• Journal of Clinical Otolaryngology Head and Neck Surgery
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• v.29 no.2
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• pp.235-239
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• 2018

Due to the structure with one end closed, the external ear resonance effect in which the high frequency is amplified can be generated, and the sound can be perceived well. The external ear resonance normally has a first peak and a second peak. On average, the first peak has a gain of 18.6 dB at 2620 Hz and the second peak has a gain of 18.2 dB at 4210 Hz. The resonance of the external auditory canal changes with the state of the tympanic membrane, the presence of the ventilation tube, and the structure (length, diameter, shape) of the external auditory canal. A patient with a postauricular meatomastoid cutaneous fistula was admitted to the hospital with a foreign body which is the molding of the hearing aid. After removal of the foreign body, the resonance of the external auditory canal was lost and the subjective sound cognitive ability decreased. In the case of postauricular meatomastoid cutaneous fistula, we confirmed the improvement of sound cognitive ability, the change of pure tone hearing threshold, and the change of the external ear resonance after reconstruction of the ear canal without middle ear reconstruction.

• Korean Journal of Occupational Health Nursing
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• v.3
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• pp.5-20
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• 1993

This study was aimed to investigate the actual condition of the performance of the occupational health nursing services, and to analyze a main cause which affects on the execution of its duties for occupational health nurses in occupational group health service. It had been surveyed by responsed data from the 105 respondents out of 180 persons. The results were as follows : 1. In performance of occupational health nursing services by the number of assigned plant, participation rate of health examination tended to significantly increase with decreasing the number of assigned and it was observed that the visiting rate of every month was also significantly higher on touring inspection of work plant, recommendation of facility improvement for work environment, understanding the modification of manufacturing process, and inspection of welfare and sanitation facilities. 2. While they executed their nursing services according to duration of service, the more, their duration of service was, the higher, participation rate of health examination, health check in returning to work for injured workers, talk with other health managers on promoting welfare, service evaluation for a year plan, record of health statistic, and experience of first aid service were. And it was found out that the visiting rate of every month was also significantly higher on touring inspection of work plant. 3. In regard to occupational health nursing services by age, the participation rate of health examination and the experience of first aid service were significantly higher as the age increased. And also the visiting rate of every month was significantly higher on touring inspection of work plant, compared with young ones. 4. In performance of occupational health nursing services by the time required visiting plant, The shorter, the time required visiting plant was, the higher, the visiting rate of every month was, on time of health consultation for diseased workers, and inspection of welfare and sanitation facilities. 5. The subjects of health education were mostly liver disease and occupational hearing loss and video tape was used mostly in health education, monthly health education was the highest in 1-3 times(74.5%) and its duration was the highest in about 60 minutes(33.3%). 6. Vaccination of hepatitis among the specific health services was the highest accounting for 64.7%.

• Journal of the Korean Data and Information Science Society
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• v.25 no.4
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• pp.819-828
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• 2014

In this paper, we analyze the characteristics of the English vocalization of deaf students and present the basic data for the development of personalized English learning aid tools that reflect its features. We visited hearing special schools in Seoul and Daegu and recorded English vocalization of the deaf students in order to analyze the characteristics of deaf students' English vocalization. We analyzed the data by Praat program, an professional voice analysis program. The voice features of deaf students' English vocalization were extracted and then compared with those of non-deaf students' English vocalization.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.149-156
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• 2012

A digital input class-D audio amplifier is presented for digital hearing aid. The class-D audio amplifier is composed of digital and analog circuits. The analog circuit converts a digital input to a analog audio signal (DAC) with noise suppression in the audio band. An interpolated digital delta-sigma modulator is used to convert data types between digital signal processor (DSP) and digital-to-analog converter (DAC). An 16-bit, 25-kbps pulse code modulated (PCM) input is interpolated to 16-bit, 50-kbps by a digital filter. The output signal of interpolation filter is noise-shaped by a third-order digital sigma-delta modulator (SDM). As a result, 1.5-bit, 3.2-Mbps signal is applied to simple digital to analog converter.

• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.317-322
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• 2018

It has been generally known that a hole presenting on the center of pole piece for the loudspeaker can be very helpful for the heat, which is radiated by Joule Effect at the voice coil, to emit to the outside of the magnetic gap. The existence of hole can also become a cause of the changes of the acoustical properties about the loudspeaker. The resonance frequency of loudspeaker increased with the increase of hole radius. However, increasing the hole length resulted in the decrease of the resonance frequency. These results are in an excellent agreement with the theoretical predictions for the equivalent mechanical circuit of Bass-Reflex cabinet system. The acoustical property of the loudspeaker with hole can be also predicted by the theoretical interpretation of Bass-Reflex cabinet system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.936-941
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• 2004

In recent years, the rapid growth of portable electronic devices requires the high-energy density characteristics of batteries. Zinc air batteries have specific capacity as high as 820mAh/g. However, Zinc air batteries used for hearing aid applications only so far, because the atmosphere could affect it, and it has weakness in the rate capability. However, recent developments of electrode manufacturing technologies made us to overcome that weakness. And the efforts of applying zinc air batteries to portable electronic devices, especially in cellular phone application have been increased. In this paper, the effects of conducting material and polymer binder in cathode on the electrochemical characteristics were investigated. Our research team succeeded in producing 2.4Ah class zinc air battery for cellular phone application. Its volumetric energy density was 920 wh/l, and gravimetric energy density was 308 wh/kg. The volumetric energy density of our zinc air battery is two times higher than one of lithium secondary battery, and three times higher than that of alkaline manganese battery.

