현재, 교통안전진단의 경우 차량 및 보행자의 교통사고를 미연에 방지하고 도로의 전체적인 안전을 도모하고자, 교통안전법 제34조 에 의거하여, 수행 조건에 부합한 경우 교통안전진단을 받도록 규정하고 있다. 교통안전진단의 경우 도로의 구분에 따라 다른 기준을 적용하고 있으며, 도로별 길이를 기준으로 수행 여부를 판단하고 있다. 교통안전진단의 경우 도로의 설계단계, 개시 전 단계 및 운영단계 등 3가지로 구분되어 수행되고 있으며, 각각의 단계별로 진단 수행 내용 및 범위가 조금씩 다르게 진행된다. 설계 단계에서의 교통안전진단의 경우, 해당 도로의 실시 설계 내용을 바탕으로 도로의 안전 을 판단하며, 개시 전 단계의 경우 도로의 신설 이후 운영 전 도로의 안전을 평가한다. 마지막으로 운영 단계의 교통안전진단의 경우 현재 운영 중인 도로에 대하여 도로의 안전을 평가하는 것이다. 본 연구에서는 진단단계별 교통안전진단 중 도로 설계단게에서 수행 시 발생될 수 있는 한계점을 파악하고, 이를 보완할 수 있는 방 안을 제시하여 그 효과를 분석하고자 한다. 또한, 국제 기준으로 운영되고 있는 iRAP(International Road Assessment Programme)의 SR4D( Star Rating for Design)을 통해 설계단계의 교통안전진단 수행 시 효과적이고 안전한 진단결과를 도출해내고자 한다.

An in-wheel motor is a system in which a drive motor is mounted inside a wheel along with a braking device, and the motor inside the wheel directly drives the wheel. An SR motor drive in replace of the conventional PM motor drive for in-wheel motor system has been proposed and analyzed. Two different types of converters were selected and their feasibility in terms of different current control schemes was analyzed and validated through dynamic simulation using PSIM software.

The effects of La3+ substitution for Sr2+-site on the crystal structure and the dielectric properties of (Ba0.7Sr0.3-3x/2Lax) (Ti0.9Zr0.1)O3 (BSLTZ) (0.005 ≤ x ≤ 0.02) ceramics were investigated. The structural characteristics of the BSLTZ ceramics were quantitatively evaluated using the Rietveld refinement method from X-ray diffraction (XRD) data. For the specimens sintered at 1,550 °C for 6 h, a single phase with a perovskite structure and homogeneous microstructure were observed for the entire range of compositions. With increasing La3+ substitution (x), the unit cell volume decreased because the ionic size of La3+ (1.36 Å) ions is smaller than that of Sr2+ (1.44 Å) ions. With increasing La3+ substitution (x), the tetragonal phase fraction increased due to the A-site cation size mismatch effect. Dielectric constant (εr) increased with the La3+ substitution (x) due to the increase in tetragonality (c/a) and the average B-site bond valence of the ABO3 perovskite. The BSLTZ ceramics showed a higher dielectric loss due to the smaller grain size than that of (Ba0.7Sr0.3)(Ti0.9Zr0.1)O3 ceramics. BSLTZ (x = 0.02) ceramics met the X7R specification proposed by the Electronic Industries Association (EIA).

This study investigated the growth behavior and characteristics of compounds formed at the interface between a liquid Al-Si-Cu alloy and solid cast iron. Through microstructural analyses, it was observed that various AlFe and AlFeSi phases are formed at the interface, and the relative proportion of each phase changes when small amounts of strontium are added to the Al alloy. The results of the microstructural analysis indicate that the primary phases of the interfacial compounds in the Al-Si-Cu base alloy are Al8Fe2Si and Al4.5FeSi. However, in the Sr-added alloys, significant amounts of binary AlFe intermetallic compounds such as Al5Fe2 and Al13Fe4 formed, in addition to the AlFeSi phases. The inclusion of Sr has a slight diminishing effect on the rate at which the interfacial compounds layer thickens during the time the liquid Al alloy is in contact with the cast iron. The study also discusses the nano-indentation hardness and micro-hardness of the interfacial phases.

