• 한국군사과학기술학회지
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• 제12권2호
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• pp.236-247
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• 2009

In Korea, the driving system restriction criteria is strictly applied(gross weight 400kN, axial load 100kN). Especially after the Seoungsu Bridge accident, safety factor has been strictly applied. The Safety factor is applied to the cumulative results for each steps like design, construction, maintenance of the Bridge. Because of it, the bridge is undervalued compared to its capacity. So, this generates loss for both private and military sector(eg. logistical delays, structural damage, etc.). But analyzing data from many existing researches we have confirmed that the military heavy vehicle may pass through the first class bridges. In consequence, this study have focused on determining whether HETS vehicles can pass over the first class bridge, without safety issues, using MIDAS structural analysis program. The results have confirmed that the military heavy vehicle may pass over the bridge.

• Korean Journal of Mathematics
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• 제16권3호
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• pp.389-402
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• 2008

We show the existence of at least two solutions for a class of systems of the critical growth nonlinear suspension bridge equations with Dirichlet boundary condition and periodic condition. We first show that the system has a positive solution under suitable conditions, and next show that the system has another solution under the same conditions by the linking arguments.

• 한국구조물진단유지관리공학회 논문집
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• 제25권6호
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• pp.161-168
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• 2021

본 논문은 3종 및 법정 외 교량인 중소규모 교량에 대한 유지관리 체계를 수립하여 제안하는데 그 목적을 두고 있다. 국내 교량은 1, 2종 교량과 3종 및 법정 외 교량으로 구분된다. 3종 및 법정외 교량의 개소수는 많으나 1, 2종 교량에 비해 상대적으로 중요도가 낮은 것으로 판단된다. 따라서 본 논문에서는 이러한 중소규모 교량에 대한 유지관리 시나리오 체계를 수립하고자 한다. 하지만 중소규모 교량의 경우 그 개소수가 많아 1, 2종 교량과 같이 모든 교량에 대해 성능평가를 실시하는데 인력과 예산의 문제가 있다. 이에 따라 본 연구는 리스크 매트릭스 기법을 기반으로 교량의 기본적인 현황정보를 이용하여 현재 성능평가가 우선적으로 수행되어야할 교량을 선정하기 위한 기법을 개발하였으며, 개발된 기법에 대하여 실제 공용중인 교량을 대상으로 적용하였다.

• Korean Journal of Mathematics
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• 제16권3호
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• pp.355-362
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• 2008

We prove the existence of a unique positive solution for a class of systems of the following nonlinear suspension bridge equation with Dirichlet boundary conditions and periodic conditions $$\{{u_{tt}+u_{xxxx}+\frac{1}{4}u_{ttxx}+av^+={\phi}_{00}+{\epsilon}_1h_1(x,t)\;\;in\;(-\frac{\pi}{2},\frac{\pi}{2}){\times}R,\\{v_{tt}+v_{xxxx}+\frac{1}{4}u_{ttxx}+bu^+={\phi}_{00}+{\epsilon}_2h_2(x,t)\;\;in\;(-\frac{\pi}{2},\frac{\pi}{2}){\times}R,$$ where $u^+={\max}\{u,0\},\;{\epsilon}_1,\;{\epsilon}_2$ are small number and $h_1(x,t)$, $h_2(x,t)$ are bounded, ${\pi}$-periodic in t and even in x and t and ${\parallel} h_1{\parallel}={\parallel} h_2{\parallel}=1$. We first show that the system has a positive solution, and then prove the uniqueness by the contraction mapping principle on a Banach space

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.407-409
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• 2006

This paper presents the methods of designing the control circuits for a Class D amplifier to have a peak performance. The proposed approach is based on the three functional components - a carrier generator, a feedback circuit and a dead-time circuit. First the analog signal is applied to the controller, which outputs the 3 level PWM waveform. The controller used for this experiment is made of the operational amplifier and the logic circuit. The experimental results show that the control circuit performs with satisfaction and its output is proportional to input audio signal, providing a satisfactory 3 level PWM pattern. From this design methodology, by implementing a proposed control circuit we can achieve the efficient Class D amplifier using the half-bridge, full-bridge or push-pull topology at the output stage.

