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        검색결과 15

        1.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study is to investigate the response reducing effect of a seismic isolation system installed between 300m dome and supports under both horizontal and vertical seismic ground motion. The time history analysis is performed to investigate the dynamic behavior of single layer lattice domes with and without a lead rubber bearing seismic isolation system. In order to ensure the seismic performance of lattice domes against strong earthquakes, it is important to investigate the mechanical characteristics of dynamic response. Horizontal and vertical seismic ground motions cause a large asymmetric vertical response of large span domes. One of the most effective methods to reduce the dynamic response is to install a seismic isolation system for observing seismic ground motion at the base of the dome. This paper discusses the dynamic response characteristics of 300m single layer lattice domes supported on a lead rubber seismic isolation device under horizontal and vertical seismic ground motions.
        4,300원
        3.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As the national income grows, there is a growing demand for buildings that require long span structures such as exhibition facilities, sports facilities, special industrial facilities, and aerospace facilities. Single-layer latticed dome is one of representative llong span structures. But single layer latticed domes are apt to occur the unstable phenomena that are called “buckling” because of the lack of strength of members and instability of structures, etc. In the previous study, the structural stability of a single-layer lattice dome was roughly grasped by a frame structural system using a ready-made steel when a self-weight and a snow load were applied to a single-layer latticed dome having a span of 300 m and a height of 75 m. However, a systematic study of a 300m single layer lattice dome with various rise-span ratios was not performed. Therefore, it is necessary to study various conditions of this structure because the researchers do not have much research data to apply to actual design. Therefore, the purpose of this study is to verify the buckling characteristics of span 300M single-layer latticed dome with rise-span ratio
        4,000원
        4.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In recent years, single layer latticed domes have attracted many designers and researchers’s attention all over the world, because single layer latticed domes as space structure are of great advantage in not only mechanical rationality but also function, fabrication, construction and economic aspect. Yamada developed the shape factor S which represents the shape of spherical latticed dome from a structural perspective as well as a geometric perspective. According to a prior study, the structural behavior and the buckling characteristics of the latticed dome were mostly noticeable when the shape factor of latticed dome was in the range of 1.5 to 5. That is, S, in the range of 1.5 to 5, are able to estimate not only overall buckling, but also member buckling and nodal buckling. In this study, we developed shape models using various size of members with the fixed rise-span ratio. One particular characteristic of the latticed dome is that it is not only light in weight but also high in strength. But the aiming at the use of light-weight materials and at the minimized section of members may result in buckling to cause an unstable state of the overall structure when the external force reaches a limitation. Especially, the structural strength is disadvantageous to the snow loads than the earthquake loads because of light-weight, and is greatly affected by the conditions of loading. This paper is to develop the structural stability according to the shapes and load conditions for single-layer latticed spherical dome with 300m span.
        4,000원
        5.
        2015.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently two seismic cloaking methods of earthquake engineering have been suggested. One is the seismic wave deflection method that makes the seismic wave bend away and the other is the shadow zone method that makes an area that seismic waves cannot pass through. It is called as seismic cloaking. The fundamental principles of the seismic cloaking by variable refractive index were explained. A two-dimensional cylindrical model which was composed of 40 layers of different density and modulus was tested by numerical simulation. The center region of the model to be protected is called ‘cloaked area’ and the outer region of it to deflect the incoming wave is called ‘cloaking area’ or ‘cloak area.’ As the incoming surface wave is approaching to the cloaking area, the refractive index is decreasing and, therefore, the velocity and impedance are increasing. Then, the wave bends away the cloaked area instead of passing it. Three cases are tested depending on the comparison between the seismic wavelength and the diameter of the cloaked region. The advantage and disadvantage of the method were compared with conventional earthquake engineering method. Some practical requirements for realization in fields were discussed.
        4,000원
        6.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated the embedded depth of guardrail posts through 3-D soil material model and carried out evaluation of the dynamic performance of guard rail. In order to calculate for embedded depth of sloping ground, displacement of guardrail posts is analyzed according to the embedded depth of experiment variables. Through the static test of guardrail posts, the maximum deflection was found to decrease the interval. By performing the dynamic test using the Bogie Car, that is confirmed the elastic modulus of the soil occuring the maximum deflection. Guardrail posts is considered to need for further reinforcement in the larger slope than the plains. This study researched about maximum displacement and deviation velocity through dynamic performance of guardrail system and conducted analysis about protection performance evaluation of passenger.
        4,000원
        7.
