• 한국자동차공학회논문집
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• 제5권1호
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• pp.38-48
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• 1997

A method for performing kinematic design sensitivity analysis of vehicle suspension systems is presented. For modeling of vehicle suspensions, the multibody dynamic formulation is adopted, where suspensions are assumed as combination of rigid bodies and ideal frictionless joints. In a relative joint coordinate setting, kinematic constraint equations are obtained by imposing cut-joints that transform closed-loop shape suspension systems into open-loop systems. By directly differentiating the constraint equations with respect to kinematic design variables, such as length of bodies, notion axis, etc., sensitivity equations are derived. By solving the sensitivity equations, sensitivity of static design factors that can be used for design improvement, can be obtained. The validity and usefulness of the method are demonstrated through an example where kinematic sensitivity analysis of a MacPherson strut suspension of performed.

• The Journal of the Acoustical Society of Korea
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• 제24권3E호
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• pp.109-114
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• 2005

In this paper, we present a phase coherent all-digital transceiver for underwater acoustic communication, which allows the system to reduce complexity and increase robustness in time variant underwater environments. It is designed in the digital domain except for transducers and amplifiers and implemented by using a multiple digital signal processors (DSPs) system. For phase coherent reception, conventional systems employed phase-locked loop (PLL) and delay-locked loop (DLL) for synchronization, but this paper suggests a frame synchronization scheme based on the quadrature receiver structure without using phase information. We show experimental results in the underwater anechoic basin at MOERI. The results show that the adaptive equalizer compensates frame synchronization error and the correction capability is dependent on the length of equalizer.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.717-718
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• 2013

CMOS로 구성된 전압-제어 발진기의 채널 폭과 길이가 변화하면, 입력 전압에 따른 출력 주파수가 변화할 것이다. 본 논문에서는 FLL(Frequency Locked Loop) 회로의 구성 요소로 사용되는 전압-제어 발진기의 채널 폭 변화에 따른 전기적인 특성 변화를 시뮬레이션을 통하여 살펴보고자 한다. 그리고 변화하는 채널 폭에 따른 전압-제어 발진기의 신뢰성 특성을 향상하기 위한 방안을 살펴보고자 한다.

• 대한기계학회논문집
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• 제19권9호
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• pp.2399-2411
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• 1995

Crane operation for transporting heavy loads inherently causes swinging motion at the loads due to crane's acceleration or deceleration. This motion not only lowers the handling safety but also slows down the handling process. To complement such a problem, Korea Atomic Energy Research Institute(KAERI) has designed several anti-swing controllers using open loop and closed loop approaches. They are namely a pre-programmed feedback controller and a fuzzy controller. These controllers are implemented on a 1-ton crane system at KAERI and their control performances are compared. Test operations show that the new controllers are superior to that of conventional cranes in terms of robustness to the disturbances and adaptation capability to the change of rope length.

• ETRI Journal
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• 제19권3호
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• pp.98-115
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• 1997

The architecture of the CDMA mobile system (CMS) is developed based on three function groups - service resource, service control, and service management groups. In this paper, the CMS architecture is discussed from the point of view of implementing these functions. The variable length packets are used for transmission. The synchronization clock signals are derived form the GPS receiver. The open loop and closed loop techniques are used for the power control. The internationally accepted signaling and network protocols are employed. The call control for the primary services in designed to provide efficient mobile telecommunication services. The softer handoff is implemented in one card. The mobile assisted handoff and the network assisted handoff are employed in the soft and hard handoffs. The authentication is based on the secret data which includes random numbers. The management functions, which include the location management, resource management, cell boundary management and OAM management, are implemented to warrant the system efficiency, maximum capacity and high reliability. The architecture ensures that the CMS is flexible and expandable to provide subscribers with economic and efficient system configuration. The dynamic power control, adaptive channel allocation. and dynamic cell boundary management are recommended for future work.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.63-64
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• 2006

In this paper, the open loop antenna using a strip-conductor for an RFID reader at dual-band frequency(910MHz, 2.45GHz) is proposed. The impedance is matched by varying the antenna parameters such as the length of strip-conductor and the gap of between two strip-conductors. Return loss and gain of designed antenna are -11.919dB, 2.5dBi at 910MHz, and -15.766dB, 5.65dBi at 2.45GHz, respectively.

• 한국생산제조학회지
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• 제23권5호
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• pp.450-455
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• 2014

Domestic power plants have consistently been developed over the years in industrially developed nations with high standards of living. Considering the power plant development strategy, design efficiency is of upmost importance. Therefore, an improper design directly affects the power plant's risk management plan and the potential risks of the piping system. Therefore, in this study, research is intended to be carried out to allow efficient power plant operation, through optimization of the design of the piping system. The purpose of the study is to confirm economic feasibility by changing the piping loop design, expanding the length of pipe loops, and to investigate the thermal stress influence on the piping system through simulations of systems similar in condition to those currently used in existing plants in Korea.

• 한국통신학회논문지
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• 제22권5호
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• pp.990-1006
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• 1997

This paper describes an interface function and its performance assessment for high-bit-rate digital subscriber line (HDSL) under ATM. The interface of HDSL function of ATM system was achieved by HDSL subscriber physical layer board assembly(HSPA) which was modeled as design standard for ATM. We have presented a new worst case of subscriber line conditions from existing results of investigations on impairments such as crosstalk, impulse noise, longitudinal, power line noise and others. We have measured the maximum service loop length available by HDSL, and found that HSPA, at a 2.048Mbps data transmission, is possible within a carrier serving area(CSA) under the worst case loop noise conditions at an error rate or 10$^{-7}$ on a two coordinated unshielded twisted pairs in the presense of impairments. We conclude tht, in terms of a performance-per-lin simulator, the HSPA is an excellent candidate for HDSL implementation under ATM.

• 대한안전경영과학회지
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• 제18권4호
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• pp.179-183
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• 2016

The purposes of this research are to modelize test system of SM TESTING by ARENA, software, input several items of specimen's testing process, resources of system and transfer loop, etc, give a hypothesis and then, obtain results reducing the efficiency of the whole system finally by overload of specific facilities in the testing system through the simulation so as to obtain several materials such as specimen and testing facility, transfer loop, etc. by simple and various forms without any necessity of numerical modelization. It will add facilities of over load and reduce facilities with low operation rate, so increase the efficiency of the system.

• Structural Engineering and Mechanics
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• 제32권4호
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• pp.501-516
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• 2009

This paper aims to study the large deflections of variable-arc-length elastica subjected to the terminal forces (e.g., axial force and torque). Based on Kirchhoff's rod theory and with help of Euler parameters, the set of nonlinear governing differential equations which free from the effect of singularity are established together with boundary conditions. The system of nonlinear differential equations is solved by using the shooting method with high accuracy integrator, seventh-eighth order Runge-Kutta with adaptive step-size scheme. The error norm of end conditions is minimized within the prescribed tolerance ($10^{-5}$). The behavior of VAL elastica is studied by two processes. One is obtained by applying slackening first. After that keeping the slackening as a constant and then the twist angle is varied in subsequent order. The other process is performed by reversing the sequence of loading in the first process. The results are interpreted by observing the load-deflection diagram and the stability properties are predicted via fold rule. From the results, there are many interesting aspects such as snap-through phenomenon, secondary bifurcation point, loop formation, equilibrium configurations and effect of variable-arc-length to behavior of elastica.