• International Journal of Highway Engineering
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• v.15 no.1
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• pp.37-45
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• 2013

PURPOSES: This study is to analyze different vehicle load effects for a bridge design of South and North Korea in order to prepare a common design specification and to secure the safety of transportation when the highway bridges of South and North Korea use together. METHODS: Based on the literature review, this study considers vehicle load effects by comparing different characteristics of the standard vehicle and other differences of the bridge design specification between South and North Korea. And structural modeling of three-span continuous PSC Beam Bridge are analyzed and the bridge capacity according different vehicle loads of South and North Korea is evaluated. RESULTS: The result of this study indicates that the bridge capacity and the design vehicle weight of North Korea are smaller than the bridge capacity and the design vehicle weight of South Korea. Also this study demonstrates that the design vehicle array and other characteristics of North Korea are very different than the design vehicle array and other characteristics of South Korea. CONCLUSIONS: It is expected that the outcomes of this study can be useful in the set-up of South-North Bridge Specification because similar previous studies are rarely found.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.2
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• pp.139-149
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• 2000

In the preliminary design stage of prestressed concrete (PSC) box girder bridges, the design factors decided by inexperience designer could heavily affect to the results of final design. There is a possibility that the design ends up with an excessively wasteful design. To achieve an economical design with preventing an excessive design, the optimal design technique has been developed using ADS optimal program and SPCFRAME in this study. The objective function for the optimal design problem is the material cost of box girders and constrained functions are constituted with design specifications and workability. The Sequential Unconstraint Minimization Technique (SUMT) is used for the optimal design in this study. We designed an uniform cross-section bridge and an ununiform cross-section bridge in the same design condition by optimal design technique developed in this study. Analyzing the results obtained for various tendon layouts, we suggest a standard tendon layout which gives the most effective structural behavior.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.686-691
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• 2000

최근 들어 인터넷의 사용이 급격히 증가함에 따라 인터넷의 백본망에는 패킷 전달의 고속성, 확장성 뿐만 아니라 QOS 보장을 요구하게 되었다. 효과적인 인터넷 백본망을 구현하기 위해 본 논문에서는 Multi-Protocol Label Switching(MPLS)를 고려하고 MPLS 에서 인터넷 Quality Of Service(QOS) 서비스 모델 중 백본망에 적합한 Differentiated Service(DS) 모델을 그대로 제공하기 위해 MPLS 와 DS 의 연동에 대한 문제를 다룬다. 우선 MPLS 에서 QOS 제공을 위한 기능요소를 정성적으로 분석한다. 그리고 두 DS 망 가운데 ATM 기반의 MPLS 망을 두고 있는 경우를 가정하여, 종단대 종단간 DS 제공을 위하여 DS 망과 MPLS 망에서의 시그널링 과정을 제안한다. 즉, DS 의 BB 로부터 SLA 를 위한 신호를 MPLS 의 입구 라우터에서 해석하여 DS Type-Length-Value(TLV)를 만들고 이를 이용하여 Constraint-based Label Distribution Protocol(CR-LDP) 시그널링을 통해 마다 Label-Only-Inferred-PSC LSP(L-LSP)를 설립하여 MPLS 에서 DS QOS 를 그대로 제공한다. 또한 입구 DS BB 로부터의 정보를 MPLS 망을 통해 BB 에게 보낸다.

• Electronic Materials Letters
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• v.14 no.6
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• pp.712-717
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• 2018

In this letter, we have introduced copper chloride ($CuCl_2$) as an additive in the $CH_3NH_3PbI_3$ precursor solution to improve the surface morphology and crystallinity of $CH_3NH_3PbI_3$ films in a single solvent system. Our optimized perovskite solar cells (PSCs) with 2.5 mol% $CuCl_2$ additive showed best power conversion efficiency (PCE) of 15.22%. The PCE of the PSCs fabricated by $CuCl_2$ (2.5 mol%) additive engineering was 56% higher than the PSC fabricated with pristine $CH_3NH_3PbI_3$.

• Bulletin of the Korean Chemical Society
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• v.21 no.8
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• pp.769-773
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• 2000

The dependence of photoluminescence (PL) and photoluminescence itation (PLE) on preparation condi-tions and the aging of porous silicon carbide (PSC) have been investigatted. The fiber size of the material pre-pared under dark-current mode, labele d DCM, was larger than that of the photoassisted (PA)process.The intensity of the PL spectrum for the PA condition was higher than that of the DCM condition. The PA condition giving small fiber size exhibited amore prominent high-energy component but the emission bands of both con-ditionsobserved were rather similar. The origin of the PL may have played an importantrole in the surface defect center introduced by the reaction conditions ofHFatthe surface of the silicon carbide. Selective excita-tion of the PL bandsusingdifferent excitation wavelengths has been used to identify distinct componentswith-in the PL bandwidth. Two main PL bands with peak wavelength of494 and534 nm were clearly resolved. On the other hand, selectivc emission of the PLEbands using different emission wavelengths has been used to identify distinct components within the PLE bandwidth. The higher energy band with peak wavelength of 338 nm and the lower energy bands involving 390,451 and 500 nm were clearly resolved. According to the pro-ionged aging in air, PL spectra appearedasone band, This emission probably originated from states localized to the band-to-band recombination due to the oxidation on the crystallite surface.

