• 융합신호처리학회논문지
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• 제8권3호
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• pp.143-148
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• 2007

영상처리에 있어서 갑작스러운 신호와 불확실한 시스템의 특징을 정확하게 표현하기 위하여 많은 연구가 수행되어 왔다. 많이 알려진 퓨리어 변환은 임의 신호의 주파수 해석에 폭넓게 사용되어 왔다. 그러나 이 방법은 시간 축에서 발생하는 갑작스러운 신호 변환과 비정상적인 신호를 주파수 변환 영역에서 나타낼 수 없으므로 유용하지 않다. 본 논문은 이산 웨이브렛을 이용한 영상해석을 하였다. 이는 웨이브렛 영역에서의 극대치는 Lipschitz 지수 표현이 가능하고, 또한 극대치만 사용하여 영상 데이터의 윤곽선 및 데이터 특성을 표현하는 유용함을 나타내었다. 더욱이 적은 극대치만을 사용하여 본래 영상을 재생하는 것도 가능하게 되었다. fractal 해석은 예로서 적용되었다. 그리고, 모형 배에서 기름 띠의 가시화 영상이 해석되었다. 극대치 해석으로 fractal 변수를 구하고, 가시화 영상 해석의 실험으로 양호한 결과를 얻었다.

• 한국초등수학교육학회지
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• 제9권2호
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• pp.181-200
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• 2005

구성주의 관점에 의하면 수학적 지식은 교사가 일방적으로 전수하는 것이 아니라 학생들이 자발적인 방법으로 스스로의 지식을 형성해 가는 것이다. 특히 사회적 구성주의에서는 사회구성원간의 의사소통을 통해 수학지식이 형성됨을 강조하고 있다. 일반적으로 학생들의 의사소통은 소집단 협동학습의 환경에서 가장 활발하게 이루어진다. 문제해결을 위해 학생들은 각자의 생각을 교환하고 자유롭게 질문하며 상호간의 사고와 개념을 명확하게 하고 의미 있는 방법으로 서로의 학습에 도움을 주게 된다. 본 연구에서는 6학년 학생들이 수학적 논의를 하는 과정에서 사용하는 의사소통의 수단을 언어와 행동의 관점으로 분석하여 매 수업 장면에서는 관찰하기 어려운 소집단 협동학습 내의 집단적인 역학관계를 파악하고자 한다.

• 스마트미디어저널
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• 제7권1호
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• pp.9-15
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• 2018

기관 또는 조직은 비즈니스 시스템의 규모가 커지면서 이들과 관련된 서로 다른 시스템에서 다양한 대량의 데이터들이 생성되고 있다. 이와 같이 비즈니스 환경에서 서로 다른 시스템에서 데이터를 보다 스마트하게 처리하여 효율성을 높일 수 있는 방법이 필요하다. 이를 위한 가장 기본적인 접근 방법 중 하나는 DataLake와 같이 데이터를 정확하게 설명하고 전체 비즈니스에 대한 가장 중요한 데이터를 나타낼 수 있는 단일 도메인 모델을 만드는 것이다. DataLake의 장점을 구현하기 위해서는 다양하게 요구되어진 기능들을 어떤 구조로, 어떻게 작동 할 것인지에 대한 DataLake의 구성 요소들을 정의하는 게 중요하며, DataLake의 구성 요소들에 의해서 데이터 흐름에 따른 라이프 사이클을 갖게 된다. 또한 데이터 획득 시점에서 DataLake로 유입되는 동안 메타 데이터는 데이터 추적 가능성, 데이터 계보 및 라이프 사이클 전반의 데이터 민감도에 기반 한 보안 측면과 함께 캡처 및 관리되어야 하며, 이러한 이유로 Abyss Storage Cluster 기반의 DataLake Framework를 설계하였다.

• International Journal of Fluid Machinery and Systems
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• 제8권4호
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• pp.264-273
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• 2015

This presentation describes an experimental approach for the detection of cavitation in hydraulic machines by use of ultrasonic signal analysis. Instead of using the high frequency pulses (typically 1MHz) only for transit time measurement different other signal characteristics are extracted from the individual signals and its correlation function with reference signals in order to gain knowledge of the water conditions. As the pulse repetition rate is high (typically 100Hz), statistical parameters can be extracted of the signals. The idea is to find patterns in the parameters by a classifier that can distinguish between the different water states. This classification scheme has been applied to different cavitation sections: a sphere in a water flow in circular tube at the HSLU in Lucerne, a NACA profile in a cavitation tunnel and two Francis model test turbines all at LMH in Lausanne. From the signal raw data several statistical parameters in the time and frequency domain as well as from the correlation function with reference signals have been determined. As classifiers two methods were used: neural feed forward networks and decision trees. For both classification methods realizations with lowest complexity as possible are of special interest. It is shown that two to three signal characteristics, two from the signal itself and one from the correlation function are in many cases sufficient for the detection capability. The final goal is to combine these results with operating point, vibration, acoustic emission and dynamic pressure information such that a distinction between dangerous and not dangerous cavitation is possible.

