• 대한산업공학회지
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• 제21권2호
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• pp.153-165
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• 1995

Many closed queueing network models have been used as an effective tool to make a preliminary design of FMS. Although a loading/unloading function is an important factor to effect the utilization and throughput of FMS as well as a transfer function and a processing function, the Solberg's model did not clarify the loading/unloading function. In this paper, we propose a closed queueing network model for analyzing a flexible manufacturing system that consists of a load/unload station, a material handling system and a group of workstations for processing jobs, and define the expected utilization and the expected throughput of the FMS. As applications of the proposed model, the cases of a material handling system consisting of a conveyor and the FMS including an inspection station are also formulated.

• Journal of Welding and Joining
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• 제6권4호
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• pp.35-43
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• 1988

Welding residual stresses were calculated by two dimensional thermal elasto-plastic analysis using element method. Complicated plastic behavior during heat transfer was simulated with time. Fist, temperature distributions. To consider time varying behavior of material properties and loading and unloading processes, iterative calculation based on initial stiffness method was carried out. The method proposed by Yamata was used in time increment control which determined the accuracy of claculation. comparison with other caculated and experimental results shows fairly good agreement.

• 경영과학
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• 제27권2호
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• pp.45-54
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• 2010

In this paper we analyze the effects of loading-unloading environments on the efficiency of freight railroad stations using a two-stage procedure for efficiency model estimation. And from the results we explore a way for efficiency improvement of freight railroad stations. Two-stage procedure is composed of data envelopment analysis and regression analysis. The results show that we could expect efficiency improvement through the government"s effort to make railway stations to be strategic position. Furthermore, they advocate policy-makers that efficiency can be improved by simplifying the kinds of freight items and increasing the scale.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.519-524
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• 2003

In this paper we discuss the dynamic characteristics of the in-arm type hydropneumatic suspension unit(ISU). For this, two accurate models are introduced. The first one is the Benedict-Webb-Rubin equation which is adopted for the spring behavior of a real gas. This equation is applicable for the high pressure of the nitrogen gas which acts as a spring in ISU system. The second one describes the behavior of a damper, which is divided into four parts - jounce-loading, jounce-unloading, rebound-loading and rebound-unloading. This approach gives a good approximation of the real damper system. For the comparison purpose, the numerical results of the dynamic behavior of ISU system using a real gas and an ideal gas are given in the paper.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.61-64
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• 2009

Recently, the higher buildings are, the stronger concrete are used. Ultra high strength concrete have the possibility of spalling when a fire breaks out. so the fire-resistance performance is necessary to use the ultra high strength concrete on the high-rise building. On this study, the heating test for the concrete with loading/unloading is performed for ultra high strength concrete using nylon fiber. The heating test followed by ISO-834 heating curve on the real-size specimen and the strength of concrete are 60, 80, 100, 200 MPa.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1092-1098
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• 2004

Today the demand of the optical communication components has been increased. Zirconia Ferrule has become the one of the most important elements because it determines transmission efficiency and quality of information in the optical communication system. Grinding is the major process in the ferrule manufacturing process which require high processing precision. In this reseach, specially designed spindle, chucking system, loading & unloading system and cooling system, as a supporting experimental equipment for development of an Intelligent Coaxial Grinding System (ICGS) for Zirconia Ferrule processing, is developed. We are also analized the adaptability of ICGS in practical use, through the way of evaluation for the performance of the each systems above.

• Journal of Biosystems Engineering
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• 제13권3호
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• pp.44-51
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• 1988

