• The Journal of the Acoustical Society of Korea
• /
• v.26 no.7
• /
• pp.353-360
• /
• 2007

Rapid urbanization and population increasing are making a high-rise residential building and high-density residential area. According to spacial concentration of population is occurred road traffic noise problem. Now we are popularly using almost only noise barrier installation, but it makes many disfunctions such as poor landscape, low noise barrier performance and crimes. The purpose of this research is to figure out which is best method one the traffic noise management. Alternative are composed to building layout type ($30^{\circ},\;90^{\circ},\;180^{\circ}$), separation between road and residential building, noise barrier types(noise barrier only, noise barrier and forests and etc). The noise barrier are shown to reduce barrier and building layout angle $30^{\circ}$ position is the best comparing with horizontal and vertical layouts. The gab distance is decreased approximately noise level 5dB(A). We figured out there are noise important method except noise barrier wall and it was analyzed how much decreased. This can be very useful before making a road planning and residential building design.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.8
• /
• pp.694-701
• /
• 2018

Civil aircraft noise certification standard is based on the ICAO Annex 16 Vol. 1. And, the standard uses A-Weighted SPL, EPNL and SEL method depending on the aircraft category. Korean noise standards, KAS 36 and other nation's CS 36 and FAR 36 noise standards were developed and revised according to the international noise standards, ICAO Annex 16. And, the national noise requirements are equivalent each other. The small airplane noise certification requires only take-off noise level with A-Weighted SPL in dB(A) unit. The first Korean aircraft noise certification was performed for the KC-100 certification in August 2012 with Korean authority and U.S. FAA. The noise certification requires much knowledge and experience in flight tests and noise data processing. In this study, the noise test requirements, test conditions and data correcting methods are shown with the test examples.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.6 no.8
• /
• pp.1297-1304
• /
• 2002

The phase locked oscillator having a low phase noise and high output in Ku-band was designed. To obtain the low phase noise and high output characteristics of oscillator, the nonlinear equivalent circuits of p-HEMT was analyzed by TOM method and we have decided the trade-off bias point between the low phase noise and the output power of oscillator. The designed phase locked oscillator with prescaler for stable operation, experiment results exhibits output power of 1003m with phase noise in the phase locked state of -824BC/HB at 10mz offset from 13.250Hz, and simulation result of 1003m output power in the phase noise -840Bc/Hz at 10KHz offset frequency respectively. a good agreement has been obtained between simulations and experiments results.

• Journal of IKEEE
• /
• v.17 no.4
• /
• pp.559-563
• /
• 2013

This paper analytically proves the equivalence between two main oscillator phase noise theories, which are based on the ISF, and Floquet vector, respectively. For this purpose, this study obtains the power spectral density matrix from the ISF-based phase noise theory. As a result, one can prove that the power spectral density matrix obtained from the ISF-based phase noise theory is essentially equivalent to the power spectral density matrix presented by the Floquet vector-based phase noise theory, which manifests the equivalence of the two main theories. This study is intended to provide deeper insight into the relations between the two main theories.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.12
• /
• pp.4036-4043
• /
• 1996

When a high-speed railway train enters a tunnel, a compression wave is generated ahead of the train and propagates along the tunnel, compressing and accelerating the rest air in front of the wave. At the exit of the tunnel, an impulsive wave is emitted outward toward the surrounding, which causes a positive impulsive noise like a kind of sonic boom produced by a supersonic aircraft. With the advent of high-speed train, such an impulsive noise can be large enough to cause the noise problem, unless some attempts are made to alleviate its pressure levels. In the purpose of the impulsive noise reduction, the present study tested the effect of porous walls on the compression wave propagating into a model tunnel. Experimental results were obtained using a shock tube with an open end. The results showed that the cavity/porous wall is very effective for the compression wave with a large nonlinear effect. The porosity of 30% is most effective for attenuation and pressure gradient reduction of the compression wave front. Also the impulsive noise reduction increases with increasing the length and height of the cavity, compared with the tunnel equivalent diameter.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.12 no.5
• /
• pp.577-584
• /
• 2009

Fusion of decisions in wireless sensor networks having flexibility on energy efficiency is studied in this paper. Two representative distributions, the generalized Gaussian and $\alpha$-stable probability density functions, are used to model non-Gaussian noise channels. By incorporating noise channels into the parallel fusion model, the optimal fusion rules are represented and suboptimal fusion rules are derived by using a large signal-to-noise ratio(SNR) approximation. For both distributions, the obtained suboptimal fusion rules are same and have equivalent form to the Chair-Varshney fusion rule(CVR). Thus, the CVR does not depend on the behavior of noise distributions that belong to the generalized Gaussian and $\alpha$-stable probability density functions. The simulation results show the suboptimality of the CVR at large SNRs.

