• Journal of Biomedical Engineering Research
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• v.30 no.1
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• pp.94-102
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• 2009

In this paper, we propose a hearing impairment simulator considering reduced frequency selectivity of the hearing impaired, and verify it's performance through experiments. The reduced frequency selectivity was embodied by spectral smearing using linear prediction coding(LPC). The experiments are composed of 4 kinds of tests; pure tone test, speech reception threshold(SRT) test, and word recognition score(WRS) test without spectral smearing and with spectral smearing. The experiments of the hearing impairment simulator were performed with 9 subjects who have normal hearing. The amount of spectral smearing was controlled by LPC order. The percentile score of WRS test without smearing is $89.78{\pm}2.420%$. The scores of WRS with 24th LPC order and with 8th LPC order are $88.00{\pm}3.556%$ and $83.78{\pm}2.123%$ respectively. It is verified that WRS score is lowered by decreasing LPC order. This is a reasonable result considering that spectral smearing is getting heavier according to decreasing LPC order. It is confirmed that spectral smearing using LPC simulates the reduced frequency selectivity of the hearing impaired and affects the clearness of speech reception.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1664-1675
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• 2021

In order to verify the statistical performance of the nonparametric tests used in the MARSSIM approach, all plausible contamination distribution types that can be encountered in a survey area should be investigated. As the first of such investigations, this study aims to perform the verification for normal distribution of the contamination in a survey area by simulating the collection of random samples from it through the Monte Carlo simulation. The results of the simulations conducted for a total of 81 simulation cases showed that Sign test and WRS test both exhibited an excellent statistical performance: 100% for the former and 98.8% for the latter. Therefore, in final status surveys of the MARSSIM approach, a high statistical performance can be expected in applying the nonparametric hypothesis tests to survey areas whose net contamination can be assumed to be normally distributed.

• Korean Journal of Occupational Health Nursing
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• v.26 no.4
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• pp.207-217
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• 2017

Purpose: This study aimed to evaluate the workplace response system (WRS) against infectious disasters (IDs) based on the response attitudes and capacity of occupational health nurses (OHNs) who worked during the 2015 Middle East Respiratory Syndrome (MERS) outbreak in South Korea. Methods: Fifty-one participants who had worked as OHNs at the time of the 2015 MERS outbreak were surveyed from November 20 to December 10, 2016. Data were collected using a self-report questionnaire and analyzed using descriptive statistics and McNemaer's test. Results: According to the survey results, the following were lacking in the WRS: a dedicated ID-response team, manuals, related education programs for OHNs, and health education programs for workers. Results also confirmed that workers were vulnerable to new infectious diseases because of the lack of health checkups and support for workers before and after business trips abroad. Among the respondents, 98.0% answered affirmatively that an ID was important for health management in the workplace, but 64.7% answered that it was difficult to manage an ID. The perceived capacity items to respond to IDs ranged from 3.0 points to 3.3 points. This scores were generally high. Conclusion: As the WRS is currently insufficient, it is necessary to develop an adequate WRS to IDs by addressing the identified problems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.831-840
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• 2010

In this paper, we propose a hearing impairment simulator considering reduced frequency selectivity and asymmetrical auditory filter of the hearing impaired, and we verified the reduced frequency selectivity and asymmetrical auditory filter affected in speech perception through experiments. The reduced frequency selectivity has made embodied by spectral smearing using LPC(linear prediction coding). The shapes of auditory filter are asymmetrical different with each center frequency. Hearing impaired person which has hearing loss was differently changed with that of normal hearing people and it has different value for speech of quality through auditory filter. The experiments confirmed subjective test and objective test. The subjective experiments are composed of 4 kinds of tests: pure tone test, SRT(speech reception threshold) test, and WRS(word recognition score) test without spectral smearing, and WRS test with spectral smearing. The experiment of the hearing impairment simulator was performed from 9 subjects who have normal ears. The amount of spectral smearing was controlled by LPC order. The asymmetrical auditory filter of proposed hearing impairment simulator was simulated and then some tests to estimate the filter's performance objectively were performed. The objective experiment as simulated auditory filter's performance evaluation method used PESQ(perceptual evaluation of speech quality) and LLR(log likelihood ratio) for speech through auditory filter. The processed speech was evaluated objective speech quality and distortion using PESQ and LLR value. When hearing loss processed, PESQ and LLR value have big difference according to asymmetrical auditory filter in hearing impairment simulator.

• International Journal of Aeronautical and Space Sciences
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• v.6 no.1
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• pp.44-51
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• 2005

