• 산업공학
• /
• 제13권2호
• /
• pp.217-224
• /
• 2000

This paper analyzes the effects of setup cost reduction in a dynamic lot-sizing model for a single-facility multi-product problem. In the model, demands for each product are known, no backlogging is allowed, and a single resource is employed. Also, setup cost is defined as a function of capital expenditure to invest in setup cost reduction. Furthermore, in each production period the facility (or plant) produces many products, each representing a fixed part of the involved production activity (or input resource quantity). In this paper, the structure of the optimal solution is characterized and an efficient algorithm is proposed for simultaneously determining the optimal lot size with reduced setup cost and the optimal investment in setup cost reduction. Also, the proposed algorithm is illustrated by a numerical example with a linear and an exponential setup reduction functions.

• 한국기계가공학회지
• /
• 제15권1호
• /
• pp.34-41
• /
• 2016

Bar camber is a phenomenon in which a material with a deformation gradient across its width is bent in the right or left direction in the roll gap. This paper proposes a dynamic setup approach for a side guide for reducing bar camber. A bar tracking scheme using a rotary encoder was adopted to fix an operation point for the side guide. The guiding pressure was utilized for measuring the actual width of the bar with camber. Based on the accurate position and width of the bar, the side guide was dynamically set and operated at the actual roughing train in a hot strip rolling mill. The amount of camber was reduced notably when the dynamic setup scheme was installed in the side guide. 78% of the bars tested had a camber in the range of ${\pm}20mm$, which was an improvement of 27% in terms of production yield.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2004년도 ICCAS
• /
• pp.956-959
• /
• 2004

Recently the monitoring system of tool setting in high speed precision machining center is required for manufacturing products that have highly complex and small shape, high precision and high function. It is very important to reduce time to setup tool in order to improve the machining precision and the productivity and to protect the breakage of cutting tool as the shape of product is smaller and more complex. Generally, the combination of errors that geometrical clamping error of fixing tool at the spindle of machining tool and the asynchronized error of driving mechanism causes that the run-out of tool reaches to 3$^{\sim}$20 times of the thickness of cutting chip. And also the run-out is occurred by the misalignment between axis of tool shank and axis of spindle and spindle bearing in high speed rotation. Generally, high speed machining is considered when the rotating speed is more than 8,000 rpm. At that time, the life time of tool is reduced to about 50% and the roughness of machining surface is worse as the run-out is increased to 10 micron. The life time of tool could be increased by making monitoring of tool-setup easy, quick and precise in high speed machining tool. This means the consumption of tool is much more reduced. And also it reduces the manufacturing cost and increases the productivity by reducing the tool-setup time of operator. In this study, in order to establish the concept of tool-setup monitoring the measuring method of the geometrical error of tool system is studied when the spindle is stopped. And also the measuring method of run-out, dynamic error of tool system, is studied when the spindle is rotated in 8,000${\sim}$60,000 rpm. The dynamic phenomena of tool-setup are analyzed by implementing the monitoring system of rotating tool system and the non-contact measuring system of micro displacement in high speed.

• 한국경영과학회지
• /
• 제26권2호
• /
• pp.69-83
• /
• 2001

The problem of minimizing total tardiness on a batch processing machine with incompatible job families when there are sequence independent setup times between families is studied where all jobs of the same family have identical processing times and jobs of different families cannot be processed together. A batch processing machine can process a number of jobs, within a maximal batch size, simultaneously as a batch. The processing time required of each batch is equal to the one of jobs. A dynamic programming algorithm which gives the optimal solution, and several heuristics are presented. Performance of simple dispatching rules based on due dates are compared, and the best of them is used as an initial solution for the decomposition algorithm, which is shown to give good schedules in relatively short computational time.

