• Journal of Fisheries and Marine Sciences Education
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• v.25 no.2
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• pp.341-348
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• 2013

The auditory thresholds for 7 specimens of the sharp toothed eel Muraensox cinerus were measured at 5 frequencies by heartbeat conditioning method using pure tones coupled with a delayed electric shock. The audible range of the sharp toothed eel extended from 80Hz to 300Hz with the best sensitivity around 80Hz and 100Hz. In addition, the auditory thresholds over 200Hz increased rapidly. The mean auditory thresholds of the sharp toothed eel at the test frequencies of 80Hz, 100Hz, 200Hz and 300Hz were 87dB, 86dB, 105dB and 126dB, respectively. Auditory masking was determined for the sharp toothed eel by using masking stimuli with the spectrum level range of about 70~80dB (0dB re $1{\mu}Pa/\sqrt{Hz}$). According to white noise level, the auditory thresholds increased as compared with thresholds in a quiet background noise. The noise spectrum level at the start of masking was distributed at the range of about 64dB within 80~100Hz. Critical ratio ranged from minimum 24dB to maximum 40dB at test frequencies of 80Hz~200Hz.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.4
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• pp.479-486
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• 2012

In order to obtain the fundamental data about the behavior of conger by underwater audible sound, this experiment was carried out to investigate the hearing ability of Conger eel Conger myriaster which was in the coast of Jeju Island by heartbeat conditioning method using pure tones coupled with a delayed electric shock. The audible range of conger eel extended from 50Hz to 300Hz with a peak sensitivity at 80Hz including less sensitivity over 200Hz. The mean auditory thresholds of conger eel at the frequencies of 50Hz, 80Hz, 100Hz, 200Hz and 300Hz were 105dB, 92dB, 96dB, 128dB and 140dB, respectively. The positive response of conger eel was not evident after the sound projection of over 200Hz. At the results, the sensitive frequency range of conger eel is narrow in spite of swim bladder. Auditory masking was determined for Conger eel by using masking stimuli with the spectrum level range of about 60~70dB (0dB re $1{\mu}Pa/\sqrt{Hz}$). According to white noise level, the auditory thresholds increased as compared with thresholds in a quiet background noise including critical ratio at 68dB of white noise from minimum 26dB to maximum 30dB at test frequencies of 80Hz and 100Hz. The noise spectrum level at the start of masking was distributed at the range of about 68dB within 80~100Hz.

• Bulletin of the Korean Chemical Society
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• v.21 no.2
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• pp.264-266
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• 2000

• 한국해양학회지
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• v.15 no.2
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• pp.108-111
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• 1980

The sampling was made by a kind of trap nets and an electric fishing apparatus in the lagoons of Arcachon Bay. Length frequency distributions obtained by two gears are combined to propose more reliable length composition of the population. The biomass was estimated by the capture and recapture method in a limited area with electric fishing apparatus, and it was redressed based on the corrected length composition. It showed approximately 638kg/ha in the deeper parts of the lagoons. It suggests that the lagoons of Arcachon Bay contain relatively high density of eels.

• Journal of Aquaculture
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• v.17 no.4
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• pp.262-267
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• 2004

Physiological responses (oxygen consumption, ammonia excretion, hemoglobin, red blood cell and white blood cell) of cultured eel, Anguilla japonica to vibration stress were studied in an indoor experimental system. Vibration of 76-93 dB (V) from an electric vibrator was provided in 15-minute intervals during daytime (0800-1800) over a ten day period. Oxygen consumption before the beginning of the experiment (0 day) was 83.9 mg $O_2$$.$kg$^{-1}$ ㆍhr$^{-1}$ . After 1, 5 and 10 days of stress respiration rate decreased by 37.5, 53.7 and 70.5%, respectively. Ammonia excretion showed a similar pattern to that of oxygen consumption. Ammonia excretion decreased by 80.1 % following 10 days of vibration stress. Blood hemoglobin concentration also decreased at 1, 3 and 10th day were 29.4% on day 1,83.9% on day 3 and 87.9% by day 10, while red blood cell counts at day 1 and day 10th were 59.8% and 84.7% lower than initial counts, respectively. The white blood cell count increased by 191.2% at day 7, dropping to 41.5% at day 10. Physiological activity was reduced by 50% following 3.4 days of vibration stress.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.260_261
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• 2009

현재 국내 지중배전계통은 지역별 공급신뢰도의 차등이 없는 분기선 연계 방식을 획일적으로 적용해 오고 있다. 이에 따라 도시 중심부나 외곽 지역 그리고 지방도시에 이르기까지 동일한 공급신뢰도를 갖는 배전계통 방식으로 고객에게 전력을 공급하고 있다. 그러나 해외 선진국의 배전계통 구성방식을 살펴보면 우리나라와 같이 단일 배전계통 구성 방식을 적용하는 경우는 거의 드물고 지역 및 부하 특성에 따라 배전계통 구성 방식을 달리하는 다양한 방식을 채택하고 있다. 따라서 본 논문에서는 신 지중배전계통의 국외사례에 대해 검토를 통해 국내 신도시에 적합한 신뢰도가 높으면서도 경제적인 신 지중배전계통에 대해 제시하였다.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.319-322
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• 1990

