• Journal of the Korean Society for Nondestructive Testing
• /
• v.28 no.5
• /
• pp.401-406
• /
• 2008

Recently, portable magnetic sensors with high sensitivity are strongly required for various applications such as biosensor, nondestructive testing and directional sensor. A novel magnetic sensor system was developed by utilizing giant magnetoimpedance(MI) effect of soft magnetic ribbons. The sensor system consists of sensing head of $Co_{66}Fe_{4}Si_{15}B_{15}$ ribbon having asymmetric MI characteristics through exchange coupling produced by field-annealing in open air and circuit for signal processing. The sensor system showed almost linear characteristics in dynamic range of $-1\;Oe\;{\sim}\;1\;Oe$ and sensitivity of 10.5 V/Oe. The sensor was applicable to nondestructive testing system to detect defects in wire ropes.

• ALGAE
• /
• v.33 no.1
• /
• pp.101-108
• /
• 2018

Saccharina japonica was introduced to both Korea and China from Hokkaido, Japan, and it has become an economically important species in both nations. After a long period of cultivation, several varieties of S. japonica have been developed in Korea and China. In this study, we conducted aquacultural research on the persistence of thalli from two kelp cultivars, one from China (Huangguan No. 1) and one from Korea (Sugwawon No. 301), between December 2015 and November 2016 in Haenam, Korea. The maximum length was $247.8{\pm}13.0$ and $227.5{\pm}42.0cm$, respectively, which were significantly longer in Sugwawon No. 301 than in Huangguan No. 1. The maximum width was $29.9{\pm}5.4$ and $23.2{\pm}1.9cm$, respectively, which were significantly wider in Huangguan No. 1 than in Sugwawon No. 301. The mean biomass obtained from the culture ropes was for Sugwawon No. 301 was $3.5{\pm}0.3kg\;wet\;wt\;m^{-1}$ and for while Huangguan No. 1 was $3.1{\pm}1.0kg\;wet\;wt\;m^{-1}$ of culture rope. After August, the persistence of the thalli of Sugwawon No. 301 was two months longer than that of Huangguan No. 1. We found that the Sugwawon No. 301 performed as well as the Huangguan No. 1 in Korean waters possibly due to increased flexibility as a result of the different cell arrangements of the two cultivars. Overall, the use of the Sugwawon No. 301 cultivar rather than the Huangguan No. 1 cultivar of S. japonica appears the best alternative to help to ensure a stable year round algal feed supply for the Korean abalone industry.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.32 no.1
• /
• pp.7-15
• /
• 1996

Full scale experiment was carried out in the southern sea of Korea to compare some important factors tested in the model experiment. The results obtained can be summarized as follows ; 1. The changing aspect of mouth performance of the full scale net was almost coincided with the results obtained by the model experiment. The vertical opening(H) and the opening area(S) can be expressed as a function of the towing velocity(V) as H=48.78. $e^0.38V$(unit: m, k't) S= 1,443 .$e^-0.25V$(unit: $m^2V$, k't) 2. The changing aspect of working depth of the full scale net was almost coincided with the results obtained by the model experiment. The depth(D) can be expressed as a function of the towing velocity(V) and the warp length(L) as D=92.49.$V^1.37$(unit: m, k't, L= 150m) D= 12.07+0.32. L (unit: m, V=2k't) [)= - 7.90+0.22 . L (unit: m, V=3k't) 3. Some problems were found to operate A - type full scale net by common bottom pair trawlers. The problems can be summarized as follows; (1) Entangling of wing and square head ropes while net casting.(2) Man power needed and time spent for net hauling by common bottom trawlers increased considerably.( 3) Tearing of nettings caused by over -load of tension and entangling of net pendant while net hauling. To solve these problems, the trawlers are favorable to be equipped with variable pitch propeller and llet drum. While the net is favorable to be constructed with trifurcated net pendant in stead of quadrifurcated net pendant used at present.

