• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2018년도 추계학술대회
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• pp.177-180
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• 2018

As ships operating on the Arctic route are exposed to various ice environments such as level ice, pre-swan, pack ice, ice ridge and brash ice, it is essential to estimate the ice resistance according to the ice environment. Methods for estimating the ice resistance include a method using mathematical model, numerical simulation, and a method using empirical formula. In this study, empirical formulas are used to estimate the ice resistance. The purpose of this study is to develop the ice resistance and attainable speed estimation program(I-RES) for various ice environments.

• 콘크리트학회논문집
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• 제11권3호
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• pp.69-80
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• 1999

The strengthening of reinforced concrete structures by externally bonded GFRP has become increasingly common in resent years. However the analysis and design method for GFRP plate strengthening of RC beams is not well established yet. The purpose of present paper is, therefore, to define the failure mechanism and failure behavior of strengthened RC beam using GFRP and then to propose a resonable method for the calculation of interface debonding load for those beams. From the experimental results of beams strengthened by GFRP, the influence of length and thickness, width of plate on the interfacial debonding failure behavior of beam is studied and, on the basis of test results, the semi-empirical equation to predict debonding load is developed. The proposed theory based on nonlinear analysis and critical flexural crack width, predicts relatively well the debonding failure load of test beams and may be efficiently used in the analysis and design of strengthened RC beams using GFRP.

• 한국세라믹학회지
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• 제24권1호
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• pp.47-55
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• 1987

The purpose of this work is to establish the basic calibration data for the efficiency of grinding by investigating the Bond's Work Index employing Korean Kaolin as a reference mateial with the laboratory-scale ball mill. A small ordinary ball mill has a dimension of 133 inside diameter and 144mm long. The analysis of the experimental results in this work sets up a equivalent calibration method with the laboratory-scale ball mill to those with special mill. The theoretical expression, derived from the rate equation proposed by Miwa, is obtained to anticipitate the stable revolution number for the next grinding cycle. The proposed equation is more systematic and acurate than lshihara's empirical equation is more systematic and acurate than lshihara's empirical equation for the measurement of gindability of a ball mill.

• Current Optics and Photonics
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• 제2권5호
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• pp.413-421
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• 2018

We propose a novel methodology based on the multiplication function to improve the signal-to-noise ratio (SNR) for vibration detection in a phi optical time-domain reflectometer system (phi-OTDR). The extreme-mean complementary empirical mode decomposition (ECEMD) is designed to break down the original signal into a set of inherent mode functions (IMFs). The multiplication function in terms of selected IMFs is used to determine a vibration's position. By this method, the SNR of a phi-OTDR system is enhanced by several orders of magnitude. Simulations and experiments applying the method to real data prove the validity of the proposed approach.

• Genomics & Informatics
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• 제16권4호
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• pp.37.1-37.3
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• 2018

Gene-gene interaction is a key factor for explaining missing heritability. Many methods have been proposed to identify gene-gene interactions. Multifactor dimensionality reduction (MDR) is a well-known method for the detection of gene-gene interactions by reduction from genotypes of single-nucleotide polymorphism combinations to a binary variable with a value of high risk or low risk. This method has been widely expanded to own a specific objective. Among those expansions, fuzzy-MDR uses the fuzzy set theory for the membership of high risk or low risk and increases the detection rates of gene-gene interactions. Fuzzy-MDR is expanded by a maximum likelihood estimator as a new membership function in empirical fuzzy MDR (EFMDR). However, EFMDR is relatively slow, because it is implemented by R script language. Therefore, in this study, we implemented EFMDR using RCPP ($c^{{+}{+}}$ package) for faster executions. Our implementation for faster EFMDR, called EMMDR-Fast, is about 800 times faster than EFMDR written by R script only.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.913-916
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• 2006

Spatial distribution, seasonal and interannual variability of chlorophyll a concentration in Okhotsk Sea from SeaWiFS data between 2001 and 2004 were describe. An Empirical Orthogonal Function method was applied for analysis data. The ten modes described about 85% of total variance. Two maxima were defined - more intensive in spring and weaker in autumn. The first mode showed zones with chlorophyll a concentration during maximum bloom. The second mode specified timing of spring bloom in various regions in Okhotsk Sea. Analysis of SeaWiFS data indicated connection between highest chlorophyll a concentration and sea surface temperature limits during spring bloom. Similar relation was not found during fall bloom.

