• 응용통계연구
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• 제19권3호
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• pp.587-598
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• 2006

본 논문에서는 마이크로어레이 (microarray) 자료에 판별분석을 적용 시 나타나는 고차원 및 소표본 문제의 해결방법으로서 직교요인을 새로운 특징변수로 사용한 비모수적 국소선형 로지스틱 판별분석을 제안한다. 제안된 방법은 국소우도에 기반한 것으로서 다범주 판별분석에 적용될 수 있으며, 고려된 직교인자는 주성분 요인, 부분최소제곱 요인, 인자분석 요인 등이다. 대표적인 두 가지 실제 마이크로어레이 자료에 적용한 결과 직교요인들 중에서 부분최소제곱 요인을 특징변수로 사용한 경우 고전적인 통계적 판별분석보다 향상된 분류 능력을 나타내고 있음을 확인하였다.

• 한국시뮬레이션학회논문지
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• 제20권4호
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• pp.31-40
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• 2011

센서 노드는 악의적인 공격자들에 의해 물리적인 공격들에 쉽게 노출된다. 공격자는 훼손 노드를 이용하여 센서 네트워크에 다양한 공격을 발생시킬 수 있다. 그 중 응용 계층에서 발생하는 허위 보고서 삽입 공격은 훼손된 노드를 통해 네트워크 내에 위조 보고서를 주입한다. 주입된 위조 보고서는 BS까지 전달될 경우 허위 경보뿐만 아니라 노드의 불필요한 에너지 소모를 유발한다. 이러한 공격을 방어하기 위해 통계적 여과 기법은 BS까지 전달되는 허위 보고서를 전달 과정 중 가능한 빨리 여과시키기 위해 제안되었다. 이 기법의 성능 향상을 위해 제안된 기법 중 경로 갱신 기법은 통계적 여과 기법의 탐지 능력 유지하고 노드의 균형 있는 에너지 소모를 위해 제안되었다. 본 논문은 경로 경신 방법에서 경로 갱신에 필요한 에너지의 효율적인 소비를 위해 보안 경로 주기 결정 방법을 제안한다. 보안 경로 주기를 선택하기 위해 BS에서 센서 노드들의 홉 수와 보고서 전송량을 고려하여 평가 함수를 통해 결정한다. 그리고 시뮬레이션을 통해 위 3가지 기법들과 제안 기법을 비교하여 에너지 효율성을 평가한다. 그러므로 제안 기법은 보안 경로 설정을 유지하면서, 네트워크 내에 균형 있는 에너지 소비의 효율을 높인다.

• Toxicological Research
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• 제28권2호
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• pp.129-137
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• 2012

Probabilistic ecological risk assessment (PERA) for deriving ecological protective concentration (EPC) was previously suggested in USA, Australia, New Zealand, Canada, and Netherland. This study suggested the EPC of cadmium (Cd) based on the PERA to be suitable to Korean aquatic ecosystem. First, we collected reliable ecotoxicity data from reliable data without restriction and reliable data with restrictions. Next, we sorted the ecotoxicity data based on the site-specific locations, exposure duration, and water hardness. To correct toxicity by the water hardness, EU's hardness corrected algorithm was used with slope factor 0.89 and a benchmark of water hardness 100. EPC was calculated according to statistical extrapolation method (SEM), statistical extrapolation $method_{Acute\;to\;chronic\;ratio}$ ($SEM_{ACR}$), and assessment factor method (AFM). As a result, aquatic toxicity data of Cd were collected from 43 acute toxicity data (4 Actinopterygill, 29 Branchiopoda, 1 Polychaeta, 2 Bryozoa, 6 Chlorophyceae, 1 Chanophyceae) and 40 chronic toxicity data (2 Actinopterygill, 23 Branchiopoda, 9 Chlorophyceae, 6 Macrophytes). Because toxicity data of Cd belongs to 4 classes in taxonomical classification, acute and chronic EPC (11.07 ${\mu}g/l$ and 0.034 ${\mu}g/l$, respectively) was calculated according to SEM technique. These values were included in the range of international EPCs. This study would be useful to establish the ecological standard for the protection of aquatic ecosystem in Korea.

• 부모자녀건강학회지
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• 제7권2호
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• pp.160-167
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• 2004

Purpose: The purpose of this study was to examine the effect of a preparation method using hospital play on anxiety and role behaviors of children undergoing tonsillectomy. Method: Twenty-eight children aged 5 to 7 years who were admitted for tonsillectomy were assigned to either an experimental group or a control group purposefully. The preparation method included provision of information using hospital play. The data were analyzed using Mann-Whitney test and Chi-square test. Result: There was no Significant difference in anxiety before surgery between the experimental and control groups. Also, there was no Significant difference in role behaviors on the 1st and the 2nd day of surgery. Conclusion: Even though there was no statistical significance, the result showed that the preparation method had some positive effect on children and parents. It is needed to develop systematic preparation methods for children undergoing surgery to enhance their coping.

