• Journal of the Society of Naval Architects of Korea
• /
• v.52 no.4
• /
• pp.298-304
• /
• 2015

Shipboard equipment in naval ships should be designed to be safe under the shock load. Very high stress due to the shock load can be effectively reduced by the resilient mounts considering the mount capacity and dynamic characteristics. An optimum arrangement of resilient mount installed to absorb the shock energy is addressed to assess the safety of ship structure and shipboard equipment subjected to the shock load. Structural responses are analyzed for both frame structure supporting the shipboard equipment subject to the shock load with and without the resilient mounts. The shock absorbability of the resilient mount is evaluated by the results of structural response analysis; meanwhile, several types of shock analyses considering the arrangement of resilient mounts are carried out and the shock responses are compared to verify the effect of the arrangement. Thereafter, optimum arrangements are obtained by means of Genetic algorithm (GA) considering the different capacities of resilient mount. Stress, deformation and dynamic feature at the frame structure supporting the shipboard equipment under the shock load are also discussed in order to meet the capacity of resilient mount.

• 한국태양에너지학회:학술대회논문집
• /
• 2012.03a
• /
• pp.286-292
• /
• 2012

In recent years, building energy has received much attention and there are many support system to reduce building energy consumption. In addition, It is clear that encouraging to energy efficiency investments can be beneficial to our society, because of the energy supply instability and higher energy price in Korea. Nevertheless, ESCO business, represent the existing building energy retrofit business, hardly has not expanded in Korea. besides, in the case of existing building, it is more difficult to achieve the energy retrofit measures than new building, due to the existing buildings have attributes such as a long life and a lots of energy factor, etc. Therefore, for activate ESCO business and expand ESCO bussiness target to small-to-medium building, it is needed to optimization of retrofitting methods for existing small-to medium buildings in Korea. this research was to derive energy retrofit methods through the energy audit and analysis performed for a small-to-medium building located in Suwon, Korea.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.3
• /
• pp.804-811
• /
• 2015

The presence of responsive loads in the promising active distribution networks (ADNs) would definitely affect the power system problems such as distributed generations (DGs) studies. Hence, an optimal procedure is proposed herein which takes into account the simultaneous placement of DGs and smart meters (SMs) in ADNs. SMs are taken into consideration for the sake of successful implementing of demand response programs (DRPs) such as direct load control (DLC) with end-side consumers. Seeking to power loss minimization, the optimization procedure is tackled with genetic algorithm (GA) and tested thoroughly on 69-bus distribution test system. Different scenarios including variations in the number of DG units, adaptive power factor (APF) mode for DGs to support reactive power, and individual or simultaneous placing of DGs and SMs have been established and interrogated in depth. The obtained results certify the considerable effect of DRPs and APF mode in determining the optimal size and site of DGs to be connected in ADN resulting to the lowest value of power losses as well.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.224-227
• /
• 2008

The present study performs a test of a change in a condenser pressure on two kinds of power plants having different condenser pressure-heat rate correction curve and evaluates the results. According to a result of the test, it is confirmed that a sub-critical drum type steam power plant is optimally operated at the condenser pressure of 38㎜Hga that is designed, even during winters. On the other hand, it can be found that a supercritical once through type steam power plant operated at the condenser pressure that is reduced below a design value, that is, up to 28㎜Hga during winters is advantageous in view of turbine efficiency and is operated without a problem in facility operation such as moisture erosion, turbine vibration, etc. Also, the present study compares and reviews a condenser pressure-heat rate correction curve proposed by a manufacturer and a test value. The present study proposes optimum condenser operation pressure capable of concurrently satisfying the stable operation and efficiency improvement of the power plant facility that is operating, making it possible to support an efficient operation of a power plant.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.547-548
• /
• 2006

This study focuses on a determination of amount of Pt in the Pt/C for catalysts of polymer electrolyte membrane fuel cells (PEMFC). PEMFC offer low weight and high power density and being considered fur automotive and stationary power applications. The PEMFC behavior is quite complex is influenced by several factors, including catalysts and structure of electrode and membrane type. Catalyst of electrode is important factor for PEMFC. One of the obstacles preventing polymer electrolyte membrane fuel cells from commercialization is the high cost of noble metals to be used as catalyst, such as platinum. To effectively use these metals, they have to be will dispersed to small particles on conductive carbon supports. The optimal amount of Pt in Pt/C was investigated by using polarization curves in single cell with $H_2/O_2$ operation.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.4
• /
• pp.490-495
• /
• 2011

A slide-rail system is widely used in home appliances, furniture, mechanical rigs, and so many other applications; due to its high strength and performance for easy moving heavy objectives. In general, a pair of side slide-rails is set on both sides of a drawer to support and move it. So an unbalanced sliding motion can occur during opening and closing a drawer with pull and push force. To settle this problem, single central slide-rail having three collapsible rail-bodies was firstly proposed in this work. 'H'-beam shaped rail-body was newly designed to have enough bending and twisting strength. The experimental test showed that the proposed rail could be applied to large-size home appliances for easy moving drawer with heavy weight.

