• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.328-331
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• 2008

In order to see the detailed characteristics of model scramjet engine, numerical analysis was performed and compared to the ground test results done by KARI and UQ. Pressure distribution predicted by numerical analysis showed good agreements with test results. Static temperature and pressure distribution explained the mechanisms of cavity flame holder and W-shape cowl which have showed enhancing effects on the supersonic combustion.

• Journal of Gastric Cancer
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• v.9 no.3
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• pp.128-135
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• 2009

Purpose: The aim of this study was to compare synchronous and metachronous hepatic metastases in patients with gastric cancer to determine clinicopathologic features and differences in prognosis as a function of the timing of the metastasis and the treatment modality rendered. Materials and Methods: Sixty-seven patients who were diagnosed with gastric cancer metastatic to the liver and treated at the Hanyang University Hospital between June 1992 and December 2006 were retrospectively analyzed to study the pertinent clinicopathologic features and effect of treatment methods. Results: There was a significant difference with respect to lymphatic (P=0.041) and vascular invasion (P=0.036) in comparing the clinicopathologic features between the patients with synchronous and metachronous hepatic metastases. The 1-year survival rate and median survival time of patients with gastric cancer and liver metastases were 38.9% and 9.2 months in the entire patient cohort, 30.9% and 9.2 months in the synchronous group, and 44.5% and 9.7 months in the metachronus group, respectively (P=0.436). The group of patients undergoing local treatment (such as surgery and radiologic intervention) followed by systemic chemotherapy, the group of patients receiving systemic chemotherapy only, and the untreated group of patients were compared, and there was no difference between the synchronous and metachronous groups. The synchronous and metachronous groups had high survival rates with local treatment. Conclusion: In patients with gastric cancer and liver metastases, there was no difference in prognosis based on the timing of the hepatic metastases. Independent of the timing of hepatic metastasis, aggressive treatment, such as surgery and radiologic intervention, may help improve the prognosis.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.65-71
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• 2003

To maximize the storage density in a localized hologram recording method, each hologram should be recorded as close as possible to its neighboring holograms. In this case, the reference beams used to record two adjacent holograms may overlap in spatial multiplexing. Through simulations and experiments, we show that there exists an optimal reference beam size to minimize the overlap for a given shifting distance of the reference beams in spatial multiplexing. Thus the advantages of the localized hologram recording method can be minimally sacrificed while the storage density is increased.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.25-25
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• 2017

국지 혹은 지역적인 기후의 특성은 지구규모 또는 종관규모에서의 온실가스 증가로 인한 온난화와 동시에 도시화 (urbanization)에 따른 열섬 현상 (heat island effect)을 포함한 인위적인 요소들이 복합적으로 작용하여 나타날 수 있다. 도시화에 따른 지면피복의 변화는 관측된 온난화 신호에 일정부분 기여하며, 도시 지역은 농촌 및 산림 지역과 비교하여 수문 및 기후학적 측면에서 지역 내 에너지수지 및 물수지의 특성이 상이하기 때문에, 지구온난화에 의한 전 지구적 현상과 도시화에 의한 국소적 현상을 구분하여 파악하는 것은 중요하다. 또한 향후 도시/비도시에 따른 도시화 편향 영향으로 인한 기후변화 예측의 편이를 분석하는데 필수적으로 요구된다. 본 연구에서는 급격한 도시화로 인한 인위적인 기후변화 (anthropogenic climate change)와 종관규모에서의 자연적 기후변화 (natural climate change or climate change)에 기인한 부분을 정량적으로 구분하고자 한다. 이를 위해 도시화의 정도가 서로 다른 도시 지역 및 농촌, 산림 지역을 선정하여 최근 50년간 (1966~2015년) 기상청 관측소의 기상자료와 각 관측지점별 인구수 및 인구증가/감소 추세를 비교함으로써 도시화율의 변화가 기상요소에 미치는 영향의 지역별 차이를 정량적으로 분석하였다.

• Journal of Advanced Navigation Technology
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• v.28 no.1
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• pp.129-135
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• 2024

In this paper, an analytical approach for the design and analysis of an aperiodic electromagnetic bandgap (EBG)-based power distribution network (PDN) in high-speed integrated-circuit (IC) packages and printed circuit boards (PCBs) is proposed. Aperiodic EBG is an effective method to solve the noise problem of high-speed IC packages and PCBs. However, its analysis becomes challenging due to increased computation time. To overcome the problem, the proposed analytical method entails deriving impedance parameters for EBG island and the overall PDN, which includes locally placed EBG structures. To validate the proposed method, a test vehicle is fabricated, demonstrating good agreement with the measurements. Significantly, the proposed analytical method reduces computation time by 99.7 %compared to the full-wave simulation method.

