• Land and Housing Review
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• v.8 no.3
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• pp.181-187
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• 2017

To proactively respond to internal and external changes such as the recent demographic change and rising demand for diversified housing types, this study investigated the framed-structure free plan public house model proposed by the LH to look at the seismic performance of framed-structure apartment according to damper system use through non-linear analysis. The effectiveness thereof was also examined in terms of performance and economy. As a result, the proposed damper system application method to framed-structure free plan public house model was found to meet the performance requirements of the present earthquake-resistant design (KBC2016) and effective to apply to designs. The max response displacement and max response acceleration were compared based on the nonlinear analysis. As a result, the building with damper system showed better earthquake resistance performance than earthquake-resistant structure thanks to the damper system, although the base shear of earthquake-resistant system was reduced by 20% in design. The damper system is expected to help reduce building damage while ensuring excellent earthquake resistance performance. In addition, the framework quantities of earthquake-resistant structure and structure with damping system were compared. As a result, columns were found to reduce concrete amount by about 3.9% and rebar, by about 7.3%. Walls showed about 12.6% reduction in concrete and about 10.7% in rebar. In terms of cost, framework construction cost including formwork and foundation expenses was expected to drop by about 5~6%.

• Journal of Hydrogen and New Energy
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• v.21 no.4
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• pp.295-300
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• 2010

Metal bipolar plate applied to Polymer Electrolyte Membrane Fuel Cell is getting most attractive due to their good feasibility of mass production and low cost. But it is one of the immediate causes of performance decline because it is difficult to reduce channel pitch of metal bipolar plate. In this study, mesh was inserted in between bipolar plate and GDL to obtain uniform contact pressure without reducing channel pitch. The section measuring and performance test were carried out to confirm the mesh structure distributes contact pressure equally in reacting area. The performance of 3 type mesh structures developed in this study were higher than the normal cell at all over the current range. Especially, it showed that the mesh cell performance was increased and pressure drop was decreased with diminishing mesh gap size. The Mesh structure was more sensitive to humidification and contact pressure change than the normal cell.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.3
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• pp.297-306
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• 2003

Works were focused on back pressure characteristics of ceramic fiber filter on DPF (Diesel Particulate Filter) system and experiments were performed to select appropriate filter which can filter particulates. Filters were installed on metal -support tube which has openings for exhaust gas flow. Ceramic fiber filters with high specific surface area and adequate high temperature strength are commercially available for filtration of diesel particulates and in -situ hot regeneration. Thus, ceramic blanket and ceramic board which are used as insulating media were applied to filter and filtration apparatus was installed on exhaust gas line connected to 2.0 L diesel engine. Alternating filter structure to adapt DPF system, collection efficiency test of diesel particulates was measured. In case of ceramic blanket, pressure drop was low, caused by the destruction of soft structures. Also, particulate collection efficiency was decreased depending on loading time. In case of ceramic board, structure design was altered to reduce back pressure on DPF system. Structure design was altered to induce Z-flow by making 10 mm and 5 mm holes on the surface of media. Alteration of 5 mm hole showed that media have low back pressure but particulate collection efficiency was 77%, while 10 mm hole showed that of 90%.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.1
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• pp.28-42
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• 2017

Moisture transfer characteristics of high emotional garments are important to evaluate wear comfort. Wicking and drying measurement methods are also critical for perspiration absorption and quick dry fabric made of high functional fibers. In this study, the wicking and drying properties of high emotional fabrics made from hybrid composite yarns using CoolMax, Tencel, Bamboo staple fibers and PP. PET CoolMax filaments were also measured and analyzed according to various measuring methods. The wicking property of hybrid composite yarn fabrics by Bireck method was mostly influenced by the structure of hybrid yarns than the absorption rate of constituent fibers; however, both the hygroscopicity of fibers and the composite yarn structure affected the wicking property of the fabrics in the drop method. Concerning drying properties, the KSK 0815B method measuring distilled moisture weight was more relevant to explain the drying characteristics of hybrid yarn fabrics than the KSK 0815A method measuring the time to drying. This study revealed that the drying properties of hybrid yarn fabrics were influenced by the hygroscopicity of constituent fibers, wicking properties of constituent yarns and structure of composite yarns.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.581-586
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• 2009

This paper presents an optimal design of magnetorheological(MR) damper based on analytical methodology and finite element analysis. The proposed MR damper consists of MR valve and gas chamber. The MR valve is constrained in a specific volume and the optimization problem identifies geometric dimensions of the valve structure that maximize the pressure drop of the MR valve or damping force of the MR damper. In this work, the single-coil annular MR valve structure is considered. After describing the schematic configuration and operating principle of MR valve and damper, a quasi-static model is derived based on Bingham model of MR fluid. The magnetic circuit of the valve and damper is then analyzed by applying the Kirchoff’s law and magnetic flux conservation rule. Based on the quasi-static modeling and the magnetic circuit analysis, the optimization problem of the MR valve and damper is built. The optimal solution of the optimization problem of the MR valve structure constrained in a specific volume is then obtained and compared with the solution obtained from finite element method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.11
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• pp.1110-1118
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• 2009