• Journal of the Korean Society of Safety
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• v.34 no.5
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• pp.103-110
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• 2019

In order to reduce the accidents occurring at construction sites, it is necessary to approach with harmonious measures considering various aspects such as systems, training, facilities, and protection equipments. Suggestion of safe construction method can be a good alternative. In the previous study, the half-depth precast deck with RC rib panel was proposed as an alternative method for safe bridge deck construction, and the performance required by the design code was verified through a four-point bending test. But the actual bridge deck is subjected to the repetitive action of the wheel load rather than the bending condition due to the four-point load. In this study, fatigue test was performed by repeating the wheel load $2{\times}10^6$ cycles to verify the safety of the half-depth precast deck with RC rib panel under actual conditions. As a result, fatigue effect due to repetition of wheel load was not significant in terms of serviceability such as crack width and deflection. In the residual strength test conducted after the fatigue test, the half-depth precast deck with RC rib panel failed by punching shear which is typical failure mode of bridge decks and the residual strength was similar to the punching strength of the RC and PSC bridge decks in spite of the fatigue effects.

• Structural Engineering and Mechanics
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• v.50 no.5
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• pp.617-633
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• 2014

Because the elevated temperature degrades the mechanical properties of materials used in containments, the global behavior of containments subjected to the internal pressure under high temperature is remarkably different from that subjected to the internal pressure only. This paper concentrates on the nonlinear finite element analyses of the nuclear power plant containment structures, and the importance for the consideration of the elevated temperature effect has been emphasized because severe accident usually accompanies internal high pressure together with a high temperature increase. In addition to the consideration of nonlinear effects in the containment structure such as the tension stiffening and bond-slip effects, the change in material properties under elevated temperature is also taken into account. This paper, accordingly, focuses on the three-dimensional nonlinear analyses with thermal effects. Upon the comparison of experiment data with numerical results for the SNL 1/4 PCCV tested by internal pressure only, three-dimensional analyses for the same structure have been performed by considering internal pressure and temperature loadings designed for two kinds of severe accidents of Saturated Station Condition (SSC) and Station Black-out Scenario (SBO). Through the difference in the structural behavior of containment structures according to the addition of temperature loading, the importance of elevated temperature effect on the ultimate resisting capacity of PCCV has been emphasized.

• International Journal of Railway
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• v.8 no.1
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• pp.5-9
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• 2015

Reliability based limit state design method is replacing traditional deterministic designs such as allowable stress design and/or ultimate strength design methods in world trends. European design code(Eurocode) has adopted limit state design, and Korea road bridge design standard has also recently been transferred to limit state design method. In this trend, Korea railroad design standard is also preparing for adopting the same design concept. While safety factors are determined empirically in traditional design, load combinations as well as load factors are determined by solving limit state equations. General partial safety factors are evaluated by using AFORM(Advanced First Order Reliability Method) in the reliability based limit state design method. In this study sensitivity analysis is carried out for a dead load factor and a live load factor. Relative precisions of the dead load and the live load factors are discussed prior to the AFORM analysis. Furthermore the sectional forces of design and the material quantities required by two different design methods are compared for a PSC box girder railway bridge.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.854-863
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• 2008

A high attention has been paid on the running safety of Korean high-speed train, KTX. In running of KTX on bridge, the running unsafety problem issued from a resonance phenomenon of bridge, which was usually caused by the periodic wheel-loads of train. Therefore, many researches on this running safety of train on bridge have been conducted by domestic or foreign researchers. In this paper, for PSC box-girder bridge which is the representative high-speed railway bridge type, some numerical analyses on the dynamic characteristics of bridge with the non-periodic wheel-loads through vehicle size adjustment were performed. These numerical analyses shows the fact that the resonance phenomenon on bridge was mitigated through vehicle size adjustment. Additional numerical analyses on the vibration reduction of bridge in accordance with the location of size-adjusted vehicle were performed. From these results, it was represented that the adjustment of vehicle size has an effect on the running safety of train as well as the ride comfort.

• Structural Engineering and Mechanics
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• v.69 no.3
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• pp.347-359
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• 2019

This paper aims to evaluate the behavior of Dorim-Goh bridge in Seoul, Korea, under static and dynamic loads effects by ambient trucks. The prestressed concrete (PSC) girders and reinforcement concrete (RC) slab of the bridge are evaluated and assessed. A short period monitoring system is designed which comprises displacement, strain and accelerometer sensors to measure the bridge performance under static and dynamic trucks loads. The statistical analysis is used to assess the static behavior of the bridge and the wavelet analysis and probabilistic using Weibull distribution are used to evaluate the frequency and reliability of the dynamic behavior of the bridge. The results show that the bridge is safe under static and dynamic loading cases. In the static evaluation, the measured neutral axis position of the girders is deviated within 5% from its theoretical position. The dynamic amplification factor of the bridge girder and slab are lower than the design value of that factor. The Weibull shape parameters are decreased, it which means that the bridge performance decreases under dynamic loads effect. The bridge girder and slab's frequencies are higher than the design values and constant under different truck speeds.