• 대한수의사회지
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• 제20권8호
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• pp.495-498
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• 1984

• Journal of Korean Neurosurgical Society
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• 제41권2호
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• pp.95-99
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• 2007

Objective : The purpose of this reports is to describe the influence of continuous external ventricular drainage [EVD] on delayed ischemic neurologic deficit [DIND] after early surgery in ruptured aneurysmal patients. Methods : The authors reviewed 229 patients with aneurysmal subarachnoid hemorrhage [SAH] who had been treated with clipping at a single institution between 1998 and 2004. Of these, 121 patients underwent continuous EVD [Group A] postoperatively, whereas 108 patients did not [Group B]. EVD was performed at ipsilateral Kocher's point and maintained 2 to 14 days postoperatively. Results : DIND occurred in 15.7% [19 cases] of patients in Group A, 25% [27 cases] from Group B [P value=0.112]. Compared with Group A, Group B was more likely to suffer acute symptom of DIND and showed poor response to 3- H therapy. Major symptoms of DIND in Group A were mild confusion [36.8%] and mild deterioration of mental state [26.3%], contrary to weakness of extremities [59.2%] in Group B. At discharge, Glasgow Outcome Scales [GOS] of Group A were : good recovery [63.2%], moderately disabled [21%], severely disabled [10.5%], dead [5.3%] and Group B : good recovery [48.1%], moderately disabled [37%], severely disabled [14.8%] and dead [0%]. Of 121 patients from group A, 35 patients [28.9%] suffered ventriculitis. Conclusion : Continuous EVD after aneurysmal clipping in patients with SAH reduced the risk of DIND and its sequelae, relieved its symptoms, and improved the outcome.

• 대한안전경영과학회지
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• 제13권1호
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• pp.195-202
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• 2011

The study interprets each of three classification models based on Bath-Tub Failure Rate (BTFR), Extreme Value Distribution (EVD) and Conjugate Bayesian Distribution (CBD). The classification model based on BTFR is analyzed by three failure patterns of decreasing, constant, or increasing which utilize systematic management strategies for reliability of time. Distribution model based on BTFR is identified using individual factors for each of three corresponding cases. First, in case of using shape parameter, the distribution based on BTFR is analyzed with a factor of component or part number. In case of using scale parameter, the distribution model based on BTFR is analyzed with a factor of time precision. Meanwhile, in case of using location parameter, the distribution model based on BTFR is analyzed with a factor of guarantee time. The classification model based on EVD is assorted into long-tailed distribution, medium-tailed distribution, and short-tailed distribution by the length of right-tail in distribution, and depended on asymptotic reliability property which signifies skewness and kurtosis of distribution curve. Furthermore, the classification model based on CBD is relied upon conjugate distribution relations between prior function, likelihood function and posterior function for dimension reduction and easy tractability under the occasion of Bayesian posterior updating.

• 한국세라믹학회지
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• 제33권3호
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• pp.355-361
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• 1996

Yttria stabilized zirconia (YSZ) thin films were prepared by the electrochemical vapor deposition (EVD) method on the porous Al2O3 substrates. Y2O3 mol% of thin film was linearly increased with yttrium mole fraction of vapor phase. As yttrium mole fraction(Zyc13=0.18) increased dense and faceted thin films were enhanced. However as the yttrium mole fraction (Zyc13=0.04) decreased porous thin films with monoclinnic phase prevailed. With increasing pressure difference of substrate sides penetration depth decreased porosity and amount of monoclinic phase in the films increased.

• 한국세라믹학회지
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• 제31권5호
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• pp.477-484
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• 1994

The yttria stabilized zirconia(YSZ) thin films for solid oxide fuel cell (SOFC) were fabricated by an electrochemical vapor deposition(EVD) technique using YCl3+ZrCl4+H2O gas system. The YSZ films were deposited under reduced pressure at the temperature of 1000~120$0^{\circ}C$ on the porous alumina substrates. The deposition rate, chemical composition and growth morphology were investigated by SEM, XRD, EDS. The growth rates of the films obeyed a parabolic rate law, representing that the growing process is controlled by an electrochemical transport through the YSZ film. The Y2O3 content of the films was about 10 mol%, equal to the composition of metal chloride reactant gases, approximately. The YSZ films were highly dense, the growing features showed columnar structure and surface morphologies were changed with the EVD conditions.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2012년도 하계학술대회
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• pp.176-177
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• 2012