• Journal of the Korean Society of Safety
• /
• v.13 no.4
• /
• pp.221-229
• /
• 1998

This study, with a view point to prevent accidents arising from steel structure, construction process, has taken an approach of reviewing related materials and construction safety guidelines, conducting questionnaire surveys and on field surveys. This study has also analyzed and classified accident cases and disclosed elements concerned with those accidents. A comparative analysis of the disclosed elements against the statutory provisions regarding industrial safety and it showed that strict observance of safety rules of the accident prevention measures in industrial safety standards will result in a decrease in accidents. It is concluded, however, that additional accident prevention measures, as suggested below, should be implemented for performing of more practical and positive accident prevention. 1) Thorough review and preparation at pre-working stage at sites : Such elements of fall preventing facilely as supporting ropes and steel fabrications for safety guard rails should be initially reflected on detailed drawings and shop drawings so that they can be installed in advance at fabricating plants. 2) Sets of steel frame stairs for work platform should be installed or secured with priority and temporary installation of such prefabricated platform as scaffolds should be installed in advance with those platform attached to the frame members on the ground whenever possible before they are lifted. 3) A decrease in the rate of accident by more than 10% on Tuesdays and Thursdays, has been shown from the accident analysis so schedule of construction process should consider possible weekday of high risk of accidents such as Tuesday and Thursday. 4) An array of systemized safety activities should be adopted, such as legal installation of safety facilities based on advance safety management plan, maintenance of safety for machinery and construction equipment, and strict compliance of safety rules by workers.

• Journal of Environmental Health Sciences
• /
• v.29 no.2
• /
• pp.7-15
• /
• 2003

Di-2-ethylhexyl phthalate (DEHP), is a widely used plasticizer known to be a suspected endocrine disrupter, but its exact effects on aquatic organisms are not yet known. When Japanese medaka (Oryzias latipes) were exposed from the time of hatching to 3 months of age to an aqueous DEHP solution at nominal concentrations of 1, 10, and 50 $\mu\textrm{g}$/l, DEHP treated female fish showed distinct reproductive effect. And the midge (Chironomus riparius.). an aquatic invertebrate, was exposed to DEHP to evaluate the effects on reproductive processes via sediment toxicity. The test endpoints included emergence, sex ratio, fecundity, and the viability of F1 offspring egg ropes. The result implied that the normal developmental and/or reproductive processes in C. riparius had been disrupted when exposed to DEHP, the effect also being displayed in the next generation. In summary, DEHP hinders the development of reproductive organs in the female Japanese medaka and C. riparius.

• ALGAE
• /
• v.27 no.3
• /
• pp.189-196
• /
• 2012

Twelve morphological characters and the biochemical composition of Undaria pinnatifida f. distans sporophytes growing on the rocky shores of Jindo and Wando and on cultivation ropes in Kijang were measured to determine whether each population could be characterized by morphological features and biochemical composition. The goal of this study was to compare phenotypic variations between populations as they relate to environmental conditions. The sporophytes of the Kijang population were two times longer and 19 times heavier than those at Jindo. Sporophylls of the Jindo U. pinnatifida population were significantly smaller in length, width, frill number, and weight than those at Wando and Kijang. Kijang Undaria plants showed the highest contents of total protein, crude fiber, total amino acids, the amount of essential amino acids, the proportion of total unsaturated fatty acids, and eicosapentaenoic acid. However, the Jindo population showed the greatest content of carbohydrates, lipids, and minerals (Zn and Ca) of the three U. pinnatifida populations. In particular, Zn content of Jindo plants was 30 times greater than that of Kijang plants. Thus, the proximate composition, mineral composition, amino acids, and fatty acids of Undaria pinnatifida plants were distinguishable among the three representative Undaria populations evaluated. These results suggest that morphological and biochemical differences of the three U. pinnatifida populations can be attributed to differences in environmental conditions of their habitats.

