• Title/Summary/Keyword: clipping

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The Effect of Clipping on the Spectrum and BER of IFDMA Signal with Pulse Shaping (파형정형된 IFDMA 신호에서 클리핑이 스펙트럼과 BER에 미치는 영향)

  • Park, Seung-Yong;Kim, Jeong-Goo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.11C
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    • pp.1106-1112
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    • 2009
  • The SC-FDMA(single carrier-frequency division multiple access) was recently adopted as the uplink multiple access scheme from 3GPP LTE(3rd Generation Partnership Project Long Tenn Evolution) due to its low PAPR (Peak-to-averaged power ratio). The bandwidth of IFDMA(interleaved FDMA), one of the sub-carrier mapping methods of SC-FDMA, gets narrower as the roll-off factor of RRC(root raised cosine) filter decreases from 1 to 0, whereas its PAPR can increase significantly. In practice, to increase the power efficiency of an amplifier, signals with high PAPR undergo the process of clipping. Clipping of signals may cause regeneration of high-frequency components as well as distortion of signals. The current paper deals with the effect of clipping on the spectrum and BER of IFDMA signals with RRC filters.

Postoperative Clipping Status after a Pterional versus Interhemispheric Approach for High-Positioned Anterior Communicating Artery Aneurysms

  • Kim, Myungsoo;Kim, Byoung-Joon;Son, Wonsoo;Park, Jaechan
    • Journal of Korean Neurosurgical Society
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    • v.64 no.4
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    • pp.524-533
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    • 2021
  • Objective : When treating high-positioned anterior communicating artery (ACoA) aneurysms, pterional-transsylvian and interhemispheric approaches are both viable options, yet comparative studies of these two surgical approaches are rare. Accordingly, this retrospective study investigated the surgical results of both approaches. Methods : Twenty-four patients underwent a pterional approach (n=11) or interhemispheric approach (n=13), including a unilateral low anterior interhemispheric approach or bifrontal interhemispheric approach, for high-positioned ACoA aneurysms with an aneurysm dome height >15 mm and aneurysm neck height >10 mm both measured from the level of the anterior clinoid process. The clinical and radiological data were reviewed to investigate the surgical results and risk factors of incomplete clipping. Results : The pterional patient group showed a significantly higher incidence of incomplete clipping than the interhemispheric patient group (p=0.031). Four patients (36.4%) who underwent a pterional approach showed a postclipping aneurysm remnant, whereas all the patients who experienced an interhemispheric approach showed complete clipping. In one case, the aneurysm remnant was obliterated by coiling, while follow-up of the other three cases showed the remnants remained limited to the aneurysm base. A multivariate analysis revealed that a pterional approach for a large aneurysm with a diameter >8 mm presented a statistically significant risk factor for incomplete clipping. Conclusion : For high-positioned ACoA aneurysms with a dome height >15 mm and neck height >10 mm above the level of the anterior clinoid process, a large aneurysm with a diameter >8 mm can be clipped more completely via an interhemispheric approach than via a pterional approach.

A Three-year Study on the Leaf and Soil Nitrogen Contents Influenced by Irrigation Frequency, Clipping Return or Removal and Nitrogen Rate in a Creeping Bentgrass Fairway (크리핑 벤트그라스 훼어웨이에서 관수회수.예지물과 질소시비수준이 엽조직 및 토양 질소함유량에 미치는 효과)

