• The Korean Journal of Malacology
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• v.25 no.2
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• pp.105-112
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• 2009

We investigated the degree of obesity, histological development stages of gonads and sexual maturation induction rates of comb pen shell, Atrina pectinata, per the type of micro-algae supplied. Terms of maturation by singular or mixed supply of microalgae, it was found that maturation of the female was the quickest at 60.0% by the Tetraselmis tetrathele (Tet). experiment group followed by 57.1% by the Chlorella ellipsoidea (Chl). experiment group and 16.7% by the Phaeodactylum tricornutum (Pha). experiment group. However, there were no significant differences between Tet. experiment group and Chl. experiment group. As for the male, maturation was the quickest at 60.0% by the Tet. experiment group followed by 16.7% by the Chl. experiment group and 14.3% by the Pha. experiment group. In light of these results, Tet. is concluded to be a very useful feed organism in breeding the mother comb pen shells. Upon completion of the experiment, the sexual maturation induction rate for the female was found to be the highest at 82.0% in the Tet. experiment group followed by 72.0% by the Chl. experiment group, 64.0% by the Pha. experiment group and 58.0% by the mixed micro-algae experiment group. During the period of experiment, the survival rate was the highest at 94.4% by the mixed micro-algae experiment group followed by 90.0% by the Pha. experiment group, 83.1% by the Tet. experiment group and 78.8% by the Chl. experiment group.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.1
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• pp.45-51
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• 2012

Sea ice properties have been considered a key indicator in the structural design criteria of icebreaking vessels and arctic offshore platforms to estimate design ice load and resistance for their safety management in Arctic Ocean. A measurement study of sea ice properties was conducted during July to August of 2011 with the Korean icebreaking research vessel "Araon" around Chukchi Borderland. The sea ice concentration appears to be rapidly decreasing during this cruise. Ice condition seems to be thick second-year ice and multi-year ice and then, a lot of melt ponds were observed in the surface of ice floe. Calculated flexural strength of sea ice was about 250~550kPa, ice thickness was roughly 1.3~3.0m. In this research we performed field experiment to measure ice temperature along the depth, thickness, density, salinity, brine volume ratio and crystal structure. Apparent conductivities derived with the electromagnetic induction instrument were compared to drill hole measurement results and accuracy of sea ice thickness estimation formula was discussed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.4
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• pp.163-171
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• 1999

In this study, we executed fundamental experiment to investigate properties of accelerated carbonation with changing chloride content of concrete used sea sand in order to examine durability. So we obtained the results of following properties of mechanics, durability, concrete with sea sand, determined concrete w/C 30%, 40%, 50%, and fine aggregate 40% and changing containing chloride 0, 0.3, 0.6, $0.9kg/m^3$ by the experiment of accelerated neutralization. The results of this study as follows: 1) As result of changing chloride content of concrete used sea sand augmented in stages $0.3kg/m^3$, accelerated carbonation was increased as increment chloride content. The increment depth was decreased as it went long term age. It was shown the chloride content effected increment of carbonation depth in concrete 2) As a result of changing W/C of concrete used sea sand augmented in stages 10% at a time from 30% to 50%, accelerated carbonation depth of concrete was increased as W/C ratio. 3) As the carbonation concrete used sea sand, compressive strength between 8 weeks and accelerated carbonation depth of 1 weeks, 2 weeks, 4 weeks, 8 weeks was inversion proportion.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.198-207
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• 2012

In this study, we investigated the effect of ocean fertilization by deep sea water, using an ecosystem model which contains not only phytoplankton but also zooplankton. The model is based on NEMURO which consists of eleven compartments - two species of phytoplankton, three species of zooplankton, $NO_3$, $NH_4$, $Si(OH)_4$, particulate organic nitrogen, dissolved organic nitrogen and particulate silicon. We introduced nitrogen cell quota in the both species of phytoplankton, and silicon cell quota in the large phytoplankton in addition to the eleven compartments of NEMURO. We made the experiment at Izu Oshima Island in order to investigate the effect of ocean fertilization. In this experiment, we could not find clear differences between the cases with and without deep sea water. We investigated the causes of the experiment results by the model simulations. One of the causes was high concentrations of nutrients in surface seawater used in the experiment. Another was that the increase of total concentration of inorganic nitrogen does not necessarily accelerate the photosynthetic rate because inorganic nitrogen uptake rate is related to the ratio of $NO_3$ to $NH_4$. Because the model can represent the results of the experiment, we investigated the effect of ocean fertilization by deep sea water using this model. We found that the effect of ocean fertilization hardly appeared when the interval of the addition of deep sea water was too short, or the amount of deep sea water was too much. It is supposed that if the addition of deep sea water is too frequent or too much, the dilution of plankton's concentrations will exceed the effect of promoting phytoplankton's photosynthesis.