Noise is a sound that people don't want. In this study, noise is measured for SR20, a general aviation trainer used in Korea. In addition, noise measurement points are selected at Muan Airport, where most of the domestic trainers fly under the supervision of the Ministry of Land, Infrastructure and Transport, and the measured data are analyzed based on this. We also want to analyze the noise characteristics of SR20 aircraft through frequency analysis of the noise characteristics of SR20 aircraft are unique. We want to use this to understand what type of noise the trainer affects in future studies. this study will improve the reliability of the noise prediction scenario by comparing and analyzing the actual measured and predicted values when using the noise prediction program.

In this article, Pb2Ba1.7Sr0.3Ca2Cu3O10+δ superconductor material was synthesized using conventional solid-state reaction method. X-ray diffraction (XRD) analysis demonstrated one dominant phase 2223 and some impurities in the product powder. The strongest peaks in the XRD pattern were successfully indexed assuming a pseudo-tetragonal cell with lattice constants of a = 3.732, b = 3.733 and c = 14.75 Å for a Pb-Based compound. The crystallite size and lattice strain between the layers of the studied compound were estimated using several methods, namely the Scherrer, Williamson-Hall (W.H), sizestrain plot (SSP) and Halder Wagner (H.W) approach. The values of crystallite size, calculated by Scherrer, W.H, SSP and H.W methods, were 89.4540774, 86.658638, 87.7555823 and 85.470086 Å, respectively. Moreover, the lattice strain values obtained by W.H, SSP and H.W methods were 0.0063240, 0.006325 and 0.006, respectively. It was noted that all crystallite size results are consistent; however, the best method is the size-strain plot because it gave a value of R2 approaching one. Furthermore, degree of crystallites was calculated and found to be 59.003321%. Resistivity analysis suggests zero-resistance, which is typical of superconducting materials at critical temperature. Four-probe technique was utilized to measure the critical temperature at onset Tc(onset), zero resistivity Tc(off set), and transition (width ΔT), corresponding to temperatures of 128 K, 116 K, and 12 K, respectively.

This study is related to the development of lightweight automotive materials that were carried out to develop eco-friendly vehicles worldwide. High-strength aluminum alloy is used as one of the significant lightweight materials in the field of transportation machinery, and it is used as a lightweight material in various areas, including automobiles. The A356 alloy used in this study is an excellent aluminum alloy material that has widely used as a high strength aluminum alloy material in various forming methods. In this study, to examine the characteristics of the two alloys in which Mn and Sr elements were added to the A356 alloy and the A356 alloy, both alloys were manufactured by metal mold casting, which is a gravity casting method. The obtained specimens were heat-treated under the same conditions. In this study have investigated of the microstructure analysis, thermal analysis, crystal phase analysis, and mechanical property evaluation were performed to confirm how the added Mn and Sr elements influenced the microstructure, precipitate formation, and mechanical properties.

NKN [(Na,K)NbO3] is a candidate lead-free piezoelectric material to replace PZT [Pb(Zr,Ti)O3]. A single crystal has excellent piezoelectric-properties and its properties are dependent of the crystal orientation direction. However, it is hard to fabricate a single crystal with stoichiometrically stable composition due to volatilization of sodium during the growth process. To solve this problem, a solid solution composition is designed (Na,K)NbO3-Ba(Cu,Nb)O3 and solid state grain growth is studied for a sizable single crystal. Ceramic powders of (Na,K)NbO3-M(Cu,Nb)O3 (M = Ca, Sr, Ba) are synthesized and grain growth behavior is investigated for different temperatures and times. Average normal grain sizes of individual specimens, which are heat-treated at 1,125 oC for 10 h, are 6.9, 2.8, and 1.6 m for M = Ca, Sr, and Ba, respectively. Depending on M, the distortion of NKN structure can be altered. XRD results show that (NKN-CaCuN: shrunken orthorhombic; NKN-SrCuN: orthorhombic; NKN-BaCuN: cubic). For the sample heat-treated at 1,125 oC for 10 h, the maximum grain sizes of individual specimens are measured as 40, 5, and 4,000 m for M = Ca, Sr, and Ba, respectively. This abnormal grain size is related to the partial melting temperature (NKN-CaCuN: 960 oC; NKN-SrCuN: 971 oC; NKN-BaCuN: 945 oC).

