• Computational Structural Engineering : An International Journal
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• v.1 no.2
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• pp.89-96
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• 2001

A study on the topology optimization of a Hard-Disk-Driver(HDD) actuator arm is presented. The purpose of the present wert is to increase the natural frequency of tole first lateral mode of the HDD actuator arm under the constraint of total moment of inertia, so as to facilitate the position control of the high speed actuator arm. The first lateral mode is an important factor in the position control process. Thus the topology optimization for 2-D model of the HDD actuator arm is considered. A new objective function corresponding to multieigenvalue optimization is suggested to improve the solution of the eigenvalue optimization problem. The material density of the structure is treated as the design variable and the intermediate density is penalized. The effects of different element types and material property functions on the final topology are studied. When the problem is discretized using 8-node element of a uniform density, tole smoothly-varying density field is obtained without checker-board patterns incurred. AS a result of 7he study, an improved design of the HDD actuator arm is suggested. Dynamic characteristics of the suggested design are compared computationally with those of the old design. With the same amount of the moment of inertia, the natural frequency of the first lateral mode of the suggested design is subsequently increased over the existing one.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.3
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• pp.223-228
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• 2015

This paper analyses the torque characteristics of the shoulder and elbow joints of a humanoid robot arm that is useful for an object lifting and transferring task instead of human beings. For the purpose, some typical human lifting behaviors are considered, and various simulations for lifting and transferring an object have been performed by employing a humanoid robot arm having a simple configuration of shoulder and elbow joints. Through the simulation, it is shown that the torque patterns and ranges of the shoulder and elbow joints required for such a humanoid lifting and transferring task can be found earlier in the design of a humanoid robot arm. As a result, this effort is useful for us to design an effective robot arm.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.409-412
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• 2011

본 논문에서는 Xen-ARM 기반의 가상화 환경에서 실시간 게스트 운영체제의 I/O를 지원하기 위한 방법을 제안한다. Xen-ARM 하이퍼바이저는 서버 환경에서 주로 사용되는 Xen 가상화 기법을 모바일 구조인 ARM에서 구현한 것으로, 분할 드라이버 모델과 크레딧 스케줄러를 지원한다. 하지만, 이러한 두 가지 특성은 I/O 처리 지연의 주요 원인이 된다. 특히, 장치 드라이버와 사용자 태스크의 실행 중에 하이퍼바이저의 도메인 간 스위칭이 필요하므로, 특정 시간으로 I/O 처리 지연을 제한하기 대단히 어렵다. 본 논문에서는 게스트 운영체제의 수정을 통해 I/O 처리 지연을 제한하는 기법을 제안한다. 게스트 운영체제는 현재 실행되는 태스크의 특성을 Xen-ARM 하이퍼바이저에게 간접적으로 전달하여, 전체 시스템의 모든 태스크에 대하여 우선순위를 부여하며, 하이퍼바이저의 스케줄러에서 인터럽트 처리를 위해 가장 응급한 태스크 실행을 스케줄링 할 수 있도록 한다. 제안하는 기법은 실험을 통해, I/O를 처리하는 도메인의 1ms 이상의 처리시간이 84%에서 99%까지 줄어들 수 있음을 보인다.

• Journal of Ocean Engineering and Technology
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• v.27 no.1
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• pp.43-50
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• 2013

This paper presents a structural design review of a marine loading arm used for the fluid transfer of a liquid cargo from a ship or offshore plant. The marine loading arm is installed on a ship, offshore plant, or jetty in order to load or unload liquid cargo such as crude oil, liquefied natural gas (LNG), chemical products, etc. The structural design of this marine loading arm is obliged to comply with the design and construction specifications regulated by the oil companies and international marine forum (OCIMF). In this paper, the structural safety of the initial design for the marine loading arm is evaluated for the design load conditions required by various operational modes. The evaluated results based on a finite element analysis (FEA) are reviewed in relation to the OCIMF specifications.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.4
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• pp.69-75
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• 2009

