기체분리용 기능소재에 대한 세계적인 시장의 요구가 증가함에 따라 광범위한 연구개발이 진행되고 잇다. 본 연구는 둘 이상의 기체혼합물에서 높은 이산화탄소 포집성능을 목적으로 하는 복합막의 제조이다. Isocyanate와 SI-PEG, 소 량의 촉매를 사용하여 코팅액을 제조한 뒤 PAN지지체 위에 코팅하여 복합막을 제조하였다. SEM기기를 활용하여 복합막의 코팅층을 확인하였고 Bubble flowmeter를 사용하여 기체투과특성평가를 실시하였다. 기체복합막의 두께는 3 um 이하로 고른 분포를 보이며, 50 GPU의 이산화탄소 투과값과 질소에 대한 이산화탄소 선택도는 15의 결과를 보였다.

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.

In this study we manufacture a Ni-Cr-B-Si +WC/12Co composite coating layer on a Cu base material using a laser cladding (LC) process, and investigate the microstructural and mechanical properties of the LC coating and Ni electroplating layers (reference material). The initial powder used for the LC coating layer is a powder feedstock with an average particle size of 125 μm. To identify the microstructural and mechanical properties, OM, SEM, XRD, room and high temperature hardness, and wear tests are implemented. Microstructural observation of the initial powder and LC coating layer confirm the layer is composed mainly of γ-Ni phases and WC and Cr23C6 carbides. The measured hardness of the LC coating and Ni electroplating layers are 653 and 154 Hv, respectively. The hardness measurement from room up to high temperatures of 700°C result in a hardness decrease as the temperature increases, but the hardness of the LC coating layer is higher for all temperature conditions. Room temperature wear results show that the wear loss of the LC coating layer is 1/12 of the wear level of the Ni electroplating layer. The measured bond strength is also greater in the LC coating than the Ni electroplating.

Despite the importance of city parks and the changes in perception and involvement of users, park management budgets are constantly being contracted. Accordingly, the problems on maintenance control of neighborhood parks are now being realized, and studies on management improvement are required. This study is focused on the operation conditions and user satisfaction of the neighborhood parks in Daegu. Based on the analysis, efficient park management measures are suggested and baseline data are provided for subsequent studies. Targeting the neighborhood parks that the primary local government of Daegu is directly managing, the maintenance management costs were compared for a period of five years, and the average budget per unit area was calculated based on the completed neighborhood parks. Eight neighborhood parks were selected, including Dalseo-gu, whose average budget per unit area is the highest, and Buk-gu, where it is the lowest. Further, field and user attitude surveys were carried out. From the results of the field survey, the administrative status on neighborhood parks of Dalseo-gu and Buk-gu showed a satisfactory level, beyond the average one. The management score on neighborhood parks of Dalseo-gu appeared higher than that in Buk-gu. According to the results of the attitude survey, which targeted the users of these parks, the main users utilizing the neighborhood parks were nearby residents, and their share of responses indicating that they go to the park on foot was the highest, 74.6%. Regarding the importance and satisfaction on the elements that compose the parks, classified in 7 point-scaled criteria, the favorable answers were those over 5 points. According to the levels of user satisfaction calculated based on this method, Buk-gu ranked higher than Dalseo-gu. Based on the expected level of service and the evaluation of how they are perceived, through an IPA analysis, the park facilities were divided into to four areas. As a result, it emerged that continuous interest and intensive management of the properties would be required.

This study was conducted on the “traditional area” of Dunsan in Daejeon, and 22 apartment complexes in Doan new city in the “new urban area”. Its goal was to compare and analyze green percentage of each apartment complex’s exterior space. The application examples of the green percentage were examined. Through the advanced research, exterior space types of apartment housing were divided according to chronical change. Five kinds of space (entry space, main pedestrian space, auxiliary pedestrian space, building surroundings space, and playground space) were designated to enable comparison analyses between green-space percentages of the apartment complex in both the Dunsan and Doan areas. Five exterior spaces and 22 apartment complexes in the Dunsan area and in the Doan new urban area were photographed. This study serves as a basic exploratory study to derive the baseline Index of Greenness results of traditional area and new urban area, addressing the lack of such research on the residential facilities. The study also analyzed differences between the two greenness indexes with respect to shape and space. Compared with the average rates of index of greening in traditional areas and new urban areas, Doan (a new urban area) showed an Index of Greenness rate of 34.1%, and Dunsan (a traditional area) showed an Index of Greenness rate of 40.5%, which was 6.4% higher. It is considered that the shape of each green space, the arrangement of various facilities, and the design of the spaces have a great influence on the differences of the Index of Greenness.

