• 대한디지털의료영상학회논문지
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• 제9권2호
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• pp.31-38
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• 2007

To evaluate the accuracy and extent in the localization of cerebral motor coutex activation using a gradient- echo echo planar imaging(GE-EPI) compared to spin-echo echo planar iimaging(SE-EPI) on 3T MR imaging. Functional MR imaging of cerebral motor cortex activation was examined in GE-EPI and SE-EPI in five healthy male volunteers. A right finger movement was accomplished with a paradigm of 6 task and rest, periods and the cross-correlation was used for a statistical mapping algorithm. We evaluated any sorts of differenced of the time seried and the signal intensity changes between the rest and task periods obtained with two technoques. The qualitative analysis was distributed with activation sites of large veins and small veins by using two techniques and was found that both the techniques were clinically uesful for delineating large veins and small veins in fMRL Signal intensity charge of the rest and activation periods provided simmilar activations in both methods(GE-EPI : 0.93$\pm$0.11, SE-EPI : 0.80$\pm$.015) but the signal intensity in GE-EPI(133.95$\pm$15.76) was larger than in SE-EPI(74.5$\pm$18.90). The average SNRs of EPI raw data were higher at SMA in SE-EPI(48.54$\pm$12.37) than GE-EPI(41.4$\pm$12.54) and at M1 in SE-EPI(43.24$\pm$11.77) than GE-EPI(38.27$\pm$6.53). The localization of activation voxels of the GE-EPI showed a larger vein but the SE-EPI generally showed small vein. Then the analysis results of the two techniques were used for a statistacal paired student t-test. SE-EPI was found clinically useful for localizing the cerebral moter cortex cativation on 3.0T, but showed a little different activation patterns comparad to GE-EPI. In conclusion, SE-EPI may be feasible and can detect true cortical activation from capillaries and GE-EPI can obtain the large veins in the motor cortex activation on 3T MR imaging.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.249-249
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• 2013

Surface-enhanced Raman spectroscopy (SERS) is a sensitive approach to detect and to identify a variety of molecules. To enhance the Raman signal, optimization of the gap between nanostructures is quite important. One-dimensional materials such as nanowires, nanotubes, and nanograsses have great potential to be used in SERS due to their unique sizes and shape dependent characteristics. In this study we investigate a simple way to fabricate SERS substrates based on randomly grown copper oxide (CuO) nanowires. CuO nanograss is fabricated on pre-cleaned Cu foils. Cu oxidized in an ammonium ambient solution of 2.5 M NaOH and 0.1 M $(NH_4)_2S_2O_8$ at $4^{\circ}C$ for 10, 30, and 60 minutes. Then, Cu(OH)2 nanostructures are formed and dried at $180^{\circ}C$ for 2 h. With the drying process, the Cu(OH)2 nanostructure is transformed to CuO nanograss by dehydration reaction. CuO nanograss are grown randomly on Cu foil with the average length of 10 ${\mu}m$ and the average diameter of a 100 nm. CuO nanograsses are covered by Ag with various thicknesses from 10 to 30 nm using a thermal evaporator. Then, we immerse uncoated and Ag coated CuO nanowire samples of various oxidation times in a 0.001M methanol-based 4-mercaptopyridine (4-Mpy) in order to evaluate SERS enhancement. Raman shift and SERS enhancement are measured using a Raman spectrometer (Horiba, LabRAM ARAMIS Spectrometer) with the laser wavelength of 532 nm. Raman scattering is believed to be enhanced by the interaction between CuO nanograss and Ag island film. The gaps between Ag covered CuO nanograsses are diverse from <10 nm at the bottom to ~200 nm at the top of nanograsses. SERS signal are improved where the gaps are minimized to near 10s of nanometers. There are many spots that provide sufficiently narrow gap between the structures on randomly grown CuO nanograss surface. Then we may find optimal enhancement of Raman signal using the mapping data of average results. Fabrication of CuO nanograss based on a solution method is relatively simple and fast so this result can potentially provide a path toward cost effective fabrication of SERS substrate for sensing applications.

