• The Journal of the Acoustical Society of Korea
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• v.36 no.1
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• pp.30-38
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• 2017

In this paper, we propose an underwater acoustic sensor fault detection method for passive sonar systems. In general, a passive sonar system displays processed results of array signals obtained from tens of the acoustic sensors as a two-dimensional image such as displays for broadband or narrowband analysis. Since detection result display in the operation software is to display the accumulated result through the array signal processing, it is difficult to determine the possibility where signal may be contaminated by the fault or failure of a single channel sensor. In this paper, accordingly, we propose a detection method based on the analysis of RMSCR (Root Mean Square Crossing-Rate), and the processing techniques for the faulty sensors are analyzed. In order to evaluate the performance of the proposed method, the precision of detecting fault sensors is measured by using signals acquired from real array being operated in several coastal areas. Besides, we compare performance of fault processing techniques. From the experiments, it is shown that the proposed method works well in underwater environments with high average RMS, and mute (set to zero) shows the best performance with regard to fault processing techniques.

• The Journal of the Acoustical Society of Korea
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• v.36 no.4
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• pp.254-260
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• 2017

The purpose of this study is to evaluate the sound absorption characteristics of a human body according to the amount of clothing worn by using reverberation method measurement method for developing standard test dummy, which can be used for testing absorption of occupied audience chair. Test method was based on the previous study (Conti et al., 2004), each experiment is conducted in the reverberation room and a subject wearing clothes is standing in that chamber. In this experiment, the sound absorption area of each frequency band according to the wearing of various material clothing was measured. As a result of measurements, the average sound absorption area of the whole frequency band was $0.25m^2-0.48m^2$ in case of a subject not wearing outer clothes, and $0.38m^2-0.98m^2$ in case of wearing of outerwear. Polyester tops by showing the maximum value, the highest characteristics in the 800 Hz to 1 kHz band among the rest of fiber materials. The outer jacket made of the wool and cotton materials show a higher absorption area as the frequency increases to the higher frequency band. The change of the sound absorption area according to the clothing amount was divided by the thermal resistance (clo) of the worn clothes and the weight per body surface area.

• The Journal of the Acoustical Society of Korea
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• v.37 no.3
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• pp.147-155
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• 2018

In this paper, we tried to find out sound quality metrics to express discomfort of overload excavator noise and to develop sound quality indexes through multiple regression analysis by using them. For this purpose, the interior noise of cabin under overload condition was recorded for six excavator models with different noise properties and Jury test was carried out by PCM (Paired Comparison Method) and MEM (Magnitude Estimation Method). Jury test result with low consistency was classified into two groups with different preference tendencies by cluster analysis and multiple regression analysis was conducted in order to find out which sound quality metrics have significant effects on discomfort(low preference). As a result, we figured out that the sound quality metrics to express the discomfort were the partial loudness (= $PN_{10Bark}$) between 0 and 10 Bark in case of group1 and the difference between engine noise(= $dB_{EG}$) and hydraulic system noise ($dB_1$) in case of group2. Using the results of preference ranking and tendency analysis of PCM followed by the correlation analysis between PCM and MEM, the more reliable results were adopted by excluding the data with low consistency obtained from Jury test via MEM.

• The Korean Journal of Emergency Medical Services
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• v.12 no.1
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• pp.27-41
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• 2008

