• 한국음향학회지
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• 제7권2호
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• pp.65-73
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• 1988

본 논문에서는 음향현미경의 V(z)곡선을 해석하고 실험결과와 비교 고찰하였으며 V(z)곡선과 재료의 탄성 특성사이의 관계를 연구분석하였다. V(z)곡선의 이론적인 해석은 angular spectrum과 ray optics 이론을 사용하였고 실험은 동작주파수가 3MHz인 음향현미경을 구성하여 행하였다. 실험결과 V(z)곡선은 재료마다 고유의 형태를 나타내며 V(z) 곡선에서 극대치 사이의 간격은 재료에서 Rayleigh 파의 음향속도를 산출하는 데 이용될 수 있음을 보였다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제5권3호
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• pp.263-267
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• 2005

Building classifiers for financial real-world classification problems is often plagued by severely overlapping and highly skewed class distribution. New performance measures such as receiver operating characteristic (ROC) curve and area under ROC curve (AUC) have been recently introduced in evaluating and building classifiers for those kind of problems. They are, however, in-effective to evaluation of classifier's discrimination performance in a particular class of the classification problems that interests lie in only a local operating range of the classifier, In this paper, a new method is proposed that enables us to directly improve classifier's discrimination performance at a desired local operating range by defining and optimizing a partial area under ROC curve or domain-specific curve, which is difficult to achieve with conventional classification accuracy based learning methods. The effectiveness of the proposed approach is demonstrated in terms of fraud detection capability in a real-world fraud detection problem compared with the MSE-based approach.

• 산업경영시스템학회지
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• 제5권6호
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• pp.69-78
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• 1982

Traditional CVP (Cost-Volume-Profit) analysis employs linear cost and revenue functions within some specified time period and range of operations. Therefore CVP analysis is assumption of constant labor productivity. The use of linear cost functions implicity assumes, among other things, that firm's labor force is either a homogenous group or a collection homogenous subgroups in a constant mix, and that total production changes in a linear fashion through appropriate increase or decrease of seemingly interchangeable labor unit. But productivity rates in many firms are known to change with additional manufacturing experience in employee skill. Learning curve is intended to subsume the effects of all these resources of productivity. This learning phenomenon is quantifiable in the form of a learning curve, or manufacturing progress function. The purpose d this study is to show how alternative assumptions regarding a firm's labor force may be utilize by integrating conventional CVP analysis with learning curve theory, Explicit consideration of the effect of learning should substantially enrich CVP analysis and improve its use as a tool for planning and control of industry.

• 국제물리치료학회지
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• 제9권2호
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• pp.1513-1516
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• 2018

The purpose of this study was to identify the effect of upper thoracic mobilization on cervical alignment in stroke patients with forward head posture. The subject's of this study were two stroke patients with forward head posture and a cervical curve angle (four-line Cobb's method; FLCM) less than $40^{\circ}$. The intervention, central posterior-anterior (PA) mobilization, was applied to the T1-T4 vertebrae (upper thoracic spine) following the Maitland concept. This mobilization was applied three times per week for four weeks. In the results, the cervical curve angle (FLCM) increased for both subject 1 and 2. However, Jochumsen method score was decreased in subject 1, while it was increased in subject 2. These results demonstrate that upper thoracic mobilization had the positive effect on the cervical curve angle but not on Jochumsen method score. These findings suggest that PA mobilization on the upper thoracic spine could correct cervical curve angle measured by FLMC in stroke patients with FHP.

• 열처리공학회지
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• 제32권1호
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• pp.17-28
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• 2019

Jominy hardenability curves of low alloy steel containing less than 5 wt.% of alloying elements in total were calculated by applying Scheil's rule of additivity to pre-calculated isothermal transformation curve. Isothermal transformation curve for each phase in steel was approximated as a simple mathematical equation by using Kirkaldy's approach and all coefficients in the equation were estimated from experimental temperature-time-transformation (TTT) and/or continuous cooling transformation (CCT) data in the literature. Then jominy test with simple boundary conditions was performed in computer by applying the finite difference scheme. The resultant cooling curves at each location along a longitudinal direction of Jominy bar were applied to calculate phase fractions as well as mechanical properties such as micro Vickers hardness. The simulated results were compared with experimental CCT data and Jominy curves in the literature.

• International Journal of Computer Science & Network Security
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• 제21권3호
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• pp.60-70
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• 2021

In this paper we study the problem of implementation of security issues of blue tooth, especially secure simple pairing, with the help of an efficient four user authenticated key (4UAK) for an elliptic curve cryptography (ECC). This paper also deals with the design, implement and performance evaluation of secure simple pairing (SSP) using an elliptic curve cryptography, such as Diffie Hellman protocol when four users are involved. Here, we also compute the best, worst and average case step counts (time complexities). This work puts forth an efficient way of providing security in blue tooth. The time complexity of O(n⁴) is achieved using Rabin Miller Primality methodology. The method also reduces the calculation price and light communication loads.