• Journal of Korean Neurosurgical Society
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• 제67권4호
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• pp.442-450
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• 2024

Objective : Cerebral hyperperfusion syndrome (CHS) manifests as a collection of symptoms brought on by heightened focal cerebral blood flow (CBF), afflicting nearly 30% of patients who have undergone superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis. The aim of this study was to investigate whether the amalgamation of magnetic resonance imaging (MRI) fluid-attenuated inversion recovery (FLAIR) and apparent diffusion coefficient (ADC) imaging via MRI can discern cerebral hyperemia after STA-MCA anastomosis surgery. Methods : A retrospective study was performed of patients who underwent STA-MCA anastomosis due to Moyamoya disease or atherosclerotic steno-occlusive disease. A protocol aimed at preventing CHS was instituted, leveraging the use of MRI FLAIR. Patients underwent MRI diffusion with FLAIR imaging 24 hours after STA-MCA anastomosis. A high signal on FLAIR images signified the presence of hyperemia at the bypass site, triggering a protocol of hyperemia care. All patients underwent hemodynamic evaluations, including perfusion MRI, single-photon emission computed tomography (SPECT), and digital subtraction angiography, both before and after the surgery. If a high signal intensity is observed on MRI FLAIR within 24 hours of the surgery, a repeat MRI is performed to confirm the presence of hyperemia. Patients with confirmed hyperemia are managed according to a protocol aimed at preventing further progression. Results : Out of a total of 162 patients, 24 individuals (comprising 16 women and 8 men) exhibited hyperemia on their MRI FLAIR scans following the procedure. SPECT was conducted on 23 patients, and 11 of them yielded positive results. All 24 patients underwent perfusion MRI, but nine of them showed no significant findings. Among the patients, 10 displayed elevations in both CBF and cerebral blood volume (CBV), three only showed elevation in CBF, and two only showed elevation in CBV. Follow-up MRI FLAIR scans conducted 6 months later on these patients revealed complete normalization of the previously observed high signal intensity, with no evidence of ischemic injury. Conclusion : The study determined that the use of MRI FLAIR and ADC mapping is a competent means of early detection of hyperemia after STA-MCA anastomosis surgery. The protocol established can be adopted by other neurosurgical institutions to enhance patient outcomes and mitigate the hazard of permanent cerebral injury caused by cerebral hyperemia.

• 대한전자공학회논문지SD
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• 제46권8호
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• pp.22-30
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• 2009

네트워크 온 칩 (Network-on-Chip, NoC) 기술은 기존 시스템-온-칩(System-on-Chip, SoC) 설계에서 IP 블록 수 증가와 이에 수반된 상호 연결 네트워크 복잡화 및 데이터 대역폭 제한 등의 문제점을 해결하기 위한 새로운 설계 패러다임이다. 더불어 동작 주파수 증가에 따른 급격한 전력 소모 클럭 신호의 분배와 동기화 문제 역시 중요한 이슈이며, 이에 대한 대안으로 광역적으로는 비동기, 국부적으로는 동기식 (Globally Asynchronous Locally Synchronous, GALS) 인 시스템 설계 방법론이 저전력 기술과 결합되어 에너지 소모를 줄이고 모듈적인 설계를 위해서 고려되어 왔다 GALS 방식의 설계 스타일은 정밀한 시스템 수준 전력 관리를 적용하기 위해 최근 소개되고 있는 전압 주파수 구역 (Voltage-Frequency-Island, VFI) 의 개념과 매우 잘 어울린다. 본 논문에서는 VFI를 적용한 NoC 시스템에서 최적의 전압선택을 통해 에너지 소모를 최소화하는 효율적인 알고리즘을 제시한다. 최적의 코어(또는 처리 소자) 전압과 VFI를 찾기 위해 통신량을 고려한 코어 그래프 분할, 통신-경쟁 시간을 고려한 타일 매핑, 전력 변화량을 고려한 코어의 동적 전압 조절 그리고 효율적인 VFI 병합 및 VFI 동적 전압 재 조절을 포함한다. 본 논문에서 제안한 설계 방법론은 기존 연구결과 대비 평균적으로 10.3%의 에너지 효율 향상이 있다는 것을 실험 결과를 통해 보여준다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.148-153
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• 1999

