• 한국생물공학회:학술대회논문집
• /
• 2003.04a
• /
• pp.513-516
• /
• 2003

고체상 풀림과 재접힘 공정을 통해서 EK의 활성이 회복되어지는 것을 확인할 수 있었다. 이는 고정화 효소를 사용함으로써 기존의 액상반응에서 불가능한 효소의 재사용 문제를 해결할 수 있다. 친화도보다는 다중 공유결합을 통한 효소의 고정화가 효소의 활성 회복에 높은 안정성을 가질 수 있다고 예상한다.

• The Korean Journal of Rheology
• /
• v.8 no.2
• /
• pp.119-128
• /
• 1996

폴리프로필렌(PP)/폴리카보네이트(PC) 블렌드의 유변학적 고찰을 통해 블렌드의 수 축현상과 분상상의 변형의 연관성을 연구했다. 블렌드의 수축현상은 압축과정에서 변형됐던 분산상이 고온에서 다시 원래의 무변형 상태로 복귀하면서 나타나는 탄성변형의 풀림으로 추정되고 압출팽윤의 데이터와도 부합된다. 압출온도를 최대한 낮게 해서(25$0^{\circ}C$) 제조한 블 렌드의 경우가 최대한 높게 한 경우 (29$0^{\circ}C$)보다 수축이더 큰 사실을 설명하기 위하여 순수 PC와 PP의 전단점도비와 신장점도비를 측정 비교한 결과 두 값이 공히 높은 온도의 경우 가 오히려 작게 되어 점성에 의한 분산상의 전단변형이나 신장변형이 수축의 원인이 아니라 는 것을 알아다. 한편 법선응력과 전단응력의 데이터로부터 얻은 물질풀림시간의 비는 낮은 온도의 경우가 작아서 수축현상이 분산상의 탄성에 의한 변형이라는 것을 확인했다.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.7
• /
• pp.69-77
• /
• 1998

Development on the mechanical properties of steel sheet for the automobile body panel is very important in the BAF(Batch annealing furnace) annealing process. Because of the heat treatment method in the BAF, mechanical properties were decided on the heat treatment method of the coil. So, we tested on the development of mechanical properties according to heat treatment method at the annealing furnace using the In atmospheric gas($H_2$ : 75%, $N_2$ : 25%) and the HNx atmospheric gas($H_2$ : 5%, $N_2$ : 95%) We confirmed the following characteristics, mechanical properties were changed under the influence of the annealing cycle and the atmospheric gas. And, we have some result according to heat treatment method. Elongation of the mechanical properties in the HNx BAF is higher than the Ax BAF. But tensile strength and hardness is higher than the HNx BAF.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.26 no.3
• /
• pp.273-283
• /
• 2010

This study evaluated the effect of 3 different compatible screws on the detorque values in a multiple implant-supported superstructure and single implant abutments. An implant superstructure directly connected to 4 implants was screwed to 6 experimental dental stone casts made by acrylic resin splinted impressions, using 20 Ncm. The detorque values of screws were measured twice. Three compatible abutment screws used in this study were TorqTite screw, Gold-Tite screw, and, Titanium screw. And, using single implant abutments (GoldAdapt Engaging abutments), the detorque values of 3 different screws were measured twice on 2 implants of 5 experimental casts. According to statistical analysis of detorque values using mixed model at a .05 level of significance, no statistically significant differences among 3 different compatible screws were found in a multiple implant-supported superstructure (p>0.05). But, in single implant abutments, statistically significant differences among 3 different compatible screws were found (p=0.0175). The detorque values of TorqTite(p=0.0462) and Titanium(p=0.0348) screws were significantly higher than those of Gold-Tite screw, but no statisticantly significantlydifferences were found between TorqTite and Titanium screws(p>0.05). Therefore, various compatible screws showed significant effects on the detorque values for single implant abutment, but, showed no significant effects for a multiple implant-supported superstructure.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.06a
• /
• pp.511-512
• /
• 2007

• Journal of the Korean Ceramic Society
• /
• v.39 no.11
• /
• pp.1090-1096
• /
• 2002

