• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.513-518
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• 2013

The purpose of vehicle horn sound is for warning to pedestrians. In the past, the main development factor is to match the regulation level. But nowadays perceived quality is more important than level itself. In this study, we measure variety horn sound and evaluate its signals through the jury evaluation aimed at making horn sound quality index. Each contribution of the noise path for sound quality is identified and the target values and methods for implementing the luxurious horn sound are suggested. Finally, we developed, horn component and improve horn mounting condition for luxurious horn sound.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.10
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• pp.968-975
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• 2010

The high interest for the ground vibrations which is caused by the train service is risen. When the trains are passed, a serious force is applied to ground and the caused vibration is propagated to the area of the building by the ground and rocks. This vibration comes to feel in the residents with the direct vibration, it is radiated in sound. The caused vibration and radiated sound affect the human's life, and this vibration brings about the operation interruption of the equipment which is sensitive to the vibration, or will bring about the structural damage of the building. In this study, the effect of the vibrations caused by the passing trains on the railway station and buildings is investigated by vibration measurement. Indoor and outdoor measurement is carried out by each trains.

• Safety and Health at Work
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• v.4 no.2
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• pp.77-83
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• 2013

There is still a considerable burden of occupational diseases and injuries in the world. It is not well known which interventions can effectively reduce the exposures at work that cause this burden. The objective of this article is to summarize evidence from systematic reviews of interventions to prevent occupational diseases and injuries. We included systematic reviews of interventions to reduce the incidence of work-related cancer, dust-related diseases, occupational asthma, chronic obstructive pulmonary disease, noise induced hearing loss, back pain, and occupational injuries. We searched Medline and Embase with predefined search strategies to locate systematic reviews of these interventions. We found 23 systematic reviews of which the results are also applicable to low- and middle income countries. Effective measures to reduce exposure leading to work-related cancer, dust-related diseases, asthma, chronic obstructive pulmonary disease, noise, and injuries are available. However, better implementation of these measures is needed. Regulation, enforcement of regulation, and incentives for employers are effective interventions to achieve this goal. There is evidence that feedback and rewards for workers help in reducing occupational injuries. There is no evidence in many studies that back pain can be prevented. Personal protective equipment technically has the potential to reduce exposure but this is difficult to put into effect. There is no evidence in the studies regarding the effectiveness of education and training, preventive drugs, or health examinations. There is evidence that the implementation of technical measures enforced by regulation can prevent occupational diseases and injuries. For other interventions such as education or health examinations, there is no evidence that supports their effectiveness. More systematic reviews are needed in the area of injury prevention.

• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.569-576
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• 2007

Ventricular Assist Device(VAD) has switched its goal from a short-tenn use for bridge-to-transplantation to a long-tenn use for destination therapy, With this goal, the importance of long-tenn reliability gets more interests and importances, H-VAD is an portable extracorporeal biventricular assist device, and adopts an electro-pneumatic driving mechanism. The pneumatic pressure to pump out blood is generated with compression of bellows, and is transmitted in a closed pneumatic circuit through a pneumatic line. The existing pneumatic VAD adopts a air compressor which can generate stable pressures but has defects such as a noise and a size problem. Thus, it is not suitable for being used as a portable device, These problems are covered with adopting a closed pneumatic circuit mechanism with a bellows which has a small size and small noise generation, but it has defects that improper pneumatic setting causes a failure of adequate flow generation. In this study, the pneumatic pressure regulation system is developed to cover these defects of a bellows-type pneumatic VAD. The optimal pneumatic pressure conditions according to various afterload conditions for an optimal flow rate were investigated and the afterload estimation algorithm was developed, The final pneumatic regulation system estimates a current afterload and regulate the pneumatic pressure to the optimal point at a given afterload condition. The afterload estimation algorithm showed a sufficient performance that the standard deviation of error is 8.8 mmHg, The pneumatic pressure regulation system showed a sufficient performance that the flow rate was stably governed to various afterload conditions. In a further study, if a additional sensor such as ultrasonic sensor is developed to monitor the direct movement of diaphragm in a blood pump part, the reliability would be greatly increased. Moreover, if the afterload estimation algorithm gets more accuracy, it would be also helpful to monitor the hemodynamic condition of patients.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.4 no.1
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• pp.32-37
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• 1979

