• Communications for Statistical Applications and Methods
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• 제4권1호
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• pp.229-241
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• 1997

We consider discrimination curve and minimum dwell time for Poisson distribution and Poisson-power function distribution. Let the random variable X has Poisson distribution with mean .lambda.. For the hypothesis testing H$\_$0/:.lambda. = t vs. H$\_$1/:.lambda. = d (d$\_$0/ if X.leq.c. Since a critical value c can not be determined to satisfy both types of errors .alpha. and .beta., we considered discrimination curve that gives the maximum d such that it can be discriminated from t for a given .alpha. and .beta.. We also considered an algorithm to compute the minimum dwell time which is needed to discriminate at the given .alpha. and .beta. for the Poisson counts and proved its convergence property. For the Poisson-power function distribution, we reject H$\_$0/ if X.leq..'{c}.. Since a critical value .'{c}. can not be determined to satisfy both .alpha. and .beta., similar to the Poisson case we considered discrimination curve and computation algorithm to find the minimum dwell time for the Poisson-power function distribution. We prosent this algorithm and an example of computation. It is found that the minimum dwell time algorithm fails for the Poisson-power function distribution if the aiming error variance .sigma.$\^$2/$\_$2/ is too large relative to the variance .sigma.$\^$2/$\_$1/ of the Gaussian distribution of intensity. In other words, if .ell. is too small, we can not find the minimum dwell time for a given .alpha. and .beta..

• 천문학회보
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• 제43권1호
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• pp.56.1-56.1
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• 2018

Tidal disruption events (TDEs) provide evidence for quiescent supermassive black holes (SMBHs) in the centers of inactive galaxies. TDEs occur when a star on a parabolic orbit approaches close enough to a SMBH to be disrupted by the tidal force of the SMBH. The subsequent super-Eddington accretion of stellar debris falling back to the SMBH produces a characteristic flare lasting several months. The theoretically expected bolometric light curve decays with time as proportional to $t^{-5/3}$. However, the light curves observed in most of the optical-UV TDEs deviate from the $t^{-5/3}$ decay rate especially at early time, while the light curves of some soft-X-ray TDEs are overall in good agreement with the $t^{-5/3}$ law. Therefore, it is required to construct the theoretical model for explaining these light curve variations consistently. In this paper, we revisit the mass fallback rates analytically and semi-analytically by taking account of the structure of the star, which is simply modeled by the polytrope. We find the relation between a polytropic index and the power law index of the mass fallback rate. We also discuss whether and how the decay curves, which we derived, fit the observed ones.

• 전기학회논문지P
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• 제62권4호
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• pp.223-226
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• 2013

In this study, we investigated the electro-optical(EO) characteristic of fringe-field switching(FFS) mode cell by the two kinds of ultraviolet(UV) alignment method on the organic thin film(polyimide: PI). The suitable organic layersfor FFS cell and the aligning capabilities of nematic liquid crystal(NLC) using the in-situ photoalignment method were studied Disclination is observed after conventional photoalignment method for 1h, and in-situ photoalignment method for 1h. Monodomain alignment of the NLC can be observed via in-situ photoalignment method for 2h and 3h. It is considered that NLC alignment is due to photo-depolymerization of the polymer with oblique non-polarized UV irradiation on PI surface. An unstable V-T curve of UV-aligned FFS-LCD with conventional photoalignment method can be achieved. However, a stable V-T curve of UV-aligned FFS-LCD with in-situ photoalignment method(1h), and V-T curve of UV-aligned FFS-LCD with in-situphotoalignment method was much stable comparing with that of other UV-aligned FFS-LCD's. As a result, more stable EO performanceof UV-aligned FFS-LCD with in-situphotoalignment method for 3h is obtained than that of the other UV-aligned FFS-LCD's.

• 대한수학회보
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• 제61권2호
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• pp.401-419
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• 2024

Let K, H, K_II and H_II be the Gaussian curvature, the mean curvature, the second Gaussian curvature and the second mean curvature of a timelike tubular surface T_γ(α) with the radius γ along a timelike curve α(s) in Minkowski 3-space E³₁. We prove that T_γ(α) must be a (K, H)-Weingarten surface and a (K, H)-linear Weingarten surface. We also show that T_γ(α) is (X, Y)-Weingarten type if and only if its central curve is a circle or a helix, where (X, Y) ∈ {(K, K_II), (K, H_II), (H, K_II), (H, H_II), (K_II , H_II)}. Furthermore, we prove that there exist no timelike tubular surfaces of (X, Y)-linear Weingarten type, (X, Y, Z)-linear Weingarten type and (K, H, K_II, H_II)-linear Weingarten type along a timelike curve in E³₁, where (X, Y, Z) ∈ {(K, H, K_II), (K, H, H_II), (K, K_II, H_II), (H, K_II, H_II)}.

• 벤처창업연구
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• 제10권3호
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• pp.123-131
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• 2015

빠르게 발전하는 IoT 시대에 발맞추어, IoT 적용과 관련하여 다양한 시나리오에 이용할 수 있는 경영 전략을 이끌어내기 위한 체계적인 접근이 요구된다. 본 논문에서는, IOT를 적용할 때 시장 잠재력을 평가하고 초기 경영 전략을 세울 때 사용할 수 있는 개념적 틀을 제시한다. 개념적 틀은 널리 알려진 가치곡선분석, 생태계 분석 그리고 품질의 집을 이용하여 구성하였다. 가치곡선 분석은 소비자에게 가치를 주는 항목을 파악하는 부분과 이와 관계된 공급자의 강점을 분석하는데 이용된다. 생태계 분석은 공급사슬 상의 참가자들과 그들의 관계를 파악하는데 이용된다. 품질의 집은 공급자에게 소비자의 요구사항을 파악하고 그것을 공급자의 기술적인 요구 조건과 비교하여 초기 사업 전략을 구축하는데 적합한 분석도구이다. 본 논문에서는 우리가 제시한 개념적 틀을 IoT를 적용하였을 때 큰 발전 가능성이 있는 Car-sharing 서비스와 telehealth 서비스 이렇게 두 가지 서비스에 적용하여 분석하였다.

