• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.6
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• pp.799-805
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• 2017

The whistle sounds of three Beluga whales Delphinapterus leucas were recorded four times, for an hour each time, in 2016 and analyzed to obtain the most stable and basic acoustic characteristics of the whales in captivity. This study investigated the whistle characteristics of beluga whales and the relationship between whistle sounds and behavior to understand the meaning of the whistle sounds. The whistles were classified into six types (flat, ascending, descending, hump, dip, and wavy type) by their frequency contour and shape. The most common type was the ascending type, accounting for>30% of total whistles. The fundamental frequency of whistles was 2.0-8.6 kHz. Four types of behavior were related with the sounds of beluga whales (aggressive, submissive, affiliative, sexual behavior). A flat whistle was the most recorded in the group and an aggressive act was observed in association with the flat whistle. A dip whistle were recorded more when submissive acts were observed.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.2
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• pp.123-136
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• 2015

The present study numerically investigates the effect of shield on the flow characteristics of Hartmann whistle. The flow characteristics of un-shielded Hartmann whistle are compared with whistles of different shield heights 15 mm, 17 mm, 20 mm, 25 mm and 30 mm. The comparison of Mach number contours and transient velocity vectors of shielded Hartmann whistles with un-shielded ones for the same conditions reveal that the presence of shield causes the exiting jet to stick to the wall of the shield without causing spill-over around the cavity inlet, thus sustaining the shock oscillation as seen in the unshielded Hartmann whistle, which has intense flow/shock oscillation and spill-over around the cavity mouth. The velocity vectors indicate jet regurgitance in shielded whistles showing inflow and outflow phases like un-shielded ones with different regurgitant phases. The sinusoidal variation of mass flow rate at the cavity inlet in un-shielded Hartmann whistle indicates jet regurgitance as the primary operating mode with large flow diversion around the cavity mouth whereas the non-sinusoidal behavior in shielded ones represent that the jet regurgitance is not the dominant operating mode. Thus, this paper sufficiently demonstrates the effect of shield in modifying the flow/shock oscillations in the vicinity of the cavity mouth.

• Korean Journal of Culture and Social Issue
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• v.23 no.1
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• pp.25-52
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• 2017

The purpose of this study is to explore the motivation for, expectations of, consequences of, and attitudes toward whistle-blowing. that whistle-blowers experience in the whistle-blowing process, and clarify the difference between the ideal and reality. Fourteen official whistle-blowers were interviewed and qualitative data were analyzed based on phenomenological approach. As a result, motivational themes appeared such as professional spirit and personal values. They also tried to pursue public interest such as social changes as well as public support for them. In addition, the participants believed that the cultural characteristics of Korean society such as vertical collectivism are responsible for the gap between ideals and reality of whistle-blowing. In particular, They also suggested a few alternative for reducing the gap.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.4
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• pp.271-277
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• 2002

This paper was described on the characteristics of bottlenose dolphin (Tursiops truncatus) whistle to develop a warning and attracting acoustic system which can be made friends woith environment and minimized to the fishing pollution from Cetaceans. The experiment for the acoustics of bottlenose dolphin whistle was carried out in dolphin performance hall at Seoul Grand Park during 18th~19th April, 2002. The frequency and the spectrum level of whistle a same pool were revealed 6~10KHz and 85㏈ but those revealed two harmonic waves a 6.7KHz and 21.3KHz for the frequency and 110㏈ and 94㏈ for the spectrum level, respectively, when a dolphin isolated from others. The range of frequency change of whistle was 3.86KHz and continuous time was 0.08 sec. The range of frequency change 10.20 KHz higher as 14.06 KHz and continuous time was 0.11sec longer as 0.19sec when a dolphin isolated from others. By the Mann-Whitney test for the result, there was a significant difference for the range of frequency change and continuous time between normal condition and when a dolphin was isolated from others. The pattern of whistle at the dolphin performance hall was five types and the frequency was getting increased slowly in the range of 5~10KHz at normal condition but there were pattern change of 5~20KHz at the isolated condition. Therefore it is thought that these experiments would be valuable for the development of acoustic system.

• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.491-496
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• 2004

The paper describes measurement techniques for an acoustic transfer characteristic of ship's bridge stimulated by a whistle sound The response sounds, according to the opening-shutting conditions of bridge doors for Training Ship ‘SAENURI’, are measured by B＆K 2260D equipment, and then the frequency responses are extracted by B＆K 7830 software. To evaluate the measured transfer characteristic, the 128th order FIR (Finite Impulse Response) filters, containing the different frequency characteristics, are constructed based on the frequency sampling-based design method Using evaluation indexes with six scales, psychological assessments by five subjects are carried out with test sounds which are obtained from convolving the source signal with FIR filters. As results of tests, the test sounds gives $A_S$ 3.3∼4.7 which means the psychological sense of ‘it is almost similar sound as original ones in a real world’, and thus it is clearly seen that the proposed method can be used for the measurement of an acoustic transfer characteristic of ship’s bridge.

