• Journal of Advanced Marine Engineering and Technology
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• v.27 no.2
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• pp.280-288
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• 2003

We need refrigeration system which can maintain the freshness of agricultural products, because of being distance from a tiller to a consumer. Vacuum Pre-cooling system has an advantage in quality maintenance through vapid cooling down by using latent heat of evaporation of stored products. A number or thawing methods in current use have also several disadvantages in thawing time. discoloration mass loss caused by drying, capital costs and running cost. These damages are, it is claimed, either eliminated or improved by the vacuum thawing system. An experimental study on the pre-cooling for the bean sprouts and cabbage, and thawing for hairtail and croaker by the low temperature vacuum system were carried out. The cabbage cooling time with this Pre-cooling vacuum system took about 60 minutes to reach from $23.2^{circ}C to 4.5^{\circ}C$ at 5 mmHg abs. ($6.66\times10^{-4}$ MPa). The croaker thawing time with this low temperature vacuum thawing system took about 170 minutes to reach from $-10.3^{circ}C to -0.8^{\circ}C$ at 20 mmHg abs ($2.67\tiems10^{-3}$MPa). The vacuum Pre-cooling and thawing system have merits compared with present systems in their short intervals to cool down and to thaw without any quality losses.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.2
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• pp.224-233
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• 2016

The objective of this study was to develop an artificial neural network (ANN) model for the acoustic identification of commercially important fish species in Korea. A broadband echo acquisition and processing system operating over the frequency range of 85-225 kHz was used to collect and process species-specific, time-frequency feature images from six fish species: black rockfish Sebastes schlegeli, black scraper Thamnaconus modesutus [K], chub mackerel Scomber japonicus, goldeye rockfish Sebastes thompsoni, konoshiro gizzard shad Konosirus punctatus and large yellow croaker Larimichthys crocea. An ANN classifier was developed to identify fish species acoustically on the basis of only 100 dimension time-frequency features extracted by the principal components analysis (PCA). The overall mean identification rate for the six fish species was 88.5%, with individual identification rates of 76.6% for black rockfish, 82.8% for black scraper, 93.8% for chub mackerel, 90.6% for goldeye rockfish, 96.9% for konoshiro gizzard shad and 90.6% for large yellow croaker, respectively. These results demonstrate that individual live fish in well-controlled environments can be identified accurately by the proposed ANN model.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.1
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• pp.6-10
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• 1986

The feasibility of passive detection of fishes which had been caught in the fishing grounds near the Korean peninsula was theoretically investigated. Considering the commercial importance and the acoustical informations readily identified, although many species of fish make noise, Croaker is clarified to be a representative fish for passive fish detection. Assuming a source level of the sound produced by croakers is given as 150-18OdB (re 1l'pa, 500 Hz bandwidth), The range detected by a passive line array sonar is estimated to be about 3-20km. In addition, the tonal noise (700~800Hz) made by croaker that is easily separated from underwater noise is expected to increase the ability to discriminate from the other species of fish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.650-655
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• 2020

Chilsan-do Island, South Korea, has previously been identified as one of the biggest spawning sites of the small yellow croaker Larimichthys polyactis in the Yellow Sea. To determine whether Chilsan-do still serves as a spawning site for L. polyactis, three to five stations around Chilsan-do Island were surveyed for eggs from April to June (the main spawning season of L. polyactis) in 2019, using an RN80 net. For the first time, three L. polyactis eggs were identified at two stations, located just in front of Chilsan-do Island and between Chilsan-do and the coastline, only in May. The diameter of L. polyactis eggs (1.26-1.34 mm) was very similar to those of Collichthys niveatus (1.30-1.37 mm) and Setipinna tenuifilis (1.34-1.35 mm). During the survey period, the sea surface salinity remained constant (32.0-32.1 psu), but the sea surface temperature (SST) rapidly rose from 13.6-13.7℃ in April to 22.1℃ in May. Our findings suggest that L. polyactis still spawns near Chilsan-do Island today, but on a very small scale, and that changes in SST promote spawning of L. polyactis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.6
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• pp.939-944
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• 1994

The change of major organic acid contents were examined in mackerel, pacific yellow croaker and brown sole on heating conditions. The organic acid contents of mackerel were the higher that the others. The content of lactic acid was the highest in all samples commonly and that of succinic acid was second level and these organic acids were over 95% of total organic acid. The content of ${\alpha}-ketoglutaric$ acid was higher acid content was greater with higher heating temperature. Decreasing of organic acid content was higher at steamed and first heating than warmed and rewarmed.

