• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.102-108
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• 2013

In manufacturing of solution-processed organic electronic devices, a spin coating method is frequently used, but which has a big problem. Solvent in a solution has a decisive effect such as physical and chemical damage for successive solution-based film deposition. Such a severe damage by solvent restricts for fabricating building blocks of multi-layered films from solutions. In this work, it will be shown that a proper combination of well-known solvents gives a chance to fabricate multi-layered film, also this new method was applied to make organic field effect transistor. Two types of bottom gate, bottom contact transistors were fabricated, one of which is fabricated by conventional single spin coating method, the other fabricated by double spin coating method. Compared with the electrical characteristics in a single spin coated transistor, the leakage current between source and gate electrode was decreased, ON state current was increased, and the extracted saturation mobility was multiplied more than 2.7 time for double spin coated transistors. It is suggested that the multiple coated gate dielectric structure is more desirable for high performance organic ferroelectric field effect transistors.

• Journal of Korean Society of Steel Construction
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• v.28 no.6
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• pp.439-448
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• 2016

Extended end-plate connections(EEPC) are a type of connection applied in Pre-Engineered Building structures comprising beam-column connections of steel structures or tapered members. Extended end-plate connections(EEPC) show different behavioral characteristics owing to the influence of plate thickness, gauge distance of high strength bolt, diameter of high strength bolt frame, and the number of high strength bolts. In the USA and Europe, extended end-plate connections(EEPC) are applied in beam-column connections of steel structures in various forms; however, these are not widely applied in structures in Korea.This can be attributed to the fact that the proposal of design strength types for extended end-plate connections(EEPC), proposal of connection specifications, evaluation of seismic performance, and are not being performed appropriately. Therefore, the purpose of this study is to provide basic data for the domestic application of Unstiffened extended endplate connections. To realize this, nonlinear finite element analysis was conducted on a 12-mm thick Unstiffened extended endplate connections.

• Journal of the Korean Geographical Society
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• v.45 no.1
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• pp.144-164
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• 2010

This study aims to reveal path selection strategies and individual differences in a navigation task. Two experiments were presented that studied human route planning performance as well as the cognitive strategies and processes involved. For the outdoor task, university students were asked to select a route based on the instruction, i.e. to find the best route from the campus main gate to the Education Building for conference visitors by locating eight signposts. Results indicate (1) that locations of signposts were selected preferably at decision points where the traveler needs to make a choice and starting/ending points of the navigation task and (2) a variety of route planning strategies considering efficiency goal (e.g., the shortest path), environmental characteristics (e.g., fewest turns), and aesthetic purpose (e.g., most scenic) were used. It is notable that some participants took into account more than one path by locating one or two signposts on an alternative route while others preferred a linear route connecting signposts between the start point and the destination. Prior to the main experiment, the same participants were asked to complete the same task inside the classroom to investigate changes in strategies between two tasks. Participants often tend to place signposts at more regular intervals for the indoor navigation task than the same task conducted outside.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.595-602
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• 2006

An experimental study was conducted to investigate seismic behaviour of post-tensioned(PT) exterior slab-column connections used for the purpose to resist gravity loads only. For these, 2/3-scale, two PT post-tensioned exterior connections with two different tendon arrangement patterns and one conventional reinforced concrete(RC) exterior connection was tested under quasi-static, uni-directional reversed cyclic loading. During the lateral testing, gravity forces transferred to the column were kept constant to closely simulate a moment to shear ratio of a real building. One of the objectives of this study was to assess the necessity and/or the quantity of bottom bonded reinforcement needed to resist moment reversal which would occur under significant inelastic deformations of the adjacent lateral force resisting systems. The ACI 318 and 352 provisions for structural integrity were applied to provide the bottom reinforcement passing through the column for the specimens. Prior test results were also collected to conduct comparative studies for some design parameters such as the tendon arrangement pattern, the effect of post-tensioning forces and the use of bottom bonded reinforcement. Consequently, the impact of tendon arrangement on the seismic performance of the PT connection, that is lateral drift capacity and ductility, dissipated energy and failure mechanism, was considerable. Moreover, test results showed that the amount of bottom reinforcement specified by ACI 352. 1R-89 was sufficient for resisting positive moments arising from moment reversal under reversed cyclic loads. Shear strength of the tested specimens was more accurately predicted by the shear strength equation(ACI 318) considering the average compressive stress over the concrete($f_{pc}$) due to post-tensioning forces than that without considering $f_{pc}$.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.333-336
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• 2008

As the high-rise building increase due to the gravitation of population to big cities recently, it requires high quality and high performance of Concrete. As a result, people are keenly interested in Meta-kaolin as new admixture favorable from an economic perspective, which has strength and endurance with admixture at the same level like Silicafume. Accordingly, as to Meta-kaolin, this study was to set by three levels like domestic one, foreign one, and Silicafume, the waterbinding material ratio 25%, and four level substitute like 0, 10, 20, and 30(%) in order to compare and analyze the quality characteristics of high-strength concrete according to the substitute of Meta-kaolin applicable with replacement of Silicafume. As a result of performing experiment, as to the higher the additive amount of Superplasticizing agents in order to secure target liquidity was, the more the substitute in each admixture increased. This study had a tendency that the Silicafume increased the additive amount of Superplasticizing agents with high fineness compared with Meta-kaolin. In addition, the higher the substitute in each admixture was, the more its strength increased On the strength property, the higher the substitute in each admixture was, the more its strength increased. This study has found out that the Meta-kaolin has shown the better strength than the one of Silicafume. On the other hand, the relationship between the Compressive strength and Elastic coefficient has shown the similar formula suggested from ACI363.

