• 전산구조공학
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• 제8권4호
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• pp.99-106
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• 1995

구조물의 최적설계에 대한 일반적인 개념이 제시되며 Gradient Projection법과 설계민감도 해석을 사용한 최적화 알고리즘이 논의된다. 6층 평면 철골 구조물의 최소무게설계의 예를 통해 이 알고리즘의 적용을 예시한다. 시스템 전체의 비용분석뿐만 아니라 임계 비용 및 설계민감도 해석과 같은 이 알고리즘의 장점에 관하여 설명한다.

• Smart Structures and Systems
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• 제14권4호
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• pp.541-558
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• 2014

This paper proposes a new design of shape memory alloy (SMA) wire actuated gripper for open mode operation. SMA can generate smooth muscle movements during actuation which make them potentially good contenders in designing grippers. The principle of the shape memory alloy gripper is to convert the linear displacement of the SMA wire actuator into the angular displacement of the gripping jaw. Steady state analysis is performed to design the wire diameter of the bias spring for a known SMA wire. The gripper is designed to open about an angle of $22.5^{\circ}$ when actuated using pulsating electric current from a constant current source. The safe operating power range of the gripper is determined and verified theoretically. Experimental evaluation for the uncontrolled gripper showed a rotation of $19.97^{\circ}$. Forced cooling techniques were employed to speed up the cooling process. The gripper is simple and robust in design (single movable jaw), easy to fabricate, low cost, and exhibits wide handling capabilities like longer object handling time and handling wide sizes of objects with minimum utilization of power since power is required only to grasp and release operations.

• 한국농공학회지
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• 제30권2호
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• pp.67-81
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• 1988

The purpose of the present study is to set up an efficient optimum design method for the large-scale reinforced concrete cylindrical shell structures like intake tower of reservoir and to establish a solid foundation for the automatic optimum structural design combined with finite element analysis. The major design variables are the dimensions and steel areas of each member of the structures. The construction cost which is composed of the concrete, steel, and form work costs, respectively, is taken as the objective function. The constraint equations for the design of intake-tower are derived on the basis of the working stress design method. The corresponding design guides including the standard specification for concrete structures have been also employed in deraving the constraint conditions. The present nonlinear optimization problem is solved by SUMT method. The reinforced concrete intake-tower is decomposed into three major substructures. The optimization is then conducted for both the whole structure and the substructures. The following conclusions can be drawn from the present study. 1. The basis of automatic optimum design of reinforced concrete cylindrical shell structures which is combined with finite element analysis was established. 2. The efficient optimization algorithms which can execute the automatic optimum desigh of reinforced concrete intake-tower based on the working stress design method were developed. 3. Since the objective function and design variables were converged to their optimum values within the first or second iteration, the optImization algorithms developed in this study seem to be efficient and stable. 4. The difference in construction cost between the optimum designs with the substructures and with the entire structure was found to be small and thus the optimum design with the substructures,rnay conveniently be used in practical design. 5. The major active constraints of each structural member were found to be the tensile stress insteel for salb, the minimum lonitudinal steel ratio constraints for tower body and the shearing stress in concrete, tensile stress in steel and maximum eccentricityconstraints for footing, respectively. 6. The computer program develope in the present study can be effectively used even by an unexperienced designer for the optimum design of reinforced concrete intake-tower.

