• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.182-187
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• 2010

In the various fields of Civil Engineering, shear modulus is very important input parameters to design many constructions and to analyze ground behaviors. In general, a shear wave velocity profile is decided by various experiments before constructing a structure and, analysis and design are carried out by using decided shear wave velocity profile of the site. However, if civil structures are started to construct, the shear wave velocity will be increased more than before constructions because of confining pressure increase by the load of structure. The evaluation of the change in shear wave velocity profile is used very importantly when maintaining, managing, reinforcing and regenerating existing structures. In this study, a non-destructively geotechnical investigation method by using the HWAW method is applied to an evaluation of change in properties of the site according to construction. Generally, the space for experiments is narrow when underground of existing or on-going structures is evaluate, so a prompt non-destructive experiment is required. This prompt non-destructive experiment would be performed by various in-situ seismic methods. However, most of in-situ seismic methods need more space for experiments, so it is difficult to be applied. The HWAW method using the Harmonic wavelet transforms, which is based on time-frequency analysis, determines shear wave velocity profile. It consists of a source as well as short receiver spacing that is 1~3m, and is able to determine a shear wave velocity profile from surface to deep depth by one test on a space. As the HWAW method uses only the signal portion of the maximum local signal/noise ratio to determine a profile, it provides reliability shear modulus profile such as under construction or noisy situation by minimizing effects of noise from diverse vibration on a construction site or urban area. To estimate the applicability of the proposed method, field tests were performed in the change of geotechnical properties according to constructing a minimized modeling bent. Through this study, the change of geotechnical properties of the site was effectively evaluated according to construction of a structure.

• Geomechanics and Engineering
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• 제14권5호
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• pp.407-419
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• 2018

In order to investigate flow characteristics after water inrush from the working face in process of karst tunnel construction, numerical calculation for two class case studies of water inrush is carried out by using the FLUENT software on the background of Qiyueshan tunnel. For each class water inrush from the tunnel face, five cases under different water-inrush velocity are simulated and researched. Three probing lines are selected respectively in the left tunnel, cross passage, right tunnel and in the height direction of the tunnel centerline. The variation characteristics of velocity and pressure on each probing line under the five water-inrush velocities are analyzed. As for the selected four groups probing lines in the tunnels, the change rules of velocity and pressure on each group probing lines under the same water-inrush velocity are discussed. Finally, the water flow characteristics after inrush from the tunnel face are summarized by comparing the case studies. The results indicate that: (1) The velocity and pressure change greatly at the intersection area of the cross passage and the tunnels. (2) The velocity nearby the tunnel side wall is the minimum, while it is the maximum in the middle position. (3) The pressure value of every cross section in the tunnels is basically fixed. (4) As water-inrush velocity increases, the flow velocity and pressure in the tunnels also increase. The former is approximately proportional to their respective water-inrush velocity, while the latter is not. The research results provide a theoretical basis for making scientific and rational escape routes.

• 한국항공우주학회지
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• 제46권5호
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• pp.402-409
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• 2018

이 논문에서는 무인 달착륙 임무를 위해 고려하고 있는 달착륙 시나리오를 제안하고 제안된 시나리오를 기반으로 동력하강단계에서의 최적화 착륙궤적을 구현한다. 동력하강단계에서 달착륙선의 자세 변화는 사용 연료량뿐만 아니라 영상기반 항법의 센서 운용에도 영향을 주므로 자세 변화가 급격하게 이루어지지 않도록 자세각속도를 최적제어 가격함수에 포함하고 이때 자세각속도의 영향을 조절하는 가중치가 최적화 착륙궤적에 미치는 영향을 분석한다. 분석된 결과를 바탕으로 연료 사용을 최소화하고 안정된 자세 변화를 갖도록 최적화 착륙궤적을 설계할 수 있는 적절한 가중치를 제시한다.

• 한국운동역학회지
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• 제17권1호
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• pp.29-39
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• 2007

This study were obtained elapsed time phase-by-phases, displacement, user angle, velocity and angular velocity to analyse kinematically contributing factors at impact of forehand drive motion, on targeting three male players. The results of the study were presented as follows; In the forehand drive swing, the elapsed time by phases was a total of .52 seconds: .30 seconds from backswing to impact and .22 seconds from impact to follow-through, Considering the mean change in locations of COM of each(part$\rightarrow$body segment) at impact, racket head, left shoulder, right wrist and left hip, the left-right directions(X-axis) were showm to be each $.61{\pm}.03$, $1.19{\pm}.08$, $.66{\pm}.03$, $.94{\pm}.06$, and $.45{\pm}.03m$. The displacement differences of COM of each body segment were shown to be -.57, -.05, -.33, and .16m. For the vertical direction(Z-axis), the center of mass was lowest at impact and highest at E3. For the displacement of the right wrist on the left hip, the right wrist moved to .82m to the lower direction without change in the locations of the hip from E1 from E2. When the left hip moved .02m from E2 to E3, the right wrist moved .7m in the upper direction. In respect to the velocity of each body segment, the hip and the shoulder joint accelerated and then the wrist followed. Then the right wrists of all the subjects and their racket heads showed maximum speed, and an effective swing was observed. At the angle of each part, the angle of the right wrist was the smallest at the backswing and the largest at the moment of the impact. Then it increased gradually in the follow-through section. In respect of angular velocity for subject A, the hip moved and the largest change occurred. Immediately before the impact, the subject made a swing using his right wrist, his hip, and the shoulder joint, showing the maximum value, which was judged to be effective.

