Measurement of Rain Attenuation of Microwaves at 12.25GHz in Korea

Abstract. We present here the results of the measurements of rain-induced attenuation in the vertically polarized signal propagating at 12.25GHz during some rain events, which occurred in the rainy season of the year 2001 at Yongin, Korea. The attenuation measured experimentally was compared with that obtained using the International Telecommunication Union Radio Communication Sector (ITU-R) model, the SAM model and the Global model. Our measured results are in good agreement with the ITU-R prediction

Characterization of Rain Specific Attenuation and Frequency Scaling Method for Satellite Communication in South Korea

The attenuation induced by rain is prominent in the satellite communication at Ku and Ka bands. The paper studied the empirical determination of the power law coefficients which support the calculation of specific attenuation from the knowledge of rain rate at Ku and Ka band for Koreasat 6 and COMS1 in South Korea that are based on the three years of measurement. Rain rate data was measured through OTT Parsivel which shows the rain rate of about 50 mm/hr and attenuation of 10.7, 11.6, and 11.3 dB for 12.25, 19.8, and 20.73 GHz, respectively, for 0.01% of the time for the combined values of rain rate and rain attenuation statistics. Comparing with the measured data illustrates the suitability for estimation of signal attenuation in Ku and Ka band whose validation is done through the comparison with prominent rain attenuation models, namely, ITU-R P.618-12 and ITU-R P. 838-3 with the use of empirically determined coefficient sets. The result indicates the significance of the ITU-R recommended regression coefficients of rain specific attenuation. Furthermore, the overview of predicted year-wise rain attenuation estimation for Ka band in the same link as well as different link is studied which is obtained from the ITU-R P. 618-12 frequency scaling method

Kerberos based authentication for inter-domain roaming in wireless heterogeneous network

AbstractAn increased demand in ubiquitous high speed wireless access has led integration of different wireless technologies provided by different administrative domains creating truly a heterogeneous network. Security is one of the major hurdles in such network environment. As a mobile station moves in and out of the coverage area of one wireless network to another, it needs to be authenticated. The existing protocols for authentication of a mobile station are typically centralized, where the home network participates in each authentication process. It requires home network to maintain roaming agreement with all other visiting networks. Moreover, the round trip time to home network results high latency. This paper is focused on developing authentication protocol for wireless network irrespective of the technologies or the administrative domain. We propose a secure protocol which adopts strong features of Kerberos based on tickets for rigorous mutual authentication and session key establishment along with issuance of token so that the mobile station can have access to not only the roaming partner of home network but also to the roaming partner of previous visited networks. The performance evaluation and comparative analysis of the proposed protocol is carried out with the already implemented standard protocols and most remarkable research works till date to confirm the solidity of the results presented

A New Fractal-Based Miniaturized Dual Band Patch Antenna for RF Energy Harvesting

The growth of wireless communications in recent years has made it necessary to develop compact, lightweight multiband antennas. Compact antennas can achieve the same performance as large antennas do with low price and with greater system integration. Dual-frequency microstrip antennas for transmission and reception represent promising approach for doubling the system capacity. In this work, a miniaturized dual band antenna operable at 2.45 and 5.8 GHz is constructed by modifying the standard microstrip patch antenna geometry into a fractal structure. In addition to miniaturization and dual band nature, the proposed antenna also removes unwanted harmonics without the use of additional filter component. Using a finite-element-method-based high frequency structure simulator (HFSS), the antenna is designed and its performance in terms of return loss, impedance matching, radiation pattern, and voltage standing wave ratio (VSWR) is demonstrated. Simulation results are shown to be in close agreement with performance measurements from an actual antenna fabricated on an FR4 substrate. The proposed antenna can be integrated with a rectifier circuit to develop a compact rectenna that can harvest RF energy in both of these frequency bands at a reduction in size of 25.98% relative to a conventional rectangular patch antenna

CPW-Fed Wideband Circular Polarized Antenna for UHF RFID Applications

We propose a wide bandwidth antenna with a circular polarization for universal Ultra High Frequency (UHF) radio-frequency identification (RFID) reader applications. To achieve a wide 3 dB axial ratio (AR) bandwidth, three T-shaped microstrip lines are inserted into the ground plane. The measured impedance bandwidth of the proposed antenna is 480 MHz and extends from 660 to 1080 MHz, and the 3 dB AR bandwidth is 350 MHz and extends from 800 to 1155 MHz. The radiation pattern is a bidirectional pattern with a maximum antenna gain of 3.67 dBi. The overall size of the proposed antenna is 114 × 114 × 0.8 mm3

The current status of emergency contraception use in reproductive-aged Korean women: a population-based internet survey

