• Progress in Superconductivity
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• v.10 no.2
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• pp.99-102
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• 2009

We report our development of the fabrication process of sub-micron scale $Al-AlO_x-Al$ tunnel junction by using electron-beam lithography and double-angle shadow evaporation technique. We used double-layer resist to construct a suspended bridge structure, and double-angle electron-beam evaporation to form a sub-micron scale overlapped junction. We adopted an e-beam insensitive resist as a bottom sacrificing layer. Tunnel barrier was formed by oxidation of the bottom aluminum layer between the bottom and top electrode deposition, which was done in a separate load-lock chamber. The junction resistance is designed and controlled to be 50 $\Omega$ to match the impedance of the transmission line. The junctions will be used in the broadband shot noise thermometry experiment, which will serve as a link between the electrical unit and the thermodynamic unit.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.33-44
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• 2007

Prohibition of lane changes in bridges and tunnels have been many problems in throughputs of expressways caused by heavy vehicles and slow-moving traffics. Nevertheless, those are constructed actively by the general trends, which are preservation of environment and ecosystem are more important, because mountainous districts are about 70% across the whole extent of Korea. In this paper, the proper design standards for permission of lane changes in bridges and tunnels classified into structure, safe, and driver's conveniences are suggested as follows. 1. Right shoulder should have more than 2.5m in bridges and tunnels. 2. Sufficient equipments of guidance like as directional signs, fingerposts, variable message signs, and markings should be established to smooth and safe lane changes of drivers. 3. Snow melting systems should be established in bridges worried about freezing. 4. Tunnels must be not only satisfied standards for prevention of disasters (2004.11) and lighting rules (KSA 3703), but also established anti-freezing facilities in entrance and exit. 5. The drivers should have honed on their car lights.

• Computational Structural Engineering
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• v.10 no.3
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• pp.157-165
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• 1997

This research aims to develop an algorithm of optimal transducer placement for health monitoring of large structural system. The structural vibration response-based health monitoring is considered one of the best for the system which requires a long-term, continuous monitoring. In its experimental modal testing, however, it is difficult to decide on the measurement locations and their number, especially for complex structures, which have a major influence on the quality of the results. In order to minimize the number of sensing operations and optimize the transducer location while maximizing the accuracy of results, this paper discusses about an optimum transducer placement criterion suitable for the identification of structural damage for continuous health monitoring. As a criterion algorithm, it proposes the Kinetic Energy Optimization Technique (EOT), and then addresses the numerical issues which are subsequently applicable to actual experiment where a bridge model is used. By using the experimental data, it compares the EOT with the EIM(Effective Indefence Method) which is generally used to optimize the transducer placement for the damage identification and control purposes. The comparison conclusively shows that the EOT algorithm proposed in this paper is preferable when a structure is to be instrumented with fewer sensors for monitoring purpose.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.3
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• pp.209-218
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• 2016

Recently, Wind-turbine electronic generator become popular. Wind-Turbine is free to cost for purchase and noise problem. For this reason, trend is shifting from Wind-turbine on land to offshore. Research and Development for offshore Wind-turbine has been conducted by various research institution. However, There is no solid design code for offshore Wind-turbine even in domestic as well as foreign. In this paper, conduct seismic analysis and compare results using design codes Korea Bridge Design Codes, Korea Harbor and Marina Design Codes, and DNV OS. Time-History analysis conducted for checking time dependent effect. The Added-Mass Method applied to consider water-structure effects and compared for w/ water and w/o water condition.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.405-410
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• 2005

In these days, the piezoresistive material has been applied to various sensors in order to measure the change of physical quantities. But the relationship between the sensitivity of a sensor and the position and size of piezoresistor has rarely been studied. Therefore, this paper was focused on the distribution of the resistance change ratio on the diaphragm and bridge surface where piezoresistor would be formed, and proposed the proper size and position of piezoresistor with which the sensitivity of sensor was increased. As the width of mass and boss was increased, the distance between piezoresistors was closed and the maximum value of resistance change ratio was decreased by the increase of the structure stiffness.

• Journal of KIBIM
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• v.5 no.3
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• pp.33-40
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• 2015

Over a few decades, off-site construction (OSC) has been widely used for building and bridge constructions. OSC is a construction method that build structures at a different location than the location of use, and normally it occurs in a manufacturing plant. There are many studies on the perceived benefits of OSC, yet relatively few studies which quantitatively assess the benefits and factors affecting the decision of the use of OSC have been investigated. This study investigates the influencing factors of the use of OSC system and its revitalization solutions in the construction industry. As the research method, interview and questionnaire survey are conducted by visiting industry experts of OSC and sending a questionnaire to the OSC stakeholders including engineers, manufacturers, contractors and clients in the United Kingdom (UK). The construction industry of the UK is targeted for the study since it has a number of commons with the Korean construction industry in terms of the structure of the construction industry and current low take-up of the OSC. The survey provides the results that the reluctance of clients to use OSC is the key factor of the slow use of OSC despite of the perceived benefits of OSC. In addition, in order to revitalize OSC in the construction market, three revival recommendations are suggested based on the survey results.