• Journal of Science Education
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• v.38 no.1
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• pp.160-167
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• 2014

A land and sea breeze and the cause of wind are learned through a convection current box experiment in elementary science class. The purpose of this study was to investigate elementary students' perception and inferring process about a land and sea breeze. For this purpose, the 159 elementary students who lived in J city were collected. The results of this study showed that the students who perceived correctly about a land and sea breeze and the cause of wind were only 45 persons(28.3%). And most of the students understood the direction of the wind as they observed in the experiment. That is, most of the students did not understand a direction of a land and sea breeze by a inferring process from the experimental result. They did not pass by a inferring process. These results demand that a new convection current box experimental set is to be developed, as well as the experimental instruction more focused on the inferring process, for the perception of a land and sea breeze and the cause of wind.

• Atmosphere
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• v.32 no.4
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• pp.395-409
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• 2022

A new soil moisture initialization scheme is applied to the Korea Meteorological Administration (KMA) Global Seasonal forecasting system version 6 (GloSea6). It is designed to ingest the microwave soil moisture retrievals from Soil Moisture Active Passive (SMAP) radiometer using the Local Ensemble Transform Kalman Filter (LETKF). In this technical note, we describe the procedure of the newly-adopted initialization scheme, the change of soil moisture states by assimilation, and the forecast skill differences for the surface temperature and precipitation by GloSea6 simulation from two preliminary experiments. Based on a 4-year analysis experiment, the soil moisture from the land-surface model of current operational GloSea6 is found to be drier generally comparing to SMAP observation. LETKF data assimilation shows a tendency toward being wet globally, especially in arid area such as deserts and Tibetan Plateau. Also, it increases soil moisture analysis increments in most soil levels of wetness in land than current operation. The other experiment of GloSea6 forecast with application of the new initialization system for the heat wave case in 2020 summer shows that the memory of soil moisture anomalies obtained by the new initialization system is persistent throughout the entire forecast period of three months. However, averaged forecast improvements are not substantial and mixed over Eurasia during the period of forecast: forecast skill for the precipitation improved slightly but for the surface air temperature rather degraded. Our preliminary results suggest that additional elaborate developments in the soil moisture initialization are still required to improve overall forecast skills.

• Journal of the korean society of oceanography
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• v.39 no.1
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• pp.72-95
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• 2004

The Yellow Sea is characterized by relatively shallow water depth, varying range of tidal action and very complex coastal geometry such as islands, bays, peninsulas, tidal flats, shoals etc. The dynamic system is controlled by tides, regional winds, river discharge, and interaction with the Kuroshio. The circulation, water mass properties and their variability in the Yellow Sea are very complicated and still far from clear understanding. In this study, an effort to improve our understanding the dynamic feature of the Yellow Sea system was conducted using numerical simulation with the ROMS model, applying climatologic forcing such as winds, heat flux and fresh water precipitation. The inter-annual variability of general circulation and thermohaline structure throughout the year has been obtained, which has been compared with observational data sets. The simulated horizontal distribution and vertical cross-sectional structures of temperature and salinity show a good agreement with the observational data indicating significantly the water masses such as Yellow Sea Warm Water, Yellow Sea Bottom Cold Water, Changjiang River Diluted Water and other sporadically observed coastal waters around the Yellow Sea. The tidal effects on circulation and dynamic features such as coastal tidal fronts and coastal mixing are predominant in the Yellow Sea. Hence the tidal effects on those dynamic features are dealt in the accompanying paper (Kim et at., 2004). The ROMS model adopts curvilinear grid with horizontal resolution of 35 km and 20 vertical grid spacing confirming to relatively realistic bottom topography. The model was initialized with the LEVITUS climatologic data and forced by the monthly mean air-sea fluxes of momentum, heat and fresh water derived from COADS. On the open boundaries, climatological temperature and salinity are nudged every 20 days for data assimilation to stabilize the modeling implementation. This study demonstrates a Yellow Sea version of Atlantic Basin experiment conducted by Haidvogel et al. (2000) experiment that the ROMS simulates the dynamic variability of temperature, salinity, and velocity fields in the ocean. However the present study has been improved to deal with the large river system, open boundary nudging process and further with combination of the tidal forcing that is a significant feature in the Yellow Sea.

