• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.29-32
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• 2012

변장비의 변화가 사각실린더에 작용하는 유체력에 미치는 영향을 알기 위해 EDISON_열유체를 사용하여 수치해석을 하였다. 낮은 레이놀즈수 영역($100{\leq}Re{\leq}200$)에서 사각실린더의 변장비(W/H)를 0.5, 0.75, 1, 2로 변화시키며 해석을 수행하였고, 레이놀즈수와 변장비에 따른 스트로할수(St), 항력계수($C_D$), 양력계수($C_L$)를 비교하였다. 본 논문에서는 레이놀즈수와 실린더의 변장비가 스트로할수, 항력계수, 양력계수에 미치는 영향을 알아보는 데 중점을 두었다. 해석결과 레이놀즈수가 증가하고 변장비가 감소할수록 스트로할수, 항력계수, 양력계수가 증가하는 것을 확인하였다. 본 논문을 통해서 레이놀즈수와 사각실린더의 변장비가 사각실린더에 작용하는 유체력에 영향을 미친다는 것을 알 수 있었다.

• Journal of the Korean Geotechnical Society
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• v.20 no.8
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• pp.123-133
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• 2004

The magnitudes of wall thrust acting on quay walls can easily vary due to the development of excess pore pressure in backfill. In this research, a new displacement model was proposed to predict the displacement of the wall considering such magnitude variations of the wall thrust. This model is based on Newmark sliding block concept. The magnitude variation of the wall thrust is modelled by varying the magnitude of yield acceleration. The parametric study was performed to analyze the effects of input parameters on the seismic displacement of the wall, and the validity of this model was verified by comparing its predicted displacements with those of Is shaking table tests.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.408-412
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• 2007

본 연구는 자갈하상하천에서 하상에 분포하는 입자에 작용하는 전단력을 이용하여 등가조도를 산정할 수 있는 모형을 개발하였다. 등가조도는 기존의 연구들처럼 경험적으로 특정입도에 의해 산정하지 않고 하상에 분포하는 각 입자에 작용하는 입자 전단력을 산정하고, 하상 평균전단력과의 관계로서 산정하였다. 입자 전단력은 항력을 통해 산정하였으며, 이때 항력계수는 입자의 돌출 높이를 고려할 수 있도록 하였다. 또한 입자에 부딪히는 평균유속은 수치적분을 통해 입자의 돌출 높이에 따라 가변성을 고려할 수 있도록 식으로 제시하였다. 단위면적당 입자 전단력과 하상 평균 전단력과의 관계를 통해 등가조도의 함수로서 식을 제시한 후 수치해석방법의 하나인 증분 탐색법을 통해 등가조도를 산정할 수 있도록 하였다. 그리고 산정된 등가조도를 이용하여 수위-유량관계 및 흐름저항매개변수를 산정하여 적정성을 검토하였다.

• Korean Journal of Childcare and Education
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• v.6 no.1
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• pp.67-93
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• 2010

The purpose of the present study was to examine how 25~36-month-old toddlers' temperament, mother's rearing attitude, teacher interaction relates to their language abilities and to analyze the predictive power of these variables in predicting language ability. The subjects were 206 toddlers, 206 mothers and 38 class teachers at child care center in G metropolitan city. The collected data were analyzed using Pearson's correlation analysis and stepwise multiple regression analysis on SPSS program. The results of this study were as follow. First, there was a significant relationship between mother's rearing attitude, teacher interaction and toddlers language abilities. However, toddlers' temperament showed no significant correlations with toddlers language abilities. Second, teacher's positive attitude was the best predictor of toddlers language abilities. Toddlers' reactivity and mother's rational guidance were also predictors of toddlers' language abilities.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.6
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• pp.573-584
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• 2014

In this study, the variations of cutter acting forces depending on cutting conditions were examined to obtain basic data for roadheader cutting head design. The linear cutting tests were performed in the condition of different attack angles, penetration depths, cutter spacings by using a slim conical pick for the light cutting condition. Cutter acting forces were measured by 3-directional load cell under different test conditions, and the analysis for cutting performance were carried out after calculating average values of the measured results. It is confirmed that the optimal cutting condition for the mortar specimen is the 50 degree attack angle, the cutter spacing of 12 mm, the cutting depth of 9 mm which are obtained from the analysis results. In addition, 50 degree attack angle is more effective than 45 degree attack angle to design optimal specifications of cutting head.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1995.10a
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• pp.117-119
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• 1995