The grain growth behavior of M-type Sr hexaferrite (SrM) grains is investigated with the addition of MnCO3. First, the SrM powder is synthesized by a conventional solid-state reaction. The powder compacts of SrM are sintered at 1250oC for 2 h with various amounts of MnCO3 (0, 0.5, 1.0, and 4.0 mol%). There is no secondary solid phase in any of the sintered samples. Relative density increases when MnCO3 is added to the SrM. Obvious abnormal grain growth does not appear in any of the SrM samples with MnCO3. The average grain size increases when 0.5 mol% MnCO3 is added to the SrM. However, as the amount of MnCO3 increase to over 0.5 mol%, the average grain size decreases. These observations allow us to conclude that the growth of SrM grains is governed by the two-dimensional nucleation grain growth mechanism, and the critical driving force for the growth of a grain decreases as the amount of MnCO3 increases.

There are several manufacturing techniques for developing thermionic cathodes for vacuum ultraviolet(VUV) ionizers. The triple alkaline earth metal emitters(Ca-Sr-Ba) are formulated as efficient and reliable thermo-electron sources with a great many different compositions for the ionizing devices. We prepare two basic suspensions with different compositions: calcium, strontium and barium. After evaluating the electron-emitting performance for europium, gadolinium, and yttrium-based cathodes mixed with these suspensions, we selected the yttrium for its better performance. Next, another transition metal indium and a lanthanide metal neodymium salt is introduced to two base emitters. These final composite metal emitters are coated on the tungsten filament and then activated to the oxide cathodes by an intentionally programmed calcination process under an ultra-high vacuum(~10-6 torr). The performance of electron emission of the cathodes is characterized by their anode currents with respect to the addition of each element, In and Nd, and their concentration of cathodes. Compared to both the base cathodes, the electron emission performance of the cathodes containing indium and neodymium decreases. The anode current of the Nd cathode is more markedly degraded than that with In.

We report the structural, magnetic and magnetocaloric properties of Sr1.8Pr0.2FeMo1-xWxO6(0.0 ≤ x ≤ 0.4) samples prepared by the conventional solid state reaction method. The X-ray diffraction analysis confirms the formation of the tetragonal double perovskite structure with a I4/mmm space group in all the synthesized samples. The temperature dependent magnetization measurements reveal that all the samples go through a ferromagnetic to paramagnetic phase transition with an increasing temperature. The Arrott plot obtained for each synthesized sample demonstrates the second order nature of the magnetic phase transition. A magnetic entropy change is obtained from the magnetic isotherms. The values of maximum magnetic entropy change and relative cooling power at an applied field of 2.5 T are found to be 0.40 Jkg−1K−1 and 69 Jkg−1 respectively for the Sr1.8Pr0.2FeMoO6 sample. The tunability of magnetization and excellent magnetocaloric features at low applied magnetic field make these materials attractive for use in magnetic refrigeration technology.

In order to develop a new commercial Al-12%Si casting alloy with improved physical properties, we investigated the effect of adding Sr and TiB to the alloy. Al-12%Si alloys were prepared by die casting at 660 oC. The eutectic temperature of the Sr-modified Al-12%Si alloy decreased to 9 oC and the mushy zone region increased. The shape of the Si phase changed from coarse acicula to fine fiber with the addition of Sr. The addition of TiB in the Al-12%Si alloy reduced the size of the primary α-Al and eutectic Si phases. When Sr and TiB were added together, it worked more effectively in refinement and modification. The density of twins in the Si phase-doped Sr increased and the width of the twins was refined to 5 nm. These results are related to the impurity induced twinning(IIT) growth.

The discovery of new luminescent materials for use in light-emitting diodes(LEDs) has been of great interest, since LED-based solid state lighting applications are attracting a lot of attention in the energy saving and environmental fields. Recent research trends have centered on the discovery of new luminescent materials rather than on fine changes in well-known luminescent materials. In a sense, the novelty of our study beyond simple modification or improvement of existing phosphors. A good strategy for the discovery of new fluorescent materials is to introduce activators that are appropriate for conventional inorganic compounds, that have well-defined structures in the crystal structure database, but have not been considered as phosphor hosts. Another strategy is to discover new host compounds with structures that cannot be found in any existing databases. We have pursued these two strategies at the same time using composite search technology with particle swarm optimization(PSO). In this study, using PSO, we have tracked down a search space composed of Sr-Al-Si-O-N and have discovered a new phosphor structure with yellow luminescence; this material is a potential candidate for UV-LED applications

Ce0.8Sm0.2O2–δ―Sm0.1Sr0.9Cu0.2Fe0.8O3–δ dual-phase membranes were prepared with one-pot method and citric acid sol-gel process. After calcination of the powder at 850 ℃, the dual-phase membranes were prepared by uniaxially pressing the powder. The dual-phase membranes were sintered at 1150 ℃ for 5h with heating/cooling rates of 2 ℃/min. The phase structure and microstructure of the sintered membrane were studied by XRD and SEM. Elemental analysis of the membrane surface and cross section was performed. The oxygen permeation fluxes of Cu-containing dual-phase membranes were evaluated in the temperature range of 800―950 ℃ with He and CO2 as the sweep gas.