This paper presents an optimal design of magnetorheological(MR) damper based on analytical methodology and finite element analysis. The proposed MR damper consists of MR valve and gas chamber. The MR valve is constrained in a specific volume and the optimization problem identifies geometric dimensions of the valve structure that maximize the pressure drop of the MR valve or damping force of the MR damper. In this work, the single-coil annular MR valve structure is considered. After describing the schematic configuration and operating principle of MR valve and damper, a quasi-static model is derived based on Bingham model of MR fluid. The magnetic circuit of the valve and damper is then analyzed by applying the Kirchoff' s law and magnetic flux conservation rule. Based on the quasi-static modeling and the magnetic circuit analysis, the optimization problem of the MR valve and damper is built. The optimal solution of the optimization problem of the MR valve structure constrained in a specific volume is then obtained and compared with the solution obtained from finite element method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.4
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• pp.247-252
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• 2012

IGBT (insulated gate bipolar transistor) has been widely used around the power industry as it has good switching performance and its excellent conductance. In order to reduce power loss during switch turn-on state, it is essential to reduce its resistance. However, trade off relationship between breakdown voltage and device conductance is the greatest obstacle on the way of improvement. Floating island structure is one of the solutions. Still, under optimized device condition for the best performance, improvement rate is negligible. Therefore, this paper suggests adding trench gate on floating island structure to eliminate JFET (junction field effect transistor) area to reduce resistance and activate floating island effect. Experimental result by 2D simulation using TCAD, shows 20% improvement of turn-on state voltage drop.

• Fire Science and Engineering
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• v.17 no.3
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• pp.20-25
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• 2003

Measurements with filaments and thermocouples and computations with Oppdif and FDS were carried out to investigate the impact of flame strain, agent addition, and buoyancy on the structure and extinction of nonpremixed counterflow flames. Measurements through 2.2 s drop tests in microgravity conditions and experiments in normal gravity conditions were compared with the results of computations. For the global strain rates 7 s$^{-1}$ through 100 s$^{-1}$ , the turning point behavior in the critical nitrogen concentration at O-g was confirmed. The effects of buoyancy, that is, changes in the flame curvature and thickness were also confirmed by the computations with FDS. There was agreement in the peak flame temperature and its position between the computations and the measurements in the near extinction methane/air diffusion flames in microgravity.

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.1022-1035
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• 2016

A double-tube once-through steam generator (DOTSG) consisting of an outer straight tube and an inner helical tube is studied in this work. First, the structure of the DOTSG is optimized by considering two different objective functions. The tube length and the total pressure drop are considered as the first and second objective functions, respectively. Because the DOTSG is divided into the subcooled, boiling, and superheated sections according to the different secondary fluid states, the pitches in the three sections are defined as the optimization variables. A multi-objective optimization model is established and solved by particle swarm optimization. The optimization pitch is small in the subcooled region and superheated region, and large in the boiling region. Considering the availability of the optimum structure at power levels below 100% full power, we propose a new operating scheme that can fix the boundaries between the three heat-transfer sections. The operation scheme is proposed on the basis of data for full power, and the operation parameters are calculated at low power level. The primary inlet and outlet temperatures, as well as flow rate and secondary outlet temperature are changed according to the operation procedure.

• Korean Institute of Interior Design Journal
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• v.16 no.3 s.62
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• pp.119-129
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• 2007

This study illustrates a prototype proposal and its evaluation for the development of floor plans in the condominium housing remodeling. For this I evaluated the survey of the residents of the 'K' town in Joonge-dong, Nowon-gu, Seoul, against the proposal which was developed based on the resident's pre-survey. The result includes that the residents' preference for community actions such as the removal of fences which are reviewed as negative, whereas the introduction of a fitness center and community facilities in the library are reviewed as positive. The residents preferred the open space by the piloti structure, although which is the wall column structure, where they anticipated a rest area, sports facilities, and bicycle drop-off spots. The sidewall proposal in the main building and the full use of the roof floor were underestimated in terms of design concept. The research also illustrated the residents' desired space planning options, those tending to use of space 'B type', personalization 'C type' and spatial size 'A type'. Residents responded positively to the introduction of the 'Alpha' space in which two households share one space that could be used for multiple purposes such as a rest area, an environment-friendly garden, and hobby room, etc, and also there is another possibility it plays an important role to the sociality in community.