• Computational Structural Engineering
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• v.9 no.4
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• pp.229-237
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• 1996

In some current procedures, ground motions from different sources have been scaled by their peak ground accelerations and combined to obtain smoothed response spectra for specific regions. As consideration of the inelastic deformation capacity of structure, inelastic deformations are permitted under seismic ground excitation in all codes. In the ATC(Applied Technology Council) and UBC(Uniform Building Code), the inelastic design spectrum is obtained by reducing the elastic design spectrum by a factor that is independent of structural period. In this study, the average of nonlinear response spectra calculated from a sample of 20 records for each event are constructed to obtain the smoothed response spectra. These response spectra are used to examine the effects of structural strength factors such as the yield strength ratio and damping value. Through the regression analysis of nonlinear response of system for a given damping value and yield strength ratio, the required yield strength for seismic design can be estimated for a certain earthquake event. And a response modification coefficient depending on the natural period for current seismic design specifications are proposed.

• Korean Journal of Poultry Science
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• v.17 no.3
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• pp.217-223
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• 1990

This study was undertaken to find out the changes of chemically modified egg albumen grl after heat treatment at $95^{\circ}C$ for 30 minutes or at $120^{\circ}C$ for 30 minutes. Acetylation and succinylation increased the hardness of egg albumen gel, it was rather higher at high heat treatment($120^{\circ}C$, 30min.) than at low heat treatment($95^{\circ}C$, 30min). The cohesiveness of egg albumen gel was improved remarkably by succinylation and maleylation at both low and high heat treatment. The lightness and yellowness of egg albumen gel were decreased by chemical modification. Initial heat denaturation temperature of egg albumen was increased by 11$^{\circ}C$ by acetylation, by $12.5^{\circ}C$ by maleylation and by ,$14.5^{\circ}C$ by succinylation.

• Journal of the Korean Ceramic Society
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• v.43 no.1 s.284
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• pp.38-41
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• 2006

Surface of PC (Polycarbonate) and PES (Polyethersulphone) treated by plasma modification with rf power from 50 W to 200 W substrates in Ar (3 sccm), $O_2$ (12 sccm) atmosphere. From the results of modified substrates in XPS (X-ray Photoelectron Spectroscopy), the ratio of oxide containing bond increased with rf power. As the rf power was 200 W, the contact angle was the lowest value of 14.09 degree. And the datum from AFM (Atomic Force Microscopy), rms roughness value of PES and PC substrates increased with rf power. We could deposit $Ta_2O_5$ with good adhesion on plasma treated PES and PC substrates using by in-situ rf magnetron sputter.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.3
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• pp.115-122
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• 2001

Bridge load rating calculations provide a basis for determining the load carrying capacity of bridges. Load rating requires engineering judgement in determining a rating value that is applicable to maintaining the safe use of the bridge and arriving at posting and permit decisions. Load testing is an effective means in calculating the rating value of bridge. In Korea, load carrying capacity of bridge is modified by response modification factor that is determined from comparisons of measured values and analysis results. This paper presents the development of a method for determining the response the modification factor, using traffic loads. The proposed method is based on the results of computer simulations of traffic action effects. The simulation program generates random traffic actions for defined traffic conditions and determines the frequency distribution of maximum traffic action effects. A comparison between the proposed method and the present method shows good agreement in estimating the modified load carrying capacity of bridges.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7182-7188
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• 2015

Recently, to improve manual mapping method, digital mapping using high-resolution camera and laser scanner has increasingly attracted attention and the relevant study is reportedly on the rise. In this study, laboratory and field test which are intended to quantitatively analyze and estimate the weathering degree which is one of the engineering characteristics of tunnel face using laser scanner that integrates high-solution imaging technique have been conducted. In a bid to analyze correlation between reflectance of laser scanner and weathering degree, investigation of the factors influencing on reflectance was carried out. And to minimize the effect on RGB value which is one the critical influential factors on reflectance, modification equation obtained from lab test was proposed. Modification equation proposed in this study was verified by comparing the values before and after correction using the data obtained by scanning. Consequently, weathering index estimated by modified reflectance appeared very similar with dominant weathering degree and weathering ratio monitored at the field.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.203-207
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• 2003

