• 소성∙가공
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• 제8권1호
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• pp.47-56
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• 1999

The governing functional in plastic deformation has to satisfy the incompressibility constraint. This incompressibility constraint imposed on velocity fields can be removed by introducing either Lagrange multiplier or the penalty constant into the functional. In this study, two-dimensional rigid plastic FEM programs using these schemes were developed. These two programs and DEFORM were applied in a cylinder upsetting and a closed die forging to compare the values of load, local mean stress and volume loss. As the results, the program using Lagrange multiplier obtained a more exact and stable solution, but it took more computational time than the program using the penalty constant. Therefore, according to user's need, one of these two programs can be chosen to simulate a metal forming processes.

• 한국콘텐츠학회논문지
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• 제5권1호
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• pp.169-178
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• 2005

본 논문에서는 인터넷에서의 트래픽 엔지니어링 체제를 구축하기 위하여 트래픽 엔지니어링을 수행하기 위한 상위레벨 기능 모델을 제시하였다. 제시한 기능 모델은 트래픽 관리, 용량 관리, 그리고 네트워크 계획으로 구성된다. 트래픽 관리는 다양한 조건하에서 네트워크 성능을 최대화하는 것을 목적으로 하며, 용량 관리는 최소의 비용으로 네트워크 요구에 대한 성능 목표치를 만족시키기 위하여 네트워크가 설계되고 제공됨을 목적으로 한다. 또한 네트워크 계획은 예측된 트래픽 증가에 앞서 노드와 전송 용량이 계획되고 배치됨을 보장한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.257-260
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• 1999

We have designed a 32-bit RISC microprocessor with 16/32-bit fixed-point DSP functionality. This processor, called YRD-5, combines both general-purpose microprocessor and digital signal processor (DSP) functionality using the reduced instruction set computer (RISC) design principles. It has functional units for arithmetic operation, digital signal processing (DSP) and memory access. They operate in parallel in order to remove stall cycles after DSP and load/store instructions with one or more issue latency cycles. High performance was achieved with these parallel functional units while adopting a sophisticated 5-stage pipeline structure and an improved DSP unit.

• Journal of Power Electronics
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• 제15권6호
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• pp.1547-1558
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• 2015

A predictive functional control (PFC) scheme for permanent magnet synchronous motor (PMSM) servo systems is proposed in this paper. The PFC-based method is first introduced in the control design of speed loop. Since the accuracy of the PFC model is influenced by external disturbances and speed detection quantization errors of the low distinguishability optical encoder in servo systems, it is noted that the standard PFC method does not achieve satisfactory results in the presence of strong disturbances. This paper adopted the Kalman filter to observe the load torque, the rotor position and the rotor angular velocity under the condition of a limited precision encoder. The observations are then fed back into PFC model to rebuild it when considering the influence of perturbation. Therefore, an improved PFC method, called the PFC+Kalman filter method, is presented, and a high performance PMSM servo system was achieved. The validity of the proposed controller was tested via experiments. Excellent results were obtained with respect to the speed trajectory tracking, stability, and disturbance rejection.

• Journal of Communications and Networks
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• 제18권2호
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• pp.162-172
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• 2016

The placement of the complete baseband processing in a centralized pool results in high data rate requirement and inflexibility of the fronthaul network, which challenges the energy and cost effectiveness of the cloud radio access network (C-RAN). Recently, redesign of the C-RAN through functional split in the baseband processing chain has been proposed to overcome these challenges. This paper evaluates, by mathematical and simulation methods, different splits with respect to network level energy and cost efficiency having in the mind the expected quality of service. The proposed mathematical model quantifies the multiplexing gains and the trade-offs between centralization and decentralization concerning the cost of the pool, fronthaul network capacity and resource utilization. The event-based simulation captures the influence of the traffic load dynamics and traffic type variation on designing an efficient fronthaul network. Based on the obtained results, we derive a principle for fronthaul dimensioning based on the traffic profile. This principle allows for efficient radio access network with respect to multiplexing gains while achieving the expected users' quality of service.

