• 기술발표회
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• s.2006
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• pp.35-44
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• 2006

Supporting method of a Temporary retaining wall for underground excavation project are adopted by systems of strut, anchor, nail, raker, etc. Strut system and Raker system of these methods are mostly used preloading jack to minimize deformations of retaining wall. We determinate efficient preloading to analysis these strut-preloadings, deformations of retaining wall, axial forces, and etc.. This study is analysed that preloading applied 0%, 10%, 20%, 30%, ...., 100% for strut and raker installed by CIP temporary retaining wall. This study results that adequate preloadings were determined to analysis correlations of preloading, deformations of wall, maximum bending moment, axial force of strut, and displacement of surrounding.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.5
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• pp.801-813
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• 2017

Passive force acting on the kicker block used to support a raker is different dependent on soil's type. The passive force incorporating a factor of safety is considered for design of the retaining wall. However, an actual passive force developing on the kicker block is overestimated and it may lead to an unsafe design. In this study, the actual passive forces acting on the kicker block in soil ground are evaluated using 3-D Finite Element Program, PLAXIS. Soft and weathered soils are selected as a soil ground. The relation curves between horizontal displacement and actual passive force of the kicker block for each soil ground are obtained through numerical analyses. From the curves, the actual passive forces are determined as a yielding point, which are about 55.5% and 66% of Rankine's passive forces in soft and weathered soils, respectively.

• Applied Microscopy
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• v.39 no.4
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• pp.319-324
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• 2009

Morphology of the gill in Lateolabrax japonicus was investigated after staining the gill, as a result, we found the gill is composed of gill raker, gill arch, gill filament and gill lamellae. The number of gill raker was 7~10 in the upper and 13~18 in the lower. Ultrastructure of the gill in Lateolabrax japonicus were examined by means of the light and transmission electron microscopes. The gill have primary filament and secondary filament (lamellae). The following cells are identified and described: pavement cell, pillar cell, blood cell, mucose cell and chloride cell etc. Simple epithelial layer consists of squamous epithelium contained large nucleus, intracellular organelles etc. and the surface is covered with some of microridges. The lamella pillar structures are characterized by the axial microtubules and lateral membrane interdigitations. The mucous cells were globular in shape, and had almost the mucous granules of same size with various electron density. Chloride cells contain a lot of mitochondria and specifically developed tubular systems.

• Korean Journal of Environmental Biology
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• v.39 no.1
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• pp.6-15
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• 2021

Various biometric and geometric measures were used to discriminate between the morphologically similar river puffer, Takifugu obscurus, tiger puffer, T. rubripes, their hybrids, and their triploid hybrids. The hybrids and triploid hybrids had greater anal fin width, nostril width, and snout length than the parental species (p<0.05). However, they had less caudal peduncle depth, inter-orbital width, head length, and head width(p<0.05). The morphometric and meristic characteristics of the hybrids and triploid hybrids were either intermediate between the parental species or more similar to those of one parental species. However, the external morphology of the hybrids and triploid hybrids was predominantly maternal. The triploid hybrids had asymmetry in the fin rays and gill raker numbers. This study identified phenotypic characteristics by distinguishing the morphological variables of river puffer, tiger puffer, their hybrids, and their triploid hybrids.

• Korean Journal of Ichthyology
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• v.22 no.2
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• pp.132-135
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• 2010

A specimen of Arnoglossus polyspilus (G$\ddot{u}$nther) (229.0 mm standard length) belonging to the family Bothidae, collect from the coastal waters of Jeju Island, represents the first record of the species from Korea. This species is characterized by having caudal fin with two simple rays on both upper and lower margins, several anterior dorsal fin rays somewhat elongated, upper jaw extending to below anterior 1/3 of lower eye, and one gill raker on the upper limb of the first gill arch. We add this species to the Korean fish fauna and propose its new Korean name, "No-rang-ban-jeom-ga-ja-mi".

