The Experts below are selected from a list of 78855 Experts worldwide ranked by ideXlab platform

Hae Kyun Cheong - One of the best experts on this subject based on the ideXlab platform.

  • hydraulic circuit for heavy equipment
    2008
    Co-Authors: Hae Kyun Cheong
    Abstract:

    A hydraulic circuit for heavy equipment is disclosed, which utilizes a hydraulic fluid supplied from a hydraulic pump for driving a cooling fan, as a pilot Signal Pressure, without installing a separate constant displacement pilot pump for supplying the pilot Signal Pressure to a control valve for controlling the hydraulic fluid to be supplied to a working device such as a boom. The hydraulic circuit includes first to third hydraulic pumps connected to an engine; a first control valve installed in a flow path of the first hydraulic pump; a second control valve installed in a flow path of the second hydraulic pump; a hydraulic motor connected to the third hydraulic pump; a cooling fan, connected to the hydraulic motor, for discharging cooling wind to an oil cooler; a temperature sensor for detecting a temperature of the hydraulic fluid in the hydraulic tank; an electric relief valve, installed in a drain flow path of the third hydraulic pump, for variably controlling a rotation velocity of the cooling fan; a controller for controlling the hydraulic Pressure that drives the hydraulic motor; and a pilot Pressure generator, installed in a pilot flow path branched and connected to a flow path of the third hydraulic pump, for supplying a pilot Signal Pressure to the first and second control valves when shifting.

Man Suk Jeon - One of the best experts on this subject based on the ideXlab platform.

  • hydraulic control valve for heavy equipment
    2008
    Co-Authors: Man Suk Jeon
    Abstract:

    A hydraulic control valve for heavy equipment is provided, which includes a valve body having a supply passage supplied with a hydraulic fluid from a hydraulic pump, ports for supplying the hydraulic fluid to an actuator or receiving the hydraulic fluid from the actuator, tank passages for returning the hydraulic fluid from the actuator to a hydraulic tank, and a first regeneration passage for supplying a part of the returned hydraulic fluid to the supply passage; a spool slidably installed in the valve body in accordance with supply of a pilot Signal Pressure from an exterior, and controlling flow of the hydraulic fluid supplied to the actuator from the supply passage during shifting; and a regeneration valve installed between the first regeneration passage and the tank passage, and including a piston moved by the hydraulic fluid from the hydraulic pump, a regeneration spool shifted by Pressure fluctuation of the supply passage to variably adjust a flow rate of the hydraulic fluid discharged from the first regeneration passage to the tank passage via a return passage, a first resilient member for resiliently supporting the regeneration spool in a direction opposite to a shifted direction of the regeneration spool, and a pilot piston for resiliently supporting a set Pressure of the first resilient member.

Taghi Golmohammadi - One of the best experts on this subject based on the ideXlab platform.

  • modeling Signal to noise ratio of otoacoustic emissions in workers exposed to different industrial noise levels
    Noise & Health, 2016
    Co-Authors: Parvin Nassiri, Mohammad Reza Monazzam, Kamal Azam, Sajad Zare, Akram Pourbakht, Taghi Golmohammadi
    Abstract:

    Introduction: Noise is considered as the most common cause of harmful physical effects in the workplace. A sound that is generated from within the inner ear is known as an otoacoustic emission (OAE). Distortion-product otoacoustic emissions (DPOAEs) assess evoked emission and hearing capacity. The aim of this study was to assess the Signal-to-noise ratio in different frequencies and at different times of the shift work in workers exposed to various levels of noise. It was also aimed to provide a statistical model for Signal-to-noise ratio (SNR) of OAEs in different frequencies based on the two variables of sound Pressure level (SPL) and exposure time. Materials and Methods: This case–control study was conducted on 45 workers during autumn 2014. The workers were divided into three groups based on the level of noise exposure. The SNR was measured in frequencies of 1000, 2000, 3000, 4000, and 6000 Hz in both ears, and in three different time intervals during the shift work. According to the inclusion criterion, SNR of 6 dB or greater was included in the study. The analysis was performed using repeated measurements of analysis of variance, spearman correlation coefficient, and paired samples t-test. Results: The results showed that there was no statistically significant difference between the three exposed groups in terms of the mean values of SNR (P > 0.05). Only in Signal Pressure levels of 88 dBA with an interval time of 10:30–11:00 AM, there was a statistically significant difference between the right and left ears with the mean SNR values of 3000 frequency (P = 0.038). The SPL had a significant effect on the SNR in both the right and left ears (P = 0.023, P = 0.041). The effect of the duration of measurement on the SNR was statistically significant in both the right and left ears (P = 0.027, P < 0.001). Conclusion: The findings of this study demonstrated that after noise exposure during the shift, SNR of OAEs reduced from the beginning to the end of the shift.

