• 한국작물학회지
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• 제46권3호
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• pp.195-201
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• 2001

본 연구는 광안벼를 공시하여 지연일장의 인공기상실(21$^{\circ}C$ 및 24$^{\circ}C$)과 포장 조건에서 파종기(최초 파종 일 4월25일, 최종 파종일 6월 5일) 이동에 따른 온도와 일장 변화가 출엽 및 출수기 변화에 미치는 영향을 검토하여, 일장에 따른 최종엽수 추정모델을 설정하였으며, 이 모델과 온도에 따른 출엽속도 모델을 결합하여 출수기 예측모델을 설정하여 모델의 출수기 추정 정확도를 검증하였다. 1. 포장에서는 4월 25일 이후 파종기가 늦을수록 생육기간 중 평균기온은 높아진 반면, 포장과 인공기상실 양 조건에서 일장감응기간(6엽기부터 유수분화기)중의 평균일장은 짧아졌다. 이에 따라 일장만 관여한 인공기상실에 비해 온도와 일장이 함께 관여한 포장에서 파종시기에 따른 출수소요일수 단축정도가 크게 나타났다. 2. 일장감응기간의 일장이 길어짐에 따라 최종엽수(FNL)가 증가하였으며, 이 관계는 다음과 같은 Rational 함수로 잘 표현이 되었고($R^2$=0.98),이를 광안벼의 최종엽수 추정모델로 설정하였다. 여기서 D는 일장이며, a,b,c는 상수로서 각각 14.694, -0.992, -0.068로 추정되었다. 3.온도에 따른 출엽속도 모델과 일장에 따른 최종엽수 모델로 구성된 출수기 예측 모델을 구성하였으며, 모델 설정에 이용되지 않은 포장실험 자료를 이용하여 검증한 결과 추정된 출수기는 예측오차가 1-2일로 추정 정확도가 높았다.

• 한국산학기술학회논문지
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• 제18권6호
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• pp.576-584
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• 2017

교통수요 예측 결과는 교통계획 및 운영과 같은 의사결정 과정에서 매우 주요하게 작용되고 있다. 교통수요 예측 시 적용되는 기존 교통수요 예측 4단계 모형은 지정된 기점과 종점 간의 통행만을 대상으로 하며 모형의 특성상 접근성 향상에 따라 유발되는 수요는 고려하지 못하고 있다. 따라서 본 연구는 기존 모형의 한계를 보완하고 모형의 추정력 및 신뢰성을 제고하기 위해 접근성을 반영한 전국 지역 간 통행발생 및 통행분포모형 개발에 목적을 두었다. 접근성을 반영한 통행발생 및 통행분포모형 정산 결과, 접근성 계수의 부호는 양(+)의 값으로 추정되었다. 통행목적 중 업무통행은 타 목적통행에 비해 외부요소의 제약에 가장 둔감한 것으로 나타났으며 여가통행은 통행비용에 가장 민감한 것으로 나타났다. 정산된 통행발생 및 통행분포모형을 관측자료 와의 비교를 통해 검증한 결과, 접근성을 반영한 모형의 가중평균(weighted average) 오차율(%), RMSE(Root Mean Square Error), 총 오차량(total error)등이 기존 모형에 비해 감소하는 것으로 나타남에 따라 모형의 추정력 및 신뢰성이 개선됨을 확인하였다.

• 전기학회논문지
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• 제65권11호
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• pp.1868-1878
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• 2016

This paper proposes a novel velocity estimator for long-term underwater navigation of autonomous underwater vehicles(AUVs). Provided that an external position fix is not given, a viable goal in designing a underwater navigation algorithm is to reduce the divergence rate of position error only using the sporadic velocity information obtained from Doppler velocity log(DVL). For such case, the performance of underwater navigation eventually depends on accuracy and reliability of external velocity information. This motivates us to devise a velocity estimator which can drastically enhance the navigation performance even when the DVL measurement is unavailable. Incorporating the Gertler-Hagen hydrodynamics model of an AUV with the measurement models of velocity and depth sensors, the velocity estimator design problem is resolved using the extended Kalman filter. Different from the existing methods in which an AUV simulator is regarded as a virtual sensor, our approach is less sensitive to the model uncertainty often encountered in practice. This is because our velocity filter estimates the simulator errors with sensor aids and furthermore compensates these errors based on the indirect feedforward manner. Through the simulations for typical AUV navigation scenarios, the effectiveness of the proposed scheme is demonstrated.

