• 천문학회보
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• 제39권2호
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• pp.97.2-97.2
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• 2014

In this paper, we study the stability and dynamics of a magnetic field producing the M6.6 class solar flare taking place in NOAA active region (AR) 11158 on 2011 February 13th. Toriumi et. al. (2013) recently suggest that a fine scale magnetic structure on the photosphere gives a major possibility to produce the M6.6 class flare. On the other hand, they don't discuss the torus instability as a plausible mechanism even though Zhao et. al. (2014) and Janvier et. al. (2014) suspect it as the trigger mechanism of X2.2 class flare taking place later in the same AR. We are the first to investigate the stability of a nonlinear force-free field (NLFFF) prior to the M6.6 class flare against the torus instability by using analytical and numerical approaches. Consequently, we found that our NLFFF is quite stable against small perturbation. This result supports that the flare is triggered by the photospheric motion suggested by Toriumi et. al. (2013). We further perform another MHD simulation with an anomalous resistivity using the NLFFF as an initial condition. As a result, we found the eruption of strongly twisted lines. We compare our simulation results with observations and discuss relevant dynamics in detail.

• 한국통신학회논문지
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• 제26권12A호
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• pp.1990-1999
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• 2001

본 논문에서는 단소자 적외선 레티클 탐색기의 단점을 해결하기 위해 적외선의 두 대역을 이용하는 2-color 회전 동심원 레티클 탐색기(concentric annular ring reticle seeker)의 시뮬레이션 툴이 제안된다. 표적 및 섬광탄(flare)의 모델링과 비례항법 유도(proportional navigation guidance) 루프를 포함한 동적인 시뮬레이션 툴 상에서 동심원 레티클 탐색기의 추적 성능과 섬광탄에 의한 영항 등을 분석한다. 또한 다양한 상량에서 운용되는 섬광탄의 영향을 효과적으로 배제하기 위해 LMS 방법을 이용한 새로운 반대응능력(counter-countermeasure)이 제안된다. SWIR 및 MWIR 대역에서 표적과 섬광탄의 상대적 분포특성을 이용함으로써 섬광탄에 효과적으로 대처할 수 있으며, 교전 시나리오에서 기존 반대응 기법과의 비교를 통해 제안된 알고리즘의 향상된 추적 성능을 확인하였다.

• 패션비즈니스
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• 제1권4호
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• pp.49-54
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• 1997

Methods of the flare skirt pattern making are presented variously among foreign and domestic test books. Three of them are : First the method is using the basic skirt pattern, secondly the method is quartering rectangle of skirt length $\times\frac{W}4$, finally the method is substituting waist size for formula. But, these books don't include the calculating method of the hem circumference. This calculating method express the shape of flare skirt and the using length of trimming -race and frill-. This study aims at proposing the calculating formula of the hem circumference and the standardization of pattern making technical skill. The result were as follows. 1. The calculating formula of hem circumference had regular ratio in $180^{\circ}$, $270^{\circ}$ and $360^{\circ}C$ flare. That was (HEM) = $(\frac{(5\;{\times}\;(W\;+\;1)}{4\;{\times}\;A}+(SK.L))\;{\times}\;A\;{\times}\;0.785$. A was 4 in $180^{\circ}$, 6 in $270^{\circ}$, 8 in $360^{\circ}$. 2. The error of hem circumference from 46 to 86 centimeter of waist size was between 0.11875 and -0.63125 centimeter in $180^{\circ}$, $270^{\circ}$ and $360^{\circ}$ flare skirt. This formula was less in the error.

• 대한조선학회논문집
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• 제44권3호
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• pp.279-284
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• 2007

As a container vessel becomes larger, the bow flare becomes larger. The large bow flare structures are often subjected to dynamic pressure loads due to bow flare slamming occurring in rough seas. The aim of this paper is to investigate the characteristics of bow flare slamming pressure measured in a real voyage through the North Pacific Ocean. The characteristics of impact pressure load caused by slamming is addressed in terms of the pressure pulse-time history which involves rising time, peak pressure, decaying time and type of pressure decay. The values were presented using non-dimensional parameters.