Six different composition of water-swellable bentonite rheology modifiers(WSB-1~WSB-6) were prepared by the compounding of peptizers and anionic surfactants as an additives with Bentonite(BEN) of montmorillonite group. Average particle size, particle morphology and water-swellability of WSB and the viscosity with additives were measured, respectively. And the rheological behavior of WSB were investigated using the rheometer. The viscosity of WSB-1 increased with decreasing both pH and average particle size of BEN, WSB-2 treated $Na_2CO_3$ as a peptizer showed the maximum viscosity. These results can be interpretated cause for rearrangment as the edge-to-face structure of BEN particles containing WSB. Also, WSB-4∼WSB-6 containing both peptizer and anionic surfactant was sol phase that their viscosity was not nearly with the shear rate, however, WSB-3 containing Tetrasodium Pyrophosphate(TSPP) as an anionic surfactant showed the thixotropy by the viscosity difference of 1000 times with the shear rate. From this result, the anions of TSPP can be explained to arrange in edge of BEN particles containing WSB-3.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.24-24
• /
• 2003

최근 자동차 산업이 발달함에 따라 철강업계와 자동차 회사에서는 전에 많이 사용하던 내연 무도금강판 대신 부식에 저항력이 강한 도금강판을 사용한 이후로 냉연강판의 가공 시에 야기되지 않았던 많은 문제점들이 나타났다 자동차용 강판의 경우 판재의 체적에 비하여 금형과 판재의 접촉면적이 큰 프레스 공정에서는 판재의 표면에 작용하는 마찰력의 크기가 판재의 스탬핑 성형성에 큰 영향을 미친다. 이는 마찰특성이 비록 재료고유의 성형한계에서는 영향을 미치지 못하나 스탬핑 공정에 있어서 금형과의 접촉면에서 마찰력의 크기가 패널의 변형률분포를 변화시켜 스탬핑 성형성에 큰 영향을 주는 것이다. 따라서 본 연구는 자동차용 도금강판의 표면 거칠기에 따른 판재의 표면 마찰 특성 변화를 알아보았다. 소재의 기계적 특성 측정은 UTM을 사용하였고, 도금층은 XRD, SEM을 이용하여 상분석 하였으며, 표면 거칠기는 AFM(Atomic Force Microscope), SJ-400(Mitutoyo)을 사용하여 표면 거칠기를 측정하였다. 또 드로잉 하중을 비드부에서의 굽힘-굽힘 풀림 소성변형에 의한 변형력 성분과 마찰력 성분으로 분리하여 강판의 쿠롬 마찰계수를 DBS(Draw bead simulation)로 측정하였다.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.4
• /
• pp.111-117
• /
• 1998

In order to increase productivity of an assembly system composed of multiple robots along a conveyer line, an efficient sequence planning is necessary because the assembly time is dependent upon the assembly sequence. In this paper, a two-robot assembly system is considered in which two robots operate simultaneously and transfer parts from the part feeders to the workpiece on the conveyer one by one. In this case, the distance from the feeder to the workpiece varies with time because the workpiece moves at a constant speed on the conveyer. Hence, the sequence programming is not a trivial problem. Also, the two robots may interfere with each other kinematically and dynamically due to the simultaneous operation, so the sequence should be programmed to avoid the interferences. In this paper, the task sequence optimization problem is formulated and is solved by employing the simulated annealing which has been shown to be effective for solving large combinatorial optimizations.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.2
• /
• pp.108-114
• /
• 1998

Development on the mechanical properties of steel sheet for the automobile body panel is very important in the BAF(Batch annealing furnace) annealing process. Because of the heat treatment method in the BAF, mechanical properties was decided on the heat treatment method of the coil. So, we tested on the development of mechanical properties according to heat treatment method at the annealing furnace using the Ax(H$_2$75%, $N_2$25%) atmospheric gas and the HNx(H$_2$4%, $N_2$96%) atmospheric gas. As a result of several investigations. We confirmed the following characteristics ; mechanical properties was changed under the influence of the annealing cycle, the heat treatment method and the atmospheric gas. And, elongation in the HNx BAF was better than the Ax BAF. Finally, most important thing in the BAF is using of proper annealing cycle in order to get a good quality.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.10
• /
• pp.52-59
• /
• 2002

The thermo-mechanical characteristics of high temperature NITINOL shape memory alloy were evaluated using DSC with small samples and DMA with three-point bending specimens. The shape memory alloy of 54.4Ni/45.5Ti wt.% was used so that the phase transformation temperatures were in the range of 50~11$0^{\circ}C$. Two types of sample were tested in the experiments corresponding to as-received and annealed conditions. Simple beam bending theory was used to calculate the dynamic moduli of the shape memory alloy. According to the results, a large discrepancy in transformation temperatures was found between DSC and DMA techniques. Annealing treatment was found to suppress the R-phase transformation during cooling and the secondary plateau in the austenite transformation. Such a heat treatment was also significantly influenced to raise the transformation temperatures and the moduli of the shape memory alloy.