• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.719-727
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• 2021

In the field of architecture, retractable devices capable of responding flexibly to the environment have been applied widely to large structures. Among these devices, the aesthetically pleasing retractable membrane is lightweight so that the membrane can be opened easily using only a traction device. On the other hand, because the towed membrane moves as it is connected to the main cable by a trolley, the number of trolleys needed increases in proportion to the roof's area. This study proposes an optimal model for an open-type trolley (OTT), which is used widely in these devices, using topology optimization. The analysis used the ANSYS program. A new model was proposed based on the results and reviewed through the feedback. Through this process, it was possible to develop a prototype with increased durability and reduced weight. For OTT, optimization was performed based on static analysis and the boundary conditions, so three prototypes were designed. A comparison of the proposed trolley with the conventional one under the same conditions revealed an up to 71.04% decrease in volume while the yield-strength reached 8.67 to 11.43%. In conclusion, the optimal trolley proposed was found to be reliable in terms of economy and stability.

• Journal of Korean Association for Spatial Structures
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• v.7 no.3 s.25
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• pp.57-66
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• 2007

The membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation. In shape finding, membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses because of its initial unstable state, and happen large deformation phenomenon. Therefore, in this paper, we investigate the convergence of solution and the speed according to the control variables and the method of shape analysis.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.3
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• pp.71-80
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• 2016

The component-based modeling framework for agricultural water-resources management (COMFARM) is a user-friendly, highly interoperable, lightweight modeling framework that supports the development of watershed-specific domain components. The objective of this study was to evaluate the suitability of the COMFARM for the design and creation of a component-based modeling system of agricultural reservoir watersheds. A case study that focused on a particular modeling system was conducted on a watershed that includes the Daehwa and Dangwol serial irrigation reservoirs. The hydrologic modeling system for the study area was constructed with linkable components, including the modified Tank, an agricultural water supply and drainage model, and a reservoir water balance model. The model parameters were each calibrated for two years, based on observed reservoir water levels. The simulated results were in good agreement with the observed data. In addition, the applicability of the COMFARM was evaluated for regions where reservoir outflows, including not only spillway release but also return flow by irrigation water supply, substantially affect the downstream river discharge. The COMFARM could help to develop effective water-management measures by allowing the construction of a modeling system and evaluation of multiple operational scenarios customized for a specific watershed.

• The Journal of Society for e-Business Studies
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• v.8 no.3
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• pp.1-16
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• 2003

XML(Extensible Markup Language) is an emerging standard for data representation and exchange in e-commerce and internet-based information. However, to realize this potential, it is necessary to be able to extract structured data from XML documents and store it in a database, as well as to generate XML documents from data extracted from a database. Although many DBMS vendors are scrambling to extend their products to handle XML, there is a need for a lightweight, DBMS and platform-independent XML middleware as well. In this paper we describe such a XML2RDB middleware, that solves the following problems . generating relational schema from XML DTDs for storage of XML documents, importing data from XML documents into relational tables, creating XML documents according to a XMLQL(XML Query Language) from data extracted from a database.

• Journal of IKEEE
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• v.22 no.1
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• pp.38-45
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• 2018

An integrated cryptographic processor that efficiently integrates ARIA, AES block ciphers and Whirlpool hash function into a single hardware architecture is described. Based on the algorithm characteristics of ARIA, AES, and Whirlpool, we optimized the design so that the hardware resources of the substitution layer and the diffusion layer were shared. The round block was designed to operate in a time-division manner for the round transformation and the round key expansion of the Whirlpool hash, resulting in a lightweight hardware implementation. The hardware operation of the integrated ARIA-AES-Whirlpool crypto-processor was verified by Virtex5 FPGA implementation, and it occupied 68,531 gate equivalents (GEs) with a 0.18um CMOS cell library. When operating at 80 MHz clock frequency, it was estimated that the throughputs of ARIA, AES block ciphers, and Whirlpool hash were 602~787 Mbps, 682~930 Mbps, and 512 Mbps, respectively.

• Journal of Hydrogen and New Energy
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• v.13 no.4
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• pp.270-278
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• 2002

Mg and Mg alloys are attractive hydrogen storage materials because of their lightweight and high absorption capacity. Their range of applications could be further extended if their hydrogenation properties and degradation behavior could be improved, The main emphasis of this study was to find an economic manufacturing method for Mg-Ti-Ni-H systems, and to investigate their hydrogenation properties, In order to examine hydrogenation behavior, a Sieverts type automatic pressure-composition-isotherm(PCI) apparatus was used and the experiments were performed at 423, 473, 523, 573, 623 and 673K. The results of thermogravimetric analysis(TGA) reveal that the absorbed hydrogen contents are around 2.5 wt% for ($Mg_9Ti_1$)-10 wt% Ni. With increased Ni content, the absorbed hydrogen content decreases to 1.7 wt%, whereas the dehydriding starting temperatures are lowered by some 70-100K. The results of PCI on ($Mg_9Ti_1$)-20 wt% Ni show that its hydrogen capacity is around 5.3 wt% and its reversible capacity and plateau pressure are also excellent at 523K and 573K. In addition, the reaction enthalpy, $\Delta$HD.plateau, is $30.6{\pm}5.7kJ/molH_2$.