        2012.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : In This study two different concrete barrier systems have been proposed to be established at the small vehicle driveway. One is for median barrier, and the other is for roadside barrier. METHODS : In order to determine the suitable shape of barrier, the impact parameters including vehicle weight, impact angle, impact velocity and impact level have been analyzed. The real crash test has been carried out with 0.9 ton and 2.5 ton vehicles, respectively by using the 2m segment type concrete barriers connected by steel plates that are totally 40m barrier systems. RESULTS : The numerical results obtained by LS/DYNA-3D software are compared with real crash tests from the viewpoints of vehicle stability, vehicle trajectory, occupant risk, etc. CONCLUSIONS : From the above results, the dynamic performance of proposed barrier systems satisfies the specification of Korean Code for roadside safety structures.
        4,300원
        8.
        2012.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Korean large purse seine fishery catches chub mackerel, sardine, jack mackerel, Spanish mackerel, etc. which are mainly pelagic fish species. The proportion of chub mackerel was 60% over in Korean large purse seine fishery. Sea surface temperature (SST) increased 0.0253℃ per year and total rising rate was 0.759℃ from 1980 to 2009 in the southern sea of Korea, where is mainly fishing grounds of Korean large purse seine. It was that p〈0.01 level was statistically significant. It is northward movement that the center of fishing grounds of chub mackerel by Korean large purse seine fishery moved 4.57km/yr. It was rapidly northward movement about 7.1km/yr, 8.13km/yr to move Spanish mackerel and bluefin tuna fishing grounds. However, the fishing grounds of jack mackerel were moved further south in the 2000s than the 1980s. Catch of tunas and bluefin tuna consistently increased in Korean waters. There was a significantly positive correlation between SST and catch of bluefin tuna in the fishing grounds of Korean waters.
        4,200원
        9.
        2011.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A preliminary study on species composition of a Korean purse seine catch landed at cannery was conducted in April 2011. In the cannery, all tuna catch are sliding through a sorting grid panel that filters and drops fish in the buckets by size class (above 9kg, 3.4-9kg, 1.8-3.4kg, 1.4-1.8kg and below 1.4kg). In cannery processing, species sorting was made for skipjack tuna and yellowfin tuna only from catches greater than 3.4kg during filtering but not for bigeye tuna because of difficulties in species identification between bigeye tuna and yellowfin tuna under frozen state. As no species identification was carried out for catch groups less than 3.4kg in the cannery process, this study focused on sorting out skipjack tuna and yellowfin tuna from these groups and then identifying bigeye tuna from all size groups of yellowfin tuna. Using the mixture rate of species obtained from the samples taken, species composition of the landed catch was estimated. As results, cannery research showed 95% for skipjack tuna, 3% for yellowfin tuna and 2% for bigeye tuna in species composition, while vessel logbook data represented 96%, 3% and 1% for skipjack tuna, yellowfin tuna and bigeye tuna, respectively. The proportion of bigeye tuna identified in the cannery was slightly higher than shown in logbook data by 1%.
        4,500원
        10.
        2010.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To investigate the catches of jack mackerel fishery, a series of fishing experiments was conducted in the high seas of the southeastern Pacific Ocean (30˚S-38˚S, 82˚W-95˚W) during the period of 9 August to 18 December, 2003 by commercial fishing vessel and research vessel. The number of 205 tows fishing was carried out in the southeastern Pacific Ocean. The total catch was 1,988 ton and CPUE was 2.4 ton/hour. CPUE showed high values in the frontal zone during the survey. Main target species caught from the experimental fishing were the jack mackerel, Trachurus murphyi (98.1%) and chub mackerel, Scomber japonicus (1.9%) as bycatch. Body length of the jack mackerel was different between female and male. The high mean catch per unit effort of jack mackerel was showed when the fishing ground of jack mackerel fishery was over the 110˚W in the southeastern Pacific Ocean. But the fluctuation of the catch per unit effort in the western part of fishing ground was not matched with those year. Reliable physical and oceanographical information will be useful for the efficiency of fishing activity. According to the result of monthly movement of center of fishing ground, the fishing activity of jack mackerel fishery was performed northward in the southeastern Pacific Ocean as time passes.
        4,200원
        11.
        2010.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The population of small yellow croaker, Larimichthys polyactis, in the Yellow and East China Seas has decreased significantly since the mid 1970s. Several management measures have been introduced to conserve it, but population size remains low. To rebuild this population, it is now necessary to consider more effective management methods based on the stock assessment. To determine long-term population changes, fishery and biological data collected over 34 years (1969-2002) were analysed. Yearly fish length compositions were analysed for the time periods 1968 through 1970, 1978 through 1982, and 1993 through 2002; and catch data was available from 1969 to 2002. Annual population sizes were calculated based on length composition, the relationship between total length and body weight, and total landings. Analyses showed that since the 1970s, average size of harvested fish decreased; the proportion of less mature fish (smaller than the 50% maturity length, 19cm) in catches has increased and the estimated biomass has decreased significantly. Consequently, the main management recommendation is that juvenile fish need to be better protected to allow the rebuilding of resources to a more sustainable population level. This will require fish size limit, permissible mesh size, and closed area and season regulations.
