• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.4C
• /
• pp.386-394
• /
• 2010

In this paper, we propose an adaptive coordinated Tx-Rx beamforming scheme for inter-user interference cancellation, when a BS communicates with multiple users that each has multiple receive antenna. The conventional coordinated Tx-Rx beamforming scheme uses a fixed multi-stream per user regardless of the instantaneous channel states, that is, both user with ill-conditioned and well-conditioned channels have the same number of data streams. However, in the proposed adaptive coordinated Tx-Rx beamforming scheme, we select the number of streams per user to solve the inefficient problem of the conventional coordinated Tx-Rx beamforming. As a result of applying the adaptive coordinated Tx-Rx beamforming scheme, the BER performance is improved. Simulation results show that the proposed algorithm outperforms the conventional coordinated Tx-Rx beamforming algorithm by 2.5dB at a target BER of $10^{-2}$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.7
• /
• pp.1156-1160
• /
• 2000

The cancellation loop configuration for power amplifier module is proposed to reject the RX signals using feed-forward technique. In this paper, we implement the 1W-ampilfier module of WLL band to show validity of the proposed cancellation loop. The power amplifier module with the proposed cancellation loop can provide low TX insertion path loss due to duplexer and choice of loose RX attenuation characteristic for various wireless communication systems. It shows at least 90 % improved RX rejection characteristic compared to power amplifier module without RX band cancellation loop.

• Journal of the Korea Society of Computer and Information
• /
• v.24 no.5
• /
• pp.19-26
• /
• 2019

In this paper, we consider the D2D Transmitter(Tx) and Receiver(Rx) pair assignment problem in the cellular system. Sharing the resource of the cellular system, D2D users may cause interference to the cellular system, though it is beneficial to improve the D2D user Capacity. Therefore, to protect the cellular users, D2D transmit power should be carefully controlled. Previously, optimal Tx-Rx assignment to minimize the total transmit power of users was investigated. Accordingly, the iterative algorithm to find the optimum Tx-Rx asignment was obtained. In this work, we consider the case where Tx group users becomes Rx group users, and Rx group users become Tx group users. We prove that the Tx-Rx assignment problem has the duality property. We present the numerical examples that show the duality between U-link and D-link.

• International Journal of Human Ecology
• /
• v.12 no.2
• /
• pp.1-12
• /
• 2011

Many pharmaceutical products are available through prescription (Rx) only status. As a result, access to physicians and insurance coverage play a key role in the use of these products, and therefore may affect the population to whom advertising is targeted at. The movement of pharmaceutical products from prescription (Rx) to Over-the-Counter (OTC), or Rx-to-OTC switch changes the cost of acquiring the drug and therefore may change the incentives manufacturers have at targeting particular population segments. This study examines whether Rx-to-OTC switch changes the frequency and the distribution of who is exposed to pharmaceutical advertising. Using an archive of pharmaceutical advertisements and National Consumer Survey, this study examines how individuals with particular demographic characteristics are exposed to pharmaceutical advertisements before and after drugs are moved from Rx to OTC. The results provide evidence that individual's advertising exposure increases after Rx-to-OTC switch. Moreover, the increase in advertising exposure is greater for the low socioeconomic status (SES) consumers which implies they may get more information about the disease, treatment and product after the Rx-to-OTC switch through advertising. If low SES consumers have more exposure to the advertising after products switched to OTC, then FDA policies regulating this switch should recognize the potential role of advertising providing access to health-related information.

• The Journal of Information Technology
• /
• v.7 no.1
• /
• pp.57-67
• /
• 2004

Data broadcast has attracted a lot of attention as an efficient way of disseminating data to very large client populations. The main motivation of data broadcast systems is that the number of clients that they serve can grow arbitrarily large without any effect on their performance. The performance of broadcast system depends mainly on client caching strategies and on data broadcast scheduling mechanisms. This paper addresses the latter issue and proposes a new broadcast scheduling scheme, named RxW$^{\alpha}$, that is suitable to data broadcast systems. This paper also evaluates the performance of RxW$^{\alpha}$ on the basis of a simulation model. The performance results indicate that RxW$^{\alpha}$ is capable of improving the performance in the variance of response time significantly, showing a reasonable performance in the response time.

