• Composites Research
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• v.32 no.2
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• pp.108-112
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• 2019

There has been a continuous study on the weight reduction of structure by composites. Unlike isotropic materials, the physical properties of composites vary according to the direction of laminate and the order of lamination. Therefore, in the case of composite ladders, it is essential to perform structural analysis to verify the planned design. In this study, ladder was designed by applying fabric material. In addition, the effect of loading position on the ladder was analyzed through finite element analysis, and structural performance was analyzed by selecting the most problematic location. We analyzed the effect of stacking order on the structural strength of the ladder by analyzing the structure by applying various stacking sequence and measuring the failure value in each layer.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.671-676
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• 2001

Reinforcement corrosion is major problem for those who own and maintain reinforced concrete structures exposed to chlorides. It is well understood that the form of corrosion is more problematic than corrosion found elsewhere, Because concrete has no apparent signs that there is anything amiss until the process of deterioration is relatively far advanced. The objective of this research is to develop the ladder system which monitors the corrosion of reinforcing steels in concrete. This system can be used to assess the corrosion condition and corrosion rate of steel in concrete, which can give timely repair and strengthening of steel in concrete structure.

• Journal of Species Research
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• v.9 no.2
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• pp.147-161
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• 2020

Seven new species of two genera Scalarispongia and Smenospongia (Demospongiae: Dictyoceratida: Thorectidae) are described from Gageo Island and Jeju Island, Korea. Five new species of Scalarispongia are compared to nine reported species of the genus by the skeletal structure. Scalarispongia viridis n. sp. has regular ladder-like skeletal pattern arranged throughout the sponge body and has pseudo-tertiary fibres. Scalarispongia favus n. sp. is characterized by the honeycomb shape of the surface and is similar to Sc. flava in skeletal structure, but differs in sponge shape. Scalarispongia lenis n. sp. is similar to Sc. regularis in skeletal structure but has fibers that are smaller in size. Scalarispongia canus n. sp. has irregular skeletal structure in three dimensions and ladder-like which comes out of the surface and choanosome. Scalarispongia subjiensis n. sp. has pseudo-tertiary fibres and its regular ladder-like skeletal pattern occurs at the choanosome. Two new species of Smenospongia are distinguished from the other 19 reported species of the genus by the skeletal structure. Smenospongia aspera n. sp. is similar to Sm. coreana in sponge shape but new species has rarely secondary web and thin and thick bridged fibres at near surface. Smenospongia mureungensis n. sp. has very simple skeletal structure.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.630-632
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• 2003

In this paper, we present the fabrication and performance of FBAR filters with ladder and stacked crystal filter (SCF) types. The structure of the unit resonator in our work is the solidly mounted resonator (SMR) with W/SiO$_2$ multi-layer reflectors, the return loss of of which show -24dB at resonant frequency of -2.0GHz. The $K^2$eff, Q$_{s}$, and Q$_{p}$, indicating the performance of resonator were 3.24%, 6,363 and 6,749 and were calculated for the resonator with the resonance area of 21200${\mu}{\textrm}{m}$$^2$. Based on this unit resonator, FBAR filters with ladder and SCF types were fabricated and compared. The sizes of filters were 800$\times$2000(${\mu}{\textrm}{m}$$^2$) for the ladder type and 600$\times$500(${\mu}{\textrm}{m}$$^2$) for the SCF type.e..

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.721-726
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• 1999

The fishways on Namdae-cheon and Osib-cheon and the use of migratory fishes were investifated from July 1998 through Jung 1999. There are three types of fishways on these rivers. Those are baffled fishways, fish ladder, and fish ladder with gabion. Namdae-cheon has 7 baffled fishways and 19 fish ladder, and Osib-cheon has only fish ladder with gaboin. On Namdae-cheon 1,195 fishes of 24 species were collected. Amog these fishes 241 fishes of 9 species were anadromous fishes occupying 38% in species and 19% in number. On Osib-cheon 1,015 fishes of 24 species were collected. Among these fishes 240 fishes of 5 species were anadromous fishes occupying 21% in species and 24% in number. On Namdae-cheon the species number and auundance decreased gradually upstream. The poor structure of fishways seems to have worked as an obstacle to the upstream migration of fishes on Namdae-cheon. On Osib-cheon all the observed fish species except three -spined stickleback(Gasterosteus aculeatus aculeatus) which stay and spawn around downstream of river could migrate upstream. The good structure of fishways on this river is thought to have helped upstream fish migration.

