• Title, Summary, Keyword: PAM

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OFDM-Based SSB System using DCT and DHT (DCT와 DHT를 사용하는 OFDM 기반의 SSB 시스템)

  • An, Changyoung;Kim, Byeongjae;Ryu, Heung-Gyoon
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.8
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    • pp.20-25
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    • 2017
  • In this paper, we propose an OFDM-Based SSB System using DCT and DHT transform. The proposed system presents the same waveform as the SSB modulation. The proposed system generates SSB spectrum which are USB and LSB spectrum, also the proposed system can transmit PAM signal through USB and the other PAM signal through LSB. Additionally, we propose how to resolve the center frequency interference problem between USB and LSB. We confirm the simulation result by MATLAB program. The simulation result show the proposed system can transmit PAM signal through only half of spectrum of conventional OFDM system.

Simultaneous Imaging Using Combined Optical Coherence Tomography (OCT) and Photoacoustic Microscopy (PAM) (광간섭 단층 촬영 장치와 광음향 현미경의 결합을 통한 동시 이미지 획득 연구)

  • Kim, Sehui;Lee, Changho;Han, Seonghoon;Kang, Hyun Wook;Oh, Junghwan;Kim, Jeehyun;Kim, Chulhong
    • Journal of Biomedical Engineering Research
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    • v.34 no.2
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    • pp.91-96
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    • 2013
  • In this study, we developed an integrated optical coherence tomography - photoacoustic microscopy (OCT-PAM) system to simultaneously provide optical absorption and scattering information. Two different laser sources, such as a pulsed laser for PAM and a superluminescent diode for OCT, were employed to implement the integrated OCT-PAM system. The performance of the OCT-PAM system was measured by imaging carbon fibers. We then imaged black and white hairs to demonstrate the simultaneous OCT-PAM imaging capabilities. As a result, OCT can produce 3-D images of both black and white hairs, whereas PAM is only able to image the black hair due to strong optical absorption of black hair.

Limiting user process method based on PAM against DoS attacks (DoS 공격에 대비한 PAM 기반 사용자 프로세스 제한 기법)

  • Lee, Jae-Ung;Jung, Sung-Jae;Bae, Yu-Mi;Jang, Rae-Young;Soh, Woo-Young
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.309-312
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    • 2016
  • Considering that interkorean relations got worse and worse recently, cyber terror of North Korea has seriously become a possibility. Therefore, DoS(Denial of Service), a typical way of cyber terror, is becoming a big issue. Consequently, people are growing more and more interested in information security. Internal DoS attacks, out of a variety of ways of Dos attacks, include disks and memories and shortages of process resources. PAM(Pluggable Authentication Module) is one of the ways of preventing internal DoS attacks in Linux system. This paper provides with a method to internally respond to dos attacks and efficiently prevent shortages of resources by utilizing PAM.

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Design of the PAM with High Linearity and Efficiency for Wibro (고선형성, 고효율의 Wibro용 PAM 설계)

  • Oh Inn-Yeal;Kim Tae-Soo;Rhe Kun-Moo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.6
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    • pp.519-528
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    • 2006
  • This thesis is regarding of fabricating wibro PAM. First of all, we need to set specification based on link budget for wibro communication circumstance in order to develop PAM, then we decided specification concerning of wibro PAM by considering TTAS_Ko_06_0082R1 which is standarded in Korea, and IEEE Std. 802. 16d/e which is international standard. We selected the Doherty structure to increase efficiency, and pre-distorter structure to increase linearity. The fabricated PAM has not only a result of $26.5dB{\pm}1.0dB$ gain characteristics and maximum of -14 dB return loss characteristics in full frequency bands and full output ranges, but also a result of 37 dBc at 4 tone IMD characteristics which is improved result of 843 and a result of 31 dBc spurious characteristics which is improved result of 5 dB at 4.77 MHz offset point in status of having 27 % efficiency in the 26 dBm high power amplifier output signal. We confirmed the suggested structure is better than others by comparing with normal structure, balanced structure and Doherty structure without predistorter.

