• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.1 s.256
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• pp.43-49
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• 2007

A new electric coil design methodology using the notion of topology optimization is developed. The specific design problem in consideration is to find optimal coil configuration that maximizes the Lorentz force under given magnetic field. Topology optimization is usually formulated using the finite element method, but the novel feature of this method is that no such partial differential equation solver is employed during the whole optimization process. The proposed methodology allows the determination of not only coil shape but also the number of coil turns which is not possible to determine by any existing topology optimization concept and to perform single coil strand identification algorithm. The specific applications are made in the design of two-dimensional fine-pattern focusing coils of an optical pickup actuator. In this method, the concept of equivalent magnetizing current is utilized to calculate the Lorentz force, and the optimal coil configuration is obtained without any initial layout. The method is capable of generating the location and shape of turns of coil. To confirm the effectiveness of the proposed method in optical pickup applications, design problems involving multipolar permanent magnets are considered.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.1
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• pp.58-66
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• 2010

Topology design optimization is a method to determine the optimal distribution of material that yields the minimal compliance of structures, satisfying the constraint of allowable material volume. The method is easy to implement and widely used so that it becomes a powerful design tool in various disciplines. In this paper, a large-scale topology design optimization method is developed using the efficient adjoint sensitivity and optimality criteria methods. Parallel computing technique is required for the efficient topology optimization as well as the precise analysis of large-scale problems. Parallelized finite element analysis consists of the domain decomposition and the boundary communication. The preconditioned conjugate gradient method is employed for the analysis of decomposed sub-domains. The developed parallel computing method in topology optimization is utilized to determine the optimal structural layout of human powered vessel.

• Journal of Korea Multimedia Society
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• v.21 no.4
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• pp.499-512
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• 2018

The application of analytical techniques for the rational determination of problems arising from management science and corporate management. In a way that is the opposite of the repair plan that can predict accurate results is increasing utilization of the complex-based analysis methodology. In this study, we examined the application of physical space and the methodological utilization of the pedestrian model analysis that applied the simulation to the Health Checkup Center. The conclusions are as follows. First, the spatial analysis and measurement for empirical research has confirmed that the efficiency assessment through the pedestrian model simulation can lead to an objective evaluation. Second, it seems to be able to reduce the queue through a change in the number of services of the low-pressure and the hearing laboratory, the recovery room with a high proportion of male disturbances and relatively long use time. The third, the spatial density analysis and the time required to reduce the density change in comparative analysis, and the spatial layout changes, the increase in the capacity of 80 people, approximately 16 minutes to shorten the process duration.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.3
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• pp.1731-1738
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• 1969

1. For the purpose of analyzing the plan of new reclamation project and its evaluation, actual studies for the existing polders are required. 2. The variations of the salt content of soil, yields and staus of its plantation have been studied for six areas reclaimed in relatively recent years, including Kangwha, Daechon, Chopo, Eushin, Kwangyang and Chinkyo. 3. The annual yields from the project were only 52 percent in the first year as compared with kilograms per 10 a. in the Hachirogata polder in Japan. 4. Such a low productivity in the existing polders in Korea is chiefly by the high ground water table, unfavourable conditions of subdrainage in the root zone, and saline damages of existing high salt content. That is because the depth of drainage ditches is too shallow and layout distance between every drainage ditches is also too long. 5. In order to overcom such a uncertiainties, the drainagedistance suitable for these areas has been Calculated by using the Donnans formula. Applying to the formula, drainage facilities are so densie that land use capability may be decreased. 6. For the purpose of ensuring the effective desalinization and high land use capability, feasible interval to establish the culvert has been studied in accordance with both formulas of Donnan and Hoogan. 7. In order to accomplish the early desalinization in both areas of new reclamation or existing polders, the problems of internal drainages should be resolved. for this puprose in addition to the endeavour of the personnels actually engaged in such works. The actual support of the related agencies for financial assitance is required.

• International Journal of High-Rise Buildings
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• v.6 no.2
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• pp.139-147
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• 2017

Analyzing morphological evolution over a long period of time is deemed an effective way to identify problems occurring in the process of urban development, in addition to achieving a fundamental understanding of socio-cultural changes and growth rooted from the context. As far as the urban morphology is concerned, Hong Kong is characterized by its unique high-density and compact layout patterns, which have aroused the interest of a number of authors in the urban design domain. Whilst an increasing number of redevelopment projects in Hong Kong were criticized for ignoring and destroying the old urban fabric, there is a need for research to investigate the origins and changes of various urban patterns and their implications for society. By employing the theories and techniques of space syntax, this paper accordingly provides a morphological analysis based on the Wanchai District - a 'Segment-line' city, which particularly epitomizes various urban grids of Hong Kong and may have different implications for functional aspects. By axial-mapping the urban layouts of five stages of growth since 1842 and subsequently investigating their spatial and functional transformation over the past 170 years, this paper identifies a series of spatial characteristics underlying different grid patterns, as well as achieves a precise understanding of their ever changing relationship. Based on these understandings, this paper intends to provide valuable reference and guidance for upcoming spatial development in Hong Kong and other regions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.3
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• pp.5-17
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• 2000

