• Title/Summary/Keyword: Shaping gain

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High power tunable Ti:sapphire laser with sub-40fs pulsewidth (40펨토초 미만 펄스폭의 고출력 파장가변 티타늄사파이어 레이저)

  • 임용식;노영철;이기주;김대식;장준성
    • Korean Journal of Optics and Photonics
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    • v.10 no.5
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    • pp.430-438
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    • 1999
  • We have utilized soft-aperturing by gain media to develop a high-power tunable Ti:Sapphire laser with sub-40-fs and broad tuning range. The tunable spectral range was only limited by the bandwidth of mirrors. We made use of knife-edge slits near an intra-cavity prism controlled by micro-stepping-motors to tune the center wavelength continuously. The tunability of the center wavelength was ranged from 770 nm to 870 nm, and the measured pulsewidth was sub-40 fs throughout the above spectral range. The shortest pulsewidth was about 17 fs at the center wavelength of 820 nm and the spectral bandwidth was 72 nm. At 5 W pumping power of the Ar-ion laser we obtained average output power of 440 mW~580 mW. For the cw and Kerr-lens mode-lodking conditions, we have evaluated the value of an amplitude modulation to be ${\gamma}=2.5{\times}10^{-8}/W$ from the calculated waists of a Gaussian beam on the Ti:sapphire crystal surface. Using this result we demonstrate that the generation of sub-40-fs Kerr-lens mode-locked pulse can be described by the Ginzberg-Landau model which is a weak pulse shaping model.

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Preliminary Research of CZT Based PET System Development in KAERI

  • Jo, Woo Jin;Jeong, Manhee;Kim, Han Soo;Kim, Sang Yeol;Ha, Jang Ho
    • Journal of Radiation Protection and Research
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    • v.41 no.2
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    • pp.81-86
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    • 2016
  • Background: For positron emission tomography (PET) application, cadmium zinc telluride (CZT) has been investigated by several institutes to replace detectors from a conventional system using photomultipliers or Silicon-photomultipliers (SiPMs). The spatial and energy resolution in using CZT can be superior to current scintillator-based state-of-the-art PET detectors. CZT has been under development for several years at the Korea Atomic Energy Research Institute (KAERI) to provide a high performance gamma ray detection, which needs a single crystallinity, a good uniformity, a high stopping power, and a wide band gap. Materials and Methods: Before applying our own grown CZT detectors in the prototype PET system, we investigated preliminary research with a developed discrete type data acquisition (DAQ) system for coincident events at 128 anode pixels and two common cathodes of two CZT detectors from Redlen. Each detector has a $19.4{\times}19.4{\times}6mm^3$ volume size with a 2.2 mm anode pixel pitch. Discrete amplifiers consist of a preamplifier with a gain of $8mV{\cdot}fC^{-1}$ and noise of 55 equivalent noise charge (ENC), a $CR-RC^4$ shaping amplifier with a $5{\mu}s$ peak time, and an analog-to-digital converter (ADC) driver. The DAQ system has 65 mega-sample per second flash ADC, a self and external trigger, and a USB 3.0 interface. Results and Discussion: Characteristics such as the current-to-voltage curve, energy resolution, and electron mobility life-time products for CZT detectors are investigated. In addition, preliminary results of gamma ray imaging using 511 keV of a $^{22}Na$ gamma ray source were obtained. Conclusion: In this study, the DAQ system with a CZT radiation sensor was successfully developed and a PET image was acquired by two sets of the developed DAQ system.

Design of Cic roll-off Compensation Filter in Digital Receiver For W-CDMA NODE-B (W-CDMA 기지국용 디지털 수신기의 CIC 롤 오프 보상필터 설계)

  • 김성도;최승원
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.12
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    • pp.155-160
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    • 2003
  • Owing to the advances in ADC and DSP technologies, signals in If band, which once had to be processed in analog technology, can new be digitally processed. This is referred to as "Digital IF" or "Digital Radio", which is a preliminary stage of SDR. Applying the digital radio technology to a multi-carrier receiver design, a processing gain is generated through an over-sampling of input data. In the digital receiver, decimation is performed for reducing the computational complexity CIC and half band filter is used together with the decimation as an anti-alising filter. The CIC filter, however, should introduce the roll-off phenomenon in the passband, which causes the receiving performance to be considerably degraded due to the distorted Passband flatness of receiving filter. In this paper, we designed a CIC roll-off compensation filter for W-CDMA digital receiver. The performance of the proposed compensation filter is confirmed through computer simulations in such a way that the BER is minimized by compensating the roll-off characteristics.off characteristics.

