• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2009.10a
• /
• pp.755-761
• /
• 2009

The major advantage of transparent materials over traditional materials in noise barriers is aesthetics. The transparent panel materials such as clear plastic or glass are an ideal way of reducing or virtually eliminating the visual impact of a noise barrier. With the use of transparent materials, the drivers' view of the roadside and the sunlight penetration to the highway would not be blocked. With the use of transparent materials, the highway and barrier appear less imposing. Korean Industrial Standards for soundproof panels have been established. But, transparent soundproof panels are not included in this standards. And, some specifications provide only a few basic characteristics for transparent soundproof panels. To develop guidelines on quality criteria for transparent soundproof panel, their mechanical properties such as wind load resistance, safety under impact, and abrasion resistance were experimentally investigated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.1242-1248
• /
• 2001

In this paper, the process of development of resilient sleepers, which improves the train safety, passenger comport and reduces the noise and vibration, is presented. To determine the required material properties of elastic pad, static and dynamic simulations are performed and is applied in manufacturing. Lateral resistance and durability characteristics of the resilient sleepers are experimentally investigated. From the experiment results, it is investigated that the displacement is less for sleeper with elastic pad than that in ordinary PC form. However, the lateral resistance is investigated little less -for sleeper with elastic pad than ordinary PC form. These results indicate that the elastic pad can reduce possibility of rail-corrugations and thus resulting in the reduction of maintenance costs.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.04a
• /
• pp.202-203
• /
• 2013

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.8
• /
• pp.756-762
• /
• 2012

A method of the low-frequency noise reduction in an enclosure by using an array of Helmholtz resonator is presented. An integral form of equation, which represents the acoustical coupling between the internal sound field and the resonator array, is formulated so that the boundary element method can be applied to solve the coupling problem. It is shown that the resonator array on the surface of the enclosure can be regarded as impedance patches on the boundary element. Experiments on a simple enclosure acoustically coupled with an array of resonators are conducted to verify the method. The predicted noise reduction by the boundary element method shows good agreement with the measured one. The effects of the resistance of resonators as well as the number of resonators on the noise reduction are demonstrated. As a practical example, the presented method is applied to the payload fairing of a space launcher with resonator arrays. It is demonstrated that the resistance of resonators affects significantly the required number of resonators to achieve a desired noise reduction.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.12 s.115
• /
• pp.1143-1149
• /
• 2006

The microstrip square open loop resonator has been employed to reduce the phase noise in VCO. The microstrip square open loop resonator has the large coupling coefficient value, which makes a high Q value, and has reduced the phase noise of VCO. To increase the tuning range of VCO, varactor diode has been connected at the tunable negative resistance in VCO. The output power and harmonic characteristics of VCO has been obtained 4.83 dBm and -28.83 dBc, respectively. The phase noise of VCO has been $-112.33{\sim}-116.16dBc/Hz$ @ 100 kHz in the tuning range, $5.735{\sim}5.845GHz$.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.2
• /
• pp.205-213
• /
• 2011

The characteristics of noise generation in the suction nozzle of a vacuum cleaner are analyzed numerically and experimentally. First, the flow resistance induced by each element in the suction nozzle of a vacuum cleaner with a double-blade rotary fan is investigated numerically and its relation with flow-induced noise and suction performance is examined in an anechoic room. The flow resistance and vorticity in the suction nozzle are calculated, and it is found that they are closely related to flow-induced noise and that the upper limit of noise reduction is only 4 dBA. This upper limit can be achieved by changing the design of the brush nozzle. Two methods for noise reduction by enlargement of flow-inlet area and by optimization of the number of blades are tested. Finally, the effects of each method are verified experimentally.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.330-333
• /
• 2005

The paper presents a numerical solution to the problem of a hot rigid indenter siding over a thermoelastic Winkler foundation with a thermal contact resistance at constant speed. It is shown analytically that no steady-state solution can exist for sufficiently high temperature or sufficiently small normal load or speed regardless of the thermal contact resistance. However, the steady state solution may exist in the same situation if the thermal contact resistance is considered. This means that the effect of the large values of temperature difference and small value of force or velocity which occur at no steady state can be lessened due to the thermal contact resistance. When there is no steady-state the predicted transient behavior involves regions of transient stationary contact interspersed with regions of separation regardless of the thermal contact resistance. Initially, the system typically exhibits a small number of relatively large contact and separation regions, but after the initial transient the trailing edge of the contact area is only established and the leading edge loses contact, reducing the total extent of contact considerably. As time progresses, larger and larger number of small contact areas are established, until eventually the accuracy of the algorithm is limited by the discretization used.

• Journal of the Korean Data and Information Science Society
• /
• v.11 no.2
• /
• pp.157-172
• /
• 2000

Metal containers represent a situation where a specific metal is exposed to a wide variety of electrolytes of varying degrees of corrosivity. For example, hundreds, if not thousands of different products are packaged in an aluminum beverage can. These products vary in pH, chloride concentration and other natural or artificial ingredients which can effect the type and severity of potential corrosion. Both localized (perforation) and uniform corrosion (metal dissolution without the onset of pitting) may occur in the can. A quick test or series of tests which could predict the propensity towards both types of corrosion would be useful to the manufacturer. Electrochemical noise data is used to detect the onset and continuation of pitting corrosion. Specific noise parameters such as the noise resistance (the potential noise divided by the current noise) have been used to both detect pitting corrosion and also to estimate the pitting severity. The utility of noise resistance and other electrochemical parameters has been explored through the application of artificial neural networks. The versatility of artificial neural networks is further demonstrated by combing electrochemical data with electrolyte properties such as pH and chloride concentration to predict both the severity of both localized and uniform corrosion.

• Journal of the Institute of Convergence Signal Processing
• /
• v.13 no.1
• /
• pp.44-49
• /
• 2012

The indirect-contact ECG measurement is a newly developed method for unconstrained and nonconscious measurement in daily Life. This study is the first step to reducing the large background noise appearing in indirect-contact ECG. This study built the thermal noise model of capacitively coupled active electrode which is used in indirect-contact ECG. The results show that the level of thermal noise estimated by the thermal noise model is much the same as that of actual background noise for the capacitively coupled active electrode alone. By applying the actual electrical properties of a sample cotton cloth to the thermal noise model, the theoretical level of thermal noise in the indirect-contact ECG was estimated. The results also show that the level of op-amp's intrinsic noise is so small that it can be negligible in comparison with thermal noise of resistors. The relationship between the level of thermal noise and the resistance of the bias resistor was derived, and it is the base for the further study how to choice the optimal resistance for the bias resistor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.267-272
• /
• 2014

In this paper, we analyze the characteristics for the driving shock resistance of the military vehicle through the bump test. Prior to the experiment, theoretical analysis was performed by using the SRS(shock response spectrum) and VRS(vibration response spectrum) analysis method. And we estimated the characteristics for the driving shock resistance of the military vehicle. Bump test was performed using the acceleration sensor and the driving test at a different speed. We evaluated the characteristics for the driving shock resistance of the military vehicle based on the result. And predicted values were compared with the theoretical analysis. In addition, we evaluated the results of the theoretical prediction of the SRS and the VRS analysis. And we evaluate the suitability of the prediction method at military vehicle shock analysis.