• 한국조경학회지
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• 제33권2호
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• pp.71-82
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• 2005

A large scale of riverside rearrangement has been recently done in the major rivers in Korea. So inundation possibility in agricultural area closed by these rivers has been higher than the possibility a few years ago. However, land use in this area has not been adjusted to a change of this situation near the rivers. Therefore, when typhoon or heavy rain is happened on this area, it can cause a large damage in agricultural area. This study analyzed inundation potentiality in agricultural area at Ibang-myeon, Changnyeong-gun, Kyeongnam-province, Korea by using the logistic regression model and the piecewise regression model. The first thing we did was to transfer the inundation area per elevation to the accumulated inundation area per elevation. This accumulated inundation area per elevation as an distribution function could be described by the logistic regression model(LRM), and piecewise regression model(PRM) could make it much more accurate to analyze the inundation area per elevation. As a result, the regression models derived from LRM and PRM showed $R^2$ over 0.950. The models derived from LRM and PRM in Ibang-myeon noted that frequently inundated area(FIA) was shown up to 12.12m in elevation, and potentially inundated area(PIA) was shown up to 14.60m in elevation. In FIA, regular agricultural activity would be impossible. And It would be not easy to continue the regular agricultural activity in PIA. So, this land should be rearranged to be used for a buffer zone for ecosystem protection, landscape conservation and things like that in riverside.

• 한국지반신소재학회논문집
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• 제15권1호
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• pp.1-10
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• 2016

최근 해상풍력발전 단지 조성은 많은 양의 에너지를 창출할 수 있어 그 기대는 점차적으로 증가하고 있다. 특히 제주도는 풍황이 우수하여 해상풍력발전 시스템 운영을 위한 최적의 대상지이기는 하나, 화산활동에 의해 형성된 지형으로 육지부와 달리 현무암층 사이에 연약층인 화산쇄설물 및 공동이 불규칙하게 발달된 층상구조로 이루어져 있다. 이에 본 연구에서는 제주현무암의 p-y 곡선을 얻기 위한 수평재하시험을 실시하였다. 말뚝 수평재하시험중에 측정한 변형률 데이터로부터 p-y 곡선을 유도하기 위하여 수평변위(y)는 high order polynomial curve fitting 기법을 적용하고, 지반반력(p)은 piecewise cubic polynomial curve fitting 기법을 추천한다. 이는 지반반력을 계산하기 위하여 미분하는 과정에서 발생하는 에러를 최소화 할 수 있으므로 역해석을 통한 말뚝두부에서 하중-변위를 예측할 때 에러가 가장 작게 발생한다.

• 한국도로학회논문집
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• 제14권6호
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• pp.139-148
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• 2012

PURPOSES : The accuracy of travel time information is a key measure of effectiveness and reliability of advanced traveler information systems. This study aims at investigating drivers' perception on the acceptable level of information accuracy and their corresponding valuations. METHODS : A questionnaire survey was executed for collecting driver perception data to capture the expectation level of travel time information provided and their willingness to pay for the information. A Tobit model was adopted for exploring the relationship among the acceptable level, driver socioeconomic characteristics and travel attributes. Since drivers' willingness to pay for accurate travel time information can be different according to their travel lengths, a piecewise linear regression model was developed to capture the sensitivity of values of travel time information to travel length. RESULTS : The analysis results suggest that trip purpose and travel time are two dominant factors to determine drivers' acceptable level of travel time information. For business and short trips, drivers want more accurate information than for non-business and long trips. Drivers' willingness to pay for travel time information also varies depending on their incomes, trip purposes and travel lengths. The results also show that drivers' valuation of travel time information provided is sensitive to their travel length. For longer trips, drivers are less sensitive to travel time information and then put less value on the information provided. CONCLUSIONS : Censored nonlinear regression models are developed to estimate drivers' acceptable accuracy for travel time information and their valuation using questionnaire survey data. The findings on drivers perception to the required accuracy of travel time information and their corresponding willingness to pay can be used in the design and deployment of advanced traveler information system to improve its effectiveness and usefulness through high compliance.

• 전자공학회논문지
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• 제50권11호
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• pp.90-98
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• 2013

지역적 정합방법을 이용한 스테레오 시스템은 알고리즘의 특성상 하드웨어 설계가 용이하여 많이 사용되나 낮은 정합률로 인해 정확한 깊이 영상을 얻기 힘들기 때문에 많은 응용 분야에 사용하기에 제한이 있다. 본 논문에서 제안한 스테레오 시스템은 픽셀의 변화도(gradient)를 기반으로 한 적응적인 가중치 알고리즘을 이용하여 높은 정합 성능을 보이며 하드웨어로 설계하였을 때 실시간처리가 가능하다. 일반적으로 적응적인 가중치 윈도우를 적용할 경우 중간 결과를 재사용하기 불가능하지만 행, 열을 분리하여 처리함으로써 데이터를 재사용할 수 있고 따라서 처리성능이 개선되었다. 알고리즘에 필요한 지수 및 아크탄젠트 함수를 구현하기 위해 선형(PWL, piecewise linear) 및 계단(step) 함수 등으로 근사화한 뒤 에러를 분석하여 최선의 파라미터를 선택하였다. 제안한 구조는 실시간처리를 위하여 9개의 프로세서를 사용하여 병렬처리를 하였으며, 동부하이텍 0.18um 라이브러리로 합성하였을 경우 최대 동작주파수 350MHz(33 fps)와 424K 게이트의 하드웨어 복잡도를 나타내었다.

