• Title/Summary/Keyword: 비선형 계수 추정

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Gender Difference in Self-Employment Rates In Korea (남녀간 자영업 비중의 격차 분석)

  • Kim, Woo-Yung
    • Journal of Labour Economics
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    • v.24 no.2
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    • pp.1-34
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    • 2001
  • This study analyzes the male-female difference in self-employment rates in Korea using panel data constructed from the Economically Active Population Survey in 1999. Given that most studies on self-employment have focused on male self-employment and have not examined why self-employment rate is usually higher among males than females, this study certainly extends the existing literature on this subject This study consists of two parts. The first part deals with estimating self-employment rates for males and female within a Markov framework. The second part presents decomposition results of the male-female differential in self-employment rates. Major findings of the study are (1) self-employment rate is higher for males than females because entry into self-employment is larger but exit from self-employment is smaller for males than female, (2) higher entry probability for males is due to differences in coefficients of transition probability functions while lower exit probability for males is due to differences in characteristics, (3) a large part of male-female gap in self-employment rates results from differences in being a head of family, marital status and age between males and females.

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Strength and Deformation Characteristics on Stabilized Pavement Geomaterials (II) : Numerical Analysis (안정처리된 도로하부 지반재료의 강도 및 변형특성 (II) : 수치해석)

  • Park, Seong-Wan;Ji, Jong-Keun
    • International Journal of Highway Engineering
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    • v.11 no.2
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    • pp.205-216
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    • 2009
  • As a subsequent study, this paper presents a comparative evaluation of structural responses in asphalt pavements with stabilized foundations. The approach based on a finite element analysis which incorporates non-linear behaviors of pavement geomaterials is used to estimate each performance indicator under standard single axle loading condition. In addition, results from laboratory tests are used to provide physical and mechanical properties of stabilized geomaterials for analyzing various pavement structures. Changes in pavement responses with varying layer thickness and stabilizer contents were investigated. It is found that the effect of layer thickness and stabilizer content is a critical factor in structural response of stabilized pavements. Moreover, a design criterion is proposed for selecting minimum contents of stabilizer of coarse-grained geomaterials based on a result of unconfined compressive strength and proper layer thickness of foundations.

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A Study on Calculating Inductance Characteristics of Switched Reluctance Motor (스위치드 리럭턴스 전동기의 인덕터스 산정에 관한 연구)

  • 최경호;김동희;노채균;김민희
    • The Transactions of the Korean Institute of Power Electronics
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    • v.6 no.4
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    • pp.333-340
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    • 2001
  • This paper presents a calculating method for inductance of the Switched Reluctance Motor(SRM) for torque characteristics and driving by analytical model. The torque generating characteristics of the SRM depend on the phase current and the inductance variation features, but Its nonlinear magnetic characteristics make it difficult to calculating inductance. Recently, The approaches for calculating inductance have taken vary from detailed finite element method(FEM) and Fitting method in magnetization curves using complex nonlinear magnetic circuit models. But those methods have not satisfactory approach for machine performance calculations, because of having a long time and remodeling for analyses, therefore thus an alternative approach is required. So it is suggested simply calculating method of the inductance based on designed data of machinery by analytical model in unaligned and aligned rotor. In order to prove the calculating, there are compare with analytical FEM. direct measurement, this method, and simulation. The compared result is shown to obtain good accuracy.

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Estimation of Suspended Sediment Concentration in Small Stream with Acoustic Backscatter from Horizontal ADCP based on Real-Scale Field Experiment (실규모 현장 실험 기반 H-ADCP 초음파 산란도 활용 소하천용 하천 부유사 농도 측정 기법 개발)

  • Seo, Kanghyeon;Kim, Dongsu;Son, Geunsoo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.36 no.6
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    • pp.1023-1035
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    • 2016
  • Suspended sediment concentration (SSC) is a crucial riverine parameter in terms that it can be utilized for analyzing sediment transport, stability assessment of river and structure and so on. However, in case of domestic, sediment discharge data are not enough because of using conventional sediment samplers. This study aimed at developing a practical technique for estimating suspended sediment concentration in high spatial and temporal resolution by building relationship between acoustic backscatter (or SNR) from H-ADCP with actually observed data using LISST-100X. In this regard, a dedicated correction algorithm was proposed particularly for the adapted H-ADCP (SonTek SL-3000). Then, a SNR-SSC relation was built based upon a real-scale field experiment, where both H-ADCP and LISST-100X were concurrently operated to observe SNR and SSC, respectively. The coefficient of determination for the developed regression equation of SNR-SSC relation was around 0.85~0.88, thereby the relation could be evaluated to be highly correlated. The result of this study might be potentially applied for real-time and simultaneous observation of SSC when H-ADCP could be applied.

