• Journal of the Korean Society for Precision Engineering
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• v.19 no.11
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• pp.137-145
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• 2002

Electric vehicle body has to be subjected to uniform load and requires auxiliary equipment such as air pipe and electric wire pipe. Especially, the cross beam supports the weight of passenger and electrical equipments. a lightweight vehicle body is salutary to save operating costs and fuel consumption. Therefore this study is to perform the size and the shape optimization of crossbeam for electric vehicle using the method of topology optimization to introduce the concept of homogenization based on optimality criteria method which is efficient for the problem having the number of design variables and a few boundary condition. this provides the method to determine the optimum position and shape of circular hole in the cross beam and then can achieve the optimal design to reduce weight.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.876-883
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• 2002

Electric vehicle body has to be subjected to uniform load and requires auxiliary equipment such as air pipe and electric wire pipe. Especially, the cross beam supports the weight of passenger and electrical equipments. a lightweight vehicle body is salutary to save operating costs and fuel consumption. Therefore this study is to perform the size and the shape optimization of crossbeam fur electric vehicle using the method of topology optimization to introduce the concept of homogenization based on optimality criteria method which is efficient for the problem having the number of design variables and a few boundary condition. this provides the method to determine the optimum position and shape of circular hole in the cross beam and then can achieve the optimal design to reduce weight.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.628-636
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• 2019

In various industrial processes, piping serves as a link between unit processes and is an essential installation for internal flow. Therefore, the optimum design of the piping system is very important in terms of safety and cost, which requires the estimation of the pressure drop, flow rate, pipe size, etc. in the piping system. In this study, we developed a software that determines pressure drop, flow rate, and pipe size when any two of these design variables are known. We categorized the flows into single phase, homogeneous two phase, and separated two phase flows, and applied suitable calculation models accordingly. We also constructed a system library for the calculation of the pipe material, relative roughness, fluid property, and friction coefficients to minimize user input. We further created a costing library according to the piping material for the calculation of the investment cost of the pipe per unit length. We implemented all these functions in an integrated environment using a graphical user interface for user convenience, and C # programming language. Finally, we verified the accuracy of the software using literature data and examples from an industrial process with obtained deviations of 1% and 8.8% for the single phase and two-phase models.

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.1
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• pp.21-29
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• 2004

This paper is to study the heat transfer performance of the copper-water heat pipe with screen wicks. Recently, the semiconductor capacity of an electronic unit becomes larger, but its size becomes much smaller. As a result, a high- performance cooling system is needed. Experimental variables are inclination angles, temperatures of cooling waters and the mesh number of screen wicks. The distilled water was used as a working fluid. Based on the experimental results, when the copper-water heat pipe of 6mm diameter is used at the top heat mode, the heat transfer performance of 100 mesh 2 layers heat pipe is better than that of 150 and 200 mesh. The thermal resistance of the two layers with the 100-mesh screen was 0.7-$0.8^{\circ}C$/W.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.8
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• pp.826-831
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• 2009

The piping systems in nuclear power plant are composed of various typed pipes such as straight, elbow pipe, branch and reducer etc. The elbow is connected from straight pipe to another pipes in order to establish the complicated piping system. Elbow is one of very important components considering management of wall thinning degradation. It is however applied by various loads such as system pressure, earthquake, postulated break loading and many transient loads, which provoke simply the internal pressure, bending and torsional stress. In this study, firstly pipes in the secondary system of the nuclear power plant are classified as pipe size and type for selecting the investigating range. Next, a large number of finite element analysis considering the all typed dimensions of commercial pipe has been performed to find out the behavior of TES(twice elastic slop) plastic load of elbows, which is based on evaluation of the structural safety factor. Finally performance based structural safety factor was investigated comparing with maximum allowable load by construction code.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.161-164
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• 2000

The architecture of microprocessor for a embedded system should be one that can perform more tasks with fewer instruction codes. The machine codes that high-level language compiler produces are mainly composed of specific ones, and codes that have small size are more frequently used. Extended Instruction Set Architecture (EISC) was proposed for that reason. We have designed pipe-line system for 64 bit EISC microprocessor. function level simulator was made for verification of design and instruction set architecture was also verified by that simulator. The behavioral function of synthesized logic was verified by comparison with the results of cycle-based simulator.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.479-482
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• 2006

