• Elastomers and Composites
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• v.39 no.4
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• pp.274-280
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• 2004

Sorage modulus(G'), Impact and rebounding properties of polyurethane(PU), phylon(PH) and injection phylon(IP) foams were studied. The storage modulus of PU foam was dramatically increased with decreasing temperature. But the storage modulus(G') of IP and PH foams were not affected by temperature. The Impact force of PU foams was increased with decreasing temperature. But in the cases of IP and PH foams, the impact forces were not changed with temperature below $20^{\circ}C$. Impact farces of IP and PH foams were increased with the temperature above $20^{\circ}C$, but that of PU foam was not changed. Rebounding resilience of PU foam was lower than those of IP and PH foams from $-20^{\circ}C$ to $40^{\circ}C$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1095-1096
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• 2012

• 프린팅코리아
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• v.9 no.3
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• pp.62-62
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• 2010

마이크로콘트롤스(대표 조병우)에서 공급하고 있는 액화금속코팅 재킷인 J750BL시리즈는 뛰어난 성능과 다양한 기능으로 주목을 받고 있다. 3층으로 구성되어 있는 특수코팅층은 이른바 '연잎 효과(Lotus Effect)'를 구현하고 있다. 연잎 효과는 반발력을 최대화하는 기능을 발휘하는데 있어 중요한 역할을 감당하며 장기간 사용해도 성능 발휘에 지장이 없다. 인쇄작업의 효율성 제고와 친환경성을 감안하고 있다.

• Journal of the Korean GEO-environmental Society
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• v.23 no.10
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• pp.13-19
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• 2022

This paper is to provide the results of usability of the impact force response signal induced from initial and successive rebound impacting a rock specimen for assessing the compressive strength of rock non-destructively. For this study, a device was devised for impacting a rock specimen and a system for measuring the impact force was set up. The impact was carried out by an initial rotating free falling impact and following repetitive impacts from the rebound action which eventually disappears. Three different kinds of rock specimen were tested and an impact force response signal was measured for each test specimen. The total impact force signal energy which is assessed from integrating the impact force response signal induced from initial and rebound impacts was compared with the directly measured compressive strength for each rock specimen. The comparison showed that the total impact force signal energy has a direct relationship with the directly measured compressive strength and the results clearly indicated that the compressive strength of rock can be assessed non-destructively using total impact force signal energy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.666-669
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• 2005

As computer power increased, the system with complex phenomenon has been analyzed with the help of CAE software which can handle the coupled physics, such as electromagnetic, structure, thermal and fluid physics. To predict the electromagnetic repulsion force and the temperature distribution of an air circuit breaker with electric contact mechanism, ANSYS/EMAG, FLOTRAN can be used. Although some assumptions and simplifications were introduced to simulate the model, results from the computational model were in good agreement with actual measurements obtained from experiments.

• Elastomers and Composites
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• v.39 no.3
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• pp.186-192
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• 2004

Compression and rebounding properties of IP(injection phylon), PH(phylon) and PU(polyurethane) foams were studied. The compression stress, rebounding stress, loss compression energy and storage compression energy of foams were decreased with increasing hardness of foams. The compression stress, loss compression energy of IP foams were lower than those of PH and PU. Rebounding stress and storage compression energy of PU foams were higher than those of IP and PH. The compression stress and rebounding of PH foam were lower than those of IP and PU.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.89-89
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• 2011

Cellulose섬유의 염색시 섬유가 물속에 침지되면 섬유표면은 음전하가 형성되어, 용액 속에서 음이온으로 존재하는 염료와의 반발력으로 인해 염료가 섬유에 접근하기가 어려워지며 따라서 염색이 원활하게 이루어지지 않는다. 그러나 염욕에 염화나트륨(sodium chloride, NaCl)이나 망초 즉, 황산나트륨(Glauber's salt, sodium sulfate, Na2SO4)과 같은 전해질을 첨가하면, 양이온인 sodium 이온이 섬유표면과 음이온 염료사이의 반발력을 감소시킨다. 따라서 음이온의 염료는 섬유표면에 접근할 수 있고, 고유한 인력으로 염색이 가능하게 된다. 현재 Cellulose섬유의 상업적인 반응성염료 염색공정뿐만 아니라 최근 연구에서는 전해질 중 대부분 분말망초를 대부분 사용하고 있다. 그러나 분말망초는 별도의 용해과정이 필요할 뿐 아니라, 과량 사용시 용해되지 않은 분말이 섬유 표면에 흡착될 경우 불균염을 초래할 우려 등의 단점이 있다. 이와 같이 작업효율성을 향상시키고 염색을 효율적으로 진행시키기 위해 최근 액상형의 망초가 도입되고 있다. 이 연구에서는 분말 및 액상 망초를 조제로 사용하여 3종류의 Cellulose섬유를 반응성염료로 염색하였다. 담색, 중색, 농색 3가지 염료 농도에 대해 투입하는 망초의 type에 따라 각각의 Cellulose섬유별 균염성 정도에 대하여 비교해 보았다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1160-1165
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• 2004

The purpose of this study was to calculate three dimensional angular displacements, moments and joint reaction forces of the ankle joint during the waist pulling, and to assess the ankle joint reaction forces according to different perturbation modes and different levels of perturbation magnitude. Ankle joint model was assumed 3-D ball and socket joint which is capable of three rotational movements. We used 6 cameras, force plate and waist pulling system. Two different waist pulling systems were adopted for forward sway with three magnitudes each. From motion data and ground reaction forces, we could calculate 3-D angular displacements, moments and joint reaction forces during the recovery of postural balance control. From the experiment using falling mass perturbation, joint moments were larger than those from the experiment using air cylinder pulling system with milder perturbation. However, JRF were similar nevertheless the difference in joint moment. From this finding, we could conjecture that the human body employs different strategies to protect joints by decreasing joint reaction forces, like using the joint movement of flexion or extension or compensating joint reaction force with surrounding soft tissues. Therefore, biomechanical analysis of human ankle joint presented in this study is considered useful for understanding balance control and ankle injury mechanism.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.809-812
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• 1996

Generalized van der Waals equation of state combined with the core-softening theory and temperature dependent repulsive and attractive terms exhibit the anomalous thermal expansion, i.e. density anomaly. Density maxima occur at both positive and negative pressure when the hard-core diameter decreases with increasing temperature, $db_r/dT_r<0$, and at negative pressure when the repulsive force increases with increasing temperature, $da_r/dT_r>0$.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.4
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• pp.55-61
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• 2008

One of the most recent base-isolation systems to improve the earthquake resistance of structures is the Friction Pendulum System(FPS). Simple in design but with versatile properties, the FPS has been used in some of the world s largest seismically isolated buildings, bridges and chemical tanks. FPS using PTFE(Polytetrafl-uoroethylene) based material has been developed to provide a simple and effective way for structures to achieve earthquake resistance. PTFE materials are soft, and are apt to become deformed easily after a few working cycles. In this study, magnetic force is used rather than the usual PTFE materials to improve the material shortcomings. A MF-FPS(Magnetic force-Friction Pendulum System) is proposed, and us shown to effectively protect structures against earthquakes. To demonstrate the advantages of this new system, the MF-FPS is compared with FPS as an attempt to prove its performance. A six-degree-of-freedom model is considered as a numerical example. The ground acceleration data of El Centro, Mexico and Gebze earthquakes are used as seismic excitations. The results showed that MF-FPS improved performance compared with FPS.