• 천문학회지
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• 제55권3호
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• pp.67-74
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• 2022

In this study, we perform a statistical investigation of the kinematic classification of 4,264 coronal mass ejections (CMEs) from 1996 to 2015 observed by SOHO/LASCO C3. Using the constant acceleration model, we classify these CMEs into three groups: deceleration, constant velocity, and acceleration motion. For this, we devise three different classification methods using fractional speed variation, height contribution, and visual inspection. The main results of this study can be summarized as follows. First, the fractions of three groups depend on the method used. Second, about half of the events belong to the groups of acceleration and deceleration. Third, the fractions of three motion groups as a function of CME speed are consistent with one another. Fourth, the fraction of acceleration motion decreases as CME speed increases, while the fractions of other motions increase with speed. In addition, the acceleration motions are dominant in low speed CMEs whereas the constant velocity motions are dominant in high speed CMEs.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.144-147
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• 2000

A numerical method for the solution of one-dimensional inverse heat conduction problem is established and its performance is demonstrated with computational results. The present work introduces the maximum entropy method in order to build a robust formulation of the inverse problem. The maximum entropy method finds the solution that maximizes the entropy functional under given temperature measurement. The philosophy of the method is to seek the most likely inverse solution. The maximum entropy method converts the inverse problem to a non-linear constrained optimization problem of which constraint is the statistical consistency between the measured temperature and the estimated temperature. The successive quadratic programming facilitates the maximum entropy estimation. The gradient required fur the optimization procedure is provided by solving the adjoint problem. The characteristic feature of the maximum entropy method is discussed with the illustrated results. The presented results show considerable resolution enhancement and bias reduction in comparison with the conventional methods.

• 한국산림과학회지
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• 제96권4호
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• pp.483-493
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• 2007

본 연구는 조건부가치평가법을 사용하여 순천 희어리 군락지의 생물다양성 보전가치를 추정하는데 목적이 있다. 지불의사유도 방법에 따라 3가지 다른 모형별로 순천 희어리 군락지의 생물다양성 보전가치를 추정하여 제시하였다. 추정된 금액의 평균값을 계산하여 보면, 멸종위기 희귀식물종 서식지역(순천시 서면 히어리 군락지)의 생물다양성 보전에 따른 순천지역 주민의 가구당 월 평균지불의사금액은 약 3,380원, 연간 총 가치는 약 33억원으로 추정되었다. 이러한 추정결과는 순천시 서면 히어리 군락지에 생물다양성 보전프로그램이 실시될 경우, 지역주민의 생계활동(농사, 임업 등)과 관련된 편익, 생태관광 및 산책과 같은 여가활동으로 인한 편익, 후손 및 미래이용을 위한 편익, 그리고 멸종위기 희귀동식물 서식지역 보호로 인한 편익 등의 가치가 약 33억원 발생한다는 것을 시사하고 있다.

• Wind and Structures
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• 제36권2호
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• pp.133-147
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• 2023

The random vibration of saddle membrane structures under wind load is studied theoretically and experimentally. First, the nonlinear random vibration differential equations of saddle membrane structures under wind loads are established based on von Karman's large deflection theory, thin shell theory and potential flow theory. The probabilistic density function (PDF) and its corresponding statistical parameters of the displacement response of membrane structure are obtained by using the diffusion process theory and the Fokker Planck Kolmogorov equation method (FPK) to solve the equation. Furthermore, a wind tunnel test is carried out to obtain the displacement time history data of the test model under wind load, and the statistical characteristics of the displacement time history of the prototype model are obtained by similarity theory and probability statistics method. Finally, the rationality of the theoretical model is verified by comparing the experimental model with the theoretical model. The results show that the theoretical model agrees with the experimental model, and the random vibration response can be effectively reduced by increasing the initial pretension force and the rise-span ratio within a certain range. The research methods can provide a theoretical reference for the random vibration of the membrane structure, and also be the foundation of structural reliability of membrane structure based on wind-induced response.

• 한국농공학회논문집
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• 제48권2호
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• pp.27-35
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• 2006

Large dams are managed with operation standard and flood forecasting systems, while small dams do not have management method generally. Shortage of water resources and natural disasters due to drought and flood raised public concerns for management of small dams. Most of small dams are irrigation dams, which need diversified water uses. However, the lack of systematic management of small dams have caused serious water wastage and increased natural disasters. Storage management method and system were developed to solve these problems in small dams. The system was applied to Seongju dam for effective management. The storage management method was established considering hydrology simulation and statistical analysis using the system. This method can bring additional available water, even in the same conditions of the water demand and the supply conditions of watershed. It can improve the flood control capacity and water utilization efficiency by' the flexible operation of storage space.

• Journal of the Korean Data and Information Science Society
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• 제13권2호
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• pp.227-234
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• 2002

In this paper, we consider hierarchical Bayes generalized linear models for the analysis of longitudinal count data. Specifically we introduce the hierarchical Bayes random effects models. We discuss implementation of the Bayes procedures via Markov chain Monte Carlo (MCMC) integration techniques. The hierarchical Baye method is illustrated with a real dataset and is compared with other statistical methods.