• 항공우주시스템공학회지
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• 제16권3호
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• pp.1-9
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• 2022

본 연구에서는 MDO 프레임워크 개발을 위하여 다양한 준경험적 방법에 근거한 해석적 방법으로 경비행기인 창공-91의 비행운동 특성 파라미터를 추출하고 비행시험 방법을 기준으로 비교하여 평가하였다. 비교 대상의 준경험적 분석 방법은 Perkins 방법, McCormick 방법, 그리고 Smetana 방법이며, 각각의 방법을 통하여 주요 안정성/조종성 미계수와 동안정 계수를 산출하였다. 이에 대한 비교 기준은 비행시험을 수행하여 취득한 데이터로부터 출력오차방법을 활용하여 비행운동 미계수와 동안정 계수를 추출하였다. 아울러 경비행기의 비행특성을 우리나라 국토교통부의 항공기기술기준(KAS, Korean Airworthiness Standard)의 항목과 미 군용의 MIL-F-8785C의 기준으로 분석하여 평가하였다.

• 한국지반신소재학회논문집
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• 제10권4호
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• pp.61-70
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• 2011

본 연구에서는 TBM의 관입속도 예측에 대한 경험적 모델을 비교하기 위하여 현장사례를 이용하여 관입속도를 예측하였으며, 예측결과와 시공 시의 실측치를 비교 분석하여 합리적인 모델을 평가하였다. 관입속도 예측은 일축압축강도를 이용한 모델과 암석의 특성 및 TBM의 장비 특성을 고려한 모델로 적용하였다. 사례현장은 대부분 편마암으로 구성되어 있으며, 절리가 발달되어 약선대가 존재하기 때문에 암석의 일축압축강도가 불규칙적으로 나타났다. 일축압축강도를 이용한 예측결과에서 Graham(1976)의 모델은 낮은 강도의 경우, 비현실적인 예측결과가 나타나는 것으로 분석되었다. 평균 관입율을 이용한 각 모델들의 신뢰성을 분석한 결과, 암석의 특성 및 TBM 기계적 특성을 합리적으로 반영한 NTNU 모델(1998)이 가장 높은 것으로 확인되었다. 그러나 실측치와 비교한 결과에서는 일축압축강도를 바탕으로 예측하는 Tarkoy의 모델(1986)이 사례현장의 특성과 일치하는 것으로 분석되었다. 즉, TBM의 관입속도 예측 시에는 대상 암종, 지질특성 및 TBM의 장비 특성을 모두 고려하여 다양한 모델을 이용한 합리적인 예측이 수행되어야 한다.

• Gut and Liver
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• 제12권6호
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• pp.648-654
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• 2018

Background/Aims: Dual priming oligonucleotide-based multiplex polymerase chain reaction (DPO-based PCR) can detect the presence of clarithromycin resistance without culture. The aim of this study was to investigate the cost-effectiveness of DPO-based PCR for Helicobacter pylori eradication. Methods: From 2015 to 2016, medical records of patients who received H. pylori eradication therapy were analyzed. Patients were divided into two groups: tailored group patients who were treated based on DPO-based PCR and empirical group patients. Eradication rate and medical cost, including diagnostic tests, eradication regimens, and $^{13}C$-urea breath tests, were compared between the two groups. Cost for one successful eradication was calculated in each group. The expected cost of eradication for empirical treatment was investigated by varying the treatment duration and eradication rate. Results: A total of 527 patients were analyzed (tailored group 208, empirical group 319). The eradication success rate of the first-line therapy was higher in the tailored group compared to that in the empirical group (91.8% vs 72.1%, p<0.01). The total medical cost for each group was $114.8{\pm}14.1U.S.$ dollars (USD) and $85.8{\pm}24.4USD$, respectively (p<0.01). The total medical costs for each ultimately successful eradication in the tailored group and in the empirical group were 120.0 USD and 92.4 USD, respectively. The economic modeling expected cost of a successful eradication after a 7- or 14-day empirical treatment was 93.8 to 111.4 USD and 126.3 to 149.9 USD, respectively. Conclusions: Based on economic modeling, the cost for a successful eradication using DPO-based PCR would be similar or superior to the expected cost of a successful eradication with a 14-day empirical treatment when the first-line eradication rate is ${\leq}80%$.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.154-157
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• 1999

Microwave polarimetric backscattering from a wet soil surface had been measured using a Ku-band polarimetric scatterometer at the incidence angles ranging from 10$^{\circ}$ to 70$^{\circ}$ Since the accurate target parameters as well as the radar parameters are necessary for radar scattering modeling, a complete and accurate set of ground truth data were also collected, from which accurate measurements were made of the rms height, correlation length, and dielectric constant. The measured polarimetric backscattering coefficients (vv-, hh-, vh-, hv-polarizations) were compared with theoretical models and empirical models. A new semi-empirical model for microwave polarimetric radar backscattering from bare soil surfaces was developed using polarimetric radar measurements and the knowledge based on the theoretical and numerical solutions. The model was found to yield very good agreement with the backscattering measurements of this study.

