Flexible BaTiO3 films as dielectric materials for high energy density capacitors were deposited on polyethyleneterephthalate (PET) substrates by r.f. magnetron sputtering. The growth behavior, microstructure and electrical properties of theflexible BaTiO3 films were dependent on the sputtering pressure during sputtering. The RMS roughness and crystallite size ofthe BaTiO3 increased with increasing sputtering pressure. All BaTiO3 films had an amorphous structure, regardless of thesputtering pressures, due to the low PET substrate temperature. The composition of films showed an atomic ratio (Ba:Ti:O)of 0.9:1.1:3. The electrical properties of the BaTiO3 films were affected by the microstructure and roughness. The BaTiO3 filmsprepared at 100mTorr exhibited a dielectric constant of ~80 at 1kHz and a leakage current of 10−8A at 400kV/cm. Also, filmsshowed polarization of 8µC/cm2 at 100kV/cm and remnant polarization (Pr) of 2µC/cm2. This suggests that sputter depositedflexible BaTiO3 films are a promising dielectric that can be used in high energy density capacitors owing to their high dielectricconstant, low leakage current and stable preparation by sputtering.

The microstructure evolution during sintering of the W-5 wt.%Cu nanocomposite powders was investigated for the purpose of developing a high density W-Cu alloy. The W-5 wt.%Cu nanopowder compact, fully-densified during sintering at 1623 K, revealed a homogeneous microstructure that consists of high contiguity structures of W-W grains and an interconnected Cu phase located along the edges of the W grains. The Vickers hardness of the sintered W-5 wt.%Cu specimen was Hv much higher than that ( Hv) of the conventional heavy alloy. This result is mostly due to the higher contiguity microstructure of the W grains compared to the conventional W heavy alloy.

TiO2 thin films for high energy density capacitors were prepared by r.f. magnetron sputtering at room temperature.Flexible PET (Polyethylene terephtalate) substrate was used to maintain the structure of the commercial film capacitors. Theeffects of deposition pressure on the crystallization and electrical properties of TiO2 films were investigated. The crystal structureof TiO2 films deposited on PET substrate at room temperature was unrelated to deposition pressure and showed an amorphousstructure unlike that of films on Si substrate. The grain size and surface roughness of films decreased with increasing depositionpressure due to the difference of mean free path. X-ray photoelectron spectroscopy (XPS) analysis revealed the formation ofchemically stable TiO2 films. The dielectric constant of TiO2 films was significantly changed with deposition pressure. TiO2films deposited at low pressure showed high dissipation factor due to the surface microstructure. The dielectric constant anddissipation factor of films deposited at 70mTorr were found to be 100~120 and 0.83 at 1kHz, respectively. The temperaturedependence of the capacitance of TiO2 films showed the properties of class I ceramic capacitors. TiO2 films deposited at10~30mTorr showed dielectric breakdown at applied voltage of 7V. However, the films of 500~300nm thickness depositedat 50 and 70mTorr showed a leakage current of ~10−8~10−9 A at 100 V.

The electrochemical performances of an asymmetric hybrid capacitor were investigated using LiFePO4 as the positive electrode and active carbon fibers(ACF) as the negative electrode. The electrochemical behaviors of a nonaqueous hybrid capacitor were characterized by constant current charge/discharge test. The specific capacitance using LiFePO4/ACF electrode turned out to be 0.87F/cm2 and the unit cell showed excellent cycling performance. This hybrid capacitor was able to deliver a specific energy as high as 178 Wh/kg at a specific power of 1,068 W/kg.

Recently, there are many problems of service qualities such as regular-rapid-safe -comfortable transport, that was traditionally advantages in urban railway transportations. These problems cause train delays that affects consecutive schedule, capacity, operation plans, and it is hard to prevent the propagation of delay and find the recovery solution. Because the urban transport demands is continuously increased and the railway service is also expanded, the railway operation company makes efforts to improve operation performance and efficiency for passengers. In this paper, we analyse the issues and problems existing in the major operation line of high-density urban railways, and suggest the development direction of intelligent operation technology to improve the urban railway service by minimizing the occurrence and propagation of delay. And the result of numerical case study is also presented.

