• Journal of the Korean Society of Marine Environment & Safety
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• v.6 no.2
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• pp.57-66
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• 2000

The argument about enlarging or limiting the function of the Korea Maritime Police. Agency (KMPA) has been and will be repeated. In this paper, the author highlights the internal and external issues facing KMPA, stemming partly from deficiencies of its struggles for advancement of the organization and partly from shortcomings of political support far it. And he urges KMPA to change the organizational culture for maintaining its identity and characteristics as a lead maritime agency by practising a scientific management system for maximizing cost-effectiveness of its administrative resources. In addition, he also suggests that KMPA adopt the Total Quality Management System for quality improvements in services and greater efficiency in its organizational structure to meet the future competition in the changing political and legal environment. he concludes by providing a 6-point vision statement for KMPA from the standpoint of favoring enlarging the function of KMPA.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.7
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• pp.609-614
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• 2011

The ship working environment of combat service support boat is much inferior to the ground working environment. For this reason, the crew of a combat service support boat suffer from an occupational disease such as hardness of hearing. Owing to its small size and low status, the improvement of its working and residential environment was occasionally ignored and its indoor noise was not fully investigated. In this study, for improving its residential environment indoor, the indoor noise of its shipboard compartments was analysed. These studies define the indoor noise level of combat service support boat is very high and some of indoor noise is exceeded the criteria for ship noise. Compared with marine police vessels, the indoor noise levels of marine police vessels are higher than the level of combat service support boat.

• Proceedings of KOSOMES biannual meeting
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• 2001.05a
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• pp.169-183
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• 2001

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.97-109
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• 2005

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.234-240
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• 2011

In order to obtain the fundamental data about the behavior of sharks by underwater audible sound, this experiment was carried out to investigate the auditory characteristics of tiger shark Scyliorhinus torazame which was caught in the coast of Jeju Island by heart rate conditioning method using pure tones coupled with a delayed electric shock. The audible range of tiger shark extended from 80Hz to 300Hz with a peak sensitivity at 80Hz including less sensitivity at 300Hz. The mean auditory thresholds of tiger shark at the frequencies of 80Hz, 100Hz, 200Hz and 300Hz were 90dB, 103dB, 94dB and 115dB, respectively. The positive response of tiger shark was not evident after the sound projection of over 300Hz. At the results, the sensitive frequency range of tiger shark is narrower than that of fish that has swim bladder. In addition, it is assumed that the most sensitive frequency in auditory thresholds of Chondrichthyes is lower than that of Osteichthyes. Critical ratios of tiger shark measured in the presence of masking noise in the spectrum level range of about 60-70dB (0dB re $1{\mu}Pa/\sqrt{Hz}$) increased from minimum 27dB to maximum 39dB at test frequencies of 80-200Hz. The noise spectrum level at the start of masking was distributed at the range of about 65dB within 80-200Hz.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.2
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• pp.132-141
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• 2017

The objective of this study was to provide fundamental information on fish swimming behavioral properties. Acoustic data was collected at nighttime from the $10^{th}$ to $12^{th}$ March, 2016 near Yokji Island in the South Sea of South Korea, and was analyzed using the fish track technique. This technique is to identify groups of single targets, which shows a pattern of systematic movement. As a result, the differences of the behavioral properties such as depth, swimming speed, vertical direction, horizontal direction, tortuosity, and depth change among days were minor; however, statistical results (Welch analysis of variance) showed significant difference between days. Especially, the target strength (TS) of the $11^{th}$ were significantly different from the $10^{th}$ and $12^{th}$. It could be assumed that gizzard shad, which was the dominant species from the catch on the $11^{th}$ March, might have affected this difference. The correlation between TS and other properties was very week. The significant difference seemed even small differences of average values because of the large data volume.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.386-395
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• 2017

