• Journal of rehabilitation welfare engineering & assistive technology
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• v.5 no.1
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• pp.41-46
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• 2011

A sensorineural hearing loss(SNHL) occurs when the cochlea in the inner has functional problem. The region in the cochlea with no(or very few) functioning inner hair cells or neurons called 'dead regions'. Amplification using hearing aid over a frequency range corresponding to a dead region may not a beneficial. In this paper, we compared speech recognition with different location of dead region and gain and searched effective gain for hearing aid with dead region. In order to experiment, eight people who has normal hearing ware tested, and we used white noise and babble noise(SNR=0 dB). we divided by three conditions, low, mid and high frequency dead region. In addition, the gains in dead region ware 14.5 dB, 11.5dB and 6 dB gain. There ware different results by location of dead region. The result of WRS and preference in mid-frequency dead region and high-frequency dead region ware higher than them in low-frequency dead region. When we compared as gains, the score of WRS with lower gain was higher than 14.5 dB gain, and the preference was lower as higher gain.

• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.485-491
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• 2002

The gyroscopes have been used as a suitable inertial instrument for the navigation guidance and attitude controls. The accuracy as very sensitive sensor is limited by the lock-in region (dead band) by the frequency coupling between two counter-propagating waves at low rotation rates. This frequency coupling gives no phase difference and an angular increment is not detected. This problem can be overcome by the mechanical dithering. The purpose of the mechanical dithering is to suppress the dead band, oscillate the monoblock about the rotation axis and add an external rotation rate. This paper presents the theoretical considerations of the mechanical performances of dither on the basis of the loading condition and angular characteristics due to the piezoelement deformation and the validity of theoretical equations are compared through FEM (Finite Element Method) simulations.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1661-1668
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• 2016

A fixed off-time controlled high power factor ac-dc LED driver is proposed in this paper, which employs a novel zero-crossing-compensation (ZCC) circuit based on a fixed off-time controlled scheme. Due to the parasitic parameters of the system, the practical waveforms have a dead region. By detecting the zero-crossing boundary, the proposed ZCC circuit compensates the control signal VCOMP within the dead region, and is invalid above this region. With further optimization of the parameters KR and Kτ of the ZCC circuit, the dead zone can be eliminated and lower THD is achieved. Finally, the chip is implemented in HHNEC 0.5μm 5V/40V HVCMOS process, and a prototype circuit, delivering 7~12W of power to several 3-W LED loads, is tested under AC input voltage ranging from 85V to 265V. The test results indicate that the average total harmonic distortion (THD) of the entire system is approximately 10%, with a minimum of 5.5%, and that the power factor is above 0.955, with a maximum of 0.999.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.2
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• pp.177-185
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• 2007

Hydraulic efficiency($T_{10}/T$) in clearwell is often estimated by L/W ratio. However, this estimation is not accurate because other factors which give an effect on hydraulic efficiency such as shape of basin, diffuser wall and intra-basin is ignored. Therefore, in this research, hydraulic efficiency is predicted by the quantitative analysis of dead zone using CFD simulation in a pilot scale clearwell. The results show that the reason why higher L/W ratio increase the hydraulic efficiency is to decrease the dead zone of linear region which is located between baffles. Diffuser wall or intra-basin also affects on hydraulic efficiency with this process. Also, we conclude that hydraulic efficiency can not be reached to 0.8 or higher.

• Journal of Power Electronics
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• v.16 no.1
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• pp.1-8
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• 2016

Dead time is typically incorporated in voltage source inverter systems to prevent short circuit cases. However, dead time causes an error between the output voltage and reference voltage. Hence, voltage equation-based algorithms, such as motor parameter estimation and back electromotive force (EMF)-based sensorless algorithms, are prone to estimation errors. Several dead-time compensation methods have been developed to reduce output voltage errors. However, voltage errors are still common in zero current crossing areas, and an effect of the error is much worse in a low speed region. Therefore, employing voltage equation-based algorithms in low speed regions is difficult. This study analyzes the conventional dead-time compensation method and output voltage errors in low speed operation areas. A current shaping method that can reduce output voltage errors is also proposed. Experimental results prove that the proposed method reduces voltage errors and improves the accuracy of the parameter estimation method and the performance of the back EMF-based sensorless algorithm.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.698-700
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• 1993

This paper describes characteristic analysis of VVVf type high-frequency considering dead time. Static power conversion are now used in a great variety of application including induction heating, high-frequency generation, DC/DC power converter, etc. In the circuit analysis, an offer circuit was compared with safety operating region and steady state characteristics considering dead time.

