• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.1
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• pp.56-65
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• 2022

The electrochemical corrosion properties of austenitic AISI 304 steel subjected to a long-term-aging heat treatment were investigated. AISI 304 steel was aged at 700 ℃ for up to 10,000 h. The variation in the microstructure of the aged specimens was observed by optical microscopy and scanning electron microscopy. Electrochemical polarization experiments were performed to obtain the corrosion current density (Icorr) and corrosion potential (Ecorr). Analyses indicated that the metastable intermetallic carbide M₂₃C₆ formed near the γ/γ grain boundary and coarsened with increasing aging time; meanwhile, the δ-ferrite decomposed into the σ phase and into M₂₃C₆ carbide. As the aging time increased, the current density increased, but the corrosion potential of the austenitic specimen remained high (at least 0.04 ㎛/cm²). Because intergranular carbide was absent, the austenitic annealed specimen exhibited the highest pitting resistance. Consequently, the corrosion resistance of austenitic AISI 304 steel decreased as the aging heat treatment time increased.

• Journal of Environmental Science International
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• v.33 no.3
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• pp.227-234
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• 2024

We investigated the change in land-use alteration in a 45 km × 45 km area around the Upo wetlands in 1920s(before the Japanese occupation period), 1950s(immediately Korean independence) and the period 1970s to 2000s. These data can guide in understanding surface environmental changes in the lower Nakdong River from the early 20^th century to the present. The influence of the long-term decreasing trend of the wetland area at the Upo Swamp was evaluated using a high-resolution local circulation model. The cooling effect of the wetlands on surface air during the daytime in summer(e.g, early August) was approximately 2℃ greater in the 1920s than in the 2000s, which is attributed to wider water areas in the 1920s. Additionally, long-term changes in land use have caused changes in the convergence zone of local circulation wind.

• Information and Communications Magazine
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• v.3 no.1
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• pp.52-63
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• 1986

This paper discusses the network evolution strategies, worldwide trends in fiber optics systems, fiber hub in KTA access network, positioning the access network for new digital services - DLC(Digital Loop Carrier), CSA(Carrier Serving Area), and fiber optics systems overlay in the existing access network and its evolution toward near term ISDN.

• KCID journal
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• v.6 no.1
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• pp.39-47
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• 1999

One of the important features of a beach face is the dynamic response to the ever-changing waves and tides imposed from the body of water. Furthermore, human activities at or near the beach can enforce the characteristic changes on tidal motions and wave

• Journal of the Chungcheong Mathematical Society
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• v.20 no.4
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• pp.503-514
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• 2007

In this paper, we investigate the generalized Hyers-Ulam stability of the functional inequality $$||af(x)+bf(y)+cf(z)||{\leq}||f(ax+by+cz))||+{\phi}(x,y,z)$$ associated with Cauchy additive mappings. As a result, we obtain that if a mapping satisfies the functional inequality with perturbing term which satisfies certain conditions then there exists a Cauchy additive mapping near the mapping.

• Structural Engineering and Mechanics
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• v.24 no.5
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• pp.601-620
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• 2006

The paper presents an effective stiffness model for deformational analysis of reinforced concrete cracked members in bending throughout the short-term loading up to the near failure. The method generally involves the analytical derivation of an effective moment of inertia based on the smeared crack technique. The method, in a simplified way, enables us to take into account the non linear properties of concrete, the effects of cracking and tension stiffening. A statistical analysis has shown that proposed technique is of adequate accuracy of calculated and experimental deflections data provided for beams with small, average and normal reinforcement ratios.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.240-244
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• 2010

The surface segregation and surface order near the order-disorder phase transition of FeCo alloy was studied through Monte Carlo simulation of an Ising type model Hamiltonian. The results showed that the proper choice of Hamiltonian parameters could reproduce the recent observation of surface order above the transition temperature and that the field term played dominant role.

• 한국전산유체공학회:학술대회논문집
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• 1995.10a
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• pp.126-131
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• 1995

In this paper we study steady capillary-gravity waves in a two-layer fluid bounded above by a free surface and below by a horizontal rigid boundary with a small obstruction, Two critical speeds for the waves are obtained. Near the smaller critical speed, the derivation of the usual forced KdV equation (FKdV) fails when the coefficient of the nonlinear term in the FKdV vanishes. To overcome this difficulty, a new equation called a forced extended KdV equation (FEKdV) governing interfacial wave forms is obtained by a refined asymptotic method. Various solutions and numerical results of this equation are presented.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.12
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• pp.10-17
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• 1993

In this paper, CCF(Call Control Function), functional entity for basic call processing in SSP(Service Switching Point), is designed and implemented. This functional entity can provide the IN(Intelligent Network) services which are included in CCITT CS-1(Capability Set-1), near-term process for IN Architecture. UIO(Unique Input Output) method, one of the thest sequence generation methods for the finite state machine, is used for the implementation test of this functional entity.

• Journal of the Korea Society for Simulation
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• v.12 no.1
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• pp.35-48
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• 2003

This paper suggests the long-term strategy of the production distribution planning considering the capacity of factory production and the uncertain demand in a supply chain. This paper determines the near optimal capacity of factory production by using the advantages of mathematical and simulation models. Also, the relationship between the capacity from the suggested model and the strategy of production and distribution in a supply chain is studied. Arena is used for modeling and analysis.