• Spatial Information Research
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• 제19권1호
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• pp.13-19
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• 2011

도시화가 진행됨에 띠라 고층아파트와 고층빌딩 등 지형지물의 변화가 많이 일어나고 있다. 지형지물의 변화는 강풍 발생의 원인으로 작용하며, 풍속은 풍상측 지형지물의 영향으로 같은 속도의 바람이 붙어올지라도 그 값이 증가 또는 감소한다. 설계기준에서는 이러한 변화를 풍속고도분포계수로 정의하고, 지표면조도에 따라 그 값을 산정하여 반영하도록 하고 있지만 현실에서는 설계자의 주관적 판단에 따라 지표면조도를 결정하야 풍속고도분포계수를 산정하고 있으며, 건설지점의 지표면조도를 구분하기 위한 연구와 자료 또한 부족한 실정이다. 본 논문에서든 최근 고층주거건물이 많이 건설된 지역을 대상으로 건축물의 수직높이에 따분 지표면조도를 GIS프로그램을 이용하여 정량적으로 구분함으로써 풍속 고도분포계수를 보다 합리적으로 산정하고자 한다. 풍하중을 고려한 구조물 설계 시 본 연구에서 제안한 풍속고도분포계수 산정방법을 이용함으로써 설계의 합리성과 구조물의 안전성을 더 높일 수 있을 것이다.

• 한국해안·해양공학회논문집
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• 제31권1호
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• pp.9-16
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• 2019

유속의 크기와 블레이드의 기하학적 형상 변화에 따라 발생하는 조류발전용 쉬라우드 시스템 내 유속 변화를 분석하기 위하여 수리모형실험과 수치해석적 방법을 이용하였다. 모형실험을 통해 시스템의 유입부에서 유속 변화와 블레이드 형상변화에 따른 고유 회전수를 계측하였으며, 수치해석을 통해 쉬라우드내 유속 변화를 분석하였다. 실험 유속이 약 28% 증가하고, 익형의 형상을 적용하였을 때, 쉬라우드 유입부에서 계측된 유속은 최대 약 56% 증가하는 경향을 보였다. 한편, 익형 형상을 적용한 블레이드가 설치된 경우 유입부에서의 유속은 일반 블레이드에 비해 최대 14% 증가하는 경향을 보였으며, 회전수 역시 동일 조건에서 가장 높은 수치를 보였다. 수리실험과 수치해석 결과는 약 13%의 오차를 보였으며, 각각의 결과에서 보이는 유속 변화에 대한 경향은 유사하다. 쉬라우드 내 유속 변화를 수치해석으로 분석한 결과 유입부 대비 블레이드 앞부분에서 유속은 최대 1.7배 증가하는 경향을 보였다. 본 연구를 통해 얻은 시스템 내 유속 변화 분석 결과는 효율적인 조류발전용 쉬라우드 시스템 개발에 필요한 기초 자료를 제시할 수 있을 것으로 판단된다.

• The Journal of Korean Physical Therapy
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• 제27권5호
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• pp.281-286
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• 2015

Purpose: The study was to determine whether mechanical horseback-riding training according to velocity may improve trunk muscles thickness in healthy adults. Methods: Twenty healthy adults participated in this study. The subjects were divided into 2 groups as follows: 10 subjects in high velocity mechanical horseback-riding training (MHRT) and 10 subjects in low velocity MHRT. Subjects in all groups performed a total of 18 sessions 3 times a day for 20 minutes and this experiment lasted for 6 weeks. Mann-Whitney and Wilcoxon Signed Rank test were used in analysis the results of trunk muscle thickness. Ultrasonography was performed to evaluate for thickness of rectus abdominis (RA), external oblique (EO), internal oblique (IO), transverse abdominis (TrA), erector spine (ES), and multifidus (MF) in trunk muscles. Results: Results on the changes of EO, IO, and ES of high velocity MHRT showed a significant increase after 6 weeks (p<0.05). Regarding the changes of EO, IO, ES, TrA, and MF of low velocity MHRT, a significant increase was observed after 6 weeks (p<0.05). The differences in change of trunk muscle thickness before training, after 6-week training between groups, TrA and MF of low velocity MHRT were significantly higher (p<0.05). Conclusion: Based on the results of the current study, the velocity of MHRT was shown to affect change of trunk muscle thickness in healthy adults. In particular, low velocity MHRT may serve as a useful method to provide for TrA, MF thickness improvement related to trunk stabilizers.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.707-711
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• 1998

Ultrasonic test usually was used for defect detection, crack depth measurements and strength estimation of hardened concrete. The essence of the pulse velocity method is that the transition time of an ultrasonic longitudinal pulse is measured in concrete. Ultrasonic velocity was propagated to the age of concrete, made a radical change at that time when concrete was setted. This study which monitored the change in a concrete by ultrasonic test was performed to estimate initial setting and final setting.

• 대한화학회지
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• 제15권1호
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• pp.11-14
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• 1971

A modified form of the integrated Michaelis-Menten equation would provide a useful means of evaluating enzyme kinetic parameters in nonlinear progress reaction with time. A slight modification of the Lineweaver-Burk form (and other variants) using for the velocity, the change in substrate concentration divided by time ($\={v}$), and for the velocity, the change in substrate for the time interval ($\={S}$), allows this linear reciprocal form to be used with negligible error even when as much as half of the substrate is utilized during the time interval.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.237-240
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• 2008

Numerical Analysis for exchanging seawater experiment is carried out in Do-Jang fish port. The change of tidal velocity and water level is derived by the two-dimensional nonlinear shallow-water numerical model. To calculate exchange rate of seawater with the change of tidal velocity and water level, a two-dimensional numerical model is employed which governing equations are Fokker-Plank equations. The calculated exchange rates of each time are described in tables and figures.