• The Journal of Internal Korean Medicine
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• v.25 no.4
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• pp.227-241
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• 2004

Objective : This study was performed to investigate neuroprotective effects of Bupleuri Radix against oxidative and ischemic damages. Method : To observe the neuroprotective effects against ischemic damage, ischemic insult was induced by oxygen/glucose deprivation (OGD) on organotypic hippocampal slice cultures (OHSC) from 1 week-old Sprague-Dawley rats. Propidium iodide (PI) fluorescence-stained neuronal dead-cell areas, area percentages and TUNEL-positive apoptotic cells in CA1 and dentate gyrus, and LDH levels in culture media of the OHSC were measured following Bupleuri Radix extract treatment. Result : The following results were obtained: (1) The $5\;{\mu}g/ml$ of Bupleuri Radix treatment demonstrated a significant decrease in PI fluorescence-stained neuronal dead-cell areas and area percentage in CA1 region of the OHSC from 18 hrs to 48 hrs following the OGD. The $50\;{\mu}g/ml$ of Bupleuri Radix treatment was also significant from 6 hrs to 48 hrs following the OGD and was more effective. (2) The 5 and $50\;{\mu}g/ml$ of Bupleuri Radix treatment demonstrated a significant decrease in PI fluorescence-stained neuronal dead-cell areas and area percentage in DG region of the OHSC from 6 hrs to 48 hrs following the OGD. The $50\;{\mu}g/ml$ treatment was more effective than the $5\;{\mu}g/ml$ treatment. (3) Bupleuri Radix treatment demonstrated a significant decrease in TUNEL-positive apoptotic cells in CA1 region (with 5 and $50\;{\mu}g/ml$) and in DG region (with $50\;{\mu}g/ml$) of the OHSC damaged by the OGD. (4) Bupleuri Radix treatment demonstrated a significant decrease in LDH concentrations in culture media of the OHSC damaged by the OGD. Conclusion : These results suggest that Bupleuri Radix has neuroprotective and control effects on inflammatory and immune responses where there has been ischemic damage to the central nervous system.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.40-44
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• 2013

This paper presents a design and characteristics analysis of novel 2-phase 4/3 switched reluctance motor (SRM) with short flux path for an air-blower application. The desired air-blower is unidirectional application, and requires a wide positive torque region without torque dead-zone. In order to get a wide positive torque region without torque dead-zone during phase commutation, asymmetric inductance characteristic with non-uniform air-gap is considered. The proposed motor could be started at any rotor position with high efficiency drive. The proposed 2-phase 4/3 SRM is verified by finite element method analysis.

• Journal of Korea Multimedia Society
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• v.17 no.4
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• pp.458-465
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• 2014

In this paper, we propose a strategy to distribute the energy consumption over the network. The proposed strategy is based on geographic routing. We use a smart base station that maintains the residual energy and location information of sensor nodes and selects a head node and an anchor node using this information. A head node gathers and aggregates data from the sensor nodes in a target region that interests the user. An anchor node then transmits the data that was forwarded from the head node back to the smart base station. The smart base station extends network lifetime by selecting an optimal head node and an optimal anchor node. We simulate the proposed protocol and compare it with the LEACH protocol in terms of energy consumption, the number of dead nodes, and a distribution map of dead node locations.

• The KIPS Transactions:PartA
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• v.17A no.2
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• pp.53-62
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• 2010

Mobile Sensor Vehicles, nodes of Mobile Sensor Network, are navigating for a specific, maybe unknown, region. For the precise usage of MSN, MSV has to be able to do localization by integrating information through communication by each other. In addition, MSV should be localized with various sensors equipped. In this research, we propose a set of techniques that improve accuracy using human mimic by combining and exploiting the existing techniques such as Dead-Reckoning, Computer Vision and Received Signal Strength Identification.