• Smart Structures and Systems
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• v.20 no.2
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• pp.127-137
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• 2017

Identification of damping characteristics is of significant importance for dynamic response analysis and condition assessment of structural systems. Damping is associated with the behavior of the energy dissipation mechanism. Identification of damping ratios based on the sensitivity of dynamic responses and the model updating technique is investigated with numerical and experimental investigations. The effectiveness and performance of using the sensitivity-based model updating method and vibration monitoring data for damping ratios identification are investigated. Numerical studies on a three-dimensional truss bridge model are conducted to verify the effectiveness of the proposed approach. Measurement noise effect and the initial finite element modelling errors are considered. The results demonstrate that the damping ratio identification with the proposed approach is not sensitive to the noise effect but could be affected significantly by the modelling errors. Experimental studies on a steel planar frame structure are conducted. The robustness and performance of the proposed damping identification approach are investigated with real measured vibration data. The results demonstrate that the proposed approach has a decent and reliable performance to identify the damping ratios.

• Architectural research
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• v.16 no.3
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• pp.109-120
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• 2014

South and North Korea, the divided nations on the Korean peninsula, began with the same modern city planning system, but following the adoption of different national ideologies-capitalism and socialism-, they established their own city planning system and developed their cities accordingly. However, the process of planning and developing a joint city of Kaesong Industrial Complex (KIC) led to the recognition about the need to bridge the differences and prepare for future joint development. This study examines North Korea's city planning system by comparing the two Koreas' systems, and identify the characteristics of North Korea's city planning system through a case analysis of the KIC. By comparing two cases, we found two distinct characteristics of North Korea's. The one is a tool for realizing ideologies and maintaining national system. The other one is that it is ideology-oriented system for the supreme leader and party while South Korea has control-oriented system for the public. We analyze the KIC case based on four pillars: planning system, development system and procedure, master plan, and use behaviors. Result of analysis shows that in KIC there are many socialistic features as we mentioned above in terms of planning system, urban design & structure, and use behavior even though a private enterprise-Hyundai Asan, in South Korea led the whole process. This study is meaningful in that it identifies the specific characteristics of North Korea's city planning focusing on the KIC and is expected to serve as a baseline material to set the future direction for North Korea's development.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2279-2285
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• 2011

The geometries, electronic structures and absorption spectra of the two organic triphenylamine-based dyes TA-St-CA and TA-DM-CA, containing identical electron donors and acceptors but the different conjugated bridges, were studied by density functional theory (DFT) at the B3LYP and PBE1PBE levels, respectively. The influence of para-orientating methoxyl units on the electronic structures and light absorption properties of the dyes and the consequent photovoltaic performance of the dye-sensitized solar cells (DSSCs) were investigated in detail. The results indicate that the introduction of the para-orientating methoxyl units into the conjugated bridge induces the increased absorption wavelength as well as the more negative EHOMO corresponding to the bigger driving force $(E_{I^-/I^-_3}-E_{HOMO})$ for dye reduction, which together improve the photovoltaic performance of TA-DM-CA, although there is a decline of the open circuit voltage caused by the more negative $E_{LUMO}$.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2487-2493
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• 2014

Dimeric ${\beta}$-cyclodextrin linked by a thioether bridge was synthesized from a reaction of mono-6-iodo-6-deoxy-${\beta}$-cyclodextrin with sodium sulfide, and the structure was analyzed using nuclear magnetic resonance spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The effects of thioether-bridged dimeric ${\beta}$-CD on the aqueous solubility of flavonols (myricetin, quercetin, and kaempferol) were investigated by ultraviolet-visible spectroscopy. The aqueous solubility of myricetin, quercetin, and kaempferol were enhanced 33.6-, 12.4-, and 10.5-fold following the addition of 9 mM of thioether-bridged dimeric ${\beta}$-CD. In comparison, the aqueous solubility of myricetin, quercetin, and kaempferol were enhanced 5.4-, 3.3-, and 2.7-fold using the same concentration of monomeric ${\beta}$-cyclodextrin. Furthermore, the formation of flavonol/thioether-bridged dimeric ${\beta}$-CD inclusion complexes was confirmed with nuclear magnetic resonance, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. The results showed that the nature of the complexes significantly differed from that of free flavonols. Herein, we suggest that the thioether-bridged dimeric ${\beta}$-CD can act as an effective complexing agent for flavonols.