사람의 음성을 압축하는 방법으로 Code Excited Linear Prediction (CELP) 코더가 주로 사용되어 왔다. CELP 코더의 수신단에서는 양자화 된 여기신호를 LPC 필터로 합성하여 신호를 복원한다. LPC 합성필터의 영향으로 양자화 된 여기신호의 보로노이 셀 모양이 변형되는 문제점이 있기 때문에 이런 문제점을 해결하기 위해서 Karhunen-Loeve-Transform based Classify vector Quantization (KLT-CVQ) 코더가 제안되었다. 기존 KLT-CVQ 코더는 KLT 변환과 class 선택을 위해서 Eigen Value Decomposition (EVD)을 이용해서 eigen vector와 eigen value를 계산한다. 본 논문에서는 EVD 대신에 UTV Decomposition (UTVD)을 이용하여 KLT-CVQ의 계산량 문제점을 개선하는 방법을 제안한다.

• Journal of Korean Neurosurgical Society
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• 제50권4호
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• pp.317-321
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• 2011

Objective : External ventricular drain (EVD) is commonly performed with a freehand technique using surface anatomical landmarks at two different cranial sites, Kocher's point and the forehead. The aim of this study was to evaluate and compare the accuracy and safety of these percutaneous ventriculostomies. Methods : A retrospectively review of medical records and head computed tomography scans were examined in 227 patients who underwent 250 freehand pass ventriculostomy catheter placements using two different methods at two institutions, between 2003 and 2009. Eighty-one patients underwent 101 ventriculostomies using Kocher's point (group 1), whereas 146 patients underwent 149 forehead ventriculostomies (group 2). Results : In group 1, the catheter tip was optimally placed in either the ipsilateral frontal horn or the third ventricle, through the foramen of Monro (grade 1) in 82 (81.1%) procedures, in the contralateral lateral ventricle (grade 2) in 4 (3.9%), and into eloquent structures or non-target cerebrospinal space (grade 3) in 15 (14.8%). Intracerebral hemorrhage (ICH) >1 mL developed in 5 (5.0%) procedures. Significantly higher incidences of optimal catheter placements were observed in group 2. ICH>1 mL developed in 11 (7.4 %) procedures in group 2, showing no significant difference between groups. In addition, the mean interval from the EVD to ventriculoperitoneal shunt was shorter in group 2 than in group 1, and the incidence of EVD-related infection was decreased in group 2. Conclusion : Accurate and safe ventriculostomies were achieved using both cranial sites, Kocher's point and the forehead. However, the forehead ventriculostomies provided more accurate ventricular punctures.

• 한국통신학회논문지
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• 제31권12C호
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• pp.1257-1264
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• 2006

반송파 주파수 옵셋은 OFDM(Orthogonal Frequency Division Multiplexing) 신호의 부채널간 간섭(ICI)을 유발하며, 수신 신호의 진폭과 위상을 왜곡시켜 전체적인 시스템 성능에 심각한 영향을 미친다. 본 논문에서는 OFDM 시스템에서 주파수 옵셋을 추정하는 새로운 기법을 제한한다. 이 기법은 주파수 옵셋으로 인해 위상이 회전 되어 왜곡된 OFDM 심볼의 CP와 유효 OFDM 심볼에 대해 통계적 독립 성분 분석(ICA - Independent Component Analysis)을 EVD(Eigenvalue Decomposition), 회전 페이저, 그리고 $4^{th}-cumulants$를 이용하여 시간영역에서 추정하여 보상하는 기법이다. 어떤 훈련 심볼열이나 파일럿 심볼을 필요하지 않기 때문에 대역폭 효율의 저하가 없다. 모의실험 결과, 제안된 CP-ICA 기법이 주파수 옵셋의 범위가 $0.0<\varepsilon<1.0$에서 기존의 제안된 주파수 옵셋 추정기보다 매우 좋은 BER 성능 결과를 보여준다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.134-134
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• 2012