• Composites Research
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• v.27 no.2
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• pp.47-51
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• 2014

The purpose of the present study is to develop lightweight and simple smart actuators in order to replace conventional hydraulic/pneumatic actuators, and to apply the developed actuators to the actuation systems of a small unmanned air vehicle. This research describes the procedures of design, manufacturing of the piezo-composite actuator, and the performance evaluation. From the test results of the developed devices, we found the possibility of piezo-composite actuator could be used as a control surface of a small UAV system. We have designed and manufactured two kinds of piezo-composite actuators, unimorph actuator and bimorph actuator. The manufactured actuators were evaluated through the performance testes. It was found that the bimorph type actuator showed more linear angle change for the same excitation voltage variation than unimorph type. It is expected that piezo-composite actuator has a possibility to be used not only as a control surface of small unmanned flying vehicle but also as a control surface actuator of a guided missile fin through the miniaturization of power supply and control system.

• Composites Research
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• v.33 no.5
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• pp.262-267
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• 2020

With increasing demands for high-speed machining and lightweight design of machine tools, increasing likeliness of generation of machine tool spindle vibrations has become an important issue. Spindle vibration has a significant impact on the surface finish of the workpiece in ultra-precision machining. It is necessary to resolve the machine tool spindle vibration in various machining processes to improve machining accuracy. In this paper, a TiC-SKH51 metal-matrix composite was used to suppress the vibration of the machine tool spindle. To confirm the dynamic characteristic of the TiC-SKH51 composite, impact hammer tests were conducted. After verifying the reliability of a finite element analysis (FEA) by comparing the results of the impact hammer test with the modal analysis using FEA, the analysis of the machine tool spindle model was performed. The FEA results show that the TiC-SKH51 composite applied machine tool spindle can be utilized to suppress the vibration generation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3
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• pp.388-393
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• 2013

Carbon fiber reinforced plastic (CFRP) has many desirable qualities, including being lightweight and very strong. These characteristics have led to its use in applications ranging from small consumer products to vehicles. Circular and square CFRP members were fabricated using 8ply unidirectional prepreg sheets stacked at different angles ($[+15^{\circ}/-15^{\circ}]_4$, $[+45^{\circ}/-45^{\circ}]_4$ and $[90]_8$, where $0^{\circ}$ coincides with the axis of the member). Based on the collapse characteristics of a CFRP circular member, the collapse characteristics and energy absorption capability were analyzed. Impact collapse tests were carried out for each section member. In this study, the impact energies at crossheads speeds of 5.52 m/s, 5.14 m/s and 4.57 m/s were 611.52 J, 529.2 J and 419.44 J (circular member) 2.16 m/s, 1.85 m/s and 1.67 m/s are 372.4 J, 274.4 J and 223.44 J (square member). The purpose is to experimentally examine the absorption behavior and evaluation the strength in relation to changes in the stacking configuration when the CFRP circular members with different stacking configurations were exposed to various impact velocities. In addition, the dynamic characteristics were considered.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.5 s.164
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• pp.742-752
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• 2007

The purpose of this study is the image of clothing according to the change of the dots' size was analyzed and its influence on the formation of the image of polka dots clothing was investigated. White waterdrop patterns were designed on the 12 kinds of black texture using Photoshop and CAD program in regular arrangement of diamond figure, composed of white waterdrop(0.5cm, 1.0cm, 1.5cm and 2cm in diameter) and interval(diameter : interval-1 : 1, 1 : 2, 1 : 4). Applying above specification, the photograph stimulus of 12 kinds of X-line one-piece dress with wide square neckline and without sleeve or detailed ornament was presented on a screen in the same size as when putting it on. The image of polka dots clothes was investigated by questionnaire survey. The object of the study was 320 females aged between 16 and 29. Factor analysis, one-way ANOVA, $Scheff\acute{e}$ verification and two-way ANOVA using SPSS 10.0 were carried out for data analysis. Followings are the results: 1) The image of polka dots clothing consists of 4 factors as aesthetics, brevity, dynamism and lightweight. 2) The size of the dot has a great influence on the formation of the image of polka dots clothing. 3) The evaluations of the image of polka dots clothing were different depending on the age and physical image, the personal characteristics of the object of investigation.