A Study on Convolutionally-Coded Overlapped Multicarrier DS-CDMA Systems in a Multipath Fading Channel (다중경로 페이딩 채널에서 콘볼루션 채널코딩을 적용한 중복된 멀티캐리어 DS-CDMA 시스템에 관한 연구)

  • Oh, Jung-Hun;Hwang, Yong-Nam;Youm, Joeng-Won;Kim, Ki-Doo
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.37 no.1
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    • pp.76-87
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    • 2000
  • Multicarrier DS-CDAM is an effective approach to realize wideband CDMA system in a multipath fading channeal. In this paper, we propose a cinvolutionally-coded overlapped multicarrier DS-CDMA system, and show the performance improvement by comparing with conventional multicarrier DS-CDMA system. We consider the case of 50% overlapping with the adjacent subband to utilize the transmission bandwidth more efficiently. In the proposed multicarrier system, each of the rate 1/M convolutionally-encoded symbols is also 1/R repetition coded and transmitted using overlapped multicarriers and we may obtain the coding gain and frequency diversity effect, simultaneously. We also analyze the possibility of reduction in total MUI by considering a raised-cosine wave-shaping filter having a roll-off factor (0< ${\beta}{\le}1$). It will be shown that the proposed system outperforms the multicarrier DS-CDMA system in $^{[3]}$.

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Incorporation of Media in the Activities of Scientific Library of Higher Education Institution

  • Horban, Yurii;Berezhna, Oksana;Bohush, Iryna;Doroshenko, Yevhenii;Kovbel, Viktoriia
    • International Journal of Computer Science & Network Security
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    • v.22 no.4
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    • pp.59-66
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    • 2022
  • Students can successfully connect with one another thanks to the introduction of Web 2.0 and the tools and technology linked with it. The fact that rising digital tools are systematically influencing the education system is not a secret. The purpose of the research article efficiently evaluates the influence of incorporation of media in the activities of the scientific library of the higher education institution. The research Methodology is the Concepts, techniques, and procedures to effectively inculcate primary and secondary data to conduct the research effortlessly. It's worth noting that in this case, quantitative primary research was provided in the form of a survey. The researchers have proposed a survey in order to successfully instil a comprehensive view on the "incorporation of media in the operations of the scientific library of higher education institutions." As a result, fifty-one higher education institution principals were asked to attend this session. This is necessary to understand that they are both well-educated and cognizant of the impact of technology innovation on schooling. As a result, the researchers were able to gain a comprehensive view of this situation thanks to this survey. The results effectively showed that most of the participants believe that social media plays a vital role in shaping up higher education and at the same time they believe that the libraries of famous educational institutions must adapt as per the new educational trend so that teachers and students both can tap into its benefit.The practical significance of the result is manoeuvred by the efficient survey analysis and at the same time, peer-reviewed journals have been employed to put forward authentic information. Therefore, efficient insight regarding this topic has been gathered by the researchers.

MPEG Surround for Multi-Channel Audio Coding-Part 2: Various Modes and Tools (다채널 오디오 코딩을 위한 MPEG Surround-2부: 다양한 모드 및 툴들)

  • Pang, Hee-Suk
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.7
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    • pp.610-617
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    • 2009
  • An overview of various modes and tools of MPEG Surround is provided Because the binaural mode of MPEG Surround supports the virtual 5.1-channel playback based on HRTFs, it can be played via headphones and earphones for portable audio devices. MPEG Surround also supports the enhanced matrix mode which converts stereo signals to 5.1-channel signals without side information, the 3D stereo mode which deals with 3D-coded signals, the low power version which greatly reduces the computational load in the decoding process. Besides, MPEG Surround provides the arbitrary downmix gains (ADGs) tool which is applied to artistic downmix signals, the matrix compatibility tool which is applied to downmix signals by conventional matrix-based methods, the residual coding tool -which can be used at high bit rates, and the GES tool which is applied to specific sound such as applause. The listening test results by various companies and organizations are also presented for important modes and tools.