The objective of this study is to develop a grain handling system for loading, unloading and transporting of rough rice stored at the in-bin drying and storage (IBDS) developed by the Korea Advanced Institute of Science and Technology(KAIST). A mechanized Fain handling system consisted of a portable auger and a gate was developed and tested. The test results can be summarized as the following: 1) The loading capacity of the handling system developed is $16.2m^3/h$ (8.3 ton/h) for the Indica type rice and $13.0m^3/h$(7.3 ton/h) for the Japonica type. It is greater than that of manual handling as much as 2.5 - 2.7 times. 2) The unloading capacity of the handling system developed is $16.0m^3/h$(8.2 ton/h) for the Indica type rice and $12.6m^3/h$(7.0 ton/h) for the Japonica type. It is greater than that of the manual as much as 4.7 - 5.5 times. 3) For 3-ton capacity of the storage, the loading and unloading can be performed for 20 and 30 minutes by one man operation of equipment. while 60 and 120 minute for the manual of 2 men, respectively. 4) The volumetric efficiency of the system developed is 0.42 - 0.54 and the power efficiency is 4.0 - 4.4. 5) The break-even quantity of the handling system developed is about 38.6 ton($68.7m^3$) of rough rice and the initial investment for the system would be returned within five years for the most owners of the KAIST IBDS system.

• 한국정보통신학회논문지
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• 제11권10호
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• pp.1999-2007
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• 2007

본 논문은 야드에서 스태커의 위치 정보를 이용한 효율적인 선적 하역 작업을 수행하기 위한 개선된 클로버 알고리즘에 대하여 기술하고 있다. 작업 스케쥴링은 반드시 스태커의 작업 할당과 스태커의 위치정보를 능동적으로 처리하기 위한 위치 데이터 처리에 중점을 두어야 하며 작업요구에 따른 복수의 스태커들의 작업 할당관리를 수행할 수 있어야 한다. GPS와 GIS를 이용한 스태커의 위치 추적은 야드 관리에 필수 요소이며 선적 하역 작업의 개선에도 필요한 요소 기술이다. 본 논문에서 제안하는 개선된 클로버 알고리즘은 야드 내에서의 스태커들의 위치를 추정하고 각 컨테이너들의 선적하역 작업을 모니터링하는 기법과 스태커의 작업량을 추정함으로써 다수의 스태커들의 작업 균형을 이루기 위한 기법을 소개하고 있다. 시뮬레이션 결과와 실험 결과로부터 제안한 알고리즘이 효율적임을 나타내고 있다.

• Geomechanics and Engineering
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• 제14권3호
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• pp.225-231
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• 2018

In this paper, in order to explain the splitting of cylindrical rock specimen under uniaxial loading, cracks in cylindrical rock specimen are divided into two kinds, the longitudinal crack and the slanting crack. Mechanical behavior of the rock is described by elastic-brittle-plastic model and splitting is assumed to suddenly occur when the uniaxial compressive strength is reached. Expression of the stresses induced by the longitudinal crack in direction perpendicular to the major axis of the crack is deduced by using the Maxwell model. Results show that the induced stress is tensile and can be greater than the tensile strength even before the uniaxial compressive strength is reached. By using the Inglis's formula and simplifying the cracks as slender ellipse, the above conclusions that drawn by using the Maxwell model are confirmed. Compared to shearing fracture, energy consumption of splitting seems to be less, and splitting is most likely to occur when the uniaxial loading is great and quick. Besides, explaining the rock core disking occurred under the fast axial unloading by using the Maxwell model may be helpful for understanding that rock core disking is fundamentally a tensile failure phenomenon.

• Structural Engineering and Mechanics
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• 제77권2호
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• pp.261-272
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• 2021

The energy-saving block and invisible multi-ribbed frame composite wall (EBIMFCW) is a new type of load-bearing wall. The study of this paper focus on it is hysteresis rule under horizontal cyclic loading. Firstly, based on the experimental data of the twelve specimens under horizontal cyclic loading, the influence of two important parameters of axial compression ratio and shear-span ratio on the restoring force model was analyzed. Secondly, a tetra-linear restoring force model considering four feature points and the degradation law of unloading stiffness was established by combining theoretical analysis and regression analysis of experimental data, and the theoretical formula of the peak load of the EBIMFCW was derived. Finally, the hysteretic path of the restoring force model was determined by analyzing the hysteresis characteristics of the typical hysteresis loop. The results show that the curves calculated by the tetra-linear restoring force model in this paper agree well with the experimental curves, especially the calculated values of the peak load of the wall are very close to the experimental values, which can provide a reference for the elastic-plastic analysis of the EBIMFCW.