• 천문학회보
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• 제36권1호
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• pp.29.2-29.2
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• 2011

Although stellar flares have a long history of observations, there are few concrete understanding about underlying physical processes and meaningful correlations with other stellar properties. Most of previous observations dealt with only a small number of sample stars, and therefore not sufficient to support generalized statistical studies. Based on one-month long MMT time-series observations of the open cluster M37, we monitored light variations of nearly 2,500 M-dwarf stars and successfully identified 606 flare events from 422 stars. This is a rare attempt to estimate true flare rates and properties among many stars of the same age and mass group. For each flare, we considered both observational and physical parameters including flare shape, duration before and after the peak, baseline magnitude before and after the peak, peak magnitudes, total energy and peak energy, etc. We find significant correlations between some of key parameters over a wide range of energy ($Er=10^{32}{\sim}10^{36}ergs$). For instance, regardless of stellar luminosities, the energy power spectrum of flares can be approximated by a power law (${\beta}=0.83-0.97$). This suggests that flares follow similar physical mechanisms for atmospheric heating and cooling among these low-mass stars. From this MMT data set, we derived an average flaring rate of $0.019 hr^{-1}$ among flare stars and $0.003 hr^{-1}$ for all M-dwarf candidates. We will report the details of our analysis and discuss physical implications.

• 대한조선학회논문집
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• 제40권3호
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• pp.22-28
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• 2003

In rough seas, bow-flare regions of the full ships (tanker and bulk carrier) are subiect to high impact pressures due to the on-coming breaking waves. And many ships suffer structural damages in that region, even though they were built under the bow structure strengthening rules of the ship classes. So, a new design method for bow-flare structure is highly required. In this paper, a new prediction method of the bow-flare impact pressure (in terms of equivalent static pressure) acting on the full ships' bow is presented. This method is based on the 6 full ships' damage analysis and the breaking wave impact mechanism. Calculation results of the bow-flare impact pressure and the shell plate thickness are shown and discussed. Through the example calculations, it was found that the present method is useful for the structure design of the full ships' bow.

• 대한교통학회지
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• 제28권6호
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• pp.25-32
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• 2010

이 연구는 회전교차로의 진입 및 진출차로 퍼짐을 다루고 있다. 연구의 목적은 회전교차로의 진입 및 진출차로 퍼짐에 따른 회전교차로의 진체 및 용량효과를 분석하는데 있다. 이를 위해 회전교차로 및 진출입차로 퍼짐에 따른 교통량별로 시나리오를 작성하고 VISSIM을 이용하여 분석하였다. 분석된 주요 결과는 다음과 같다. 첫째, 1차로 및 2차로 회전교차로의 차량당 평균제어지체를 분석한 결과, 1차로 회전교차로는 총 진입교통량이 2,400pcph에서, 2차로 회전교차로는 4,400pcph에서 서비스수준 F에 도달하는 것으로 분석되었다. 둘째, 진입차로 퍼짐 회전교차로에서 총 진입교통량 2,800~3,200pcph가 서비스수준 F인 것으로 분석되어, 1차로 회전교차로 보다 400~800pcph정도의 용량 증대가 있는 것으로 분석되었고, 진입 및 진출차로 퍼짐 회전교차로에서 총 진입 교통량 3,200~3,600pcph가 서비스수준 F인 것으로 분석되어, 1차로 회전교차로보다 800~1,200pcph정도의 용량 증대가 있는 것으로 분석되었다. 마지막으로, 회전교차로와 퍼짐 회전교차로의 비교분석 결과, 퍼짐 회전교차로의 용량은 1차로 회전교차로와 2차로 회전교차로의 중간 수준이므로 회전교차로의 유형에 추가할 수 있을 것으로 판단된다.

