• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.3
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• pp.259-266
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• 2011

To produce cupped oyster sprat consistently, we investigated the efficiency of nine settlement substrates using selective breeding of Pacific oyster Crassostrea gigas, with the goal of popularizing off-bottom culture on the west coast of Korea. We also compared the growth and survival of selectively bred sprat (diploid) with triploid sprat from an off-bottom culture system. Considering, the attachment rate and detachment efficiency, producing cupped oyster in a polypropylene gunny bag proved to be the most effective method. There were no differences in shell growth or total weight between the diploids from selective breeding and triploids from off-bottom culture for 5 months. However, the survival rate was 8 times higher in the diploids than the triploids. Transplanting sprat from selective breeding is one way to restore oyster farms and nurture off-bottom culture along the west coast.

• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.3
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• pp.73-80
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• 1991

In Korea, small-scale reclaimed areas have been suffering from many problems because of the lack of comprehensive developing strategy although considerable investments have been inputed by the public sector since 1970's. For 3 reclaimed sites in Chonnam Province chosen as case study areas, the analysis, the third attempt of widely-spanned studies on areal conditions, concentrated on their living conditions. Its results were as follows : 1. Although rural residents have increased their concern on health and medical services, the public sector can only serve basic and emergent level of them, and therefore, the private sector, which is mostly placed in urban areas and costed much higher than public one, has the dominant share of those services. So, because those costs are a great expense to rural residents, their supplying system should be planned with special reference to lightening the economic burden of them. 2. By the development of locally fitted programs and innovative systems, the rural education should be qualitatively improved to deal successfully with its small scale. That will result in increasing the schooling rate to schools in rural communities, lightening the economic burden of rural residents on education services and finally activating them to contribute the betterment of rural education. 3. Servicing level of water supply, sewerage and garbage disposal in the reclaimed areas has been remaining at the lower order even in other rural areas. In the design of rural water supply, average daily consumption per capita should be changed according to the composition rate of fishing households and variety of the source of water supply. 4. Most of rural residents in the reclaimed areas want to establish the welfare facilites for the infant, youth, aged and public bath However in the long-term basis, the cooperative production and processing facilities should be considered for modernized efficient farming.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.118-127
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• 2011

An IGCC was evaluated as one of the next generation technologies that would be able to substitute for coal-fired power plants. According to "The 4th Basic Plan of Long-term Electricity Supply & Demand" which is developed by the Electricity Business Acts, the first IGCC will be operated at 2015. Like other new and renewable energy such as solar PV, Fuel cell, The IGCC is considered as non-competitive generation technology because it is not maturity technology. Before the commercial operation of an IGCC in our electricity market, its economic feasibility under the Korean electricity market, which is cost-based trading system, is studied to find out institutional support system. The results of feasibility summarized that under the current electricity trading system, if the IGCC is considered like a conventional plant such as nuclear or coal-fired power plants, it will not be expected that its investment will be recouped within life-time. The reason is that the availability of an IGCC will plummet since 2016 when several nuclear and coal-fired power plants will be constructed additionally. To ensure the reasonable return on investment (NPV>0 IRR>Discount rate), the availability of IGCC should be higher than 77%. To do so, the current electricity trading system is amended that the IGCC generator must be considered as renewable generators to set up Price Setting Schedule and it should be considered as pick load generators, not Genco's coal fired-generators, in the Settlement Payment.

• Journal of Aquaculture
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• v.12 no.1
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• pp.39-45
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• 1999

In order to obtain the basic biological data for artificial seedling production of sea cucumber, Stichopus japonicus, the influence of water temperature and air dry for spawning induction, egg development and larvae rearing was investigated during the period from April, 1995 through September, 1995. Spawning induction rate by the water temperature was 6.0~17.5% and air dry was responsed 1.4~4.0%. Number of eggs spawned of Stichopus japonicus were $50~500\times10^4$ individuals, the fertilization and hatching rate were ranged 84.0~96.0%, 71.4~84.6% respectively. The fertilized egg of Stichopus japonicus appeared mean diameter of $154{\mu}m$. At a constant water temperature of $23^{circ)C$, it become 4 tell stage from fertilization after 2 hours 10 minutes, hatching larvae after 14 hours half, auricularia larvae after 3 days, doliolaria larvare after 11 days and pentactula larvae after 15 days ready for settlement. The suitable food in the larvae reared for 17 days after fertilization were shown the best growth and survival in the larvae food of Chaetoceros calcitrans. Optimum density for larvae rearing were maintained of the larval density lower than 2 individuals/ml.

