• 대한기계학회논문집
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• 제13권5호
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• pp.847-854
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• 1989

본 연구에서는 V-벨트 CVT의 핵심인 변속비-부하토오크-축력에 대한 이론적 연구에 이어 실험적 연구를 통하여 전 연구에서 구한 이론식과 비교 검토하고 V-벨트 CVT의 기초 설계자료를 얻고자한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.69-72
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• 2005

In this study, effects of IHPs with various resting times to cell adhesion were investigated through the measurements of cell adhesive force, number and area of focal contacts (stained vinculin spots), and projected cell area, perimeter and circularity. In addition correlation tests and curve estimations using the experimental results were performed fur the finding an essential factor for increment of cell adhesive force. Tn the results, immediately after mechanical stimuli (150 minutes after seeding) and one hour later (210 minutes after seeding), the average adhesive force of experimental group 5 (resting time: 15min) compared with that of control group at same culture time was increased significantly (p<0.05). Average projected area and perimeter of cells at Group 5 were increased significantly (p<0.05), while average circularity of cells at Group 5 incubated fur 210 minutes was decreased significantly (p<0.05). In the digital image analysis of focal contacts containing vinculins, area and numbers of focal contacts per cell at Group 5 were higher than those of the other groups. This study indicated that IHP with appropriate resting time could contribute in improving cell adhesive force, cell spreading, development of cytoskeleton and formation of focal contacts. And cell adhesive force was correlated to the morphological aspects of cell and development of focal contacts. Particularly, area of focal contacts was closely related to cell adhesive force.

• 한국군사과학기술학회지
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• 제20권5호
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• pp.647-653
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• 2017

In this paper, we deal with the experimental verification of 1D virtual force field algorithm based reflexive local path planning on uneven and dusty environment. The existing obstacle detection method on uneven and dusty environment and 1D virtual force field based reflexive local path planning algorithm simply are introduced. Although the 1D virtual force field algorithm is verified by various simulations, additional efforts are needed to verify this algorithm in the real-world. The introduced methods are combined with each other, installed to real mobile platforms and verified by various real experiments.

• 한국멀티미디어학회논문지
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• 제12권1호
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• pp.147-155
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• 2009

교합력 측정과 분석은 힘의 관계를 분석하여 치아의 역학적 관계를 진단하는 방법이다. 본 연구에서는 새로운 교합력 측정 및 분석 시스템 개발의 기초 연구로써 측정 소프트웨어를 설계 및 구현하고 유용성을 평가한다. 이를 위해 교합력의 정상, 비정상을 효과적으로 측정할 수 있는 다양한 도구들을 개발하였다. 첫째, 치아에 작용하는 힘의 중심 변화를 나타내는 표지의 경로와 14개로 나뉜 치아 영역별 교합력 분포를 정량적인 수치와 함께 가시화 하였으며, 둘째, 교합력이 어느 치아의 특정한 영역으로 치우쳐서 작용하는가를 판단할 수 있도록 하기 위해 좌 우 치아 영역의 힘의 균형을 비율로 측정할 수 있는 도구를 구현하였다. 또한 0.5초 단위로 측정된 교합력의 변화를 소프트웨어 상에서 기록할 수 있도록 하였다. 센서 시트 방식의 측정 하드웨어와 연동하여 테스트한 결과, 힘의 분포와 균형을 효과적으로 확인할 수 있었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권4호
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• pp.569-579
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• 2013

A steel-type breakwater that uses a submerged dual horizontal porous plate was originally proposed by Kweon et al. (2005), and its hydrodynamic characteristics and design methodology were investigated in a series of subsequent researches. In particular, Kweon et al. (2011) proposed a method of estimating the vertical uplift force that acts on the horizontal plate, applicable to the design of the pile uplift drag force. However, the difference between the method proposed by Kweon et al. (2011), and the wave force measured at a different time without a phase difference, have not yet been clearly analyzed. In this study, such difference according to the method of estimating the wave force was analyzed, by measuring the wave pressure acting on a breakwater model. The hydraulic model test was conducted in a two-dimensional wave flume of 60.0 m length, 1.5 m height and 1.0 m width. The steepness range of the selected waves is 0.01~0.03, with regular and random signals. 20 pressure gauges were used for the measurement. The analysis results showed that the wave force estimate in the method of Kweon et al. (2011) was smaller than the wave force calculated from the maximum pressure at individual points, under a random wave action. Meanwhile, the method of Goda (1974) that was applied to the horizontal plate produced a smaller wave force, than the method of Kweon et al. (2011). The method of Kweon (2011) was already verified in the real sea test of Kweon et al. (2012), where the safety factor of the pile uplift force was found to be greater than 2.0. Based on these results, it was concluded that the method of estimating the wave force by Kweon et al. (2011) can be satisfactorily used for estimating the uplift force of a pile.

