• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.50-52
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• 1998

1. 서론 : 오래전부터 기체를 액상에 분산시킴으로써 물질 전달 속도를 증가시킴과 동시에 기-액간의 접촉면적을 넓히려는 연구 즉, 기-액간의 접촉 경계면을 통하여 이루어지는 기체흡수에 관한 연구가 다각적으로 이루어져 왔다. 그러나, 기존의 흡수장치에서는 기-액간의 접촉면적을 정확히 계산할 수 없고, 기체에 의한 액체의 범람이나 편류현상등이 발생하여 액체나 기체의 유속에 제한을 주는 등 기술적인 문제점을 가지고 있다. 따라서 이러한 기존 흡수공정들의 문제점을 극복하기 위하여 최근에 제안된 것이 막을 이용하여 기체와 흡수제인 액체의 접촉을 인위적으로 제어할 수 있는 중공사막 접촉기이다. 본 연구에서는 수용성 흡수제가 흡수모듈과 탈착모듈을 순환하는 순환식 중공사막 접촉기를 이용하여 혼합기체(N$_2$/CO$_2$ = 80/20)로부터 이산화탄소를 선택적으로 분리.회수하고자 하였으며, 또한 흡수제의 농도, 유속변화, 그리고 진공식 탈착모듈에서 압력변화에 따른 기체투과 특성을 고찰함으로써 운전조건의 최적화와 그 응용 가능성을 제시하고자 하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1147-1156
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• 2011

A contact-type area-varying capacitive displacement sensor, or CLECDiS, can measure displacements over millimeter ranges with nanometer resolution. However, a small changes in the contact condition due to the surface profile or friction, which are inherent characteristics of contact-type sensors, lead to significant distortion of the output signal. Therefore, ensuring reliable contact conditions during CLECDiS measurements is the most important area to be improved in their actual use. Herein, in order to design an instrument for ensuring reliable contact conditions, the contact condition is analyzed by characterizing the signal distortion, observing the pressure distribution between the contacting surfaces, and measuring the motional errors of the sensor using a laser Doppler vibrometer (LDV). The manufactured instrument enables a CLECDiS to be used in an ultraprecise positioning system with improved reliability.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.278-279
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• 2003

광도의 기본 단위인 칸델라(Candela) 눈금은 물론 복사조도(irradiance), 조명도(illuminance)와 같은 유도 단위를 실현하기 위해서는 검출기의 시야를 한정하는 개구면적의 정밀한 측정이 필요하다. 여기에서는 가장자리의 광학적 검출방법에 의한 개구면적의 산출방식을 소개하고, 가우시안광에 의한 면적 측정법의 측정값과도 비교하여 그 결과를 보여준다. 기존의 개구 면적 측정방식으로 한가지 방법은 탐촉자를 물리적으로 접촉시켜서 개구의 가장자리를 결정하고, 개구의 기하학적 모양을 원으로 가정하여 면적을 산출하는 방식이 있는데, 이 방법을 사용하면 기계적인 접촉에 의하여 칼날과 같았던 개구의 가장자리가 손상을 입게 되기 때문에 측정이 잘못되는 것은 물론이고, 이렇게 측정된 개구를 사용하게되면 손상된 부위에 의한 면적의 변화와 이로 인한 산란이 증가하게 된다. (중략)

• Journal of Korean Society of Steel Construction
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• v.12 no.2 s.45
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• pp.143-150
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• 2000

Depending upon the combination of tolerances specified in the standards on bolt, nut and washer for high tension bolt sets, there arises center-to-center deviation between bolt and washer. This deviation nay cause loss of effective contact area between nut- and washer-faces, which leads to some dispersion of the torque coefficient K. By adapting circular arc surface instead of flat surface for the nut, it is shown through numerical analyses that the dispersion of the torque coefficient can be minimized. In this way, optimum radius of curvature of the nut bearing surface is proposed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.193-199
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• 1999