• 천문학회보
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• 제42권2호
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• pp.59.5-60
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• 2017

We present the relationship between vector magnetic field parameters and solar major flare occurrence rate. Based on this, we are developing a forecast model of major flare (M and X-class) occurrence rate within a day using hourly vector magnetic field data of Space-weather HMI Active Region Patch (SHARP) from May 2010 to April 2017. In order to reduce the projection effect, we use SHARP data whose longitudes are within ${\pm}60$ degrees. We consider six SHARP magnetic parameters (the total unsigned current helicity, the total photospheric magnetic free energy density, the total unsigned vertical current, the absolute value of the net current helicity, the sum of the net current emanating from each polarity, and the total unsigned magnetic flux) with high F-scores as useful predictors of flaring activity from Bobra and Couvidat (2015). We have considered two cases. In case 1, we have divided the data into two sets separated in chronological order. 75% of the data before a given day are used for setting up a flare model and 25% of the data after that day are used for test. In case 2, the data are divided into two sets every year in order to reduce the solar cycle (SC) phase effect. All magnetic parameters are divided into 100 groups to estimate the corresponding flare occurrence rates. The flare identification is determined by using LMSAL flare locations, giving more numbers of flares than the NGDC flare list. Major results are as follows. First, major flare occurrence rates are well correlated with six magnetic parameters. Second, the occurrence rate ranges from 0.001 to 1 for M and X-class flares. Third, the logarithmic values of flaring rates are well approximated by two linear equations with different slopes: steeper one at lower values and lower one at higher values. Fourth, the sum of the net current emanating from each polarity gives the minimum RMS error between observed flare rates and predicted ones. Fifth, the RMS error for case 2, which is taken to reduce SC phase effect, are smaller than those for case 1.

• 천문학회보
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• 제46권1호
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• pp.42.1-42.1
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• 2021

In this study, we present a visual explanation of a deep learning solar flare forecast model and its relationship to physical parameters of solar active regions (ARs). For this, we use full-disk magnetograms at 00:00 UT from the Solar and Heliospheric Observatory/Michelson Doppler Imager and the Solar Dynamics Observatory/Helioseismic and Magnetic Imager, physical parameters from the Space-weather HMI Active Region Patch (SHARP), and Geostationary Operational Environmental Satellite X-ray flare data. Our deep learning flare forecast model based on the Convolutional Neural Network (CNN) predicts "Yes" or "No" for the daily occurrence of C-, M-, and X-class flares. We interpret the model using two CNN attribution methods (guided backpropagation and Gradient-weighted Class Activation Mapping [Grad-CAM]) that provide quantitative information on explaining the model. We find that our deep learning flare forecasting model is intimately related to AR physical properties that have also been distinguished in previous studies as holding significant predictive ability. Major results of this study are as follows. First, we successfully apply our deep learning models to the forecast of daily solar flare occurrence with TSS = 0.65, without any preprocessing to extract features from data. Second, using the attribution methods, we find that the polarity inversion line is an important feature for the deep learning flare forecasting model. Third, the ARs with high Grad-CAM values produce more flares than those with low Grad-CAM values. Fourth, nine SHARP parameters such as total unsigned vertical current, total unsigned current helicity, total unsigned flux, and total photospheric magnetic free energy density are well correlated with Grad-CAM values.

• 복식문화연구
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• 제17권3호
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• pp.472-483
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• 2009

The purpose of this study is to analyse the effects of knit samples' mechanical properties on changes of skirt length of knit flared skirt, and to compare it to the knitting method of a seamless knitted flare skirt. So, I compared the appearance and 3-dimensional shape of a seamless knitted flare skirt with those of a fully cut knit flared skirt. For this study, 18 kinds of cut and sew or seamless knitted test garment were made. The data analysis methods used in this study were descriptive statistics, one-way ANOVA, correlation analysis, and regression analysis. The results are as follows: The result of the evaluation of knit samples' mechanical properties by the KES-FB system showed that elongation decreased as gauge increased and course direction was greatest among grain directions. The length change after wearing the knitted flare skirts appeared wholly equal to the seamless knitted, compared with the cut and sew. The change was biggest at $180^{\circ}$, 7G of the cut and sew. In grain direction, bias cut showed more than 1.2cm of length change. As the weight and thickness increased, the length changes become larger. The regression analysis indicated that the greatest contributive variables on the length changes were elongation, weight, and thickness.