• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.1
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• pp.1-9
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• 2000

Vertical temperature distributions in muddy intertidal sediments near the Jebu Island on the west coast of Korea were obtained during the period of ebb tide which occurred in day time. The observations of mud temperature were made with thermistor embedded probe at 2cm interval for 18cm-layer of sediment for five different months of the year. Temporal changes in the vertical profile of the sediment temperature are strongly depend on the air temperature, the previous time of flood tide and the time of ebb tide. Heat exchanges in the surface layer (0-2 cm) in terms of magnitude and direction are greater than and opposite to those in the deeper sediment layer (8-12 cm), respectively and do not show any significant seasonal variations. In general, the surface layer gains heat while the deeper layer loses the heat. By using the 1-D diffusion equation temporal vertical profiles of the sediment temperature were obtained and were compared with the observed ones. The results show that in the sediment layer below 4 cm-depth the heat transport is predominantly by molecular diffusion. The average magnitude of heat flux into the sediment layer (0-18 cm) during the ebb tide when the mudflats were exposed in the middle of the day were between 4.1 and $28.9\;W/m^2$.

• Korean Journal of Food Science and Technology
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• v.50 no.2
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• pp.165-171
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• 2018

Atmospheric-pressure plasma (APP) was applied to determine quality characteristics of brown rice (BR) and white rice (WR) of Samkwang and Palbangmi. APP (250 W, 15 kHz, ambient air) was generated and dielectric barrier discharge was applied for 0, 10, and 20 min for 2 weeks at 4 and $25^{\circ}C$. The growth of total aerobic bacteria and mold increased depending on the storage. Water content of BR and WR decreased by storage temperature and periods. No viable counts were detected for molds by APP-treated 20 min at $4^{\circ}C$. Changes in protein and damaged starch contents in plasma were not observed. Amylose contents were not changed, but WR (Palbangmi) showed a tendency to increase. The results show that APP improved the microbial quality of BR and WR of Samkwang and Palbangmi, although further studies should be conducted to determine change in quality by APP.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.2
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• pp.117-123
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• 2001

Anchovy scoop nets, a kind of lift net have been used in the coastal area of Cheju and South sea of Korea. An incandescent lamp(AC 100V, 1kW) is being used as a fishing lamp for gathering anchovy. Fishing lamp was installed at 1m ahead of the prow and 1.5m higher than the water surface. The fishing lamp let fish school rise to the water surface and attract to bag net. Accordingly, a successful anchovy catching depends on controling of fishing lamp. On the study, the distribution of spectral irradiance illumination of incandescent lamp(1kw) and the irradiance efficiency of reflection plate were analyzed and discussed to investigate the ability of fishing lamp which can attract anchovy school effectively. The results obtained are summarized as follows : 1. Around 180% of irradiance efficiency of incandescent lamp was increased by using the reflection plate. The light of lamp was radiated into water with circular shape. 2. The irradiance illumination of incandescent lamp in air was a maximum in wave length of 994nm but it was 690nm at 0.5m and 1.0m of water depth. 3. The relationship between water depth(x) and water illumination(y) of vertical light is represented as follows : y=146.03e supper(-0.37x) 4. The light of incandescent lamp(1kW) pass through much better into vertical direction than horizontal but it was estimated that the light was not able to reach depth of 20m.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.1
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• pp.1-7
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• 1997

We have monitored nutrients, chlorophyll, suspended solids, and salinity in the Keum Estuary to understand the temporal fluctuation of oceanographic parameters and to illustrate any variation due to the gate operation of the Keum River Dike from June, 1995 to September, 1996, approximately for 500 days. Tidal range is used as the key factor to explain the fluctuations and atmospheric parameters such as air temperature, wind velocity and rainfall are also used supplementally. The fresh water discharge was selected as another major impact on the estuarine environment due to the gate operation of the Keum Dike. In addition, daily variation by tidal cycle was investigated twice in April and July, 1996. In diurnal variation, salinity was positively correlated with tidal elevation, whereas negatively correlated with nutrients. Relatively high suspended solid and chlorophyll contents were found in the period between high and low tide. In 500 days continuous observations, salinity was negatively correlated with the volume of fresh-water discharge, but positively correlated with nutrients. A major chlorophyll bloom occurred in spring. A similar pattern of variation was observed between suspended solid and the neap-spring tidal cycle. In comparison with the data of the Keurn Estuary before the gate operation of the Keum River dike, fresh-water discharge predominated other environmental factors during the rainy season. In addition, the velocity of tidal current and the concentration of suspended solid were decreased, while nutrients and chlorophyll contents were increased.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.1
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• pp.39-52
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• 2000

The triad interactions have been known to be important only for shoaling waves or finite depth wind waves. In deep water, they are insignificant compared with the quadruplet interactions in respect to the evolution of wind waves due to energy transfer among the wave components. However, the triad interactions may be important even for deep water waves because they may closely be related to the wave steepness, which definitely affects wave breaking, drag of air flow over t.'Ie sea, or navigation of ships, especially during the early stage of the development of wind waves. This study reports a series of laboratory experiments, whose data are subjected to bispectral analyses to investigate the triad interactions of deep-water wind waves. It is found that the bicoherence at the spectral peak frequency and the wave steepness are almost directly proportional, indicating that the steep waves with peaked crests and flat troughs are resulted from the triad interactions. Both bicoherence and wave steepness increase with the wave age during the early stage of wave generation and then drop off as the waves grow old. It seems that the energy of the secondary spectral peak developed by the triad interactions during the early stage of wave generation is redistributed to the neighboring frequencies by the quadruplet interactions during the later stage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.3
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• pp.219-225
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• 2011