  • 김경남;로버트쉬어만
    • Asian Journal of Turfgrass Science
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    • v.11 no.2
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    • pp.105-115
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    • 1997
  • Responses of 'Penncross' creeping bentgrass turf to various fairway cultural practices are not well-established or supported by research results. This study was initiated to evaluate the effects of irrigation frequency, clipping return or removal, and nitrogen rate on leaf and soil nitrogen con-tent in the 'Penncross' creeping bentgrass (Agrostis palustris Huds.) turf. A 'Penncross' creeping bentgrass turf was established in 1988 on a Sharpsburg silty-clay loam (Typic Argiudoll). The experiment was conducted from 1989 to 1991 under nontraffic conditions. A split-split-plot experimental design was used. Daily or biweekly irrigation, clipping return or removal, and 5, 15, or 25 g N $m-^2$ $yr-^1$ were the main-, sub-, and sub-sub-plot treatments, respectively. Treatments were replicated 3 times in a randomized complete block design. The turf was mowed 4 times weekly at a l3 mm height of cut. Leaf tissue nitrogen content was analyzed twice in 1989 and three times in both 1990 and 1991. Leaf samples were collected from turfgrass plants in the treatment plots, dried immediately at 70˚C for 48 hours, and evaluated for total-N content, using the Kjeldahl method. Concurrently, six soil cores (18mm diam. by 200 mm depth) were collected, air dried, and analyzed for total-N content. Nitrogen analysis on the soil and leaf samples were made in the Soil and Plant Analyical Laboratory, at the University of Nebraska, Lincoln, USA. Data were analyzed as a split-split-plot with analysis of variance (ANOVA), using the General Linear Model procedures of the Statistical Analysis System. The nitrogen content of the leaf tissue is variable in creeping bentgrass fairway turf with clip-ping recycles, nitrogen application rate and time after establishment. Leaf tissue nitrogen content increased with clipping return and nitrogen rate. Plots treated with clipping return had 8% and 5% more nitrogen content in the leaf tissue in 1989 and 1990, respectively, as compared to plots treated with clipping removal. Plots applied with high-N level (25g N $m-^2$ $yr-^1$)had 10%, 17%, and 13% more nitrogen content in leaf tissue in 1989, 1990, and 1991, respectively, when compared with plots applied with low-N level (5g N $m-^2$ $yr-^1$). Overall observations during the study indicated that leaf tissue nitrogen content increased at any nitrogen rate with time after establishment. At the low-N level treatment (5g N $m-^2$ $yr-^1$ ), plots sampled in 1991 had 15% more leaf nitrogen content, as compared to plots sampled in 1989. Similar responses were also found from the high-N level treatment (25g N $m-^2$ $yr-^1$ ).Plots analyzed in 1991 were 18% higher than that of plots analyzed in 1989. No significant treatment effects were observed for soil nitrogen content over the first 3 years after establishment. Strategic management application is necessary for the golf course turf, depending on whether clippings return or not. Different approaches should be addressed to turf fertilization program from a standpoint of clipping recycles. It is recommended that regular analysis of the soil and leaf tissue of golf course turf must be made and fertilization program should be developed through the interpretation of its analytic data result. In golf courses where clippings are recycled, the fertilization program need to be adjusted, being 20% to 30% less nitrogen input over the clipping-removed areas. Key words: Agrostis palustris Huds., 'Penncross' creeping bentgrass fairway, Irrigation frequency, Clipping return, Nitrogen rate, Leaf nitrogen content, Soil nitrogen content.

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Emergency In Situ Bypass during Middle Cerebral Artery Aneurysm Surgery : Middle Cerebral Artery-Superficial Temporal Artery Interposition Graft-Middle Cerebral Artery Anastomosis

  • Jung, Jong-Myung;Oh, Chang-Wan;Song, Kyung-Sun;Bang, Jae-Seung
    • Journal of Korean Neurosurgical Society
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    • v.51 no.5
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    • pp.292-295
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    • 2012
  • Many reports have been published on complications related to middle cerebral artery (MCA) aneurysm surgical clipping procedures. We report an emergency intracranial in situ bypass surgery case which was performed as a rescue procedure after aneurysmal neck laceration during clipping of an MCA large aneurysm. In this case, we performed in situ M3-superficial temporal artery (STA) interposition graft-M3 bypass procedure. If a STA-MCA anastomosis is not available under MCA flow obstruction, we can consider an emergency in situ MCA-MCA bypass procedure with or without an STA interposition graft.

A Clipping-free Multi-bit $\Sigma\Delta$ Modulator with Digital-controlled Analog Integrators (디지털 제어 적분형의 차단 현상이 없는 A/D 다중 비트 $\Sigma\Delta$ 변조기)

  • 이동연;김원찬
    • Journal of the Korean Institute of Telematics and Electronics C
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    • v.34C no.4
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    • pp.26-35
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    • 1997
  • This paper proposes a multi-bit $\Sigma\Delta$ modulator arcitecture which eliminates signal clipping problem. To avoid signal clipping, the output values of intgrators are monitored and modified by a reference value. This oepration is recorded as a digital code to restore actual signal value. Due to the digital code, the substraction of feedback value from the multi-bit quantizer can be calculated by a digital adder and this simplifies dAC operation making the accurate DAC of conventional multi-bit $\Sigma\Delta$ modulator scheme unnecessary. These features make N-th modulator can be implemented by sharing an integrator among N stages to decrease the required chip area. As an experimental example, a 4th order .sum..DELTA. modulator with oversampling ratio of 64 was simulated to show over 130 DB SNR at rail-to-rail input sinusoidal signal.