The Variation Characteristics of Groundwater Level with Distance from Shoreline in the Jeju Island (제주도 지역의 해안선에서 이격거리에 따른 지하수위 변동특성)

  • Kang, Dong-Hwan;Yang, Sung-Il;Kim, Tae-Yeong;Park, Hyun-Joo;Kwon, Byung-Hyuk
    • The Journal of Engineering Geology
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    • v.18 no.2
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    • pp.167-176
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    • 2008
  • The variation characteristics of groundwater level with distance from shoreline at Jeju Island was investigated using groundwater level data monitored from 257 wells for dry season (December 1998) and wet season (July 1997), respectively. Groundwater levels of the dry season were $7.46{\sim}203.8\;m$ with an average of 60.49 m, while those of the wet season were $4.01{\sim}204.10\;m$ with an average of 57.66 m. Groundwater level of the dry season was higher than that of the wet season, which was caused by heavy rains between June and October, 1998 at the Jeju Island. Correlation coefficients between altitude and groundwater level for dry and wet seasons were above 0.86, and those between dry season and wet season groundwater levels were very high above 0.95. 257 groundwater level data were classified at an interval of 500 m. Average values for altitude, groundwater levels and distance from shoreline were calculated for 17 intervals. Altitude and groundwater level fur dry and wet seasons at $0{\sim}4\;km$ intervals were increased with distance from shoreline, but those at $4{\sim}9\;km$ intervals were irregularity. Linear functions of the groundwater level for dry and wet seasons as distance from shoreline were estimated, and the coefficient of determinant at $0{\sim}4\;km$ interval data was higher than it at $0{\sim}9\;km$ interval data. Increasing rate of groundwater level at $0{\sim}4\;km$ intervals was more 2 times than it at $0{\sim}9\;km$ intervals. This results are caused by linear increase of groundwater level to 4 km from shoreline and by irregularity of groundwater level at the $4{\sim}9\;km$ intervals.

Flood Risk Estimation Using Regional Regression Analysis (지역회귀분석을 이용한 홍수피해위험도 산정)

  • Jang, Ock-Jae;Kim, Young-Oh
    • Journal of the Korean Society of Hazard Mitigation
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    • v.9 no.4
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    • pp.71-80
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    • 2009
  • Although desire for living without hazardous damages grows these days, threats from natural disasters which we are currently exposed to are quiet different from what we have experienced. To cope with this changing situation, it is necessary to assess the characteristics of the natural disasters. Therefore, the main purpose of this research is to suggest a methodology to estimate the potential property loss and assess the flood risk using a regional regression analysis. Since the flood damage mainly consists of loss of lives and property damages, it is reasonable to express the results of a flood risk assessment with the loss of lives and the property damages that are vulnerable to flood. The regional regression analysis has been commonly used to find relationships between regional characteristics of a watershed and parameters of rainfall-runoff models or probability distribution models. In our research, however, this model is applied to estimate the potential flood damage as follows; 1) a nonlinear model between the flood damage and the hourly rainfall is found in gauged regions which have sufficient damage and rainfall data, and 2) a regression model is developed from the relationship between the coefficients of the nonlinear models and socio-economic indicators in the gauged regions. This method enables us to quantitatively analyze the impact of the regional indicators on the flood damage and to estimate the damage through the application of the regional regression model to ungauged regions which do not have sufficient data. Moreover the flood risk map is developed by Flood Vulnerability Index (FVI) which is equal to the ratio of the estimated flood damage to the total regional property. Comparing the results of this research with Potential Flood Damage (PFD) reported in the Long-term Korea National Water Resources Plan, the exports' mistaken opinions could affect the weighting procedure of PFD, but the proposed approach based on the regional regression would overcome the drawback of PFD. It was found that FVI is highly correlated with the past damage, while PFD does not reflect the regional vulnerabilities.

