• Proceedings of the Korean Geotechical Society Conference
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• 1997.10a
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• pp.141-150
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• 1997

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.72-73
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• 2012

• Animal cells and systems
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• v.1 no.2
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• pp.371-379
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• 1997

To investigate the movement of sperm head and the role of sperm neck in forward sperm motility in the Korean striped field mouse, Apodemus agrarius coreae, the morphological characteristics of the cauda epididymal spermatozoa were examined by light microscopy and scanning and transmission electron microscopy. Spermatozoa of A. agrarius coreae were characterized by the conspicuous shape of the acrosome and the long tail compared with those of other rodents. Total length of the sperm was $133\mu{m}$. The sperm head had a curved falciform shape. The head was 8.0${\mu}$m in length, and about 4.0 ${\mu}$m in width. The shape of acrosome had an openerlike form. The sperm tail (125 ${\mu}$m) consisted of four major segments: neck (0.5 ${\mu}$m), middle piece (29.5 ${\mu}$m), and principal piece plus the end piece (95 ${\mu}$m). The outer dense fibers were arranged in a horseshoe fashion, and No. 1, 5, 6, and 9 of the outer dense fibers were larger than the others. The mitochondrial bundles of middle piece were composed of a pair of arms, which surrounded the axone of the middle piece by the 45 0 angled helical structure. The total number of mitochondrial gyres was 188. In particular, the microfilament structures existed in plasma membrane of the sperm, which was adjacent to the acrosomal region on the nuclear membrane. The segmented columns were surrounded by microfilament structures, and the microfilament bundles were adjacent to the outer membrane of the first mitochondria of middle piece. This study presents for the first time the existence of microfilament structures within the plasma membrane of sperm which is located from the adjacent acrosome region to the connecting piece in sperm neck of Korean striped field mouse, Apodemus agrarius coreae. The present result suggests that the constriction and extension of microfilament in sperm neck as well as the wave-movement of sperm tail may play a role in the movement of sperm head.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.81-88
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• 2017

This study deals with the optimal design of a hybrid control system composed of a combination of active control system and passive control system for effective seismic performance improvement of two adjacent structures. The proposed hybrid control system adopts a configuration of installing an active control device in one building and connecting two adjacent structures with a passive control device so that the one-side active control force can be bi-directionally applied to both buildings through the passive connecting devices. In order to derive the optimal performance of the proposed system, the design parameters of the passive and active control systems were searched using the genetic algorithm. Numerical simulations of 10-story and 8-story buildings have been performed to verify the effectiveness of the proposed technique. For the purpose of comparison, the conventional independent control system with two identical active control systems being installed separately for each structure was also optimally designed and its seismic response has been evaluated as well. From the comparative results of the two control systems, it is demonstrated that the proposed hybrid control system requires larger control force for its one-side active control device than the conventional independent control system does for each of both-side active devices, but quite less than the total control force required for both-side devices of the independent control system, while maintaining similar seismic performance. Therefore, the proposed system is more economical and reliable than the conventional independent control system with two identical active devices.

• Tunnel and Underground Space
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• v.34 no.3
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• pp.196-207
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• 2024

In this study, a comprehensive management plan was proposed to ensure the stability of the existing subway when constructing ground structures adjacent to the subway. In the first step, the measurement inspection cycle is selected through proximity evaluation, in the second step, the stability of existing subway and station structures such as displacement and stress is reviewed through 3D numerical analysis considering the construction stage and groundwater influence, and in the third stage, the safety of train operation was reviewed by examining the track stability, and based on the numerical analysis results in the fourth stage, the displacement concentration section was selected as an intensive management section and it was proposed that intensive measurement management be performed.

• Structural Engineering and Mechanics
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• v.13 no.5
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• pp.465-478
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• 2002

This study lays emphasis on the development of efficient analytical models for a multistory structure with wings, including the in-plane deformation of floor slabs. For this purpose, a multistory structure with wings is regarded as the combination of multistory structures with rectangular plan and their junctions. In addition, a multistory structure with a rectangular plan is considered to be an assemblage of two-dimensional frames and floor slabs connecting two adjacent frames at each floor level. This modeling, concept can be easily applied to multistory structures with plans in the shape of L, T, Y, U, H, etc. To represent the in-plane deformation of floor slabs efficiently, a two-dimensional frame and the floor slab connecting two adjacent frames at each floor level are modeled as a stick model with two degrees of freedom per floor and a stiff beam with shear deformations, respectively. Three models are used to investigate the effect of in-plane deformation of the floor slab at the junction of wings on the seismic behavior of structures. Based on the comparison of dynamic analysis results obtained using the proposed models and three-dimensional finite element models, it could be concluded that the proposed models can be used as an efficient tool for an approximate analysis of a multistory structure with wings.