유산균을 고농도로 배양하기 위하여 CaCO3를 각각 15%와 20%씩 첨가하여 직경이 서로 다른 CaCO3-alginate beads를 제조한 후, lactic acid에 대한 CaCO3-alginate beads의 반응 특성과 완충효과를 관찰하였으며, lactic acid에 대하여 완충작용이 있는 CaCO3-alginate beads를 이용하여 S. thermophilus ST-Body 1과 L. amylovorus DU-21을 고농도 배양하여 직접투입식 starter를 제조하였다. 본 연구에서 제조된 CaCO3-alginate beads는 CaCO3, alginate 함량 및 수분 함유율이 beads에 일정하게 고루 분포되어 있으며, 일정한 밀도를 갖는 입자임을 알 수 있었다. 또한 lactic acid에 대한 beads의 반응은 표면으로부터 일어나기 시작하여 내부로 진행됨을 확인하였으며, CaCO3-alginate beads 양의 증가는 결국 lactic acid와 반응할 수 있는 CaCO3 표면적의 증가를 가져오게 되며, 단위시간당 lactic acid와 반응하는 CaCO3의 상대적 증가를 가져오기 때문에 CaCO3-alginate beads 양의 증가는 lactic acid 용액 내부의 중화작용의 증가를 가져온다는 것을 확인하였다. 즉, CaCO3-alginate beads의 직경이 작을수록, 내부의 CaCO3 함량이 높을수록, 단위 부피당 넓은 표면적과 높은 중화작용을 가지므로 CaCO3-alginate beads를 pH neutralizer로 이용하여 유산균을 배양할 경우에는 CaCO3 함량이 높고 직경이 작은 CaCO3-alginate beads의 이용이 유산균 배양에 효과적임을 알 수 있었다. CaCO3-alginate beads를 이용한 유산균의 고농도 배양 시, pH와 생균수와의 상관성과 선형관계를 단순회귀분석법(simple regression)을 이용하여 최소자승추정량(least square estimator; LSE)을 구하여 검증한 결과, 각 X의 회귀계수의 값은 통계적으로 유의한 결과(p<0.05, p<0.01)를 보였다. 또한 R2 값은 S. thermophilus ST-Body 1와 L. amylovorus DU-21의 경우, CaCO3-alginate beads 무첨가구와 첨가구에서 각각 0.6310, 0.7505, 0.7452, 0.7609이였다. 이는 pH가 균 증식에 다소나마 영향을 주는 것을 나타낸다. 고농도로 배양된 S. thermophilus ST-Body 1과 L. amylovorus DU-21 균주를 이용하여 직접투입식 starter를 제조한 결과, 동결건조 보호제로 15% glycerol을 이용하였을 때 각각 91.96±1.35%와 89.09±4.49%의 생존율을 보였다. 본 연구에서 확립된 기법은 probiotics 조제나 정장제 조제방법에 있어서도 공히 적용 가능하므로 미생물 세포의 이용기법으로 그 생존율과 발효에 연관되는 기능보존과 수반되는 여러 분야에 적용한다는 면에서 산업적으로 중요하다고 사료된다.

For the purpose of obtaining basic information on the development of lead-free materials, a high density composites (a) W-Cu, (b) W-Sn (c)W-Cu-Sn and (d) W-Cu-Ni were fabricated by the P/M method. The particle size of used metal powders were under 325 mesh, inner size of compaction mould was mm, and compaction pressure was 400 MPa. A High density composite samples were sintered at a temperature between and for 1 hour under Ar atmosphere. The microstructure, phase transformation and physical properties of the sintered samples were investigated. As the results, the highest relative density of 95.86% (10.87 g/) was obtained particularly in the sintered W-Cu-Sn ternary system sample sintered at 450 for 1hr. And, Rockwell hardness (HRB) of 70.0 was obtained in this system.

