• 천문학회보
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• 제42권2호
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• pp.88.1-88.1
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• 2017

We report a novel design of the "linear astigmatism-free" three mirror system (LAF-TMS). In general, the linear astigmatism is one of the most dominant aberration degrading image qualities in common off-axis systems. The proposed LAF-TMS is based on a confocal off-axis three mirror system, where higher order aberrations are minimized via our numerical optimization. The system comprises three pieces of aluminum-alloy freeform mirrors that are feasible to be fabricated with current single-point diamond turning (SPDT) machining technology. The surface figures, dimensions, and positions of mirrors are carefully optimized for a LAF performance. For higher precision-positioning mechanism, we also included alignment parts: shims (for tilting) and L-brackets (for decentering). Any possible mechanical deformation due to assembly process as well as 1-G gravity, and its influence on optical performances of the system are investigated via the finite element (FE) analysis. The LAF-TMS has low f-number and a wide field of view, which is promising for sky monitoring programs such as supernova surveys.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권9호
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• pp.4567-4587
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• 2017

With the growth of the Internet and the extensive applications of image editing software, it has become easier to manipulate digital images without leaving obvious traces. Copy-move is one of the most common techniques for image forgery. Image blind forensics is an effective technique for detecting tampered images. This paper proposes an improved copy-move forgery detection method based on the discrete cosine transform (DCT). The quantized DCT coefficients, which are feature representations of image blocks, are truncated using a truncation factor to reduce the feature dimensions. A method for judging whether two image blocks are similar is proposed to improve the accuracy of similarity judgments. The main transfer vectors whose frequencies exceed a threshold are found to locate the copied and pasted regions in forged images. Several experiments are conducted to test the practicability of the proposed algorithm using images from copy-move databases and to evaluate its robustness against post-processing methods such as additive white Gaussian noise (AWGN), Gaussian blurring, and JPEG compression. The results of experiments show that the proposed scheme effectively detects both copied region and pasted region of forged images and that it is robust to the post-processing methods mentioned above.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권7호
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• pp.3076-3092
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• 2020

An IKPCA-ELM-based intrusion detection method is developed to address the problem of the low accuracy and slow speed of intrusion detection caused by redundancies and high dimensions of data in the network. First, in order to reduce the effects of uneven sample distribution and sample attribute differences on the extraction of KPCA features, the sample attribute mean and mean square error are introduced into the Gaussian radial basis function and polynomial kernel function respectively, and the two improved kernel functions are combined to construct a hybrid kernel function. Second, an improved particle swarm optimization (IPSO) algorithm is proposed to determine the optimal hybrid kernel function for improved kernel principal component analysis (IKPCA). Finally, IKPCA is conducted to complete feature extraction, and an extreme learning machine (ELM) is applied to classify common attack type detection. The experimental results demonstrate the effectiveness of the constructed hybrid kernel function. Compared with other intrusion detection methods, IKPCA-ELM not only ensures high accuracy rates, but also reduces the detection time and false alarm rate, especially reducing the false alarm rate of small sample attacks.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.983-999
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• 2014

The structural design of the ships includes two main issues which should be checked carefully, namely the extreme structural response (yielding & buckling) and the fatigue structural response. Even if the corresponding failure modes are fundamentally different, the overall methodologies for their evaluation have many common points. Both issues require application of two main steps: deterministic calculations of hydro-structure interactions for given operating conditions on one side and the statistical post-processing in order to take into account the lifetime operational profile, on the other side. In the case of ultra large ships such as the container ships and in addition to the classical quasi-static type of structural responses the hydroelastic structural response becomes important. This is due to several reasons among which the following are the most important: the increase of the flexibility due to their large dimensions (Lpp close to 400 m) which leads to the lower structural natural frequencies, very large operational speed (> 20 knots) and large bow flare (increased slamming loads). The correct modeling of the hydroelastic ship structural response, and its inclusion into the overall design procedure, is significantly more complex than the evaluation of the quasi static structural response. The present paper gives an overview of the different tools and methods which are used in nowadays practice.

• 한국태양에너지학회 논문집
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• 제36권3호
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• pp.25-31
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• 2016

Gaskets are usually used for the sealing of flange joints. The joint is usually composed of two flanges, a ring gasket and clamping bolts. The metal ring gasket is suitable for pipe flanges, pumps and valve joints in high temperature and high pressure environments. A very high surface stress is developed between a ring type joint gasket and the flange groove when the ring type joint is bolted up in a flange. The dimensions of flanges and ring joint gaskets for the pipe sizes that are in common use are specified in the ANSI codes. However, sometimes it is necessary to make a new design for the flange joint which is not specified in the codes, as the equipment is getting larger and larger in size. This paper presents the contact behavior of Class 600 ring joint gaskets with oval and octagonal cross sections. Five different sizes of gaskets are employed in the analysis, and one of them is newly designed on the basis of analysis results obtained from existing models. Three load steps are used to find the stress, stain and contact pressure etc., and to compare the contact characteristics among the models due to the bolt clamping force and the working surface pressure. ANSYS Workbench version15 is used to conduct the finite element analysis.

