• 대한수학회논문집
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• 제11권4호
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• pp.1187-1192
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• 1996

It is known that an unbiased estimator of f(p) for binomial B(n,p) exists if and only if f is a polynomial of degree at most n, in which case the unbiased estimator of a real-valued function $f(p), p = (p_0,p_1,\cdots,p_r)$ is unique. In general, this estimator has the serious fault of not being range preserving; that is, its value may fall outside the range of f(p). In this article, a condition on a real-valued function f is derived that is necessary for the unbiased estimator to be range preserving that this is sufficient when n is large enough.

• 대한수학회보
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• 제52권6호
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• pp.1963-1971
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• 2015

Let $\mathcal{A}$ and $\mathcal{B}$ be two unital $C^*$-algebras. Denote by W(a) the numerical range of an element $a{\in}\mathcal{A}$. We show that the condition W(ax) = W(bx), ${\forall}x{\in}\mathcal{A}$ implies that a = b. Using this, among other results, it is proved that if ${\phi}$ : $\mathcal{A}{\rightarrow}\mathcal{B}$ is a surjective map such that $W({\phi}(a){\phi}(b){\phi}(c))=W(abc)$ for all a, b and $c{\in}\mathcal{A}$, then ${\phi}(1){\in}Z(B)$ and the map ${\psi}={\phi}(1)^2{\phi}$ is multiplicative.

• 기록학연구
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• 제31호
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• pp.139-161
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• 2012

Donald K. Sebera 모델은 다른 열화인자의 영향을 고려하지 않고 오직 온도와 습도만의 변화를 이용하여 두 개 이상의 서고환경에 대한 보존성 평가지수를 계산함으로서 기록물의 보존환경을 정량적으로 비교 평가하는데 활용될 수 있다. 본 연구에서는 Donald K. Sebera 모델을 이용하여 기록물관리법에서 제시하고 있는 온 습도 범위에서 종이기록물 보존조건 중 가장 우수한 조건과 가장 열악한 조건에서의 보존성을 비교 분석하였다. 그 결과 기록물관리법에서 허용하고 있는 온 습도 범위 내에서 보존조건이 가장 우수한 조건에서의 종이기록물 보존성 평가지수가 가장 열악한 조건에서 보다 2.47배 더 큰 것으로 나타났다. 또 가수분해반응 활성화에너지가 작을수록 종이기록물의 보존성은 온도보다는 습도에 의한 영향력이 크게 작용하였다. 따라서 보존성 평가지수는 서고의 온 습도 조건이 기록물 보존환경에 적합한지를 쉽게 판단할 수 있기 때문에 온 습도 변화에 대해 보존성 확보가 가능한 도구로 유용하게 활용될 수 있다.

• 대한수학회논문집
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• 제30권4호
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• pp.349-361
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• 2015

A fence is an ordered set that the order forms a path with alternating orientation. Let F = (F;${\leq}$) be a fence and let OT(F) be the semigroup of all order-preserving self-mappings of F. We prove that OT(F) is coregular if and only if ${\mid}F{\mid}{\leq}2$. We characterize all coregular elements in OT(F) when F is finite. For any subfence S of F, we show that the set COTS(F) of all order-preserving self-mappings in OT(F) having S as their range forms a coregular subsemigroup of OT(F). Under some conditions, we show that a union of COTS(F)'s forms a coregular subsemigroup of OT(F).

• 대한수학회보
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• 제33권1호
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• pp.1-16
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• 1996

Earlier in 1935[12], M. S. Robertson introduced the class of quadrant preserving functions. More precisely, let Q be the class of all functions f(z) analytic in the unit disk $D = {z : $\mid$z$\mid$ < 1}$ such that f(0) = 0, f'(0) = 1, and the range f(z) is in the j-th quadrant whenever z is in the j-th quadrant of D, j = 1,2,3,4. This class Q contains the subclass of normalized, odd univalent functions which have real coefficients. On the other hand, this class Q is contained in the class T of odd typically real functions which was introduced by W. Rogosinski [13]. Clearly, if $f \in Q$, then f(z) is real when z is real and therefore the coefficients of f are all real. Recently, it was observed by Y. Abu-Muhanna and T. H. MacGregor [1] that any function $f \in Q$ is odd. Instead of functions "preserving quadrants", the authors [1] have introduced the notion of "preserving sectors".