• Nuclear Engineering and Technology
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• 제46권5호
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• pp.633-640
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• 2014

In this research, the surface roughness affecting the pressure drop in a pipe used as the steam generator of a PWR was studied. Based on the CFD (Computational Fluid Dynamics) technique using a commercial code named ANSYS-FLUENT, a straight pipe was modeled to obtain the Darcy frictional coefficient, changed with a range of various surface roughness ratios as well as Reynolds numbers. The result is validated by the comparison with a Moody chart to set the appropriate size of grids at the wall for the correct consideration of surface roughness. The pressure drop in a full-scale U-shaped pipe is measured with the same code, correlated with the surface roughness ratio. In the next stage, we studied a reduced scale model of a U-shaped heat pipe with experiment and analysis of the investigation into fluid-structure interaction (FSI). The material of the pipe was cut from the real heat pipe of a material named Inconel 690 alloy, now used in steam generators. The accelerations at the fixed stations on the outer surface of the pipe model are measured in the series of time history, and Fourier transformed to the frequency domain. The natural frequency of three leading modes were traced from the FFT data, and compared with the result of a numerical analysis for unsteady, incompressible flow. The corresponding mode shapes and maximum displacement are obtained numerically from the FSI simulation with the coupling of the commercial codes, ANSYS-FLUENT and TRANSIENT_STRUCTURAL. The primary frequencies for the model system consist of three parts: structural vibration, BPF(blade pass frequency) of pump, and fluid-structure interaction.

• 정보처리학회논문지B
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• 제14B권3호
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• pp.199-214
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• 2007

최근 들어 인공지능 계획기법을 이용하여 자동화된 시맨틱 웹서비스들 간의 조합을 구현하려는 연구들이 활발하게 이루어지고 있다. 하지만 일반적으로 전통적인 인공지능 계획기법들은 복잡한 제어구조를 포함하는 웹서비스 프로세스를 하나의 단위 행동이나 계획으로 표현하기 어렵고, 온톨로지에 포함된 의미 정보들을 계획생성에 충분히 반영할 수 없으며, 웹서비스들 사이의 입출력 데이터 흐름을 직접 모델링할 수 없고, 계획단계와 실행단계가 분리되어 있어 웹서비스 실행단계의 불확실성과 가변성을 계획단계에서 충분히 고려할 수 없다는 등의 한계점을 가지고 있다. 본 연구에서는 이러한 문제점들을 해결하기 위한 접근 방법으로서 반응형 계획을 이용한 시맨틱 웹서비스 조합을 제안하고, 프로토타입 시스템인 SWEEP을 구현하였다. e-Commerce 분야의 예제 웹서비스들을 대상으로 실험을 통해, 우리는 반응형 계획이 자동화된 시맨틱 웹서비스의 조합과 실행을 구현하기 위한 효과적인 기술임을 확인할 수 있었다.

• IMMUNE NETWORK
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• 제7권3호
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• pp.141-148
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• 2007

Background: Anti-IgE mAb which binds circulating but not receptor-bound IgE has been shown to be effective in treatment for asthma and other allergic diseases. However, the mechanisms by which anti-IgE mAb influences the pathophysiological responses are remained to be illustrated. This study was undertaken to examine the therapeutic efficacy of non-anaphylactogenic anti-mouse IgE mAb using murine models of IgE-induced systemic fatal anaphylaxis. Methods: Active systemic anaphylaxis was induced by either penicillin V(Pen V) or OVA and passive systemic anaphylaxis was induced by either anaphylactogenic anti-mouse IgE or a mixture of anti-chicken gamma globulin (CGG) IgG1 mAb and CGG. The binding of the Fc portion of anti-IgE to CHO-stable cell line expressing mouse Fc ${\gamma}$ RIIb was examined using flow cytometry. Fc fragments of anti-IgE mAb were prepared using papain digestion. The expression of phosphatases in lungs were assessed by Western blotting and immunohistochemistry. Results: Anti-IgE mAb prevented IgE- and IgG-induced active and passive systemic fatal reactions. In both types of anaphylaxis, anti-IgE mAb suppressed antigen-specific IgE responses, but not those of IgG. Anti-IgE mAb neither prevented anaphylaxis nor suppressed the IgE response in Fc ${\gamma}$ RIIb-deficient mice. The Fc portion of anti-IgE mAb was bound to murine Fc ${\gamma}$ RIIb gene-transfected CHO cells and inhibited systemic anaphylaxis. Anti-IgE mAb blocked the anaphylaxis-induced downregulation of Fc ${\gamma}$ RIIb-associated phosphatases such as src homology 2 domain-containing inositol 5-phosphatase (SHIP) and phosphatase and tensin homologue deleted on chromosome ten (PTEN). Conclusion: Anti-IgE mAb prevented anaphylaxis by delivering nonspecific inhibitory signals through the inhibitory IgG receptor, Fc ${\gamma}$ RIIb, rather than targeting IgE.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권5호
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• pp.56-67
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• 2012