ObjectiveThis study was conducted to assess the current status of emergency contraception (EC) use in reproductive-aged Korean women.Materials and methodsThis study utilized a population-based, cross-sectional online survey using a self-completed questionnaire in women aged 20-44 years who had visited a clinic in the previous six months for contraception counseling. Reason for use, anxiety, and counseling for further contraception at EC use were analyzed according to age, history of childbirth, and contraceptive failure in EC users.ResultsAmong 1,011 respondents, 461 (45.6%) had experience with EC use. Younger age, need for EC due to inadequate contraception, and high anxiety were highly prevalent among EC users. However, women in the 20s were less likely to get counseling for further contraception at EC use. Additionally, the proportions of women who used EC due to inadequate contraception during sexual intercourse and who experienced high anxiety were lower among women who had a history of childbirth. Women who had a history of contraceptive failure worried less about EC use.ConclusionOur findings offer insight for developing and improving individualized strategies for appropriate contraception, especially in young Korean EC users

The complete chloroplast genome sequence of Abies nephrolepis (Pinaceae: Abietoideae)

AbstractThe plant chloroplast (cp) genome has maintained a relatively conserved structure and gene content throughout evolution. Cp genome sequences have been used widely for resolving evolutionary and phylogenetic issues at various taxonomic levels of plants. Here, we report the complete cp genome of Abies nephrolepis. The A. nephrolepis cp genome is 121,336 base pairs (bp) in length including a pair of short inverted repeat regions (IRa and IRb) of 139 bp each separated by a small single copy (SSC) region of 54,323 bp (SSC) and a large single copy region of 66,735 bp (LSC). It contains 114 genes, 68 of which are protein coding genes, 35 tRNA and four rRNA genes, six open reading frames, and one pseudogene. Seventeen repeat units and 64 simple sequence repeats (SSR) have been detected in A. nephrolepis cp genome. Large IR sequences locate in 42-kb inversion points (1186 bp). The A. nephrolepis cp genome is identical to Abies koreana’s which is closely related to taxa. Pairwise comparison between two cp genomes revealed 140 polymorphic sites in each. Complete cp genome sequence of A. nephrolepis has a significant potential to provide information on the evolutionary pattern of Abietoideae and valuable data for development of DNA markers for easy identification and classification

Measurement of Blood Pressure Using an Arterial Pulsimeter Equipped with a Hall Device

To measure precise blood pressure (BP) and pulse rate without using a cuff, we have developed an arterial pulsimeter consisting of a small, portable apparatus incorporating a Hall device. Regression analysis of the pulse wave measured during testing of the arterial pulsimeter was conducted using two equations of the BP algorithm. The estimated values of BP obtained by the cuffless arterial pulsimeter over 5 s were compared with values obtained using electronic or liquid mercury BP meters. The standard deviation between the estimated values and the measured values for systolic and diastolic BP were 8.3 and 4.9, respectively, which are close to the range of values of the BP International Standard. Detailed analysis of the pulse wave measured by the cuffless radial artery pulsimeter by detecting changes in the magnetic field can be used to develop a new diagnostic algorithm for BP, which can be applied to new medical apparatus such as the radial artery pulsimeter

Abdominal Actinomycosis Associated with a Sigmoid Colon Perforation in a Patient with a Ventriculoperitoneal Shunt

Abdominal actinomycosis causing hydronephrosis in a patient with a ventriculoperitoneal shunt is very rare. A 27-year-old female patient was admitted complaining of lower abdominal pain. She had undergone ventriculoperitoneal shunt surgery 10 years ago. Abdominal Ultrasonography and a CT scan demonstrated an inflammatory mass in the lower left quadrant of the abdomen causing obstructive hydroureter and hydronephrosis. Laparotomy revealed a diffusely infiltrating mass involving the small bowel, mesentery, and sigmoid colon, and a 1 cm perforation in the sigmoid colon. Actinomycosis was diagnosed upon histological examination. After treatment with antibiotics and surgery, the patient's condition improved

MIMO Antenna System With Pattern Diversity for Sub-6 GHz Mobile Phone Applications

A MIMO antenna system is designed and presented for sub-6 GHz mobile phone applications. The proposed antenna design consists of six loop-type radiation elements. From the six elements, four elements are placed at the corners of the mobile phone PCB by following pattern diversity configuration, while the rest of the two elements are placed in the center of the PCB. Furthermore, a $50\Omega$ coaxial connector is utilized to feed the antenna elements. From the presented results, it is demonstrated that the elements placed at the edges are resonating at 2.5 GHz, and the center placed elements provide resonance at 3.5 GHz. Moreover, according to S11 ≤ −6 dB, the impedance bandwidth for both the bands is 790 MHz (2.3-3.09 GHz) and 1.18 GHz (2.99-4.17 GHz), respectively; while for S11 ≤ −10 dB, the impedance bandwidth for both the bands is noted to be 340 MHz (2.38-2.72 GHz) and 650 MHz (3.17–3.84 GHz), respectively. A gain of more than 4 dBi and >85% radiation efficiency are achieved for the single radiation element. The presented antenna design also provides sufficient radiation coverage supporting different sides of the mobile phone PCB. In addition, the effects of the human hand and head on antenna’s performance are studied and it was observed that the proposed antenna system provides acceptable properties in the data mode and talk mode