• Structural Engineering and Mechanics
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• v.53 no.4
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• pp.833-845
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• 2015

Natural frequencies of the structural systems should be far away from the excitation frequency in order to avoid or reduce the destructive effects of dynamic loads on structures. To accomplish this goal, a structural optimization on size and shape has been performed considering frequency constraints. Such an optimization problem has highly nonlinear property. Thus, the quality of the solution is not independent of the optimization technique to be applied. This study presents the performance evaluation of the recently proposed meta-heuristic algorithm called Teaching Learning Based Optimization (TLBO) as an optimization engine in the weight optimization of the truss structures under frequency constraints. Some examples regarding the optimization of trusses on shape and size with frequency constraints are solved. Also, the results obtained are tabulated for comparison. The results demonstrated that the performance of the TLBO is satisfactory. Additionally, TLBO is better than other methods in some cases.

• Journal of Welding and Joining
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• v.14 no.1
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• pp.82-91
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• 1996

The maximum butt-joint gap size in $CO_2$ laser beam welding of SAPH steel plates with different thicknesses and its bending formability were studied. In the range of the gap size$\geq$0.1mm, the optimal butt welding speed was faster than that of no gap (air gap) condition. This behaviour was independent on the difference of thickness at any combination. Also, the allowable gap size in steel plates with different thicknesses was larger than with same thicknesses. In the range of $T/T_0$(bead shape) $\geq$ 0.8, good bending formability was obtained at any combination of thickness. The formability was improved by reducing the hardness in weld bead using pre-heating process. Finally, FEM result of the laser beam welded underframe with different thicknesses was compared to that of the conventional spot welded underframe.

• Journal of the Korean housing association
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• v.13 no.3
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• pp.45-53
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• 2002

The purpose of this study is to examine the characteristics of unit plans in the high-rise mixed-use condominium and to provide the data fur architectural planning and design. The tools of statistical analysis are frequency, percentage, mean, cross-tab, and correlation. The results of this study are as fellows; The most frequently found shape of unit is a deformed polygon. The common rooms in housing units are dressing room, powder room, offset-kitchen, family room, passage, hallway, and foyer. The specially prepared spaces are wash room, home bar, independent porch, and garden. As to room size and area ratio in a dwelling unit, those of living room are biggest and highest irrespective of unit size. As the floor area of unit increases, does the size of each room and space but the area ratio of each room decreases. This research is made to develop an Apartment Information System. This integrated information system is to be designed to provide residents of high-rise mixed-use condominiums with convenient, economical, and safe life.

• Korean Management Science Review
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• v.31 no.4
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• pp.135-150
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• 2014

This paper analyzes the operational efficiency of 91 individual retail stores in Seoul by a two-step procedure. In the first step, a data envelopment analysis (DEA) model is used to identify the efficiency scores. Three inputs (store size, number of items, and number of employees) and two outputs (sales and number of customers) are used for the efficiency measurement. In the second step, a Tobit regression model is used to identify the drivers of efficiency. DEA efficiency scores are used to test hypotheses on the impact of five independent variables, namely store age, number of items per store size, number of items per employee, trade area index, and number of competitors. Results of the Tobit analysis show that number of items per store size, number of items per employee, and number of competitors play a significant role in influencing the operational efficiency of retail stores. Managerial implications of the study are discussed.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.89-93
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• 1994

Effects of density, inner-stress, and grain size on B-H hysteresis loop properties of Mg-ferrite were investigated. As the sintered bulk density increase, coercive force($H_c$) decreasand squareness ratio increase. Coercive force was very dependent on inner-stress in sintered body, so coercive force increase from 1.95[Oe] to 4.35[Oe] when inner stress present in bulk, however, the squareness ratio was almost not changed Coercive force and squareness ratio were independent on grain size of sintered body which is between 6-11[$\mu\textrm{m}$]

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.228-231
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• 1999

This paper describes the design and implementation of an application specific instruction-set processor developed for embedded DSP applications. The instruction-set has an uniform size of 16 bits, and supports 3 types of instructions: Primitive, Complex, and Specific. To reduce code size and cycle count we introduce complex instructions that can be selected according to the application under consideration, which leads to 50% code size reduction maximally. The processor has two independent data memories to double the data throughput and the address space. The processor is synthesized by 0.6$\mu$m single-poly double-metal technology. Critical path simulation shows that the maximum frequency is 110MHz and total gate count is 132, 000.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.303-311
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• 1999

The cooperation between industry and universities has actively been established for technical development using available manpower and facilities. However, it is necessary under International Monetary Fund era that cooperation among industry, universities, and government should be accomplished to increase export for small and medium size industry. In this paper, we regard the cooperation system among three independent organizations and pursue to improve the quality and productivity of the system. We propose some suggestions to grow the small and medium size industry toward export and introduce a case study.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.3
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• pp.67-75
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• 1993

In many practical applications of systolic array, it is common that the problem size(n) is larger than the array size(M). In this case, the problem has to be partitioned into block to fit into the array before it is processed. This paper presents a problem partition method for dynamic programming and 2-dimensional systolic array suitable for it. Designed array has two types of array configur-ation for processing the partitioned problem. The queue is designed for storing and recirculating the intermediate results in the correct location and time. The number of processing elements and queues required are M(3M+1)/2, 4M respectively. The total processing time is 2(M+1)+(n+10M+3)(n/M-1)(n/M-1)/6.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.6
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• pp.1343-1349
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• 1988

In this study, it is investigated for the effects of stress ratio and grain size on fatigue crack growth behavior and crack closure, in ferrite-martensite dual phase steels. The results obtained are as follows ; .DELTA. $K_{th}$ is independent of the ferrite grain size, but decreases with increasing stress ratio. The relation between .DELTA. $K_{th}$ and stress ratio R is as follows : .DELTA. $K_{th}$ =15.1(1-0.95R). But (.DELTA. $K_{eff}$)$_{th}$ in terms of crack closure is approximately 2.5 MPa.root.m. Also, variation of the degree of crack deflection to crack tip opening displacement at the minimum load is considered as a parameter of crack closure.e.e.

• Journal of Navigation and Port Research
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• v.43 no.2
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• pp.134-141
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• 2019

The objective of this study was to establish whether global macroeconomic indicators affect the profitability of Korean shipping companies by using panel regression analysis. OROA (operating return on assets) and ROA (ratio of net profit to assets) were selected as proxy variables for profitability. OROA and ROA were used as dependent variables. The world GDP growth rate, interest rate, exchange rate, stock index, bunker price, freight, demand and supply of the world shipping market were set as independent variables. The size of the firm was added to the control variable. For small-sized firms, OROA was not affect by macroeconomic indicators. However, ROA was affected by variables such as interest rates, bunker prices, and size of firms. For medium-sized firms, OROA was affected by demand, supply, GDP, freight, and asset variables. However, macroeconomic indicators did not affect ROA. For large-sized firms, freight, GDP, and stock index (SCI; Shanghai Composite Index) have an effect on OROA. ROA was analyzed to be influenced by bunker price and SCI.