• Genomics & Informatics
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• 제5권3호
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• pp.102-106
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• 2007

Radiofrequency (RF) radiation at the frequency of mobile phones has been not reported to induce cellular responses in in vitro and in vivo models. We exposed HEI-OC1, conditionally-immortalized mouse auditory cells, to RF radiation to characterize cellular responses to 1763 MHz RF radiation. While we could not detect any differences upon RF exposure, whole-genome expression profiling might provide the most sensitive method to find the molecular responses to RF radiation. HEI-OC1 cells were exposed to 1763 MHz RF radiation at an average specific absorption rate (SAR) of 20 W/kg for 24 hr and harvested after 5 hr of recovery (R5), alongside sham-exposed samples (S5). From the whole-genome profiles of mouse neurons, we selected 9 differentially-expressed genes between the S5 and R5 groups using information gain-based recursive feature elimination procedure. Based on support vector machine (SVM), we designed a prediction model using the 9 genes to discriminate the two groups. Our prediction model could predict the target class without any error. From these results, we developed a prediction model using biomarkers to determine the RF radiation exposure in mouse auditory cells with perfect accuracy, which may need validation in in vivo RF-exposure models.

• Steel and Composite Structures
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• 제25권1호
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• pp.79-92
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• 2017

Initial damage to a stud due to corrosion, fatigue, unexpected overloading, a weld defect or other factors could degrade the shear capacity of the stud. Based on typical push-out tests, a FEM model and theoretical formulations were proposed in this study. Six specimens with the same geometric dimensions were tested to investigate the effect of the damage degree and location on the static behavior and shear capacity of stud shear connectors. The test results indicated that a reduction of up to 36.6% and 62.9% of the section area of the shank could result in a dropping rate of 7.9% and 57.2%, respectively, compared to the standard specimen shear capacity. Numerical analysis was performed to simulate the push-out test and validated against test results. A parametrical study was performed to further investigate the damage degree and location on the shear capacity of studs based on the proposed numerical model. It was demonstrated that the shear capacity was not sensitive to the damage degree when the damage section was located at 0.5d, where d is the shank diameter, from the stud root, even if the stud had a significant reduction in area. Finally, a theoretical formula with a reduction factor K was proposed to consider the reduction of the shear capacity due to the presence of initial damage. Calculating K was accomplished in two ways: a linear relationship and a square relationship with the damage degree corresponding to the shear capacity dominated by the section area and the nominal diameter of the damaged stud. This coefficient was applied using Eurocode 4, AASHTO LRFD (2014) and GB50017-2003 (2003) and compared with the test results found in the literature. It was found that the proposed method produced good predictions of the shear capacity of stud shear connectors with initial damage.

• Genomics & Informatics
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• 제4권2호
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• pp.71-76
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• 2006

We have investigated biological responses to radiofrequency (RF) radiation in in vitro and in vivo models. By measuring the levels of heat shock proteins as well as the activation of mitogen activated protein kinases (MAPKs), we could not detect any differences upon RF exposure. In this study, we used more sensitive method to find the molecular responses to RF radiation. Jurkat, human T-Iymphocyte cells were exposed to 1763 MHz RF radiation at an average specific absorption rate (SAR) of 10 W/kg for one hour and harvested immediately (R0) or after five hours (R5). From the profiles of 30,000 genes, we selected 68 differentially expressed genes among sham (S), R0 and R5 groups using a random-variance F-test. Especially 45 annotated genes were related to metabolism, apoptosis or transcription regulation. Based on support vector machine (SVM) algorithm, we designed prediction model using 68 genes to discriminate three groups. Our prediction model could predict the target class of 19 among 20 examples exactly (95% accuracy). From these data, we could select the 68 biomarkers to predict the RF radiation exposure with high accuracy, which might need to be validated in in vivo models.