• Geomechanics and Engineering
• /
• 제4권4호
• /
• pp.251-262
• /
• 2012

Triaxial tests are essential to estimate the shear strength properties of the soil or rock. Normally triaxial tests are carried out on samples of 38 mm diameter and 76 mm height. Granular materials, predominantly used in base/sub-base construction of pavements or in railways have size range of 60-75 mm. Determination of shear strength parameters of those materials can be made possible only through triaxial tests on large diameter samples. This paper describes a large diameter cyclic triaxial testing facility set up in the Geotechnical Engineering lab of Indian Institute of Science. This setup consists of 100 kN capacity dynamic loading frame, which facilitates testing of samples of up to 300 mm diameter and 600 mm height. The loading ram can be actuated up to a maximum frequency of 10 Hz, with maximum amplitude of 100 mm. The setup is capable of carrying out static as well as dynamic triaxial tests under isotropic, anisotropic conditions with a maximum confining pressure of 1 MPa. Working with this setup is a difficult task because of the size of the sample. In this paper, a detailed discussion on the various problems encountered during the initial testing using the equipment, the ideas and solutions adopted to solve them are presented. Pilot experiments on granular sub-base material of 53 mm down size are also presented.

• 대한전자공학회논문지TC
• /
• 제41권12호
• /
• pp.9-14
• /
• 2004

최근 인터넷 트래픽의 종류 및 크기의 다양화로 인해 광 네트워크의 동적인 경로 설정을 위한 GMPLS(Generalized Multi-Protocol Label Switching) 기반의 트래픽 제어 및 관리 프로토콜이 지속적으로 제안되고 있다. 이에 본 논문에서는 광역정보를 이용한 프로토콜과 지역정보를 이용한 프로토콜을 기반으로 한 네트워크 성능평가를 통해 두 가지 프로토콜의 특성을 비교 분석하였다. 네트워크 성능평가를 위해 변화 정보에 대한 업데이트 주기 및 임계값을 평가 메트릭으로 사용하여 트래픽 발생 율에 따른 연결 설정 시간, 제어신호 요구 대역폭, 경로 설정 블록킹 확률을 산출하였다. 평가된 프로토콜은 미래의 IP네트워크를 위한 광대역 네트워크의 필요조건이며 이는 고속의 백본 네트워크를 만족시키는 솔루션이 될 것으로 사료된다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2004년도 추계학술대회 논문집
• /
• pp.1066-1069
• /
• 2004

Recently the monitoring system of tool setup in high speed precision machining tool is required for manufacturing products that have highly complex and small shape, high precision and high function. It is very important to reduce time to setup tool in order to improve the machining precision and productivity and to protect the breakage of cutting tool as the shape of product is smaller and more complex. Generally, the combination of errors that geometrical clamping error of fixing tool at the spindle of machining center and the asynchronized error of driving mechanism causes that the run-out of tool reaches to 3∼20 times of the thickness of cutting chip. And also the run-out is occurred by the misalignment between axis of tool shank and axis of spindle and spindle bearing in high speed rotation. Generally, high speed machining is considered when the rotating speed is more than 8,000 rpm. At that time, the life time of tool is reduced to about 50％ and the roughness of machining surface is worse as the run-out is increased to 10 micron. The life time of tool could be increased by making monitoring of tool-setting easy, quick and precise in high speed machining center. This means the consumption of tool is much more reduced. And also it reduces the manufacturing cost and increases the productivity by reducing the tool-setup time of operator. In this study, in order to establish the concept of tool-setting monitoring the measuring method of the geometrical error of tool system is studied when the spindle is stopped. And also the measuring method of run-out, dynamic error of tool system, is studied when the spindle is rotated in 8,000 ∼ 60,000 rpm. The dynamic phenomena of tool-setup is analyzed by implementing the monitoring system of rotating tool system and the noncontact measuring system of micro displacement in high speed.

