• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.3 s.96
• /
• pp.320-328
• /
• 2005

Last target of architectural acoustics is that people wish to convey voice effectively from the space adaptively in use purpose in building. But, how exactly through space sound (sound source) that wish to deliver from indoor can be passed method to do quantification and evaluate quantity of sound by method to serve indoor architectural acoustics estimation summer period and methods to estimate definition propose. This Study searches special quality of sound source about MLS signal that is occurred short-answer sound source (pistol sound source) and nondirectional speaker among indoor sound estimation method, and measure and analyzed reverberation time (RT60), definition (C80, D50) by regulation of each ISO 3382 in age place (classroom, hall, gymnasium). Analysis result and sound factor among could know that d of two sound sources converges in measurement error extent about reverberation time (RT60) of analysis incidental and sound factors and value shows change irregularly about sound factor of D50, C80, pistol sound source judged there is problem. Also, could know that problem is happened in deflection except reverberation time is in deflection analysis with wave that measure each in fixed distance in branch. Finally, when differ size of sound source and measure about change of sound pressure level in case measure sound pressure level giving difference about 10 dB, sound factor could know that there is no different effect.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.17 no.5
• /
• pp.134-140
• /
• 2003

In this paper, a hardware implementation of gas flow meter for accuracy improvement and saving repair costs at a field is investigated. An adaptive filter using LMS algorithms for estimating cavity vibration frequencies in noisy environments is also studied. The proposed cavity gas flow meter measures cavity sound signals in gas flow tube using microphone and signal processing systems estimate the cavity vibration frequency from the measured signal. The flow velocity and flow quantity can be calculated using the estimated cavity vibration frequency. Since cavity vibration frequency is corrupted by the environmental noise, an adaptive filter using NLMS algorithms is used for cancelling the environmental noise. Experiments using 1MS32OC32 digital signal processor are performed to show the effectiveness of the proposed system.

• Journal of Distribution Science
• /
• v.15 no.11
• /
• pp.73-82
• /
• 2017

Purpose - This paper aims to investigate a profit maximizing incentive of foreign traders in distributing the KOSPI 200 Futures. Such an incentive may induce unsophisticated retail traders to suffer loss from speculative trading. Since Korean government increased the entry barriers of the market to protect unsophisticated traders, the market size has been decreasing while the proportion of the contract held by foreign traders has been increasing. These on going changes make the market imperfectly competitive, where a profit maximization incentives of foreign traders are expected to grow. In this paper, we attempt to find any evidence of such behavior, thereby providing implications regarding market policy and market efficiency. Research design, data, and methodology - According to Kyle(1985), an informed trader exploits his/her monopoly power optimally in a dynamic context so that he/she makes positive profit, where he/she could conceal his/her trading utilizing noise trading as camouflage. We apply the KOSPI 200 Futures market to the Kyle's model: foreign traders who take into account the effect of his/her trading to maximize expected profits as an informed trader, retail investors as noise traders, and financial institutions as market makers. To find any evidence of monopolistic behavior, we test the variants of trading volume and price data of the KOSPI 200 Futures over the period of 2009 and 2017. Results - First, we find that the price of the KOSPI 200 Futures are more volatile than the price of underlying asset. Second, we find that monopolistic foreign trader's trading order flows are consistent with exploiting his/her monopoly power to maximize profit. Finally, we find that retail investors' trading order flows are inversely consistent with maximizing profit, that is, uninformed retail investors suffer loss continuously in speculative trading against informed traders. Conclusions - Our results show that the quantity of strategic order flows may have a large effect on the price, therefore, resulting the market inefficiency. The results also imply that, in implementing regulations, the depth of the market must be considered to maintain market liquidity, and suggesting interesting research topics regarding the market structure.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.10
• /
• pp.1385-1392
• /
• 2003

An electromagnetic flowmeter(EMF) was developed and its characteristics were compared with a commercial EMF. The developed EMF was designed as the 100 mm nominal diameter. A signal processing circuit was also developed for generating the magnetic field and converting the flow signal to flowrate and flow quantity. In order to obtain a more stable and reliable flow signal, the double magnetizing frequency was adopted for magnetizing the coil of the EMF. For the characterization of the developed EMF, the uncertainty of calibrator was estimated within $\pm$0.5 %. The evaluation procedure of the uncertainty followed the ISO Guide to the Expression of Uncertainty in Measurement. It was found that the flow signals between the electrodes were about $\pm$60-$\pm$300$\mu$V, which were sufficient for the discrimination of flowmeter and the protection of noise. The test results against the calibrator showed the good linearity in the range of 3 ㎥/h and 70 ㎥/h. A commercialized design of the EMF based on the current study will be technically more competitive in domestic and foreign market.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.52 no.5
• /
• pp.211-220
• /
• 2003

The control method of programmable dynamometer for overall test of machine is to load the reference torque which is computed from torque transducer into motor under test. But the torque information detected from torque transducer have a lot of noise when the load torque of meter is a small quantity or changing. Thus, torque transducer must have a low pass filter to detect a definite torque information. But The torque delay generated by filter with torque transducer occur a torque trouble for meter torque of programmable dynamometer. Therefore, this kind of system could not perform dynamic and nonlinear load. In this paper, the control method using the load torque observer without a measure for torque transducer is Proposed. The proposed system improved the problem of the torque measuring delay with torque transducer, and the load torque is estimated by the minimal order state observer based on the torque component of the vector control induction meter. Therefore, the torque controller is not affected by a load torque disturbance. To verify a superiority of the proposed control algorithm, the analysis for a root locus of a conventional control method and the proposed one, and simulation and experiment is performed. Therefore we hope to be extended in industrial application.

