• Computers and Concrete
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• 제14권5호
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• pp.577-597
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• 2014

This paper aims to develop a prediction model for the hardened properties of waste LCD glass that is used in concrete by analyzing a series of laboratory test results, which were obtained in our previous study. We also summarized the testing results of the hardened properties of a variety of waste LCD glass concretes and discussed the effect of factors such as the water-binder ratio (w/b), waste glass content (G) and age (t) on the concrete compressive strength, flexural strength and ultrasonic pulse velocity. This study also applied a hyperbolic function, an exponential function and a power function in a non-linear regression analysis of multiple variables and established the prediction model that could consider the effect of the water-binder ratio (w/b), waste glass content (G) and age (t) on the concrete compressive strength, flexural strength and ultrasonic pulse velocity. Compared with the testing results, the statistical analysis shows that the coefficient of determination $R^2$ and the mean absolute percentage error (MAPE) were 0.93-0.96 and 5.4-8.4% for the compressive strength, 0.83-0.89 and 8.9-12.2% for the flexural strength and 0.87-0.89 and 1.8-2.2% for the ultrasonic pulse velocity, respectively. The proposed models are highly accurate in predicting the compressive strength, flexural strength and ultrasonic pulse velocity of waste LCD glass concrete. However, with other ranges of mixture parameters, the predicted models must be further studied.

• Genomics & Informatics
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• 제13권4호
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• pp.126-131
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• 2015

Fulminant type 1 diabetes (T1DM) is a distinct subtype of T1DM that is characterized by rapid onset hyperglycemia, ketoacidosis, absolute insulin deficiency, and near normal levels of glycated hemoglobin at initial presentation. Although it has been reported that class II human leukocyte antigen (HLA) genotype is associated with fulminant T1DM, the genetic predisposition is not fully understood. In this study we investigated the HLA genotype and haplotype in 11 Korean cases of fulminant T1DM using imputation of whole exome sequencing data and compared its frequencies with 413 participants of the Korean Reference Panel. The $HLA-DRB1^*04:05-HLA-DQB1^*04:01$ haplotype was significantly associated with increased risk of fulminant T1DM in Fisher's exact test (odds ratio [OR], 4.11; 95% confidence interval [CI], 1.56 to 10.86; p = 0.009). A histidine residue at $HLA-DR{\beta}1$ position 13 was marginally associated with increased risk of fulminant T1DM (OR, 2.45; 95% CI, 1.01 to 5.94; p = 0.054). Although we had limited statistical power, we provide evidence that HLA haplotype and amino acid change can be a genetic risk factor of fulminant T1DM in Koreans. Further large-scale research is required to confirm these findings.

• Wind and Structures
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• 제32권3호
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• pp.227-238
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• 2021

This study analyzed the pressure patterns and local pressure of tall buildings with corner modifications (recessed and chamfered corner) using wind tunnel tests and proper orthogonal decomposition (POD). POD can distinguish pressure patterns by POD mode and more dominant pressure patterns can be found according to the order of POD modes. Results show that both recessed and chamfered corners effectively reduced wind-induced responses. Additionally, unique effects were observed depending on the ratio of corner modification. Tall building models with recessed corners showed fluctuations in the approaching wind flow in the first POD mode and vortex shedding effects in the second POD mode. With large corner modification, energy distribution became small in the first POD mode, which shows that the effect of the first POD mode reduced. Among building models with chamfered corners, vortex shedding effects appeared in the first POD mode, except for the model with the highest ratio of corner modifications. The POD confirmed that both recessed and chamfered corners play a role in reducing vortex shedding effects, and the normalized power spectral density peak value of modes showing vortex shedding was smaller than that of the building model with a square section. Vortex shedding effects were observed on the front corner surfaces resulting from corner modification, as with the side surface. For buildings with recessed corners, the local pressure on corner surfaces was larger than that of side surfaces. Moreover, the average wind pressure was effectively reduced to 88.42% and 92.40% in RE1 on the windward surface and CH1 on the side surface, respectively.

