• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.05a
• /
• pp.924-927
• /
• 2007

In this study, adaptation of two-way shape memory effect of SMA wire to the actuator is examined. Therefore the SMA characteristics which are training, material properties, response time at different thermal cycling rates are tested. During training, permanent deformation is accumulated till a certain number of cycle and then saturated. The amount of two-way strain is unchangeable over all cycle and the slope of strain(or stress)-temperature curve is slower as the increase of applied stress. The rate effect is observed resulted from the thermal distribution which heating profile differs from cooling as thermal cycling time. Using the estimated SMA properties, an experimental test for the simple smart wing is performed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.1043-1046
• /
• 2001

In this study, characteristics of LPB having gold anode fabricated by sputtering methode were analyzed. As results, The 1st efficiency and the impedance characteristics of LPB decreased with increased gold coated on anode and current collector. But the rate characteristics and charge-discharge cycling characteristics increased with increased gold coated on anode and current collector. During 2C discharge of the rate characteristics test, the rate characteristics of LPB without gold coated and the rate characteristics of LPB with gold coated in twice were 159mAh/g and 189mAh/g, respectively. The discharge capacity was gradually degreased with the discharge cycling to about 20th cycles. But LPB with gold coated in twice was stabilized than LPB without gold coated.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.10a
• /
• pp.115-118
• /
• 2003

This research aims to measure mechanical tensile properties of CFRP composites for cryogenic tank material. Through the cryogenic chamber, tensile tests are peformed under cryogenic temperature for graphite/epoxy fabric specimen aged at $-150^{\circ}C$ for 30hrs with load and graphite/epoxy unidirectional specimen 3-cycled from RT to $-100^{\circ}C$ with load. For graphite/epoxy fabric specimen, tensile modulus showed to increase after aging at cryogenic temperature(CT) while to decrease after aging at room temperature(RT) and tensile strength is more decreased after CT-aged than at RT-aged. For graphite/epoxy unidirectional specimen, tensile modulus was almost not changed after 3-cycling but strength showed the trend of decrease as increase the number of cycling.

• The Journal of the Korean dental association
• /
• v.23 no.12 s.199
• /
• pp.1031-1037
• /
• 1985

The purpose of this study was to evaluate the marginal sealing ability of 'vivadent.' Using freshly extracted human teeth and 2% aqueous methylene blue, the marginal leakage of dye in restorative materials such as vivadent with acid etching technique, Durafill with acid etching technique, silar with acid etching technique, Adaptic, and Amalgam were investigated at 37℃ and under temperature cycling in range of 4℃-60℃. The results were as follows; 1. All filling materials showed some degree of marginal penetration by 2% methylene blue dye. 2. Vivadent with acid etching technique revealed effective marginal sealing ability, but under temperature cycling it showed increased marginal leakage. 3. All resins showed greater marginal leakage than amalgam restoration. 4. Vivadent had the most effective marginal sealing ability in experimented resins.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.334-334
• /
• 2011

We applied N-ion bombardment and heat treatment to the Cu thin films deposited on aluminum oxide layer for the enhancement of adhesion. With e-beam evaporation method. $1,000{\AA}$ thick Cu pre-bombardment layer was deposited on the aluminum oxide surface and then N-ion beam was bombared in order to mix the atoms at the film/substrate interface. Additional $4,000{\AA}$-thick Cu film was the coated. Subsequently, the ion mixide Cu on aluminum oxide was annealed at $200^{\circ}C$ and $300^{\circ}C$ in vacuum.

• Restorative Dentistry and Endodontics
• /
• v.8 no.1
• /
• pp.167-172
• /
• 1982

The purpose of this study was to evaluate the marginal sealing ability of "Silar". Using freshly extracted human teeth and 2% acquous methylene blue, the marginal leakage of dye in restorative materials such as Silar, Silar with acid etching technique, Hi-Pol, Hi-Pol Enamel Bond system, Adaptic and Amalgam were investigated at $37^{\circ}C$ and under temperature cycling in range of $4^{\circ}C-60^{\circ}C$. The results as follows; 1. All filling materials showed some degree of marginal penetration by 2% methylene blue dye. 2. Silar with acid etching technique revealed effective marginal sealing ability, but under temperature cycling it showed increased marginal leakage. 3. All composite resins showed greater marginal leakage than amalgam restoration. 4. Silar had the most effective marginal sealing ability in experimented composite resins.