A study on the Derivation of GIUH-Clark Model (GIUH-Clark 모형의 유도에 관한 연구)

  • Lee, Byung Woon;Jang, Dae Won;Kim, Hung Soo;Seoh, Byung Ha
    • Proceedings of the Korea Water Resources Association Conference
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    • 2004.05b
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    • pp.731-736
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    • 2004
  • 강우-유출과정의 수문학적 현상을 보다 정확히 분석하고 예측하는 기법으로 강우에 의한 유출의 반응을 나타내는 지체시간, 도달시간 등 수문학적 반응시간을 유역의 지형형태학적 인자들과 연계하는 방법이 많이 이용되고 있다. 이에 본 연구에서는 Clark방법과 지형형태학적 순간단위도(GIUH)를 이용하여 계측유역의 강우-유출반응을 모의하였고, 이를 관측된 값과 비교하여 미계측유역의 적용성 여부를 검토해보았다. 대상 유역의 하상지형인자 및 지형형태학적 특성은 Arc-View를 이용하여 구하였으며, 이를 기존의 문헌자료와 비교해보았다. Clark방법의 매개변수의 결정에 있어서 시간-면적곡선은 HEC-1의 무차원 식을 이용하였고, 도달시간은 Kirpich 공식을 이용하여 구하였으며, 저류상수는 Clark방법에 의해 추정된 순간단위도의 첨두유량이 Horton의 차수비의 함수로 구한 철두유량과 같아지는 값으로 결정하였다. 본 연구는 전적비교를 출구점으로하는 유역면적 $8.5km^2$인 설마천을 대상유역으로 하였으며, 모의된 강우-유출반응과 비교하기 위해 사용된 강우사상은 2002년의 8월 4일과 2002년 10월 6일의 10분 단위 우량이다. Clark방법과 GIUH를 이용하여 모의한 유출곡선과 관측된 유출곡선을 비교해본 결과 첨두유량은 8월의 강우사상 때는 $21\%$크게, 10월의 강우사상 때는 $35\%$작게 나타났다. 첨두시간은 모의된 경우가 각각 10분, 20분 빨리 도달하였다. 또한 이러한 결과는 유역의 도달시긴에 가장 민감하게 반응함을 알 수 있었다. 따라서, 유역의 도달시간 산정에 주의를 요한다면 프랙탈 차원이 유사한 미계측유역의 수문곡선 산정에 있어서 Clark방법과 GIUH를 이용하는 방법도 유용하다고 사료된다. 주는 각 수문인자 중 강우시간분포와 유효우량 산정방법 그리고 유출모형에 대해 자자 검토하였으며, 최종적으로 면적에 따른 임계지속기간과 유출량의 변화를 검토해 보았다.이를 각각의 경우의 해석해 결과와 비교${\cdot}$분석하였다. 후방추적 퍼프모형은 전방추적 퍼프모형에 비하여 사용된 퍼프수와 관계없이 작은 오차를 발생하였으며, 전체적으로 퍼프 모형이 입자모형보다는 훨씬 적은 수의 계산을 통해서도 작은 오차를 나타낼 수 있다는 것을 알 수 있었다. 그러나 Gaussian 분포를 갖는 퍼프모형은 전단흐름에서의 긴 유선형 농도분포를 모의할 수 없었고, 이에 관한 오차는 전단계수가 증가함에 따라 비선형적으로 증가하였다. 향후, 보다 다양한 흐름영역에서 장${\cdot}$단점 분석 및 오차해석을 수행한 후에 각각의 Lagrangian 모형의 장점만을 갖는 모형결합 방법을 제시할 수 있을 것으로 판단된다.mm/$m^{2}$로 감소한 소견을 보였다. 승모판 성형술은 전 승모판엽 탈출증이 있는 두 환아에서 동시에 시행하였다. 수술 후 1년 내 시행한 심초음파에서 모든 환아에서 단지 경등도 이하의 승모판 폐쇄 부전 소견을 보였다. 수술 후 조기 사망은 없었으며, 합병증으로는 유미흉이 한 명에서 있었다. 술 후 10개월째 허혈성 확장성 심근증이 호전되지 않아 Dor 술식을 시행한 후 사망한 예를 제외한 나머지 6명은 특이 증상 없이 정상 생활 중이다 결론: 좌관상동맥 페동맥이상 기시증은 드물기는 하나, 영유아기에 심근경색 및 허혈성 심근증 또는 선천성 승모판 폐쇄 부전등을 초래하는 심각한 선천성 심질환이다. 그러나 진단 즉시 직접 좌관상동맥-대동맥 이식술로 수술적 교정을 해줌으로써 좋은 성적을 기대할 수 있음을 보여주었다.특히 교사들이 중요하

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Development of Stochastic Decision Model for Estimation of Optimal In-depth Inspection Period of Harbor Structures (항만 구조물의 최적 정밀점검 시기 추정을 위한 추계학적 결정모형의 개발)

