• Journal of Korean Society of Steel Construction
• /
• v.18 no.4
• /
• pp.457-468
• /
• 2006

An experimental study was performed to investigate the maximum energy dissipation and the ductility capacity of shear-dominated steel plate walls with thin web plates. Three specimens of three-story plate walls with thin web plates were tested. The parameters for the test specimens were the aspect ratio of the web plate and the shear strength of the column. A concentrically braced frame and a moment-resisting frme were a also tested for comparison. The steel plate walls exhibited much better ductility and energy dissipation capacity than the concentrically braced frame and the moment-resisting frame. The results showed that unlike other structural systems, the sh as well as strength, and can therefore be used as an effective earthquake-resisting system. A method of predicting the energy dissipation capacity of a steel plate wall was proposed.

• Journal of Korean Society of Steel Construction
• /
• v.15 no.4 s.65
• /
• pp.359-368
• /
• 2003

Design and detailing requirements of seismic provisions for Concentrically Braced Frames (CBF) were specified based on the premise that bracing members with large KL/r and low b/t have superior seismic performance. However, relatively few tests have been done to investigate the cyclic behavior of CBF. Therefore, the question lies on whether the compression member of CBF plays as significant a role as what has been typically assumed by design providers. In this paper, existing experimental data were reviewed to quantify the extent of hysteretic energy achieved by bracing members in past compression tests as well as the extent of degradation of the compression force given repeated cycling loading.

• Journal of Korean Society of Steel Construction
• /
• v.24 no.2
• /
• pp.149-161
• /
• 2012

The use of seismic energy-dissipative devices for passive control is increasing exponentially in the recent years for both new and existing buildings. Use of these devices started in and has been somewhat limited to developed countries. One of the current challenges is to promote the use of seismic dampers in earthquake-prone developing countries by lowering the cost of the devices. This paper proposed a new type of seismic damper based on yielding of a cantilever type metallic element for seismic retrofit of existing and new building structures. The hysteretic behavior and energy dissipation capacity of the proposed damper was investigated using component tests under cyclic loads. The experimental results indicated that the damping device had stable restoring force characteristics and a high energy dissipation capacity. Based on these results, a simple hysteretic model for predicting the load-displacement curve of the seismic damper was proposed.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.7 no.6
• /
• pp.93-99
• /
• 2003

In this study, new shock absorbing system is proposed by using nano-technology based on the theoretical analysis. The new shock absorbing system is complementary to the hydraulic damper, having a cylinder-piston-orifice construction. Particularly for new shock absorbing system, the hydraulic oil is replaced by a colloidal suspension, which is composed of a porous matrix and a lyophobic fluid. The matrix of the suspension is consisted of porous micro-grains with a special architecture: they present nano-pores serially connected to micro-cavities. Until now, only experimentally qualitative studies of new shock absorbing system have been performed, but the mechanism of energy dissipation has not been clarified. This paper presents a modeling and theoretical analysis of the new shock absorbing system thermodynamics, nono-flows and energy dissipation. Compared with hydraulic system, the new shock absorbing system behaves more efficiently, which absorb a large amount of mechanical energy, without heating. The theoretical computations agree reasonably well with the experimental results. As a result. the proposed new shock absorbing system was proved to be an effective one, which can replace with the conventional one.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.4
• /
• pp.311-320
• /
• 2003

The coefficient of consolidation of clay deposit is one of the most important properties in the design of ground improvement. The in-situ value of $c_h$ is generally estimated by pore pressure dissipation using piezocone. Many researchers have suggested theoretical formula for its estimation. This study attempts to find out the validity of the existing theoretical formula in Korea and to find out the characteristics of $c_h$ related to the mechanical properties of clay. Piezocone tests and laboratory tests were performed at the site of pilot project of ground improvement at Yangsan-Mulgeum, Gyeongnam. Comparison of the estimated values of $c_h$using piezocone tests results and those from laboratory consolidation tests are carried out. Results show that Torstensson(cylindrical cavity theory) and Teh & Houlsby solutions derive similar values of $c_h$. And $c_h$ from oedometer test shows values similar to the above two methods. The value from either of the above two methods[Torstensson(cylindrical) or Teh & Houlsby] is recommended to be used as $c_h$.

• Journal of Sericultural and Entomological Science
• /
• v.19 no.1
• /
• pp.19-23
• /
• 1977

In the previous short communication, the authors reported the applicability of Sodium Hyplochoride solution to silkworm rearing industry as a disinfectant after confirmed the fact that the chemical agent is capable to kill most of the pathogens of silkworm diseases. The authors, in the present study, attempted to investigate the influence of the chemical on the growth of silkworm larvae and the effect on the disinfection of silkworm larvae to inactivate the pathogen of yellow muscardine disease, Isaria farinosa and the results obtained are summarized as fellows. 1. The chemical agent did not affect the growth of silkworm larvae, when it was applied on silk-worm body with the concentration of 1,3,5 per cent of the agent during the rearing period. 2. The Sodium Hypochloride solution did not give any damage to silkworm larvae when larvae were fed up with 1,3,5 per cent of the solution. 3. In the bioassay of the solution on disinfection of larvae inoculated with yellow muscardine disease pathogen, the fact that the agent could control the disease was observed by showing much low infection rate in 3.5 per cent treatment compared to non-treatment control.