• Progress in Superconductivity and Cryogenics
• /
• v.22 no.4
• /
• pp.24-30
• /
• 2020

The test results of the ITER toroidal field conductors demonstrated a decrease of the current sharing temperature (Tcs) with an increase in the number of electromagnetic cycles in general. This is associating with several factors. One of them is the superconducting Nb3Sn filaments cracking and another one is the redistribution of the relative deformation of the Nb3Sn strands under Lorentz forces. Despite these factors, some conductors have shown the absence or significantly less degradation of Tcs during electromagnetic cycling. This article considers another possible reason for a more stable conductors Tcs behavior, namely, the local compression of Nb3Sn wires in the cross section of a conductor. In this article presents the results of a quantitative analysis Nb3Sn superconducting filaments cracking of strands extracted from a conductor that has passed electromagnetic cycling and the model of a conductor compaction, as well as calculation results based on this model are presented also.

• Journal of Korean Society of Steel Construction
• /
• v.22 no.3
• /
• pp.261-269
• /
• 2010

It is now possible to design buildings in various forms using a diagrid structural system, which is the one of the most useful structural systems. It is difficult to design and construct the connections, however, and the bucklings in braces weaken the seismic performance of structures. In this study, the initial stiffness, ductility, and energy-dissipated capacity of a diagrid and a diagrid BRB were evaluated via frame tests. The results of the cycling load tests showed that the diagrid BRB had better initial stiffness and ductility, and dissipated extra energy after the BRBs were yielded.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.98.2-98.2
• /
• 2011

지구 온난화의 원인이 되는 이산화탄소를 저감하며 유해한 배기가스를 배출하지 않는 수소연료전지자동차(FCV)에 대한 관심이 높아지고 있다. 한국가스안전공사에서 현재 구축하고 있는 평가장비는 이러한 수소연료전지자동차용으로 사용되는 고압용기의 수압반복시험 및 밸브류로 구성된 고압수소저장시스템의 단품 및 시스템 평가를 통한 안전신뢰성 검증을 목적으로 하고 있다. 현재 수소연료전지자동차는 차량이나 부품의 시험 방법에 대한 통일된 기준/표준/시험법이 아직 완전하게 정비되어 있지 않고, 시장에서의 도입 제도, 기준 등이 만들어지고 있는 현실이다. 또한 연료로 수소를 사용하는 도입단계에 있기 때문에, 수소용기가 반복압력변동에 따라 어떤 거동을 나타내는지에 대한 실험관련 연구가 미진한 상태이다. 따라서 수소연료전지자동차용 고압수소저장시스템에 대한 내구성, 안전성 확보를 위하여 수소연료전지자동차에서 중요한 부품인 용기에 대한 반복피로시험이 필요하다. 특히 복합재 용기 분야에서 Type3용기에 대한 높은 안전성과 내구성이 보고되고 있지만 실질적으로 얼마나 다른 용기에 비해 높은 성능을 가지고 있는지 국내에서는 체계적으로 검증된바 없다. 따라서 구축된 수압반복 장비를 이용하여 Type3 용기에 대한 수압반복시험을 실시하였으며, 이를 통해 수소용기의 거동을 확인하고자 한다.

• Journal of the Microelectronics and Packaging Society
• /
• v.12 no.1 s.34
• /
• pp.65-71
• /
• 2005

At present, Electronic industries push ahead to eliminate the Pb(Lead) -a hazardous material-from all products. Especially, we have performed to select the optimum standard composition of lead free alloy for the application to products for about 3 years from 2000. These days, we have the chance for applying to the mass-production. This project constructed the system for applying the lead free solders on consumer electronic products, which is one of the major products of the LG Electronics. To select the lead free solders with corresponding to the product features, we have passed through the test and applied with Sn-3.0Ag-0.5Cu alloy system to our products, and for the application to the high melting temperature composition, we secured the thermal resistance of the many parts and substrate and optimized the processing conditions. We have operated the temperature cycling test and the high temperature storage test under the standards to confirm the reliability of the products. On these samples, we considered the consequence of our decision by the operating test. For the long life time of the product, we have operated the temperature cycling test at $-45^{\circ}C\;-\;+125^{\circ}C$, 1 cycle/hour, 1000 cycles. Also we have tested the tin whisker growth about lead free plating on lead finish. We have analyzed with the SEM, EDS and any other equipment for confirming the failure mode at the joint and the tin whisker growth on lead free finish.