Embryonic compaction is essential for normal preimplantation development in mammals. The present study was to investigate the effects of compaction patterns on developmental competence of pig embryos. The proportion of blastocyst formation derived from compacted morula was higher than those of compacting and pre-compacting morula (P<0.01). Nuclei numbers of inner cell mass (ICM), trophectoderm (TE), and total of blastocysts derived from compacted group were also superior to those of compacting and pre-compacting groups (P<0.05). Then, compaction patterns, developmental ability and structural integrity were compared between mono- and poly-spermic embryos. The rate of compacted morula in mono-spermic embryos was higher than that of poly-spermic embryos (P<0.05). Especially, the rate of blastocyst formation derived from compacted embryos in mono-spermic embryo group was higher than that of poly-spermic embryo group (P<0.05), although no difference was detected between the two groups in the structural integrity. Finally, we confirmed that beta-catenin was differentially expressed according to compaction patterns in morula and blastocyst stage embryos. In conclusion, our results suggest that the compaction patterns during preimplantation development play a direct role in developmetal competence and quality of pig embryos.

The first morphogenetic event of preimplantation development, compaction, was required efficient production of porcine embryos in vitro. Compaction of the porcine embryo, which takes place at post 4-cell stage, is dependent upon the adhesion molecule E-cadherin. The E-cadherin through -catenin contributes to stable cell-cell adhesion. Rho-associated kinase (ROCK) signaling was found to support the integrity of E-cadherin based cell contacts. In this study, we traced the effects of ROCK-1 on early embryonic development and structural integrity of blastocysts in pigs. Then, in order to gain new insights into the process of compaction, we also examined whether ROCK-1 signaling is involved in the regulation of the compaction mediated by E-cadherin of cellular adhesion molecules. As a result, real-time RT-PCR analysis showed that the expression of ROCK-1 mRNA was presented throughout porcine preimplantation stages, but not expressed as consistent levels. Thus, we investigated the blastocyst formation of porcine embryos treated with LPA and Y27632. Blastocysts formation and their qualities in LPA treated group increased significantly compared to those in the Y27632-treated group (p < 0.05). Then, to determine whether ROCK-1 associates embryonic compaction, we explored the effect of activator and/or inhibitor of ROCK-1 on compaction of embryos in pigs. The rate of compacted morula in LPA treated group was increased compared to that in the Y27632-treated group (39.7 vs 12.0%). Furthermore, we investigated the localization and expression pattern of E-cadherin at 4-cell stage porcine embryos in both LPA- and Y27632-treated groups by immunocytochemical analysis and Western blot analysis. The expression of E-cadherin was increased in LPA-treated group compared to that in the Y27632-treated group. The localization of E-cadherin in LPA-treated group was enriched in part of blastomere contacts compared to that Y27632-treated group. ROCK-1 as a crucial mediator of embryo compaction may plays an important role in regulating compaction through E-cadherin of the cell adhesion during the porcine preimplantation embryo. We concluded that ROCK-1 gene may affect the developmental potential of porcine blastocysts through regulating embryonic compaction.

3-D shape soft magnetic composite parts can be formed by general compaction method of powder metallurgy. In this study, the results on the high density nanostructured Fe-Si/Fe composite prepared by a warm compaction method were presented. Ball-milled Fe-25 wt.%Si powder, pure Fe powder and Si-polymer were mixed and then the powder mixture was compacted at various temperatures and pressures. Pore free density of samples up to 95% theoretical value has been obtained. The warm compacted sample prepared at 650 MPa and 240℃ had highest compaction properties in comparison with other compacts prepared at 300, 400 MPa and room temperature and 120℃. The magnetic properties such as core loss, magnetization saturation and coercivity were measured by B-H curve analyzer and vibration sample magnetometer.

