• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.292-295
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• 2005

Variable optical attenuators (VOA) made of low-loss fluorinated polymers are demonstrated which shows a low operating power less than 30 mW due to the superior thermo-optic effect of polymer material and a low insertion loss less than 1.0 dB by incorporating highly fluorinated polymers to reduce the absorption loss at 1550 nm. An attenuator-integrated low-crosstalk polymeric digital optical switch (DOS) is also demonstrated. The switch and attenuator shares a single connected electrode which is controlled by a single current source. Due to the simple structure of the integrated attenuator, the device length is reduced to 1 cm so as to provide low insertion loss of 0.8 and 1.1 dB for 1300 and 1550 nm, respectively. The attenuator radiates remained optical signal on the switch-off branch in order to decrease the switching crosstalk to be less than -70 dB with an applied electrical power of 200 mW.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.158-163
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• 2008

Muffler design in the exhaust system is critical to provide for low noise in shipboard spaces. In an attempt to effectively design the low noise muffler, it is important to evaluate the performance of the muffler considering not only the noise, but also pressure drop as well. For this purpose, a test system of large exhaust muffler for ship propulsion systems was designed based on ISO 7235. The substitution test for determining both the insertion loss and pressure drop of mufflers was carried out. A ship exhaust muffler is considered as a test example and the insertion loss and pressure drop are obtained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1237-1242
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• 2008

A muffler design in the exhaust system is critical to provide fur low noise in shipboard spaces. In an attempt to effectively design the low noise muffler, it Is important to evaluate the performance of the muffler considering not only the noise, but also pressure drop as well. For this purpose, a test system of large exhaust mufflers fur ship propulsion systems was designed based on ISO 7235. The substitution test fur determining both the insertion loss and pressure drop of mufflers was carried out. A ship exhaust muffler is considered as a test example and the insertion loss and pressure drop were obtained.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.1
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• pp.9-14
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• 2012

In this study, the diplexer used a separator or a combine of signals was designed and its characteristics were investigated. The diplexer consists of two fixed tuned bandpass filter such as low pass filter(LPF) and high pass filter(HPF) sharing a common part and was simulated. The diplexer with micro-strip structure was fabricated. The LPF of diplexer has insertion loss of -0.4 dB, return loss of -30 dB and 1.6 GHz cut-off frequency and HPF has insertion loss of -0.8 dB, return loss of -30 dB and 1.9 GHz cut-off frequency, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.128-134
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• 2010

In this paper, a high-power 20-way stripline power divider with low insertion loss and low side lobe level is successfully designed, fabricated and measured as a feed network for an S-band linear array antenna having Dolph-Chebyshev current distribution which has a narrow beam width and very low side lobe level (SLL). The 20-way stripline power divider consists of an 8-way power divider, three 4-way power dividers and three ring hybrids. It utilizes a T-junction structure as a basic element for power dividing. Notches and modified input/output N-to-stripline transitions are used for improving insertion loss and return loss. The fabricated power divider shows insertion loss less than 0.3 ㏈ and rms phase mismatch less than 8o in the full bandwidth. A final 40-way power divider is synthesized by combining symmetrically two 20-way power dividers and is expected to have SLL over 40 dB, based on the measured results of the 20-way power divider.

• International Journal of Computer Science & Network Security
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• v.24 no.7
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• pp.118-122
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• 2024

The dielectric material is a basic element which impacts considerably on a microstrip structure performances. This project demonstrates how filter performances such as gain, bandwidth, return loss and insertion loss change proportionally with substrate material variation. The RT/Duroid 5880 and the FR-4 are two dielectric materials proposed as substrates of a low pass microstrip filter. The design and simulation are done on ADS software. The transmission and reflection characteristics show that the RT/ Duroid 5880 as a dielectric substrate permits to obtain better performance as compared to the FR-4 substrate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.301-310
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• 2004

In this paper, a compact dual-mode filter structure without coupling gaps is proposed. The novel design is achieved by embedding a pair of equal crossed slots and spur-lines. Without coupling gaps between feed lines and patch resonator, the new filter can provide low insertion loss. It is found that this design has wide coupling range for dual-mode operation. It means that these characteristics of the proposed filter can reduce uncertainty in fabrication. By using two PIN diodes mounted inside a pair of spur-lines, the proposed structure works as a switchable filter. Also, it has a size reduction of about 34.7 %, compared with conventional dual-mode filters.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.431-434
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• 2004

The design, simulation, modeling and measurement of a RF switch module for GSM applications were presented in this paper. switch module were simulated by ADS and constructed using a LTCC multi-layer switching circuit and integrated low pass filter, designed to operate in the GSM band. Insertion and return losses at 900 MHz of the low pass filters were designed to lower than 0.3 dB and higher than 12.7 dB respectively. The switch module constructed, contained 10 embedded passives and 3 surface mounted components integrated on $4.6{\times}4.8{\times}1.2$ m volume, 6-layer integrated circuit. The insertion loss of switch module at m MHz were around 11 dB.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2006.10a
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• pp.255-267
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• 2006

LTCC Technology is very suitable for 60 GHz application $\blacksquare$ LTCC substrate shows low loss at 60 GHz. - low insertion and return losses $\blacksquare$ Microstrip or CBCPW line is sultable for transmission lines at 60 GHz. - low loss (0.1dB/mm) $\blacksquare$ Single ribbbon bonding is adequate for interconnection - simple - low loss (0.1dB/bonding) $\blacksquare$ Characteristics of MMIC module - Gain difference (${\Delta}S21$) : 0.4 dB

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.7
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• pp.693-698
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• 2009

Various acoustic tests were carried out to investigate the acoustic performance of diesel engine exhaust silencers. In order to consider flow effects, the test facility was set up composed of fan, duct and silencer. Using the test facility, insertion loss tests were carried out to improve the acoustic performance in the low-frequency ranges. Through a series of tests, it was found out that the array resonators having multi-perforated holes inside the exhaust silencer, might be very effective in the low frequency range. Consequently, the hybrid-type silencer which is the combination of reflective silencer with array resonators and conventional absorptive silencer, was proposed and its high performance in the low-frequency range was also verified.