• The Journal of Fisheries Business Administration
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• v.49 no.4
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• pp.109-129
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• 2018

This study is to evaluate economic effect of the creation project of Octopus Ochellatu spawning and habitat ground in Taean County. The main results of this study are summarized as follows: first, the creation project cost of Octopus Ochellatus spawning and habitat ground invested in Taean from 2015 to 2017 was 3,400 million won. Second, The creation project of Octopus Ochellatus spawning and habitat ground directly provides fishing benefits, recreational boat fishing benefits, festival benefits, research and development benefits, and employment benefits. Third, on the basis of above benefits, the creation project of Octopus Ochellatus spawning and habitat ground has a net present value of 14,478 million won, internal rate of return 60.8%, and benefit-cost of 5.03 under a 4.5% social discount rate. Also, the creation project creates 47 jobs. This indicates that the creation project of Octopus Ochellatus spawning and habitat ground contributes not only to the increase in the income of coastal fishery, recreational boat fishing business and fishing villages but also to the job making. In conclusion, with all these results, a project for making spawning grounds and habitats in the specified region gives species more numerically abundant and this gives more profits to fishermen in the coastal area. In addition, this project helps to make attractions to visitors or people who came to those specified regions to participate in events or have recreation, which means it improves profits to that fishing village and improve a settlement condition.

• Journal of the Korean Geotechnical Society
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• v.27 no.9
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• pp.13-24
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• 2011

The renowned Terzaghi's one-dimensional consolidation theory is not applicable to quantification of time-rate settlement for highly deformable soft clays such as dredged soil deposits. To deal with this special condition, a non-linear finite strain consolidation theory should be adopted to predict the settlement of dredged soil deposits including self-weight and surcharge-induced consolidation. It is of importance to determine the zero effective stress void ratio ($e_{00}$), which is the void ratio at effective stress equal to zero, and the relationships of void ratio-effective stress and of void ratio-hydraulic conductivity for characterizing non-linear finite strain consolidation behavior for deformable dredged soil deposits. The zero effective stress void ratio means a transitional status from sedimentation to self-weight consolidation of dredged soils. In this paper, laboratory procedures and equipments are introduced to measure such key parameters in the non-linear finite strain consolidation analysis. In addition, the non-linear finite strain consolidation parameters of the Incheon clay and kaolinite are evaluated with the aid of the proposed methods in this paper, which will be used as input parameters for the non-linear finite strain consolidation analyses being performed in the companion paper.

• The Korean Journal of Malacology
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• v.24 no.3
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• pp.205-214
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• 2008

To evaluate the aquaculture potential of a subtrophic noble scallop, Chlamys nobilis in Korean waters, nursery growth of the species was studied on two remote Jeju coasts, Jigwido and Ongpori. The early growth performance of the first 60 days after settlement was expressed as: $SL=0.1664e^{0.0579x}$ ($r^2=0.924$), where x stands for days after settlement and SL for shell length. The early spats sized 1 mm in average shell length became $4.1{\pm}0.8\;mm$ after a month of nursery culture, thereafter grew to $13.0{\pm}1.9$, $23.1{\pm}3.1$, $30.3{\pm}4.3$, and $33.6{\pm}5.2\;mm$ for consecutive 4 months in Jigwido coastal area. Mean growth gains (mean daily gains in parenthesis) were $76.7{\pm}7.7$ ($165.6{\mu}m$), $73.3{\pm}7.3$ ($154.0{\mu}m$), $69.4{\pm}8.4$ ($140.0{\mu}m$), and $68.7{\pm}8.5\;mm$ ($137.4{\mu}m$), in depths of 5, 10, 15, and 20 m, respectively. The growth rate was significantly decreased as cultured in deeper place (p < 0.05). As culturing density was higher, growth performance of the scallop was decreased in both locations. Overall, in our preliminary study, the growth performance of scallop in Korean waters was not better than that in Japan, but it seems to be worth doing further study for successful introduction to Korean waters.

