• Structural Engineering and Mechanics
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• 제78권4호
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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.

• 대한안전경영과학회지
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• 제21권3호
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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.

• 한국물환경학회지
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• 제26권1호
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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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• 제32권5호
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• pp.290-295
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• 2019

본 연구에서는 액화 천연 가스 운반선 단열 시스템에 적용되는 폴리우레탄 폼(Polyurethane foam, PUF)의 열적 성능 및 내충격성을 향상시키기 위한 목적으로, PUF에 복합 단열 매트를 보강하였다. 복합 단열 매트는 극저온 환경에서 운용이 가능한 케블라, 에어로겔, 그리고 크라이오겔 매트를 선정하였다. 열적 성능은 $20^{\circ}C$의 상온에서 열전도율을 측정하였으며, 내충격성은 $20^{\circ}C$의 상온 및 $-163^{\circ}C$의 극저온에서 30 J의 충격에너지로 낙하 충격 시험을 수행하여 측정하였다. 측정된 열전도율은 유효 열전도율 이론 값을 통해 보강되지 않은 PUF와 비교하였으며, 내충격성은 접촉력, 접촉 시간, 그리고 흡수에너지를 평가하였다. 실험 결과 크라이오겔 복합 매트 보강 시 가장 우수한 열적 성능을 나타났으며, 내충격성은 에어로겔 복합 매트 보강 시 가장 우수하게 나타났다.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2001년도 봄 학술발표논문집 Vol.28 No.1 (B)
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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.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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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.

• 한국군사과학기술학회지
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• 제21권3호
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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.

• 한국운동역학회지
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• 제14권3호
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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.

• 한국재료학회지
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• 제1권1호
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• pp.9-17
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• 1991

화학증착법에 의해 $Si_3N_4-TiC$ 복합재료 위에 코팅된 TiC 박막은 TiN 박막에 비하여 우수한 미세구조와 열충격저항, 계면결합을 가지고 있는 것으로 나타났다. 화학증착법에 의한 TiN 박막은 TiC 박막에 비해 강철과의 마찰계수가 작고 화학적으로 안정하였다. 실험결과는 코팅된 절삭공구가 우수한 내 마모성을 갖고 있는 것으로 나타났다. 또한, 다중 코팅된 절삭공구는 단일 코팅된 공구보다 우수한 내 마모성을 보였다

• 생명과학회지
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• 제16권3호
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• pp.454-458
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• 2006

출아효모인 Sacharomyces cerevisiae S288C균주를 이용한 효모의 게놈이 완성된 후 S. cerevisiae는 다양한 연구 모델로 이용되어져 왔다. 현재까지 효모를 이용한 기능 유전체학 측면에서의 연구는 laboratory strainin인 S288C 균주 또는 그 유래의 균주들이다. 그러나 자연에서 분리된 효모 또는 산업적으로 이용되어지고 있는 S. cerevisiae의 유전학 측면에서의 연구는 낮은 포자형성률 및 형질전환률, 그리고 S288C 균주와의 게놈상의 상이성 때문에 거의 이루어지지 않고 있다. 여기서 우리 연구진은 자연에서 분리된 Saccharomyces cerevisiae KNU5377 균주를 이용하여 random spore analysis를 통해 MATa 및 $MAT{\alpha}$ 타입의 각각의 haploid cell을 분리 후 이미 보고된 KanMX module를 가지고 round PCR기법에 의한 short flanking homology 기법을 이용하여 전사조절인자인 HSF1 유전자가 치환된 변이주를 구축할 수 있었다. 덧붙여, 모든 유전자에 이 기법을 적용할 수는 없다는 것을 확인하였다. 앞으로 이 변이주를 통해 기능 유전체학적인 측면에서 이 유전자의 스트레스와의 관련성을 연구하고자 한다.