• Journal of Korean Society of Forest Science
• /
• v.81 no.4
• /
• pp.383-392
• /
• 1992

The objective of this study is to evaluate the impacts on the domestic timber supply potential of forest resources management policies such as the extention of forest management infrastruture and setting aside more forest lands for the provision of environmental goods. To this end, the domestic timber supply functions were estimated using time series data for the period 1970-1990 and were used to predict the future trends in timber production in the Republic of Korea. For this purpose, a set of scenarios based on the forest road density and forest inventory growth were designed for the next 40 years. The timber supply behavior in Korea was found to be different by species group : domestic supply of softwood roundwood is inelastic with respect to its ovum price while that of hardwood elastic. The effect of forest road construction on the domestic timber production seems to be insignificant yet. The model simulation aided by policy scenarios revealed that the future timber supply potential will be largely restricted if the policy option with emphasis on the provision of environmental goods from the forest resources were adopted.

• Journal of the Korea Concrete Institute
• /
• v.17 no.1 s.85
• /
• pp.85-94
• /
• 2005

Post-tensioned Precast concrete System(PPS) consists of U-shaped precast wide beams and concrete column. The continuity of beam-column joint is provided with floor concrete cast on the PC shell beam and post-tensioning. The purpose of this paper is to evaluate the response of PPS interior beam-column joint subjected to cyclic lateral loading. To this end, an experimental investigation was performed with three half-scale specimens of interior connection. The design parameters are the amount of beam reinforcement placed inside the joint core. The test results showed that cracks were distributed well without my significant degradation of strength and ductility. Also, it was found that the prestressing may affect to alter the torsional crack angle. And the specimens sufficiently resist up to limiting drift ratio of 0.035 in accordance with the provisional by ACl of acceptance criteria for concrete special moment frames.

• Journal of the Korean Geotechnical Society
• /
• v.30 no.4
• /
• pp.35-45
• /
• 2014

Limit equilibrium methods of slope stability analysis have been widely adopted mainly due to their simplicity and applicability. However, the conventional methods may not give reliable and convincing results for various geological conditions such as nonhomogeneous and anisotropic soils. Also, they do not take into account soil slope history nor the initial state of stress, for example excavation or fill placement. In contrast to the limit equilibrium analysis, the analysis of deformation and stress distribution by finite element method can deal with the complex loading sequence and the growth of inelastic zone with time. This paper proposes a technique to determine the critical slip surface as well as to calculate the factor of safety for shallow failure on partially saturated soil slope. Based on the effective stress field in finite element analysis, all stresses are estimated at each Gaussian point of elements. The search strategy for a noncircular critical slip surface along weak points is appropriate for rainfall-induced shallow slope failure. The change of unit weight by seepage force has an effect on the horizontal and vertical displacements on the soil slope. The Drucker-Prager failure criterion was adopted for stress-strain relation to calculate coupling hydraulic and mechanical behavior of the partially saturated soil slope.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.26 no.6
• /
• pp.455-462
• /
• 2013

The effects of earthquakes can be devastating especially to existing structures that are not based on earthquake resistant design. This study proposes a steel grid shear wall that can provide a sufficient lateral resistance and can be used as a seismic retrofit method. The pushover analysis was performed on RC structure with and without the proposed steel grid shear wall. Obtain the performance point that the target structure for seismic loads applied to evaluate the response and performance levels. The capacity spectrum at performance point is nearly elastic range, so satisfied the performance objectives(LS level). And response modification factor(R factor) were calculated from the pushover analysis. The R factor approach is currently implemented to reflect inelastic ductile behavior of the structures and to reduce elastic spectral demands from earthquakes to the design level. The R factor increases from 2.17 to 3.25 was higher than the design criteria. As a result, according to reinforcement by steel grid shear wall, strength, stiffness, and ductility of the low-rise RC structure has been appropriately improved.

• Journal of Korea Port Economic Association
• /
• v.33 no.1
• /
• pp.47-59
• /
• 2017

The objective of this study is to determine the short run and long run dynamics between maritime import volume (IMV), industrial production (IP), and real effective exchange rate (REER) of the Korean Won over the REER of certain major currencies (US Dollar, Chinese Yuan, and Japanese Yen) in Korea's Jeonnam province. The Johansen and Juselius cointegration results reveal that at least one cointegration vector or long-run relationship exists. Hence, this study estimated the long run equilibrium equation, which indicates that both IP and REER are inelastic, although the former is bigger than the latter. Moreover, the dynamic causality analysis reveals short and long-run unidirectional causality from IP and REER to IMV in all three models. Further, in all the models, the results indicate short run unidirectional causality from REER to IP. In addition, the impulse response (IR) results show that the impulse of IP and REER decayed after four months. Additionally, the IR analysis results indicate that the REER of the Korean Won over the REER of Japanese Yen is the biggest with respect to the impact of relative REER on IP, which is the proxy variable of regional real income. Thus, empirical results indicated that real income and REER play an important role in determining the Jeonnam's maritime import demand behavior in the short run and long run. More importantly, substantial actions reducing unexpected fluctuation of the REER and real income based on micro and macro economic policies will increase the imported volume in the ports of the Jeonnam province.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.6 no.6
• /
• pp.33-39
• /
• 2002