• 대한치과기공학회지
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• 제34권3호
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• pp.213-220
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• 2012

Purpose: The aim of this study was to determine the repeatability and reproducibility of two dental scanners. Methods: The master die and the stone replicas(Kavo, Germany) were digitized in touch-probe scanner(Incise, Renishaw, UK), white light scanner(Identica, Medit, Korea) to create 3-dimensional surface-models. The number of points in the point clouds from each reading were calculated and used as the CAD reference model(CRM). Discrepancies between the points in the 3-dimensional surface models and the corresponding CRM were measured by a matching-software(Power-Inspect R2, Delcam Plc, UK). The t-student test for one samples were used for statistical analysis. Results: The reproducibility of both scanner was within $3{\mu}m$, based on mean value. The mean value between measurements made directly on the touch probe scanner digital models and those made on the white light scanner digital models was $2.20-2.90{\mu}m$, and was statistically significant(P<0.05). Conclusion: With respect to adequate data acquisition, the reproducibility of dental scanner differs. Three-dimensional analysis can be applied to differential quality analysis of the manufacturing process as well as to evaluation of different analysis methods.

• 한국전자파학회논문지
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• 제15권3호
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• pp.291-300
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• 2004

이동통신 서비스의 급격한 증가로 인해, EMF(Electromagnetic field)노출의 생물학적 효과에 대한 많은 연구들이 수행되어져 왔다. 그러나 연구 수행에 있어서 필요한 무선 주파수 대역에서의 균일장 생성은 쉬운 일이 아니다. 이러한 어려움을 극복하기 위해 전신노출 시 스템에서의 전기장과 SAR(Specific Absorption Rate) 분포 측정이 발전을 해왔다. 본 논문에서는 EMC 대용 챔버로의 활용 가능성이 높은 전자파 잔향실 챔버를 이용하여 동물 실험용 전신 노출 장치를 개발하였다. 설계된 전자파 잔향실은 시뮬레이션과 측정 데이터를 이용하여 시험영역의 균일장에 대한 유효성을 검증하였다. 마우스에 대한 전신노출 실험에 있어서, 노출된 전자파에 대해 SAR을 확인하기 위해서 FDTD수치해석 방법과 측정 결과를 비교하였다. 전자파 잔향실 내부에서의 전기장 분포 특성을 해석하고, 이러한 해석 결과들을 통계적으로 처리하였다. CDMA 이동전화 주파수 대역에서(PCS ＆ Cellular 대역) 입력 파워 변화에 따른 실험상태에서의 마우스 전신 SAR 평균값 및 국부 최대값을 제시하였다.

• 한국임상수의학회지
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• 제27권1호
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• pp.66-70
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• 2010

Reference interval is critical for interpreting laboratory results, monitoring response to therapy and predicting the prognosis of the patients in clinical settings. The aim of the present study was to update established reference intervals for routine hematologic and serum chemistry values for a population of clinically healthy dogs (range, 1-8 years) seen in an animal hospital. Blood was obtained by venipuncture while animals were physically restrained, and samples were analyzed for 9 chemistries on MS9-5H (Melot Schloesing Lab, France) and 6 hematology on Vet Test 8008 (IDEXX, USA). Data from 105 dogs (52 males and 53 females) for hematology and 113 dogs (37 males and 76 females) for chemistry were used to determine reference intervals using the parametric, nonparametric and bootstrap methods. Prior to analysis, all parameters were tested for normal distribution using Anderson-Darling criterion. Of the 9 biochemical analytes, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatinine, total protein, and glucose concentrations did not fit normal distribution for both original and transformed data. All but eosinophil count satisfied normal distribution for either original or transformed data. Parametric method can be used for original cholesterol concentrations, RBC, WBC, and neutrophil counts. This technique can also be used for power-transformed values of blood urea nitrogen concentrations and for logarithm of lymphocyte and monocyte counts. Non-parametric or bootstrap method was the preferred choice for the remaining 7 biochemical parameters and eosinophil count as they did not follow normal distributions. All three statistical techniques performed in similar reference intervals. When establishing reference intervals for clinical laboratory data, it is essential to assess the distribution of the original data to increase the accuracy of the interval, and non-parametric or bootstrap methods are of alternative for the data that do not fit normal distribution.