Preparation of Ion Exchange Membranes for Fuel Cell Based on Crosslinked Poly(vinyl alcohol) with Poly(acrylic acid-co-maleic acid)

  • Kim, Dae-Sik;Park, Ho-Bum;Lee, Chang-Hyun;Lee, Young-Moo;Moon, Go-Young;Nam, Sang-Yong;Hwang, Ho-Sang;Yun, Tae-II;Rhim, Ji-Won
    • Macromolecular research
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    • v.13 no.4
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    • pp.314-320
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    • 2005
  • Crosslinked poly(vinyl alcohol) (PVA) membranes were prepared at various crosslinking temperatures using poly(acrylic acid-co-maleic acid) (PAM) containing different PAM contents. The thermal properties of these PVA/PAM membranes prepared at various reaction temperatures were characterized using differential scanning calorimetry (DSC). The proton conductivity and methanol permeability of PVA/PAM membranes were then investigated as PAM content was varied from 3 to 13 wt%. It was found that the proton and methanol transport were dependent on PAM content in their function both as crosslinking agent and as donor of hydrophilic -COOH groups. Both these properties decreased monotonously with increasing PAM concentration. The proton conductivities of these PVA/PAM membranes were in the range from $10^{-3}\;to\;10^{-2}S/cm$ and the methanol permeabilities from $10^{-7}\;to\;10^{-6}cm^{2}/sec$. In addition, the effect of operating temperature up to $80^{\circ}C$ on ion conductivity was examined for three selected membranes: 7, 9 and 11 wt% PAM membranes. Ion conductivity increased with increasing operating temperature and showed and S/cm at $80^{\circ}C$, respectively. The effects of crosslinking and ionomer group concentration were also examined in terms of water content, ion exchange capacity (IEC), and fixed ion concentration. In addition, the number of water molecules per ionomer site was calculated using both water contents and IEC values. With overall consideration for all the properties measured in this study, $7{\sim}9\;wt%$ PAM membrane prepared at $140^{\circ}C$ exhibited the best performance. These characteristics of PVA/PAM membranes are desirable in applications related to the direct methanol fuel cell (DMFC).

Generalized BER Analysis of Arbitrary Rectangular QAM (임의의 사각형 QAM의 일반화된 비트 오율 분석)

  • Yoon Dong-Weon;Cho, Kyong-Kuk;Suh, Ki-Bum
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.10A
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    • pp.962-968
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    • 2002
  • Reliable high-speed data communications over insufficient channel bandwidth is one of the major challenges of harsh wireless environments that push the achievable spectral efficiency far below its theoretical limits. A Quadrature amplitude modulation (QAM) scheme is a userful modulation technique for achieving high data rate transmission without increasing the bandwidth of wireless communication systems. The exact general bit error rate (BER) expression of arbitrary rectangular quadrature amplitude modulation has not yet been derived. In this paper, a generalized closed-form expression for the BER performance of rectangular QAM with Gray code bit mapping is derived and analyzed in the presence of additive white Gaussian noise (AWGN) channel. First we analyze the BER performance of an I-ary PAM scheme. Regular patterns in the k-th bit error probability are observed while developing the EBR expression. From these patterns we provide the exact and general closed-from EBR expression of an I-ary PAM. Then we present a general closed-from expression for BER of an arbitrary IXJ rectangular QAM by considering that this signaling format consists of two PAM scheme, i.e., I-ary and J-ary PAM. A simple approximate BER expression for rectangular QAM is given as well.