입사파의 파장에 비교하여 그 대표 길이가 작은 소형 구조물에 작용하는 파력을 산정하는 경우에는 통상적으로 Morison식이 이용되고 있다. 원주나 판 등의 단순한 구조물에 관한 Morison식 중 유체력 계수(관성력 및 항력계수)에 관해서는 이미 많은 연구가 나와 있어 이들에 작용하는 파력을 고정도로 추정하는 것이 가능하다. 한편 이들 중에는 어초의 경우에서와 같이, 단순한 부재가 여러개로 조합되어 복잡한 구조물을 형성하고 있는 경우를 많이 볼 수 있다. (중략)

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.234-240
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• 2017

In this study, the influences of rail surface roughness on dynamic wheel-rail forces currently employed in conventional lines were assessed by performing field measurements according to grinding of rail surface roughness. The influence of the grinding effect was evaluated using a previous empirical prediction model for dynamic wheel-rail forces; model includes first-order derivatives of QI (Quality Index) and vehicle velocity. The theoretical dynamic wheel-rail force determined using the previous prediction equation was analyzed using the QI, which decreased due to rail grinding as determined through field measurements. At a constant track support stiffness, an increase in the QI caused an increase in dynamic wheel-rail forces. Further, it can be inferred that the results of dynamic wheel-rail analysis obtained using the measured data, such as the variation of QI due to rail grinding, can be used to predict the peak dynamic forces. Therefore, it is obvious that the optimum amount of rail grinding can be determined by considering the QI, that was regarding an operation characteristics of the target track (vehicle velocity and wheel load).

• Journal of Navigation and Port Research
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• v.43 no.1
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• pp.9-15
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• 2019

Mooring bollards are the mandatory facility in ports for they are the objects used to fasten the ship to its position at the berth. All the mooring bollards were installed following suggested sizes, numbers, materials and shape of installation according to Port and Fishing Design Standards. However, Korea has no management standard for use of mooring bollards to safety in ship berthing. In this research, the installation standard for mooring bollards including the holding power applied to mooring bollards in berthing was studied. Also, the performance of mooring bollards for minimum safety guarantee in berthing based on research of various specification by their sizes was analyzed. The analysis on mooring bollards was examined by each power on mooring bollards from the applied force in berthing divided into horizontal and vertical direction in order to examine the performance of domestic mooring bollards, the limit force is calculated based on detailed specification research result. As a result, the working stress according to the towing force was found to be at least 150Mpa and it was evaluated to be 60% of the limit strength. Also, by comparing each forces, the appropriateness was examined and the specification of maximum capability calculated. This performance evaluation method based on detail specification of mooring bollards will be expected to be useful to examine the appropriateness of mooring bollards for various types of vessel in berthing and to develop maintenance and management standard through the performance change evaluation referring to mooring bollard detailed specification changes.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.5
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• pp.33-41
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• 1988

내연기관에서 crankshaft는 piston에 작용하는 수직 gas force 및 관성력을 회전력으로 바꾸어 주는 역할을 한다. 그러므로 engine작동중 높은 부하를 반복적으로 받기 때문에 이에 견딜 충분한 stiffness를 유지해야 한다. Engine의 stroke 운동시에 gas force와 관성력이 변하고 crankshaft의 형상이 복잡하므로 실제적으로 응력계산은 간단하지 않다. 여기에서는 crankshaft에 작용하는 하중과 반력을 계산하고 crankshaft의 stress 및 safety factor를 계산하여 crankshaft를 설계하는 방법을 설명하고자 한다. 근래 FEM에 의한 stress analysis를 많이 수행하나, loading condition을 주기 위해서는 classical method에 의해서 구할 수 있다.

• Journal of the Korean Geotechnical Society
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• v.16 no.5
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• pp.141-148
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• 2000

사면 안정 해석은 주로 파괴 활동면의 전단 강도와 발휘되는 전단 강도의 최대비로서 표현되는 파괴활동의 추정을 위해 기존의 고전적인 방법을 사용하거나 이와 유사한 방법등이 사용되어 왔다. 이러한 방법들은 토질에 있어서의 상호 작용력과 그에 따른 전당력 및 사면 활동면의 반복되는 추정등의 가정으로 불확실성을 내포하고 있다. 본 연구에서는 토질전체를 연속체로 규정하고 비선형 유한요소법을 이용한 토질의 실제 응력과 강도를 정확하게 계산하였다. 사면 안정은 점차적 인증력의 증가로서 사면의 붕괴 활동면이 나타나FEo 까지로 해석되었다. 제시된 방법의 세부적인 사항은 예제를 통하여 설명되어 있다.