• Journal of Korean Association for Spatial Structures
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• v.9 no.3
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• pp.75-82
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• 2009

This paper investigates the variation of post-buckling behaviours of spatial structures after sizing optimization with linear assumptions. The mathematical programming technique is used to produce the optimum member size of spatial structures against external load. Total weight of structure is considered as the objective function to be minimized and the displacement occurred at loading point and member stresses of structures are used as the constraint functions. The finite difference method is used to calculate the design sensitivity of objective function with respect to design variables. The post-buckling analysis carried out by using the geometrically nonlinear finite element analysis code ISADO-GN. It is found to be that there is a huge difference between the post buckling behaviours of the initial and optimized structures. Therefore, the stability of optimized spatial structures with linear assumption should be throughly checked by appropriate nonlinear analysis techniques. Finally, the present numerical results are provided as benchmark test suite for future study of large spatial structures.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.205-212
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• 2004

In this paper the design of a 1-[KVA] fuel cell powered line-interactive UPS system employing modular (fuel cell & DC/DC converter) blocks is proposed. The proposed system employs the two fuel cell modules along with suitable DC/DC converters and these modules share the DC-Link of the DC/AC inverter. A supercapacitor module is also employed to compensate for the instantaneous power fluctuations and to overcome the slow dynamics of the fuel processor. The energy stored in the supercapacitor can also be utilized to handle the overload conditions for a short time period. Due to the absence of batteries, the system satisfies the demand for an environmentally friendly and dean source of the energy. A complete design example illustrating the amount of hydrogen storage required for 1hr power outage, and sizing of supercacpacitor for transient load demand is presented for a 1-[KVA] UPS.

• Structural Engineering and Mechanics
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• v.82 no.5
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• pp.595-609
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• 2022

Prestressed composite steel-concrete beams are still a technology restricted to repair sites of large-scale structures and spans. One of the reasons for that is the absence of standard frameworks and publications regarding their design and implementation. In addition, the primary normative codes do not address this subject directly, which might be related to a scarcity of papers indicating methods of design that would align the two technics, composite beams and external prestressing. In this context, this paper proposes methods to analyze the sizing of prestressed composite beams submitted to pre-tension and post-tension with a straight or polynomial layout cable. This inquiry inspected a hundred and twenty models of prestressed composite beams according to its prestressing technology and the eccentricity and value of the prestressing force. The evaluation also included the ratio between span and height of the steel profile, thickness and typology of the concrete slab, and layout of the prestressing cables. As for the results, it was observed that the eccentricity of the prestressing force doesn't significantly influence the bending resistance. In prestressed composite beams subjected to a sagging moment, the ratio L/d can reach 35 and 30 for steel-concrete composite slabs and solid concrete slabs, respectively. Considering the negative bending moment resistance, the value of the L/d ratio must be less than or equal to 25, regardless of the type of slab. When it comes to the value of the prestressing force, a variation greater than 10% causes a 2.6% increase in the positive bending moment resistance and a 4% decrease in the negative bending moment resistance. The pre-tensioned composite beams showed a superior response to flexural-compression and excessive compression limit states than the post-tensioned ones.

• Journal of IKEEE
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• v.16 no.3
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• pp.265-273
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• 2012

Data stability and leakage power dissipation have become a critical issue in scaled SRAM design. In this paper, an advanced 8T SRAM cell improving the read and write stability of data storage elements as well as reducing the leakage current in the idle mode is presented. During the read operation, the bit-cell keeps the noise-vulnerable data 'low' node voltage close to the ground level, and thus producing near-ideal voltage transfer characteristics essential for robust read functionality. In the write operation, a negative bias on the cell facilitates to change the contents of the bit. Unlike the conventional 6T cell, there is no conflicting read and write requirement on sizing the transistors. In the standby mode, the built-in stacked device in the 8T cell reduces the leakage current significantly. The 8T SRAM cell implemented in a 130 nm CMOS technology demonstrates almost 100 % higher read stability while bearing 20 % better write-ability at 1.2 V typical condition, and a reduction by 45 % in leakage power consumption compared to the standard 6T cell. The stability enhancement and leakage power reduction provided with the proposed bit-cell are confirmed under process, voltage and temperature variations.

• Membrane Journal
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• v.28 no.2
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• pp.90-95
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• 2018

A process design was performed for a removal of acid gases using membrane-absorption hybrid system in LNG-FPSO. Commercial process simulator Promax version 4.0 was utilized for comparing acid gases removal capabilities of amine absorption process and hybrid process. Simulation results show hybrid process could be small amine solvent circulate rate, energy consumption, equipment sizing compared to typical amine absorption process. As a result, hybrid process which is small footprint and energy saving process may be a good solution for the pre-treatment of natural gas in LNG-FPSO.

