• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_2
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• pp.501-507
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• 2021

In this study, In order to prevent the safety accidents caused by the sliding, to develop the non-slip grating, the stability judgment based on the span length of the grating and the gap of the bearing bar is performed. The structural analysis of Grating was carried out in accordance with the provisions set out in Grating's load-bearing test conditions. As the span length increases, the deflection increases and the stress and span length tend to be proportional to each other. It was shown that the larger the span, the linear increase in stress and exponential increase in deformation of grating. The maximum stress of grating was approximately 58.2 MPa, indicating a very stable safety rate of about 4.3 compared to the yield strength of the grating material. Based on these results, it will be able to be utilized as the basic data for determining the optimal dimensions of non-slip grading by performing optimal designs in the future.

• Journal of information and communication convergence engineering
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• v.19 no.4
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• pp.199-204
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• 2021

We propose a dispersion-managed link with a non-midway optical phase conjugator (OPC), in which the residual dispersion per span (RDPS) of each fiber span is different for each transmission section before and after OPC. We numerically demonstrate the compensation for 960-Gb/s wavelength-division multiplexed (WDM) signals distorted by chromatic dispersion and Kerr nonlinearity of the fiber. We consider different cases for non-midway OPC, including six fiber spans - OPC - 14 fiber spans and 14 fiber spans - OPC - 6 fiber spans. The numerical results show that the compensation of the distorted 960 Gb/s WDM is more efficient when the OPC is placed after 6-th fiber span as compared to after the 14-th fiber span. Our simulation results also indicate that the compensation effect increases when the difference in net residual dispersion between both transmission sections is not large, but they are not the same. Under this condition, the larger the magnitude of the RDPSs of each fiber span, the greater the compensation.

• Annual Conference on Human and Language Technology
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• 2021.10a
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• pp.31-35
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• 2021

기계독해 시스템은 주어진 질문에 대한 답변을 문서에서 찾아 사용자에게 제공해주는 질의응답 작업 중 하나이다. 기존의 기계독해는 대부분 문서에 존재하는 짧고 간결한 답변 추출 문제를 풀고자 했으며 최근엔 불연속적인 범위를 추출하는 등의 확장된 문제를 다루는 데이터가 공개되었다. 불연속적인 답변 추출은 실제 애플리케이션에서 사용자에게 정보를 유연하게 제공해줄 수 있다. 따라서 본 논문에서는 기존의 간결한 단일 범위 추출에서 확장된 다중 범위 추출 시스템을 제안하고자 한다. 제안 모델은 문서를 구성하는 모든 토큰의 조합으로 구성된 Span Matrix를 통하여 다중 범위 추출 문제를 해결하고자 하며 실험을 통해 기존 연구들과 비교하여 가장 높은 86.8%의 성능을 보였다.

• Journal of Korean Association for Spatial Structures
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• v.24 no.2
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• pp.101-109
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• 2024

In this study, the characteristics of wind pressure distribution on circular retractable dome roofs with a low rise-to-span ratio were analyzed under various approaching flow conditions by obtaining and analyzing wind pressures under three different turbulent boundary layers. Compared to the results of previous studies with a rise-to-span ratio of 0.1, it was confirmed that a lower rise-to-span ratio increases the reattachment length of the separated approaching flow, thereby increasing the influence of negative pressure. Additionally, it was found that wind pressures varied significantly according to the characteristics of the turbulence intensity. Based on these experimental results, a model for peak net pressure coefficients for cladding design was proposed, considering variations in turbulence intensity and height.

• Structural Engineering and Mechanics
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• v.73 no.6
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• pp.641-649
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• 2020

The determination of midtower longitudinal stiffness has become an essential component in the preliminary design of multi-tower suspension bridges. For a specific multi-tower suspension bridge, the midtower longitudinal stiffness must be controlled within a certain range to meet the requirements of sliding resistance coefficient and deflection-to-span ratio. This study presents a numerical method to divide different types of midtower and determine rational range of longitudinal stiffness for rigid midtower. In this method, influence curves of midtower longitudinal stiffness on sliding resistance coefficient and maximum vertical deflection-to-span ratio are first obtained from the finite element analysis. Then, different types of midtower are divided based on the regression analysis of influence curves. Finally, rational range for longitudinal stiffness of rigid midtower is derived. The Oujiang River North Estuary Bridge which is a three-tower four-span suspension bridge with two main spans of 800m under construction in China is selected as the subject of this study. This will be the first three-tower four-span suspension bridge with steel truss girders and concrete midtower in the world. The proposed method provides an effective and feasible tool for engineers to design midtower of multi-tower suspension bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.125-130
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• 2001