• Journal of Information Processing Systems
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• 제15권5호
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• pp.1211-1217
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• 2019

Developing methods to search over an encrypted database (EDB) have received a lot of attention in the last few years. Among them, order-revealing encryption (OREnc) and order-preserving encryption (OPEnc) are the core parts in the case of range queries. Recently, some ideally-secure OPEnc schemes whose ciphertexts reveal no additional information beyond the order of the underlying plaintexts have been proposed. However, these schemes either require a large round complexity or a large persistent client-side storage of size O(n) where n denotes the number of encrypted items stored in EDB. In this work, we propose a new construction of an efficient OPEnc scheme based on an OREnc scheme. Security of our construction inherits the security of the underlying OREnc scheme. Moreover, we also show that the construction of a non-interactive ideally-secure OPEnc scheme with a constant client-side storage is theoretically possible from our construction.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2018년도 추계학술대회
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• pp.124-127
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• 2018

넓은 동적 영역 (High Dynamic Range: HDR) 이미지는 주관적 화질 측면에서 우수하지만 대부분의 디스플레이는 좁은 동적 영역 (Low Dynamic Rang e: LDR) 만 지원이 가능하다. 본 논문에서는 이를 해결하기 위해서 톤 매핑 기법 (Tone Mapping Operator: TMO) 을 사용하여 넓은 동적 영역을 압축하여 수행한다. 기존의 지역 에지 보존 (Local Edge Preserving: LEP) 필터를 적용한 이미지결과는 에지를 보존하지만, 스케일의 분해 과정 중 디테일의 손실이 발생되었다. 본 논문에서는 이미지 변화도를 기반으로 디테일을 보존하는 알고리듬을 제안한다. LEP 필터가 적용되기 전에 이미지의 변화도와 동적 영역이 압축된 후의 이미지에 대한 변화도의 차이만큼 가중하여 디테일을 보존함으로써 주관적 화질을 향상시켰다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제15권1호
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• pp.35-44
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• 2015

The main purpose of image enhancement is to improve certain characteristics of an image to improve its visual quality. This paper proposes a method for image contrast enhancement that can be applied to both medical and natural images. The proposed algorithm is designed to achieve contrast enhancement while also preserving the local image details. To achieve this, the proposed method combines local image contrast preserving dynamic range compression and contrast limited adaptive histogram equalization (CLAHE). Global gain parameters for contrast enhancement are inadequate for preserving local image details. Therefore, in the proposed method, in order to preserve local image details, local contrast enhancement at any pixel position is performed based on the corresponding local gain parameter, which is calculated according to the current pixel neighborhood edge density. Different image quality measures are used for evaluating the performance of the proposed method. Experimental results show that the proposed method provides more information about the image details, which can help facilitate further image analysis.

• Journal of Korean Neurosurgical Society
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• 제49권5호
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• pp.308-313
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• 2011

Posterior cervical foraminotomy is an attractive therapeutic option in selected cases of cervical radiculopathy that maintains cervical range of motion and minimize adjacent-segment degeneration. The focus of this procedure is to preserve as much of the facet as possible with decompression. Posterior cervical inclinatory foraminotomy (PCIF) is a new technique developed to offer excellent results by inclinatory decompression with minimal facet resection. The highlight of our PCIF technique is the use of inclinatory drilling out for preserving more of facet joint. The operative indications are radiculopathy from cervical foraminal stenosis (single or multilevel) with persistent or recurrent root symptoms. The PCIFs were performed between April 2007 and December 2009 on 26 male and 8 female patients with a total of 55 spinal levels. Complete and partial improvement in radiculopathic pain were seen in 26 patients (76%), and 8 patients (24%), respectively, with preserving more of facet joint. We believe that PCIF allows for preserving more of the facet joint and capsule when decompressing cervical foraminal stenosis due to spondylosis. We suggest that our PCIF technique can be an effective alternative surgical approach in the management of cervical spondylotic radiculopathy.

• 방송공학회논문지
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• 제14권4호
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• pp.428-437
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• 2009

A high dynamic range (HDR) image can represent real world scenes that have a wide range of luminance intensity. However, compared with the range of real world luminance, conventional display devices have a low dynamic range (LDR). To display HDR images onto conventional displayable devices such as monitors and printers, we propose the logarithmic based global reproduction algorithm that considers the features of the image using reproduction parameters. Based on the characteristics of the image, we first modify the input luminance values for reproducing perceptually tuned images and then obtain the displayable output values directly. The experimental results show that the proposed algorithm achieves good subjective results while preserving details of the image; furthermore, the proposed algorithm has a fast, simple and practical structure for implementation.