• Steel and Composite Structures
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• 제42권5호
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• pp.671-683
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• 2022

To investigate and predict the long-term time-dependent behavior, such as creep, shrinkage, and relaxation of PS strands, and prestress loss in prestressed steel-concrete composite beams, named Precom, full-scale tests were conducted and the collected data were compared with those obtained from the two proposed analytical models. The combined effective modulus method (EMM)-empirical model proposed with a flowchart considered the creep effect to determine the prestress loss. Conversely, the age-adjusted effective modulus method (AEMM) with CEB-FIP equation was developed to account for the concrete aging. The results indicated that the AEMM with CEB-FIP model predicts the long-term behavior of Precom effectively.

• 대한교통학회지
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• 제31권6호
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• pp.67-89
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• 2013

본 연구는 관찰적 사전 사후 평가연구의 세 방법인 단순비교법, 비교그룹에 의한 방법 그리고 경험적 베이즈 방법에 대한 실증 분석을 수행하고, 그 결과를 비교하며, 평가연구에 적용 방안을 제시하고자 한다. 이를 위해 2005년과 2006년에 영동고속도로에서 시행된 안전진단사업의 평가를 수행하였다. 분석결과 세 가지 방법 모두 안전진단조치로 인한 개선효과가 나타나고 있으며, 단순비교법이 개선효과가 가장 크고 그 다음이 비교그룹에 의한 방법, 경험적 베이즈 방법의 순으로 나타났다. 단순비교법의 결과는 교통사고 감소추이가 반영되어 과대 추정되었으며, 비교그룹방법의 결과에는 비교그룹의 외부우연요인이 내재되어 있다. 경험적 베이즈 방법은 참조그룹의 사고예측모형에 의해 평균으로의 회귀 현상이 통제되므로, 두 방법과 비교해 결과가 비교적 정확하다. 평가연구의 수행에서, 분석가는 평가방법별 장 단점을 잘 이해하고, 관련된 모든 지역에서 사고추이의 검토를 선행한 후에 평가 분석을 수행하여야 한다.

• 화약ㆍ발파
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• 제34권4호
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• pp.28-34
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• 2016

화약류, 인화성 액체와 가스 또는 먼지 등의 폭발에 의해 유발된 폭발효과를 평가하는데 경험적모델, 현상학적모델 및 전산유체역학모델이 사용된다. 경험적모델의 한 종류인 TNT등가법은 사용이 매우 단순하기 때문에 현재까지도 널리 사용되고 있다. 본 연구에서는 TNT 폭발 실험으로부터 얻어진 최대과압-환산거리 곡선과 환산충격량-환산거리 곡선을 피팅하여 새로운 회귀식을 유도하였다. 폭발성 물질의 TNT 등가질량만 알면 본 연구에서 유도한 회귀식을 이용하여 거리에 따른 최대과압과 충격량을 평가하는 것이 가능하다. TNT등가법의 한 성분인 수율계수의 크기를 달리하여 최대과압을 구한 결과 압력의 증가가 급격히 나타나는 폭원으로부터 근접한 거리에서는 수율계수에 따라 최대과압의 차가 크게 발생하는 반면에 거리가 증가함에 따라 그 차이는 감소하는 것으로 나타났다.

• Journal of the Korean Data and Information Science Society
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• 제7권2호
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• pp.235-245
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• 1996

확률변수 (X,Y)가 이변량 정규분포를 따르는 경우, 모상관계수 ${\rho}$에 관한 여러 가설들 중에서 $H_{0}:{\rho}={\rho}_{0}$인 경우에는 알려진 분포를 이용한 통계적 추론을 하기가 어렵다. 이러한 경우 Fisher에 의해 제안된 Z-변환을 이용한 근사적 검정법이 사용되어 오고 있으나 근사적인 방법이기 때문에 주어진 표본의 크기가 충분히 많지 않은 경우에는 적용에 무리가 있을 수 있다. 그래서 본 논문에서는 먼저 표본 상관계수 R의 분포를 모의실험을 통하여 직접 구하여 검정한 정확 검정법과, 붙스트랩(bootstrap) 방법을 이용하여 구한 붙스트랩 검정법을 제시하고, Fisher의 방법의 효율성과 실제성을 검토하고 제시된 방법들과 서로 비교하고자 한다.