Baikdu-san was a very active volcano during the Cenozoic era and is believed to be formed in late Cenozoic era. Recently it was also reported that there was a major eruption in or around 1002 A.D. and there are evidences which indicate that it is still an active volcano and a potential volcanic hazard. Remote sensing techniques have been widely used to monitor various natural hazards, including volcanic hazards. However, during an active volcanic eruption, volcanic ash can basically cover the sky and often blocks the solar radiation preventing any use of optical sensors. Synthetic aperture radar(SAR) is an ideal tool to monitor the volcanic activities and lava flows, because the wavelength of the microwave signal is considerably longer that the average volcanic ash particle size. In this study we have utilized several sets of SAR data to evaluate the utility of the space-borne SAR system. The data sets include JERS-1(L-band) SAR, and RADARSAT(C-band) data which included both standard mode and the ScanSAR mode data sets. We also utilized several sets of auxiliary data such as local geological maps and JERS-1 OPS data. The routine preprocessing and image processing steps were applied to these data sets before any attempts of classifying and mapping surface geological features. Although we computed sigma nought ($\sigma$$^{0}$) values far the standard mode RADARSAT data, the utility of sigma nought image was minimal in this study. Application of various types of classification algorithms to identify and map several stages of volcanic flows was not very successful. Although this research is still in progress, the following preliminary conclusions could be made: (1) sigma nought (RADARSAT standard mode data) and DN (JERS-1 SAR and RADARSAT ScanSAR data) have limited usefulness for distinguishing early basalt lava flows from late trachyte flows or later trachyte flows from the old basement granitic rocks around Baikdu-san volcano, (2) surface geological structure features such as several faults and volcanic lava flow channels can easily be identified and mapped, and (3) routine application of unsupervised classification methods cannot be used for mapping any types of surface lava flow patterns.

• Journal of Korean Neurosurgical Society
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• 제61권3호
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• pp.363-375
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• 2018

Intraoperative monitoring (IOM) utilizes electrophysiological techniques as a surrogate test and evaluation of nervous function while a patient is under general anesthesia. They are increasingly used for procedures, both surgical and endovascular, to avoid injury during an operation, examine neurological tissue to guide the surgery, or to test electrophysiological function to allow for more complete resection or corrections. The application of IOM during pediatric brain tumor resections encompasses a unique set of technical issues. First, obtaining stable and reliable responses in children of different ages requires detailed understanding of normal age-adjusted brain-spine development. Neurophysiology, anatomy, and anthropometry of children are different from those of adults. Second, monitoring of the brain may include risk to eloquent functions and cranial nerve functions that are difficult with the usual neurophysiological techniques. Third, interpretation of signal change requires unique sets of normative values specific for children of that age. Fourth, tumor resection involves multiple considerations including defining tumor type, size, location, pathophysiology that might require maximal removal of lesion or minimal intervention. IOM techniques can be divided into monitoring and mapping. Mapping involves identification of specific neural structures to avoid or minimize injury. Monitoring is continuous acquisition of neural signals to determine the integrity of the full longitudinal path of the neural system of interest. Motor evoked potentials and somatosensory evoked potentials are representative methodologies for monitoring. Free-running electromyography is also used to monitor irritation or damage to the motor nerves in the lower motor neuron level : cranial nerves, roots, and peripheral nerves. For the surgery of infratentorial tumors, in addition to free-running electromyography of the bulbar muscles, brainstem auditory evoked potentials or corticobulbar motor evoked potentials could be combined to prevent injury of the cranial nerves or nucleus. IOM for cerebral tumors can adopt direct cortical stimulation or direct subcortical stimulation to map the corticospinal pathways in the vicinity of lesion. IOM is a diagnostic as well as interventional tool for neurosurgery. To prove clinical evidence of it is not simple. Randomized controlled prospective studies may not be possible due to ethical reasons. However, prospective longitudinal studies confirming prognostic value of IOM are available. Furthermore, oncological outcome has also been shown to be superior in some brain tumors, with IOM. New methodologies of IOM are being developed and clinically applied. This review establishes a composite view of techniques used today, noting differences between adult and pediatric monitoring.