• 전자공학회논문지S
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• 제34S권2호
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• pp.112-120
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• 1997

The clamp mode (CM) forward zero voltage switching multi resonant converter (ZVS-MPC) with self-driven synchronous rectifier is studied. The loss at the synchronous rectification stage of the converter is analyzed using MOSFET piecewise linear model and is compared with the loss at the conventional schottky diode rectification stage of th econverter. From the results of the analysis, it is known that the use fo MOSFETs as a synchronous rectifier reduces the loss at the rectification stage overthe whole load range comparing the use of schottky diodes as a conventional rectifier in the converter. In order to verify the validit of the analysis, we have built a 33W(3.3V/10A) CM forward ZVS-MRC with self-driven synchronous rectifier, in which switching frequency is 1MHz, and tested. FRom the experimental results, it is known that the synchronous rectification achieved about 1W improvement in the loss at the rectification stage and about 3% in the efficiency at the converter as compared with the conventional schottky diode rectification.

• Communications for Statistical Applications and Methods
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• 제27권1호
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• pp.37-46
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• 2020

Recurrent event data frequently occur in clinical studies, demography, engineering reliability and so on (Cook and Lawless, The Statistical Analysis of Recurrent Events, Springer, 2007). Sometimes, two or more different but related type of recurrent events may occur simultaneously. In this study, our interest is to estimate the covariate effect on bivariate recurrent event times with zero inflations. Such zero inflation can be related with susceptibility. In the context of bivariate recurrent event data, furthermore, such susceptibilities may be different according to the type of event. We propose a joint model including both two intensity functions and two cure rate functions. Bivariate frailty effects are adopted to model the correlation between recurrent events. Parameter estimates are obtained by maximizing the likelihood derived under a piecewise constant hazard assumption. According to simulation results, the proposed method brings unbiased estimates while the model ignoring cure rate models gives underestimated covariate effects and overestimated variance estimates. We apply the proposed method to a set of bivariate recurrent infection data in a study of child patients with leukemia.

• Near Infrared Analysis
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• 제1권1호
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• pp.9-17
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• 2000

A variety of standardization methods between two near-infrared (NIR) spectrometers were investigated for the prediction of five constituents in trans-alkylation process. Spectra were collected by two different instruments (one is regarded as mater instrument, other on as slave instrument). Three well-known standardization methods of direct standardization (DS), piecewise direct standardization (PDS) and slope/bias correction of response variable were applied to trans-alkylation samples on the slave instrument. We have examined for a set of reliable standardization samples using smaller number of transfer samples in order to increase efficiency of standardization.

• 한국통계학회:학술대회논문집
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• 한국통계학회 2004년도 학술발표논문집
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• pp.243-248
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• 2004

The timings of two successive events of interest may not be measurable, instead it may be right censored or interval censored; this data structure is called doubly censored data. In the study of HIV, two such events are the infection with HIV and the onset of AIDS. These data have been analyzed by authors under the assumption that infection time and induction time are independent. This paper investigates the regression problem when two events arc modeled to allow the presence of a possible relation between two events as well as a subject-specific effect. We derive the estimation procedure based on Goetghebeur and Ryan's (2000) piecewise exponential model and Gauss-Hermite integration is applied in the EM algorithm. Simulation studies are performed to investigate the small-sample properties and the method is applied to a set of doubly censored data from an AIDS cohort study.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.455-460
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• 2000

Impact occurs when the vibration amplitude of a mechanical component exceeds a given clearance size. Examples of these mechanical systems include impact dampers, gears, link mechanism, rotor rub, and so on. The vibration due to impact has strong non-linear characteristics, which cannot be predicted by usual linear analysis. The designs of mechanical systems with impacts should be done on the basis of overall dynamic characteristics of the systems. In this paper, the nonlinear behaviors of a beam with a periodically moving support and a rigid stop are investigated numerically and experimentally. The beam vibration with impact is modeled by the equations of motion containing piecewise linear restoring forces and by the coefficient of restitution, respectively. Experimental and numerical results show jump phenomena and higher-harmonic vibrations. The effects between the increase of stiffness during impact and the coefficient of restitution are investigated through the comparison of the experimental and numerical results.

• 전자공학회논문지A
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• 제31A권2호
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• pp.18-25
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• 1994

In this papaer, the input impedance of the rectangular microstrip patch antennas with the multilayered structure is analysed by using the moment method technique in the spectral domain. The analysis is carried out for two different feeding structures : directfeeding structure and electromagnetic-feeding structure. In order to obtain the accurate input impedance, the current distribution on the microstrip feed line is modeled by the quasi-TEM travelling wave and the PWS(piecewise sinusoidal) mode. The input impedances of the designed microstrip antennas are measured and compared with the calculation. which shows a good agreement.