To provide more accurate and reliable positioning and timing services to Korean nationwide users, the Ministry of Maritime Affairs and Fisheries of Korea is implementing Korean NDGPS (Nationwide DGPS), which is operational partly. And it also has a plan to construct WADGPS (Wide Area Differential GPS) system using sites and equipments of the NDGPS reference stations. For that, Seoul National University GNSS Laboratory is implementing and testing prototypes of WRS (Wide-area Reference Station) and WMS (Wide-area Master Station). Until now, because there are not enough installed WRSs to be used for computing wide area correction information, we cannot test algorithms of WMS with the data processed actually in WRSs. Therefore to evaluate the performance of the algorithms, we made a MATLAB program which can process RINEX (Receiver INdependent Exchange) format data with WADGPS algorithm. Using that program which consists of WRS, WMS and USER modules, we processed the data collected at NDGPS reference stations, which are saved in RINEX format. In WRS module, we eliminate the atmospheric delay error from the pseudorange measurement, smooth the measurement by hatch filter and calculate pseudorange corrections for each satellite. WMS module collects the processed data from each reference stations to generate the wide area correction information including estimated satellite ephemeris errors, ionospheric delays at each grid point, UDRE (User Differential Range Error), GIVE (Grid Ionosphere Vertical Error) and so on. In USER part, we use the measurements of reference stations as those of users and estimate the corrected users' positions and protection levels (HPL, VPL). With the results of estimation, we analyzed the performance of the algorithms. We assured the estimated UDRE /GIVE values and the protection levels bound the corresponding errors effectively. In this research, we can expect the possible performance of WADGPS in Korea, and the developed modules will be useful to implementation and improvement of the algorithms.

• 재활복지
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• v.18 no.4
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• pp.295-314
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• 2014

The purpose of this study was to supply the baseline data for auditory rehabilitation in the field through error type and rate of the phoneme which the hearing impaired feel difficulty to discriminate. Thirty participants with sensorineural hearing loss heard KCPT lists through recorded voice by male and female to get the data about error type and KCPT score accordance with talker's gender. In the initial consonant test list, /ㄷ/, /ㅂ/, /ㅃ/, /ㅉ/, /ㅌ/ showed more than 30% error rate while /ㄱ/and /ㄷ/ showed in final consonant test list. The most common error type was the initial consonant substitution or the final consonant substitution for the initial or final consonant test lists. Talker's gender effect was not signigicant showing no statistical difference between the scores when compared results from male voice and female voice. It means that KCPT can be used regardless of talker's gender in clinics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.430-440
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• 2021

The purpose of this study was to analyze the degree of depression, cognitive function, communication ability, and the quantitative electroencephalogram (EEG) in elderly individuals with hearing loss and to investigate their inter-relationship. Hearing-impaired elderly participants, aged 60 years or older (37 men and 26 women) who visited the S Hearing Rehabilitation Center in Y City from June 20, 2020, to September 3, 2020, participated voluntarily after a recruitment announcement.The participants' overall characteristics, depression, and cognitive functions were evaluated with a structured questionnaire. The Word Recognition Score (WRS) was evaluated with an audiometer using the Korean Standard Monosyllabic Word Lists for Adults (KS-MWL-A). The quantitative EEG was measured with dry electrodes using a 2-channel EEG on the frontal lobes Fp1 and Fp2. The results are summarized as follows: Communication ability showed a positive correlation with the left-right symmetry of the frontal lobes (**p<.01) and a negative correlation with right-brain mental distraction and stress (*p<.05). In the difference WRS test for each group, the left-right symmetry of the frontal lobes (**p<.01) showed the greatest correlation with communication ability. Our results suggest that the left-right symmetry of the frontal lobes can be a biomarker indicative of the communication ability of older people with hearing impairments.

• Journal of Korean Medicine Rehabilitation
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• v.28 no.2
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• pp.47-60
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• 2018

Objectives The objective of this study was to investigate the effect of Anti-condensing on the composition of ChondroT Methods Specimens are divided in 7 groups (Control, ChondroT, Lonicerae Folium (Gumenhwa, GEH), Angelicae Gigantis Radix(Danggui, DG), Phellodendri Cortex(HwangBaek, HB), Osterici Radix(Kanghwal, KH), Clematidis Radix(Weeryungsun, WRS)) Each specimen is subjected to a concentration of 20 %, 10 %, and 5 %, and is administered to collagen and thrombin-stimulated platelets. Results In the anticoagulance effect test, Lonicerae Folium and ChondroT very well. The effect was high in order of Lonicerae Folium-Angelicae Gigantis-Phellodendri Cortex-Osterici Radix and Clematidis Radix. Conclusions ChondroT has anti-condensing effects on blood platelet.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.5
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• pp.13-20
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• 2008

Although digital hearing aid algorithms have been developed to compensate hearing loss and to help hearing impaired people to communicate with others, digital hearing aid user still complain about difficulty of hearing the speech. The reason could be the quality of speech through digital hearing aid is insufficient to understand the speech caused by feedback, residual noise and etc. And another thing is masking effect among formants that makes sound quality low. In this study, we measured the masking characteristics of normal listeners and hearing impaired listeners having presbyacusis to confirm masking effect in speech itself. The experiment is composed of 5 tests; pure tone test, speech reception threshold (SRT) test, word recognition score (WRS) test, puretone masking test and speech masking test. In speech masking test, there are 25 speeches in each speech set. And log likelihood ratio (LLR) is introduced to evaluate the distortion of each speech objectively. As a result, the speech perception became lower by increasing the quantity of formant enhancement. And each enhanced speech in a speech set has statistically similar LLR, however speech perception is not. It means that acoustic masking effect rather than distortion influences speech perception. In actuality, according to the result of frequency analysis of the speech that people can not answer correctly, level difference between first formant and second formant is about 35dB, and it is similar to result of pure tone masking test(normal hearing subject:36.36dB, hearing impaired subject:32.86dB). Characteristics of masking effect is not similar between normal listeners and hearing impaired listeners. So it is required to check the characteristics of masking effect before wearing a hearing aid and to apply this characteristics to fitting.