• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.94-109
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• 1998

The purpose of this study was to evaluate the effect of materials and sizes of files on canal transportation in a curved canal. The stress and the strain energy of files of two kinds of materials (stainless steel and NiTi) and five sizes (No. 20, 25, 30, 35 and 40) in a curved canal were analyzed by a finite element program, NASTRAN. Curved canals in transparent resin blocks were instrumented with the 10 kinds of files, and the degree of canal transportation obtained by double exposure technique of photography was compared with the analysis by the finite element method. The results were as follows : 1. The stress of a file in a curved canal increased from the file body to the file tip. 2. The stress of a stainless steel file was about 2.5 times greater than that of a same-sized NiTi file. 3. The stress distributions of files of an identical material were the same, and the strain energies of files of an identical material increased as the size of files increased. 4. The strain energy of a No. 35 NiTi file was about the same as that of a No. 20 stainless steel file. 5. The degree of canal transportation by a stainless steel file was greater than that by a same-sized NiTi file. The degree of canal transportation generally increased as the size of a file increased. 6. The degree of canal transportation of a No. 35 NiTi file was about the same as that of a No. 20 stainless steel file.

• 한국축산식품학회지
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• 제42권3호
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• pp.486-503
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• 2022

This study explored the physiochemical and rheological properties of chicken breast sausages containing red ginseng marc (RGM) which contains useful components but is discarded. When compared to the control group, the use of RGM significantly increased the water holding capacity (WHC) as the particle size increased. As for the change in color value, addition of RGM resulted in an increase in a and b values; as the quantity was increased and particle size decreased, the a and b values increased significantly. The smaller the particle size of RGM, the greater was the radical scavenging activity. According to the results of the measurement of the viscoelasticity of chicken breast sausage containing RGM, the G' and G'' values increased with increasing amounts of RGM and particle size. Neither the addition of RGM nor its amount or particle size had any significant effect on gel formation temperature. The texture profile analysis (TPA) experiment examined the average TPA measurements of each sample under different measurement conditions, and no significant difference between the RGM and control groups were observed. In conclusion, when RGM is used in chicken breast sausages, the WHC, antioxidant capacity, and viscoelastic properties are affected. RGM can possibly be utilized in high value-added processed meat products if its quantity and particle size are altered based on product characteristics.

• 한국지반신소재학회논문집
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• 제6권4호
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• pp.29-37
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• 2007

시공손상계수는 보강토 옹벽에 사용하는 지오그리드 보강재의 설계 강도 산정에 필요한 중요한 계수로서 실제 조건을 모사한 현장시험을 통해 구하고 있다. 하지만 지오그리드의 시공 중 발생하는 손상은 지오그리드의 재질, 단위면적당 중량, 뒤채움의 시공방법, 뒤채움의 입도에 따라 달라지며 현장시험을 통해 다양한 영향인자를 고려한 시공손상계수값을 도출하는데는 많은 시간과 비용이 소요된다. 본 연구에서는 시공손상에 영향을 미치는 인자들을 분석하고 뒤채움에 포함된 최대입경만을 이용하여 지오그리드 보강재의 시공손상계수를 산정하는 경험적 방법을 제시하였다.

• 전력전자학회논문지
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• 제23권1호
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• pp.1-8
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• 2018

A problem exists in the conventional transportation cart applications, in which an external power supply with mechanical contact connection (bus bar connection) is required to drive the motor. Therefore, continuous effort for maintenance is required, aside from the expensive bus bar connector. To solve this problem, a self-electricity-generated transportation cart system without bus bar has recently been introduced. In this system, a battery needs to store the power of the generated wheel, and a boost converter, which converts the low battery voltage to high bus voltage to drive the motor inverter, is necessary. However, since the instantaneous large current required for starting the motor is supplied from the battery, a battery with large size and volume should be adopted to withstand this large current. In this study, a boost converter that can supply a large instantaneous current by using super Capacitor string is proposed. The proposed converter can be realized with a small size and volume compared with the conventional battery-fed boost converter. Operational principles, analysis, and design of the proposed converter are presented, and experimental results are provided to validate the proposed converter.

• 산업경영시스템학회지
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• 제22권52호
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• pp.117-139
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• 1999

This paper is concerned about the hybrid tandem configuration as the design of the automated guided vehicle system(AGVs). The hybrid tandem configuration is that the manufacturing system is divided into several non-overlapping zones, workstations of each zone are linked by network configuration including loop. That is, the manufacturing system is divided into several non-overlapping small size networks, and at most two automated guided vehicles can be available in each network. The transit point is located at proper point between adjacent networks. The parts are transported to workstations in other network through the transit points. One of the objective functions in dividing into the hybrid tandem configuration is to minimize the maximum travel time of the divided networks, and other is to minimize the total travel distance of parts moved to workstations in other networks for the next processing. The model formulation is presented, and a numerical example is shown. Also, the performances of system for the hybrid tandem, tandem and network configuration are compared through the simulation. The results of this research will contribute to the development of material handling systems in the manufacturing system. Also, it will be applied in determining the transportation area of transportation vehicles and the number and size of the transportation fleet in the transportation problem of logistics management.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.44-51
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• 2019