• The Transactions of the Korea Information Processing Society
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• v.7 no.1
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• pp.286-295
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• 2000

We present a novel statistically adaptive method using the Minimum Description Length(MDL) principle for unsupervised segmentation of magnetic resonance(MR) images. In the method, Markov random filed(MRF) modeling of tissue region accounts for random noise. Intensity measurements on the local region defined by a window are modeled by a finite Gaussian mixture, which accounts for image inhomogeneities. The segmentation algorithm is based on an iterative conditional modes(ICM) algorithm, approximately finds maximum ${\alpha}$ posteriori(MAP) estimation, and estimates model parameters on the local region. The size of the window for parameter estimation and segmentation is estimated from the image using the MDL principle. In the experiments, the technique well reflected image characteristic of the local region and showed better results than conventional methods in segmentation of MR images with inhomogeneities, especially.

• Korean Journal of Environment and Ecology
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• v.7 no.2
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• pp.104-111
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• 1994

The marsh vegetation in the vicinity of Tumunsan, Tokyusan National Park, Chollapuk-do, Korea was analysed in order to find out the vegetational characteristics. The total number of vascular plants surveyed were summarized as 39 familieis, 77 genera, 74 species, 18 varieties and 1 form. The ten species such as Juncus effusus var. decipiens, Carex leiorhyncha, Lysimachia vulgaris var. davurica, Sirpus triqueter, Scirpus karuizawensis, Caltha palustris var. membranacea, Carex doniana, Carex humilis, Vicia venosa, and Disporum smilacinum showed the Importance Value more than 10 % in herbaceous marsh vegetation. The species such as Heloniopsis orientalis, Astilbe chinensis var. davidii, Trignotis peduncularis, Lycopus ramosissimus var. japonicus, Iris nertschinskia and Hosta capitata were distributed at very limited or wide spread localities in the marsh. The marsh vegetation in this area is one of the rare and very distinct natural resources in Tokyusan National Park and the proper Action Plan of Management is strongly needed because the projected developing works in this site will act seriously in marsh vegetational changes in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5930-5938
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• 2013

The sigmoid functionally graded mateiral(S-FGM) theory is reformulated using the nonlocal elatictiry of Erigen. The equation of equilibrium of the nonlocal elasticity are derived. This theory has ability to capture the both small scale effects and sigmoid function in terms of the volume fraction of the constituents for material properties through the plate thickness. Navier's method has been used to solve the governing equations for all edges simply supported boundary conditions. Numerical solutions of biaxial buckling of nano-scale plates are presented using this theory to illustrate the effects of nonlocal theory and power law index of sigmoid function on buckling load. The relations between nonlocal and local theories are discussed by numerical results. Further, effects of (i) power law index, (ii) length, (iii) nonlocal parameter, (iv) aspect ratio and (v) mode number on nondimensional biaxial buckling load are studied. To validate the present solutions, the reference solutions are discussed.

• Journal of Oral Medicine and Pain
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• v.37 no.1
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• pp.1-7
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• 2012

Burning mouth syndrome(BMS) refers to a chronic orofacial pain disorder usually unaccompanied by mucosal lesions or other clinical signs. Tongue(anterior and lateral border) is found to be the most common site for the burning sensations in the oral cavity, and various oral sites may be affected including hard palate and lips. The etiology of this disorder remains poorly understood, but the various factors might be related with the pathogenesis of the BMS. These factors have been devided into local, systemic and psychological. Recently, there have been increasing reports that the pain of BMS may be neuropathic in origin. The complex and multifactorial etiology of BMS necessitates multidisciplinary approach for the management of these patients. Recently, several studies have reported that oral parafunctional habits could be related the pathogenesis of BMS, and tried to control the symptom of BMS with various methods. We reported the cases who had the symptom of burning mouth syndrome with removable anti-nociceptive appliance in the lower dentition.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.1
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• pp.28-32
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• 2014

For a signal such as speech showing piece-wise linear shape in a very short time period, a nonuniform sampling method based on the inflection point detection (IPD) is proposed to reduce data rate. The method exploits the geometrical characteristics of signal further than the existing local maxima/minima detection (MMD) based sampling method. As results, the reconstructed signal by the interpolation of the IPD based sampled data resembles the original speech more. Computer simulation shows that the proposed IPD based method produces about 9~23 dB improvement over the existing MMD method. To show the usefulness of the IPD technique, it is applied to speech coding, and compared to the continuously variable slope delta modulation (CVSD). The nonuniformly sampled data is binary coded with one bit flag set "1". Noninflection samples are not sent, but only flag bits set 0 are sent. The method shows 0.3 ~ 9 dB SNR and 0.5 ~ 1.3 mean opinion score (MOS) improvements over the CVSD.