• The Journal of Asian Finance, Economics and Business
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• 제7권11호
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• pp.843-851
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• 2020

This study focuses on identifying and prioritizing the broader performance measures for the service supply chains by taking the case of Majan Electricity Company, Sohar, in the Sultanate of Oman. For an examination of the uniformity of ultimate objectives and the priorities therein, two strata of respondents with a total of fourteen respondents were approached for their valuable insights. Suitable structured instruments were personally administered to elicit the insightful and worthy responses. The two multi-criteria decision-making techniques, namely, the Fuzzy Analytical Hierarchy Process and the Best-Worst Method were used to reach a meaningful prioritization of the identified and refined broader performance measurement dimensions. The results show that there exists a minor gap between the two respondents' groups in terms of their prioritizations. The major finding points to the difference in terms of the topmost priorities as revealed by the two set of respondents. For one group of respondents, the customer satisfaction matters the most, whereas for the other group, it is the overall profitability that matters the most. This gap against the utopian state assists in concluding that there is a requirement to reorient the employees so as to have a shared and common understanding of the organizational priorities.

• 한국의류산업학회지
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• 제10권3호
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• pp.289-297
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• 2008

This paper was to examine the salesperson's service that the consumer demands in different types of fashion retailing formats including department store, discount store and outlet store. Data has been collected from June to August in 2005 in Pusan and Seoul on subject of 1000 adult over18 years old and 979 pieces were used to analyze. Data analysis was conducted by factor analysis, regression using the SPSS statistics package program. Services in common in 3 fashion retailing formats were "individual concerning", "kindness, courtesy/customer respect", "quick correspondence/convenience", and "product knowledge". Unique services that consumer demanded for the department store were professional and polite attitude; for the discount store, honesty and convenience for refund and exchange; for the outlet store, wide range of product selection. The results has shown that the part of salesperson's service dimensions influenced the consumer's purchase, repurchasing intention and the level of satisfaction. Therefore fashion marketers need to carefully implicate operation and service management depending on the retailing formats.

• 한국언론정보학보
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• 제59권
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• pp.92-115
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• 2012

조선 후기 대항 공론장의 특성을 분석하고자 역사적, 규범적, 분석적 차원으로 나누어 검토하였다. 그 결과, 당시 민(民)을 중심으로 형성된 대항 공론장은 반(半)봉건 반(反)외세적 성격을 띤 하부 공론장의 역할을 함을 발견하였다. 즉, 조선 후기의 대항 공론장은 당시 정치사회적 환경을 극복하고, 생존의 문제를 해결코자 한 반(半)봉건 반(反)외세적 성향이 가진 생동적인 공론장이었다. 그러나 이러한 조선 후기 대항 공론장은 지속성을 유지하지 못했다. 하지만 이후 항일운동의 발판이 되었고, 나아가서는 오늘날 민중운동의 이념적 근거가 되었다는 것에 그 의의가 있다고 할 수 있다.

• 한국의류학회지
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• 제23권2호
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• pp.335-342
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• 1999

This study is aimed at providing useful data which can be utilized for the design of their dress forms and enhancing the fitness of their apparels. To this end 330 pre-school children living in the capital area and aged from 4 to 6 were sampled to be subject to the measurement of their somatotypes. The results of this study can be summarized as follows ; 1 By the analysis of overlapped cross section diagram and silhouette diagram of each somatotype both had a common shape of lean-backed upper troso. 2. The type 1 showed less dimensions in most scales than type 2 while their shoulder were less developed. The type 2 showing more development in each element. 3. As a result of comparing the dress forms designed in reference with classified somatotypes and the commercial ones it was found that the former ones had the upper body part slanted slightly backwards and the belly part extruded forwards while the latter had a straight posture with large shoulder parts. After all the commercial dress forms were found not to reflect the actual somatotypes of Pre-School children's.

• Communications for Statistical Applications and Methods
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• 제23권3호
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• pp.259-268
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• 2016

High-dimensional survival data with large numbers of predictors has become more common. The analysis of such data can be facilitated if the dimensions of predictors are adequately reduced. Recent studies show that a method called sliced inverse regression (SIR) is an effective dimension reduction tool in high-dimensional survival regression. However, it faces incapability in implementation due to a double categorization procedure. This problem can be overcome in the right-censoring type by transforming the observed survival time and censoring status into a single variable. This provides more flexibility in the categorization, so the applicability of SIR can be enhanced. Numerical studies show that the proposed transforming approach is equally good to (or even better) than the usual SIR application in both balanced and highly-unbalanced censoring status. The real data example also confirms its practical usefulness, so the proposed approach should be an effective and valuable addition to usual statistical practitioners.