• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.4
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• pp.436-442
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• 2016

This paper presents the torsional vibration isolation performance evaluation of a centrifugal pendulum absorbers (CPAs) that has a continuously varying resonance frequencies proportional to engine firing (excitation) order. CPAs are commonly used to suppress torsional vibrations in rotating machinery and internal combustion engines. In this study, they are employed on the current spring type torsional damper inside a torque converter of automotive vehicle. To evaluate the effectiveness of designed resonance tuning order, the torsional vibration transmissibility based on torque measurements with respect to different engine firing orders is experimentally measured with a lower-inertia dynamometer. The torsional vibration transmissibility with respect to different frequencies with engine order of 2 is also evaluated. It has been demonstrated that the significant vibration reduction over operational frequency range of interest can be achieved by attaching simple pendulums. Future research direction includes the study on theoretical analysis, improved design of pendulum etc.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.209-218
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• 2004

The purpose of this paper is to suggest a practical and simple method for the identification of the joint mechanical properties and to apply it to human knee joints. The passive moment at a joint was modeled by three mechanical parts, that is, a gravity term, a linear damper term and a nonlinear spring term. Passive pendulum tests were performed in 5 fat and 5 thin men. The data of pendulum test were used to identify the mechanical properties of joints through sequential quadratic programming (SQP) with random initial values. The identification was successful where the normalized root-mean-squared (RMS) errors between the simulated and experimental joint angle trajectories were less than 10％. The parameter values of mechanical properties obtained in this study agreed with literature. The inertia, gravity and the damping constant were greater at fat men, which indicates more resistance to body movement and more energy consumption fer fat men. The suggested method is noninvasive and requires simple setup and short measurement time. It is expected to be useful in the evaluation of joint pathologies.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11c
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• pp.1711-1714
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• 2003

고객대응시스템을 도입 및 활용하는 진자상거래 기업들이 점차 증가하고 있는 추세이다. 그러나, 고객대응은 수동적인 서비스모델이라는 한계 때문에 고객의 서비스 만족이라는 측면에서 볼때 전통적거래와 비교하여 부족한 면이 상당수 지적되고 있다. 본 논문에서는 지적되는 문제를 해결하기 위한 확장모델로서 고객반응유도시스템을 제시 및 기술하고 제한된 조건에서 고객의 다중의사정보가 발생할 경우에 대한 처리기법에 대하여 초점을 맞춘다. 제안하는 기법은 관련 기업에서 적은 노력을 통해서 손쉽게 적용 및 응용할 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.7
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• pp.944-950
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• 1993

Diodes and GaAs have been commonly used in a mixer design until recently. However, diodes are not preferred to use at the front-end of DBS receiver due to the conversion loss large noise. HEMT has larger conversion gain and better noise characteristics comparing with GaAs MESFET. This paper describes the design procedure, structure, and performance of a mixer, utilizaing HEMT designed by OKI Co. . A mixer configuration in which the local oscillator(LO) signal is applied to the gate is used. When the LO power is 0.01 dBm, the conversion gain of 3.7dB is obtained at IF and the 3 dB bandwidth is 400MMz.

• Journal of Advanced Navigation Technology
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• v.16 no.4
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• pp.703-708
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• 2012

This paper proposes the improvement of control performance in the wheeled inverted mobile robot system. and describes the modeling of a wheeled inverted pendulum type mobile robot driven by two different wheels for the position and velocity control. The system is sensitive on the parameter variation, therefore control signal should change to maintain desired state of the system in every instant. we designed proportional-plus-integral controller for our system, After linearization, the system was still unstable, throughout stability analysis of the system, we designed the values of the gains of a proportional-plus-integral controller. From the experimental results, we can find that the performance of the proposed method is better than of the manual tuning method.