• 융합정보논문지
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• 제11권6호
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• pp.270-281
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• 2021

정보기술의 발달로 보험사기의 규모는 매년 급증하고 있고, 그 방법도 공모 형태로 조직화되고 고도화되고 있다. 이를 예측하고 검출하기 위한 다양한 형태의 예측모델이 연구되고 있지만 보험관련 정보는 매우 민감하여 공유와 접근에 위험이 높고 법적인 혹은 기술적인 제약이 많다. 이 논문에서는 최근 4차 산업 혁명의 등장으로 가장 각광받는 기술 중 하나인 블록체인을 기반으로 한 기계학습 보험사기 예측모델을 제안한다. 블록체인 기술을 활용하여 안전하고 신뢰받는 보험청구 정보 공유시스템을 실현하고, 보다 효율적이고 정확한 사기예측을 위하여 사회관계분석이론을 적용하여 각 관계에 가중치를 부여하고 기계학습 사기 예측패턴을 4단계로 나누어 제안하였다. 사기 가능성이 높은 보험청구건은 보다 앞선 단계에서 높은 예측 율로 검출되는 효과를 가지며 가능성이 낮은 청구 건은 사후에 참고하여 관리할 수 있도록 차등 적용하였다. 제안하는 모델의 중요 매커니즘은 이더리움(Ethereum) 로컬 네트워크를 구성하여 검증 하였고, 향후 보다 정교한 성능평가가 요구된다.

• 한국유체기계학회 논문집
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• 제10권2호
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• pp.7-15
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• 2007

A numerical procedure for optimizing the shape of three-dimensional channel with V-shaped ribs extruded on both walls has been carried out to enhance the turbulent heat transfer. The response surface based optimization is used as an optimization technique with Reynolds-averaged Wavier-stoked analysis. Shear stress transport (SST) turbulence model is used as a turbulence closure. Computational results for average heat transfer rate show good agreements with experimental data. The objective function is defined as a linear combination of heat transfer and friction loss-related terms with a weighting factor. Three dimensionless variables such as, rib pitch-to-rib height ratio, rib height-to-channel height ratio, and the attack angle of the rib are chosen as design variables. Nineteen training points obtained by D-optimal designs for three design variables construct a reliable response surface. In the sensitivity analysis, it is found that the objective function is most sensitive to the ratio of rib height-to-channel height ratio. And, optimal values of design variables have been obtained in a range of the weighting factor.

• 펄프종이기술
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• 제37권3호
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• pp.1-8
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• 2005

Increase in the utilization rate of recycled paper and closing level of papermaking system increased the problem associated with stickies that include decrease in process runnability and product quality. It is required to establish a process for removing the micro stickies to solve the problems associated with stickies. In this study, the application of flotation process as a method to remove micro stickies was examined. Model micro stickies (MMS) were prepared using microcrystalline cellulose (MCC) and pressure sensitive adhesives (PSA), and the influence of three nonionic surfactants on the removal efficiency of MMS from flotation process was examined. Also the effect of surfactants on the deposition of micro stickies that remaining in the papermaking wet end onto wire was examined. Removal efficiency of MMS by flotation was increased when the proportion of nonionic surfactant with propylene oxide (PO) type hydrophilic tail was increased and stock pH was 7. It was suggested that this nonionic surfactant minimized the increase of surface energy of hydrophobic MMS. The MMS with high hydrophobicity remaining in the papermaking system, however, would cause more serious deposition problems on papermaking wet end. Therefore, it is of great importance to increase the removal efficiency of MMS in flotation process for the prevention of papermaking system contamination caused by stickies deposition.

• 한국유체기계학회 논문집
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• 제19권4호
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• pp.5-12
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• 2016

In this study, a parametric study on a cavity as casing treatment of a centrifugal compressor has been conducted using three-dimensional Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model. Two kinds of cavity were applied at choke and surge conditions, respectively, in this work. Inlet and outlet port widths, angle of outlet port, and length of cavity were chosen as the geometric parameters and investigated to find their effects on the aerodynamic performances such as adiabatic efficiency at design mass flow rate and stall margin of the centrifugal compressor. It was found that the aerodynamic performances of the centrifugal compressor were affected considerably by the four geometric parameters. The adiabatic efficiency was hardly changed by the geometric parameters, excepts for the angle of outlet port. With an increase in the angle of outlet port, the adiabatic efficiency and the stall margin decreased. The stall margin was more sensitive to the outlet port width than to the other geometric parameters. And, with a decrease in the outlet port width, the stall margin increased by 2% compared to that of the reference.