• Computers and Concrete
• /
• 제28권5호
• /
• pp.479-486
• /
• 2021

Reinforced concrete (RC) slabs are exposed to several static and dynamic effects during their period of service. Accordingly, there are many studies focused on the behavior of RC slabs under these effects in the literature. However, impact loading which can be more effective than other loads is not considered in the design phase of RC slabs. This study aims to investigate the dynamic behavior of two-way RC slabs under sudden impact loading. For this purpose, 3 different simply supported slab specimens are manufactured. These specimens are tested under impact loading by using the drop test setup and necessary measurement devices such as accelerometers, dynamic load cell, LVDT and data-logger. Mass and drop height of the hammer are taken constant during experimental study. It is seen that rigidity of the specimens effect experimental results. While acceleration values increase, displacement values decrease as the sizes of the specimens have bigger values. In the numerical part of the study, artificial neural networks (ANN) analysis is utilized. ANN analysis is used to model different physical dynamic processes depending upon the experimental variables. Maximum acceleration and displacement values are predicted by ANN analysis. Experimental and numerical values are compared and it is found out that proposed ANN model has yielded consistent results in the estimation of experimental values of the test specimens.

• 대한방사선치료학회지
• /
• 제31권2호
• /
• pp.13-24
• /
• 2019

목 적: 두경부 토모테라피 치료 시 다양한 이유로 CT scan range가 부족한 상황이 발생한다. CT scan range는 정확한 선량 계산에 영향을 주기 때문에 Re-CT Simulation이 좋지만 환자의 피폭선량 증가와 불편함, 치료일정 변경 등 문제점을 갖는다. 이에 본 저자는 기존 CT scan range에서 Plan setup parameter 변화를 통해 Re-CT Simulation 없이 정확한 치료계획에 필요한 최소한의 CT scan range를 평가해보고자 한다. 대상 및 방법: CT simulator(Discovery CT590 RT, GE, USA)와 In House Head & Neck Phantom을 이용하였고, Target의 끝단에서 0.25~3.0cm까지 0.25cm씩 증가시켜 CT scan range 별 이미지를 획득하였다. Target과 정상 장기를 Head & Neck Phantom에 등록하고 ACCURAY Precision^® 이용하여 치료계획을 설계하였다. 처방 선량은 Daily 2.2Gy, 27 Fxs, Total Dose 59.4Gy, Target은 처방 선량의 95~107%, 정상 장기는 SMC Protocol에 맞춰 치료계획을 설계하였다. 동일한 치료계획 조건에서 Field Width(FW)와 Jaw 모드를 고려한 5가지 방법(Fixed-1cm, Fixed-2.5cm, Fixed-5cm, Dynamic-2.5cm Dynamic-5cm)과 2가지 Pitch(0.43, 0.287)의 Plan Setup parameter로 치료계획을 설계하였다. 각 치료계획에 대한 선량 전달의 정확성은 EBT3 film과 RIT(Complete Version 6.7, RIT, USA)를 이용하여 분석하였다. 결 과: Target의 처방 선량과 정상 장기의 견딤선량(Tolerance dose)을 만족한 치료계획(SMC Protocol)은 Fixed-1cm은 0.25cm 이상, Fixed-2.5cm는 0.75cm 이상, Dynamic-2.5cm는 1cm 이상, Fixed-5cm과 Dynamic-5cm인 경우는 1.75cm 이상의 Scan range가 있어야 정확한 치료계획을 할 수 있었다. 선량 전달의 정확성은 RIT로 분석한 결과 SMC Protocol을 만족한 치료계획에서 3% 미만의 오차였다. 결 론: 두경부 토모테라피 치료 시 CT scan range가 부족한 경우 Plan Setup Parameter 중 Field Width(FW)를 조절하여 정확한 치료계획을 설계할 수 있었다. 이에 본 저자가 추천한 Plan Setup Parameter를 CT scan range에 따라 적용하고 Re-CT 여부를 판단한다면 업무의 효율성 및 환자의 피폭선량을 감소시킬 수 있을 것으로 사료된다.

• 대한산업공학회지
• /
• 제31권3호
• /
• pp.194-200
• /
• 2005

A stochastic dynamic lot sizing problem for multi-item is suggested in the case that the distribution of the cumulative demand is known over finite planning horizons and all unsatisfied demand is fully backlogged. Each item is produced simultaneously at a variable ratio of input resources employed whenever setup is incurred. A dynamic programming algorithm is proposed to find the optimal production policy, which resembles the Wagner-Whitin algorithm for the deterministic case problem but with some additional feasibility constraints.