• Journal of the Korean Society for Precision Engineering
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• v.6 no.3
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• pp.100-108
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• 1989

The frequency equation and numerical process of natural frequencies for several boundary conditions of L-type folded plate given to the different thickness and lenth are derived by using Rayleigh-Ritz method in this study. Those natural frequencies are attaind by choosing the proper eigenfunction for boundary conditions of x-direction and y-direfction beams, by considering the convergence of numerical results.

• Journal of Korean Society of Steel Construction
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• v.30 no.1
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• pp.49-58
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• 2018

This study conducted nonlinear finite element analysis to figure out the influence of shear performance on the ${\beta}$ of girders with trapezoidal corrugated web. Through the experiment specimen, analysis model which is highly accurate was verified. Based on this, a parameter analysis was conducted on key variables affecting ${\beta}$. Proposed formulas of previous studies were analyzed using parameter analysis result. Eurocode was designed to be safer than other proposals. Only models that are included in the inelastic area, depending on the Moon's proposal, were satisfied the proposed formulas by Kim to enhance economic design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.126-136
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• 2018

A steel-plate concrete composite beam is composed of a steel plate, concrete and shear connector to combine inhomogeneous two materials. The steel plate is assembled by welding an existing composite beam. In this study, new steel-plate concrete composite beam, called a SPC Beam, was developed to reduce the shear connector and improve the workability. The SPC Beam was composed of folding steel plates and concrete, without a shear connector. The folding steel plate was assembled using high strength bolt instead of welding. To improve the workability in field construction, a hat-shaped Cap was attached to the junction with a slab. Monotonic load testing under two points was conducted under displacement control mode. The flexural strength of the specimen for positive moment and negative moment was calculated using the plastic stress distribution method. The test results showed that the flexural strength of the new SPC Beam had 80% of the strength of a complete composite beam. In addition, increasing the composite ratio was possible through clearance controls of the cap. In this study, the performance of the SPC Beam was verified through additional experiments and analyses with the cross-sectional shape and cap as variables, because the representative shape in the positive negative moment region is targeted.

• Journal of Korean Association for Spatial Structures
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• v.17 no.2
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• pp.4-7
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• 2017

• Journal of Energy Engineering
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• v.24 no.4
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• pp.105-116
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• 2015

In this study, airside performance of round fin-and-tube heat exchangers are compared with that of the herringbone wave fin-and-tube heat exchangers with an aim to investigate the effect of fin shape on thermal performance. Results show that j factors of the round wave fin are 1.2~22% larger than those of herringbone wave fin. The f factors of the round wave fin are -1.0~29% smaller than those of herringbone wave fin for 1 or 2 row configuration. For 3 row configuration, f factors of the round wave fin are 8.3~23% larger. The reason may be attributed to the reduced recirculation zone in the valley of the fin for round wave fin as compared with that of the herringbone wave fin. For round wave fin, the effect of fin pitch on j and f factor is not significant. In addition, j factors decrease as the number of tube row increases. On the other hand, f factors are independent of the number of tube row. A new correlation was developed based on the present data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.305-314
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• 2018

The steel-plate concrete composite beam is composed of a steel plate, concrete and a shear connector to combine the two inhomogeneous materials. In general, the steel plate is assembled by welding an existing composite beam. In this study, a new steel-plate concrete composite (SPCC) beam was developed to reduce the size of the shear connector and improve its workability. The SPCC beam was composed of folded steel plates and concrete, without any shear connector. The folded steel plate was assembled with high strength bolts instead of welding. To improve the workability in field construction, a hat-shaped cap was attached in the junction with the slab. Monotonic two-point load testing was conducted under displacement control mode. The flexural strength of the SPCC beam specimen was calculated to be 76% of that of the complete composite beam by using the plastic stress distribution method and strain compatibility method. The cap acted as the stud and accessory. The synthesis rate could be increased by controlling the gap of the cap, and the bending performance could be evaluated by using the strain fitting method considering the synthesis rate of the SPCC beam.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.209-212
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• 2008