High Speed Serial Link Transmitter Using 4-PAM Signaling (4-PAM signaling을 이용한 high speed serial link transmitter)

  • Jeong, Ji-Kyung;Lee, Jeong-Jun;Burm, Jin-Wook;Jeong, Young-Han
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.46 no.11
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    • pp.84-91
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    • 2009
  • A high speed serial link transmitter using multi-level signaling is proposed. To achieve high data rate m high speed serial link, 4-pulse amplitude modulation (PAM) is used. By transmitting 2 bit data in each symbol time, high speed data transmission, two times than binary signaling, is achieved. The transmitter transmits current-mode output instead of voltage-mode output Current-mode output is much faster than voltage-mode output, so higher data transmission is available by increasing switching speed of driver. $2^5-1$ pseudo-random bit sequence (PRBS) generator is contained to perform built-in self test (BIST). The 4-PAM transmitter is designed in Dongbu HiTek $0.18{\mu}m$ CMOS technology and achieves 8 Gb/s, 160 mV of eye height with 1.8 V supply voltage. The transmitter consumes only 98 mW for 8 Gb/s transmission.

AWM Driving Method with Hybrid Current Control for PM-OLED Panel (수동형 OLED를 위한 복합 전류 제어 기능을 갖는 AWM 구동방식)

  • Kim, Seok-Man;Lee, Je-Hoon;Hur, Yeo-Jin;Kim, Yong-Hwan;Cho, Kyoung-Rok
    • The Journal of the Korea Contents Association
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    • v.7 no.1
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    • pp.116-123
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    • 2007
  • This paper proposed a new amplitude width modulation for OLED data driver IC. The data driver controls brightness of OLED by adjusting amplitude and width of the data drive current pulse. There were two conventional methods; pulse amplitude modulation(PAM) and pulse width modulation(PWM). The PWM method suffered from lower light emitting time efficiency at low luminance signal. The PAM method suffered from large chip area using DACs for each column. The proposed method was aiming at accurately controlling of the current level by MSB data and light emitting efficiency by LSB data to improve the inefficiencies of the PAM and a PWM. The proposed AWM driver circuit implemented using $0.35-{\mu}m$ 3-poly 4-metal CMOS high voltage process. The simulation result shows the improvement in the accuracy of the gray level control even though the driver circuit is smaller than the PAM.

Protective Effects of Oleic Acid Against Palmitic Acid-Induced Apoptosis in Pancreatic AR42J Cells and Its Mechanisms

  • Ahn, Joung Hoon;Kim, Min Hye;Kwon, Hyung Joo;Choi, Soo Young;Kwon, Hyeok Yil
    • The Korean Journal of Physiology and Pharmacology
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    • v.17 no.1
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    • pp.43-50
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    • 2013
  • Palmitic acid (PAM), one of the most common saturated fatty acid (SFA) in animals and plants, has been shown to induce apoptosis in exocrine pancreatic AR42J cells. In this study, we investigated cellular mechanisms underlying protective effects of oleic acid (OLA) against the lipotoxic actions of PAM in AR42J cells. Exposure of cells to long-chain SFA induced apoptotic cell death determined by MTT cell viability assay and Hoechst staining. Co-treatment of OLA with PAM markedly protected cells against PAM-induced apoptosis. OLA significantly attenuated the PAM-induced increase in the levels of pro-apoptotic Bak protein, cleaved forms of apoptotic proteins (caspase-3, PARP). On the contrary, OLA restored the decreased levels of anti-apoptotic Bcl-2 family proteins (Bcl-2, Bcl-xL, and Mcl-1) in PAM-treated cells. OLA also induced up-regulation of the mRNA expression of Dgat2 and Cpt1 genes which are involved in triacylglycerol (TAG) synthesis and mitochondrial ${\beta}$-oxidation, respectively. Intracellular TAG accumulation was increased by OLA supplementation in accordance with enhanced expression of Dgat2 gene. These results indicate that restoration of anti-apoptotic/pro-apop-totic protein balance from apoptosis toward cell survival is involved in the cytoprotective effects of OLA against PAM-induced apoptosis in pancreatic AR42J cells. In addition, OLA-induced increase in TAG accumulation and up-regulation of Dgat2 and Cpt1 gene expressions may be possibly associated in part with the ability of OLA to protect cells from deleterious actions of PAM.