Purpose : With increasing number of school accidents, it is crucial to find out necessity of first aid training among school health educator. This study has been conducted to have an clear idea on the demands and necessity for first aid training and what kind of training is most required from school health educator. Method : In this study, questionnaires from 87 school health educator in elementary, middle and high school health educator in the city D were analyzed. The survey was carned out from May 26, 2008 to June 7, 2008 and from the collected data, frequency, independent two samples t-test, paired T-test, one way ANOVA and pearson's correlation were conducted with SPSS 14.0. Result: 1. 51.61 % of nurse-teachers experienced emergency situations and the relations between the necessity they felt from experiencing those situations and demands for first aid training were not statistically meaningful(t=1.87, p= .175). 2. Necessity and demands for the first-aid training were checked with three point scale and there were statistical significance between the two with $2.44{\pm}.47$ and $2.24{\pm}.47$ respectively(t=3.275, p= .000). 3. 86.20%(75 persons) of the respondents have had received first aid training and the training they received were CPR 82.75%(72 persons), primary survey 81.60%(7l persons), contact to 911 79.30%(69 persons) and wounds treatment(lacerated wounds, bum and chilblains) 75.86%( 66 persons) in order. 4. As for the questions that ask on confidence of first-aid treatment, 80% answered they are confident on some limited kinds of treatments, 16% said they are confident and 4% answered they lack confidence. As for the treatment that they can show the highest confidence, wounds treatment topped the list with 93.24%, nose bleeding and removing foreign substance, and stanching followed the list with 82.43% and 81.08% respectively. 5. 97.67% of respondents said they were willing to take training and 89.62% answered to take the training to deal with emergency situations that are taking place in their schools. As for the question that asks for the most wanted treatments, CPR topped the list with 32.18%(28 persons) and treatment for obstruction of airway and shock followed the list with 35.63%(31 persons) and 27.59%(24 persons). Conclusion : Currently, first aid treatment has been centered on CPR, primary survey, contact to 119 and wounds treatment. However, since most of school health educator are fairly confident with wounds treatment, stanching and other first aids, in future training it will be more desirable to focus on CPR and treatment for obstruction of airway and shock that were shown to be most wanted by school health educator.

• Journal of dental hygiene science
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• v.12 no.6
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• pp.652-659
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• 2012

The purpose of this study was to examine whether senior simulation would bring any positive change to the attitude of dental hygiene students toward the elderly. The experimental group consisted of 58 dental hygiene students at a college. The experimental procedure was to do activities for 40 minutes wearing aging simulation suit. Self administered questionnaires were used to ask the attitude toward the elderly after senior simulation. The data were analyzed with SPSS program. General and aging related characteristics of subjects were analyzed through descriptive statistics. To testify the differences of the attitude after senior simulation, paired t-test was used. An experiment was conducted from May 27 to June 14, 2012, and the findings of the study were as follows: 1. There wasn't any perfect positive change in the overall attitude of the students toward elderly people after senior simulation, but their attitude got a little more positive whereas they took a neutral attitude in the past; 2. The students who had ever lived with elderly people under the same roof and who had ever received education related to the elderly underwent a more positive change in their attitude toward the elderly; 3. To what extent senior simulation was helpful for the understanding of the elderly was checked, and the majority replied that it was very useful or useful for the understanding of their physical aspects. The findings of the study confirmed that senior simulation didn't change the overall attitude of the students toward the elderly in a positive way yet brought about some positive changes in part. Therefore senior simulation is expected to be one of significant educational programs that could encourage students to have a better physical understanding of the elderly, to take a more positive attitude to them and to provide them with quality dental service.

• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.479-487
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• 2021

In this paper, we propose an Sound Event Detection (SED) model using self-training based on a noisy student model. The proposed SED model consists of two stages. In the first stage, a mean-teacher model based on an Residual Convolutional Recurrent Neural Network (RCRNN) is constructed to provide target labels regarding weakly labeled or unlabeled data. In the second stage, a self-training-based noisy student model is constructed by applying different noise types. That is, feature noises, such as time-frequency shift, mixup, SpecAugment, and dropout-based model noise are used here. In addition, a semi-supervised loss function is applied to train the noisy student model, which acts as label noise injection. The performance of the proposed SED model is evaluated on the validation set of the Detection and Classification of Acoustic Scenes and Events (DCASE) 2020 Challenge Task 4. The experiments show that the single model and ensemble model of the proposed SED based on the noisy student model improve F1-score by 4.6 % and 3.4 % compared to the top-ranked model in DCASE 2020 challenge Task 4, respectively.

