• 소성∙가공
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• 제31권3호
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• pp.143-150
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• 2022

The purpose of this study was to investigate an innovative hydroforming process for the cost-effective manufacturing of double layered tube with circumferentially corrugated patterns. Conventional double pipe heat exchanger has relatively poor heat transfer efficiency because of the limited contact area resulting from the concentrically arranged simple cylindrical structure. As a promising alternative to enhance heat transfer efficiency, double layered tube with corrugated internal pattern was considered in this study. To fabricate corrugated inner tube, innovative tube hydroforming system was developed. The customized loading paths were established using the simulated forming pressure and contracting stroke at various bar diameters. Experimentally obtained cross-sectional profiles were analyzed to evaluate the reliability and applicability of the hydroformed tube with various patterns. The results demonstrate that the proposed hydroforming process can be a feasible alternative for manufacturing high-performance double-tube heat exchangers.

• 경영과학
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• 제26권1호
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• pp.93-112
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• 2009

In this paper, a model is presented to estimate a cycle time for completing an operation in a new type of AS/RS which can handle very heavy loads by separating the mechnisms for vertical and horizontal movements. Considering loading/unloading time between devices, we generalize the previous work, Hu et al. [9], which neglected the transfer time. Through the numerical experiments for various situations, we find that the difference of the cycle times between two models is fairly large and conclude that the transfer time between devices cannot be neglected at all.

• 한국해양공학회지
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• 제2권2호
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• pp.130-137
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• 1988

This thesis introduced that character of a treatment technique for a mading synthetic resin Hifiow-Ring. The material system of packings make an experiment air$NH_{3}$/air$H_{2}SO_{4}$, $SO_{2}$-air/NaOH, $NH_{3}$-air/$/H_{2}SO_{4}$ under general conditions. Lattices packing compared with conventional packings was proved low pressure loss and high separation efficiency for high loading per trans unit. And an inflow materal tested for absorption and rectification, it made an experiment under a range regular temperature, low energy and small amount of money. That made possible in simple equation, volume material tranfer coefficient$\beta_{L}$ . a by absorption or $\beta_{V}$ .a calculated in all range loading. The peculiarity pressure loss $\Delta\;P/NUT_{ov}$ for Hiflow-ring contributed to a fall cost of energy, a grade number of a vacuum rectification and absorption calculation.

• 한국강구조학회 논문집
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• 제21권2호
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• pp.145-154
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• 2009

이 논문에서는 새롭게 제안된 접합부를 적용한 단층 래티스 돔의 비탄성 거동에 대해 실험적으로 분석하였다. 구조적인 성능과 시공성을 모두 만족시키기 위해서 제안된 새로운 접합부를 적용하여 강관으로 구성된 스팬 7m의 단층 래티스 돔의 축소실험모델을 제작하였으며, 각 절점에 균일한 하중이 가력되도록 하중전이장치를 이용하여 정적재하실험을 수행하였다. 최대가력하중은 1,114kN이었고, 일부 접합부의 항복 이후에 강관부재의 좌굴이 발생하였다. 강관부재의 좌굴발생 이후에는 가력장치가 허용할 수 있는 변위까지 실험을 수행하였으며, 실험을 통해서 구해진 단층 래티스 돔의 비탄성거동을 하중 단계별로 분석하였다.

• 한국산학기술학회논문지
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• 제20권11호
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• pp.494-500
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• 2019

본 연구는 탄약운반장갑차의 장약이송 소프트웨어 최적 설계를 통해 장약이송 시 파손을 방지하는 것을 목표로 하고 있다. 탄약운반장갑차는 자동화된 장약이송시스템이 적용되어 있다. 군 운용 중 장약 적재 시 간헐적으로 장약이 파손되는 현상이 발생하여 다음과 같은 개선방법을 연구하였고, 입증시험을 실시하였다. 장약 이송기의 속도가 높을 경우 충격력이 증가하기 때문에 적재 속도를 기존보다 60% 감소 시켰고, 포스 게이지를 활용하여 충격력을 측정하였다. 충격력 측정 결과 평균 45% 감소하는 것을 확인 할 수 있었다. 적재관 내부의 간섭 등에 의한 이송기의 부하 발생 시 서보제어기의 최대전류 11A를 출력하면 장약이 파손 될 가능성이 있다. 또한, 최대전류가 낮을 경우 장약적재가 불가하기 때문에 적정 값을 찾아야 했고, 이는 시험을 통하여 최적의 최대전류 값 6.5A를 도출하였다. 최적설계 입증 시험에는 종이지관장약과 실제장약을 적용하여 시험 하였다. 종이지관 장약과 실제 장약으로 탄운차에 장약 적재시험을 실시한 결과 장약의 파손이 발생하지 않았으며, 장약 적재가 정상적으로 이루어져 설계 개선이 타당한 것을 입증하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.392-395
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• 2003