• Phonetics and Speech Sciences
• /
• v.7 no.1
• /
• pp.21-26
• /
• 2015

The aim of this study is to synthesize pathological breathy voice and to make a cepstral peak prominence (CPP) table following breathiness ranks by cepstral analysis to supplement reliability of the perceptual auditory judgment task. KlattGrid synthesizer included in Praat was used. Synthesis parameters consist of two groups, i.e., constants and variables. Constant parameters are pitch, amplitude, flutter, open phase, oral formant and bandwidth. Variable parameters are breathiness (BR), aspiration amplitude (AH), and spectral tilt (TL). Five hundred sixty samples of synthetic breathy vowel /a/ for male were created. Three raters participated in ranking of the breathiness. 217 were proved to be inadequate samples from perceptual judgment and cepstral analysis. Finally, 343 samples were selected. These CPP values and other related parameters from cepstral analysis are classified under four breathiness ranks (B0~B3). The mean and standard deviation of CPP is $16.10{\pm}1.15$ dB(B0), $13.68{\pm}1.34$ dB(B1), $10.97{\pm}1.41$ dB(B2), and $3.03{\pm}4.07$ dB(B3). The value of CPP decreases toward the severe group of breathiness because there is a lot of noise and a small quantity of harmonics.

• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.361-364
• /
• 2002

An electromagnetic flowmeter(EMF) was developed and its characteristics were compared with a commercial EMF. The measuring tube of the EMF was basically designed as 100 m diameter. A signal processing circuit was also developed for generating the magnetic field and converting the flow signal to flowrate and flow quantity. To obtain a more stable and reliable flow signal, the double magnetizing frequency was adopted for magnetizing the coil of the EMF For the characterization of EU, the uncertainty of calibrator was estimated within ${\pm}0.5{\%}$, the method of estimation was in accordance with the ISO 17025 recommendation. It was found that the flow signals between the electrodes were about ${\pm}60\;-\;{\pm}300{\mu}V$, which were sufficient for the discrimination of the flowmeter and protecting the noise. The test result against the calibrator, showed the good linearity in the range of $3 m^{3}/h\;and\;70m^{3}/h$. A commercialized design of the EMF will be technically more competitive in domestic and foreign market.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.1273-1278
• /
• 2007

The cement-asphalt mortar is a mixture of cement and asphalt emulsion, and is utilized as a underpouring materials for the railway track which is used to fill under slab panel space so as to provide a stabilized track support and a tool for reduction of noise and vibration. To increase the workability of grouting, this study investigates the effect of temperature on cement-asphalt mortar by analyzing its physical and mechanical properties before/after hardening according to the temperature (10, 15, 20, 25, $30^{\circ}C$). According to the test results, it is found that as for the physical property of fresh cement-asphalt mortar the more mixture temperature become higher or lower, the more fluidity become worse. But by increasing reducing agent amount and its unit quantity, the required fluidity is met. The compressive strength as physical property of hardened cement-asphalt mortar become lower when temperature is lower but taking it by and large the physical properties of cement-asphalt mortar before/after hardening aren't so affected by temperature and well satisfy the requirement. And it has proved that rate of expansion and freezing and thawing resistance aren't affected by temperature.

• Journal of Sensor Science and Technology
• /
• v.27 no.4
• /
• pp.209-215
• /
• 2018

Recent research in animal behavior has shown that gradient information plays an important role in finding food and home. It is also important in optimization of performance because it indicates how the inputs should be adjusted for maximization/minimization of a performance index. We introduce perturbation as an additional input to obtain gradient information. Unlike the typical approach of calculating the gradient from the derivative, the proposed processing is very robust to noise since it is performed as a summation. Experimental results prove the validity of the process of spatial gradient acquisition. Quantitative indices for measuring the effect of the amplitude and the frequency are developed based on linear regression analysis. Drones are very useful for environmental monitoring and an autonomous path planning is required for unstructured environment. Guiding the drone for finding the origin of the interested physical property is done by estimating the gradient of the sensed value and generating the drone trajectories in the direction which maximizes the sensed value. Simulation results show that the proposed method can be successfully applied to identify the source of the physical quantity of interest by utilizing it for path planning of an autonomous drone in 3D environment.

• The Journal of the Acoustical Society of Korea
• /
• v.19 no.1
• /
• pp.73-77
• /
• 2000

It is necessary to express and evaluate annoyances, caused by noises, as a comparable quantity for establishing an efficient, economic and user-oriented noise control plan. In particular, cares should be taken for impact noises, since their dynamic properties are different from those of steady-state noises. A series of preliminary experiments were carried out to quantify the annoyances caused by floor impact noises. Results suggests that the characteristics of an impact source was more important factor than the properties of a floor structure for determining loudness and noisiness of subjects. Also, the heavy impact source was found to be felt louder and noisier by 5-6dB than the light impact source.