The corona noise level at the place 10m and the frequency 1MHz from the new 345KV transmission line is 72dB in the maximum rain-fall and 63dB due to the wet conductors. The synthesized corona noise level of all 3 phases dominantly depends on the phase which has maximum corona level among them. The measured characteristic of the variation with distance from the line coincided well with the theoretically calculated value in this paper. The corona noise level was the highest level in rainy weather or snow-fall. It takes a few hours, for the corona noise to be stable after a rain-fall or snow-fall. The measured value of the corona noise level corresponds quite well with the formula for the corona noise level revision. It was necessary to quantize S/N ratio into radio reception quality for the radio interference due to the transmission line. Some regulations for radio reception quality were defined through long term experiments and ratings by ITU, IEEE comittee, NHK in Japan and others. Fixing our own regulation about radio reception quality should be required.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.1
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• pp.12-17
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• 2014

In this paper, we propose a controller capable of reducing the effect of measurement errors under AC and DC noise. Typically, the control system measures data through a sensor. If sensor noise is included in a controller via the feedback channel, the signal is distorted and the entire system cannot work normally. Therefore, some appropriate action to counter the measurement error effect is essential in the controller design. Our controller is equipped with a gain-scaling factor and a compensator to reduce the effect of measurement error in the feedback signal. Also, we use a switching control strategy to enhance the performance of the controller regarding convergence speed. Our proposed controller can therefore effectively reduce the AC and DC noise of the sensor. We analyze the proposed controller by Laplace transform technique and our control method is verified via MATLAB simulation.

• International Journal of Automotive Technology
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• v.2 no.2
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• pp.39-45
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• 2001

Hydrogen is seen as one of the important energy vectors of the next century. Hydrogen as a renewable energy source, provides the potential for a sustainable development particularly in the transportation sector. Hydrogen driven vehicles reduce both local as well as global emissions. The laboratory of transporttechnology (University of Gent) converted a GM/Crusader V-8 engine for hydrogen use. Once the engine is optimised, it will be built in a low-floor midsize hydrogen city bus for public demonstration. For a complete control of the combustion process and to increase the resistance to backfire (explosion of the air-fuel mixture in the inlet manifold), a sequential timed multipoint injection of hydrogen and an electronic management system is chosen. The results as a function of the engine parameters (ignition timing. injection timing and duration, injection pressure) we given. Special focus is given to topics related to the use of hydrogen as a fuel: ignition characteristics (importance of electrode distance), quality of the lubricating oil (crankcase gases with high contents of hydrogen), oxygen sensors (very lean operating conditions), noise reduction (configuration and length of inlet pipes). The advantages and disadvantages of a power regulation only by the air to fuel ratio (as for diesel engines) against a throttle regulation (normal gasoline or gas regulation) are examined. Finally the goals of the development of the engine are reached: power output of 90 kW, torque of 300 Nm, extremely low emission levels and backfire-safe operation.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.670-674
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• 1992

This paper presents a velocity regulation scheme for a DC motor subjected to random torque and velocity measurement noises of white noise type as well as unknown constant load torque (bias). The scheme separately estimates an unknown bias in addition to state estimation by the bias-free Kalman Filter, and reflects the effect of the bias estimate to the armature input voltage such that velocity variations be regulated. It is shown via computer simulations that the performance of the present scheme is superior to that of the conventional analog PI regulator.

• Journal of East-Asian Urban History
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• v.2 no.1
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• pp.7-26
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• 2020

Urban pollution has been a problem in China since ancient times. In modern times, pollution was aggravated by industrialization and urbanization and became closely related to people's lives. Shanghai was the industrial center and the most urbanized place of modern China. As a price, it needed to face extremely serious urban pollution, and the treatment of this problem involved all aspects of social life. Noise pollution let foreigners to interpret the Chinese people and the city of Shanghai from a cultural perspective, and let Chinese residents to understand Shanghai and the nation from a civilized perspective. Pollution regulation made Shanghai the first city in modern China to implement overall pollution control and levy environmental protection fees. It also enabled the Chinese to gradually fight for their rights in urban governance. Urban pollution also brought business opportunities; in the highly commercial city of Shanghai, it promoted the development of some industries. The experience of urban pollution and its treatment prompted the people of Shanghai to rethink and re-recognize modern civilization, and also promoted the formation of Shanghai urban community.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.3
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• pp.120-125
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• 2002

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. In the switching-mode power converter, the output voltage is generally controlled by varying the duty ratio of main switch. When a converter operates in steady state, duty ratio of the converter is kept constant. So the power of switching noise is concentrated in specific frequencies. Generally, to reduce the EMI and improve the immunity of converter system, the switching frequency of converter needs to be properly modulated during a rectified line period instead of being kept constant. Random Pulse Width Modulation (RPWM) is performed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300V/1kW with 5%~30% white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.