Recent advances in millimeter- and submillimeter-wave astronomy demand heterodyne receivers that simultaneously provide wide intermediate-frequency (IF) bandwidth and low receiver noise temperature. In this work, we present the design, fabrication, and experimental validation of a wide-IF (8–16 GHz) superconductor-insulator-superconductor (SIS) mixer for the 150 GHz band. The device employs a series array of four Nb/AlOx/Nb SIS junctions with a target RF embedding impedance near the optimum impedance of 31 Ω, and it is integrated with a pentagonal probe and a WR 6.5 waveguide for RF broadband coupling. Full-circuit simulations conducted in SuperMix were used to define the layout, and the performance of the fabricated mixer was evaluated in a 4 K test cryogenic receiver using hot/cold-load measurements over the 8–16 GHz IF band in double-sideband (DSB) mode. At a local oscillator (LO) frequency of 154 GHz, the mixer exhibits a maximum DSB conversion gain of 6 dB with a corresponding receiver noise temperature (Trx) ∼ 29 K. Across the IF band, Trx averages 43 K with a range of 25–76 K. These results establish the developed mixer as a promising candidate for next-generation wide-IF astronomical receivers.

Marketers and retailers are increasingly interested in grabbing the opportunity to reach the consumer at the right time and place with a smart phone. Depending on Location Based Advertising (LBA) and associated sensors with the IBeacon technology, marketers can determined the consumer’s favorite products through his search history and previous purchase activities furthermore his location in-store. So, marketers and retailers pay more attention to in-store mobile LBA. In this work, the modified LBA in-store framework are constructed. This model proposed that the temporal time, type of information and the variety of receiver of mobile in-store LBA affect the Purchase intention in retail stores.

PURPOSES: The purpose of this research is to analyze the characteristics of panels that affect the evaluating results of riding quality and to evaluate the appropriateness of roughness management criteria based on ride comfort satisfaction. METHODS: In order to analyze the influence of panel characteristics of riding quality, 33 panels, consisting of civilians and experts, were selected. Also, considering the roughness distribution of the expressway, 35 sections with MRI ranging from 1.17 m/km to 4.65 m/km were selected. Each panel boarded a passenger car and evaluated the riding quality with grades from 0 to 10, and assessed whether it was satisfied or not. After removing outlier results using a box plot technique, 964 results were analyzed. An ANOVA was conducted to evaluate the effects of panel expertise, age, driving experience, vehicle ownership, and gender on the evaluation results. In addition, by using the receiver operating characteristics (ROC) curve, the MRI value, which can most accurately evaluate the satisfaction with riding quality, was derived. Then, the compatibility of MRI was evaluated using AUC as a criterion to assess whether the riding quality was satisfactory. RESULTS: Only the age of the panel participants were found to have an effect on the riding quality satisfaction. It was found that satisfaction with riding quality and MRI are strongly correlated. The satisfaction rate of roughness management criteria on new (MRI 1.6 m/km) and maintenance (MRI 3.0 m/km) expressways were 95% and 53%, respectively. As a result of evaluating the roughness management criteria by using the ROC curve, it was found that the accuracy of satisfaction was the highest at MRI 3.1-3.2 m/km. In addition, the AUC of the MRI was about 0.8, indicating that the MRI was an appropriate index for evaluating the riding quality satisfaction. CONCLUSIONS: Based on the results, the distribution of the panels’age should be considered when panel rating is conducted. From the results of the ROC curve, MRI of 3.0 m/km, which is a criterion of roughness management on maintenance expressways, is considered as appropriate.