Recently developed automotive components are getting lighter providing a higher fuel efficiency and performance. Following the current trend, this study proposes a structural optimization method for the lower control arm installed at the front side of a Vehicle. Lightweight design of lower control arm can be achieved through design and material technology. In this research, the shape of lower control arm was determined by applying the optimization technology and aluminum was selected as a steel-substitute material. Strength performance is the most important design requirement in the structural design of a control arm. This study considers the static strength in the optimization process. For the optimum design, the durability analysis is performed to predict its fatigue life. In this study, the kriging interpolation method is adopted to obtain the minimum weight satisfying the strength constraint. Optimum designs are obtained by the in-house program, EXCEL-Kriging. Also, based on the optimum model obtained for the static strength, the optimization of Index of Fatigue Durability is carried out to get th optimum fatigue performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2A
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• pp.188-194
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• 2007

In order to become ubiquitous world, the compatibility of wireless machines has become the significant characteristic of a communication terminal. Thus, SDR is the most necessary technology and standard. However, among the environment which has different communication protocol, it's difficult to make a terminal with only hardware using ASIC or SoC. This paper suggests the processor that can accelerate several communication protocol. It can be connected with main-processor, and it is specialized PHY layer of network The C-program that is modeled with the wireless protocol IEEE802.11a and IEEE802.11b which are based on widely used modulation way; OFDM and CDM is compiled with ARM cross compiler and done simulation and profiling with Simplescalar-Arm version. The result of profiling, most operations were Viterbi operations and complex floating point operations. According to this result we suggested a co-processor which can accelerate Viterbi operations and complex floating point operations and added instructions. These instructions are simulated with Simplescalar-Arm version. The result of this simulation, comparing with computing only one ARM core, the operations of Viterbi improved as fast as 4.5 times. And the operations of complex floating point improved as fast as twice. The operations of IEEE802.11a are 3 times faster, and the operations of IEEE802.11b are 1.5 times faster.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.3
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• pp.236-242
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• 2009

When two-link flexible arm is rotated about an joint axis, transverse vibration may occur. In this paper, vibration dynamics of flexible robot arm is modeled by using Bernoulli-Euler beam theory and Lagrange equation. Using the fact that matrix $\dot{D}$-2C is skew symmetric, new controllers which have a simplified structure with less computational burden is proposed. Lyapunov stability theory is applied to achieve a stable deterministic nonlinear controller for the regulation of joint angle.

• Journal of the Korean Society of Industry Convergence
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• v.14 no.4
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• pp.167-172
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• 2011

This paper investigated optimal design for slim wall mount arm for flat TV. Recently the number of flat TV sets in use went on increasing in TV market. As the flat TV sets are getting common, consumers came to need another requirements like aesthetic factor besides display performances. As the new TV sets tend to be slimmer due to aesthetic design, Wall mount also requires to be slimmer for aesthetic balance. Slim structures, however, are vulnerable to structural rigidity. In this study, slim wall mount arm has been designed by 3D CAD and DOE (Design of Experiments) and finite element analysis for optimal structural design were carried out to determine the design variables for minimize working stress of wall mount arm. Finally two optimal design conditions were selected through DOE and FEM and one of those was chosen under constraint of minimizing blanking developed length.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.423-426
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• 2004

본 논문에서는 저 전력 마이크로프로세서를 개발하기 위해 ARM7 마이크로프로세서와 명령어 호환을 갖는 32비트 RISC 구조의 마이크로프로세서를 설계하였다. 저 전력 ARM7 마이크로프로세서 IP 구현을 위하여 새로운 정수 나눗셈 명령어를 정의하고 이를 적용하는 회로를 설계하여 제수가 피제수보다 큰 경우 6.4nW, 그 이외의 경우에는 76.5 nW를 소모하여 기존의 방법보다 $140{\~}860\%$ 까지 개선되었음을 측정하였다. 또한 Multi-cycle 명령어 발생시 Prefetch에 의한 전력 소모를 줄이기 위하여 명령어의 condition code를 미리 결정함으로써 $50\%$의 prefetch 동작 횟수를 줄였다. 그 결과 저 전력 파이프라인의 경우에는 1.943mW/1MHz의 소비 전력이 측정되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1149-1155
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• 1999

This paper presents a narrow-band orthomode transducer(OMT) based on waveguide to waveguide transitions which can separate two linearly polarized orthogonal modes. This operates in the range 120Hz-13GHz frequency band. It consists of two parts, main arm and side arm. Stepped transformers are designed and an inductive post is inserted to improve the characteristics of the transmission loss and isolation. This paper also presents results from fabricated OMT These results show that the transmission loss is less than 1dB and the isolation between the ports for the OMT is above 20dB.