• ETRI Journal
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• 제44권5호
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• pp.826-836
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• 2022

Signal decomposition is a computational technique that dissects a signal into its constituent components, providing supplementary information. In this study, the capability of two common signal decomposition techniques, including wavelet-based and empirical mode decomposition, on preterm birth classification was investigated. Ten time-domain features were extracted from the constituent components of electrohysterogram (EHG) signals, including EHG subbands and EHG intrinsic mode functions, and employed for preterm birth classification. Preterm birth classification and anticipation are crucial tasks that can help reduce preterm birth complications. The computational results show that the preterm birth classification obtained using wavelet-based decomposition is superior. This, therefore, implies that EHG subbands decomposed through wavelet-based decomposition provide more applicable information for preterm birth classification. Furthermore, an accuracy of 0.9776 and a specificity of 0.9978, the best performance on preterm birth classification among state-of-the-art signal processing techniques, were obtained using the time-domain features of EHG subbands.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2009년도 추계학술발표대회
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• pp.17-18
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• 2009

This paper shows our empirical comparison result between two retargetable compilers, GCC and SoarGen. SoarGen is our retargetable compiler. According to our experimental result, using SoarGen for targeting ODALRISC is proved to be easier and faster than using GCC. The average retarget time of the SoarGen is much less than the retarget time of the GCC.

• Geomechanics and Engineering
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• 제3권3호
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• pp.189-206
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• 2011

Amplification based on empirical relations is widely used for seismic microzonation of urban centers. Amplifications are used to represent the site effects of a particular soil column. Many empirical correlations are available to estimate the amplification of seismic waves. These correlations are based on the ratio of shear wave velocity of foundation/rock to soil velocity or 30 m equivalent shear wave velocity ($Vs^{30}$) and are developed considering deep soil data. The aim of this work is to examine the applicability of available amplification relations in the literature for shallow engineering bedrock sites by carrying out site response studies. Shear wave velocity of thirteen sites having shallow engineering bedrock have been selected for the study. In these locations, the depth of engineering bedrock (> 760 ${\pm}$ 60 m/s) is matched with the drilled bore hole. Shear wave velocity (SWV) has been measured using Multichannel Analysis of Surface Wave survey. These sites are classified according to the National Earthquake Hazards Reduction Program (NEHRP) classification system. Amplifications for an earthquake are arrived for these sites using empirical relations and measured SWV data. Site response analysis has been carried out in SHAKE using SWV and using synthetic and real earthquake data. Amplification from site response analysis and empirical relations are compared. Study shows that the amplification arrived using empirical relations does not match with the site response amplification. Site response amplification is much more than empirical values for same shear wave velocity.

• Wind and Structures
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• 제19권3호
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• pp.233-247
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• 2014

Vortex-induced oscillation is a type of aeroelastic phenomenon, to which extended structures such as long-span bridges are most susceptible. The vortex-induced vibration (VIV) behaviors of a concerned bridge were investigated conventionally in virtue of wind tunnel tests on string-mounted sectional models. This necessitates the building of a linkage between the response of the sectional model and that of the prototype structure. Although many released literatures have related to this issue and provided suggestions, there is a lack of consistency among them. In this study, some theoretical models describing the vortex-induced structural motion, including the linear empirical model, the nonlinear empirical model and the modified (or generalized) nonlinear empirical model, are firstly reviewed. Then, the concept of equivalent mass density is introduced based on the principle that an equal input of energy should result in identical structural amplitudes. Based on these, the theoretical linkages between the amplitude of a section model and that corresponding to the prototype bridge are discussed with different analytical models. Theoretical derivation indicates that such connections are dependent mainly on two factors, one is the presupposed shape of deformation, and the other is the theoretical VIV model employed. The theoretical analysis in this study shows that, in comparison to the nonlinear empirical models, the linear one can result in obvious larger estimations of the full bridges' responses, especially in cases of cable-stayed bridges.

• Communications for Statistical Applications and Methods
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• 제18권2호
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• pp.245-255
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• 2011

자료의 분포변화를 검정하는 비모수적 방법으로 경험분포함수를 이용하거나 확률밀도함수 추정량을 이용하는 두 가지 방법을 고려할 수 있다. 이 논문에서는 분포변화 검정을 위한 두가지 방법을 자세히 살펴보고 기존 연구의 결과를 정리한다. 여러 확률모형을 가정하고 분포변화 검정에 대한 모의 실험을 실시하여 두 방법에 대한 이론적 극한 성질이잘 성립하는가를 살펴본다. 검정력 비교를 통하여 모형에 따른 적절한 변화점 분석 방법을 알아본다.

• 한국공간구조학회논문집
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• 제19권2호
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• pp.101-108
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• 2019

In this paper, the characteristic of intrinsic mode function(IMF) and its orthogonalization of ensemble empirical mode decomposition(EEMD), which is often used in the analysis of the non-linear or non-stationary signal, has been studied. In the decomposition process, the orthogonal IMF of EEMD was obtained by applying the Gram-Schmidt(G-S) orthogonalization method, and was compared with the IMF of orthogonal EMD(OEMD). Two signals for comparison analysis are adopted as the analytical test function and El Centro seismic wave. These target signals were compared by calculating the index of orthogonality(IO) and the spectral energy of the IMF. As a result of the analysis, an IMF with a high IO was obtained by GSO method, and the orthogonal EEMD using white noise was decomposed into orthogonal IMF with energy closer to the original signal than conventional OEMD.