In the 3-Dimensional contact of the smooth spheres, the effects of friction on the contact area and the distribution of contact pressure was studied numerically. The contact area and pressure distribution was evaluated for the only normal load and for the case of a normal load in the presence of a tangential traction. To do this work, the technique of simple discretization using the load . displacement relationship for a uniformly distributed load of a rectangular patch was used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.98-106
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• 2016

Measurements of the elastic modulus and hardness using a nano indentation machine rely on the equation for the fitted contact area, which is valid for only sink-in materials. For most soft engineering materials that involve pile-up behavior rather than sink-in, the contact area equation underestimates the contact area and thus overestimates the elastic modulus and hardness. This study proposes a correction method to amend erroneous hardness measurements in pile-up situations. The method is a supplemental derivation to the original hardness measurement with the known value of the elastic modulus. The method was examined for soft engineering metals, Al 6061 T6 and C 12200, via tensile tests, nano indentation tests, impression observations, and finite element analysis. The proposed technique shows reasonable agreement with the analytical results accounting for strain gradient plasticity from a previous study.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.77-79
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• 2008

본 논문에서는 고리모양 판의 멀티모드를 이용하여 동작하는 선형 초음파모터에 대한 해석방범을 제시하였다. 고정자의 변위는 3D 유한요소법을 이용하여 해석하였으며, 시간에 따른 접촉 면적과 접촉표면의 운동속도의 변화를 반영한 해석적 방법을 이용하여 고정자와 이동자 사이의 접촉을 해석하였다. 해석방법 검증을 위하여 외경 10.00mm, 두께 1.00mm인 선형 초음파모터 모델에 대한 해석결과를 실험결과와 비교하였다.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.39-42
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• 1998

1. 서론 : 막을 경계로 접촉한 두 상(phase)간의 물질전달에 의해 물질을 효과적으로 분리해내는 막접촉기(membrane contactor) 방식은 추출이나 흡수에 적용되고 있다. 이것은 고전적인 충전탑이 갖는 접촉면적의 한계, 불안정한 유체유동의 단점을 가급적 극복할 수 있다는 측면에 있다. 막접촉방식의 하나인 막 흡수법의 경우, 흡수제(absorbent)를 정지시킨 contained(혹은, supported) liquid membrane 방식에서 인공폐의 원리를 기초로 독립적으로 분리시킨 흡수와 탈착모듈간의 계속 순환시키는 circulatory membrane absorber방식이 제안되었다.(생략)

• The korean journal of orthodontics
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• v.40 no.5
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• pp.304-313
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• 2010

Objective: The aim of this study was to evaluate the occlusal force and contact area and to find its associating factors in Koreans. Methods: Occlusal force and contact area in maximum intercuspation were measured using the Dental $Prescale^{(R)}$ system in 651 subjects (15 with normal occlusion, 636 with various malocclusions divided into subgroups according to the skeletal pattern, Angle's molar relationship, age and gender). Results: Occlusal force of the normal occlusion group ($744.5{\pm}262.6N$) was significantly higher than those of the malocclusion group ($439.0{\pm}229.9N$, $p$ < 0.05). Occlusal force was similar regardless of differences in ANB angle or Angle's molar classification, however the increase in vertical dimension significantly reduced occlusal force ($p$ < 0.05). Conclusions: Occlusal force was significantly lower in the malocclusion group compared to the normal occlusion group, and in females compared to males, but it was not affected by age, antero-posterior skeletal pattern or molar classification. Although a hyperdivergent facial pattern indicated lower occlusal force compared to a hypodivergent facial pattern, the differences in skeletal pattern were not the primary cause of its decrease, but a secondary result induced by the differences in occlusal contact area according to the facial pattern.

• Tribology and Lubricants
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• v.29 no.2
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• pp.85-90
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• 2013

The effects of contact pressure on the sliding wear behavior of mild steel in a pin-on-disc type apparatus were investigated. Sliding wear tests were conducted with various combinations of the load and apparent area of contact. The wear behavior of mild steel as a function of sliding speed was independent of contact pressure. However, the wear rate at different sliding speeds was influenced by the load regardless of the apparent area of contact. This was attributed to the fact that there may be no difference in the real area of contact for any combination of the load and apparent area of contact.