For scientific research, a number of acoustic surveys using commercial echosounders equipped in fishing vessels were conducted throughout the world; however, few studies were performed in South Korea. Hence, this research is an preliminary study for presenting the application of a sounder from a fishing vessel. The fishing operations using a pair trawler (7 Cheonghae) was conducted in the Northwest-Western sea of Jeju Island from 20 to 23 April, 2016. Substantial impulse noises and attenuated signals were eliminated by the latest algorithms. Acoustic signals were grouped into the fish aggregations and long layer-like signals. The fish aggregations appeared between 30 and 60 m, and long layer-like signals showed the diurnal vertical migration. Energetic, morphological and positional properties of the fish aggregations and layer-like signals were described. The fish aggregations appeared mainly between sunrise and sunset; however layer-like signals tended to be presented regardless of time in consideration of the time series analysis. On the basis of the consignment sales, Scomberomorus niphonius, the target species of F/V 7 Cheonghae, was the highest catch with 4,280 kg (74.6%) and might have appeared in fish aggregations and layer forms.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.1
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• pp.39-49
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• 2019

Acoustics are increasingly regarded as a remote-sensing tool that provides the basis for classifying and mapping ocean resources including seabed classification. It has long been understood that details about the character of the seabed (roughness, sediment type, grain-size distribution, porosity, and material density) are embedded in the acoustical echoes from the seabed. This study developed a sophisticated yet easy-to-use technique to discriminate seabed characteristics using a split beam echosounder. Acoustic survey was conducted in Tongyeong waters, South Korea in June 2018, and the verification of acoustic seabed classification was made by the Van Veen grab sampler. The acoustic scattering signals extracted the seabed hardness and roughness components as well as various seabed features. The seabed features were selected using the principal component analysis, and the seabed classification was performed by the K-means clustering. As a result, three seabed types such as sand, mud, and shell were discriminated. This preliminary study presented feasible application of a sounder to classify the seabed substrates. It can be further developed for characterizing marine habitats on a variety of spatial scales and studying the ecological characteristic of fishes near the habitats.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.2
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• pp.235-244
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• 2015

The multi-frequency characteristics of anchovy schools were investigated using six acoustic lines collected at 38 and 120 kHz while a primary trawl survey was conducted from 14 April and 18 April of 2014 in off the coast of Tongyeong and Geo-je. Here, the frequency characteristics mean ${\Delta}MVBS$ that is the difference of Mean Volume Backscattering Strength at two frequencies. To use the characteristics effectively, the optimal cell size ($10{\times}2m$) was determined by examining several different cell sizes in consideration with the shapes of fish schools and the ${\Delta}MVBS$ pattern. By examining 6 histograms of ${\Delta}MVBS$, afternoon groups were occupied more in the ${\Delta}MVBS$ range of -6~-4 dB than that of -4~-2 dB, comparing to morning groups. The ${\Delta}MVBS$ range of the morning groups was between -16.9 dB and 11.6 dB, and that of the afternoon groups -16.7 dB and 13.0 dB. The average and standard deviation were $-3.9{\pm}3.6$ dB in the morning and $-4.1{\pm}3.4$ dB in the afternoon, suggesting that morning groups were 2 dB higher than afternoon groups. The ${\Delta}MVBS$ range of all anchovy schools regardless of morning and afternoon was between -16.9 dB and 13.0 dB, their average ${\Delta}MVBS$ was $-4.1{\pm}3.5$ dB. The characteristics can support to identify anchovy species in the waters where multiple fish species are distributed. It is hoped that this study presents the availability and benefit of acoustic data from a primary trawl survey.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.3
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• pp.232-240
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• 2016

Marine casualties originated from fishing vessels occupied about 71.2% of the whole marine casualties in Korea from 2008 to 2014, which has not changed much for a long time. Therefore, a pragmatic counterplan to decrease in casualties in fishing vessel is indispensable for reduction of marine casualties in Korea. Since the casualties occurred by fishing vessels may incline to a specific type of casualties according to the difference in the operating type; in this paper, 11 fishing types which occurred casualties frequently in numbers and occupied ratio were selected. Since the most frequent occurring casualties in fishing vessels were from collisions and fire explosion in statistics from KMST (2008~2014), the study focused on them. The collision is given a great deal of weight in all the casualties mostly due to the negligence of duty regardless of the job types. Gill netter, trap fishing boat, jig boat, multiple fishing boat and stow netter have their own specific causes of casualties in collision according to the operating types. The cause of fire explosion was mainly due to poor inspection and maintenance the electric cord. For this reason, it may be necessary for an operator to make strict precaution on the other vessels under way systematically, keep the regulation for preventing collisions, and for an engineer on watch to make a check the electricity periodically to reduce the fire explosion.