A existing design method of PSC girder bridges, according to total service loads, stress required tendon force at a time. Because this design method increases beam depth, design of long span is difficult. However, As UC girder stressing at difficult loading stages reduces sectional depth of PSC girder, both design and operation of long span bridges is possible. so, this study analyzes the effect of design parameter (Girder Strength, Girder Spacing, Span Length, Joint Strength) on the beam depth of IPC girder continuous bridges, and shows sectional depth of UC girder for design of long span bridges. According to analysis, when a continuous bridges of same length span is at strength of joint over strength of girder of 600kg/$cm^{2}$, a change of beam depth is observed and when a continuous bridges of different span length is at strength of joint below strength of girder of 600kg/$cm^{2}$, a change of beam depth is observed. In two case, a change of beam depth is mostly observed over strength of girder of 350kg/$cm^{2}$ according to analysis of deflection data, a continuous bridges of IPC girder is nearly satisfied.

• Journal of Ecology and Environment
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• v.31 no.3
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• pp.207-211
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• 2008

We investigated the leaf demography of a temperate woody liana, Akebia trifoliata, in a temperate forest in Japan, Akebia is semi-evergreen: some leaves are shed before winter, while others remain through the winter. Previous studies of semi-evergreen species found that variation in leaf life span was caused by variation in the timing of leaf emergence, Leaves that appeared just before winter over-wintered, while leaves appearing earlier were shed, However, it is unclear whether leaves of the same cohort (i.e., leaves that appear at the same time within a single site) show variation in life span under the effect of strong seasonality. To separate variation in life span among the leaves in each cohort from variation among cohorts, we propose a new method - the single leaf diagram, which shows the emergence and death of each leaf. Using single leaf diagrams, our study revealed that Akebia leaves within a cohort showed substantial variation in life span, with some over-wintering and some not. In addition, leaves on small ramets in the understory showed great variation in life span, while leaves on large ramets, which typically reach higher positions in the forest canopy, have shorter lives, As a result, small ramets were semi-evergreen, whereas large ramets were deciduous, The longer lives of leaves on small ramets can be interpreted as a shade-adaptive strategy in understory plants.

• KSBB Journal
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• v.17 no.3
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• pp.295-301
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• 2002

The effects of nonionic surfactant (SPAN 20) on the desulfurization process by Rhodococcus sp. strain IGTS8 have been investigated at various oil/water ratios, pHs and concentrations of surfactant. The hexadecane containing DBT was employed as model oil. The presence of surfactant in the oil/water mixture stabilized the oil/water interface, thus enhanced the efficiency of desulfurization. The volume percentages of oil in the oil/water mixture were 30, 50 and 70%. The concentrations of surfactant were varied from 0 to 0.33 wt% relative to water phase. In general, the biodesulfurization efficiencies were decreased as the concentration of SPAN 20 and the volume percentage of oil phase increased.

• Journal of the Korean Society of Safety
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• v.23 no.2
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• pp.7-13
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• 2008

In a long-span bridge which is constructed on soft soil, it is requested to make a plan considering soil-structure interaction, and soil-structure interaction is partially under consideration at the actual bridge plan. Many researches on dynamic behavior of a bridge affected by soil-structure interacting have been accomplished, but it is difficult to estimate dynamic behavior of a bridge on soft soil accurately because of many uncertainties. This paper presents the results about dynamic response of a long-span suspension bridge in the site composed of soft soil considering incident angle of input ground motion. The effect of soft soil was evaluated by the use o computer program SASSI and a long-span suspension bridge was modeled by finite element program MIDAS. The effect of incident angle of input ground motion was investigated on the dynamic response of a long-span bridge.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.4
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• pp.595-604
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• 2016

This paper proposed the design bending moments of cantilever slabs with KL-510 load according to span length of long span decks. Their span length range is from 6.0 to 12.0 meter, and length of cantilever slabs is from 30 to 50 percent of their span length. The effects of orthotropic concrete decks, stiffness of steel girders and multiple lane loading factors (MLLF) were reflected in the design bending moments. The proposed design bending moments of cantilever slabs were compared to the design bending moments with DB-24 load.