The compaction response of nano powders with an addition of Ti powders prepared by magnetic pulsed compaction and subsequent sintering processes was investigated. All kinds of different bulk exhibited an average shrinkage of about 12% for different MPCed pressure and sintering temperature, which were approximately 50% lower than those fabricated by general process (20%) and a maximum density of around 92.7% was obtained for 0.8GPa MPCed pressure and sintering temperature. The addition of Ti powder induced an increase in the formability and hardness of the sintered . But the lower densities were obtained on sintering with addition of over 10 (wt%) Ti powder due to generation of crack during sintering. Subsequently it was verified that the optimum compaction pressure in MPC and sintering temperature were 0.8GPa and , respectively

본 연구에서는 시공시 현장다짐관리에 있어 단위중량을 이용하는 기존의 방법 대신 탄성계수와 같은 역학적 특성을 이용하는 새로운 다짐관리기준 정립을 위한 현장시험방법을 제시하고자 한다. 이를 위하여 시험법이 간편하며, 활용성이 증가하고 있는 동적콘관입시험인 DCPT 측정시험이 노상토의 다짐품질관리의 적용이 가능한지를 검토하였다. DCPT 시험방법이 현장에서 다짐후 설계탄성계수를 추정할 수 있는지를 확인하기 위하여 실내토조시험, 현장시험을 실시하였고, 노상층의 DCPT, CBR, 회복탄성계수간의 상관관계를 분석하였다. 또한, 문헌조사 분석을 통하여 DCPT 시험간격을 제시하였다. 실내시험결과를 분석한 결과, DCPT 관입치 (PR) 값과 CBR값 간의 상관관계식에서는 Livneh 식이 가장 부합됨을 알 수 있었고, DCPT 시험을 통한 PR값을 국내외 탄성계수 추정식을 평가한 결과, 예측 MR 탄성계수 값과 부합하는 제안식으로는 George와 Pradesh의 식이 있었으며, FWD를 이용한 MR 제안식을 비교한 결과, Cudishala의 제안삭은 예측 MR 값보다 다소 크게 산정되며, Chen의 제안식의 경우 다소 작은 값을 보이고, 건설기술연구원의 제안식은 예측 MR값에 과소 평가함을 알 수 있었다. 그러나 실제 차량이 유발하는 주행속도에 따른 축차응력과 구속응력으로부터 실내 MR 시험결과를 비교분석한 결과, 건기원 제안식이 가장 적합함을 알 수 있었다. DCPT 현장시험결과를 분석한 결과, 관입지점의 입도분포에 따라 PR 값에 오차가 생길 수 있음을 알 수 있었고, 오차를 감소하기 위한 DCPT 시험간격에 대한 추천값을 제시하였다. 현장시험결과를 분석한 결과 현장 다짐도를 만족하는 노상이라 하여도 노상 재료에 따라 평균 PR 값이 다르게 나타났으며, 특히 입경이 큰 재료일수록 평균 PR 값이 작음을 알 수 있었고, 현장함수비의 경우 다짐도에 미치는 영향은 상당히 크나, DCPT 시험에 있어서 현장함수비 변화는 평균PR값에 미치는 영향이 미미함을 알수 있었다.

This article presents the successful consolidation of the mixed Co and Diamond powders for a drilling segment by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their properties were analyzed. Homogeneous hardness (Hv 220) and density (97%) of sintered bulks fabricated by MPC were obtained by the new technique, where higher pressure has been employed for short period of time than that of general process. A fine microstructure and homogeneous hardness in the consolidated bulk were observed without cracks. Relatively higher drilling speed of 9.61 cm/min and life time of 6.55 m were found to the MPCed specimens, whereas the value of the specimens fabricated by general process was 11.71 cm/min and 7.96 m, respectively. A substantial improvement of mechanical properties of segment was achieved through this study.

