• The Korean Journal of Malacology
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• v.18 no.1
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• pp.41-52
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• 2002

This study was performed to know the vertical distribution pattern and community structure of intertidal invertebrates at 9 sampling stations near Songacksan area located in Jeju Island from June 2000 to May, 2001. A total of 104 benthic invertebrate species was recorded during the survey period and it was composed of 50 families, 25 orders, 12 classes and 6 phyla. Among them, the most highest species richness was observed in the mollusks comprising 66.3% (69 species) and the next one in the arthropods showing 16.3% (17 species). Species diversity was largely different depending on their vertical distribution, revealing much higher in the lower intertidal zone than in the middle or upper zone, while there were no distinct differences between sampling stations. The dominant species were Nodilittorina exigua, Littorina brevicula, Pollicipes mitella mitella and Nerita japonica in the upper zone, Monodonta neritoides, Lunella coronata coreensis and Nerita japonica in the middle zone and Notoacmea schrenckii, Omphalius nigerimus, Purpura clavigera and Chlorostoma argyrostoma lishckei in the lower zone. The macrobenthic fauna surveyed could be divided into two groups based on their species similarities between sampling stations but their differences were not distinctive.

• The Journal of Fisheries Business Administration
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• v.30 no.2
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• pp.1-23
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• 1999

In the Northeast Asian region fisheries agreements of the past regarding high seas as an agreement area were transformed or new agreements were introduced in order to conform to the EEZ regime. However, the existing joint regulatory zone which “open” status is somewhat similar to the high sea not only disappear, but also two new systems were established. To begin with, parties of the agreement claimed their EEZs to be from the territorial sea baselines to the extent set forth, problem of the fishery access of the other party under the agreement is to be solved on the principle of reciprocity and on recognizing of the catch results achieved in the past. In regards to the overlapping zones like neutral zone of the East Sea of Korea(Sea of Japan) and neutral zone to the south of the Cheju Island, provisional measures zones in the Yellow Sea and in the East China Sea, and transitional zone of the Yellow Sea special fisheries management systems reflecting the legal character of the zone involved are applied. Moreover, as fisheries agreements defining open sea as an agreement zone are not able to conform to the EEZ regime, so new fisheries agreements must be taken out from old systems and conceptions, and must be understood and enforced from the new point view. Therefore, countermeasures needed to do so should be developed, and their basic structure is as follows. Firstly, the basic concept of the EEZ regime requires that the coastal states have sovereign rights on their sea zones' natural resources and bear responsibilities appropriate to their allowed jurisdiction. Each Northeast Asian state should adjust the structure of fishing industries and employ advanced fisheries management system, and should make efforts toward such issues of the state policy as increasing fishery resources and preserving ocean environment. Secondly, measures should be developed to solve the international fisheries disputes which are to occur under enforcement of the new fisheries agreements system. In regards to the acts of violation the fisheries laws in the foreign EEZ the principle of jail sentence prohibition is established by the UN Convention on the Law of the Sea, and every fisheries agreement reflects this principle. Therefore, the present question is to consider concrete measures to enable the easy release of the seamen, who violated fisheries laws slightly and well-intently, through establishment and management of the guarantee fund needed to make collateral reasonable. Thirdly, Korean-Russian and Russian-Japanese fisheries relations were formed on the basis of the EEZ regime, since 1992 and 1977 respectively, and are expected to maintain mutually beneficial cooperative character. As for Korean-Chinese-Japanese fisheries relations, the operational problems of overlapping zones, and problem of the permits for EEZ mutual access should be solved on the basis of the principle of reciprocity and equity rather than unilaterally from any side.

• Transactions of Materials Processing
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• v.6 no.5
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• pp.446-455
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• 1997

A Combined extrusion operation consists of forward and backward extrusion forming and it is possible to make the process be simple by employing it. But the metal flow pattern induced by the operation is hard to analyze accurately because the flows are non-steady, which have at least two directions dependent upon each other. So engineers in the industrial factories had conducted the two extrusion operations separately. A new process was designed by the industrial expert for forming of an alu-minum preform using the combined extrusion operation. In this study, experiments and finite element analysis was carried out to determine the process parameters. Through the preliminary experiment, it was shown that warm forming condition was more desirable than cold or hot ones. And optimal shape of initial billet could be also determined. From the compatibility test, bonde-lube was chosen as the optimal lubricant and 20$0^{\circ}C$ as the material temperature by the inspection of micro-structure. The operation was simulated by the rigid-plastic finite element method to examine the metal flow. Disap-pearing of dead metal zone was observed as the punch fell down and desirable shape was obtained from the one operation. As a result of this study, 7 operations could be reduced and 225% of material saved.