• Analytical Science and Technology
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• v.20 no.4
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• pp.355-360
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• 2007

The title complex, $(C_3H_{12}N_2)[\{Cd(H_2O)(C_6H_5O_7)\}_2]{\cdot}6H_2O$, I, has been prepared and its structure characterized by FT-IR, EDS, elemental analysis, ICP-AES, and X-ray single crystallography. It is triclinic system, $P{\bar{1}}$ space group with a = 10.236(2), b = 11.318(2), c = $13.198(2){\AA}$, ${\alpha}=77.95(1)^{\circ}$, ${\beta}=68.10(1)^{\circ}$, ${\gamma}=78.12(1)^{\circ}$, V = $1373.5(3){\AA}^3$, Z = 2. Complex I has constituted by protonated 1,3-diaminopropane cations, citrate coordinated cadmium(II) anions, and free water molecules. The central cadmium atoms have a capped trigonal prism geometry by seven coordination with six oxygen atoms of three different citrate ligands and one water molecule. Citrate ligands are bridged to three different cadmium atoms. Each cadmium atom is linked by carboxylate and hydroxyl groups of citrate ligand to construct an one-dimensional ladder-type assembly structure. The polymeric crystal structure is stabilized by three-dimensional networks of the intermolecular O-H${\cdots}$O and N-H${\cdots}$O hydrogen-bonding interaction.

• Journal of the Korean Society of Safety
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• v.28 no.4
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• pp.66-71
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• 2013

There is a critically structural problem of scaffolding system when one of scaffold columns is remove to be used as a gangway for their temporary office in the structure before finishing all such as an apartment or office building. This is not used to checking to structurally checking at a construction site. This study is to find out which system at a site will be more effective and low-cost-high effectiveness of aluminum ladder, timber ladder, ${\phi}$1/2 inch steel pipe truss with a type of concave, convex warren truss ladders. Theses are structurally tested with horizontal set as a truss type with 1.8 meter long. Concentrated load has been loaded at the upper center of the system and checked its strain at the bottom center, using aluminum-use strain gage and steel-use gauge have been attached concave warren truss with diameter 1/2 inch has 14% stronger than convex truss. Convex truss has almost same strength as an aluminum ladder truss, it is found out.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.6
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• pp.1-8
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• 1982

In this paper a new analytic method for Ladder networks by weighted tree is proposed. In contrast to conventional tree concept that represents only information structure, in this paper, a tree with hierarchical structure is established by giving wei체t of impedance Z and admittance Y to branch and representing each node of its branch as a pair of voltage and current. Then, by defining generation level from tree structure and by parsing between standand level and arbitrary level, driving point impedance, transfer function and transfer impedance are simultaneously obtained instead of complex calculation method by inspection. The validity of this method is proved by the reciprocal theorem and this method is applied to four-terminal constants and the feedback network.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.245-248
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• 2001

In this paper, we have investigated the design technique and fabricated the surface acoustic wave (SAW) filter for duplexer, which consists of Tx. and Rx. filter, and antenna terminal. For Tx. and Rx. bandpass filters we used the one-port SAW resonators with n-section ladder structure. The structure is composed of couples of series-arm resonators and parallel-arm resonators. RF filter using ladder structure was designed and fabricated on 36$^{\circ}$Y-X LiTaO$_3$ substrates. Designed filters, insertion loss is less than 1.5dB, the bandwidth is more than 25MHz, rejection band level is less than -30dB and center frequency is 820MHz.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.8
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• pp.20-30
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• 1994

The lossless bounded real(LBR) two-pair cascade structure is one of the exiting low-sensitivity digital filter structures such as wave digital filters(WDFs) orthogonal filters. They are known to have the same structures which are composed of canonic building blocks interconnected to each other. The LBR two-pair cascade filters amount to describing in a unified manner the existing canonic low-sensitivity filters in terms of transfer matrices and chain matrices. However the existing structures have somewhat degraded low-sensitivity performance because they include dependent parameters within their structures. In this paper we propose a filter structure called “two-type-interlaced(TTI) structure.” eliminating such problem completely. This structures can be viewed as the WDFs of analog ladder circuits. As ladder circuits are obtained by cascading Brune sections and merging neighboring inductors or capacitors. so TTI structures at e obtained by cascading Type 3 LBR two-pairs and merging neighboring Type 1 LBR two-pairs. Next, a test procedure called “LBR test” is also presented in this paper. which determines whether of not the quantized TTI structure is stable . If it is unstable we can fine-tune the quantized parameters to make the overall structure stable. Therefore we can solve the dependent parameter problem completely with TTI structure along with LBR test. test.