• 한국수자원학회논문집
• /
• 제52권1호
• /
• pp.83-96
• /
• 2019

하천수사용 관리를 적정하게 관리하기 위해서는 객관적인 하천수사용량 자료가 수집되어야 한다. 그러나, 하천수 사용자의 취수여건을 고려하여 유량계 외에 수문조작 등의 간접적인 계측방법을 인정하고 있고, 사용자의 자발적인 보고에 의존함에 따라 자료의 객관화가 어려운 실정이다. 이에 한강홍수통제소에서는 농업용수 사용 비중이 커 하천유량 파악이 어려운 만경강의 고산~봉동 수위관측소 구간에 위치한 어우보 취수로에 V-ADCP를 이용한 계측시설을 설치 및 운영하고 있다. 본 연구에서는 V-ADCP로 측정된 유속을 이용하여 실시간 하천수사용량 산정을 위한 유속분포법의 적용성을 평가하였다. 이를 위해 Chiu의 2차원 유속분포식의 매개변수 민감도를 분석하고, 실측유량 자료에 기초한 최적 매개변수를 산정하였다. 또한 수위-유량관계법, 지표유속법과 비교 평가하여 유속분포법의 특성을 분석하였다.

• 천문학회보
• /
• 제44권1호
• /
• pp.52.3-52.3
• /
• 2019

We investigate a relative contribution from short to long-term flaring rate to predicting M and X-class flare probabilities. In this study, we consider magnetic parameters summarizing distribution and non-potentiality by Solar Dynamics Observatory/Helioseimic and Magnetic Imager and flare list by Geostationary Operational Environmental Satellites. A short-term rate is the number of major flares that occurred in an given active region (AR) within one day before the prediction time. A mid-term rate is a mean flaring rate from the AR appearance day to one day before the prediction time. A long-term rate is a rate determined from a relationship between magnetic parameter values of ARs and their flaring rates from 2010 May to 2015 April. In our model, the predicted rate is given by the combination of weighted three rates satisfying that their sum of the weights is 1. We calculate Brier skill scores (BSSs) for investigating weights of three terms giving the best prediction performance using ARs from 2015 April to 2018 April. The BSS (0.22) of the model with only long-term is higher than that with only short-term or mid-term. When short or mid-term are considered additionally, the BSSs are improved. Our model has the best performance (BSS = 0.29) when all three terms are considered, and their relative contribution from short to long-term rate are 19%, 23%, and 58%, respectively. This model seems to be more effective when predicting active solar ARs having several major flares.

• 국제강구조저널
• /
• 제18권4호
• /
• pp.1440-1463
• /
• 2018

The Wagner coefficient is a key parameter used to describe the inelastic lateral-torsional buckling (LTB) behaviour of the I-beam, since even for a doubly-symmetric I-section with residual stress, it becomes a monosymmetric I-section due to the characteristics of the non-symmetrical distribution of plastic regions. However, so far no theoretical derivation on the energy equation and Wagner's coefficient have been presented due to the limitation of Vlasov's buckling theory. In order to simplify the nonlinear analysis and calculation, this paper presents a simplified mechanical model and an analytical solution for doubly-symmetric I-beams under pure bending, in which residual stresses and yielding are taken into account. According to the plate-beam theory proposed by the lead author, the energy equation for the inelastic LTB of an I-beam is derived in detail, using only the Euler-Bernoulli beam model and the Kirchhoff-plate model. In this derivation, the concept of the instantaneous shear centre is used and its position can be determined naturally by the condition that the coefficient of the cross-term in the strain energy should be zero; formulae for both the critical moment and the corresponding critical beam length are proposed based upon the analytical buckling equation. An analytical formula of the Wagner coefficient is obtained and the validity of Wagner hypothesis is reconfirmed. Finally, the accuracy of the analytical solution is verified by a FEM solution based upon a bi-modulus model of I-beams. It is found that the critical moments given by the analytical solution almost is identical to those given by Trahair's formulae, and hence the analytical solution can be used as a benchmark to verify the results obtained by other numerical algorithms for inelastic LTB behaviour.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2017년도 학술발표회
• /
• pp.45-45
• /
• 2017

