• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.300-301
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• 2017

태양광인버터는 MPPT 알고리즘, 계통연계 알고리즘 및 단독운전 알고리즘이 동시에 동작하고 있어 제어기를 설계하는데 있어 고려해야 하는 여러 가지 요소들이 존재한다. 태양광 인버터의 제어기를 설계하는 데 주요한 고려요소를 설명하고 제어기 설계 예를 보인다.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.627-636
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• 2005

The analysis and design procedure of intermediate support strut for the innovative prestressed scaffolding (IPS) system was presented in this paper. The stability check of intermediate support strut is required as the behavior of the strut system is similar to that of the built-up column. The computer analysis model of the support strut was constructed for in-plane and out-of-plane buckling analysis, and the design of the support strut was performed. Using the eigenvalue for the buckling load and the member forces of support strut under design earth pressure, the effective buckling length was estimated. The allowable axial and bending stresses were calculated considering the effective buckling length. The combined stresses due to these axial forces and bending moment were estimated to be satisfied the safety condition of the intermediate support strut.

• Land and Housing Review
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• v.5 no.2
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• pp.91-97
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• 2014

An experimental program was initiated to investigate the structural capacity of PC (Precast Concrete) beam-column joints used for the underground parking structure. Static testing of 4 typical PC beam-column joints specimens was conducted. Specimens were designed to span a range of parameters typically encountered for such members, based on findings from the survey of existing PC joint details used in the construction fields in Korea. The specimens were four by their joint types and testing parameters. The specific structural behavior germane to each specimen, and general observations on overall member behavior as a function of the considered parameters, are reported. From the results of tests on four PC joints specimens, the beam-column joints of PC structure used for the underground parking building was found to have similar structural capacities when comparing to the cast-in-place concrete system.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.78-86
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• 2003

Reinforced concrete beams are often retrofitted with various FRP composite sheets. This paper is focused on the comparison of structural performance of various FRP sheets and proposal of the retrofitting design formula. Effects of the FRP kinds(AFRP, GFRP, CFRP) and the reinforcing steel ratio on behavior of the retrofitting beams are tested and analyzed with particular emphasis on the maximum load capacity, stiffness, and ductility. The experimental work included 4 point flexural testing of 3.2m span reinforced concrete beams with bonded external reinforcements. The results show that the difference of FRP kinds is not large and the flexural load capacity is mainly affected by stiffness of the retrofitting materials. This paper also proposes the design formula on the retrofitting reinforced concrete flexural members and checks with this experimantal work and previous research results.

• Journal of Korea Water Resources Association
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• v.43 no.1
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• pp.41-49
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• 2010

Stepped weir of this study was suggested a type of natural type structures. Unique flow, such as Wave type flow, at downstream of mild slope stepped occurs. WTF(Wave type flow) is different with hydraulic jump occurred at Round crest weir. WTF is phenomenon to rise the water level by recirculation area occurred by step height at downstream of mild slope stepped. Wave height of WTF condition is higher than tailwater level and maximum velocity of WTF condition occurs in area of water surface. In this results, WTF presents to be important factor for design of join area of weir with levee. This study got and analyzed hydraulic condition occurred of WTF, scales of WTF and velocity profiles on flow patterns using experiments. WTF was not consider to stepped weir design and this results can be important data for design of stepped weir and structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.4
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• pp.11-22
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• 2023

In this study, a structural concrete square beam was developed using the centrifugal molding technique. In order to secure the bending stiffness of the cross section, the hollow rate of the cross section was set to 10% or less. Instead of using the current poor mixture of concrete, a special formwork for producing a centrifugal square beam was manufactured, and a concrete mixing ratio with a high slump (150-200) and a design strength of 100 MPa or more was developed and applied. The produced centrifugally formed rectangular beams were subjected to performance tests according to the standard bending and shear test standards for centrifugally formed members. The static load test results for the four specimens exceeded both the nominal bending strength and nominal shear strength, which are design values through structural design, proving the structural reliability of the ultra-high-strength centrifugally formed square beam.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.19-30
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• 2000

The major design parameters of the anchored sheet-pile wall include the determination of required penetration depth, the force acting on the anchor, and the maximum bending moment in the piling. Blum solved the fixed earth supported wall using the equivalent beam method, assuming that the wall can be separated into upper and lower parts of the point of contraflexure. Design charts help designer by simplifying the design procedure. But they have some difficulties under some Geotechnical and geometrical conditions. For example, the conventional design charts can compute design parameters only when the ground water table exists above the dredge line. In this paper, the design charts which can be used for the ground water table existing under the dredge line are presented. And simplified formulae are developed by regression analysis. It is found that simplified formulae are not only very useful for the practice of design but also they can evaluate the result of numerical methods or design charts.

• Journal of the Korea Concrete Institute
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• v.28 no.3
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• pp.267-278
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• 2016

In this study, the ultimate strength of 335 simply supported reinforced concrete beams with shear span-to-effective depth ratio of less than 3 was evaluated by the ACI 318-14's strut-tie model approach implemented with the indeterminate strut-tie models and load distribution ratios of the companion paper. The ultimate strength of the beams was also estimated by using the experimental shear strength models, the theoretical shear strength models, and the current strut-tie model design codes. The validity of the proposed strut-tie models and load distribution ratios was examined by comparing the strength analysis results classified according to the prime design variables of the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.279-289
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• 2003

Geosynthetic reinforced earth wall was introduced about 20 years ago and many structures have been constructed. Especially, segmental concrete panel facing and friction tie system are the most popular system in Korea, and this friction tie was composed of high tenacity PET filament and LDPE(Low Density Polyethylene) sheath. Due to the lack of direct-test results, design coefficients of friction tie (creep reduction factor) had been determined by quoting the previous and the foreign reference data. This is an unreasonable fact for the use of friction ties. In this study, the creep tests were performed to evaluate the creep behavior of friction tie, and the reduction factor of creep was calculated for the correct design of geosynthetic reinforced earth retaining walls. From the test results, finally it was found that the allowable creep strength of friction tie is 60% of Tult during service life, and creep reduction factor is 1.67 for each grade of friction ties.

• Journal of the Korea Concrete Institute
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• v.17 no.2 s.86
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• pp.213-220
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• 2005

Carbon fiber reinforced polymer (CFRP) sheets are becoming increasingly popular for strengthening deteriorated concrete bridges due to their excellent strength and stiffness-to-weight ratio, corrosion resistance, and convenience of construction work. The purpose of this study is to compare the performance of CFRP-strengthened reinforced concrete (RC) beams and to develop a new design formula. Simple beams with 3 m span length were tested to investigate the effect of reinforcing steel ratio and CFRP-reinforcing ratio on the flexural behavior of strengthened RC beams. The test results were analyzed with the special emphasis on the failure mode, the maximum load, and the strain distribution in the section. It is shown that the strain of the strengthened beams is not linearly distributed in the section. A new design formula based on the non-linear distribution of the strain has been derived and showed that it has a good agreement with the various domestic and foreign test results.