Parvin Nassiri - One of the best experts on this subject based on the ideXlab platform.

  • modeling Signal to noise ratio of otoacoustic emissions in workers exposed to different industrial noise levels
    Noise & Health, 2016
    Co-Authors: Parvin Nassiri, Mohammad Reza Monazzam, Kamal Azam, Sajad Zare, Akram Pourbakht, Taghi Golmohammadi
    Abstract:

    Introduction: Noise is considered as the most common cause of harmful physical effects in the workplace. A sound that is generated from within the inner ear is known as an otoacoustic emission (OAE). Distortion-product otoacoustic emissions (DPOAEs) assess evoked emission and hearing capacity. The aim of this study was to assess the Signal-to-noise ratio in different frequencies and at different times of the shift work in workers exposed to various levels of noise. It was also aimed to provide a statistical model for Signal-to-noise ratio (SNR) of OAEs in different frequencies based on the two variables of sound Pressure level (SPL) and exposure time. Materials and Methods: This case–control study was conducted on 45 workers during autumn 2014. The workers were divided into three groups based on the level of noise exposure. The SNR was measured in frequencies of 1000, 2000, 3000, 4000, and 6000 Hz in both ears, and in three different time intervals during the shift work. According to the inclusion criterion, SNR of 6 dB or greater was included in the study. The analysis was performed using repeated measurements of analysis of variance, spearman correlation coefficient, and paired samples t-test. Results: The results showed that there was no statistically significant difference between the three exposed groups in terms of the mean values of SNR (P > 0.05). Only in Signal Pressure levels of 88 dBA with an interval time of 10:30–11:00 AM, there was a statistically significant difference between the right and left ears with the mean SNR values of 3000 frequency (P = 0.038). The SPL had a significant effect on the SNR in both the right and left ears (P = 0.023, P = 0.041). The effect of the duration of measurement on the SNR was statistically significant in both the right and left ears (P = 0.027, P < 0.001). Conclusion: The findings of this study demonstrated that after noise exposure during the shift, SNR of OAEs reduced from the beginning to the end of the shift.

Mohammad Reza Monazzam - One of the best experts on this subject based on the ideXlab platform.

  • modeling Signal to noise ratio of otoacoustic emissions in workers exposed to different industrial noise levels
    Noise & Health, 2016
    Co-Authors: Parvin Nassiri, Mohammad Reza Monazzam, Kamal Azam, Sajad Zare, Akram Pourbakht, Taghi Golmohammadi
    Abstract:

    Introduction: Noise is considered as the most common cause of harmful physical effects in the workplace. A sound that is generated from within the inner ear is known as an otoacoustic emission (OAE). Distortion-product otoacoustic emissions (DPOAEs) assess evoked emission and hearing capacity. The aim of this study was to assess the Signal-to-noise ratio in different frequencies and at different times of the shift work in workers exposed to various levels of noise. It was also aimed to provide a statistical model for Signal-to-noise ratio (SNR) of OAEs in different frequencies based on the two variables of sound Pressure level (SPL) and exposure time. Materials and Methods: This case–control study was conducted on 45 workers during autumn 2014. The workers were divided into three groups based on the level of noise exposure. The SNR was measured in frequencies of 1000, 2000, 3000, 4000, and 6000 Hz in both ears, and in three different time intervals during the shift work. According to the inclusion criterion, SNR of 6 dB or greater was included in the study. The analysis was performed using repeated measurements of analysis of variance, spearman correlation coefficient, and paired samples t-test. Results: The results showed that there was no statistically significant difference between the three exposed groups in terms of the mean values of SNR (P > 0.05). Only in Signal Pressure levels of 88 dBA with an interval time of 10:30–11:00 AM, there was a statistically significant difference between the right and left ears with the mean SNR values of 3000 frequency (P = 0.038). The SPL had a significant effect on the SNR in both the right and left ears (P = 0.023, P = 0.041). The effect of the duration of measurement on the SNR was statistically significant in both the right and left ears (P = 0.027, P < 0.001). Conclusion: The findings of this study demonstrated that after noise exposure during the shift, SNR of OAEs reduced from the beginning to the end of the shift.