• 한국멀티미디어학회논문지
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• 제11권1호
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• pp.44-52
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• 2008

본 논문은 Grade Of Services Steiner Minimum Tree 문제 해결을 위한 우리의 휴리스틱의 개선에 관한 것이다. 이 문제는 멀티미디어 통신에서 응용할 수 있는 여러 등급의 서비스를 각기 제공할 수 있는 네트워크를 설계하는데 적용할 수 있다. NP-Hard 문제로 알려진 이 문제는 주어진 터미널 노드를 모두 연결하고 G-Condition을 만족하는 네트워크 중에서 가장 적은 구축비용을 만족하는 네트워크를 찾는 것이다. 우리의 이전 연구에서 이 문제를 해결하기 위한 몇 개의 휴리스틱을 제안했다. 본 논문에서는 이 휴리스틱의 성능을 개선하기 위해 G-Condition 검사 순서 및 방법에 대한 전략을 제안한다. 이 전략을 반영한 개선된 휴리스틱들에 관한 실험은 이전 것들에 비해 평균적으로 실행시간은 71.9%, 스타이너 포인트의 수는 28.9%, 네트워크 구축비용은 1.1%의 감소의 결과를 얻었다.

• 대한조선학회논문집
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• 제41권6호
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• pp.120-125
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• 2004

There are very few numbers of 115K FPP (Fixed Pitch Propulsion) Tankers for the Baltic ice class IA because the minimum power requirement of FMA (Finish- Swedish Maritime Association) needs quite large engine power and the 40 m Beam is out of calculation range of FMA minimum power requirements. The shipyard has no choice except to increase the engine power to satisfy FMA minimum power requirement Rule. And the operation cost, efficiency of hullform and its building cost are not good from the ship owners' point of view To solve this problem, the experience of ice breaking tanker development and the ice tank test results were adopted. The main idea to reduce the ice resistance is by reducing waterline angle at design load waterline. The reason behind the main idea is to reduce the ice-clearing force. Two hull forms were developed to satisfy Baltic Ice class IA. Two ice tank tests and one towing tank test was performed at MARC (Kvaener-Masa Arctic Research Center) and SSMB (Samsung Ship Model Basin) facilities, respectively. The purpose of these tests was to verify the performance in ice and open water respectively The hull form 2 shows less speed loss compared to Hull form 1 in open water operation but hull form 2 shows very good ice clearing ability. finally the Hull Form 2 satisfying Baltic ice class IA. The merit of this hull form is to use the same engine capacity and no major design changes in hull form and other related designs But the hull structure has to be changed according to the ice class grade. The difference in two hull form development methods, ice model test methods and analysis methods of ice model test will be described in this paper.

• Membrane and Water Treatment
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• 제6권6호
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• pp.451-476
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• 2015

Membrane distillation (MD), which can utilize low-grade thermal energy, has been extensively studied for desalination. By incorporating solar thermal energy, the solar membrane distillation desalination system (SMDDS) is a potential technology for resolving the energy and water resource problems. Small-scale SMDDS (s-SMDDS) is an attractive and viable option for the production of fresh water for small communities in remote arid areas. The minimum-cost design and operation of s-SMDDS are determined by a systematic method, which involves a pseudo steady state approach for equipment sizing and the dynamic optimization using overall system mathematical models. The s-SMDDS employing three MD configurations, including the air gap (AGMD), direct contact (DCMD) and vacuum (VMD) types, are optimized. The membrane area of each system is $11.5m^2$. The AGMD system operated for 500 kg/day water production rate gives the lowest unit cost of $5.92/m^3$. The performance ratio and recovery ratio are 0.85 and 4.07%, respectively. For the commercial membrane employed in this study, the increase of membrane mass transfer coefficient up to two times is beneficial for cost reduction and the reduction of membrane heat transfer coefficient only affects the cost of the DCMD system.

• Journal of Biosystems Engineering
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• 제36권4호
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• pp.252-256
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• 2011

Consumption of chicken feet has been increasing recently, thus it was necessary to produce good quality of bone less chicken feet. In the process of bone removal during chicken feet production, feeding, conveying, cutting and bone removing process takes about 90% of overall labor. Therefore, the development of a chicken feet-bone remover was necessary to reduce the cost of labor. There has been few research on the chicken feet bone removers so far in Korea as well as worldwide. So the main objective of this study was to develop a chicken feet-bone remover which is suitable for domestic circumstances. The average length of chicken feet was 113.3 mm with maximum and minimum lengths of 135.8 mm and 92.2 mm, and the average diameter of chicken leg was 12.5 mm, average width of the toe was 56.2 mm and the average weight of chicken feet was 26.4 g with maximum and minimum weight of 39.3 g and 16.9 g, respectively. Also, the average moisture content was 64.7% (w.b). The average cutting force of little toes was 15.6 N for the size ranges of less than 3.5 mm, 22.5 N, 3.5~6.0 mm and 30.3 N for larger than 6.0 mm in diameter, respectively.