• Journal of the Korean Society of Safety
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• v.15 no.2
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• pp.111-117
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• 2000

In this study, the bearing capacity behavior of strip footing located above a continuous cavity in sand was investigated experimentally. The model footing test was performed in a model box made by using raining method in sand. The model footing test results were compared with those obtained from theoretically proposed equations. The results of the analysis indicate that there is a critical region under the footing. For strip footing, there exists a critical depth below which the presence of the cavity has negligible influence on the footing performance. Only when the cavity is located within this region will the footing performance be significantly affected by the presence of the cavity. The size of the critical region depends on several factors such as footing shape, soil property, cavity size and cavity shape. When the cavity is located within the critical region, the bearing capacity of the footing varies with various factors, such as the size and location of the cavity and the depth of foundation. Based on the experimental study, the following conclusions were induced. 1. The ultimate bearing capacity due to the eccentricity of a underground cavity increases at the rate of the small rather than that due to the depth of a underground cavity. This indicates that the bearing capacity of a strip footing is influenced on the depth rather than the eccentricity of a underground cavity. 2. The critical $depth(D/B)_{cr}$, by underground cavity in sand soil ground that is made by the relative density($D_r$)=55%, 65%, 75%, approaches a range of about 8~10 in case of W/B=1, and about 11~13 in case of W/B=2. 3. In case of the relative density($D_r$) 75%, the most outstanding differential settlement trend is shown in the depth of 4~8cm regardless of the size of cavity, namely, when the value of D/B is 1~2. Therefore, a underground cavity influences on not only the decrease of the bearing capacity but also the differential settlement of a strip footing.

• Journal of the Korean GEO-environmental Society
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• v.10 no.5
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• pp.19-26
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• 2009

Rammed Aggregate Pier (RAP) method is intermediate foundation between deep and shallow foundation, and it has been built in world wide. RAP represents a relatively new method that has grown steadily over 19 years since Geopier of USA developed this revolutionary method in 1989. The investigation and research in domestic is not accomplished. In this paper, the examined details of different spacing of piles, bearing capacities, respectively, conclude with recommendations on how RAP can be used in future needs. This documentation further provides comparisons of the laboratory test results which were obtained from changing the spacing of piles, namely installed rammed aggregate pier. Laboratory model test was administered in a sand box. Strain control test was conducted to determine the bearing capacities of the piers; 20 mm, 30 mm and 40 mm RAP in diameter using drilling equipment to make holes were installed in sand at initial relative densities of 40%. By comparing different spacing of piles, in this experiment, piles are spaced structually span, form a ring shape, narrowing the distance of each other, to the center. the result shows that as diameter of pier is bigger in diameter, bearing capacity also dramatically increased due to raised stiffness. Also, as the space between each piers was closed, the settlement rate of soil was decreased significantly. From the test results, as the space between each piles were getting closer, it allows greater chances to have more resistance to deformation, and shows more improved stability of structures. After from the verification work which is continuous leads the accumulation of the site measuring data which is various, and bearing capacity and the settlement is a plan where the research will be advanced for optimum installed RAP.

• Journal of the Korean Geotechnical Society
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• v.20 no.3
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• pp.107-117
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• 2004

This paper is to investigate the reinforcing effects of newly devised Tire-cell mat made of waste tires in sand. Parametric study on number of connection bolts between Tirecells, relative density of sand, embedded depth, number of reinforced layers and width of Tirecell mat was made by using plate loading tests. It is found that the number of connection bolt was enough to maintain the given pressure. The bearing capacity ratio(BCR), which is defined as the rate of ultimate bearing capacity of reinforced soil to that of unreinforced soil, is the highest at the lowest density. And the reinforcing effect can be obtained in case of embedded depth within 1.0B, where B is loading width. Also settlement reduction is the highest at the lowest density of sand. The effect of number of Tirecell reinforced layers with 0.4B to 0.5B interval is limited to 2 layers and further reinforcing effects can not be obtained beyond 3 layers. Especially, the bearing capacity increased remarkably at 1 layer of reinforcement and the degree of increase was small from 1 layer to 2 layers of reinforcement. The effect of mat width of Tirecell was not significant because of high stiffness of Tirecell although the maximum bearing capacity was shown at the 2.0B mat width and the reinforcing effects of Tirecell, in general, was prominent compared with those of commercial Geoweb.