• 한국음향학회지
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• 제14권2호
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• pp.101-112
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• 1995

본 논문에서는 패턴 매칭 방법에 근거하여 인식 단위가 음소인 음소 기반 인식 시스템을 구성하였다. 선택한 신경망 구조는 생물학적 신경망인 코호넨(T. Kohonen)의 SOFM(Self-Organizing Feature Map)으로 패턴 매칭 과정 중 클러스터러(clusterer)로 사용하였다. SOFM 신경망은 신호 공간에 대해서 최적의 국소(局所) 해부적 사상(local topographical mapping)에 의한 자기 조직화 과정을 수행하며, 그 결과 인식 문제에 있어서 상당히 높은 정확도를 나타낸다. 따라서 SOFM 신경망은 음소 인식에도 효과적으로 응용될 수 있다. 또한 음소 인식 시스템의 성능 향상을 위해 K-means클러스터링 알고리즘이 결합된 학습 알고리즘을 제안하였다. 제안된 음소 인식 시스템의 성능을 평가하기 위해 먼저, 인식 대상음소는 모음군 17개, 자음의 경우 파열음9개, 마찰음 3개, 파찰음 3개, 유음 및 비음 4개, 음소의 성질이 다른 종성 7개의 음소군으로 모두 43개의 음소를 대상으로 실험하였으며, 각 음소군에 대한 특징 지도를 구성하여 레이블러(labeler)의 기능을 수행하게 하였다. 화자 종속 인식 실험 결과 $87.2\%$의 인식률을 보였으며 제안한 학습법의 빠른 수렴성과 인식률 향상을 확인하였다.

• 한국해양학회지
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• 제22권3호
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• pp.143-152
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• 1987

SMS 960(Seafloor Mapping System) Side Scan Sonar에 자기테이프기록계 (Kennedy 900)를 연결하여 해저면 탐사자료를 수치적으로 처리할 수 있는 시스템을 개발, 이를 제주도 성산포 근해에서 시험적으로 적용하여 그 결과를 검토 하였다. 처리시스템은 주로 VAX 11/780 (4MB)를 사용하여 FORTRAN-77로 작성 되었으며 자료의 변환, 보정, 수치분석 및 도면제작 (cartography)을 주요기능으로 가지고 있다. SMS960에 의해 얻어진 수치자료는 특수한 형태를 가지고 있으므로 독자적으로 제작한 자료선별 계수기(Data Selecting Counter와 개인용 컴퓨터 personar computer을 사용하여 주처리 전산시스템에서 처리할 수 있도록 그 형태를 변환시켰으며, 경사거리(slant range)의 보정과 자료의 질적 개선을 위한 전처리 과 정을 거친 다음, 색상표현 으로 해저면 영상도면을 제작하였다. 후방산란 (backscattering) 음파자료를 통계처리하여 4가지 색상으로 제작된 영상도면을, 해저 퇴적물의 물성분포도와 비교해 본 결과 주로 평균입도와 분급도에 잘 대비되었다. 따라서 Side Scan Sonar에 의한 해저면 후 방상란 음향특성을 적절히 분석하므로 써 해저퇴적물의 퇴적상분포연구에 상당한 응용 효과가 있을 것으로 판단된다.