• Journal of Korean Clinical Nursing Research
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• v.17 no.3
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• pp.443-454
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• 2011

Purpose: The purpose of this study was to investigate the predictors of delirium in patients after orthopedic surgery. Methods: Participants were 121 orthopedic surgery patients from one university affiliated hospital located in Seoul. The instrument of Delirium Observation Screening Scale (DOS) developed by Schuurmans et al. (2003) was utilized. Data were collected from September 1st, 2010 to March 31st, 2011 and analyzed using SPSS 12.0 with descriptive statistics, t-test, chi-square test and logistic regression. Results: The delirium in patients after orthopedic surgery was occurred in 9 (7.4%) out of 121 patients. Several factors were associated with the delirium occurrence age, admission route, preadmission Activity of Daily Living (ADL), preadmission hearing aid use, preadmission walking degree, diagnosis, type of surgery, Intensive Care Unit (ICU) stay after surgery, restraint, drainage tube, time of admission to surgery, preoperative albumin and preoperative sodium. Preadmission ADL, preoperative sodium and time of admission to surgery were the significant predictors of the delirium occurrence. Conclusion: Study results may help nurses predicting and detecting delirium early and providing preventive measures to the patients with high risk of delirium after orthopedic surgery.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.43-51
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• 2013

This paper presents a design and implementation of a low power switched-capacitor 3rd-order delta-sigma modulator for a digital hearing-aid application. The power consumption is reduced by minimizing the output swing of integrators through optimizing the coefficients of modulator architecture and using class-AB output operational amplifiers. The modulator was implemented in a 130nm CMOS technology, and measured to have 79dB of SNR(Signal-to-Noise Ratio) in the signal bandwidth between 100Hz and 10kHz with an oversampling ratio of 160. The power consumption was $60{\mu}W$ from 1.2V power supply and the modulator core occupied $0.53mm{\times}0.53mm$.

• Journal of Biomedical Engineering Research
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• v.26 no.3
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• pp.139-144
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• 2005

An implantable microphone that can be utilized as part of a totally implantable hearing aid is designed and implemented. The proposed microphone is implanted in the center of the pinna, and designed to ensure the speech frequency range and the appropriate sensitivity. The characteristics of the proposed microphone are evaluated using a finite element analysis (FEA). The microphone is composed of a small electric condenser microphone, titanium case 6.2mm in diameter and 3mm high, and $10{\mu}m$ SUS316L vibrating membrane in contact with hypodermic tissue to maintain the sensitivity of the microphone. The microphone components are all made of biocompatible materials, then the assembled microphone is hermetically sealed using a polymer and ceramic. Experiments with the fabricated microphone confirm an operational bandwidth of up to 5kHz without any decline of sensitivity in 6mm of hypodermic tissue.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• v.61 no.12
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• pp.650-657
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• 2018

Background and Objectives The present study aimed to compare receptive and expressive language development in children who have undergone simultaneous bilateral cochlear implantation (SCI) and those who have undergone bimodal stimulation (unilateral CI+ hearing aid). Subjects and Method In a retrospective analysis of clinical data, 15 pediatric patients who have received SCI and nine patients who have received bimodal stimulation (BM group) were enrolled. CI was performed for all patients at 24 months of age. Category of Auditory Performance (CAP) scores, Infant-Toddler Meaningful Auditory Integration Scale (IT-MAIS) scores, and developmental quotients (DQ) for expressive and receptive language were compared between the groups at 12 month of follow-up. The Percentage of Consonants Correct (PCC) of children evaluated at 4 years old was also compared. Results At 12 months of follow-up, significantly greater improvements in CAP scores (${\Delta}4.25{\pm}0.5$) were noted in the SCI group compared to the BM group (${\Delta}3.56{\pm}0.88$, p=0.041). Significantly greater improvements in IT-MAIS scores were also noted in the SCI group (${\Delta}36.17{\pm}4.09$) than in the BM group (${\Delta}30.17{\pm}2.91$, p=0.004). The DQ of receptive language was higher in the SCI group than in the BM group ($87.6{\pm}15.4%$ vs. $75.5{\pm}12.0%$, p=0.023) at 12 months of follow-up. Moreover, early SCI was associated with better receptive language skills. PCC index of children at 4 years old was higher in the SCI group than in the BM group ($88.5{\pm}13.2%$ vs. $62{\pm}15.8%$, p=0.014). Earlier SCI was associated with even greater improvements. Conclusion Bilateral SCI is associated with significant improvements in language development when compared with bimodal stimulation. Earlier SCI was associated with better outcomes.