• Journal of electromagnetic engineering and science
• /
• v.6 no.1
• /
• pp.30-35
• /
• 2006

This paper describes fully integrated low phase noise MMIC voltage controlled oscillators(VCOs). The Asymmetrical Inductance Tank VCO(AIT-VCO), which optimize the shortcoming of the previous tank's inductance optimization approach, has lower phase noise performance due to achieving higher equivalent parallel resistance and Q value of the tank. This VCO features an output power signal in the range of - 11.53 dBm and a tuning range of 261 MHz or 15.2 % of its operating frequency. This VCO exhibits a phase noise of - 117.3 dBc/Hz at a frequency offset of 100 kHz from carrier. A phase noise reduction of 15 dB was achieved relative to only one spiral inductor. The AIT-VCO achieved low very low figure of merit of -184.6 dBc/Hz. The die area, including buffers and bond pads, is $0.9{\times}0.9mm^2$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.768-771
• /
• 2004

항공기 소음평가 방법에 있어 전혀 다른 소음특성을 갖는 군용 항공기 소음과 민간 항공기 소음을 환경부에서 고시한 소음 진동공정 시험방법에 의거하여 소음을 측정하고 평가하는데는 많은 문제점이 뒤따른다. 따라서 본 연구에서는 민간 항공기와 군용 항공기 소음의 측정 및 평가방법에 대한 문제점들을 고찰하였다. 연구결과로 부터, 민간 항공기나 군용 항공기의 정확한 소음측정을 위해서는 동특성을 빠름(Fast)으로 설정하여 측정하는 것이 바람직한 것으로 확인되었다. 또한 등가 소음도를 측정하여 항공기 소음을 평가하는 방식은 민간 항공기 소음평가시에는 적절하지만, 이를 군용 항공기 소음에 적용하여 평가할 때에는 상당한 오차를 포함하는 것으로 조사되었다. 그리고 군용 항공기 이 착륙지점에서의 소음 지속시간이 대부분 30초를 초과하는 것으로 조사되었기 때문에, 군용 항공기 소음평가시에는 지속시간에 대한 보정이 반드시 반영되어야 할 것으로 사료된다.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.43 no.12 s.354
• /
• pp.23-32
• /
• 2006

Fast and accurate power bus design (FAPUD) method for multi-layers high-speed digital boards is devised for the power supply network design tool for accurate and precise high speed board. FAPUD is constructed, based on two main algorithms of the PBEC (Path Based Equivalent Circuit) model and the network synthesis method. The PBEC model exploits simple arithmetic expressions of the lumped 1-D circuit model from the electrical parameters of a 2-D power distribution network. The circuit level design based on PBEC is carried with the proposed regional approach. The circuit level design directly calculates and determines the size of on-chip decoupling capacitors, the size and the location of off-chip decoupling capacitors, and the effective inductances of the package power bus. As a design output, a lumped circuit model and a pre-layout of the power bus including a whole decoupling capacitors are obtained after processing FAPUD. In the tuning procedure, the board re-optimization considering simultaneous switching noise (SSN) added by I/O switching can be carried out because the I/O switching effect on a power supply noise can be estimated over the operation frequency range with the lumped circuit model. Furthermore, if a design changes or needs to be tuned, FAPUD can modify design by replacing decoupling capacitors without consuming other design resources. Finally, FAPUD is accurate compared with conventional PEEC-based design tools, and its design time is 10 times faster than that of conventional PEEC-based design tools.

• Environmental Analysis Health and Toxicology
• /
• v.29
• /
• pp.6.1-6.6
• /
• 2014

Objectives Hospitalized patients are vulnerable to sleep disturbances because of environmental stresses including noise. While most previous studies on hospital noise and sleep have been performed for medical machines in intensive care units, there is a limited data for patients hospitalized in medical wardrooms. The purpose of present study was to measure noise level of medical wardrooms, identify patient-perceived sources of noise, and to examine the association between noise levels and sleep disturbances in hospitalized patients. Methods Noise dosimeters were used to measure noise level in 29 inpatient wardrooms at a university hospital. Sleep pattern and disturbance were assessed in 103 hospitalized patients, using the Pittsburgh Sleep Quality Index (PSQI) and Leeds Sleep Evaluation Questionnaire. Results The mean equivalent continuous noise level for 24 hours was 63.5 decibel A (dBA), which was far higher than 30 dBA recommended by the World Health Organization for hospital wardrooms. Other patients sharing a room were perceived as the most common source of noise by the patients, which was usually preventable. Of the patients in the study, 86% had bad sleep as assessed by the PSQI. The sleep disturbance was significantly correlated with increasing noise levels in a dose response manner. Conclusions Systemic organizational interventions are needed to keep wardrooms private and quiet to reduce sleep disturbance.