• Geomechanics and Engineering
• /
• v.23 no.1
• /
• pp.1-13
• /
• 2020

To give a solution for seismic stability of tunnel faces subjected to earthquake ground shakings, the pseudo-dynamic approach is originally introduced to analyze tunnel face stability in this study. In the light of the upper-bound theorem of limit analysis, an advanced three-dimensional mechanism combined with pseudo-dynamic approach is proposed. Based on this mechanism, the required support pressure on tunnel face can be obtained by equaling external work rates to the internal energy dissipation and implementing an optimization searching procedure related to time. Both time and space feature of seismic waves are properly accounted for in the proposed mechanism. For this reason, the proposed mechanism can better represent the actual influence of seismic motion and has a remarkable advantage in evaluating the effects of vertical seismic acceleration, soil amplification factor, seismic wave period and initial phase difference on tunnel face stability. Furthermore, the pseudo-dynamic approach is compared with the pseudo-static approach. The difference between them is illustrated from a new but understandable perspective. The comparison demonstrates that the pseudo-static approach is a conservative method but still could provide precise enough results as the pseudo-dynamic approach if the value of seismic wavelengths is large or the height of soil structures is small.

• Journal of Powder Materials
• /
• v.23 no.2
• /
• pp.149-169
• /
• 2016

Additive manufacturing (AM) is defined as the manufacture of three-dimensional tangible products by additively consolidating two-dimensional patterns layer by layer. In this review, we introduce four fundamental conceptual pillars that support AM technology: the bottom-up manufacturing factor, computer-aided manufacturing factor, distributed manufacturing factor, and eliminated manufacturing factor. All the conceptual factors work together; however, business strategy and technology optimization will vary according to the main factor that we emphasize. In parallel to the manufacturing paradigm shift toward mass personalization, manufacturing industrial ecology evolves to achieve competitiveness in economics of scope. AM technology is indeed a potent candidate manufacturing technology for satisfying volatile and customized markets. From the viewpoint of the innovation technology adoption cycle, various pros and cons of AM technology themselves prove that it is an innovative technology, in particular a disruptive innovation in manufacturing technology, as powder technology was when ingot metallurgy was dominant. Chasms related to the AM technology adoption cycle and efforts to cross the chasms are considered.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.5 no.3
• /
• pp.468-477
• /
• 2013

An automatic pipe routing system is proposed and implemented. Generally, the pipe routing design as a part of the shipbuilding process requires a considerable number of man hours due to the complexity which comes from physical and operational constraints and the crucial influence on outfitting construction productivity. Therefore, the automation of pipe routing design operations and processes has always been one of the most important goals for improvements in shipbuilding design. The proposed system is applied to a pipe routing design in the engine room space of a commercial ship. The effectiveness of this system is verified as a reasonable form of support for pipe routing design jobs. The automatic routing result of this system can serve as a good basis model in the initial stages of pipe routing design, allowing the designer to reduce their design lead time significantly. As a result, the design productivity overall can be improved with this automatic pipe routing system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.05a
• /
• pp.187-190
• /
• 2009

Recently, automotive companies have invested in vehicle weight reduction and clean car development because of oil price rises and environmental problems. In particular, USA car makers have developed the vehicle spending 1 liter per 34km complying with PNGV(Partnership for a new generation of vehicle) and Europe car makers have developed the vehicle spending 3 liters per 100km. The USA government announced "The green car policy" in order to boost production of more fuel effective cars in 2009. According to the policy, it will be restricted to sell the car which spends more than 1 liter per 14.9km by 2020. To satisfy the current situations on automotive market, hydroforming technology has widely adapted vehicle structures such as engine cradle, chassis frame, A pillar, radiator support, etc. However, automotive companies have to consider formability and performance to improve and maximize the benefit from this technology in advance of detail design. The paper deals with one of the vehicle weight reduction methods using tube hydroforming technology and platform commonality in front suspension. FEA simulation is also introduced to evaluate hydro-formability and NVH performance at the beginning of design stage which is the best way to reduce the failure cost.