Ion implantation has been shown to significantly alter the surface properties of polymers. Polycarbonate(PC) and Polyimide(PI) were irradiated with 50keV $N^+$, $Xe^+$ ions to the fluences of $1{\times}10^{16}{\sim}3{\times}10^{17}\;cm^2$. The ion beam-induced modification of the electrical conductivity and the related structural features have been studied for polymers. The beam-induced chemical and structural modifications have been investigated by using X-ray Phooelectron Spectroscopy(XPS) and Fourier Transform-Infrared Spectroscopy(FT-IR), while the modification of the electrical properties was followed by performing a complete set of sheet resistance measurements. Samples irradiated at higher fluence showed a good conductivity, with a saturation value of $10^7{\Omega}/sq$. The XPS data demonstrate that the modification of the electrical properties is due to the progressive formation with increasing ion fluence of a dense amorphous carbon network, while PF-IR data reveal that material degradations through bond breaking are the main effects.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.6
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• pp.856-861
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• 2016

This study compared the density of fish determined using three different echogram methods: the frequency-difference, time variable, and threshold modification methods. An acoustic survey was conducted off the coast of Jeju Island after sunset. Data at 38 and 120 kHz frequencies were collected using a commercial fishing vessel. As a reference point, the value of ${\Delta}MVBS_{120-38kHz}$ that distinguished fish from zooplankton using the 38 and 120 kHz frequencies was set at < 2 dB. The estimated density of fish along the survey line was 0.1-30.4, 0.1-64.3, and $0.1-51.7m^2/nmi^2$ using the frequency difference, time variable threshold, and threshold modification methods, respectively. The results of this study constitute basic research for estimating fish densities.

• International Journal of Advanced Culture Technology
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• v.3 no.2
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• pp.132-137
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• 2015

The purpose of this paper was to investigate the effects of solution treatment time and Sr-modification on the microstructure and property of the Al-Si piston alloy. It was found that as-cast microstructures of unmodified and Sr-modified Al-Si alloys consisted of a coarse acicular plate of eutectic Si, $Cu_3NiAl_6$ and $Mg_2Si$ phases in the ${\alpha}$-Al matrix but different in size and morphology. Both size and inter-particle spacing of Si particles were significantly changed by increasing of the solution treatment time. After a short solution treatment, the coarse acicular plate of the eutectic Si appears to be fragmented. Fully modified microstructure of Sr-modified alloy can reduce the solution treatment time to shorter compared to unmodified alloy. The maximum of a peak hardness value is found in the very short solution treatment of both Al-Si piston alloys. Compared to 10 h solution treatment, the solution treatment of 2-4 h is sufficient to achieve appropriate microstructures and hardness. The short solution treatment is very useful to increase the productivity and to reduce the manufacturing cost of the Al-Si piston alloys.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.179-182
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• 2009

Concrete containing styrene-butadiene latex is widely used, nowadays, as a protective system for bridge. Latex modification mortar have taken advantage of latex modification concrete advantage that is used in existing, Also, when repair, protection and sticking performance of concrete overlay waterproof agent were known as that are good. Replace and experimented from fine aggregate to recycled aggregate to secure economic performance than existing latex modification concrete. Recycled fine aggregate has low quality because it contains large amount of old mortar. So, its usage is limited to a lower value-add, such as the roadbed material etc. This study is purposed to improve the performance of mortar made of recycled fine aggregate. For this, recycled aggregate mortar was produced with latex, and fluidity, strength were examined. Test result indicate that mortar using recycled fine aggregate is higher compressive and flexural strength than mortar using river sand.

• Journal of KSNVE
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• v.4 no.4
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• pp.479-486
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• 1994

The Finite Element Method(FEM) generally used for the structural analysis has some defects, i.e. a great deal of computational time and huge memory capacity of computer are needed in the application to large and/or complex structures, etc. Therefore the Component Mode Synthesis method(CMS), one of sub-structure synthesis methods, was made to improve such demerits and has been developed up to now. In optimum structural modification problems, the sensitivity analysis method is useful, where the sensitivity-calculated by Fox's suggestion-is defined as the diffentials of design variables for the objective values. This paper discusses the vibration minimization techniques for the oper box type structure, in which it is assumed that an engine operates at 10-40Hz range. The results obtained are as follow; (1) The sensitivity of natural frequency could be easily obtained by sensitivity analysis method and the optimum position to insert pillars could be found by using it. (2) The rates of structural modification could be exactly obtained and the natural frequency observed could be easily shifted to the objective value. (3) The maximum amplitude around natural frequency noted could be nearly reduced to 1/25 by modification.