• Journal of IKEEE
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• v.26 no.4
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• pp.681-685
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• 2022

Including the COVID-19 crisis, humanity is constantly exposed to viral infections, and efforts are being made to prevent the spread of infection by quickly isolating infected people and tracing contacts. Passive epidemiological investigations that confirm contact with an infected person through contact have limitations in terms of accuracy and speed, so automatic tracking methods using various digital technologies are being proposed. This paper verify contact by utilizing Bluetooth Low Energy (BLE) technology and present an algorithm that identifies close contact through analysis and correction of RSSI (Received Signal Strength Indicator) values. Also, propose a system that can prevent the spread of viruses in a centralized server structure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.2
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• pp.193-198
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• 2022

Recently, place that you need to check wearing mask and body temperature to prevent the proliferation of COVID-19 increased. But these things often measured by man manually or by machine one by one, result may be different by measuring ways, so it wastes workforce. Also, the machine generally just measures the highest temperature of the face, criteria for fever can't be trusted too. A bottleneck may occur due to crowding of people at the entrance, and because most of the measurement sites are at one entrance, it is inconvenient to track the movement of COVID-19 Confirmed cases. Thus, in this study, we intend to propose a method for suppressing the spread of infection by automatically classifying and displaying in real time using camera, thermal camera, Haar Cascade, and result selection algorithm.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.2 s.42
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• pp.37-46
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• 2005

To date, many viable smart base isolation systems have been proposed and investigated. In this study, a novel friction pendulum system (FPS) and an MR damper are employed as the isolator and supplemental damping device, respectively, of the smart base isolation system. A fuzzy logic controller (FLC) is used to modulate the MR damper because the FLC has an inherent robustness and ability to handle non linearities and uncertainties. A genetic algorithm (GA) is used for optimization of the FLC. The main purpose of employing a GA is to determine appropriate fuzzy control rules as well to adjust parameters of the membership functions. To this end, a GA with a local improvement mechanism is applied. This method is efficient in improving local portions of chromosomes. Neuro fuzzy models are used to represent dynamic behavior of the MR damper and FPS. Effectiveness of the proposed method for optimal design of the FLC is judged based on computed responses to several historical earthquakes. It has been shown that the proposed method can find optimal fuzzy rules and the GA optimized FLC outperforms not only a passive control strategy but also a human designed FLC and a conventional semi active control algorithm.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.1 s.41
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• pp.61-70
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• 2005

Shaking table tests are carried out on a single-degree-of-freedom mass that is equipped with a hybrid base isolation system. The isolator consists of a set of four specially-designed friction pendulum systems (FPS) and a magnetorheological (MR) damper. The structure and its hybrid isolation system are subjected to various intensities of near- and far-fault earthquakes on a large shake table. The proposed fuzzy controller uses feedback from displacement or acceleration transducers attached to the structure to modulate resistance of the semi-active damper to motion. Results from several types of passive and semi-active control strategies are summarized and compared. The study shows that a combination of FPS isolators and an adjustable MR damper can effectively provide robust control of vibration for a large full-scale structure undergoing a wide variety of seismic loads.

• Journal of Trauma and Injury
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• v.19 no.2
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• pp.126-134
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• 2006

Purpose: The aim of this study was to determine the kinematical characteristics of the pendular and the translational movements of each cervical vertebra at flexion and extension for understanding the mechanism of injury to the cervical spine. Methods: Twenty volunteers, young men (24~37 years), with clinically and radiographically normal cervical spines were studied. We induced two directional passive movements and then took X-ray pictures. The range of pendular movement could be measured by measuring the variation of the distance between the center point of two contiguous cervical vertebrae, and the range of translational movement could be measured by measuring the variation of the shortest distance between the center point of a vertebra and an imaginary line connecting the center points of two lower contiguous cervical vertebrae. The measurements were done by using a picture archiving and communicating system (PACS). Results: The total length of all cervical vertebrae in the neutral position was, on average, 133.66 mm, but in both flexion and extension, the lengths were widened to 134.83 mm and 134.79 mm, respectively. The directions of both the pendular and the translational movements changed at the $2^{nd}$ cervical vertebra, and the ranges of both movements were significantly larger from the $5^{th}$ cervical vertebra to the $7^{th}$ cervical vertebra for flexion and combined flexion and extension motion (p<0.05). Conclusion: The kinematical characteristics for flexion and extension motions were variable at each level of cervical vertebrae. The $1^{st}$ and the $2^{nd}$ cervical vertebrae and from the $5^{th}$ to the $7^{th}$ cervical vertebrae were the main areas of cervical spinal injury. This shows, according to "Hook's law," that the tissues supporting this area could be weak, and that this area is sensitive to injury.