• Korean Journal of Ichthyology
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• v.29 no.2
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• pp.109-116
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• 2017

We investigated maturation and spawning of Miichthys miiuy in the south-western water of Korea, based on samples collected by stow net from August 2015 to December 2016. We analysed monthly changes in maturity stage, gonadosomatic index (GSI), total length (TL) at 50% group maturity. The spawning period was August to October. We estimated the TL at 50% group maturity as 54.8 cm for females and 49.0 cm for males.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.3
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• pp.205-213
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• 2022

The experimental fish transplanted from China in 2015 was used after seedling production and cultivated. Breeding management for experiment was carried out from October 2020 to February 2021. Also, it succeeded in inducing artificial maturation three to four months earlier than wild broodstock and secured good quality fertilized eggs. The average size of fertilized eggs was 1.22 mm, at 20℃ Blastodisc (15 minutes post-fertilization), 2 cell (50 minutes), 4 cell (1 hours), 8 cell (2 hours), 16 cell (2 hours and 30 minutes), 32 cell (2 hours and 50 minutes), morula (3 hours), blastula (8 hours), gastrula (15 hours), skull formation (20 hours), organ formation (30 hours) and hatching yolk larvae stage (35 hours). The total length of the just hatched larvae were 2.50 ± 2 mm, and then gain growth of 42.5 mm by 60 days, reaching 45 ± 5 mm.

• Journal of the East Asian Society of Dietary Life
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• v.8 no.4
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• pp.422-429
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• 1998

The content of zinc and copper were analyzed and compared for five favorite traditional Korean dishes. The purpose of the research was to substantiate traditional Korean foods, which are good sources of these two minerals, to emphasize the importance of the minerals and to improve nutritional conditions. Foods were collected from institutional food services and Korean restaurants. The result of the analysis of the minerals are listed below. 1. When the survey was done on the preference and the frequency of intake of 106 Korean traditional dishes, the most popular food item was soybean paste stew (doenjangchigae); the second, barbecued beef (pulgogi): the third, cooked rice with assorted vegetables (pibimpap): the fourth, grilled fishes : the fifth, spicy beef vegetable soup (yukkaejang). The frequency of intake of eating these dishes was also very high. 2. The average one serving portion of each of the five dishes from institutional food services and Korean restaurants are as follows. The average one serving size of cooked rice with assorted vegetables of the two systems were 451.2g and 403.0g; spicy beef vegetable soup, 379.3g and 512.3g; soybean paste stew, 292.0g and 278.8g; barbecued beef, 76.1g and 202.5g: grilled croaker(chogi, fish), 47.5g and 36.5g, and grilled spanish mackerel(samchi, fish), 60.0g and 250.0g. The differences of the average one serving portion between the two systems were very significant. 3. The total average zinc content of each of the five dishes from the two different systems were analyzed. The zinc content of cooked rice ith assorted vegetables from institutional food services was 4.3mg and that from Korean restaurants was 2.9mg; spicy beef vegetable soup, 1. 7mg and 3.2mg: sybean pste stew, 1.4mg and 1.6mg: barbecued beef, 1.9mg and 4.3mg; grilled croaker, 0.5mg and 0.4mg; grilled spanish mackerel, 0.8mg and 2.7mg. The difference between the average of total zinc content of two systems were not statistically significant. 4. The average total copper content of each item from the two different systems were compared. The average total copper content of barbecued beef from institutional food services was 692.4$\mu\textrm{g}$ and that from Korean restaurants was 502.5$\mu\textrm{g}$. The value of the institutional food services system was significantly higher(p＜0.05). Spicy beef vegetable soup, 161.1$\mu\textrm{g}$ and 208.3$\mu\textrm{g}$: soybean paste soup, 290.5$\mu\textrm{g}$ and 308.5$\mu\textrm{g}$; barbecued beef, 217.7$\mu\textrm{g}$ and 339.l$\mu\textrm{g}$: grilled croaker, 51.7$\mu\textrm{g}$ and 44.l$\mu\textrm{g}$; grilled spanish mackerel, 92.0$\mu\textrm{g}$ and 265.2$\mu\textrm{g}$. The difference of the two systems was not significant. 5. The zinc contents per 100g each of five traditional Korean dishes were barbecued beef, 2.2mg, grilled spanish mackerel, 1.2mg, grilled croaker, 1.1mg, cooked rice with assorted vegetables, 0.8mg, soybean paste stew, 0.6mg, spicy beef vegetable soup, 0.5mg. The copper contents were; barbecued beef, 203.0$\mu\textrm{g}$, cooked rice with assorted vegetables, 138.7$\mu\textrm{g}$, grilled spanish mackerel, 137.9$\mu\textrm{g}$, grilled croaker, 119.l$\mu\textrm{g}$, soybean paste stew, 105.l$\mu\textrm{g}$, spicy beef vegetable soup, 40.5$\mu\textrm{g}$.