• Journal of Korean Society on Water Environment
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• v.37 no.1
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• pp.32-46
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• 2021

South Korea has been divided into quantities and water quality, and due to a revision of the Government Organization law in June 2018, the controversial water management system was integrated into the Ministry of Environment. The total Maximum Daily Loads System has been called the flower of water quality control, and since 2004, all three major river systems which have been introduced into the Han River system, despite its various difficult environments, and subsequently leading to all of the four major rivers undergoing obligatory implementation since 2013. Currently, the target TMDL (Han River Phase 1 and Other Water Systems Phase 3) for the 2020 stage has been implemented. The domestic TMDL established a basic plan for calculating the load which complies with the unit watershed's target water quality, as well as an implementation plan for annual load management, both which have been institutionalized in order to evaluate load compliance on a repeated annual basis. Local governments ask external organizations to conduct investigations every year in order to assess the transition, which thereby requires tens of millions of won every year. Therefore, an assessment and management model that can be easily operated at the TMDL personnel level is required. In this study, when the Han river Water System TMDL was implemented in earnest, we confirmed the the water quality improvement effect when TMDL was introduced to major inflow tributaries (TancheonA, JungnangA, AnyangA) under the Seoul City's jurisdiction through the use of the total amount control unit basin evaluation technique. By presenting customized management measures, we propose the guidelines that are necessary for determining more effective water environmental policies.

• The Journal of the Acoustical Society of Korea
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• v.41 no.3
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• pp.278-286
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• 2022

In this study, a 33-mode Free-Flooded Ring (FFR) transducer was designed to apply piezoelectric single crystal PIN-PMN-PT, which has high piezoelectric constants and electromechanical coupling coefficient. To ensure low-frequency high transmitting sensitivity characteristics with a small size of FFR transducer, the commercial FFR transducer based on piezoelectric ceramics was compared. To develop the FFR transducer with broadband characteristics, a piezoelectric segmented ring structure inserted with inactive elements was applied. The oil-filled structure was applied to minimize the change of acoustic characteristics of the ring transducer. It was verified that the transmitting voltage response, underwater impedance, and beam pattern matched the finite element numerical simulation results well through an acoustic test. The difference in the transmitting voltage response between the measured and the simulated results is about 1.3 dB in cavity mode and about 0.3 dB in radial mode. The fabricated FFR transducer had a higher transmitting voltage response compared to the commercial transducer, but the diameter was reduced by about 17 %. From this study, it was confirmed that the feasibility of a single crystal-applied FFR transducer with compact size and high-power characteristics. The effectiveness of the performance prediction by simulation was also confirmed.

• 한국노년학
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• v.29 no.2
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• pp.513-527
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• 2009

The purpose of this study was to verify the effect of senior simulation on geriatric unit nurses' attitude and job satisfaction toward the elderly with one group pretest-posttest design. The subjects of this study were the 30 nurses who are working in geriatric units in a general hospital in Daegu, Korea and who were well informed about the purpose of this study and allowed to join the study. The data were collected from August 23 to September 6, 2006. The experimental procedure was to do activities for daily living for 45 minutes wearing senior simulation suit. Self administered questionnaires were used to ask the nurses' attitude toward the elderly and job satisfaction in their work before, right after, and one week after senior simulation. According to the results of this study, there were significant changes in the geriatric nurses' attitude toward the elderly and job satisfaction after aging simulation implying that senior simulation is an effective intervention to facilitate nurses to do quality care for the elderly with sympathetic understanding and attitude. Senior simulation needs to be applied to geriatric education for the nursing students and health care providers who are involved in care for the elderly.

• The Journal of the Acoustical Society of Korea
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• v.29 no.6
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• pp.381-387
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• 2010

Both timbral features and spatial features are important in the assessment of multichannel audio coding systems. The prediction model, extending the ITU-R Rec. BS. 1387-1 to multichannel audio coding systems, with the use of spatial features such as ITDDist (Interaural Time Difference Distortion), ILDDist (Interaural Level Difference Distortion), and IACCDist (InterAural Cross-correlation Coefficient Distortion) was proposed by Choi et al. In that model, ITDDistswere only computed for low frequency bands (below 1500Hz), and ILDDists were computed only for high frequency bands (over 2500Hz) according to classical duplex theory. However, in the high frequency range, information in temporal envelope is also important in spatial perception, especially in sound localization. A new model to compute the ITD distortions of temporal envelopes in high frequency components is introduced in this paper to investigate the role of such ITD on spatial perception quantitatively. The computed ITD distortions of temporal envelopes in high frequency components were highly correlated with perceived sound quality of multichannel audio sounds.