• Journal of the Korean Society of Clothing and Textiles
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• v.40 no.5
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• pp.894-909
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• 2016

This study analyzed a somatotype that was more suitable to a virtual fitting model and to improve the reality of a virtual model size. We analyzed 1,868 women 18-59 years old from the 6th Size Korea data. First, factor analysis was done for abstracting new criteria for dividing the somatotype; subsequently, we selected the waist height proportion to stature (body proportion) and drop (torso shape). Next, the cluster analysis was done with these criteria and 7 body proportion types and 11 torso shapes were distinguished. A virtual model size for the most common somatotype was also developed by a regression analysis of constituting sizes of each factor that was compared with body sizes well as with Clo's virtual model size. The model of this research showed a high similarity in sizes with body as well as improved better realisty than the Clo model which presented size problems such as longer limbs, bigger bust, smaller waist and a smaller arm circumference than the real body.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.3
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• pp.35-43
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• 2017

Research for solar-powered high altitude long endurance(HALE) UAV was conducted by Korea Aerospace Research Institute(KARI), and the EAV-3 with 19.5m wing span was developed. For HALE flight, aircraft should be lightly designed. Especially, airframe structure that accounts for a large portion of the total weight of aircraft should be lightweight. In this paper, development process of airframe structure for solar-powered HALE UAV, EAV-3, is described briefly. Domestic developed T-800 grade CFRP(Carbon Fiber Reinforced Plastic) composite material with high modulus and strength was used to design main load carrying structures. Flightloads analysis that takes into account large structural deformation was carried out. Stress and flutter analyses for airframe structure sizing were conducted. Static strength test for main wing and aircraft ground vibration test were conducted successfully and structural integrity was secured.

• Journal of the Korean Home Economics Association
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• v.44 no.4 s.218
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• pp.123-131
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• 2006

The goal of this research was to investigate the actual wearing conditions of dementia inpatients in order to improve their clothes. The development of comfortable, functional and well-designed clothing for dementia inpatients can improve their clinical care environment and also provide dementia inpatients and their caregivers with a promoted quality of life. The data were collected through field research and interview survey on the inpatient's clothing being used at 10 dementia hospitals and 11 dementia nursing care facilities. The results were as follows, First, the uniforms of light dementia inpatients were the pajamas styles those of the general inpatient's uniforms. The uniforms of severe dementia inpatients were jump suits or pajamas styles. Second, the top styles of pajamas were shirts of front opening style with buttons, round neckline, full length sleeves and over armholes. Their bottoms were the pants of no opening style with elastic band and full length. The design of the jump suits had back and under opening styles with zippers. Third, dementia inpatient clothes have to be improved in the areas of sizing systems, structure for putting on and taking off, fasteners and open styles and clothing material, as well as the aesthetic approach.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.55-61
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• 2012

The structure of winch brake disk was successfully designed and developed based on sizing optimization. In this research, static analysis was performed by commercial software ANSYS v12.0. To simulate the working process of disk brake, the real properties of materials and working conditions were considered. Based on the results of the static structural analysis, the existing designs of the brake discs were optimized. Among existing designs, there are three cases that have achieved an efficient light weight around 200g. As a result, the optimized weight of each case was 3.41kg, 3.42kg, and 3.44kg, respectively. Finally, through prototyping and performance testing, the stability of the optimized brake disc was verified. Although, this free-fall winch brake disk had been developed in design and evaluation techniques, more detailed plans for developing the disk brake structure were also proposed as a further study based on this research.

• Fashion & Textile Research Journal
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• v.18 no.4
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• pp.489-497
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• 2016

The purpose of this study is to most appropriately develop maternity wear according to the preferences of specific age groups of pregnant women. The specific age groups were women in their twenties, early thirties, and late thirties. This survey was conducted in the metropolitan area around Seoul, South Korea through a questionnaire given to 150 pregnant women. The study found that pregnant women purchased significantly cheaper clothes after their pregnancy than before. The participants responded that they mostly bought clothes using the Internet, but they also reported many instances of returning the clothes due to fit and sizing. It was shown that women in their twenties tended to consider the price, design, and activity more than women in their thirties when purchasing maternity wear. The study showed that pregnant women tended to wear maternity wear from early in the pregnancy-preferring leggings, one-piece dresses, pants, shirts, briefs, and bras with the girdle on the outside. More women in their late thirties purchased maternity support belts than younger age groups. In any case, in purchasing maternity wear, clothing features that the respondents focused on were comfort, functionality, fit, the covering of their body changes, and fashion. Still, many respondents 35 years and older reported more interest in safety rather than fashion in comparison to the responses of respondents under the age of 35.