Eu2+ 이온이 도핑된 질화물 형광체 Sr2Si5N8:Eu2+는 탄소열 환원 질화법 (Carbothermal Reduction Nitridation, CRN)을 이용하여 제조된다. X-선 회절분석기를 이용하여 구조를 관찰할 수 있다. 흡수 밴드 피크인 470 nm 는 Photoluminescence Exitation (PLE) 측정을 통해 확인할 수 있다. 이러한 여기 광은 InGaN 기반으로 한 발광다이오 드에 적용시키기에 효과적일 것으로 기대되며, (Sr1-xEux)2Si5N8:Eu2+ 형광체는 Eu2+ 이온 도핑 농도에 따라 628 nm 부터 670 nm 까지의 피크 파장을 얻을 수 있다. Eu2+의 농도가 증가할수록 발광 파장이 길어지는 적색 편이 현상을 관찰할 수 있다. 청색 발광다이오드에 Y3Al5O12:Ce3+ 형광체와 함께 적용하여 우수한 연색성을 갖는 백색광을 얻을 수 있었다.

The electrical transport properties of La0.5Sr0.5CrO3 below room temperatures were investigated by dielectric, dc resistivity, magnetic properties and thermoelectric power. Below TC, La0.5Sr0.5CrO3 contains a dielectric relaxation process in the tangent loss and electric modulus. The La0.5Sr0.5CrO3 involves the transition from high temperature thermal activated conduction process to low temperature one. The transition temperature corresponds well to the Curie point. The relaxation mechanism has been discussed in the frame of electric modulus spectra. The scaling behavior of the modulus suggests that the relaxation mechanism describes the same mechanism at various temperatures. The low temperature conduction and relaxation takes place in the ferromagnetic phase. The ferromagnetic state in La0.5Sr0.5CrO3 indicates that the electron - magnon interaction occurs, and drives the carriers towards localization in tandem with the electron - lattice interaction even at temperature above the Curie temperature.

산소 분리를 위한 세라믹 중공사막을 상전이 방적기술을 통해 제조하였다. 초기 BSCF 선구물질은 고상반응법을 이용하여 합성한 상용 분말이며, 고분자 용액에 분산시킨 후 이중관형 노즐을 통해 사출하였다. 사출된 분리막은 상전이 과정을 거친 후 건조시켰으며 중공사막의 한쪽 끝을 밀봉하였다. 한쪽 끝이 막힌 중공사막의 표면에 dip coating 방법으로 LSCF를 코팅하였으며 1100 ℃에서 소결하여 치밀성을 갖는 한쪽 끝이 막힌 LSCF coated BSCF 중공사막을 제조하였다. 분리막의 공급측은 대기 중 공기를 사용하였으며 투과측은 진공상태를 유지하였다. 투과된 기체의 유량 및 산소의 농도를 측정하였으며 장기투과 실험과 EDS 분석을 통해 분리막의 안정성 평가를 진행하였다.

산소 분리를 위한 세라믹 중공사막을 상전이 방적기술을 통해 제조하였다. Ba0.5Sr0.5Co0.8Fe0.2O3-δ 선구 물질을 고분자 용액에 분산시킨 후 이중관형 노즐을 통해 사출한 후 상전이, 건조한 후 분리막의 한쪽 끝을 밀봉하였다. La0.6Sr0.4Ti0.3Fe0.7O3-δ 코팅 층은 dip coating 방법으로 제조되었으며 최종적으로 고온에서 소결하여 La0.6Sr0.4Ti0.3Fe0.7O3-δ로 코팅된 one end-closed type Ba0.5Sr0.5Co0.8Fe0.2O3-δ 중공사막을 제조하였다. 산소투과실험은 대기 중 공기를 사용하였으며 진공펌프를 연결하여 투과된 산소 유량 및 순도를 측정하였다.