Self-controlled permanent magnet synchronous motor (PMSM) has similar operating characteristics as seperately excited dc motor. It is favored in servo applications due to its improvement of efficiency and maintenance. This paper presents completely digitalized controller using microprocessor and voltage fed inverter. The speed control system for PMSM is implemented. To control the motor speed, the control system regulates the magnitude of Inverter output voltage by regular-sampled PWM method to generate sinusoidal PWM wave with microprocessor. And to keep the range of inverter switching frequency, it varies the number of pulse train according to the speed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.40-45
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• 2010

In order to establish the electric distribution system economically and operate efficiently, it becomes important to calculate energy losses of the system more accurately. This importance is not only related for the engineering of utilities' power network but also for the consumers' electric system. The Distribution Loss Factor (DLF) is the fundamental element of calculating the energy losses occurred through the electric system including the electric lines and equipments. Up to now, the DLF is calculated by empirical formulas using the correlation between the DLF itself and Load Factor. However, these methods have some limitations to reflect the various characteristics of the system and the load. In this regard, the novel method proposed here is developed to yield more accurate result of DLF which actively interacting with the characteristics and load patterns of the system. The improvement of accuracy is very significant according to the results of verification presented at the end of this paper.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.489-490
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• 2018

As the number of electric vehicles (EV) increases, there is an increasing interest in the post-vehicle application of the EV batteries. For the second use application of EV batteries, the state of health (SOH) at the end of automotive service has to be evaluated differently from the automotive perspective. It will be helpful to consider the driving conditions of EVs in understanding the performance deterioration trend of the battery. In this paper, we acquired the battery status information in real time during driving and compared the characteristics by the driving routes. The SOH from the BMS can be rescaled to percentage ratio to give a more general idea about the performance degradation.

• Journal of Marine Life Science
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• v.3 no.2
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• pp.81-86
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• 2018

The purpose of this study is to determine the effects of vibration on primary (e.g. plasma cortisol), secondary (e.g. plasma glucose, aspartate aminotransferase (AST), alanine aminotransferase (ALT), Na⁺, K⁺ and Cl^- and tertiary (e.g. mortality) stress responses in cultured eel, Anguilla japonica. For this purpose, three groups (including one control group and two stress groups) were set up. The control group was made exposed to vibration corresponding to 48 decibel (dB, V) (produced using electric vibrators) for 15 minutes per hour every day, and the two stress groups was made exposed to vibration corresponding to 58 and 68 dB (V) (produced using the same electric vibrators), equally, for 15 minutes per hour every day. Blood was sampled at day 0 (before starting vibration stress tests, BS), and days 1, 3, 5, 7, 9 and 11 (after starting vibration stress tests). As a result, plasma cortisol showed trend to continuously rise by consecutive stress from 4.1±0.1 ng/ml in BS. In 48 dB group (control), cortisol showed the highest level with 7.6±0.9 ng/ml after 7 days (p<0.05), but at 9 and 11 days was not significantly compared with BS level. In 58 dB group, the cortisol showed the highest level with 43.1±4.8 ng/ml after 1st day. Cortisol of 68 dB group increased significantly during the experimental period (14.4±2.3~32.0±5.7 ng/ml) (p<0.05). In 58, and 68 dB groups during the experimental period differed significantly compared to 48 group (p<0.05). Glucose in 48 dB were increased from 42.0 ±5.7 (BS) to 52.5±2.1 (1 day), the level was not significantly from 1 to 11 days. Glucose in 58 and 68 dB groups was increased significantly than BS during experimental period (p<0.05). K⁺ in 68 dB increased significantly (p<0.05) from 2.3±0.2 mE/ql (BS) to 3.3±0.5 mE/ql at 5 days. In 48 and 58 dB groups during the experimental period differed significantly (p<0.05). Na⁺ and Cl^- levels were not differed significantly during the experimental period. AST and ALT in 58 and 68 dB groups showed trend to continuously rise by consecutive stress. At 7 and 9 days in AST, between 48, 58 and 68 dB groups differed significantly (p<0.05). In 48, 58 and 68 dB groups at 1 day, blood hematocrit increased significantly higher than BS. The 11 days after vibration stress, the mortality in 48, 58 and 68 dB groups was 1.1, 5.1 and 5.8%, respectively. The present results have shown that A. japonica exhibited ''typical'' physiological responses when exposed to chronic vibration stress. These data suggested that chronic vibration stress caused substantial stress in the fish; especially the persisting elevated plasma AST and ALT levels observed would be expected to adverse effect. In conclusion, chronic vibration stress could greatly affects the hematological characteristics in A. japonica.