• Nuclear Engineering and Technology
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• v.19 no.4
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• pp.292-309
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• 1987

A large dry PWR containment response analysis for postulated severe accidents was performed as part of the Zion Risk Rebaselining study for input to the U.S. NRC's "Reactor Risk Reference Document," NUREG-1150. The Methodologies used in the present work were developed as part of the Severe Accident Risk Reduction Program (SARRP) at Sandia National Laboratory specifically for the Surry Plant, but they were extrapolated to Zion. Major steps of the quantification of risk from a nuclear power plant are first outlined. Then, the methodologies of containment response analysis for severe accidents used for Zion are described in detail: major features of the containment event tree (CET) analysis codes and CET quantification procedures are summarized. In addition, plant specific features important to containment response analysis are presented along with the containment loading and performance issues included in the present uncertainty analysis. Finally, a brief summary of the results of deterministic and statistical containment event tree analysis is presented to provide a perspective on the large dry PWR containment response for postulated severe accidents.accidents.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.2
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• pp.112-127
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• 1997

The purpose of this study is to get optimum operating factors of Upflow Anaerobic Sludge Blanket (UASB) reactor by introducing methods that make it to reduce inhibition possible in each process wastewater treatment. The used substrates, concentrated corn starch liquid (CSL) wastewater, modified starch, filtering and decoloring wastewater, ion refining wastewater, and mixed wastewater including modified starch and not including modified starch, are generated from molasses process. The seeding sludge is the digested sludge that had been applied to molasses wastewater. Batch test to reduce the inhibition factors that might be existed in each wastewater was examined. Based on the this test, the optimum operating factors according to alkalinity and pH variation was studied through the continuous test using three 5.5 L UASB reactor. The first reactor added $NaHCO_3$ to control alkalinity. The hydraulic retention time (HRT) reduced to 8 hours and the organic loading rate increased gradually. The second reactor changed the pH of influent from 7.0 to 6.0 using NaOH. The third reactor was operated without changes to compare the above two reactors. As the result, the inhibition in concentrated CSL wastewater was removed by adding iron (II). When trace metals were added to mixed wastewater not including modified starch, the digestability by gas production rate increased to more fifty percentage than mixed wastewater that was not adding the trace metals. The reason that the inhibition did not decreased in spite of adding trace metals and nutrients was influenced by high concentration generated during the acid fermentation. The UASB reactors using the mixed wastewater with the most effective performance were operated as 500 mg/L as $CaCO_3$ alkalinity and 6.0 pH at steady state, and at this time, the gas production rates were 283 and 311mL gas/g $COD_{added}$. The COD removal rates were 84.7 and 86.3%, respectively.

• Journal of Korean Society of Steel Construction
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• v.29 no.1
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• pp.73-80
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• 2017

In this study, cyclic loading analysis was conducted in order to understand the behavior of self-centering connections based on the number of PT(posttensioning) strands and initial posttensioning force. The initial posttensioning force needs to be above the yield moment of an angle for obtaining noticeable self-centering effect and it is proper that decompression moment ratio needs to be below 0.35 to minimize the residual displacement of major elements. As the number of PT strands increased, self-centering capacity also improved since initial posttensiong force in each PT strand has been decreased. It is also appropriate that initial posttensiong force needs to be less than or equal to 75% of yield strength of PT strands.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.2
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• pp.57-65
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• 2010

To determine the static buckling loads and evaluate the structural performance of slender steel pipe-arches such as for greenhouse structures, a series of modal tests using a fixed hammer and roving sensors was carried out, by providing no load, then a range of vertical loads, on an arch rib in several steps. More attention was given to an internal arch where vertical and horizontal auxiliary members are not placed, unlike an end arch. Modal parameters such as natural frequencies, mode shapes and damping ratios were extracted using more advanced system identification methods such as PolyMAX (Polyreference Least-Squares Complex Frequency Domain), and compared with those predicted by commercial FEA (Finite Element Analysis) software ANSYS for various conditions. A good correlation between them was achieved in an overall sense, however the reduction of natural frequencies due to the existence of preaxial loads was not apparent when the vertical load level was about up to 38% of its resistance. Some difficulties related to the field testing and parameter extraction for a very slender arch, as might arise from the influences of neighboring members, are carefully discussed.

• Journal of Digital Contents Society
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• v.4 no.1
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• pp.45-55
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• 2003

Due to the rapid development of information & communication technology under high performance computing environments, the multimedia production techniques have been applied to a variety of multimedia fields such as general banner advertisements including texts, images and animations, and the internet-broadcasting dealing with videos and sounds. This paper presents an authoring tool with main functions to setup events objects (image, animation, sound, button, area) and to setup action functions, so that non-experts can easily produce multimedia including images, sounds, animations and so on. The authoring tool implemented in Java can be applied to the CD-ROM title production as well as the web-site construction. We can expect that when this authoring tool is used for in multimedia production, both cost and time will be reduced due to its convenience and powerful functions. We have a future plan to integrate intelligent multimedia presentation techniques with the presented tool for the autonomous multimedia authoring works.