상이한 자연현상으로 발생된 자료들은 때때로 통계적으로 다른 특성을 가지는 경우가 있다. 이런 자료들은 다른 두 개 이상의 모집단에서 자료가 발생한 것으로 가정할 수 가 있다. 기존에 널리 사용되어온 분포형 모형의 경우 단일한 모집단으로부터 자료가 발생한다는 가정하에서 개발된 모형들로 위에서 언급한 자료들을 적절히 모의할 수 없다. 이런 상이한 모집단에서 발생된 자료를 모형화 하기 위해서 혼합분포모형(mixture distribution)이 개발되었다. 홍수나 가뭄 등과 같은 극치 사상의 경우 다양한 자연현상들로부터 발생하기에 혼합분포모형을 적용할 경우 보다 정확한 모의가 가능하다. 혼합분포모형은 두 개 이상의 비혼합분포모형들을 가중합하여 만들어진다. 혼합 분포모형의 형태로 인하여 기존의 분포형 모형의 매개변수 추정 모형으로 널리 사용되던 최우도법 (maximum likelihood method), 모멘트법(method of moment), 확률가중모멘트법 (probability weighted moment method) 등을 이용하여 혼합분포모형의 매개변수를 추정하는 것이 용이 하지 않다. 혼합분포모형의 매개변수 추정 방법으로는 Expectation-Maximization (EM) 알고리즘, Meta-Heuristic Maximum Likelihood (MHML) 방법, Markov Chain Monte Carlo (MCMC) 방법 등이 적용되고 있다. 현재까지 수자원 분야에서 사용되는 극치 자료를 혼합분포모형을 이용하여 모의할 때 매개변수 추정방법에 따른 특성에 대한 연구가 진행되지 않았다. 본 연구에서는 우리나라 연최대강우량 자료를 이용하여 혼합분포모형의 매개변수 추정방법 (EM 알고리즘, MHML 방법, MCMC 방법) 들의 특성들을 비교 분석하였다. 혼합분포모형으로는 Gumbel-Gumbel 혼합분포 모형을 적용하였다. 본 연구의 결과는 향후 혼합분포모형을 이용한 연구에 좋은 기초자료로 사용될 수 있을 것으로 판단된다.

• 드라이브 ㆍ 컨트롤
• /
• 제18권1호
• /
• pp.1-8
• /
• 2021

This paper presents research on methods for the reduction of forklifts' noise level for the increased comfort and safety of its operator. A cooling fan with a high air volume flow rate installed in the forklift acts as an important design parameter which efficiently cools the heat exchanger system, helping to transfer internal heat from the engine room to the outdoors with both transmitted and diffracted opening noises. The cooling fan contributes significantly to both the forklift's emitted sound power and the operator room's noise level, thereby necessitating research on the forklift's reduction of acoustic power level and transmission. A noise analysis for various fan models with a biomimetic design based on eagle-wing geometry was conducted. In addition to the acoustic power generation, the aerodynamic performance of the cooling blade is also strongly influenced by the design of airfoil distribution, thereby requiring optimization. The cooling fans were fabricated and installed in the forklift in order to check the efficacy of the forklift engine's cooling, and the final version of the fan was measured for its ability to lower acoustic power level and cool the engine room. This study explains the aerodynamic and acoustic features of the designed fans with the use of BEM analysis and forklift test results.

• 디지털융복합연구
• /
• 제19권2호
• /
• pp.175-182
• /
• 2021

본 연구에서는 제조 및 유통 중소기업을 대상으로 ITO 실행에서 발생할 수 있는 리스크가 기업성과에 어떠한 영향을 미치는지에 대해 실증분석하였다. ITO로 비용절감이나 경쟁력을 확보하려는 중소기업들이 ITO의 리스크를 파악하고 분석하여 기업성과를 향상시키기 위한 목적으로 연구를 진행하였다. 설문조사방법으로 분석하기 위해 전략 리스크, 기술 리스크, 재무 리스크를 독립변수로 선정하였다. 그리고 관계 리스크를 매개변수로 선정하였고, 기업성과를 종속변수로 선정하여 경로분석을 실시하였다. 분석결과 독립변수로 투입된 변수들은 기업성과에 간접효과와 총효과가 있는 것으로 나타났다. 이는 전략 및 기술 리스크와 재무 리스크의 인식수준이 높을수록 관계리스크수준도 높아지게 되고, 따라서 기업성과에도 긍정적인 영향을 미치게 되는 것으로 해석할 수 있다. 향후 더 많고 다양한 리스크 요인들의 분석을 통해 기업성과를 개선할 수 있을 것으로 기대한다.