• Computational Structural Engineering
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• v.9 no.2
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• pp.103-113
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• 1996

This paper presents practical notional-load plastic-hinge method for a two-dimensional steel structure design. The proposed method incorporates the refined plastic-hinge concept for spread of plasticity together with a practical notional-load approach. The proposed method can assess realistically both strength and behavior of a structural system and its individual members in a direct manner. As a result, the method can be used for design without tedious separate member capacity checks, including the calculation of K-factor. The strengths predicted by the proposed method are then compared with those predicted by the exact plastic-zone analysis as well as by the conventional LRFD procedure. A good agreement is generally observed. The displacement predictions are compared with the plastic-zone solutions. Analysis and design guidelines in using the proporsed method are given in detail. Analysis and design procedures are recommended. Member sizes determined by the proposed method are compared with those determined by the LRFD method. It is concluded that the procedures are suitable for adoption in practice.

• Journal of Life Science
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• v.10 no.1
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• pp.14-19
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• 2000

Variation at 25 allozyme loci in Korean wateralder (Alnus hirsuta Rupr.) from nine distinct populations was measured to estimate the amount and pattern of genetic diversity and population structure. The mean genetic diversity within population was 0.166. Korean alder populations have slightly high levels of genetic diversity compared to those present in associated temperature-zone species and two Canadian alder species. Among population s genetic differentiation accounted for an significant 9% of the total variation. High gene flow(Nm=2.63) was observed. Analysis of fixation indices, calculated for all polymorphic loci in each population, showed a substantial deficiency of heterozygotes relative to Hardy-Weinberg expectations. The mean GST value A. hirsuta in Korea (GST = 0.087) is similar to those of A. rogosa in Canada (GST = 0.052). These low values of GST in two countries. reflecting little spatial genetic differentiation, may indicate extensive gene flow (via pollen and/or seeds) and/or recent colonization. These factors reduce the effect of geographic isolation of breeding and the chance for genetic divergence. A pattern of increasing is observed with increasing rainfall per year. Regression analysis indicates that 54% (F = 4.67) of the variability observed can be explained by this relationship.

• Applied Microscopy
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• v.46 no.1
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• pp.51-57
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• 2016

The histology and anatomy of the olfactory organ in Luciogobius guttatus was investigated using a light microscopy and scanning electron microscopy. The paired olfactory organs in the dorsal part of the snout are situated in between the upper lip and the eyes. They consist of two nostrils, one anterior and the other posterior openings, and a single olfactory cavity. The anterior nostril, an incurrent opening, forms a short tubular structure from the skin. The posterior nostril, an excurrent opening, forms a circular structure opened to the exterior. The distributional pattern of the sensory epithelium is a continuous type. The sensory epithelium with numerous-motile cilia is made up of receptor cells, supporting cells, basal cells, and mucous cells. In contrast, the non-sensory epithelium is comprised of stratified epithelial cells and two types of mucous cells, acidic and neutral cells. The cilia number of the receptor cell is in range of 3 to 4 units. Such results in L. guttatus may reflect its ecological habit and microhabitat in the tidal zone with a periodic tide.

• Computers and Concrete
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• v.15 no.4
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• pp.589-606
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• 2015

It is well-documented that the major deterioration of coastal RC structures is chloride-induced corrosion. Therefore, regional investigations are necessary for durability based design and evaluation of the proposed service life prdiction models. In this paper, four reinforced concrete jetties exposed to severe marine environment were monitored to assess the long term chloride penetration at 6 months to 96 months. Also, some accelerated durability tests were performed on standard samples in laboratory. As a result, two time-dependent equations are proposed for basic parameters of chloride diffusion into concrete and then the corrosion initiation time is estimated by a developed probabilistic service life model Also, two famous service life prediction models are compared using chloride profiles obtained from structures after about 40 years in the tidal exposure conditions. The results confirm that the influence of concrete quality on diffusion coefficients is related to the concrete pore structure and the time dependence is due to chemical reactions of sea water ions with hydration products which lead a reduction in pore structure. Also, proper attention to the durability properties of concrete may extend the service life of marine structures greater than fifty years, even in harsh environments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.2
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• pp.182-197
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• 1993