The story of route of wet-rice diffusion to Korean peninsular is so far known only piecemeal. It is however commonly agreed that wet-rice technology may have spread the western coastal area in Korea from the lower and middle reaches of the yangzi river in China and to the Shandong peninsular and Bohai Bay region and was then transmitted overland to the area in Korea. Recently excavated three prehistoric paddy fields in Korea provide crucial evidence that helps to solve many of the important problems associated with technological diffusion. Research on the paddy field system and irrigation technology of prehistoric wet-rice has been so far especially productive in Japanese archaeology. Judging from the fact that the Yayoi wet-rice agricultural technology in Japan was transmitted by the Korean Strait from the southern part of Korea it is assumed that people in both regions may have practiced the same technology in prehistoric time. This paper examines three prehistoric paddy fields system(the Majon-ri site the Kwanchang-ri site and the Mujon-dong site) in relation to those of japanese data. The conclusions are as follows ; First early wet-rice agriculture in korea was limited by the level of technology and the size of labour. Secondly the location of field itself was restricted to the lower land and valley bottom area. Thirdly the layout of channel and field network is not very much different from the modern paddy field system.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.2
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• pp.73-79
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• 2011

This paper describes a reset-free delay-locked loop (DLL) for a memory controller application, with the aid of a hysteresis coarse lock detector. The coarse lock loop in the proposed DLL adjusts the delay between input and output clock within the pull-in range of the main loop phase detector. In addition, it monitors the main loop's lock status by dividing the input clock and counting its multiphase edges. Moreover, by using hysteresis, it controls the coarse lock range, thus reduces jitter. The proposed DLL neither suffers from harmonic lock and stuck problems nor needs an external reset or start-up signal. In a 0.13-${\mu}m$ CMOS process, post-layout simulation demonstrates that, even with a switching supply noise, the peak-to-peak jitter is less than 30 ps over the operating range of 500-1200 MHz. It occupies 0.04 $mm^2$ and dissipates 16.6 mW at 1.2 GHz.

• Korean Journal of Computational Design and Engineering
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• v.14 no.4
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• pp.242-253
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• 2009

Nowadays, manufacturing industry has been making its effort not only for productivity elevation but also for cost reduction in order to survive in the global market which is more and more challenging. In this paper, the method for planning of digital manufacturing system is proposed and door trim assembly system is determined as the subject of our research. First of all, the process sequence is generated based on the product analysis. And, the static and dynamic relationships between system components are represented using IDEF0 and UML model. The working time is estimated through the regression analysis based on MODAPTS method. According to the system configuration strategy, initial concept system layout is implemented 3D virtual environment. The problems caused by bad working motions are detected and modified through the ergonomic analysis using RULA method. According to proposed procedure, digital door trim assembly system is implemented in DLEMIA.

• International Journal of CAD/CAM
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• v.7 no.1
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• pp.41-49
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• 2007

In density-based topology optimization, 0/1 solutions are sought. Discrete topological problems are often relaxed with continuous design variables so that they can be solved using continuous mathematical programming. Although the relaxed methods are practical, grey areas appear in the optimum topologies. SIMP (Solid Isotropic Microstructures with Penalization) employs penalty schemes to suppress the intermediate densities. SRV (the Sum of the Reciprocal Variables) drives the solution to a 0/1 layout with the SRV constraint. However, both methods cannot effectively remove all the grey areas. SRV has some numerical aspects. In this work, a new scheme SIMP-SRV is proposed by combining SIMP and SRV approaches, where SIMP is employed to generate an intermediate solution to initialize the design variables and SRV is then adopted to produce the final design. The new method turned out to be very effective in conjunction with the method of moving asymptotes (MMA) when using for the stiffness topology optimization of continuum structures for minimum compliance. The numerical examples show that the hybrid technique can effectively remove all grey areas and generate stiffer optimal designs characterized with a sharper boundary in contrast to SIMP and SRV.

• Journal of information and communication convergence engineering
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• v.17 no.4
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• pp.246-254
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• 2019

This paper proposes a solution to the problem of finding a subgraph for a given instance of many terminals on a Euclidean plane. The subgraph is a tree, whose nodes represent the chosen terminals from the problem instance, and whose edges are line segments that connect two corresponding terminals. The tree is required to have the maximum number of nodes while the length is limited and is not sufficient to interconnect all the given terminals. The problem is shown to be NP-hard, and therefore a genetic algorithm is designed as an efficient practical approach. The method is suitable to various probable applications in layout optimization in areas such as communication network construction, industrial construction, and a variety of machine and electronics design problems. The proposed heuristic can be used as a general-purpose practical solver to reduce industrial costs by determining feasible interconnections among many types of components over different types of physical planes.