• Structural Engineering and Mechanics
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• v.78 no.4
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• pp.425-437
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• 2021

Under foundation shock mats have been used in the current practice in order to reduce/damp vibrations received by buildings through the surrounding environment. Although some investigations have been made on under foundation shock mats performance, their effectiveness in the reduction of railway induced-vibrations has not been fully studied, particularly with the consideration of underneath soil media. In this regard, this research is aimed at investigating performance of shock mat used beneath building foundation for reduction of railway induced-vibrations, taking into account soil-structure interaction. For this purpose, a 2D finite/infinite element model of a building and its surrounding soil media was developed. It includes an elastic soil media, a railway embankment, a shock mat, and the building. The model results were validated using an analytical solution reported in the literature. The performance of shock mats was examined by an extensive parametric analysis on the soil type, bedding modulus of shock mat and dominant excitation frequency. The results obtained indicated that although the shock mat can substantially reduce the building vibrations, its performance is significantly influenced by its underneath soil media. The softer the soil, the lower the shock mat efficiency. Also, as the train excitation frequency increases, a better performance of shock-mats is observed. A simplified model/method was developed for prediction of shock mat effectiveness in reduction of railway-induced vibrations, making use of the results obtained.

• Journal of the Korea Safety Management & Science
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• v.21 no.3
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• pp.17-21
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• 2019

With the development of public transportation, the use of subways as a means of transportation in the city center is increasing, so that vibrations and structural noises are emerging as a new environmental issues. This study can be used as a basis for research on subway safety and shock mitigation by applying vibration-proof mat.

• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.44-51
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• 2010

A lab-scale apparatus for turbid water transport control was tested and examined. The channel had a dimension of $100cm{\times}30cm{\times}15cm$ (length${\times}$hight${\times}$width). And the turbidity water was prepared using two types of particles, bentonite and loess. The channel equipped with filamentous mat was operated under various shock load conditions. In the control channel, instantly, turbid water mixed with the clean water inside the channel and turbidity prevails the entire channel. While in the mat-equipped channel, it increases only at the bottom. Overall, the filamentous mat gave capture efficiency of 70~90% compared with the control group. The capture efficiency of turbid particles decreased with increased input turbidity flux. The result of experimental run on how turbid particles are separated in the mat channel shows that settling, filtration and attachment are the main processes. Meanwhile, turbidity was diffused from the channel bottom due to turbidity gradient before and after mat zone. The particle size before mat zone was lightly coarser than that after mat zone.

• Composites Research
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• v.32 no.5
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• pp.290-295
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• 2019

In the present study, composite insulation mat was reinforced over polyurethane foam (PUF) to improve the thermal performance and impact resistance of the PUF applied to the liquefied natural gas carrier insulation system. The composite insulation mat used Kevlar, aerogel, and cryogel composite mat that can be applied in a cryogenic environment. The thermal conductivity was measured at $20^{\circ}C$ to investigate the thermal performance, and the drop impact test was carried out under impact energy of 30 J at $20^{\circ}C$, $-163^{\circ}C$ to investigate the impact resistance. The measured thermal performance was compared with neat PUF through effective thermal conductivity theoretical value. The shock resistance was evaluated of contact force, contact time, and absorb energy. In experimental results, cryogel composite mat was the best performance in terms of thermal performance, and aerogel composite mat was the best performance in terms of impact resistance.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.502-504
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• 2001

본 논문은 동작자가 표현하는 수화 동작 중, 지문자 영상을 2차원 영상처리에 의하여 이식하는 방법을 제안한다. 손에 개인에 따라 변량이 존재하고 같은 동작을 표현하더라도 항상 일정하지 않기 때문에, 지문자 인식을 위하여 손의 구조적인 정보를 이용한다. 추출된 손 영역을 입력으로 하여 손의 외곽 정보를 이용한 MAT(Medial Axis Transform)를 수행한다. 여기에서 나온 골격의 변화에 따라 각각 손가락에 해당하는 2번 쇽(Shock)과 손 바닥에 해당하는 4번 쇽의 관계에 의하여 지문자를 인식한다. 이러한 구조적인 정보를 이용함으로써 개인에 의해 나타나는 표현의 차이를 제거할 수 있고, MAT를 이용할 때 나타나는 외곽영역의 잡음에 의한 구조 변화에도 안정적으로 대처할 수 있다. 제안한 알고리즘을 이용하여 31개의 단순 지문자에 대한 270개의 입력영상을 실험한 결과 81.1%, 모양이 흡사한 지문자를 통합하여 26개의 지문자로 식별할 경우에는 91.1%의 인식율을 나타내었다.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1250-1255
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• 2010

In this study, in order to examine the hydraulic characteristics for a crushed stone mat. it was accomplished discharge capacity test and soil-water characteristic curve(SWCC) with the object of the research. From the test result, it produced propriety mixed ratio of the crushed stone which mixes the sand. at the time of crushed stone 100% where it does not mixes the sand it appeared that permeability was biggest. increase of shock and content of the sand showed decrease of air entry value.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.3
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• pp.331-341
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• 2018

This study proposes an integrated serial spring-damper mechanism as a dual pulse generation system. Compared to the traditional dual pulse generation system, which used multiple springs and a damper to generate a dual pulse critical for impact testing of naval equipments, currently used separated serial spring-damper mechanism is comprised of two components: an air spring, and a damper. The proposed mechanism combines the two components into one integrated system with a unique design that lets simply changing the volume and the pressure of the air tank, and the length of the annular pipe adjust the stiffness and damping constants for testing, eliminating the need to have multiple sets of air springs and dampers. Simulations using MatLab and Simulink were conducted to verify the feasibility of this design. The results show the potential of an integrated serial spring-damper mechanism as a more convenient and flexible mechanism for dual pulse generation system.