• 대한치과기공학회지
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• 제42권1호
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• pp.17-25
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• 2020

Purpose: The purpose of this study was to evaluate and compare the accuracy of definitive casts that are fabricated from digital intraoral impression and conventional impression technique. Methods: A master model(ANNA-4, Frasaco GmbH, Tettnang, Germany) with the prepared upper full arch tooth was used. Conventional impression and then stone model(n=10) were produced from this master model, and on the other hands, digital impressions were made with the CS-3600 intraoral scanner(n=10). Six linear measurements were recorded between landmarks, directly on each of the stone models on two occasions by a single examiner. Measurements were made with a digital caliper to the nearest 0.01mm from manual models and with the software(Delcam PowerSHAPE) from the virtual models. The t-student test for paired samples and intraclass correlation coefficient(ICC) were used for statistical analysis. Results: The measurement of two methods showed good reliability. The ICC of the two models were 0.88~0.91(stone model) and 0.94~0.99(digital model). The mean differences to master model for stone model and digital model were 0.10~0.14mm, and 0.14~0.20mm, respectively. Conclusion: The definitive casts obtained with digital intraoral technique model had significantly larger dimensions as compared to those of the stone model. However, the differences to the master model detected appear to provide enough accuracy and reliability for clinical application.

• 응용통계연구
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• 제20권1호
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• pp.183-194
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• 2007

이 논문에서는 두 독립인 이항 확률의 비교에서 이항 확률 중 하나 또는 모두가 0.05보다 작을 경우의 두 확률의 비교에 대한 표본수 계산의 문제를 다루었다. Whitte-more(1981)는 여러 공변량에 근거한 로지스틱 회귀를 이용하여 극소 확률의 경우에 대한 수정 표본수 공식을 제안하였다. 이를 독립된 비율의 비교에 적용하여 이로부터 계산한 표본수는 일반적으로 많이 사용하는 근사 정규 방법, 특히 극소 비율의 비교에 대한 방법이 아닌 근사 정규 방법의 표본수 보다도 훨씬 큰 표본수를 제시하고 있다. 그러므로, 응용분야의 통계인들은 극소 반응 확률에 근거한 임상 시험을 계획할 경우 계획의 단계에서 의도하는 검정력을 확보하기 위해 교과서에 제시된 표본수 공식이나 부표에 의존한다면 위험할 수 있음을 이 논문의 결과가 말해 주고 있다.

• 대한조선학회논문집
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• 제60권2호
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• pp.95-109
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• 2023

In the 4th industrial revolution, changes in the technological paradigm have had a direct impact on the maintenance system of ships. The 2-stroke low speed engine system integrates with the core equipment required for propulsive power. The Condition Based Management (CBM) is defined as a technology that predictive maintenance methods in existing calender-based or running time based maintenance systems by monitoring the condition of machinery and diagnosis/prognosis failures. In this study, we have established a framework for CBM technology development on our own, and are engaged in engineering-based failure analysis, data development and management, data feature analysis and pre-processing, and verified the reliability of failure mode DB using LSTM algorithms. We developed various simulated failure mode scenarios for 2-stroke low speed engine and researched to produce data on onshore basis test_beds. The analysis and pre-processing of normal and abnormal status data acquired through failure mode simulation experiment used various Exploratory Data Analysis (EDA) techniques to feature extract not only data on the performance and efficiency of 2-stroke low speed engine but also key feature data using multivariate statistical analysis. In addition, by developing an LSTM classification algorithm, we tried to verify the reliability of various failure mode data with time-series characteristics.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권3호
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• pp.428-451
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• 2010

Traffic matrix-based anomaly detection and DDoS attacks detection in networks are research focus in the network security and traffic measurement community. In this paper, firstly, a new type of unidirectional flow called IF flow is proposed. Merits and features of IF flows are analyzed in detail and then two efficient methods are introduced in our DDoS attacks detection and evaluation scheme. The first method uses residual variance ratio to detect DDoS attacks after Recursive Least Square (RLS) filter is applied to predict IF flows. The second method uses generalized likelihood ratio (GLR) statistical test to detect DDoS attacks after a Kalman filter is applied to estimate IF flows. Based on the two complementary methods, an evaluation formula is proposed to assess the seriousness of current DDoS attacks on router ports. Furthermore, the sensitivity of three types of traffic (IF flow, input link and output link) to DDoS attacks is analyzed and compared. Experiments show that IF flow has more power to expose anomaly than the other two types of traffic. Finally, two proposed methods are compared in terms of detection rate, processing speed, etc., and also compared in detail with Principal Component Analysis (PCA) and Cumulative Sum (CUSUM) methods. The results demonstrate that adaptive filter methods have higher detection rate, lower false alarm rate and smaller detection lag time.