• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.547-551
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• 2010

In this paper, Double rectangular patch with 4-bridges is investigated for solution of IEEE 802.11b/g(2.4GHz) and 802.11a(5.7GHz). Rectangular patch for 5.7GHz frequency band is printed on the PCB substrate and connected to another rectangular patch for 2.4GHz frequency band with 4-bridges to obtain dual band operation in a antenna element. The proposed antenna has a low profile and is fed by $50{\Omega}$ coaxial line. The dielectric constant of the designed antenna substrate is 3.27. Two rectangular patches have each resonance frequencies that are 2.4GHz and 5.7GHz. A dual-band characteristic is shown as connecting two rectangular patch using four bridges. Also, the proposed antenna is shown input return loss that is below -10dB at 2.4GHz and 5.7GHz of WLAN(Wireless LAN).

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.56-62
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• 2013

We present a rectifier for wireless power transmission using multiplier configuration in layout for MOSFETs which works at 13.56 MHz, designed to fit in CMOS process where conventionally used diodes are replaced with the cross-coupled MOSFETs. Full bridge rectifier structure without comparators is employed to reduce current consumption and to be working up to higher frequency. Multiplier configuration designed in layout reduces time delay originated from parasitic series resistance and shunt capacitance at each finger due to long connecting layout, leading to fast transition from on-state to off-state cross-coupled circuit structure and vice versa. The power conversion efficiency is significantly increased due to this fast transition time. The rectifier is fabricated in $0.11{\mu}m$ CMOS process, RF to DC power conversion efficiency is measured as 86.4% at the peak, and this good efficiency is maintained up to 600 MHz, which is, to our best knowledge, the highest frequency based on cross-coupled configuration.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.61-68
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• 2004

Recently, a fuel cell is remarkable for new generation system. The fuel cell is characterized by low voltage and high current. Therefor, for connecting to general load, it needs both a step up converter and an inverter. The proposed system consists of an isolated DC-DC converter to boost the fuel cell voltage to 380[Vdc] and a PWM inverter with LC filter to convert the dc voltage to single phase 220[Vac]. Also, bi-directional DC-DC converter for fuel cell generation system is composed to improve load response characteristic. In this paper, full bridge converter and the single phase inverter are designed and installed for fuel cell. Simulation and experiment verify that fuel cell generation system could be applied for the distributed generation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.54-60
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• 2008

The bus architecture consists of a master initiating a communication transaction, a slave responding to the transaction, a arbiter selecting a master, a bridge connecting buses and so on. Recently this is more complicated and developed toward multi-bus architecture. In this paper, several cases of multi-shared bus architecture are discussed and in order to decrease the bridge latency, the architecture introducing a memory selector is proposed. Finally, a LCD controller using DMA master is integrated in this bus architecture that is verified due to RTL simulation and FPGA board test. DMA, LCD line buffer and SDRAM controller are normally operated in the timing simulation using ModelSim tool, and the LCD image is confirmed in the real FPGA board containing LCD panel.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.2
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• pp.297-305
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• 2016

This study aims to analyze characteristics of environmental load for the construction phase of PSC beam bridge based on Life Cycle Assessment. For detail computation of environmental load, the construction materials and energy consumption are derived from the BOQ, also connecting with environmental load by Korea LCI Database Information Network. The characteristic of environmental impact was analyzed by 25 cases and cut-off ratio was 80% to 94%. The result sorted by construction materials revealed that environmental load were 53.3% for ready-mixed concrete, 9.6% for wire rod, 7.8% for rebar, 6.8% for cement, 5.5% for plywood, and 5.2% for energy. Furthermore, the result of environmental impact revealed that 45.5% for global warming, 30.4% for abiotic resources depletion, 10.5% for human toxicity, and 8.9% for photochemical oxidant creation. In the future, we can make a decision considering environmental load based on LCA at design phase.

• Journal of the Korean Society of Safety
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• v.34 no.2
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• pp.40-47
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• 2019

The Half-depth precast deck is a structural system that utilizes pre-cast panels pre-built at the factory as formwork at the construction stage and as a major structural member at the same time after completion. These systems have joints between segments, and the detail and performance of the joints are factors that have a very large impact on the quality, such as the constructability and durability of the bridge decks. In this study, strength performance evaluation was performed for improved joints using connecting rebar by experimental method. Static loading tests were conducted on the test specimen with improved joint, those with existing joint and those without joint. The test results of the specimens were compared to each other, and the flexural strength required by the design was compared. The flexural strength required in the design was presented by finite element analysis. It has been shown that the flexural strength of the specimens with joints were more than twice that required by the design. But the flexural strength of the specimen with existing joint was about 84% of that without joint. The flexural strength of the specimen with improved joints was a nearly similar degree of that compared to the specimen without joint. And a comparison of the moment-deflection relationship curves of the two specimens also shows a very similar flexural behavior. It is confirmed that improved joint has sufficient flexural strength. In addition to strength, the bridge decks require serviceability, such as deflection and cracking, and in particular, fatigue resistance due to repetitive live loads is an important performance factor. Therefore, further verification studies are required.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.35-43
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• 2020