  • Lee, Cheol-Eung
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.28 no.2
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    • pp.63-72
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    • 2016
  • An expected-discounted cost model based on RRP(Renewal Reward Process), referred to as a stochastic decision model, has been developed to estimate the optimal period of in-depth inspection which is one of critical issues in the life-cycle maintenance management of harbor structures such as rubble-mound breakwaters. A mathematical model, which is a function of the probability distribution of the service-life, has been formulated by simultaneously adopting PIM(Periodic Inspection and Maintenance) and CBIM(Condition-Based Inspection and Maintenance) policies so as to resolve limitations of other models, also all the costs in the model associated with monitoring and repair have been discounted with time. From both an analytical solution derived in this paper under the condition in which a failure rate function is a constant and the sensitivity analyses for the variety of different distribution functions and conditions, it has been confirmed that the present solution is more versatile than the existing solution suggested in a very simplified setting. Additionally, even in that case which the probability distribution of the service-life is estimated through the stochastic process, the present model is of course also well suited to interpret the nonlinearity of deterioration process. In particular, a MCS(Monte-Carlo Simulation)-based sample path method has been used to evaluate the parameters of a damage intensity function in stochastic process. Finally, the present stochastic decision model can satisfactorily be applied to armor units of rubble mound breakwaters. The optimal periods of in-depth inspection of rubble-mound breakwaters can be determined by minimizing the expected total cost rate with respect to the behavioral feature of damage process, the level of serviceability limit, and the consequence of that structure.

A selective sparse coding based fast super-resolution method for a side-scan sonar image (선택적 sparse coding 기반 측면주사 소나 영상의 고속 초해상도 복원 알고리즘)

  • Park, Jaihyun;Yang, Cheoljong;Ku, Bonwha;Lee, Seungho;Kim, Seongil;Ko, Hanseok
    • The Journal of the Acoustical Society of Korea
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    • v.37 no.1
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    • pp.12-20
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    • 2018
  • Efforts have been made to reconstruct low-resolution underwater images to high-resolution ones by using the image SR (Super-Resolution) method, all to improve efficiency when acquiring side-scan sonar images. As side-scan sonar images are similar with the optical images with respect to exploiting 2-dimensional signals, conventional image restoration methods for optical images can be considered as a solution. One of the most typical super-resolution methods for optical image is a sparse coding and there are studies for verifying applicability of sparse coding method for underwater images by analyzing sparsity of underwater images. Sparse coding is a method that obtains recovered signal from input signal by linear combination of dictionary and sparse coefficients. However, it requires huge computational load to accurately estimate sparse coefficients. In this study, a sparse coding based underwater image super-resolution method is applied while a selective reconstruction method for object region is suggested to reduce the processing time. For this method, this paper proposes an edge detection and object and non object region classification method for underwater images and combine it with sparse coding based image super-resolution method. Effectiveness of the proposed method is verified by reducing the processing time for image reconstruction over 32 % while preserving same level of PSNR (Peak Signal-to-Noise Ratio) compared with conventional method.

Influence of Menstrual Cycle on Inflammatory Markers in Gingival Crevicular Fluid : Pilot Study (월경주기에 따른 치은열구액 내 염증지표의 변화: 예비 연구)

  • Park, Hoo-Seob;Hwang, Soo-Jeong;Cho, Min-Jeong;Kim, Do-Kyoung;Yang, Seon-Youn
    • Journal of dental hygiene science
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    • v.12 no.1
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    • pp.71-77
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    • 2012
  • Sex Hormones exert significant influence in body physiology throughout life. Some reports suggested increased sex hormone levels correlate with an increased prevalence of gingivitis. The objectives of this pilot study are to(1) address the link between menstrual cycle and MMP-9, MMP-8, IL-$1{\beta}$ of gingival crevicular fluid during 4 weeks and (2) discuss the major biomarker of periodontal status. 7 female and 3 male volunteer who didn't have smoking habit, medical and dental disease after informed consent, were seen twice a week for 4 weeks. GCF samples were collected and GCF levels of MMP-9, MMP-8, IL-$1{\beta}$ were measured by enzyme-linked immunosorbent assay. The GCF levels of MMP-9, MMP-8, IL-$1{\beta}$ had fluctuation according to menstrual cycle, but the changes of those were not significant by Friedman matched samples test. There is no difference between female and male subjects by Mann-Whitney U test. The correlation of MMP-8, MMP-9 and IL-$1{\beta}$ showed strong by Spearman correlation(0.644-0.945). This study confirms menstrual cycle doesn't influence the periodontium of healthy female subjects.