• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.2
• /
• pp.119-126
• /
• 2008

In this paper, the loop coupling model for the analysis of end launcher rectangular waveguide adapter are proposed. The formula of input impedance from this model are presented. The influence of propagation mode and higher modes in rectangular waveguide are analyzed and design parameters of the end launcher adapter are investigated. The computational results between the proposed theoretical analysis and the previous papers are compared and are verified by HFSS. The end launcher rectangular waveguide adapter consists of the coupling geometry which is connected the inner conductor of $50{\Omega}$ coaxial line through into the 17.6mm feeding loop in a WR90 commercial waveguide, and the VSWR is maximum 2.0 over operating frequency from 7.5GHz to 10.6GHz.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.1
• /
• pp.137-144
• /
• 2013

A delay-locked loop (DLL) that generates a 32-phase clock with the operating frequency of 125 MHz is introduced. The proposed DLL uses a delay line of $4{\times}8$ matrix architecture to improve a differential non-linearity (DNL) of the delay line. Furthermore, a integral non-linearity (INL) of the proposed DLL is improved by calibrating phases of clocks that is supplied to four points of an input stage of the $4{\times}8$ matrix delay line. The proposed DLL is fabricated by using $0.11-{\mu}m$ CMOS process with a 1.2 V supply. The measured operating frequency range of the implemented DLL is 40 MHz to 280 MHz. At the operating frequency of 125MHz, the measurement results shows that the DNL and INL are +0.14/-0.496 LSB and +0.46/-0.404 LSB, respectively. The measured peak-to-peak jitter of the output clock is 30 ps when the peak-to-peak jitter of the input clock is 12.9 ps. The area and power consumption of the implemented DLL are $480{\times}550{\mu}m^2$ and 9.6 mW, respectively.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.6
• /
• pp.156-165
• /
• 2011

This study investigates the horizontal shear behavior of an interface between precast concrete (PC) and topping concrete(RC), and evaluates the horizontal based on the investigations by the experimental. Horizontal shear strength in connected surface is determined by the roughness an interface and the shear reinforcement or not. In this study, the main experimental parameters are the shear reinforcement types in the shape of loop-type and lattice-type, rebar spacing. A total of four specimens were shear strength tested and manufactured. As a result, the horizontal shear strength of reinforced connected surface was found to be controlled by deformation in vertical direction. Comparison of reinforcement shape, the mean initial crack load loop type specimens, the average maximum load and the junction of the average in terms of initial stiffness, respectively 33.7%, 45.9% and 55.2% were large enough. Evaluation results for shear strength equation of existing standard domestic, the loop-type reinforced 2.32 to 4.23 times, lattice-type reinforced 1.65 to 3.06 times appears to be higher. Behavior of interface or strength of structural design criteria was fairly safe side. It does not have any problems in the applied field is considered.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.9
• /
• pp.775-782
• /
• 2016

In this paper, we propose a dual-band GPS antenna using a single-layer coupled-feed structure for improvement of isolation and design complexity. The proposed antenna consists of a central feed patch and outer dual loops, and the loops are electromagnetically fed by the feed patch to induce currents. This feeding network can improve the isolation between antenna elements arranged in small arrays because the magnetic field strength near the antenna is minimized by confining the fields around the dual loops. The isolation characteristics of the proposed antenna are compared with those of the conventional multi-layer patch antenna, and the average field strength and the isolation are improved by 3 dB and 2 dB, respectively, which verifies that the antenna is suitable for small CRPA arrays.