• Korean Journal of Food Science and Technology
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• v.34 no.5
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• pp.762-769
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• 2002

As a preliminary test for defining intact yellow croaker pigment, the pigment was analyzed by column chromatography and UV-vis spectrophotometry. All maximum absorbance wavelengths commonly showed three maximum absorbance ranges, similar to those of carotenoid, suggesting that the tested pigment may be carotenoid. We detected total six peak RT values in the chromatogram through PDA-HPLC under gradient mode (behavior A at 10% for initial 2 min and changed to behavior B for 60 min). Most pigments were detected at the peak with 3.27 RT value. Because seven peaks were detected under gradient mode and three under isocratic mode [methanol : methylene chloride (90 : 10, v/v)], gradient mode was determined to be more appropriate for quantitative analysis. By the comparison test of RT values among yellow pigment in croakers and reference pigments, such as zeaxanthine, ${\beta}-cryptoxanthine$, ${\beta}-carotene$, and astaxanthin, only ${\beta}-cryptoxanthine$ was detected in the white croaker, whereas such pigment of yellow croaker having RT value of 31.02 was not detected. Therefore, RT value was found to be applicable for detecting adulterated croaker.

• Food Science and Preservation
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• v.10 no.2
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• pp.154-157
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• 2003

To examine the quality changes of three typical fishes under usual storage conditions during marketing, we determined the total bacterial counts and pH values during storage of mackerel, croaker, and saury. Mackerels were stored at 0$^{\circ}C$ and on ice at 19$^{\circ}C$, which is the usual storage condition in a local market and croakers and saury were stored at 0$^{\circ}C$ and 4$^{\circ}C$. Total bacterial counts of mackerel, croaker, and saury were 3,2${\times}$10$^3$, 2.9${\times}$10$^3$, and 2.8 x 10$^4$CFU/g at the time of storage respectively. Total bacterial counts of mackerel stored on ice at 19$^{\circ}C$ increased during storage and reached to 8.4 x 10$\^$6/ CFU/g at day 6, while those stored at 0$^{\circ}C$ decreased up to 2 days of storage and increased to 5.6 ${\times}$ 10$^4$CFU/g. For croaker and saury, total bacterial counts at 0$^{\circ}C$ were 2.5 ${\times}$ 10$\^$5/ and 2.1 x 10$\^$5/ CFU/g at day 6, respectively, while those stored at 4$^{\circ}C$ had 3.6 x 10$\^$6/ and 2.6 ${\times}$ 10$\^$5/ CFU/g. the pH value or mackerel was 5.56 at the time or storage, yet it increased to 6.04. The pH changes of croaker and saury had a similar pattern with that of mackerel, which increased with time of storage. These results suggest that storage of fishes at 0$^{\circ}C$ should be better than those at 4$^{\circ}C$ or on ice at 19$^{\circ}C$ in terms of microbial safety as well as quality and shelf-life of fishes.