In this research, fine-structure TiO2 bulks were fabricated in a combined application of magnetic pulsed compaction (MPC) and subsequent sintering and their densification behavior was investigated. The obtained density of TiO2 bulk prepared via the combined processes increased as the MPC pressure increased from 0.3 to 0.7 GPa. Relatively higher density (88%) in the MPCed specimen at 0.7 GPa was attributed to the decrease of the inter-particle distance of the pre-compacted component. High pressure and rapid compaction using magnetic pulsed compaction reduced the shrinkage rate (about 10% in this case) of the sintered bulks compared to general processing (about 20%). The mixing conditions of PVA, water, and TiO2 nano powder for the compaction of TiO2 nano powder did not affect the density and shrinkage of the sintered bulks due to the high pressure of the MPC.

Sintering behavior of iron nanopowder agglomerate compact prepared by slurry compaction method was investigated. The Fe nanopowder agglomerates were prepared by hydrogen reduction of spray dried agglomerates of ball-milled nanopowder at various reduction temperatures of , and , respectively. It was found that the Fe nanopowder agglomerates produced at higher reduction temperature have a higher green density compact which consists of more densified nanopowder agglomerates with coarsed nanopowders. The sintering behavior of the Fe nanopowder agglomerates strongly depended on the powder packing density in the compact and microstructure of the agglomerated nanopowder. It was discussed in terms of two sintering factors affecting the entire densification process of the compact.

The objective of the present study is to investigate the increase in the functional characteristics of a substrate by the formation of a thin coating layer. Thin coating layers of have high potential because exhibits high hardness. Shock induced reaction synthesis is an attractive fabrication technique to synthesize uniform coating layer by controlling the shock wave. Ti and Si powders to form using shock induced reaction synthesis, were mixed using high-energy ball mill into small scale. The positive effect of this technique is highly functional coating layer on the substrate due to ultra fine substructure, which improves the bonding strength. These materials are in great demand as heat resisting, structural and corrosion resistant materials. Thin coating layer was successfully recovered and showed high Vickers' hardness (Hv=1183). Characterization studies on microstructure revealed a fairly uniform distribution of powders with good interfacial integrity between the powders and the substrate.

This article presents the challenges toward the successful consolidation of nanopowder using magnetic pulsed compaction (MPC). In this research the ultrafine-structured bulks have been fabricated by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their properties were investigated. The obtained density of bulk prepared by the combined processes was increased with increasing MPC pressure from 0.5 to 1.25 GPa. Relatively higher hardness and fracture toughness in the MPCed specimen at 1.25 GPa were attributed to the retention of the nanostructure in the consolidated bulk without cracks. The higher fracture toughness could be attributed to the crack deflection by homogeneous distribution and the retention of nanostructure, regardless of the presence of porosities. In addition, the as consolidated bulk using magnetic pulsed compaction showed enhanced breakdown voltage.

Characteristics of Al-based composites with waste stainless steel short fiber, fabricated by magnetic pulsed compaction and sintering were investigated. The compacts prepared by magnetic pulsed compaction showed high relative density and homogeneous microstructure compared with that by conventional press compaction. The relative density of sintered composites at for 1 h exhibited the same value with compacts and decreased with increase in STS short fiber content. The reaction between Al and STS phase was confirmed by the microstructural analysis using EDS. The sintered composites, prepared by magnetic pulsed compaction, showed increased hardness value with increasing STS fiber content. Maximum yield strength of 100 MPa and tensile strength of 232 MPa were registered in the AI-based composite with 30 vol% STS short fiber.

In recent years, a rapid increase in demands for the soft magnetic composite parts has been created and it has been tried to improve their properties by various processing methods, alloying elements and compaction parameters. Warm compaction method has been used for the reduction of residual stress, the improvement of magnetic properties and the higher densities. In this work, the effects of warm compaction and polymer binder on magnetic properties of Fe powder core were investigated. The sintering powder, Fe oxide, was ball-milled for 30n hours. And then ball-milled Fe oxide powder was reduced through hydrogen reduction process. The hydrogen reduced Fe powder and polymer binder were mixed by 3-D turbular mixer. And then the mixed powder was warm-compacted. The magnetic properties such as core loss and permeability were measured by B-H curve analyzer.