• 생물환경조절학회지
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• 제1권1호
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• pp.28-36
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• 1992

The wind pressure distributions were analyzed to provide fundamental criteria for the structural design on e single-span arched house according to the wind directions through the wind tunnel experiment. In order to investigate the wind force distributions, the variation of the wind force coefficients, the mean wind force coefficients, the drag force coefficients and the lift force coefficients were estimated by using the experimental data. The results obtained are as follows: 1. When the wind direction was normal to the wall, the maximum positive wind pressure along the height of the wall occurred approximately at two-thirds of the wall height because of the effects of boundary layer flow. 2. When the wind direction was 30$^{\circ}$ to the wall, the maximum positive wind force occurred at the windward edge of the wall. When the wind direction was parallel to the wall, the maximum negative wind force occurred at the windward edge of the wall. 3. The maximum negative wind force along the width of the roof appeared around the width ratio, 0.4, and that along the length of the roof appeared around the length ratio, 0.5. 4. According to the results of the mean wind force coefficients analysis, the maximum negative wind force occurred on the roof at the wind direction of 30$^{\circ}$. 5. The wind forces at the wind direction of 30$^{\circ}$ instead of 0$^{\circ}$ are recommended in the structural design of supports for a house. 6. To prevent partial damage of a house structure by wind forces, the local wind forces should be considered to the structural design of a house.

• 한국정밀공학회지
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• 제11권2호
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• pp.141-148
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• 1994

국가간에 힘 측정 또는 힘 측정기기의 교정 결과에 대한 상호 신뢰를 확보하기 위해서는 힘 표준에 대한 상호비교가 필수적이다. 본 논문에서는 한국의 힘 표준에 대한 국제적 신뢰를 확보하기 위하여 세계 여러 나라들과 힘 표준에 대한 국제비교 연구를 수행한 독일연방물리청과 힘 표준의 상호비교를 실시하였다. 비교시험 결과 한국과 독일의 힘 표준의 상대 편차는 100 kN .approx. 500 kN벙위에서 .+-. 5.5*$10^{-5}$ 이내로 나타났으며, 한국의 힘 표준의 정확도가 국제적 수준임을 확인하였다.

• 한국유체기계학회 논문집
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• 제14권5호
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• pp.48-54
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• 2011

Structural modifications of a ship may cause a fatal accident such as sinking and wrecking of ship. Especially, barge ship can be easily reconstructed to load more bulk cargo. In this study, for a real accident case, change of mooring force due to structural modification was analyzed to evaluate accident risk. A two dimensional dynamic model for the barge ship was constructed to compute mooring forces with related to floating motion. The equation of motion was established in Matlab code and buoyancy was calculated by using direct integration of submerged volume. The results showed that wind force, current force, and mooring force after rebuilding was approximately 4.3 kN, 14 kN, 1,561 kN respectively. The maximum force of mooring force according to the length of mooring cable were 1,614 kN at 30 m of mooring cable. Thus, an arbitrary modification of ship lead instability and unreliable result so that illegal rebuilding of ship should be avoided.

• 한국정밀공학회지
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• 제15권2호
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• pp.146-153
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• 1998

NC machines with 4 or 5 axes are capable of various tool approach motions, which makes interference-free and high machinablity machining possible. This paper deals with how to integrate these two advantages (interference-free and high machinability machining) in multi-axes NC machining with a ball-end mill. Feasible tool approach region at a point on a surface is first computed, then among which an approach direction is determined so as to minimize the cutting force required. Tool and spindle volumes are considered in computing the feasible tool approach region, and the computing time is improved by trans-forming surface patches into minimal enclosing spheres. A cutting force prediction model is used for estimating the cutting force. The algorithm is developed so as to be applied to 4- or 5-axes NC machining in common.

• 대한치과교정학회지
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• 제37권6호
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• pp.432-439
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• 2007

초탄성 니켈-티타늄 호선의 하중값은 온도 변화에 따라 변화함이 보고된 바 있다. 따라서 본 연구에서는 온도가 변화함에 따라 니켈-티타늄 합금 호선의 하중값이 어떻게 변화하는지 알아보고자 하였다. $37^{\circ}C$ 항온 상태에서 $0.016"{\times}0.22"$ 니켈-티타늄 호선을 3.1 mm까지 변위시키는 3점 굴곡 실험을 시행하여 하중 시와 탈하중 시의 1.5mm 변위지점의 하중값을 측정하고 이 지점에서 구강내 온도 변화를 고려한 온도 변화 실험을 시행하였다. $20^{\circ}C$ 저온수 또는 $50^{\circ}C$ 고온수를 호선에 흘려보냄으로써 온도 변화를 주었다. 저온 실험은 저온수로 온도 변화를 주고 $37^{\circ}C$ 항온 온도로 회복된 후에 다시 저온수를 흐르게 하는 방법으로 10회 시행하였고 고온 실험도 동일한 방법으로 시행하였다. 그 결과 하중 시 1.5mm 변위지점의 하중값은 저온 실험 및 고온 실험 후 $37^{\circ}C$로 회복된 후에도 모두 감소된 값을 유지하였다. 반대로 실제로 치아에 가해지는 교정력으로 생각되는 탈하중 시 1.5 mm 변위 지점의 하중값은 저온 실험 및 고온 실험 후 온도가 $37^{\circ}C$로 회복되어도 모두 증가된 값을 유지하였다. 이상의 결과를 종합해 볼 때 온도변화를 거친 후 초탄성 니켈-티타늄 합금 호선의 하중 시 힘은 감소하였고 탈하중 시 힘은 증가되므로, 임상에서 니켈-티타늄 호선을 적용 시에는 $37^{\circ}C$에서의 하중-변위 곡선에서 나타나는 힘에 비해 더 작은 하중 시 힘과 더 큰 탈하중 시 힘이 적용될 수 있음에 유의하여야 한다.