• The Korean Journal of Malacology
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• v.27 no.4
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• pp.331-336
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• 2011

The present study investigated survival and growth of the abalone, Haliotis discus hannai and sea cucumber, Stichopus japonicus co-cultured and supplied with abalone formula feed (AFF) and dry sea tangle (DST) in indoor tank. During the experimental period from April 20 to July 15 in 2011, we used abalone with shell length of $28.54{\pm}1.23mm$ and total weight of $2.92{\pm}0.26g$. The sea cucumber used in the experiment weighed $3.0{\pm}0.2g$ in wet weight. For the experiment, 3 types of feeds including AFF, DST and AFF-DST mixed (1:1) group were supplied to abalone and sea cucumber. During the experiment, survival of abalone reached over 97.0% and 87.0% for sea cucumber in three experimental tanks. Survival of the abalone was found to be higher in DST group, while it was lower among sea cucumber, although the survival was not significantly different among three experimental group. Growth of abalone fed with AFF was significantly higher, while the growth rate of sea cucumber was highest in the tank fed with AFF+DST mixed diet (P < 0.05).

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.180-185
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• 2001

In order to regulate the physical characteristics of an ocean dumping material in the south-eastern East Sea, the diffusion characteristics with the observation, hydraulic experiment and numerical experiment data are investigated. The main results are as follows; (1) Spying CTD observation result of the area of Jung in the East Sea, the ocean dumping area had influenced the Tsushima warm current of high temperature and salinity. Horizontal turbulent diffusivity is 1.913${\times}$10$^{7}$ $\textrm{cm}^2$/sec by drogue tracking. (2) From the experiment of settling, the initial settling velocity of each material is 1.0∼2.7 cm/sec according to the specific gravity and initial concentration. In the pycnocline, particles didn't settle under the pycnocline any more and accumulated. It is signified that calculation of the sedimentation rate of the ocean dumping material including of vertical diffustion must be regard the pycnocline in the ocean area have well-developed pycnocline. (3) Vertical turbulent diffusivity were 2.219${\times}$10$^{-8}$∼8,874${\times}$10$^{-4}$ $\textrm{cm}^2$/sec from the experiment of settling. And, the pycnocline influenced the vertical turbulent diffusivity. (4) From the result of diffusion simulation in the East Sea, the co-concentration line of 0.05 ppm and 0.1 ppm are limited at dumping area after 200 days. The constant concentration line of 0.01 ppm is distributed to the vicinity of Ulleungdo and Tokdo, but isn't distributed to the coastal area of East Sea and southern area of Jung in the East Sea.

• Korean Journal of Plant Resources
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• v.19 no.6
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• pp.687-691
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• 2006

This experiment was conducted on rice (cv. 2005 Thaoi) seeds to study whether priming with deep sea water (DSW) results in enhancement of seed emergence and seedling growth and to identify the optimum concentration of Deep Sea Water (DSW) for priming. Two experiments were conducted subsequently. In experiment 1, four concentrations of the DSW (10%, 20%, 30% and 40%), and in experiment 2, five concentrations of DSW (10%, 15%, 20%, 25% and 30%) were prepared and seeds were primed for 24 hours duration at $25^{\circ}C$. Beside this, hydro priming with plain water was also included as a control. Experiments were laid out in Completely Randomized Design (CRD) with three replications. Result showed that 20% DSW seed priming treatment had improved the emergence, seedling height, number of roots and root length as compare to other with DSW or without DSW treatments. Beyond 20% DSW priming (i.e. 25%, 30% and 40%) were not suitable for priming the seed. On the basis of seedlings growth parameters; emergence, seedling height, root number and length, and shoot root ratio, 20% DSW priming was the best priming treatment.