• Korean Journal of Ichthyology
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• v.13 no.3
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• pp.190-194
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• 2001

Two specimens of Sardinella lemuru Bleeker, 1853 were collected for the first time from the adjacent waters of Cheju Island, Korea, in March 1997. S. lemuru is very similar to S. zunasi (Bleeker, 1854) in external features but differs in the number of anal fin rays. While S. lemuru is difficult to differentiate by color from Clupea pallasii valenciennes, 1847 the two are easily differentiated by their gill raker counts. We propose "Bali-paen-dang-i" as a new Korean name for S. lemuru.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.5
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• pp.145-152
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• 1998

In this research, in order to predict the cutting force using a mechanistic model, specific cutting force was firstly obtained through the cutting experiments. Band sawing process is similar to a milling, that is multi-point cutting. Therefore it is not easy matter to evaluate specific cutting force. Thus, the thickness of workpiec was made smaller than one pitch of the saw in terms of fly cutting in the face milling process. Then the cutting force was predicted by analyzing the geometric shape of a saw tooth The tooth shape used in the research was raker set style that was generally used in band sawing. And a set of teeth is comprised of three teeth, those are ranked as left, straight and right. The mechanistic model was developed in this study considered those shapes of each tooth. From the validation experiments, the predicted cutting forces coincided well with the measured ones. Therefore the predicted cutting forces can be used for the adaptive control of saw engaging feed rate in the band sawing.

• Korean Journal of Ichthyology
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• v.17 no.1
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• pp.57-63
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• 2005

The digestive apparatus and food of the Korean bitterling, Acheilognathus signifer, from the upper reaches of the Hongcheon River were investigated by examining their gill rakers, pharyngeal teeth, and digestive-tube contents. Gill rakers of the first arch were relatively few (17 to 21, mean = 19) and short (mean = 0.36 mm, SD = 0.035). The 2nd to 5th pharyngeal teeth were well developed, while the first tooth was poorly developed. Gill rakers and pharyngeal teeth were completely formed early in life. The digestive tube was long and arranged in many coils. The digestive-tube contents of Korean bitterling mainly consisted of phytoplankton and detrital microorganisms.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.51-60
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• 2020

Estimation of passive earth pressure is an important factor in anchor block, temporary retaining wall and support block of raker that resist lateral earth pressure. In practice, due to ease of use, it is common to estimate the earth pressure using the theory of Coulomb and Rankine, which assumes the failure plane as a straight line. However, the passive failure plane generated by friction between the wall surface and the soil forms a complex failure plane: a curve near the wall and a flat plane near the ground surface. In addition, the limit displacement where passive earth pressure is generated is larger compared to where the active earth pressure is generated. Thus, it is essential to calculate the passive earth pressure that occurs at the allowable displacement range in order to apply the passive earth pressure to the design for structural stability reasons. This study analyzed the mobilized passive earth pressured to various displacement ranges within the passive limit displacement range using the semi-empirical method considering the complex failure plane.

• Geomechanics and Engineering
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• v.15 no.5
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• pp.1061-1070
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• 2018

The main purpose of retaining wall methods for deep excavation is to keep the construction site safe from the earth pressure acting on the backfill during the construction period. Currently used retaining wall methods include the common strut method, anchor method, slurry wall method, and raker method. However, these methods have drawbacks such as reduced workspace and intrusion into private property, and thus, efforts are being made to improve them. The most advanced retaining wall method is the prestressed wale system, so far, in which a load corresponding to the earth pressure is applied to the wale by using the tension of a prestressed (PS) strand wire. This system affords advantages such as providing sufficient workspace by lengthening the strut interval and minimizing intrusion into private properties adjacent to the site. However, this system cannot control the tension of the PS strand wire, and thus, it cannot actively cope with changes in the earth pressure due to excavation. This study conducts a preliminary numerical analysis of the field applicability of the controllable prestressed wale system (CPWS) which can adjust the tension of the PS strand wire. For the analysis, back analysis was conducted through two-dimensional (2D) and three-dimensional (3D) numerical analyses based on the field measurement data of the typical strut method, and then, the field applicability of CPWS was examined by comparing the lateral deflection of the wall and adjacent ground surface settlements under the same conditions. In addition, the displacement and settlement of the wall were predicted through numerical analysis while the prestress force of CPWS was varied, and the structural stability was analysed through load tests on model specimens.