• 한국과학교육학회지
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• 제35권1호
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• pp.121-130
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• 2015

국가 수준의 표준화된 학업 성취도 평가 결과를 분석하여 학생들의 성취 수준을 파악하고 이를 교육정책 수립이나 교수활동 개선에 반영하는 과정은 교육의 책무성으로 중요한 부분이다. 본 연구에서는 과학과 국가 수준 학업 성취도 평가 결과를 분석하고, 답지 반응률 분포 곡선을 활용하여 평가 문항의 특성을 분석하고자 하였다. 이를 위해 2010년부터 2013년까지 시행된 과학과 성취도 평가 결과를 성취 수준에 따라 분석하였으며, 성취도 점수에 따른 특정 문항의 정오답 반응률을 토대로 최적 곡선을 추정한 그래프인 답지 반응률 분포 곡선을 활용하여 선다형 평가 문항 112개의 정답지와 오답지 반응률 곡선의 유형을 분류하고, 유형별 문항 특성을 분석하였다. 분석 결과, 정답지는 5가지 유형(S자형, J자형, 직선형, F자형, 계단형)으로 분류하였고, 오답지는 4가지 유형(보통형, 평지형, 산지형, 상승형)으로 분류하였다. S자형의 정답지 반응 곡선과 보통형의 오답지 반응 곡선이 조합인 문항이 가장 많았으며, 성취 수준에 따라 학생들을 변별하는데 적절한 문항인 것으로 분석되었다. 또한, 정답 반응률 분포와 오답 반응률 분포가 서로 연관되는 것으로 나타났다. 연구 결과를 토대로 교수 학습, 교실 평가 등에서 함의를 논의하였다.

• 복식
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• 제50권2호
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• pp.167-182
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• 2000

The purpose of this study is to examine the art nouveau fashion represented in the end of the twentieth century. The characteristics of art nouveau are naturalism, medievalism , exoticism, and decadentism. The influences of art nouveau were seen in the fashion of the late nineteenth century : S-curve silhouette and organic curve motives printed on hems. Art nouveau has reappeared in modern fashion trends such as romanticism , decadence, ecology, ethno, and fusion. To sum up, art nouveau fashion at the end of the twentieth century is classified into four shapes. First, art nouveau appears in naturalism. Influenced by the arts and crafts movements and naturalistic trend, it has reappeared at the end of the twentieth century in themes like 'art & craft'. This expression technique is to objectively nature and to represented art nouveau textiles. Second, S-curve silhouette appeared at the end of nineteenth century's fashion with the art nouveau influenced rejection of the bustle style. At the end of the twentieth century, the design , emphasizing the hip, is represented in fashion collections as a phenomenon of romanticism . Especially the art nouveau silhouette of the end of the twentieth century does not represent S-curve silhouette. But , it emphasizes the hip only. Third, Art nouveau exoticism by symbolism is influenced by Chinese and Celtic art, the Middle Ages, and the exoticism that appeared in fashion at the end of the nineteenth century : harem style, kimono style, and turbans. Exoticism at the end of the twentieth century is expressed by optical flower prints and successive floral print arrangements as seen in the themes of ethno and fusion. Fourth, one of the characteristics of art nouveau, decadence is influenced by the pre-raphaelite brotherhood. This is expressed in the images of vampires, and symbolism expressing grotesque insect motives and decadent successive curves. At the end of the twentieth century decadence is represented in fashion ; grotesque insect motives, tatto looks of organic curve motives celtic hair style, see-through fashion, grotesque make-up . Besides hair style techniques, decadent expressions applying art nouveau paintings also appeared. Finally , art nouveau fashion represented as a fashion trend at the turning point to the new millennium is one of great significance as an organic, an environment-intimate and continuance-possible design in a future.

• 한국화재소방학회논문지
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• 제28권5호
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• pp.44-51
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• 2014

본 연구에서는 건축물에서의 성능기반 화재안전 설계 시에 사용되는 구획공간에서의 화재 성상 분석을 위해서 사무실 공간을 대상으로 하여 $2.4(L){\times}3.6(W){\times}2.4(H)m$의 크기의 구획 Mock-up을 제작하고 구획 내부에는 화재하중 $18.74kg/m^2$을 적용하여 책상, 의자, 컴퓨터 등과 같은 실제 가연물을 배치하여 화재실험을 실시하였다. 화재실험 결과, 구획 공간의 내부 중앙에서는 394~408 s 사이에 $600^{\circ}C$에 도달하였고 구획 입구 모서리에서는 404~420 s 사이에 $600^{\circ}C$에 도달하였다. 본 연구에서는 화재실험을 통해 측정된 온도변화 데이터를 BFD 곡선에 적용하여 화재시 구획 공간내의 온도변화 예측 기법을 분석하고자 하였으며, 화재실험을 통해 BFD 곡선 인자는 최대온도 $900^{\circ}C$, 최대온도 도달시간 7분과 형태계수 1.5로 결정하였다. BFD 곡선에 적용된 사무실 공간의 시간에 따른 온도 곡선은 화재초기에 빠르게 상승한 이후에 약 9분경 이후에 감소하는 형태를 나타내고 있다.

• 대한수학회지
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• 제54권4호
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• pp.1331-1343
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• 2017

A curve ${\gamma}$ immersed in the three-dimensional sphere ${\mathbb{S}}^3$ is said to be a slant helix if there exists a Killing vector field V(s) with constant length along ${\gamma}$ and such that the angle between V and the principal normal is constant along ${\gamma}$. In this paper we characterize slant helices in ${\mathbb{S}}^3$ by means of a differential equation in the curvature ${\kappa}$ and the torsion ${\tau}$ of the curve. We define a helix surface in ${\mathbb{S}}^3$ and give a method to construct any helix surface. This method is based on the Kitagawa representation of flat surfaces in ${\mathbb{S}}^3$. Finally, we obtain a geometric approach to the problem of solving natural equations for slant helices in the three-dimensional sphere. We prove that the slant helices in ${\mathbb{S}}^3$ are exactly the geodesics of helix surfaces.