• Structural Engineering and Mechanics
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• v.18 no.5
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• pp.645-669
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• 2004

In seismic analysis of moment-resisting frames, beam-column connections are often modeled with rigid joint zones. However, it has been demonstrated that, in ductile reinforced concrete (RC) moment-resisting frames designed based on current codes (to say nothing of older non-ductile frames), the joint zones are in fact not rigid, but rather undergo significant shear deformations that contribute greatly to global drift. Therefore, the "rigid joint" assumption may result in misinterpretation of the global performance characteristics of frames and could consequently lead to miscalculation of strength and ductility demands on constituent frame members. The primary objective of this paper is to propose a rational method for estimating the hysteretic joint shear behavior of RC connections and for incorporating this behavior into frame analysis. The authors tested four RC edge beam-column-slab connection subassemblies subjected to earthquake-type lateral loading; hysteretic joint shear behavior is investigated based on these tests and other laboratory tests reported in the literature. An analytical scheme employing the modified compression field theory (MCFT) is developed to approximate joint shear stress vs. joint shear strain response. A connection model capable of explicitly considering hysteretic joint shear behavior is then formulated for nonlinear structural analysis. In the model, a joint is represented by rigid elements located along the joint edges and nonlinear rotational springs embedded in one of the four hinges linking adjacent rigid elements. The connection model is able to well represent the experimental hysteretic joint shear behavior and overall load-displacement response of connection subassemblies.

• Journal of the Korea Society of Computer and Information
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• v.11 no.6 s.44
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• pp.35-47
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• 2006

In an Ubiquitous Environment, the growth of various services and equipment is forecasted to increase both the multicast users and diverse hacking attacks of the multicast key. Rapid increasing of multicast users and application security protocols reduce the performance of the Central key management system. Accordingly. We propose to elevate the functionality of the key management mechanism for greater efficiency and stability of the multicast services. in this paper The existing key management mechanism comparison and simulation will analyze these problems. We propose the advanced SMKD (Secure Multicast Key Distribution) mechanism application of the small group and key length control new security protocol by methods to solve these problems. The SMKD Model in this paper will help reduce loading the key distribution and encryption execution of a central key management system, and this model can also ensure stability to a central key management system by efficient key management.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.317-326
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• 2011

Today there is a growing range of applications for Concrete-Filled Steel Tube (CFT) member because of its superior performance. Ductility estimation test of concrete-filled seismic resistant steel tubular columns, subjected to axial and cyclic lateral load, was carried out in this study. Seismic resistant steel tubes are manufactured using SN400B plates by a two-seam welding at center of the column width for cold press-formed shape plates of two pieces. A total of eight specimens were manufactured and tested with the parameters of width-thickness ratio of steel tubular column, axial load ratio, and loading conditions to act axial and cyclic lateral load two dynamic actuators were used. From test results, flexural strength, deformation capacity, energy dissipation capacity, and ductility behavior of columns were analyzed.

• Journal of Korean Society of Steel Construction
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• v.30 no.2
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• pp.77-85
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• 2018

A through diaphragm is often used to ensure their stiffness for moment-resisting connections using rectangular steel-tube column and H-shaped beam. The through-diaphragm connections, however, have some difficulties for their applicabilities to the field due to the complexity of the fabrication and construction processes. This study thus proposes a new modular system of steel structures assembled only using bolts without welding, by bringing a connection module composed of rectangular steel-tube column, H-shaped beam and oneway bolt onto the site. An experimental study to evaluate the seismic performance of the proposed connection details based on the new modular system is then conducted. The length and type of the inner reinforcement plate are considered as the primary design parameters, and the strength, stiffness, ductility and energy dissipation capability of the new connections are experimentally analyzed by comparison to those of conventional through diaphragm connections.

• Geotechnical Engineering
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• v.3 no.1
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• pp.7-24
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• 1987

Preloading surcharge method along with vertical drains was adopted to improve the performance of a very soft marine clay deposit. The onshore deposit, located in the Ulsan Bay area, consists of a 2 to 10m thick, very soft, highly compressible marine clay layer developed just below. the sea water level. The initial undrained shear strength of the clay layer was about 0.6 ton/m2. But, the deposit was designed after treatment to support some auxiliary facilities for a new ilo refinery plant, requiring bearing capacities of 3.6 to 5.4 ton/m2 and maximum allowablee settlement of less than 7.5cm. A total of 35, 000 wick drains Ivas installed to expedite drainage during preloading, and surcharge loads of up to 5m above the original ground level were applied in a step-by-step loading sequence to prevent ground failure by excess surcharge loads. An extensive program of field instrumentation was implemented to monitor the behavior of the clay deposit. Measurers!ends included settlements, excess pore pressure and its dissipation, ground farmer level fluctuation, and lateral movement of the so(t clay layer under the preloads. This paper describes the design concepts, construction methods and control procedures used for improvement of the clay layer. It also presents the ground behavior measured during construction, rind comparisons with theoretical predictions.