Corrugated steel-concrete composite deck with I-beam welded is lighter and has higher load carrying capacity than RC slabs due to an I-beam embedded in the corrugated deck. The methods suggested from ACI and design standard of roadway bridge are used to evaluate effective moment inertia of RC structures. This paper presents evaluation and application of effective moment inertia for corrugated steel-concrete composite deck with I-beam welded by using the methods suggested from design standard of roadway bridge, ACI and CEB-FIP MC-90. In order to evaluate effective moment inertia, a series of flexural experiments were carried out. Five beams were built and the parameters considered in the experiments were studs, shape of the sections and connections of the beams. By using the aforementioned methods, effective moments of inertia was calculated and they were compared with the experimental results. As a result, The method suggested from CEB-FIP MC-90 yielded more satisfactory agreement than that from ACI. It was found that the beam has studs showed high load-carrying capacity and high effective moment of inertia.

• Journal of Korea Water Resources Association
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• v.35 no.2
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• pp.231-240
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• 2002

The wetland has very important functions in hydrologic and ecological aspects and the research of wetland functions requires the basic hydrological properties such as water quantity. However, we do not have a research work on the hydrological properties for a wetland study in Korea. Therefore, this study is to estimate the relations between the volume(V), the area(A), and the depth(h) of water in the wetland which might be the basis for the wetland research in Korea. To estimate the relations, we derive the basic equations, obtain the surveyed data and do modelling, and estimate the relations of A-h and V-h using the Surfer program. The estimated and observed volumes for 5-wetland are compared and the errors are in the range of 2 % to 11 % for 4-wetland and 34 % for the rest. The wetlands in small errors showed the similar ones with the profile of the wetted perimeter which is assumed for the derivation of the equation but the wetland of large error has much different profile with the assumed one. We re-estimate the volumes for 3-wetland(W3, W4, W5) which showed the large errors due to the bended profiles of the wetland slopes. say, after the slopes was divided into two parts of upper and lower ones, the volumes were estimated. From our re-estimation, we obtained very good results ranged from 1 % to 8 % in their errors. We conjecture that the procedure suggested in this study might be useful as a reference for the future research on the relations of V-A-h in Korea.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.96-100
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• 2001

본 논문에서는 skeleton slot 복사기를 이용하여 GSM 900과 GSM 1800에서 사용할 수 있는 이중대역 안테나를 설계 및 제작하여 측정 결과를 비교 분서하였다. 기본적인 skeleton slot 구조에서는 낮은 밴드의 2배 이상의 주파수에서는 수평 빔폭이 일정치 않고, 정재파비 특성이 불량하였으나, 급전부와 측면 방사부분의 다중경로 형성 및 절곡 구조를 이용하여 이를 해결하였다. 안테나의 크기는 반사판이 190$\times$190(mm), 복사기는 154$\times$106(mm), 높이는 33mm로 하여 현재 서비스 사업자틀이 주로 사용하는 크기로 구성하였다. 구성 재질은 1mm 두께의 알류미늄판을 이용하며, 이를 NCT로 타공 및 절곡하여 제작하였기 때문에 대량 생산 시 단가를 낮출수 있다. 실측결과 900MHz 대역에서 13.7%, 1800MHz 대역에서 16.4%의 -l0dB 반사손실 대역폭을 만족하고, 방사패턴도 대역별로 $\pm$1$^{\circ}$이내의 일정한 양상을 보여 이중대역 안테나로서의 요구를 만족하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.36-44
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• 2019

The purpose of this study is to evaluate the structural performance of press-formed type asymmetric column to beam connections of steel-PC composite module frames. Most of the column sections of the joints making up the modular frame use a closed square steel section. The column-beam connection using the closed column section has difficulty in reducing the workability and securing the fire resistance. In order to overcome this disadvantage, concrete is filled in the asymmetrical open type cross section of the steel plate by press forming. A total of four specimens were fabricated to investigate the structural performance of press formed type asymmetric column to beam connections. The experimental results show that the structural performance and behavior of the asymmetric columns are different depending on whether the asymmetric column cross section is composited or the column width thickness ratio. The structural performance of the press formed type asymmetric column to beam connection was evaluated by comparing the experimental results with the theoretical formulas.