Algal community on the subtidal rocky zone of the South Sea of Korea was divided into two or three sequencing zones. The upper subtidal zone was characterized by the wave exposure-tolerant surf wrack(Pachymeniopsis, Gigartina), which formed dense swirling carpet. Its vertical range was from the surface to $3{\sim}5$ meters in depth, and more deeply extended in turbid waters including Sorido, Yokchido, Pijindo, Manjedo. The mid subtidal zone ranging from 5 to 25 meters in depth was characterized by a large brown algal forest (Ecklenia, Sargassum). But it was generally unrecognizable in that turbid waters, in which the vertical limit of vegetation was at most $10{\sim}15$ meters in depth. The low subtidal zone was characterized by a general lack of algal species and was not easily distinguished from the mid or sometimes from the upper zone. There was a distinct difference in abundance of vegetation between turbid waters and clear waters including Munsom, Kwantaldo, Yosodo, Hongdo, Ch'ujado. In turbid waters the vegetation was much poorer because the tubidity caused from the muddy sediment inhibited an algae to settle down and to grow up. On the basis of the phytogeographical methods using UPGMA, the 10 studied islands were classified into two groups, Munsom and the others. This floristic discontinuity between the two groups might be caused from the difference of water temperature.

• Journal of the Korean Geophysical Society
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• v.2 no.3
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• pp.217-224
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• 1999

Although faults can be found by geological surveys, the surface traces of faults are not easily discovered by traditional geological surveys due to alluvia. In and around faults and fracture zones, the electrical resistivity appears to be lower than that of the surroundings due to the content of groundwater and clay minerals. Therefore, electrical resistivity surveys are effective to search buried faults and fracture zones. The dipole-dipole array electrical resistivity surveys, which could show the two dimensional subsurface electrical resistivity structure, were carried out in two areas, Yongdang-ri, Woongsang-eup, Yangsan-si, Kyungsangnam-do and Malbang-ri, Woedong-eup, Kyungju-si, Kyungsangpook-do. The one was next to the Dongrae Fault and the other near the Ulsan Fault was close to the region in which debatable quaternary fault traces had been found recently. From each measured data set, the electrical resistivity cross-section was obtained using the inversion program the reliability of which was analyzed using analytic solutions. A low resistivity zone was found in the inverted cross-section from the Yongdang-ri area survey data, and two low resistivity zones were found in that from the Malbang-ri area survey data. They were almost vertical and were 15∼20 m wide. Accounting the shape and the very low resistivity values of those zones (<100 Ωm)in the inverted section, they were interpreted as fracture zones although they should be proven by trenching. The reliability of the interpretation might be improved by adding some more parallel resistivity survey lines and interpreting the results in 3 and/or adding other geophysical survey.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.2
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• pp.119-131
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• 2015

The purpose of this study was to compare the differences of the ecological attributes in the two types of urban park at Suwon and Goyang city. 'Directly linked park' is forests and rivers in the vicinity, it is capable of re-supply of the species and 'Isolated park' is forests and rivers apart, it is a difficult re-supply of the species. The result of assessment of the ecological attributes in the two types of urban park was analyzed as the percentage of 'Forest zone' was high, but the percentage of 'Area of permeable pavement' and 'Bush area' was low. 'The planting structure' was mostly 1-layer structure(47%) and 'Foreign tree species' is high by half the proportion. 'Age classes' were a 2-3age classes level, and 'Water body' could barely. Thus, ecological attributes degree was very low. In addition, results of investigation whether the difference of ecological attributes degree between the two types of urban park, also statistically analyzed that there is no difference. Therefore, when establishing the composition of the future plans of the city park, to take full account of the ecological situation in the surrounding parkland, and identify the ecological potential with the parkland. Next, it should be designed and planned of the park that fully utilizing the potential of this ecological attributes.