• Journal of Ocean Engineering and Technology
• /
• v.27 no.2
• /
• pp.13-18
• /
• 2013

Most ships and offshore structures are equipped with a variety of pipes, which inevitably contain curved portions. The structural design of these pipes mostly relies on the commercial code, CAESAR-II, which was especially developed for the structural analysis of pipes. This study conducted stress analyses of the same pipe unit, including loops, using both CAESAR-II and MSC/NASTRAN, and compared the results to investigate the characteristics of CAESAR-II. A parametric study was then conducted of the various design variables of pipe loops using CAESAR-II to draw some useful information about the structural characteristics of the loops.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.10
• /
• pp.1103-1108
• /
• 2010

This paper proposes a new type of PIFA with a capacitor structure inserted into the feeding loop. It operates in GSM900, DCS, PCS, and W-CDMA frequency bands. By inserting the capacitor, it shows the effect of lowering the return loss from -2.73 dB to -6.26 dB at the parallel frequency, 2.01 GHz. The improvement of the poor radiation property near the parallel resonance frequency leads to a broadband operation in the upper band, DCS, PCS, and W-CDMA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.5
• /
• pp.551-558
• /
• 2012

This paper presents a dual band loop-type ground antenna using lumped-elements that control the impedance bandwidth and resonant frequency. The dual-band operation of the proposed antenna is realized by inserting an additional resonated loop feed structure into the reference ground antenna. As the proper value of the capacitor and the inductor are chosen, the impedance bandwidth of our antenna with voltage standing wave ratio(VSWR) equal to 3 is 85 MHz and 725 MHz at the 2.45 and 5.5 GHz frequency band, respectively. Its validity is demonstrated via both the computed and measured results. Good antenna patterns and efficiencies are achieved at the dual frequency bands, as well as the physically small antenna element size($10{\times}5mm^2$).

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.9
• /
• pp.1241-1248
• /
• 2010

In large-scale production of hydrogen, a PHE (Process Heat Exchanger) is a key component because the heat required to carry out the Sulfur-Iodine chemical reaction that yields hydrogen is transferred from a VHTR (Very High Temperature Reactor) by the PHE. Korea Atomic Energy Research Institute established a helium gas loop for conducting performance test of components that are used in the VHTR. In this study, as a part of high-temperature structural-integrity evaluation of a designed PHE prototype that is scheduled to be tested in the helium gas loop, we carried out high-temperature structural-analysis modeling, thermal analysis, and thermal-expansion analysis for the designed PHE prototype. An appropriate constraint condition is proposed at the end of the in-flow and out-flow pipelines of the primary and secondary coolants and the proposed constraint condition will be applied to the design of the performance-test loop setup for the designed PHE prototype.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.2 no.4
• /
• pp.199-202
• /
• 2007

In this paper, we examined the operating principle of a passive tag antenna for RFID system in UHF band. Based on the study, we proposed a novel RFID tag antenna which adopts the inductively coupled feeding structure to match antenna impedance to a capacitively loaded commercial tag chip. The proposed tag antenna consists of microstrip lines on a thin PET substrate for low-cost fabrication. The detail structure of the tag antenna were optimized using a full electromagnetic wave simulator of IE3D in conjunction with a Pareto genetic algorithm, and the size of the tag antenna can be reduced up to kr=0.27(2 cm2). We built some sample antennas and measured the antenna characteristics such as a return loss, an efficiency, and radiation patterns. The readable range of the tag antenna with a commercial RFID system showed about 1 to 3 m.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.7
• /
• pp.38-45
• /
• 2006

The superconducting fault current limiters(SFCLs) provide the effect such as enhancement in power system reliability due to limiting the fault current within a few miliseconds. Among various SFCLs we have developed a flux-lock type SFCL and exploited a special design to effectively reduce the fault current according to properly adjustable magnetic field after the short-circuit test. This SFCL consists of two copper coils wound in parallel on the same iron core and a component using the YBCO thin film connected in series to the secondary copper coil. Meanwhile, operating characteristics can be controlled by adjusting the inductances and the winding directions of the coils. To analyze the operational characteristics, we compared closed-loop with open-loop iron core. When the applied voltage was 200[Vrms] in the additive polarity winding, the peak values of the line current the increased up to 30.71[A] in the closed-loop and 32.01[A] in the open-loop iron core, respectively. On the other hand, in the voltages generated at current limiting elements were 220.14[V] in the closed-loop and 142.73[V] in the opal-loop iron core during first-half cycle after fault instant under the same conditions. We confirmed that the open-loop iron core had lower power burden than in the closed-loop iron core. Consequently, we found that the structure of iron core enabled the flux-lock type SFCL at power system to have the flexibility.