• Smart Structures and Systems
• /
• v.26 no.1
• /
• pp.89-102
• /
• 2020

Shape memory alloy (SMA)-based Superelasticity-assisted Slider (SSS) is proposed as an engineering solution to practically exploit the well-accepted advantages of both sliding isolation and SMA-based recentering. Self-centering capability in SSS is provided by austenitic SMA cables (or wire ropes), recently attracting a lot of interest and attention in earthquake engineering and seismic isolation. The cables are arranged in various novel and conventional configurations to make SSS versatile for aseismic design and retrofit of structures. All the configurations are detailed with thorough technical drawings. It is shown that SSS is applicable without the need for Isolation Units (IUs). IUs, at the same time, are devised for industrialized applications. The proof-of-concept study is carried out through the examination of mechanical behavior in all the alternative configurations. Force-displacement relations are determined. Isolation capabilities are predicted based on the decreases in seismic demands, estimated by the increases in effective periods and equivalent damping ratios. Restoring forces normalized relative to resisting forces are assessed as the criteria for self-centering capabilities. Lengths of SMA cables required in each configuration are calculated to assess the cost and practicality. Practical implementation is realized by setting up a small-scale IU. The effectiveness of SSS under seismic actions is evaluated using an innovative computer model and compared to those of well-known Isolation Systems (ISs) protecting a reference building. Comparisons show that SSS seems to be an effective IS and suitable for earthquake protection of both structural and non-structural elements. Further research aimed at additional validation of the system are outlined.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.4
• /
• pp.501-509
• /
• 2010

A floating crane is a crane-mounted ship and is used to assemble or to transport heavy blocks in shipyards. In this paper, the static and dynamic response of a floating crane and a heavy block that are connected using elastic booms and wire ropes are described. The static and dynamic equations of surge, pitch, and heave for the system are derived on the basis of flexible multibody system dynamics. The equations of motion are fully coupled and highly nonlinear since they involve nonlinear mass matrices, elastic stiffness matrices, quadratic velocity vectors, and generalized external forces. A floating frame of reference and nodal coordinates are employed to model the boom as a flexible body. The nonlinear hydrostatic force, linear hydrodynamic force, wire-rope force, and mooring force are considered as the external forces. For numerical analysis, the Hilber-Hughes-Taylor method for implicit integration is used. The dynamic responses of the cargo are analyzed with respect to the results obtained by static and numerical analyses.

• Journal of Korean Society of Forest Science
• /
• v.40 no.1
• /
• pp.57-62
• /
• 1978

This study was carried out to determine the proper transplanting time of Platanus occidentalis L. (plane tree, sycamore) with 5 to 6 cm and 25 to 30 cm in diameter of breast height at the forest nursery of Chonnam National University in 1977. For that purpose, the experiment of the time of transplantation, and the moisture content and soluble sugar were analysed. The results are as follows: 1. Both its rooting and growth were slightly different in the period of January to early April (before bud-break), but remarkably declined after its bud-break (mid-April to May). 2. And also, its moisture content and soluble sugar were slightly different (January to early April), but, on the other hand, considerably increased in the content of moisture and sharply decreased in soluble sugar after bud-break (mid-April to May). 3. In comparision with healthy trees, rooting and growth of trees infected with Cankers were unusually retarded and its moisture content and soluble sugar were much less. 4. The proper time to plant sycamore was recognized to be the period of November to March, since the higher amounts of soluble sugar and the lesser amounts of moisture in that period. 5. The sudden exposure to the sun of the boles of diseased and wounded trees could be in death in case of sun-scald on the side of south-west. 6. Pruning wounds should be treated with an antiseptic, as soon as they are made, to prevent entrance of decay or disease while the wound is healing. 7. The wound and sun-scald can be presented by covering the trunk with straw ropes before transplantations.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.46 no.4
• /
• pp.441-448
• /
• 2010

This paper was concentrated on the distribution and the composition of lost fishing gear on the sea bed around yellow croaker fishing ground in the near sea of Jeju, Korea from April to October 2009 in order to improve the fishery environment. Recovering lost fishing gears was carried out total 10 times with a trawlnet along the isobath. As the result, it seems reasonable to conclude that the amount of lost fishing gear has a deep connection with the dip of the sea bed as well as the fishing gear scale, fishing ground and so on. The amount of recovered lost fishing gears were in order of gillnets, dragged gears, traps and ropes. In particular, traps were recovered almost every time within the survey area.