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

Fe-6.5 wt.% Si alloys are widely known to have excellent soft magnetic properties such as high magnetic flux density, low coercivity, and low core loss at high frequency. In this work, disc-shaped preforms are prepared by spark plasma sintering at 1223 K after inert gas atomization of Fe-6.5 wt.% Si powders. Fe-6.5 wt.% Si sheets are rolled by a powder hot-rolling process without cracking, and their microstructure and soft magnetic properties are investigated. The microstructure and magnetic properties (saturation magnetization and core loss) of the hot-rolled Fe-6.5 wt.% Si sheets are examined by scanning electron microscopy, electron backscatter diffraction, vibration sample magnetometry, and AC B–H analysis. The Fe-6.5 wt.% Si sheet rolled at a total reduction ratio of 80% exhibits good soft magnetic properties such as a saturation magnetization of 1.74 T and core loss (W5/1000) of 30.7 W/kg. This result is caused by an increase in the electrical resistivity resulting from an increased particle boundary density and the oxide layers between the primary particle boundaries.

This study examines the construction and management of physical facilities in natural recreational forests that have been created after gaining an understanding of how visitors will use them. It also studies operations tailored for the use of visitors to natural recreation forests. The study presents basic data pertaining to management of natural recreation forests, analyzes the impact of current facilities on visitor satisfaction, and reveals the potential for new programs to be implemented. The independent variables in this study are facilities and program establishment/management and program utilization pertaining to the operation of natural recreation forests. The considered variables include facilities management and facilities requirements categorized by state programs. Program needs were analyzed using correlation. The state of facilities management in natural recreation forests, utilization program implementation, and demand for utilization programs were found to have a positive (+) influence on visitor satisfaction. The results of the rank regression analysis of the influence of the independent variables on visitor satisfaction decreases in the following order: state of facilities management, utilization program implementation, and demand for utilization programs. Visitors to natural recreation forests prefer recreational activities that provide a break from their normal routine, rather than the use of other aggressive utilization programs. Therefore, a higher priority should be given to ensuring appropriate provision of facilities that generate higher visitor satisfaction, as well as their stable management, compared to other utilization programs. Therefore, there are some indications that natural recreation forests of the future will benefit from the development and implementation of an essential set of utilization programs that will have a positive (+) impact on visitor satisfaction.

Fe-Si-Cr ferroalloy is predominantly produced by carbothermic reduction. In this study, silicothermic and carbothermic mixed reduction of chromite ore to produce Fe-Si-Cr alloy is suggested. As reductants, silicon and silicon carbide are evaluated by thermochemical calculations, which prove that silicon carbide can be applied as a raw material. Considering the critical temperature of the change from the carbide to the metallic form of chromium, thereduction experiments were carried out. In these high temperature reactions, silicon and silicon carbide act as effective reductants to produce Fe-Si-Cr ferroalloy. However, at temperatures lower than the critical temperature, silicon carbide shows a slow reaction rate for reducing chromite ore. For the proper implementation of a commercial process that uses silicon carbide reductants, the operation temperature should be kept above the critical temperature. Using equilibrium calculations for chromite ore reduction with silicon and silicon carbide, the compositions of reacted metal and slag were successfully predicted. Therefore, the mass balance of the silicothermic and carbothermic mixed reduction of chromite ore can be proposed based on the calculations and the experimental results.