• Journal of information and communication convergence engineering
• /
• v.17 no.3
• /
• pp.221-226
• /
• 2019

In this work, a transmitter/receiver front-end module (T/R FEM) with an automatic Tx/Rx switching scheme for a 2.4 GHz microwave power transfer is developed for a retro-reflective beamforming scheme. Recently, research on wireless power transfer techniques has moved to wireless charging systems for mobile devices. Retro-reflective beamforming is a good candidate for tracking the spatial position of a mobile device to be charged. In Tx mode, the T/R FEM generates a minimum of 1 W. It also comprises an amplitude and phase monitoring port for transmitting RF power. In Rx mode, it passes an Rx pilot signal from a mobile device to a digital baseband subsystem to recognize the position of the mobile device. The insertion loss of the Rx signal path is 4.5 dB. The Tx and Rx modes are automatically switched by detecting the Tx input power. This T/R FEM is a design example of T/R FEMs for wireless charging systems based on a retro-reflective beamforming scheme.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.8
• /
• pp.830-838
• /
• 2003

In this paper, TX/RX dual operation microstrip single antenna for satellite communication is designed, analyzed, fabricated and measured. TX/RX frequency ranges are 14.0∼l4.5 GHz, 11.7∼12.75 GHz in respectively and vertical and horizontal polarizations are used for TX and RX. This antenna uses microstrip direct feeding for RX and aperture coupled strip-line feeding for TX and accommodates stacked elements for a high directivity and wide impedance bandwidth. In an analysis of single element, FDTD and MOM was compared and FDTD analysis was more accurate because of the consideration of finite structure and imperfect two ground planes. The proposed structure facilitates generally to an extension of two dimensional array and lower an unwanted radiation by strip-line feed in TX. TX/RX 8${\times}$4 array has a return loss below -10 dB, -14 dB in TX, RX respectively and a gain ranging from 19.1∼20.7 dB in TX, 21.2∼21.8 dB in RX which has a radiation efficiency of 43∼5l %, 52∼57 %.

• The Journal of Korean Medicine
• /
• v.19 no.2
• /
• pp.420-438
• /
• 1998

Herba Xanthii(HX), Radix Xantluii(RX) and Fructus Xanthii(FX) is one of the oriental medicine that has been used for the treatment of such infectious diseases and tumors. However, the mechanism of the drug is not investigated much. This study was done to know the effects of HX, RX and FX extract on the such innate immunities as phagocytic function and reactive radical formtions from phagocytes and the such acquired immunities as humoral and cell-mediated immunities. The followings are the results obtained from this study: 1. HX2 and FX1 groups increases the in vivo phagocytic activity of mononuclear phagocytes. 2. HXB, RXB, RXC, FXB and FXC groups increase the in vitro phagocytic activities. 3. RXB group stimulated the macrophages to produce nitric oxide in the presence of $interferon-{\gamma}$ $(IFN-{\gamma})$. 4. HX and RX whole groups increased the luminol-amplified reactive oxygen intermediate production in vivo. 5. HX whole and RX1, FX2 groups increased the lucigenin-amplified reactive oxygen intennediate production in vivo. 6. HXC group only increased the luminol-amplified reactive oxygen intermediate production in vitro. 7. HXB, FXB and FXC groups increased the lucigenin-amplified reactive oxygen intermediate production in vitro. 8. HX2, RX1 and FX whole groups increased the hemolysin formations from B cells. 9. HX, RX and FX whole groups significantly increased the rosette forming cells from the spleen. 10. HX, RX and FX whole groups significantly decreased the delayed-type hypersensitivity measured by footpad swelling. The above results demonstrate that HX, RX and FX has enhancing effects on innate immunity selectively and decreasing effects on delayed-type hypersensitivity of cell-mediated immunity according to medicinal part and diluted condition. This immunomodulating effects of HX, RX and FX might be responsible for the treatment of immune-mediated disorders.