The most the electronic industry has recently accelerated the modularization, the miniaturization and the high integrated trend of electronics fields such as electronics components, appliances and etc., the most increasingly the heat generation problem rises. Even though the conventional cooling technologies are widely used in order to reduce the heat loads, the technologies are not easy to meet the present trends due to the fact that most of many conventional methods are relative to external form environments such as size, design and so on. With regardless of those environments, however, a heat pipe is one of the most efficient systems to improve the heat transfer performance. And then the performance of the heat pipe depends on a wick structure. Of various wick structures, sintered metal wick is known so that it has some advantages such as smaller pore size, increasing porosity as well as high reliability. In this study sintered metal wicks, thickness 0.7 mm, 0.8 mm and 0.9 mm, were manufactured as of $100{\mu}m$ copper powder to obtain the manufacturing technology of heat pipes mounted with a sintered metal wick. Furthermore, experiments for the operational performance factors such as capillary limit, thermal resistance were not only performed but also compared with a theoretical model simultaneously. Experimental results agreed with the theoretical model, and then it seems to be required to study various development processes of sintered metal wicks for the high performance of a heat pipe system.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.6
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• pp.749-757
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• 2005

The present study analyzed actual cases of designed flow estimation method and designed flow rate of sewage pipe lines. In order to examine the effects of peak-hour demand factor estimation with given daily highest peak loading, we analyzed its effects on designed flow rate with changing the peak-hour demand factor from 2.0 to 10.0. The results of this study are as follows. When reviewing the recent designs, we found that 59.4% of pipe line with 250mm and 300mm diameter, which fall under minimum allowable pipeline did not meet the minimum velocity which is specified as 0.6m/sec in design standards. The pipe line that have minimal access population or have very low slope did not satisfy the minimum velocity. In estimating the designed sewage flow, the applied daily highest peak loading and hourly highest peaking loading were the load factor for the entire population of the planned area, and for the peak loading of the initial pipes connected to a very small population, we applied the same factor as that applied to the entire area and, as a result, the hourly highest flow was underestimated. Because, in case of the initial pipes, the method of applying the same peak loading to all subject areas is highly possible to produce underestimated design flow, when estimating the designed flow of the initial pipes connected to a small population need to adopt a rational flow factor according to the size of population. For this, it is considered to investigate and analyze raw data on daily and hourly variation of sewage flow.

• Journal of the Korea Society of Computer and Information
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• v.14 no.1
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• pp.65-72
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• 2009

This study presents a structural design optimizing sizes of high-rise steel plane truss members by maximizing stiffness subjected to given volume constraints. The sizing optimum design is evaluated by using a well-known optimality criteria (OC) of gradient-based optimization methods. In typical size optimization methods, truss structures are optimized with respect to minimum weight with constraints on the value of some displacement and on the member stresses. The proposed method is an inversed size optimization process in comparisons with the typical size optimization methods since it maximizes stiffness associated with stresses or displacements subjected to volume constraints related to weight. The inversed approach is another alternative to classical size optimization methods in order to optimize members' sizes in truss structures. Numerical applications of a round shape steel pipe truss structure are studied to verify that the proposed maximum stiffness-based size optimization design is suitable for optimally developing truss members's sizes.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.6
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• pp.719-726
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• 2009

One of the alternative runoff management measures is on-site runoff mitigation, such as rainwater retention tank and infiltration facilities especially the latter that is possible to manage simultaneously runoff quality and quantity as a perspective of water-cycle. This study was conducted to develop a particle separator, inclined-pipe settling system, that could improve particle removal efficiency of road runoff as a pre-treatment device of stormwater infiltration. Solid particles larger than $100{\mu}m$ are separated by simple sedimentation; however, the significant amount of pollutants with a diameter less than $100{\mu}m$ remain in suspension. Without any treatment in that case of the runoff into infiltrate, groundwater would be deteriorated and also infiltration rate would be decreased by clogging. Therefore, we suggest optimal design parameters (inclined angle, pipe length, and surface loading rate) of inclined-pipe settling system which can be designed to effectively remove particles diameter smaller then $70{\mu}m$. Thus, the results showed TSS removal efficiency more than 80% with a particle diameter between $20{\mu}m$ and $70{\mu}m$, 100% above particle diameter $70{\mu}m$ for the inflow rate $0.018 m^3/m^2{\cdot}hr$ with pipe inclined at angle $15^{\circ}$.