The Educational Significance of Place Experience through Folklore (설화를 통한 장소 경험의 융합교육적 의의 -청주 지역 전승의 <지네 장터> 설화를 중심으로)

  • Hwang, Yun-jeong;Seo, Myug-hee
    • Journal of Korean Classical Literature and Education
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    • no.34
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    • pp.75-113
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    • 2017
  • The purpose of fusion education is to acquire educational contents efficiently and gain a new worldview. To realize this purpose, I point out that it is urgent to provide common educational content and suggest "place experience" as common content for literature and geography. Local legends present a concrete space and a sharp confrontation with the human world, while shaping the tradition of a place's name. Place experience as common educational content enables a three-dimensional experience of a place that utilizes the characteristics of these local legends. The physical condition, human activity, and implied meaning of a place mediate the student's empirical understanding of folktales. The common area of "place experience" allows us to expect a stereotypical understanding of a learner's place by providing a literary context to learning contents that can flow from the existing geography subject to the simple provision of information. In addition, it facilitates learners' empirical understanding by providing actual and specific objects to learning contents, which can flow abstractly in the existing literature subject. Through this discussion, convergence education demonstrates educational significance by achieving educational efficiency through common educational content and enabling the formation of new thinking.

Chronic pain control in patients with rheumatoid arthritis (만성통증 환자의 통증 조절)

  • Eun, Young
    • Journal of muscle and joint health
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    • v.2 no.1
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    • pp.17-40
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    • 1995
  • Rheumatoid arthritis is the one of the chronic diseases, one of its major symptoms is a chronic pain. Despite developing medical treatment and surgical techniques, it is suggested that to control the pain is the goal of the treatment. But pain is an inner experience and even those closest to the patient cannot truly observe its progress or share in its suffering. The National Academy of Sciences Institute of Medicine's report on Pain and Disability concluded that there is no objective measure of pain-(exactly) no pain thermometer-nor can there ever be one, because the experience of pain is inseparable from personal perception and social influence such as culture. To explore chronic pain experience is to understand the process and property of the patient's perception of pain through the response to pain, the coping with pain, and the adaptation to pain. Therefore a qualitative study was conducted in order to gain an understanding of pain experience of patients with RA in korea. I used naturalistic inquiry as a research methodology, which had 5 axioms, the first is that realities are multiple, constructed, and holistic, the second is that knower and known are interactive, inseparable, the third is only time and context bound working hypotheses(idiographic statements) are possible, the forth is all entities are in a state of mutual simultaneous shaping, so that it is impossible to distinguish causes from effects and the last is that inquiry is value-bound. Purposive sampling was conducted as a sampling. 20 subjects who experienced pain over 10 years, lived in middle-sized city and big city in Korea, and 17 women and 3 men. The subject's age was from 32 to 62 (average 48.8), all were married, living with their spouse and children, except two-one divorced and the other widow before they became ill. I collected data using In depth structured interview. I had interviews two or three times with each subject, and the interviews were conducted at each subject's home. Each interview lasted about two hours an average. A recording was taken with the consent of the subject. I used inductive data analysis-such as unitizing and categorizing. unitizing is a process of coding, whereby raw data are systematically transformed and aggregated into units. Categorizing is a process wherby previously unitized data are organized into categories that provide descriptive or inferential information about the context or setting from which the units were derived. This process is used constant comparative method. The pain controlling process is composed of behavior of pain control. The behaviors of pain control are rearranging of ADL, hiddening role conflict, balancing treatment, and changing social relation. Rearranging of ADL includes diet management, sleep management, and the adjustment of daily life activities. The subjects try to rearrange their daily activities by modified style of motions, rearranging time span & range of activities, using auxillary facilities, and getting help in order to keep on the pace of daily life. Hiddening role conflict means to reduce conflicts between sick role and their role as a family member. In this process, the subjects use two modes, one is to control the pain complaints, and the other is to internalize the value which is to stay home is good for caring her children and being a good mother. To control pain complaints is done by 'enduring', 'understanding' the other family members, or making them undersood in order to reduce pain. Balancing treatment is composed of two aspects. One is to keep the pain within the endurable level, the other is to keep in touch with medical personnel in order to get the information of treatment and emotional support. Changing social relation is made by information seeking and sharing, formation of mutual support relation, and finally simplification of social relationships. The subjects simplify their social relationships by refraining from relations with someone who makes them physically and psychologically strained. In particular the subjects are apt to avoid contact with in-laws, and the change of relation to in-laws results in lessening the family boundary. In the course of this process, they confront the crisis of family confict result in family dissolution. This crisis is related to the threat of self-existence. Findings from this study contribute to understanding the chronic pain experience. To advance this study, we should compare this result with other cases in different cultural contexts. I think to interpret these results, korean cultural background should be considered. Especially the different family concept, more broader family members and kinship network, and the traditional medical knowledge influences patients' behavior.

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