• Journal of Pharmaceutical Investigation
• /
• v.27 no.4
• /
• pp.303-311
• /
• 1997

Proliposomal patch of clenbuterol, ${\beta}_2-agonist$ bronchodilator, was prepared and its feasibility as a novel transdermal drug delivery system was examined. Proliposomal granules containing clenbuterol was prepared by a standard method using sorbitol and lecithin with (Rx 2) or without cholesterol (Rx 1). The porous structure of sorbitol in the proliposomes was maintained allowing tree flowability of the granules. Following contact with water, the granules were converted probably to liposomes almost completely within several minutes. It indicates that proliposomes may be hydrated, when they are applied on the skin under occlusive condition in vivo, by the sweat to form liposomes. Clenbuterol release from Rx 1 and Rx 2 proliposomes to pH 7.4 isotonic phospate buffer (PBS) across cellulose membrane (mol. wt. cut-off of 12000-14000) was retarded significantly compared with that from the mixture of clenbuterol powder and blank proliposomes. Interestingly, proliposomes prepared with lecithin and cholesterol (i.e., Rx 2 proliposomes) showed much more retarded release of clenbuterol than proliposomes prepared only with lecithin (i.e.. Rx 1 proliposomes), indicating that clenbuterol release from proliposomes can be controlled by the addition of cholesterol to the proliposomes. Proliposomal patches were prepared using PVC film as an occlusive backing sheet, two sides adhesive tape (urethane, 1.45 mm thickness) as a reservoir for proliposome granules and Millipore MF-membrane (0.45 mm pore size) as a drug release-controlling membrane. Rx 1 or Rx 2 proliposomes containing 4.6 mg of clenbuterol were loaded into the reservoir of the patch. Clenbuterol release from the patches to pH 7.4 PBS was determined using USP paddle (50 rpm)-over-disc release method. Clenbuterol release from the proliposomal patches was much more retarded even than from a matrix type clenbuterol patch (Boehringer Ingelheim ltd). Being consistent with clenbuterol release from the proliposomal granules, the release from the patches was highly dependent on the presence of cholesterol in the proliposomes : Patches containing Rx 2 proliposomes showed several fold slower drug release than patches containing Rx 1 proliposomes. When the patch containing Rx 1 proliposomes was applied on to the back of a hair-removed rat, clenbuterol concentration in the rat blood was maintained during 6-72 hrs. Transdermal absorption of clenbuterol from the patch was accelerated when the patch was prehydrated with 50 ml of pH 7.4 PBS before topical application. Above results indicate that sustained transdermal delivery of clenbuterol is feasible using proliposomal patches if the cholesterol content and pore size of the release rate-controlling membrane of patches, for example, are appropriately controlled.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.2
• /
• pp.308-315
• /
• 2001

In this paper, a new power amplifier is proposed for reduction of amplified RX band noise signals as well as intermodulation distortion signals using feedforward technique. This power amplifier is implemented for IMT-2000 basestation TX frequency band. Both TX band intermodulation distortion signals and RX band noise signals are reduced by controlling variable attenuator, phase shifter and error amplifier. The proposed power amplifier, which contains two loops-intermodulation distortion signals cancellation loop and RX band noise signals cancellation loop, can provide duplexer with low TX path insertion loss for various wireless communication systems due to choice of loose RX attenuation characteristic. The principle of the proposed amplifier is described graphically based on the conceptual schematic diagram. A two-tone test for power amplifier is done at 2.14GHz with frequency spacing of 5MHz, and RX band rejection test is done over RX full band of 60MHz with 1.95GHz center frequency. Experimental results represent that the cancellation performance of intermodulation distortion signals and RX band noise signals are more than 3 1dB and 21dB, respectively.