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Contralateral Intraparenchymal Hemorrhage Following Aneurysmal Clipping

  • Kim, Jae-Hoon;Yi, Hyeong-Joong
    • Journal of Korean Neurosurgical Society
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    • v.43 no.3
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    • pp.162-164
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    • 2008
  • Post-clipping intraparenchymal hemorrhage of the contralateral hemisphere is a very unusual phenomenon in a patient with aneurysmal subarachnoid hemorrhage, unless there is an underlying condition. We report a complicated case of 47-year-old man, who underwent uneventful clipping of ruptured aneurysm and experienced vasospasm two weeks later. Vasospasm was treated by intra-arterial nimodipine and systemic hyperdynamic therapy. One week thereafter, he became unconscious due to intraparenchymal hemorrhage on the anterior border-zone of contalateral hemisphere, but intraoperative and pathologic findings failed to disclose any vascular anomaly. We suggest that the anti-spastic regimens cause local hemodynamic redistribution through the vasodilatory effect and in turn, resulted in such an unexpected bleeding.

Postoperative Vasospasm in Unruptured Intracranial Aneurysm

  • Lee, Suk-In;Park, Cheol-Wan;Hong, Won-Jin;Park, Chan-Woo
    • Journal of Korean Neurosurgical Society
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    • v.40 no.2
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    • pp.131-134
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    • 2006
  • The cerebral vasospasm after clipping surgery of unruptured aneurysm is uncommon. A 44-year-old man with unruptured left middle cerebral artery[MCA] aneurysm had clipping surgery. From the third postoperative day, he presented with drowsy mentality, dysphasia and right hemiparesis. Computed tomographic scans showed low density area in frontotemporal lobe and midline shift. Transfemoral cerebral angiography revealed severe vasospasm in supraclinoid internal carotid artery, anterior cerebral artery, and MCA on the operative side. We performed left frontotemporoparietal craniectomy and hypertensive-hypervolemic therapy. He recovered without neurological deficits but for dysphasia. Neurosurgeon should be alert to the possibility of vasospasm after clipping surgery even in case of unruptured cerebral aneurysm.

Nitrogen Utility during the Population Development with Different Clipping Treatments on Italian Rye Grass Field (Italian Rye Grass 초지군락의 청예처리빈도에 따른 생산성과 질소이용성)

  • 송승달
    • Journal of Plant Biology
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    • v.22 no.3
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    • pp.63-69
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    • 1979
  • The plant growth and net production, the nitrogen uptake and recycling, the nitrogen mobility and allocation to each organ, and the nitrogen utility from the Italian rye grass field during the population development were analyzed in comparison with different clipping treatments. The maximum dry matter standing crop and nitrogen quantity of harvest increased significantly, however, the annual amounts of dry matter and nitrogen assimilation showed little variations with increasing clipping frequencies. Plants treated with frequent clippings allocated relatively more nitrogen to leaves and less to roots during the experimental period. The amount of recycling of nitrogen decreased considerably due to frequent clippings. The annual averages of nitrogen utility indices changed in inverse relation to the nitrogen availability; such as 63, 58, 44 and 35 for C, A, M and J plots, respectively.

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Fast Time-Scale Modification of Speech Using Nonlinear Clipping Methods

  • Jung, Ho-Young;Kim, Hyung-Soon;Lee, Sung-Joo
    • MALSORI
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    • no.59
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    • pp.69-87
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    • 2006
  • Among the conventional time-scale modification (TSM) methods, the synchronized overlap and add (SOLA) method is widely used due to its good performance relative to computational complexity But the SOLA method remains complex due to its synchronization procedure using the normalized cross-correlation function. In this paper, we introduce a computationally efficient SOLA method utilizing 3 level center clipping method, as well as zero-crossing and level-crossing information. The result of subjective preference test indicates that the proposed method can reduce the computational complexity by over 80% compared with the conventional SOLA method without serious degradation of synthesized speech quality.

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On a Waveform Coding Technique Using Pitch Searching and 3-Level Clipping (피치검색기법과 3-Level Clipping을 이용한 음성 파형부호화법에 관한 연구)

  • 김규홍
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1998.08a
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    • pp.127-130
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    • 1998
  • 피치검색과 3-level clipping을 이용한 새로운 파형부호화법을 제안하고자 한다. 제안한 방법에서는 우선 피치를 검출하여 기준피치파형과 인근피치파형을 검색한다. 그 후 유사도 측정시 기준피치파형과 인근 피치파형에 대해 3-level clippng을 수행한다. 클리핑된 기준피치파형가 인근피치파형간의 유사도를 측정하여 유사성이 크다면 피치정보와 에너지 정보만을 전송하거나 저장하여 압축을 하고, 유사성이 적다면 인근피치파형을 압축을 하지 않고 저장한다. 그 후에 저장된 ?ㅇ을 기준 피치파형으로 재정의 하여 다시 반복적으로 압축을 수행한다. 압축된 음성신호를 다시 복원할 때에는 수신 또는 저장된 음성신호를 이용하여 PSOLA 방식으로 합성을 수행한다. 평균압축율이 약 65%일 경우에도, MOS 값이 4이상을 유지하였다.

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