Response Modification Factor(R-factor) approach is currently implemented to reflect inelastic ductile behavior of the structures and to reduce elastic spectral demands from earthquakes to the design level. However R factors were set empirically and simply based on the professional committee consensus on observed performance of building structures during past earthquakes. Consequently some major shortcomings linked to the current R factor approach have been pointed out. Using reinforced concrete intermediate moment-resisting frames(RC IMRFs), an analytical procedure is presented in this paper to establish R factor rationally. To this end, analytical R values were evaluated based on N2 Method and compared with the values recommended by IBC 2000. Overall, the analytical results correlated well with the code values. However the results also revealed that R factor might strongly depend on the system fundamental period. As evidenced by the interstory drift index(IDI) analysis results of this study, current R-factor based(or, Life Safety based) design tends to fail in fulfilling other implicit and hopeful performance objectives such as immediate Occupancy and Collapse Prevention. Performance based design(PBD) appears to be a promising approach to meet the multi level seismic performance objectives assigned to the building structures of nowadays.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.7 no.6
• /
• pp.101-108
• /
• 2003

Small-scale models have been frequently used for experimental evaluation of seismic performance because of limited testing facilities and economic reasons. However, there are not enough studies on similitude law for analogizing prototype structures accurately with small-scale models, although conventional similitude law based on geometry is not well consistent in the inelastic seismic behavior. When fabricating prototype and small-scale model of reinforced concrete structures by using the same material. added mass is demanded from a volumetric change and scale factor could be limited due to size of aggregate. Therefore, it is desirable that different material is used for small-scale models. Thus, a modified similitude law could be derived depending on geometric scale factor and equivalent modulus ratio. In this study, compressive strength tests are conducted to analyze equivalent modulus ratio of micro-concrete to normal-concrete. Equivalent modulus ratios are divided into multi phases, which are based on ultimate strain level. Therefore, an algorithm adaptable to the pseudodynamic test. considering equivalent multi-phase similitude law based on seismic damage levels, is developed. In addition, prior to the experiment. it is verified numerically if the algorithm is applicable to the pseudodynamic test.

• Computational Structural Engineering
• /
• v.8 no.3
• /
• pp.103-111
• /
• 1995

Evaluating nonlinear response of a MDOF system under dynamic stochastic loads such as seismic excitation usually requires excessive computational efforts. To alleviate this computational difficulty, an approximation is developed in which the MDOF inelastic system is replaced by a simple nonlinear equivalent system(ENS).Me ENS retains the most important properties of the original system such as dynamic characteristics of the first two modes and the global yielding behavior of the MDOF system. The system response is described by the maximum global(building) and local(interstory) drifts. The equivalency is achieved by two response scaling factors, a global response scaling factor R/sub G/, and a local response scaling factor R/sub L/, applied to the responses of the ENS to match those of the original MDOF system. These response scaling factors are obtained as functions of ductility and mass participation factors of the first two modes of structures by extensive regression analyses based on results of responses of the MDOF system and the ENS to actual ground accelerations recorded in past earthquakes. To develop the ENS with two response scaling factors, Special Moment Resisting Steel Frames are considered. Then, these response scaling factors are applied to the response of ENS to obtain the nonlinear response of MDOF system.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.3A
• /
• pp.149-160
• /
• 2012

Corrugated steel plates have several advantages such as high resistance for shear without stiffeners, minimization of welding process, and high fatigue resistance. To take advantage of these benefits, several researchers have attempted to use corrugated steel plate as a web of I-girders. The lateral-torsional buckling is the major design aspect of such I-girders. However, lateral-torsional buckling of the I-girder with corrugated steel webs still needs to be investigated especially for a real loading condition such as non-uniform bending. This paper investigated the lateral-torsional buckling strength of the I-girder with corrugated steel webs under linear moment gradient by using finite element analysis. From the results, it was found that the buckling behavior of the I-girder with corrugated steel webs differed depending on the number of periods of the corrugation. Also, a simple equation for the moment gradient correction factor of the I-girder with corrugated steel webs was suggested. The inelastic lateral-torsional buckling strength of the I-girder with corrugated steel webs was then discussed based on current design equations for ordinary I-girders and the results of finite element analysis.

• Journal of the Korea Concrete Institute
• /
• v.14 no.3
• /
• pp.291-298
• /
• 2002

Recently, construction of reinforced concrete tall buildings is widely increased according to the improvement of material quality and design technology. Therefore, differential shortenings of columns due to elastic, creep, and shrinkage have been an important issue. But it has been neglected to predict the Inelastic behavior of RC structures even though those deformations make a serious problem on the partition wall, external cladding, duct, etc. In this paper, analysis system for prediction and compensation of the differential column shortenings considering time-dependent deformations and construction sequence is developed using the objected-oriented technique. Developed analysis system considers the construction sequence, especially time-dependent deformation in early days, and is composed of input module, database module, database store module, analysis module, and analysis result generation module. Graphic user interface(GUI) is supported for user's convenience. After performing the analysis, the output results like deflections and member forces according to the time can be observed in the generation module using the graphic diagram, table, and chart supported by the integrated environment.