Designing sophisticate ship structures that satisfy several design criteria simultaneously with minimum weight and cost is an important engineering issue. For a ship structure composed of a shell and stiffeners, this issue is more serious because their mutual effect has to be addressed. In this study, a two-stage optimization method is proposed for the conceptual design of stiffeners in a ship's prow. In the first stage, a topology optimization method is used to determine a potential stiffener distribution based on the optimal results, whereupon stiffeners are constructed according to stiffener generative theory and the material distribution. In the second stage, size optimization is conducted to optimize the plate and stiffener sections simultaneously based on a parametric model. A final analysis model of the ship-prow structure is presented to assess the validity of this method. The analysis results show that the two-stage optimization method is effective for stiffener conceptual design, which provides a reference for designing actual stiffeners for ship hulls.

• Geomechanics and Engineering
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• 제17권4호
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• pp.405-411
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• 2019

A significant influence of the particle size distribution on the resilient behaviour of granular aggregates was usually observed in laboratory tests. However, the mechanisms underlying this phenomenon were rarely reached. In this study, a mechanistic model considering particle breakage is proposed. It is found to be the combined effects of the coefficient of uniformity and the size range between maximum and minimum particle sizes that influences the resilient modulus of granular aggregates. The resilient modulus is found to undergo reduction with evolution of particle breakage by shifting the initial particle size distribution to a broader one.

• 한국도로학회논문집
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• 제12권1호
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• pp.71-78
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• 2010

급격한 도시화는 교통지체를 포함하여 다양한 교통문제를 유발하였다. 따라서 도로건설, 교통소통 위주의 정책을 통해 교통지체 문제를 해결하기 위해 노력하였다. 그러나 차량중심의 교통소통 정책의 한계를 인식하고 최근에는 인간중심의 녹색교통 정책으로 전환 되고 있다. 도로다이어트는 이러한 녹색교통의 하나로 추진되고 있는 개념이다. 도로다이어트는 차로수, 차로폭 등을 줄여서 확보된 공간에 자전거도로, 보행자를 위한 쾌적한 보행로 등 녹색교통을 위한 공간으로 활용하고자 하는 방법이다. 도로다이어트는 최근에 도이된 개념으로 아직 구체적이고 실증적인 연구가 많이 수행되지 못하고 있는 실정이다. 따라서 본 연구에서는 도로다이어트를 위한 차로폭 축소 방안에 대한 기초적이고 실증적인 연구를 수행하였다. 현장조사를 통해 차로를 주행하는 차량의 차로중심선에서 이격량을 분석하여 차량이 주행시에 필요로 하는 최소한의 차로폭을 분석하였다. 분석결과 소형차의 경우 조사지점별로 2.34~2.70m, 대형차의 경우에는 2.62~2.89m의 차로폭이 필요한 것으로 나타나 도로다이어트 등 설계자의 목적에 따라 차로폭을 다소 축소할 수 있도록 설계기준을 완벽할 필요가 있을 것으로 판단된다. 본 연구결과는 도로다이어트, 도로공사 등으로 인해 동행이 가능한 도록폭이 축소되었을 때 차로폭 축소를 위한 설계기준으로 활용될 수 있을 것이다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.159-166
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• 2006

The aim of synchronization of production and transportation planning in the supply chain is to increase the flexibility and to decrease various costs. The suggested model in this study synchronizes the timing to supply to a downstream manufacturer directly after production and to be consumed in a downstream manufacturer right after receipt. This model deals with the frequent delivery in small amount which is a new trend of the transportation not governed the economy of scale principle. Moreover, various types of transportation governed by the economy of scale principle or not are considered. Then, the two-phase mathematical model is suggested to obtain optimal job sequence and production quantity for each tasks. But, it is difficult to gain optimal solutions if there is a transportation governed by the economy of scale principle in the supply chain, or the size of the problem is increased. Thus, heuristic algorithms based on simulated annealing and genetic algorithm are suggested to find good solutions in the reasonable time.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.95-98
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• 1998

Applying the magnetically levitated transportation system, which is noncontact bearing system, to solve the problems such as transformation of original form or flaw of iron plate caused by transportation of thin iron plate which required high quality as body of motor vehicle, materials of electronic devices etc.. Magnetic saturation phenomena caused by thickness of iron plate and gap size between magnets. In case of iron plate, the vibration mode will be considered since vibration occurs during transportation. In order to solve the problems caused by vibration, choose the levitation system method using numbers of magnet, magnetic saturation for thickness and length of iron plate with parameters in location and gap of magnet. In this paper, we will suggest the whole design technique of magnetically levitated transportation system, namely method of magnetic attraction and transportation system