• Imaging Science in Dentistry
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• v.52 no.4
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• pp.343-350
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• 2022

Purpose: This study evaluated the prevalence of dental implant positioning errors and the most frequently affected oral regions. Materials and Methods: A sample was obtained of CBCT images of 590 dental implants from 230 individuals who underwent diagnosis at a radiology center using cone-beam computed tomography from 2017 to 2020. The following variables were considered: thread exposure, violation of the minimum distance between 2 adjacent implants and between the implant and tooth, and implant contact with anatomical structures. Descriptive data analysis and the Pearson chi-square test(P<0.05) were performed to compare findings according to mouth regions. Results: Most (74.4%) of the 590 implants were poorly positioned, with the posterior region of the maxilla being the region most frequently affected by errors. Among the variables analyzed, the most prevalent was thread exposure (54.7%), followed by implant contact with anatomical structures, violation of the recommended distance between 2 implants and violation of the recommended distance between the implant and teeth. Thread exposure was significantly associated with the anterior region of the mandible (P<0.05). The anterior region of the maxilla was associated with violation of the recommended tooth-implant distance (P<0.05) and the recommended distance between 2 adjacent implants(P<0.05). Implant contact with anatomical structures was significantly more likely to occur in the posterior region of the maxilla (P<0.05). Conclusion: Many implants were poorly positioned in the posterior region of the maxilla. Thread exposure was particularly frequent and was significantly associated with the anterior region of the mandible.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.3052-3060
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• 2013

When planning to construct adjacent structure by the side tunnel, the criteria of safety zone of tunnel have been proposed. There are no specific theoretical basis regarding load conditions and the distance of structure and the geological strata and the conditions of adjacent structure's location, and the conditions applied load. Two and three dimensional numerical analysis preformed to prove the deformation of the ground and structures caused by the tunnel excavation and evaluated the correlation and the suitability of the tunnel's safety zone regarding the location of adjacent structures and the changes in the modulus of deformation. This paper proposed the safety zone's range is getting bigger as the modulus of deformation is higher. Also, it seems that the possible range of construction under constraints in the diagram of revalued safety zone significantly expands as shear failure line appears on the invert extension line below the spring line.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.579-584
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• 2024

Currently, large-scale, deep construction is being carried out adjacent to subway tracks in korea. when excavating adjacent to each other, it is very important to ensure the safety of earth retaining structures and underground structures. therefore, we are managing the safety of the subway by introducing an automated measurement system. deformation of the subway track during adjacent excavation may affect train running stability. this is a factor that can be linked to train derailments. however, current subway track safety evaluation using automated measurement systems relies only on the maximum value of measured data. therefore, a method to improve the usability of automated measurement system results is needed. in this study, we utilized a technique that can quantitatively evaluate the measurement results of a large amount of subway track deformation. a safety evaluation was conducted on subway track deformation due to adjacent excavation using a vast amount of data using probabilistic statistical analysis techniques.

• Korean Journal of Environmental Agriculture
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• v.28 no.4
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• pp.340-346
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• 2009

Chromated copper arsenate (CCA) is a chemical wood preservative that has been intensively used to protect wood from decay during the last few decades. CCA is widely used to build structures such as decks, fences, playgrounds and boardwalks. However, structures constructed of CCA-treated wood have caused adverse environmental effects due to leaching of Cr, Cu and As into surrounding soils. This research was conducted to monitor the vertical and horizontal distribution of Cr, Cu and As in soils adjacent to CCA-treated wood structures in Korea. Two structures constructed with CCA-treated wood were selected at Hongcheon and Chuncheon in Gangwon Province, South Korea. Eleven soil profile samples were collected at depths of 0 to 80 cm at each site, while 12 surface soil samples were collected at distances of 0 to 200 cm from each structure. The soil chemical properties, soil particle size distribution and total metal concentrations were then determined. The results revealed that soils near CCA-treated wood structures were generally contaminated with Cr, Cu and As when compared to the background concentration of each metal. In addition, the concentrations of Cr, Cu and As in soils decreased as the vertical and horizontal distance from the structure increased. Further studies should be conducted to evaluate the mobility and distribution of these metals in the environment as well as to develop novel technologies for remediation of CCA contaminated soils.