본 연구는 2001년부터 2003년까지 '후지'/M.9가 재식된 밀식사과원에서 적정 수세와 적정 착과량을 조사하였다. 엽과비는 평균 과중(y=1.715x+205.02, R2=0.66**)과 수량(y=-35.156x+5963.7, R2=0.44**)에서 고도로 유의한 상관이 있는 것으로 나타났고, 주당엽수와 평균 과중 또한 상관이 있었다. 그러나 착과량에 따른 수체생육, 과실품질 요인중 당도 및 착색도에서는 처리간 차이가 없었다. 격년결실이 발생하지 않으면서 300g 이상의 과실을 생산하는 기준은 엽과비는 55 수준에서 착과량이 주당 약 55~64개의 수준이 적합하였다. '후지'/M.9 밀식재배시 성목기의 안정된 수세 기준은 평균 신초장이 20~25cm, 신초 정지율이 95% 이상수준을 보여야 되는 것으로 판단되며, 보다 세부적으로는 2차 생장이 거의 발생되지 않으며 과대지 비율은 적어도 20~30% 정도 되어야 할 것으로 판단되었다.

The transformation of the liquid crystal complex made by binding of anionic surfactant, sodium dodecyl sulfate (SDS), into high charge density cationic polymer, the homopolymer of diallyldimethylammonium chloride (PDADMAC) was induced by adding of nonionic surfactants and investigated by means of microscopy and FE.SEM. Among nonionic surfactants in this experiments polyethylene glycol (3 mol) ether of lauryl alcohol (laureth-3) made variation in the complex. The laureth-3 transformed the complex into spherulite vesicle with the size of ca.100μm. This change increased the viscosity and the turbidity of the solution phase separated originally. Microscope showed that they are spherulite particles and polarized microscope suggested they are multi.lamellar liquid crystals. FE-SEM also proved that explicitly.

Copper infiltration is demonstrated as a viable solution to achieve higher mechanical properties by filling the interconnected porosities of a ferrous structure with copper infiltrant. This paper will present the results of a design of experiments study based on the selected processing variables in the copper infiltration process. The variables are the following: Infiltrating temperatures, infiltrating time at pre-heat zone and hot zone, the green density of iron part, the migration of copper into the iron part at different processing conditions. The results show the flexibility of the infiltration process to attain certain mechanical properties by changing the processing conditions.

The achievement of high density at reasonable cost is one of the major challenges of the P/M industry. One of the key factors contributing to the compressibility of a mix is the lubricant. New experimental lubricants enabling higher green density by conventional compaction or temperature-controlled die compaction were identified. The compaction and ejection characteristics of these new lubricants as measured with a fully instrumented lab press are presented and compared to that of conventional lubricants.

This paper will describe a powder and processing method that facilitates single press-single sintered densities approaching 7.5 g/cm³. At this sintered density, mechanical properties of the powder metal (P/M) component are significantly improved over current P/M technologies and begin to approach the performance of wrought steels. High performance gears have the added requirement of rolling contact fatigue durability that is dependent upon localized density and thermal processing. Combining high density processing of engineered P/M materials with selective surface densification enables powder metal components to achieve rolling contact fatigue durability and mechanical property performance that satisfy the performance requirements of many high strength automotive transmission gears. Data will be presented that document P/M part performance in comparison to conventional wrought steel grades.

For attaining optimum fatigue resistance of PM steels, high density levels are necessary. In this work, sintered steels Fe-1.5%Mo-0.6%C and Fe-1.5%Cr-0.2%Mo-0.6%C were produced with density levels of 7.1 to . Ultrasonic fatigue testing with 20 kHz was performed in push-pull mode up to 10E9 cycles. It was shown that the fatigue endurance strength is strongly improved by higher density levels, but also higher sintering temperatures are beneficial. The Cr-Mo steels proved to be superior to the plain Mo alloyed, due to a more favourable as-sintered matrix microstructure.

In this experimental work, the development of a multicomponent binder system based on high density polyethylene (HDPE) and paraffin wax for Powder Injection Molding of Alumina parts was carried out. The optimum composition of the injection mixture was established through mixing torque measurements and a rheological study. The maximum powder loading was 58 vol%. The miscibility of organic components and the optimum injection temperature was evaluated by thermal characterization of binder and feedstock. The thermal debinding cycle was developed on the basis of thermogravimetrical analysis of the binder. After sintering the densities achieved were closed to 98% of the theoretical one.