• Journal of Environmental Science International
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• v.6 no.1
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• pp.9-16
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• 1997

We investigated and analysed the actual conditions and characteristics of railroad noise levels for 17 sites in the vicinity of the Seoul-Pusan Line. The results i,we summarized as follows : 11 Railroad noise level ranged to 64 ~ 74 $L_{eq}$ dB(A) at day time and ranged to 60 ~ 72 $L_{eq}$ dB(A) at night time. 21 Increased night noise level depend on the increase of trains passing at night time. 31 The major factor of Increased noise level in the vicinity of stations are using loudspeakers and stream whistle on trains. 4) Decreased effect of noise according to distance is able to be described quantitatively using regression equations of multiplicative model. $L_{eq}$=$78.59^{X-0.056}$, n =25, r=-0.994, s.e. =1.007 $P_{av}$ = $105.68X^{-0.073}$, n =25, r =-0.997, s.e. = 1.007 Also increased and decreased effect of noise according to floor in apartment Is able to be described quantitatively using regression equations of multiplicative model. $L_{eq}$ = $64.238X^{0.0567}$, n = 39, r = 0.787, s.e. = 1.004 $P_{av}$ =79.963X0.0524, n =39, r =0.689, s.e. = 1.056 5) Average noise level in high floor is over 70 $L_{eq}$ dB(A) at day and night time. so more detailed soundproofing countermeasured in high floors apartment is required.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1553-1558
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• 2014

The travel demand, peak hour ratio and forms of platform of urban railway stations are very different each other, also the users' behavior is. So the types of urban railway stations have to be classified according to these characteristics. However, the current methods of classification are arbitrary on the purpose of each studies and the legal standards are very simple; categorized by normal station vs. whistle station, types of trains, forms of platforms and shapes of architecture. This study clarifies the standards for classifying the types of urban railway stations, results the complete enumeration survey on all the urban railway stations in Seoul Metropolitan Area and makes the database based on the surveyed data, purposing on helping for making strategies and researching. On this study, utilizing the database which is established for this study, the correlation between the physical and geographical characteristics and users' travel patterns of urban railway stations is clarified by the statistical analysis. In the future, the statistical results will be helpful for making strategies and researching.

• The Journal of the Acoustical Society of Korea
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• v.41 no.2
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• pp.227-234
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• 2022

Covert Underwater Communication (CUC) signals should not be detected by other unintended users. Similar to the method used in Radio Frequency (RF), covert communication technique sending information underwater is designed in consideration of the characteristics of Low Probability of Detection (LPD) and Low Probability of Intercept (LPI). These conventional methods, however, are difficult to be used in the underwater communications because of the narrow frequency bandwidth. Unlike the conventional methods of reducing transmission power or increasing the modulation bandwidth, a method of mimicking the acoustic signal of an underwater mammal is being studied. The biomimetic underwater acoustic communication mainly mimics the click or whistle sound produced by dolphin or whale. This paper investigates biomimetic communication method and introduces research trends to understand the potential for the development of such biomimetic covert underwater acoustic communication and future research areas.

• The Journal of the Acoustical Society of Korea
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• v.38 no.1
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• pp.56-65
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• 2019

The Indo-Pacific bottlenose dolphins (Tursiops aduncus) are a toothed whale using echolocation clicks and have been studied continuously abroad. However, most studies on this whale's clicks were performed about captive animals and, in Korea, only the studies of the whistle sounds of this animal were done. In this paper, acoustic characteristics of clicks were analyzed about the free-ranging Indo-Pacific bottlenose dolphins living in the coast of the Jeju Island. Acoustic parameters such as signal duration, 1st and 2nd peak frequency, 3 dB and 10 dB bandwidth for acoustic characteristics were calculated and compared with those of Australian species. As a result, the signal durations had average of $38{\mu}s$ and most clicks were within range of $20{\mu}s-60{\mu}s$. The two types of bandwidths showed both narrowband and broadband characteristics, and bimodal signal characteristics were confirmed through the 1st peak frequencies(average of $96kHz{\pm}18kHz$) and the 2nd peak frequencies(average of $69kHz{\pm}19kHz$).

• Korean Journal of Culture and Social Issue
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• v.8 no.1
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• pp.79-101
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• 2002

The present study was to investigate the psychological characteristics of Urie(義理; interpersonal morality) in Korean interpersonal relationships in terms of qualitative approach and quantitative approach. In study 1, the authors developed an open-ended questionnaire focused on Urie behavior and not Urie behavior. The results revealed that helping, trusting, and caring behaviors and historicality were the key elements of Urie relationships. On the other hand, selfish and distrusting behaviors disrupted Urie relationships. In study 2, the authors conducted video experiment in order to study how the subjects interpret and understand Urie phenomenon. This video stimulus composed of love and friendship. The main characters showed their conflicts between love and friendship. Thus, subjects were asked to answer their interpretations and understandings about what was going on according to the scene. In study 3, we made three kinds of scenarios which were constituted in conflict situation between close friends who works together at their own company. If one asks some favors to you against social justice, how do you do? Most subjects evaluated the whistle blowing behavior as moral and just. However, they evaluated the insider as not good friend. They evaluated one who did favor even though that behavior was socially unjust as good friend and having Urie. Consequently, Korean people emphasize on their human relationships in everyday life. Urie relationship is built in close and Cheong relationship.