We investigated the interface of poly (3-hexylthiophene) (P3HT) and C61-butyric acid methylester (PCBM) by using photoelectron spectroscopy (PES). These are the most widely used materials for bulk heterojunction (BHJ) organic solar cells due to their high efficiency. Study of the BHJ interfaces is difficult because the organic films are typically prepared by spin coating in ambient conditions. This is incompatible with the interface electronic structure probes such as PES, which requires ultrahigh vacuum conditions. Study of interface requires gradual deposition of thin films that is also incompatible with the spin coating process. In this work, we used electrospray vacuum deposition (EVD) technique to deposit P3HT and PCBM in high vacuum conditions. EVD allows us to form polymer thin films onto ITO substrate in a step-wise manner directly from solutions and to use PES without exposing the sample to the ambient condition. Although the morphology of the EVD deposited P3HT films observed by optical and atomic force microscopes is quite different from that of the spin coated ones, the valence region spectra were similar. PCBM was deposited on the P3HT film in a similar manner and the energy level alignment between these two materials was studied. We discuss the relation between Voc of P3HT:PCBM solar cell and HOMO-LUMO energy offset obtained in this study.

• Journal of Korean Neurosurgical Society
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• 제30권sup1호
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• pp.99-107
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• 2001

Objective : Hydrocephalus and vasospasm are the common complications following subarachnoid hemorrhage (SAH). In spite of development of perioperative management and operative technique, hydrocephalus cause neurological deficit and poor prognosis. Usually CSF drainage procedure(external ventricular drainage(EVD) or shunt) is needed in hydrocephalus following SAH. The aim of this study was to investigate whether the need for shunting and the outcome after shunting in hydrocephaus following SAH can be related to the duration, daily and total amount of cerebrospinal fluid(CSF) drainage at EVD. Material and Method : IVH is one of several factors which cause hydrocephalus. In this retrospective study, firstly we investigated the incidence of IVH in total cases and frequency of IVH according to aneurysmal site and then prognosis of IVH following SAH. Among 629 patients with SAH, hydrocephalus was diagnosed by CT scan and symptoms. And then those 102 hydrocephalus following SAH were divided into two groups which were hydrocephalus with IVH group and without IVH group. In these two groups, we investigated and compared the incidence of hydrocephalus in all case, frequency of hydrocephalus according to aneurysmal site, the outcome according to H-H grade on admission and the need rate of shunt, etc. Of those hydrocephalus, 100 EVD procedures were done. The duration, daily and total amount of CSF drainage at EVD were investigated. Fifty cases expired during EVD was excluded. We analyzed whether the need rate of shunt and the final outcome after shunting can be related to IVH, the duration and daily and total amount of CSF drainage. Result : The incidence of hydrocephalus following SAH was 20%(with IVH group ; 64%, without IVH group ; 11%). As H-H grade on admission was better, the outcome of hydrocephalus was also better. The mortality rate of hydrocephalus with IVH was 64% which was higher than 40% that of hydrocephalus without IVH. The need rate of shunt in all cases of hydrocephalus following SAH was 20%, but those with IVH group excluding expired patients before shunt was 40%. This was very similar to 41% of the need rate of shunt in hydrocephalus without IVH. The total amount of CSF drainage was statistically related to the need rate of shunt(total amount : need rate of shunt/<1000cc : 15%, 1000-2000cc : 40%, >2000cc : 50%). The duration and daily amount of CSF drainage were not statistically related to the need rate of shunt, but as daily amount of CSF drainage was more and duration was longer, the need rate of shunt was increased(daily amount : need rate of shunt /<100cc : 16%, 100-200cc : 25%, >200cc : 40%//duration : need rate of shunt/<1week : 8%, 1-2weeks : 30%, >2weeks : 47%), and also the final outcome after shunting was poor. Especially the total amount of CSF drainage was significant related to the final outcome after shunting(total amount : GOS/<1000cc : I&II(3/4), 1000-2000cc : II(2/4), III(2/4), >2000cc : III&IV(6/7)). Conclusion : This study revealed that the incidence and mortality rate of hydrocephalus following SAH were influenced by IVH. So SAH associated IVH has the higher incidence of hydrocephalus and poor outcome. As the CSF drainage amount was more and duration of drainage was longer, the need rate of shunt was increased and the final outcome after shunting was poor. Especially the total amount of CSF drainage were strongly related to the need rate of shunt and the outcome after shunting.