        4,600원
        12.
        2010.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Species composition and seasonal variation of fish assemblage in Sacheon marine ranching, Korea were examined. Sampling was seasonally made by a shrimp trawl from February 2009 to November 2009. A total of 55 species were collected. Of these, five species was dominant species comprising 51.1% of the total number of individuals. Nine species represented 57.3% of the total biomass. While total abundance (number of individuals) was high in spring, total biomass and species richness (number of species) and diversity were high in autumn. Cluster analysis, based on seasonally abundance data of the 21 most common species, showed that the species were separated into 4 different groups. Group A composed of Pholis nebulosa, Pleuronectes yokohamae, Hypodytes rubripinnis, Hexagrammos otakii, Tridentiger trigonocephalus and Paracercis sexfasciata, which were year round residents, group B Congr myriaster, Leiognathus nuchalis, and Platycephalus indicus, which were abundant in autumn, group C Sillago japonica, Pseudaesopia japonica, Zoarces gilli, Pholis fangi, and Pleuronichthys cornutus which were abundant in spring, and group D Sillago sihama, Cociella sp., Johnius grypotus, Cynoglossus joyneri, Cynoglossus robustus, and Pennahia argentata, which were abundant in summer. Principal component analysis revealed that seasonal variation in the fish assemblage was attributed to the abundance of temporal species such as conger and sand smelt fishes, which were abundant in summer, due to seasonal variation of water temperature.
        4,200원
        13.
        2009.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Yongdong basin developed during Early Cretaceous in the central part of the Korean Peninsula and bounded on the northwest and southeast by northeast trending mega-scale strike-slip Yongdong Fault. An 8 km thick succession of exclusively terrigeneous sediments can be grouped into two mega-sequences. In concert with the migration of depocenter, the upper sequence overlaps the lower and occupies northern part of the basin during basin evolution. Alluvial and lacustrine environments were predominantly formed from early to late stage of the basin formation. Several lines of evidence support that the basin was formed within intra-arc tectonic environments and destroyed by polyphase tectonic force. Schematic evolutionary diagram of the basin is proposed.
        4,900원
        14.
        1991.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Four novel amphoteric surfactants of N-(2-alkylamidoethyl)-N, N-dimethyl ammonioacetates were synthesized. The each reaction between four saturated fatty acids containing 10, 12, 14 and 16 carbon atoms and N, N-dimethylethylene diamine permitted to give the intermediate products, N-(2-alkylamidoethyl)-N, N-dimethylamines. Quaterinzation of these intermediates was permitted to form N-(2-alkylamidoethyl)-N, N-dimethyl, ammonioacetates, whose sturctures were identified by CC, TLC, elemental analysis, IR pectrophotometry and 1HNMR spectrometry. The products yielded from 48% to 58%. The isoelectric points were shown in the range of 4.30~6.64. It showed a tendency to learn to the acidic site and its range was broadened as increase of the hydrophobic group length. Surface tensions of the aqueous solution in the 10-6~10-1mol/l of amidobetaines were measured. and the critical micell concentration(cmc) were shown in the range of 8.37×10-6~8.96×10-2mol/l, and γcmc were reduced to 32.3~38.2 dyne/cm. A linear relationship between log cmc and the number of carbon in the hydrophobic alkyl chain was presented by the formula of log cmc=2.38-0.5n, and the contribution-rate of n on the standard free energy change in micellization ɘ(δG0m)/ɘn, was calulated as -0.5RT.
        4,000원
        15.
        1989.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Using the quarternary ammonium salts as phase transfer catalyst, the nucleophilic substitution reaction of 1-chlorooctane with sodium-cyanide was investigate kinetically with respect to the formation of octanenitrile. The product was analyzed with gas chromatograph, and quantity of octanenitrile was measured. The reaction condition was considered by the effect of the reaction temperature, of the species and the amount of catalyst, of the speed of strirring, and of the concentration of reactants. The reaction was carried out in the first order on the concentration of 1-chlorooctane and sodium cyanide, respectively. The over-all order was 2nd. The activation energies for the nucleophilic substitution reaction of 1-chlorooctane and 1-bromooctane under tetrabutylammonium hydrogen-sulfate were calculated as 2.05 and 10.08kcal/mol, respectively. The effect of various caltalysts was decreased in the order of tetrabutylammonium bromide, terabutylammonium, tetrabutylammonium hydrogensulfate, and tetrabutylammonium iodide. The reaction rate was dependent on the concentration of sodium-cyanide dissolved in the aqueous phase, and the good result was shown when the mol ratio between 1-chlorooctane and sodium cyanide was one per three.
        4,000원