• 상하수도학회지
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• 제26권4호
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• pp.521-533
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• 2012

Interest in application of ultraviolet light technology for primary disinfection that used for the treatment of water for consumption and wastewater has increased significantly in recent years. Analysis of these systems has been carried out using Computational Fluid Dynamics (CFD) procedure. It offers advantages over other techniques in specific circumstances. CFD has emerged as a powerful tool to aid design of a UV reactor by providing the UV dose delivered by the proposed reactor design and allowing engineers to evaluate alternative designs in much less time and at a reasonable cost. In this study, five different configurations of the apparatus depending on the location of the exit are evaluated in terms of maximum dose, minimum dose, flow patterns, particle tracks and transient dose. The configuration 3 results have higher minimum UV dose value and uniform particle distribution of the UV dose on the outlet than other's.

• Structural Engineering and Mechanics
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• 제76권5호
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• pp.561-578
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• 2020

The present work addresses the surface integrity and chip morphology in finish hard turning of AISI D3 steel under nanofluid assisted minimum quantity lubrication (NFMQL) condition. The surface integrity aspects include microhardness, residual stress, white layer formation, machined surface morphology, and surface roughness. This experimental investigation aims to explore the feasibility of low-cost multilayer (TiCN/Al2O3/TiN) coated carbide tool in hard machining applications and to assess the propitious role of minimum quantity lubrication using graphene nanoparticles enriched eco-friendly radiator coolant based nano-cutting fluid for machinability improvement of hardened steel. Combined approach of central composite design (CCD) - analysis of variance (ANOVA), desirability function analysis, and response surface methodology (RSM) have been subsequently employed for experimental investigation, predictive modelling and optimization of surface roughness. With a motivational philosophy of "Go Green-Think Green-Act Green", the work also deals with economic analysis, and sustainability assessment under environmental-friendly NFMQL condition. Results showed that machining with nanofluid-MQL provided an effective cooling-lubrication strategy, safer and cleaner production, environmental friendliness and assisted to improve sustainability.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제24권2호
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• pp.15-25
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• 2018

Purpose: The important things in space plan of a screening center are improving the spatial awareness by space systemization and minimizing the examination time for customers, and reducing the required time of screening work and maximizing the capacity for the screening center. Therefore, we tried to solve the problem of improving spatial awareness and reducing the examination time by using the pedestrian based discrete event simulation at the minimum cost. Methods: We have analyzed the drawbacks and the supplement points by comparing the floor plan at the time of opening and the current floor plan. Based on the analysis, we propose an improved plan which changes the location of the examination rooms and the number of services, and we also verify the improved plan based on simulation analyses. Results: 1) Through the analyses, we derived the drawbacks of the floor plan at the time of opening, and we realized that the current floor plan reflects the drawbacks. 2) The major reasons of the long examination time are the human traffic jam and the occurrence of queues due to unreasonable allocation of services. 3) Through the discrete event simulation analyses, it was possible to specify the place of the queues manually so as to use the given space fairly. 4) Using the discrete event simulation, it was possible to reduce the examination time and to improve the spatial awareness effectively at the minimum cost. Implications: Although the proposed simulation methodology in this paper is an analysis of the existing screening center, we expect that the proposed methodology will be used to develop a more efficient architectural design process by pre-applying the method to the course of designing a screening center and finding the suitability of the proposed method with the matched number of services.