process has the identical punch size; hence, its flexibility is relatively low because the range of allowable curvature radii is limited due to the uniform punch tip radius. Hence, a conceptual design of a sectional flexible die is presented for enhancing the flexibility of the forming process. Two punches of different sizes are used to configure the arbitrary forming surface. For a forming region with a relatively large curvature radius, a large punch array block is used; on the other hand, for the forming regions with small curvature radii, a small punch block is used. The cross-sectional profiles are compared with the target shape for evaluating the effectiveness of the process. Consequently, it is confirmed that the sectional flexible die can be used along with a combination of punch blocks of different sizes for manufacturing objective surfaces of complex shapes.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.6
• /
• pp.1511-1517
• /
• 2008

The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. The magneto-rheological fluid damper, which uses such characteristics of the fluid, generates shear force due to the fluid's cohesiveness. The core can be said to determine the magneto-rheological fluid damper's performance. This study uses the finite element analysis to compare the performance of different electromagnetic forces, which are affected by the shapes of the coil, and thus to find the optimum design for the core. In addition, as a step to construct a high-efficient damper, we suggest a type of damper that can control multiple coils and compares the performance of this damper and that of the standard damper by comparing the performance of their electro-magnetic fields.

• Electrical & Electronic Materials
• /
• v.10 no.6
• /
• pp.519-527
• /
• 1997

The micro crack was occurred where the stress concentrated by the thermal stress which was induced during the cooling period after molding process or by the various reliability tests. In order to estimate the possibility of development from inside micro crack to outside fracture, the fracture toughness of EMC should be measured under the various applicable condition. But study was conducted very rarely for the above area. In order to provide a was to decide the fracture resistance of EMC (Epoxy Molding Compound) of plastic package which is produced by using transfer molding method, measuring fracture is studied. The specimens were made with various EMC material. The diverse combination of test conditions, such as different temperature, temperature /humidity conditions, different filler shapes, and post cure treatment, were tried to examine the effects of environmental condition on the fracture toughness. This study proposed a way which could improve the reliability of LOC(Lead On Chip) type package by comparing the measured $J_{IC}$ of EMC and the calculated J-integral value from FEM(Finite Element Method). The measured $K_{IC}$ value of EMC above glass transition temperature dropped sharply as the temperature increased. The $K_{IC}$ was observed to be higher before the post cure treatment than after the post cure treatment. The change of $J_{IC}$ was significant by time change. J-integral was calculated to have maximum value the angle of the direction of fracture at the lead tip was 0 degree in SOJ package and -30 degree in TSOP package. The results FEM simulation were well agreed with the results of measurement within 5% tolerance. The package crack was proved to be affected more by the structure than by the composing material of package. The structure and the composing material are the variables to reduce the package crack.ack.