This work is for evaluating the intentional interference against GNSS receiver on surface ships. The case study was performed under considerable assumptions based on the GPS jamming events around the Korean Peninsula in recent years. The propagation loss

We develop a radio receiver system operating at λ ~ 1.3 mm for the 6 m telescope of Seoul Radio Astronomy Observatory. It consists of a dual polarization receiver, a couple of IF processing units, two FFT spectrometers, and associated software. By adopting sideband-separating superconductor mixers with image band terminated to waveguide load at 4.2 K, we achieve TRX ≤ 100 K and Tsys less than 150 K at best weather condition over 210-250 GHz frequency range. The intermediate frequency signal of 3.5-4.5 GHz is down converted to 0-1 GHz and fed into the FFT spectrometers. The spectrometer covers 1 GHz bandwidth with a spectral resolution of 61 KHz. Test observations are conducted toward several radio sources to evaluate the performance of the system. Aperture and beam efficiencies measured by observing planets are found to be typically 44  59% and 47  61%, respectively over the RF band, which are consistent with those measured at 3 mm band previously.

We have developed superconducting mixer receivers for 129 GHz VLBI observation in Korean VLBI Network (KVN). The developed mixer has a radial waveguide probe with simple transmission line L-C transformer as a tuning circuit to its 5 series-connected junctions, which can have 125 - 165 GHz as the operation radio frequency (RF). For intermediate frequency (IF) signal path a high impedance quarter-wavelength line connects the probe to one end of symmetric RF chokes. The double side band (DSB) receiver noise of the mixer was about 40 K over 4 - 6 GHz IF band, whereas we achieved the uncorrected single side band (SSB) noise temperature of about 70 K and better than 10 dB image rejection ratio in 2SB configuration with 8 - 10 GHz IF band. Insert-type receiver cartridges employing the mixers have been under commission for KVN stations.

이동 전화기의 사용이 급증하면서 이동 전화기와 연계된 부가서비스의 소비도 새로운 연구 분야로 부각되고 있다. 본 연구에서는 이동전화의 통화 연결음(ring-back-tone, 이하 RBT)이 통화 상대자의 퍼스널리티를 평가하는 데 어떤 영향을 미치는 지에 대하여 살펴보았다. 특히, 본 연구의 선행연구를 통한 발견점을 바탕으로 통화 상대자를 충분히 알고 있는 경우와 모르는 경우로 구분하여, 각각에 있어 통화 상대자의 개방성, 외향성, 신경성의 3요인에 대하여 RBT에 따른 평가수치의 변화를 관찰하였다. 개방성, 외향성, 신경성의 3요인에 대한 평가를 위해 각 요인 별 네 개의 평가항목들을 선택하여 총 열두 개의 형용사로 구성된 평가 도구를 실험에 활용하였다. 본 연구의 선행연구에서는 RBT 선정을 위하여 예비 실험을 진행하였으며, 예비 실험에서는 실험에 참여한 피실험자들에게 통화 연결음으로 사용한 17곡의 음악을 무작위한 순서로 들려주고, 각 음악에 대한 개방성, 외향성, 신경성에 대한 특성을 평가하게 하였다(N=15). 이 중 퍼스널리티의 특성이 비교적 크게 구분되는 3곡을 선택하여 실험 I과 실험 II에서 통화 연결음으로 사용하였다. 실험 I에서는 피실험자들을 4개의 피실험자 그룹으로 구분하여 초면인 통화 상대자에게 전화를 걸어 인터뷰를 진행하였으며(N=60), 피실험자 그룹에 따라 다른 통화 연결음을 들려주었다. 실험 결과, 통화 연결음에 따라 통화 상대자의 퍼스널리티 평가가 영향을 받는다는 것을 확인할 수 있었고(p<0.001), 구체적으로는 개방성(r=0.722, p<0.001)과 외향성(r=0.753, p<0.001) 의 평가 결과에서 RBT와 통화 상대자의 퍼스널리티 간에 높은 양의 상관관계가 있음을 밝혀낼 수 있었다. 반면, 실험 II에서는 피실험자가 통화 상대자를 이미 알고 있는 경우에 한하여 실험 I과 동일한 실험을 진행하였는데(N=40), 피실험자가 이미 알고 있는 통화 상대방에 대한 정보로 인하여 통화 연결음의 효과가 감소 될 것이라고 가정하였으며, 이를 실험 결과에서 입증할 수 있었다.