• Korean Journal of Applied Biomechanics
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• v.14 no.3
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• pp.203-218
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• 2004

The purpose of this study was to analyze the comparisons of the kinematical variables when performing Yoko Ukemi(side breakfall) by three Stage in Judo. The subjects were four male judokas who were trainees Y. I. University Squad members and the Yoko Ukemi were filmed by two S-VHS 16mm video cameras(60fields/sec.). The selected times were subject to KWON 3D analysis program and kinematical analysis to compare variables of three Yoko Ukemi. Temporal variables(total time-required : TK, TR by each phase), the body part touched order on the mat and COG variables were computed through video analysis while performing right Yoko Ukemi by three stage. From the data analysis and discussion, the following conclusions were drawn : 1. Temporal variables : total time-required(TR) when performing Yoko Ukemi(side breakfall) by each stage, the first stage(full squat posture: FP : 1.11sec.) showed the shortest time, the next was 3rd(Shizenhontai, straight natural posture: NP : 1.41sec.), and 2nd(Jigohontai, straight defensive posture, DP : 1.42sec.), respectively- 2. TR when performing Yoko Ukemi(side breakfall) by each stage, and phase : the first phase(take of phase, average 0.68sec.) showed the longest time, next was the third phase(ukemi phase, 0.39sec.), and the second phase(air phase, 0.23sec.), respectively. 3. When performing yore Ukemi the body part touched order and TR on the mat : hip(0.94sec.) showed the shortest time, the next was elbow hand(0.97sec.), back(0.98sec.), and shoulder(1.04sec.) order. The hip part touched on the mat the first, but slap the mat in order to alleviate the shock try hand palm and forearm before receiving impact (difference 0.03sec,) 4. Vertical COG variables in each event by each stage : e1(ready position, average 78.33cm) moved the highest, the next was e2(jumping position, 70.14cm), e3(transition position, average 64.00cm), e4(landing position, average 35.99cm), and e5(ukemi position, average 18.32cm) order, gradual decrease respectively. And the difference of COG were showed in initial by each stage, because position fo Yoko Ukemi was difference by each stage in preparation position, but in accordance with executing of Ukemi phase that difference of COG was by decreasing, almost equal displacement in e4(landing) and e5(Ukemi)position finally.

• Korean Journal of Materials Research
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• v.1 no.1
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• pp.9-17
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• 1991

TiC coating formed on $Si_3N_4-TiC$ composite ceramic by chemical vapor deposition (CVD) has an improved microstructures, better thermal shock resistance and interfacial bonding than TiN coating does. TiN coating formed by CVD, however, has lower friction coefficients against steels and better chemical stability. The experimental results indicate that the coated insert is superior to the uncoated one in flank and crater wear resistance. And the multilayer coating shows an improved wear resistance than the monolayer coating.

• Journal of Life Science
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• v.16 no.3 s.76
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• pp.454-458
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• 2006

HSF1 is the heat shock transcription factor in Saccharomyces cerevisiae. S. cerevisiae KNU5377 can ferment at high temperature such as $40^{\b{o}}C$. We have been the subjects of intense study because Hsf1p mediates gene expression not only to heat shock, but to a variety of cellular and environmental stress challenges. Basing these facts, we firstly tried to construct the hsf1 gene-deleted mutant. PCR-method for fast production of gene disruption cassette was introduced in a thermotolerant yeast S. cerevisiae KNU5377, which allowed the addition of short flanking homology region as short as 45 bp suffice to mediate homologous recombination to kanMX module. Such a cassette is composed of linking genomic DNA of target gene to the selectable marker kanMX4 that confers geneticin (G418) resistance in yeast. That module is extensively used for PCR-based gene replacement of target gene in the laboratory strains. We describe here the generation of hsf1 gene disruption construction using PCR product of selectable marker with primers that provide homology to the hsf1 gene following separation of haploid strain in wild type yeast S. cerevisiae KNU5377. Yeast deletion overview containing replace cassette module, deletion mutant construction and strain confirmation in this study used Saccharomyces Genome Deletion Project (http:://www-sequence.standard.edu/group/yeast_deletion_project). This mutant by genetic manipulation of wild type yeast KNU5377 strain will provide a good system for analyzing the research of the molecular biology underlying their physiology and metabolic process under fermentation and improvement of their fermentative properties.