• Earthquakes and Structures
• /
• 제20권1호
• /
• pp.71-86
• /
• 2021

This paper focuses on the development and assessment of the expected damage for the rocking response of rigid anchored blocks, with irregular geometry and non-uniform mass distribution, considering the site conditions and the seismicity of Mexico City. The non-linear behavior of the restrainers is incorporated to evaluate the pure tension and tension-shear failure mechanisms. A probabilistic framework is performed covering a wide range of block sizes, slenderness ratios and eccentricities using physics-based ground motion simulation. In order to incorporate the uncertainties related to the propagation of far-field earthquakes with a significant contribution to the seismic hazard at study sites, it was simulated a set of scenarios using a stochastic summation methods of small-earthquakes records, considered as Empirical Green's Function (EGFs). As Engineering Demand Parameter (EDP), the absolute value of the maximum block rotation normalized by the body slenderness, as a function of the peak ground acceleration (PGA) is adopted. The results show that anchorages are more efficient for blocks with slenderness ratio between two and three, while slenderness above four provide a better stability when they are not restrained. Besides, there is a range of peak intensities where anchored blocks located in soft soils are less vulnerable with respect to those located in firm soils. The procedure used in here allows to take decisions about risk, reliability and resilience assessment of different types of contents, and it is easily adaptable to other seismic environments.

• 한국정보통신학회논문지
• /
• 제24권9호
• /
• pp.1215-1223
• /
• 2020

최근 서울 경기를 비롯한 전국에서 국지성 집중호우, 태풍 등 악천후 관련 자연재해가 증가함에 따라 이에 대한 방재 및 물관리 대책이 필요한 실정이다. 이러한 수재해를 관측하기 위해 사용되는 우량계는 지상의 강우를 연속적·직접적으로 측정할 수 있는 장점이 있는 반면, 우량계 미설치 영역에 대한 공간적인 강우 분포를 정확하게 제공할 수 없다. 이러한 문제를 해결하고자 강수의 공간분포를 측정할 수 있는 전자파 기반 센서인 전파강수계(EWRG, Electromagnetic Wave Rain Gauge)를 개발하였다. 본 논문에서는 전파강수계의 FPGA 기반 신호처리 설계 방법을 제안한다. 전파강수계의 신호처리는 크게 LFM 파형의 ADC 및 DDC와 펄스압축, 상관 계수 및 강수 파라미터 산정으로 설계하였다. 본 연구를 통해 LFM 파형과 펄스압축 신호를 이론적으로 분석하였으며, 전파강수계 신호처리 설계를 위해서 FPGA 기반의 신호처리 설계 및 검증을 수행하였다.

• 동의생리병리학회지
• /
• 제34권4호
• /
• pp.184-190
• /
• 2020

This study was performed to find antibacterial substances contained in Scutellariae Radix (SR) using a systems pharmacological analysis method and to establish an effective strategy for the prevention and treatment of infectious diseases. Analysis of the main active ingredients of SR was performed using Traditional Chinese Medicine Systems Pharmacology (TCMSP) Database and Analysis Platform. 36 active compounds were screened by the parameter values of Drug-Likeness (DL), Oral Bioavailability (OB), and Caco-2 permeability (Caco-2), which were based on the drug absorption, distribution, metabolism, and excretion indicators. The UniProt database was used to obtain information on 159 genes associated with active compounds. The main active compounds with antibacterial effects were wogonin, β-sitosterol, baicalein, acacetin and oroxylin-A. Target proteins associated with the antibacterial action were chemokine ligand 2, interleukin-6, tumor necrosis factor, caspase-8,9 and mitogen-activated protein kinase 14. In the future, systems pharmacological analysis of traditional medicine will be able to make it easy to find the important mechanism of action of active substances present in natural medicines and to optimize the efficacy of medicinal effects for combinations of major ingredients to help treat certain diseases.

• 복식문화연구
• /
• 제29권4호
• /
• pp.554-571
• /
• 2021

The purpose of this study is to investigate the mediating effect of trust when a media broadcaster (such as a disc jockey [DJ]) acting as an information source and the content they provide during live commerce streaming affect acceptance intention. Live commerce is increasing rapidly, offering a new fashion distribution channel by supplementing possible shortcomings of existing online shopping. Data was collected for the empirical study from female consumers in their 20s who actively accepted fashion technology. Statistical analysis of the data was conducted using IBM SPSS Macro Process 3.5. First, the reliability and validity of the variables for information source characteristics, content informativeness, trust, and acceptance intention were verified, and each variable was confirmed as a single factor. Bootstrap analysis was performed using Macro Process Model 4 to reveal the effects of information source characteristics and content informativeness on acceptance intention. As a result of analyzing the mediating effect for each path model with trust as a parameter, it was found that both the direct and indirect effects of the mediating path were significant. This result means that the characteristics of information sources and content informativeness are partially mediated by trust. Therefore, to promote consumer behavior in a live commerce shopping environment, it is necessary to enhance trust. This can be achieved by a media broadcaster with fashion expertise to increase the perception of the attractiveness of the information source and to improve the usefulness of the fashion information being delivered.