Currently, cofferdams of circular cross section are widely applied as temporary facilities for the installation of bridge foundations in river/sea bridge construction in Korea. Existing caisson, sheet pile, and cell type cofferdam are widely used, but these methods take a lot of time and cost for installation and dismantling. In the case of the existing sheet pile construction method, attention is needed to secure internal and external stability because of the damage to the sheet pile due to ground penetration and difficulty in connecting element members. In this study, penetration design of circular steel pipes using suction pressure was performed on the soft ground of the west coast, and it was confirmed that penetration construction using suction pressure was possible through field tests. It was confirmed that applying the ground analysis results using the cone penetration test (CPT) to the design rather than the standard penetration test (N value) results more similar to the field test results. In addition, it was confirmed that local failure of the inside of the cofferdam was induced when a suction pressure higher than the upper limit suction pressure was applied in the silty sand.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1542-1549
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• 2011

The Transitional zone between bridge abutment and earthwork is one of the representative vulnerable zones in railway where differential settlements may take place due to the different supportive stiffness. Although transitional zones are managed with stricter standards than those of the other earthwork zones either in the design and construction stages, it is very difficult to prevent differential settlement perfectly. A three-dimensional numerical analyses were performed by applying train moving load in this study. The analytical model including abutments and earthwork zones was constituted with rail, sleepers, track concrete layer (TCL), hydraulic stabilized base (HSB), reinforced road bed, and road bed using railway and road base structure. The clamp connecting the rail and sleeper were also modeled as the element with spring coefficient. The train wheel is modeled in the actual size and moved on the rail with 300 km/hr speed. The deformation characteristics at each point of the rail and the ground were considered in detail when moving the train wheel. The analysis results were compared with those from the two-dimensional analysis without considering moving load. The research results show that displacement and stress were greater in the three-dimensional analysis than in other analyses, and the three-dimensional analysis with moving load should be performed to evaluate railway performance.

• Geomechanics and Engineering
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• v.2 no.2
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• pp.125-140
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• 2010

Slope stability analysis of the right abutment of a railway bridge proposed at about 350 m above the ground level, crossing a river and connecting two huge hillocks in the Himalayas, India is presented in this paper. The site is located in a highly active seismic zone. The rock slopes are intensely jointed and the joint spacing and orientation are varying at different locations. Static slope stability of the rock slope is studied using equivalent continuum approach through the most commonly used commercial numerical tools like FLAC and SLOPE/W of GEOSTUDIO. The factor of safety for the slope under static conditions was 1.88 and it was reduced by 46% with the application of earthquake loads in pseudo-static analysis. The results obtained from the slope stability analyses confirmed the global stability of the slope. However, it is very likely that there could be possibility of wedge failures at some of the pier locations. This paper also presents the results from kinematics of right abutment slope for the wedge failure analysis based on stereographic projections. Based on the kinematics, it is recommended to flatten the slope from 50o to 43o to avoid wedge failures at all pier locations.

• BMB Reports
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• v.40 no.2
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• pp.261-269
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• 2007

The structure and dynamics of a 37-residue antimicrobial peptide gaegurin 4 (GGN4) isolated from the skin of the native Korean frog, Rana rugosa, was determined in SDS micelles by NMR spectroscopy. The solution structure of the peptide in SDS micelles was determined from 352 NOE-derived distance constraints and 22 backbone torsion angle constraints. Dynamic properties for the amide backbone were characterized by $^1H-^{15}N $heteronuclear NOE experiments. The structural study revealed two amphipathic helices spanning residues 2-10 and 16-32 and that the helices were connected by a flexible loop. An intraresidue disulfide bridge was formed between residues Cys31 and Cys37 near the C-terminus. The loop region (11-15) connecting the two helices are were slightly more flexible than these helices themselves. From the fact that since there is no contact NOEs between two helices, it is implied that the GGN4 peptide shows an independent motion of both helices which has an angle of about $ 60^{\circ}-120^{\circ}$ from each other.