분리막을 이용한 기체 투과 특성은 이산화탄소 분리성능이 탁월하다. 복합막제조에 앞서 Si-PEG를 합성한 뒤, 1H-NMR, GPC, FT-IR등을 이용하여 합성을 확인하고 지지체 위에 실리콘 코팅을 하여 SEM 사진으로 복합막의 코팅층 확인 및 Bubble flowmeter을 이용하여 기체투과 성능을 측정하였다. 코팅제는 Isocyanate와 합성한 Si-PEG, 소량의 촉매를 사용하여 지지체 위에 코팅하였고 고온에서 가교과정을 거친 후 복합막을 제조하였다. 제조한 기체투과 복합막은 3um 이하로 고른 분포를 보이고, 50GPU의 이산화탄소 투과값과 질소에 대한 이산화탄소 선택도는 15의 결과를 보였다. 또한 코팅제의 조성을 다양하게 변화하여 각각의 (N2, O2, CO2) 투과 성능을 확인 하였다.

In-cylinder flows in a motored 3.5L four-valve SI engine are investigated quantitatively using three-dimensional LDV system to determine how intake system affects the flow field. For this study, the same engine head, cylinder, and piston are used. The purpose of this work is to develop quantitative methods which correlate in-cylinder flows to engine performance. The LDV results reveal that collision regions and zones around vortices can be traced as the origins of turbulent kinetic energy. High levels of turbulent kinetic energy are found in regions of high shear flow, attributed to the collisions of intake flows. These specific results support the more general conclusion that the inlet conditions play the dominant role in the generation of the turbulence fields during the intake stroke.

This study establishes a landscape plan and landscape-related income generation project plan based on the Weonsaekjang village in Jeonju-si by applying location characteristics and tangible and intangible village assets to enhance the quality of living environment of local residents as well as the competitiveness of this village as a focal village for rural tourism. Planning was carried out in the order of theoretical consideration, village resource investigation and analysis, basic design, and detailed project planning. This study is significant for the following reasons. First, it has formed an appealing image of this village as a place for rural tourism by applying differentiated village assets as the theme of landscape plan. Secondly, a village for rural tourism in which residents can constantly live has been developed as infrastructure for tourism and is based on the residential environment. Moreover, a landscape plan that enables visitors to experience activities that stimulate their senses has been established to promote tourism that boosts consumption. Further, landscape elements that used to hamper the village landscape were enhanced as landmarks to create unique tourism resources. In addition, the effects of landscape plan were maximized through a flexible approach that encourages the linkage between this village and adjacent tourist attractions. Finally, the participation of residents in the project was promoted from the stage of planning to ensure driving force for the project implementation and maintenance.

The BCBJ (Back Contact and Back Junction) or back-lit solar cell design eliminates shading loss by placing the pn junction and metal electrode contacts all on one side that faces away from the sun. However, as the electron-hole generation sites now are located very far from the pn junction, loss by minority-carrier recombination can be a significant issue. Utilizing Medici, a 2-dimensional semiconductor device simulation tool, the interdependency between the substrate thickness and the minority-carrier recombination lifetime was studied in terms of how these factors affect the solar cell power output. Qualitatively speaking, the results indicate that a very high quality substrate with a long recombination lifetime is needed to maintain the maximum power generation. The quantitative value of the recombination lifetime of minority-carriers, i.e., electrons in p-type substrates, required in the BCBJ cell is about one order of magnitude longer than that in the front-lit cell, i.e., 5 × 10−4 sec vs. 5 × 10−5 sec. Regardless of substrate thickness up to 150 μm, the power output in the BCBJ cell stays at nearly the maximum value of about 1.8 × 10−2 W·cm−2, or 18 mW·cm−2, as long as the recombination lifetime is 5 × 10−4 s or longer. The output power, however, declines steeply to as low as 10 mW·cm−2 when the recombination lifetime becomes significantly shorter than 5 × 10−4 sec. Substrate thinning is found to be not as effective as in the front-lit case in stemming the decline in the output power. In view of these results, for BCBJ applications, the substrate needs to be only mono-crystalline Si of very high quality. This bars the use of poly-crystalline Si, which is gaining wider acceptance in standard front-lit solar cells.