• KIEAE Journal
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• 제17권3호
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• pp.15-21
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• 2017

Purpose: "Building energy design standard" is used to limit the thermal transmittance of building in Korea. However, it only covers the insulation standard for each appropriate elements of a building, not the thermal performance of Junction thermal bridge of windows and doors installed in wall. Therefore in this study, we have evaluated the thermal performance of Junction thermal bridge depending on installation method and position of windows and provide it as design data. Method: We analyzed heat transfer of 4-Track sliding window and tilt & turn triple glazed window that are placed in the first class category on window energy efficiency rating using Window 7.4 and Therm 7.4. Result : First, linear thermal transmittance of 4-Track sliding window differs by 2.2 times or more depending of installation method and location. It is higher than the linear thermal transmittance, 0.01W/mK, proposed by Passivhaus. Second, linear thermal transmittance of Tilt & turn triple glazed window differs by 7.7 times or more depending of installation method and location. The average linear thermal transmittance was less than 0.01W /mK when windows were installed on the internal wall insulation by the fixed hardware attachment method. Third, the thermal losses of a window caused by a junction thermal bridge are inversely proportional to the window area and converge gradually as the area increased.

• Journal of applied mathematics & informatics
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• 제5권1호
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• pp.141-152
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• 1998

Based on the geometric representation an efficient al-gorithm is designed to find all articulation points of a permutation graph. The proposed algorithm takes only O(n log n) time and O(n) space where n represents the number of vertices. The proposed se-quential algorithm can easily be implemented in parallel which takes O(log n) time and O(n) processors on an EREW PRAM. These are the first known algorithms for the problem on this class of graph.

• 한국방재학회 논문집
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• 제10권5호
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• pp.35-40
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• 2010

본 연구에서는 RC슬래브 교량의 내하력을 향상시키기 위해 유리섬유 복합재(CAF)를 이용한 보강방법을 제시하였다. 보강 성능을 평가하기 위해 설계하중 DB 18로 설계된 실험대상 교량의 슬래브 하면에 단위폭당 50 cm로 CAF 복합재를 보강하여 정 동적재하시험을 수행하였다. 정 동적재하시험 결과 RC슬래브의 최대변위, 변형률, 충격계수는 보강전에 비하여 보강후에 각 14.7%, 5.0% 및 33.7% 감소하였다. 시험경간 중앙부에서의 RC슬래브의 공칭저항비는 27% 증가하였고, 공용내하력은 1,2 경간에서 44.6%, 48.9%증가하였다. 결론적으로 설계하중 DB 18로 설계된 노후된 RC슬래브 교량을 현행 1등급교의 설계하중 DB 24로 향상시키는데 CAF 복합재를 이용한 보강방법은 매우 효과적인 것으로 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.485-488
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• 2006

This research has evaluated flowability of ultra flowing self-compacting concrete, which is limitedly used for traditional building structures, in accordance with the first class regulations of Japan Society of Civil Engineering(JSCE) that can be applied to overcrowding-arrangement of bar, as a part of application methods that ultra flowing self-compacting concrete is applied to both precast and prestress bridge structures. The experimental results show that the flowability is acceptable in ternary blended among binary and ternary blended mixings, which satifies the first class regulation of JSCE. It is also concluded to use fly ash to increase viscosity of concrete in the case of segregation resistance because of low viscosity in the mixture of slag from blast furnace and limestone micropowder. Satisfying goals of every mixing after U-box self-compacting experiment, we conclude that ultra flowing self-compacting concrete is applicable to bridges and civil constructions of overcrowding arrangement of bar with evaluation of flowability of ultra flowing self-compacting concrete.

• Journal of Power Electronics
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• 제11권6호
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• pp.811-818
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• 2011

Modulation strategies for multilevel inverters have typically focused on synthesizing a desired set of sinusoidal voltage waveforms using a fixed number of dc voltage sources. This makes the average power drawn from different dc voltage sources unequal and time varying. Therefore, the dc voltage sources are unregulated and require that corrective control action be incorporated. In this paper, first two new selections are proposed for determining the dc voltage sources values for asymmetric cascaded multilevel inverters. Then two modulation strategies are proposed for the dc power balancing of these types of multilevel inverters. Using the charge balance control methods, the power drawn from all of the dc sources are balanced except for the dc source used in the first H-bridge. The proposed control methods are validated by simulation and experimental results on a single-phase 21-level inverter.