• Korean Journal of Construction Engineering and Management
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• v.6 no.4 s.26
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• pp.101-112
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• 2005

Recently, a curtain wall construction is a exterior finishing components which is most used for shortening time in high-rise building as well as the class of key management factors in cost and schedule control. Also, it is recognized that an effective management for curtain wall process is a major subject to accomplish the project successfully. However, as the current management for curtain wall construction is focused on the construction stage, it makes problems such as errors in business performance, rework by mistakes and duplications, errors and omissions by ineffective information management and there has never been any efficient management from a view of the entire Curtain Wall Life-cycle process. Therefore, the aim of this study is to suggest a stage check point for process improvement in the curtain wall Life-cycle process through current curtain wall process analysis, and then to investigate the cause of waste factors using the Muda method from the Toyota Production System and extract the weighted effects of the waste factors using the analytical hierarchy process method. According to the result, Most of the inefficient factors happened in architectural design stage of the entire curtain wall Life-cycle process and my research identified that detail factors of them are a delay of decision making and an approval in changes, a deficit of engineering capacity and a delay of approval in architectural design drawings by owner, etc.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.912-921
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• 2005

Optical burst switching(OBS) is a promising solution for building terabit optical routers and realizing If over WDM. Channel scheduling Algorithm for reduce contention is one of the major challenges in OBS. We address the issue of how to provide basic burst channel scheduling in optical burst switched WDM networks with fiber delay lines(FDLs). In OBS networks the control and payload components or a burst are sent separately with a time gap. If CHP arrives to burst switch node, because using scheduling algorithm for data burst, reservation resources such as wavelength and transmit data burst without O/E/O conversion, because contention and void between burst are happened at channel scheduling process for data burst that happened the link utilization and bust drop probability Existent proposed methods are become much research to solve these problems. Propose channel scheduling algorithm that use Release Time of bust to emphasize clearance between data and data dissipation that is happened in data assignment in this treatise and maximize bust drop probability and the resources use rate (RTUC : Release Time Unscheduled Channel). As simulation results, Confirmed that is more superior in terms of data drop and link utilization than scheduling algorithm that is proposed existing. As simulation results, confirmed improved performance than scheduling algorithm that is proposed existing in terms of survival of burst, efficiency resource and delay. However, In case load were less, degradation confirmed than existent scheduling algorithm relatively, and confirmed that is superior in data drop aspect in case of load increased.

• Journal of the Korea Concrete Institute
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• v.17 no.3 s.87
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• pp.393-400
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• 2005

Steel encased composite columns have been used for buildings and piers of bridges. Since the column section for the pier is relatively larger than that of building columns, economical steel ratio needs to be investigated for the required performance. Composite action between concrete and embedded steel sections can be obtained by bond and friction. However, the behavior of the column depends on the load introduction mechanism. Compression can be applied to concrete section, steel section and composite section. In this paper, experiments on shear strength of the steel encased composite column were performed to study the effect of confinement by transverse reinforcements, mechanical interlock by holes, and shear connectors. Bond strength obtained from the tests showed considerably higher value than the design value. Confinement, mechanical interlock and stud connectors Increased the shear strength and these values can be used effectively to obtain composite action of Steel Reinforced Concrete(SRC) columns.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.39-40
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• 2010

The demands for longer span and reduction of story height have greatly increased as building structures become much larger and higher in recent years. Although the development of flexural members for reducing story height or making long span has been studied by many researchers and engineers, there is still a lack of efficient systems that meet these two demands simultaneously. This study aimed at developing a new composite beam system suitable for long span and reduction of story height, and proposed a prestressed composite beam with corrugated web. It has great resistance against non-symmetric construction load due to its strong out-of-plane shear strength with relatively small member height as well as good constructability and economic efficiency by removing/minimizing form work. The corrugated webs also make accordion effect introducing larger effective prestressing force to top and bottom flanges, which causes larger upward camber reducing the member deflection. Five full-scale specimens with key test parameters, which are web sectional shapes and number of drape points, were tested to understand their flexural behavior and to verify the performance of the proposed method. The experimental test results showed that the proposed prestressed composite beam had greater flexural strength and stiffness than the ordinary non-prestressed composite beam.

• Journal of the Korea Concrete Institute
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• v.27 no.3
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• pp.215-227
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• 2015

In this study, twenty four steel-fiber reinforced concrete (SFRC) beams using recycled coarse aggregates (RCA) were manufactured to examine the shear behavior of SFRC and to determine the beams' ultimate shear strengths. The RCA replacement ratio was fixed at 30%. The variables studied in this investigation are: (1) shear span-to-depth ratios (a/d) of 2, 3 and 4; (2) longitudinal reinforcement ratio (${\rho}$) of 0.008 and 0.0127; and (3) steel fiber volume fractions ($V_f$) of 0, 0.5, 0.75 and 1%. Test results were analyzed and then compared with the findings and proposals of various other researchers. Based on the test results, the more steel fiber volume fraction is increased, the large crack resistance and shear strength are exhibited. Most of the experimental data is higher than the theoretical value. Therefore, steel-fiber reinforced concrete beams using recycled coarse aggregates are suggested to be applied for building structures.