The physicochemical properties of rice endosperm from five rice varieties and effects of milling on baking bread properties of rice flour were investigated. Five rice varieties exhibited different level of amylose content. The ratio of longer amylopectin chain length to the distribution of endosperm starches was the highest in Goami3. According to the RVA measurement of rice flours, the pasting temperatures of Seolgaengbyeo and Goamibyeo were lower than those of the other rice varieties. There were differences in the changes of swelling power of rice flour under increasing temperature. Each rice flour sample for bread-making was processed into two different particle size by using an air-classification mill, and significant differences were observed among cultivars in the average particle size and damaged starch content of rice flours. Rice flour of Seolgaengbyeo with fine particle size showed the highest value in specific volume after baking.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.6 no.1_2
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• pp.76-80
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• 1973

Cyclina sinensis is an edible bivalve inhabiting wide tidal flats which are exposed to the air at ebb tide along the western coast of Korea. Over the period of June to September 1971, some specimens from a tidal flat near Inchon were submerged in sea water with various concentrations of ammonium hydroxide added and careful observations were made on their fertilization, early development, and metamorphosis of the larvae. The highest rate of fertilization was demonstrated by individuals treated with 1/1000 normal solution of ammonium hydroxide and their fertilized eggs followed normal development, i.e., two cell stage 1.5 hours after fertilization, blastular stage after 4 hours, and trochophore stage after 6 hours. Within 24 hrs after fertilization C. sinensis larvae have acquired the form of early straight-hinge veliger with the mean prodissoconch I with the length of $110\mu$. It takes seven days to get the umbo stage with the mean shell length of $190\mu$ and twenty days to get the morphosing stage with the mean shell length of $260\mu$. The larvae were cultured to the metamorphosing stage with the shell length of $270\mu$ in the laboratory condition.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.4
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• pp.245-251
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• 2019

Sonar bearing accuracy is the correspondence between the target orientation predicted by sonar and actual target orientation, and is obtained from measurements. However, when measuring sonar bearing accuracy, many errors are included in the results because they are made at sea, where complex and diverse environmental factors are applied. In particular, parallax error caused by the difference between the position of the GPS receiver and the sonar sensor, and the time delay error generated between the speed of underwater sound waves and the speed of electromagnetic waves in the air have a great influence on the accuracy. Correcting these parallax errors and time delay errors without an automated tool is a laborious task. Therefore, in this study, we propose a sonar bearing accuracy measurement equipment with parallax error and time delay error correction. The tests were carried out through simulation data and real data. As a result of the test it was confirmed that the parallax error and time delay error were systematically corrected so that 51.7% for simulation data and more than 18.5% for real data. The proposed method is expected to improve the efficiency and accuracy of sonar system detection performance verification in the future.

• Journal of Aquaculture
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• v.10 no.2
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• pp.113-121
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• 1997

In order to developed the techniques for artificial seedling production of geoduck clam, Panope japonica, various stimulution for spawning induction and hatching condition were studied. Spawning induction by the air day or UV-irradiation stimulus were not effective. Water temperature stimulus was responsed 15.0~25.0% in May and 10.0% in June. But spawning induction by the gonad incision was highest with 15.0~45.0%. Ammonium hydroxide (NH4OH) stimulus adding in seawater were responsed 15.0% at 8/1000N~10/1000N, and ammonium hyhroxide solution injected in the gonads were responsed 5.0~10.0% at 5/100N~7/100N. The highest fertilization and hatching rate at various water temperature were ranged 74.5~89.2% in 11~$17^{\circ}C, \;84.3~89.5%\;in\;8~14^{\circ}C$, respectively. the highest fertilization rate and hatching rate in various salinity were ranged 72.5~88.5% in 25~$35tetperthousand$, 82.7~86.9% in 30~$35tetperthousand$, respectively. The optimum water temperature and salinity for fertilization and hatching to the 11~14$^{\circ}C$ and 30~$35tetperthousand$, respectively.

• Journal of Korea Water Resources Association
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• v.30 no.2
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• pp.165-175
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• 1997

This is to study the characteristics of available water resources (AWR) of the eastern coastal area in Korea. A rating curve was suggested at Yangyang water level station of the Yangyangnamdai river. Annual mean precipitation of this area is 1365.8mm. Annual mean precipitation in central and northern area of eastern coastal area is more than that of southern area because of orographic precipitation occurred by the north-easterly air flow from the East sea. By the correlation analysis of monthly rainfall depths between rainfall gauging stations it is presented that the rainfall gauging stations located in coastal region have the regional representativity, but the rainfall gauging stations located in the westward of mountains have a strong locality. AWR of eastern coastal area by the application of runoff coefficient 0.665 is 1134.5X106m3 and 28.6 percentage for total water resources. In each watershed AWR is 193.7X106m3 in the Yangyangnamdai river, 109X106m3 in the Kangnungnamdai river, and 146.0X106m3 in the Samcheokosip river. The seasonal changes of 30/3% in summer and 19.1% in water, and those of the AWR to total water resources are 86.3% in winter, 60.1% in spring, 50.1% in autumn, and 25.7% in summer. The results of this study may be used to establish the water resources planning of eastern coastal area.