In the maritime container terminal, LMTT (Linear Motor-based Transfer Technology) is horizontal transfer system for the yard automation, which has been proposed to take the place of AGV (Automated Guided Vehicle). The system is based on PMLSM (Permanent Magnetic Linear Synchronous Motor) that is consists of stator modules on the rail and shuttle car (mover). Because of large variant of mover's weight by loading and unloading containers, the difference of each characteristic of stator modules, and a stator module's trouble etc., LMCPS (Linear Motor Conveyance Positioning System) is considered as that the system is changed its model suddenly and variously. In this paper, we will introduce the soft-computing method of a multi-step prediction control for LMCPS using DR-FNN (Dynamically-constructed Recurrent Fuzzy Neural Network). The proposed control system is used two networks for multi-step prediction. Consequently, the system has an ability to adapt for external disturbance, cogging force, force ripple, and sudden changes of itself.

• 한국자기학회지
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• 제22권3호
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• pp.97-102
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• 2012

본 논문은 전선을 통하여 전력을 전달하는 일반적인 전력전송방식이 사용될 수 없는 환경에서 무선으로 전력을 전송하는 비접촉 전력전송기기 개발에 관한 것이다. 전력전송 방식은 자기공명방식보다 큰 전력을 전송하기에 적합한 전자기유도방식을 이용 하였다. 전력전송기기의 설계 방법은 전기장하(Electirc loading)와 자기장하(Magnetic loading)의 비율로 코어와 코일을 설계하는 장하분배법(Loading Distribution Method)으로 설계 하였고 유한요소법(Finite Elements Method)으로 기기에 발생하는 전자기장을 해석하여 설계한 전력전송기기의 적합성을 판단하고 적정한 설계치를 보정하였다. 본 연구를 통하여 개발된 전력전송방식은 비접촉식으로 수 mm 거리를 가지는 근거리에서 무선으로 전력을 전송하기에 적합함을 보였다.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1556-1565
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• 2017

This paper depicts the design, implementation and analysis of efficient resonant based wireless power transfer (WPT) technique using three magnetic coupled coils. This work is suitable for mid ranged device due to small form factor while minimizing the loading effect. A multi turned loop size resonator is exploited for both the transmitter and receiver for longer distance. In this paper, class-E power amplifier (class-E PA) is introduced with an optimum power tracking mechanism of WPT system to enhance the power capability at mid-range with a flat gain. A robust method of finding optimum distance is derived with an experimental analysis of the designed system. In this method, the load sensitive issue of WPT is resolved by tuning coupling coefficient at considerable distances. Our designed PA with a drain efficiency of 77.8% for a maximum output of 5W is used with adopted tuning technique that improves the overall WPT system performance by 3 dB at various operating points.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.980-985
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• 2002

Several tests are performed to evaluate road booming noise. Baseline test delivers the information of road noise characteristics. Coupling effect between structure and acoustics is obtained from the mode shapes and the natural frequencies by the modal test. Equivalent stiffness at joint areas between chassis and car-body system can be determined by the input point inertance test. Noise sensitivity of body mounting point of a chassis part can be obtained from the noise transfer function test with input point inertance test. Operational deflection shape makes us analyze the actual vibration modes of the chassis system under actual loading and find noise sources very easily. finally, the transfer function analysis is used to identify noise paths through the chassis system. However, all of the tests above mentioned must be performed to evaluate road booming noise. The objectives and the procedures of the tests are described in this paper. Also, the guideline for efficient road noise evaluation test can be found.

• 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.