• Molecules and Cells
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• 제20권3호
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• pp.385-391
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• 2005

As a first step towards identifying genes involving in the signal transduction pathways mediating rice blast resistance, we isolated 3 mutants lines that showed enhanced susceptibility to rice blast KJ105 (91-033) from a T-DNA insertion library of the japonica rice cultivar, Hwayeong. Since none of the susceptible phenotypes co-segregated with the T-DNA insertion we adapted a map-based cloning strategy to isolate the gene(s) responsible for the enhanced susceptibility of the Hwayeong mutants. A genetic mapping population was produced by crossing the resistant wild type Hwayeong with the susceptible cultivar, Nagdong. Chi-square analysis of the $F_2$ segregating population indicated that resistance in Hwayeong was controlled by a single major gene that we tentatively named Pi-hy. Randomly selected susceptible plants in the $F_2$ population were used to build an initial map of Pi-hy. The SSLP marker RM2265 on chromosome 2 was closely linked to resistance. High resolution mapping using 105 $F_2$ plants revealed that the resistance gene was tightly linked, or identical, to Pib, a resistance gene with a nucleotide binding sequence and leucine-rich repeats (NB-LRR) previously isolated. Sequence analysis of the Pib locus amplified from three susceptible mutants revealed lesions within this gene, demonstrating that the Pi-hy gene is Pib. The Pib mutations in 1D-22-10-13, 1D-54-16-8, and 1C-143-16-1 were, respectively, a missense mutation in the conserved NB domain 3, a nonsense mutation in the 5th LRR, and a nonsense mutation in the C terminus following the LRRs that causes a small deletion of the C terminus. These findings provide evidence that NB domain 3 and the C terminus are required for full activity of the plant R gene. They also suggest that alterations of the resistance gene can cause major differences in pathogen specificity by affecting interactions with an avirulence factor.

• 한국농림기상학회지
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• 제14권4호
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• pp.143-154
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• 2012

수자원의 수요 증가와 ENSO (El Ni$\tilde{n}$o/La Ni$\tilde{n}$a Southern Oscillation) 등의 기후변화 현상으로 인한 수자원 공급의 불안정 요소가 제기됨에 따라, 수자원 관리 계획 수립 시 장/단기강우 모의의 중요성이 강조되고 있다. 본 연구에서는 미국 플로리다 템파 지역의 두 개 유역을 대상으로 1986년부터 2008년까지의 MM5 지역기후모델을 이용한 강우모의 결과를 시험지역의 33개 관측자료와 CDF-mapping 기법을 이용하여 통계적으로 보정하였으며 그 결과를 바탕으로 ENSO 패턴에 따른 모델의 성능을 평가하였다. 보정된 MM5일 강우 모의결과는 대체적으로 각 관측소의 월 평균 강우량 (ME: 1.0mm)을 잘 모의하는 것으로 나타났다. 블락-크리깅 기법을 이용하여 추정된 유역 평균 일/월 강우량 또한 관측치를 잘 재현하였다(일 강우 ME: 0.8mm, 월 강우 ME: 7.1mm). 한편, ONI (Oceanic Ni$\tilde{n}$o index)를 이용하여 구분한 ENSO 패턴에 따른 강우 모의치를 분석한 결과, 월별 엘리뇨/라니냐 해에 대한 유역 단위의 강우량 모의 성능이 상이한 것으로 나타났다. 이 원인으로 한정된 모수화 적용 및 모델 경계자료 오차 등을 제시하고 이에 대한 보정 방법개선 등의 추가 연구의 필요성을 지적하였다. 본 연구는 ENSO 패턴을 고려한 월별 기후모델 결과를 활용함에 있어 유의점을 제시하였기에, 우기와 건기에 대한 수자원 관리를 위한 적용 등에 유용하게 활용될 것으로 기대된다.