• Journal of the Korean Institute of Gas
• /
• v.15 no.2
• /
• pp.47-56
• /
• 2011

Flame propagation velocity is the one ofmainmechanismof the stabilization of triple flame. To quantify the triple flame propagation velocity, Bilger presents the triple flame propagation velocity depending on the mixture fraction gradient, based on the laminar jet flow theory. However, in spite of these many analyses, there was not presented any relation of these variables, triple flame propagation velocity, radius of flame curvature and scalar dissipation rate indirectly. In the present research, we have checked the results of numerical simulation with experiment and numerical analysis and verified the flame propagation velocity with a scalar dissipation rate proposed by Bilger through the numerical simulation. Also we have clarified that flame propagation velocity was depended on the radius of flame curvature and scalar dissipation rate.

• Journal of Sensor Science and Technology
• /
• v.6 no.5
• /
• pp.356-361
• /
• 1997

Fiber-optic evanescent wave sensor was designed and fabricated to detect mouse immunoglobulin G(IgG) with decladed optical fiber on which anti-mouse IgG was immobilized. A sensitivity obtained by any direct or competitive method was lower than $1\;{\mu}g/m{\ell}$. Anti-mouse IgG was immobilized on 93.9% of core surface of optical fiber by simple adsorption method. The effect of postcoating using bovine serum albumin to remove non-specific binding was not observed. As the ratio of fluorescein to mouse IgG increased, the fluorescence signal increased, but that increase showed no linear relationship. Our fiber-optic sensor system could be used as immunosensor by measuring evanescent fluorescence in antigen-antibody reaction with good sensitivity below $1{\mu}g/m{\ell}$ level.

• Korean Journal of Plant Resources
• /
• v.14 no.3
• /
• pp.259-276
• /
• 2001

Mt. Seoun(574 meters above sea level) is located in the southern part of An-sung city, Korea, within 36$^{\circ}$54'~36$^{\circ}$50'N, 127$^{\circ}$16'~127$^{\circ}$19'E. Field surveys were carried out nine times from March to October, 2000. Main results obtained from this study were as follows. The flora of vascular plants investigated in this survey was 439 taxa belonging to 90 families, 268 genera, 383 species, 49 varieties, 5 forma, 2 hybrid. As a result of this study, rare and endangered(Tricyrtis dilatata Nakai, Gastrodia elata Bl., Saururus chinenses Baill., Viola albida Palibin.) and many endemic species(Athyrium acatipinnulum Kodama., Tricyrtis dilatate Nakai, Paulownia coreana Uyeki., Salix hallaisanensis Lev., Asperula Iasiantha Nakai, Weigela subsessilis L.H. Bailey, Melamdryum seoulense Nakai, Clematis trichotoma Nakai, Spiraea prunifolia var. simpliciflora Nakai, Syringa dilatata Nakai, Chloranthus japonicus var. koreanus Sieb, Scutellaria insignis Nakai) of Korea were distributed in this area. Also the naturalized plants which were appeared in this area were 24 taxa(5.5 %). Among the plant resources, there are 239 taxa of edible plants(54.4%), 270 taxa of medicinal plants(61.5%), 217 taxa of ornamental plants(49.4%), 46 taxa of timber plants(10.5%) and 56 taxa of pasture plants(12.8%).

• Journal of Environmental Impact Assessment
• /
• v.30 no.2
• /
• pp.132-139
• /
• 2021

Laboratory-scale experiments were conducted to assess the effect of oxidative decomposition of polycyclic aromatic hydrocarbons (PAHs) in field soil using peroxy-acid. The study soil texture is sandy soil containing 19.2 % of organic matter at pH 6.8. Among polycyclic aromatic hydrocarbons (PAHs) in the study soil, the concentration of benzo(a)pyrene is 2.23 mg/kg which is three times higherthan the Korea standard level. Therefore benzo(a)pyrene was selected as the target study PAH for the treatment by peroxy-acid oxidation using peroxy-acid coupled with hydrogen peroxide, and the efficiency of the oxidative decomposition of benzo(a)pyrene was assessed for the different organic acids and dosages of an organic acid and hydrogen peroxide. Propionic acid among the tested organic acids showed the highest efficiency of benzo(a)pyrene reduction in the peroxyacid oxidation treatment and finally satisfied the Korea standard level.