In the present study, an enhanced subsurface prediction algorithm based on a non-parametric geostatistical model and a history matching technique through Gibbs sampler is developed and the iterative prediction improvement procedure is proposed. The developed model is applied to a simple two-dimensional synthetic case where domain is composed of three different hydrogeologic media with $500m{\times}40m$ scale. In the application, it is assumed that there are 4 independent pumping tests performed at different vertical interval and the history curves are acquired through numerical modeling. With two hypothetical borehole information and pumping test data, the proposed prediction model is applied iteratively and continuous improvements of the predictions with reduced uncertainties of the media distribution are observed. From the results and the qualitative/quantitative analysis, it is concluded that the proposed model is good for the subsurface prediction improvements where the history data is available as a supportive information. Once the proposed model be a matured technique, it is believed that the model can be applied to many groundwater, geothermal, gas and oil problems with conventional fluid flow simulators. However, the overall development is still in its preliminary step and further considerations needs to be incorporated to be a viable and practical prediction technique including multi-dimensional verifications, global optimization, etc. which have not been resolved in the present study.

• Tribology and Lubricants
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• 제32권3호
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• pp.101-105
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• 2016

Trap effect of groove is evaluated in a lubricating system using computational fluid dynamics (CFD) analysis. The simulation is based on the standard k-ε turbulence model and the discrete phase model (DPM) using a commercial CFD code FLUENT. The simulation results are also capable of showing the particle trajectories in flow field. Computational domain is meshed using the GAMBIT pre-processor. The various grooves are applied in order to improve lubrication characteristics such as reduction of friction loss, increase in load carrying capacity, and trapping of the wear particles. Trap effect of groove is investigated with variations in cross-sectional shape and Reynolds number in this research. Various cross-sectional shapes of groove (rectangular, triangle, U shaped, trapezoid, elliptical shapes) are considered to evaluate the trap effect in simplified two-dimensional sliding bearing. The particles are assumed to steel, and defined a single particle injection condition in various positions. The “reflect” boundary condition for discrete phase is applied to the wall boundary, and the “escape” boundary condition to “pressure inlet” and “pressure outlet” conditions. The streamlines are compared with particles trajectories in the groove. From the results of numerical analysis in the study, it is found that the cross-sectional shapes favorable to the creation of vortex and small eddy current are effective in terms of particle trapping effect. Moreover, it is found that the Reynolds number has a strong influence on the pattern of vortex or small eddy current in the groove, and that the pattern of the vortex or small eddy current affects the trap effect of the groove.

• 임상간호연구
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• 제25권3호
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• pp.251-264
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• 2019

Purpose: This study was a systematic review and meta-analysis to explore the factors related to quality of life in heart transplant recipients. Methods: To identify studies that suggested the factors related to the quality of life in heart transplant recipients, we searched the articles published from 1974 to November 2018 using Six databases, PubMed, CINAHL, EMBASE, Cochrane, KMBASE and RISS. A total of 22 studies were selected out of 5,234 for the systematic review and meta-analysis on the basis of the PRISMA flow. The quality of study was assessed by assessment tool form the NIH and meta-analysis was performed using the 'R 3.5.2' version to analyze the correlated effect sizes. Results: Factors related to quality of life in heart transplant recipients were categorized into six domains based on the health-related quality of life model introduced by Ferrans: individual, environmental, biological function, symptoms, functional status, and general health perception. In the meta-analysis, 34 factors were used and 17 factors having significant effect sizes were as follows: self-efficacy, demoralization, perceived control, current occupational status, age, marital status, health promotion life style in the individual characteristics; stress in environmental characteristics; physical function status, creatinine level, left ventricular ejection fraction (LVEF) in biological function; anxiety, depression, symptom frequency and distress in symptoms domain; coping, self-care compliance in functional status. Conclusion: The findings indicate that the multi-dimensional factors influencing the quality of life in heart transplant recipients and provide the evidence for developing effective interventions for improving the quality of life of recipients.