• 한국산학기술학회논문지
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• 제11권9호
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• pp.3155-3160
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• 2010

최근 자동차 산업은 고효율 자동차의 개발에 박차를 가하고 있으며 이에 따라 차체 경량화 및 내식성 방지를 위한 고강도강 및 도금강의 사용이 증가하고 있다. 이에 따라 본 연구에서는 자동차 차체에 쓰이는 3종의 다른 강판에 대하여, 겹침 순서에 따른 용접 특성을 시뮬레이션 기법을 이용하여 분석하였다. 자동차 차체에 많이 사용되는 EDDQ 급의 도금강판 0.7t와 인장강도 440 MPa급의 440R 1.2t, 그리고 AHSS (Advanced High Strength Steel)인 DP 590 0.2t 판재에 대하여 겹치기 순서에 따른 용접 특성을 시뮬레이션 하였고, 너겟 성장 곡선 및 전류에 따른 너겟의 크기로 그 용접성을 분석하였다. 또한 용접 시 발생되는 각 접촉부의 접촉저항을 이용하여 겹침순서에 따른 너겟의 크기를 분석하였으며, 이를 통해 최적의 겹치기 순서를 제안할 수 있었다.

• Journal of Chest Surgery
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• 제50권4호
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• pp.275-280
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• 2017

Background: Video-assisted thoracoscopic surgery (VATS) anatomic lung resections are gradually becoming the standard surgical approach in early-stage non-small cell lung cancer (NSCLC). The technique is being applied in cases of larger tumors depending on the experience of the surgical team. The objective of this study was to compare early surgical and survival outcomes in patients undergoing anatomic pulmonary resections using VATS and thoracotomy techniques for clinical T2 NSCLC during the adaptation period of the surgical team to the VATS approach. Methods: The data of all patients who underwent anatomic pulmonary resection for NSCLC using VATS and open techniques since April 2012 were recorded to create a prospective lung cancer database. Clinical T2 NSCLC patients who underwent VATS anatomic lung resection were identified and compared with cT2 patients who underwent open resection. Results: Between April 2012 and August 2014, 269 anatomical resections for NSCLC were performed (80 VATS and 189 thoracotomy). Thirty-four VATS patients who had clinical T2 disease were identified and stage-matched to thoracotomy patients. The average tumor diameter was comparable ($34.2{\pm}11.1{\times}29.8{\pm}10.1mm$ vs. $32.3{\pm}9.8{\times}32.5{\pm}12.2mm$, p=0.4). Major complications were higher in the thoracotomy group (n=0 vs. n=5, p=0.053). There was no 30-day mortality, and the 2-year survival rate was 91% for VATS and 82% for thoracotomy patients (p=0.4). Conclusion: VATS anatomic resections in clinical T2 NSCLC tumors are safe and have perioperative and pathologic outcomes similar to those of thoracotomy, while remaining within the learning curve.

• 한국주조공학회지
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• 제33권1호
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• pp.13-21
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• 2013

The effects of rare earth element (R.E.) and cooling rate on the eutectic reaction of flake graphite cast irons were studied by combined analysis of macro/micro-structure and cooling curve data. The correlation between eutectic reaction parameter and macro/micro-structure was systematically investigated. Two sets of chemical compositions with the different addition of R.E. were designed to cast. Three types of molds for cylindrical specimens with the different diameters were prepared to analyze cooling rate effect. The difference between undercooling temperature and cementite eutectic temperature (${\Delta}T_1=T_{U}-T_{E,C}$), which is increased by adding R.E. and decreased by increasing cooling rate, is considered to be a suitable eutectic reaction parameter for predicting graphite morphology. According to the criterion, A-type graphite is mainly suggested to form for ${\Delta}T_1$ over $20^{\circ}C$. Eutectic reaction time (${\Delta}t$), which is decreased by adding R.E. or increasing cooling rate, is a suitable eutectic reaction parameter for predicting eutectic cell size. Eutectic cell size is found to decrease in a proportion to the decrease of ${\Delta}t$.

• 대한수학회논문집
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• 제24권2호
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• pp.181-185
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• 2009

The Drinfeld modular function ${\mu}$ is a generator of the function field of the Drinfeld modular curve $X_0(T)$ and has an t-expansion with the integral coefficients at infinity. In this paper, we show that the coefficients of ${\mu}$ has congruence properties modulo powers of T.

• 한국컴퓨터그래픽스학회논문지
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• 제6권1호
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• pp.37-50
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• 2000

본 논문에서는 R. T. Farouki에 의하여 소개된 평면 곡선들에 대한 복소수화된 표현법을 사용하여 주어진 임의의 평면 다항식 곡선을 복소수 계수를 갖는 한 다항식으로 나타내고 이 식을 대수학의 기본정리에 따라 복소수체 상에서 완전히 인수분해한 다음 그 근들을 관찰하여 주어진 곡선이 평면 다항식 피타고리안 호도그라프(PH) 곡선이 되기 위하 필요충분 조건을 새로운 방법으로 밝히고, 이를 3차원 민코브스키 공간 $R^{2,1}$ 상의 다항식 곡선에 적용, 이 곡선이 PH 곡선이 되기 위한 필요충분을 보다 간결한 형태로 나타내고 이를 통하여 3차원 민코브스키 공간 $R^{2,1}$ 상의 가능한 다항식 PH 곡선들의 유형이 모두 결정된다는 것을 보인다.