• 산업경영시스템학회지
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• 제19권40호
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• pp.107-117
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• 1996

This paper considers the part assignment to workstations in flexible manufactuirng system (FMS). Parts are processed through several workstations according to processing order. The machines of each workstation can do multiple Processing functions. Therefore, a processing of a part can be processed in several workstations, which are non-identical in functional performance. Although a processing of a part can be processed in the multiple workstations, it has to be processed in only one among available several workstations, Parts are transported with unit load by automated guided vehicles (AGVs). The criteria of part assignment is to minimize the maximum value of the processing times of each workstation and the total transport times of vehicles. Model formulation is suggested, and numerical example is shown.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.11-14
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• 2007

CMOS technology 기반의 고주파 직접회로에서는 충분한 이득과 안정성을 얻기 위하여 inductor, capacitor와 같은 수동 소자를 적절히 사용하여 설계하여야 한다. 이와 같은 수동 소자는 CMOS 집적회로에서 넓은 면적을 차지하는 단점이 있다. 고주파 증폭기의 부하를 능동 소자로 대체하게 되면 작은 크기로 회로의 제작이 가능하게 되나, 능동 소자는 수동 소자에 비하여 선형 특성이 좋지 않기 때문에 실제로 고주파 증폭기 설계에 사용하지 않는다. 본 논문에서는 이와 같은 능동 소자의 비선형성을 억제하면서, 동시에 회로의 크기를 줄일 수 있는 기능성 능동 부하를 적용한 고주파 증폭기를 설계하였다. 기능성 능동 부하는 2개의 MOSFET은 대칭으로 연결된 구조를 가지며, 하나의 MOSFET은 일반적인 load로 동작하며, 다른 MOSFET은 gate에 가변 전압을 인가함으로써, 증폭기의 전달함수를 변화시킬 수 있다. 이와 같은 특성을 이용하여 고주파 증폭기의 선형성을 보상할 수가 있다.

• 산업경영시스템학회지
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• 제15권26호
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• pp.125-136
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• 1992

Primary prevention of low back injury in industry has focused on assessing the person's ability to perform physical labor. If the job to be performed is known to require lifting and moving of materials which could stress the low back, then special consideration is given to the health and functional capability of the person, s back. The major pursuit in lifting task of research is to provide objective criteria based upon all of the relevant mechanical parameters which describe both man art task so as to minimize the probabilities of injury within the economic constraints of each organization. The purpose of this study is to predict the back compression of persons asked to lift objects while assuming different position by computer simulation. The primary result of this study is that the incidence of low back injury is correlated with higher lifting strenth requirements as determined by assessment of both the location and magnitude of the load lifted. It is, therefore, recommended that load lifting be considered potentially hazardous, and the action limit and the maximum permissiable limit be used to guide corrective action.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.515-516
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• 2006

The goal of total disc replacement is to restore pain-free mobility to a diseased functional spinal unit, by replacing the degenerated disc with a mobile bearing prosthesis. SB Charite III is named commercial product as the Artificial Intervertebral Disc (AID). SB Charite III consists of sliding core and endplate made by Ultra-high Molecular Weight Polyethylene (UHMWPE) and cobalt chrome alloy, respectively. To evaluate the effect of von-Mises stress in AID, and three-dimensional finite element model of AID analysis was preformed for four different loading types of sliding core. Consequently, endplate was compared with a compressive preload at 400N and flexion moment at $3{\sim}9Nm4. Therefore, this research has obtained result that von-Mises stress of sliding core in AID disc by radius curvature.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.2054-2056
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• 1998

A conventional UPS can supply the clean power to the load. However, it may generate input current harmonics and the input power factor can be very poor. Therefore, the UPS itself may be a power interruption. This paper provides multifunctional converter of using single phase UPS. The proposed UPS can supply the clean power to the load without polluting the mains power system. The multi-functional converter provides battery charging, var compensation and harmonic suppression simultaneously. It was simulated to verify this work.