The purpose of the present study is to figure out what the issues faced by architecture were at the time immediately before the transition to modern era centering of the works of Otto Wagner who acted in Vienna, Austria at the Fin de siècle. Therefore, the following points were examined in the present study; first, how were new spaces necessary to accommodate modern lives organized and how were the plans changed; second, how did the external expressions of architecture pursued by Otto Wagner appeared between arts and technologies, between historicism and modernity, and between decorations and functions. Through the study, it could be seen that Wagner began from historicism and traditionalism and tried to compromise them with modernity. Many modern characteristics appeared a priori in Wagner’s works from the construction of ‘Linke Wien Zeile housing block’ in 1898, his works completely broke from the typical historicism styles to open the period of inventive ‘Secession styles.’ At that time, Wagner concentrated on so called ‘flat decorations.’ Thereafter, his residential architecture completed to modern styles with ‘Neustiftgasse housing block’ as the peak. The characteristics of modern housing as above became a cornerstone of the modern functionalism later.

Silicon alloys are considered promising anode active materials to replace Li-ion batteries by graphite powder, because they have a relatively high capacity of up to 4200 mAh/g, and are environmentally friendly and inexpensive ECO-materials. However, its poor charge/discharge properties, induced by cracking during cycles, constitute their most serious problem as anode electrode. In order to solve these problems, Si-Ge-Al alloys with porous structure are designed as anode alloy powders, to improve cycling stability. The alloys are melt-spun to obtain the rapidly solidified ribbons, and then ball-milled to make fine powders. The powders are etched using 1 M HCl solution, which gives the powders a porous structure by removing the element Al. Subsequently, in this study, the microstructures and the characteristics of the etched powders are evaluated for application as anode materials. As a result, the etched porous powder shows better electrochemical properties than as-milled Si-Ge-Al powder.

Cobalt was electrodeposited onto chemical vapor deposition (CVD) graphene/Si/SiO2 substrates, during different time intervals, using an electrolyte solution containing a low concentration of cobalt sulfate. The intention was to investigate the details of the deposition process (and the dissolution process) and the resulting magnetic properties of the Co deposits on graphene. During and after electrodeposition, in-situ magnetic measurements were performed using an (AGFM). These were followed by ex situ morphological analysis of the samples with ΔtDEP 30 and 100 s by atomic force microscopy in the non-contact mode on pristine CVD graphene/SiO2/Si. We demonstrate that it is possible to electrodeposit Co onto graphene, and that in-situ magnetic measurements can also help in understanding details of the deposition process itself. The results show that the Co deposits are ferromagnetic with decreasing coercivity (HC) and demonstrate increasing magnetization on saturation (MSAT) and electric signal proportional to remanence (Mr), as a function of the amount of the electrodeposited Co. It was also found that, after the end of the dissolution process, a certain amount of cobalt remains on the graphene in oxide form (this was confirmed by X-ray photoelectron spectroscopy), as suggested by the magnetic measurements. This oxide tends to exhibit a limited asymptotic amount when cycling through the deposition/dissolution process for increasing deposition times, possibly indicating that the oxidation process is similar to the graphene surface chemistry.

In this study, we used I-V spectroscopy, photoconductivity (PC) yield and internal photoemission (IPE) yield using IPE spectroscopy to characterize the Schottky barrier heights (SBH) at insulator-semiconductor interfaces of Pt/HfO2/p-type Si metal-insulator-semiconductor (MIS) capacitors. The leakage current characteristics of the MIS capacitor were analyzed according to the J-V and C-V curves. The leakage current behavior of the capacitors, which depends on the applied electric field, can be described using the Poole-Frenkel (P-F) emission, trap assisted tunneling (TAT), and direct tunneling (DT) models. The leakage current transport mechanism is controlled by the trap level energy depth of HfO2. In order to further study the SBH and the electronic tunneling mechanism, the internal photoemission (IPE) yield was measured and analyzed. We obtained the SBH values of the Pt/HfO2/p-type Si for use in Fowler plots in the square and cubic root IPE yield spectra curves. At the Pt/HfO2/p-type Si interface, the SBH difference, which depends on the electrical potential, is related to (1) the work function (WF) difference and between the Pt and p-type Si and (2) the sub-gap defect state features (density and energy) in the given dielectric.