Earticle

This paper describes the use of approximation in Collaborative Optimization (CO) method, one of the Multidisciplinary Design Optimization (MDO) techniques. The approximation is used to model the result of a disciplinary design, optimal discrepancy function value, as a function of the interdisciplinary target variables passed from system level to the discipline. The optimal discrepancy function value is used to examine the interdisciplinary compatibility constraint (discrepancy function =0) duringthe system level optimization. However, the peculiar shape of the compatibility constraint makes it difficult to exploit well–developed conventional approximation methods. This paper introduces the combination of neural network classification and kriging to resolve this problem. In addition, for the purpose of enhancing the accuracy of the approximation, the approximation is continuously updated using the information obtained from the system level optimization. This iterative process is continued until acceptable convergence is achieved.

While piecewise geometric Brownian motion is a stochastic process that can effectively incorporate discrete dividends into stock prices without losing consistency, the process results in the lack of closed-form solutions for option prices. We aim to resolve this by providing analytical approximation formulas for American call option prices under this process. Our approximations include lower and upper bounds of the option prices. The additional numerical analysis indicates that the lower bound method is very efficient and it is possible to reduce the pricing error by considering additional terms.

일반적으로 게임 디자인 시에 웹과 같은 매체를 통해 구하거나 디자이너들이 디자인 툴로 제작한 3차원 기하 모델은 polygon soup 형태가 대부분이다. 따라서 이러한 polygon soup 모델은 일반적으로 완전한 매시로 가정해서 적용하는 여러 기법들을 적용할 수 없다. 이러한 문제를 해결하고 보다 매끈한 곡면을 얻기 위해서 MLS(Moving Least Squares) 방법을 점 단위가 아니라 삼각형 면 단위로 확장한 적분형 MLS 기법이 제안되었다. 그러나 이 기법은 본질적으로 전역(global) 계산의 한계로 인한 계산 속도의 한계가 불가피한 특징이 있었다. 본 논문에서는 분석적 해를 바탕으로 한 전역 계산 속도를 보다 가속화하기 위한 GPU 기반 병렬 기법을 제안하고 또한 기존 논문에서 충분히 논의하지 않았던 적분형 MLS 기법과 일반 MLS 기법의 차이점을 설명한다. 특히 GPU를 통한 가속 결과, 연산 정밀도의 감소없이 CPU 코어 1개로 계산하는 경우보다 평균 250배의 속도 향상을 얻을 수 있었다.

Most 3D models which are easily available on the Internet or designed by designers are polygon soups - they do not have topology information; some triangles are missing; or there exist some T-junctions. Due to this issue, it is often impossible to apply advanced geometry techniques to those polygon soups because most advanced methods assume that the 3D models are perfect manifold meshes. To address this problem, an integral MLS method which calculates integration, not summation over sample points to generate smooth implicit surfaces. However, those methods basically require global calculations for all the triangles so that it is very hard to accelerate the operations only with one CPU core. In this paper, we present a GPU-based parallelization technique for the analytic approach of the integral MLS method. Also, we discuss the difference between integral MLS and conventional one which was not fully explained in other papers. In our experiment, using GPU, we achieve that 250-fold speedup over the single CPU core.

In this article, we develop new upper and lower bounds on American option prices which improve the bounds by Broadie and Detemple. The main idea is the consideration of doubly capped call options which have two cap prices. We present a new option price approximation based on the two upper bounds. On average, our upper bound extrapolation (named UBE) has an average accuracy better than a 1,000 time-step binomial tree with a computation speed comparable to a 100 time-step binomial tree. We also provide a new method of approximating the optimal exercise boundaries of American options.

We herein propose a low-approximated least-squares method for underwater drone localization that does not require depth information. On the basis of error analysis, we propose a rule to deploy a set of surface drones that minimizes the impact of measurement errors such as GPS or distance measurement errors. The Evaluation results indicate that the proposed method outperforms the least-squares method when depth information is not provided.

This paper investigates the performance of millimeter-wave (mmWave) multicell networks with repulsively deployed base stations (BSs), via the β-Ginibre point process (β-GPP) where β adjusts the BS repulsion. In particular, this study analytically expresses the SINR distributions and validates the results via extensive simulations. Further, this paper empirically demonstrates that the effects of BS repulsion can be well modeled via linear regression (LR) and this LR-based approach can be also quite simply approximated as the convex combination (CC) of the two extreme cases of β→0 and β=1. Therefore, the proposed CC approximation can significantly reduce the time for calculating the SINR distributions in β-GPP mmWave multicell networks.

This paper suggests a variation of a well-known probabilistic matrix factorization algorithm which is commonly used in data analysis and scientific computing, and which has been considered recently to serve natural language processing. The proposed variation is meant to take benefit from the fact that matrices processed in natural language processing tasks are normally sparse rectangular matrices with one dimension much larger than the other, and this can be used to ensure adequate accuracy with acceptable computation time. Preliminary experiments on real-world textual corpora show that the proposed algorithm achieves relevant improvements compared to the original one.

This study proposes a robust hashing method using scale-invariant feature transform (SIFT) features points and discrete wavelet transform (DWT) approximation coefficients for image authentication. Initially, the invariant feature points are computed using SIFT from the component of color image. Next, n distinct SIFT feature points are utilized to extract image content from the component. Then, DWT is applied to extracted content in order to compute approximation coefficients. Finally, the approximation coefficients are normalized to form a binary hash. Experimental results show that the proposed method is robust to various content-preserving operations such as compression, scaling, filtering, additive noise, brightness, and contrast adjustment. In addition, the performance of the proposed method is compared to existing methods using a receiver operating characteristics curve. The comparison results show that the proposed method performs better than the existing methods.

La métaphore est un outil très employé dans les articles de divulgation du cancer dans la presse parce que les processus par rapport à l’origine et la dissémination de la maladie restent relativement inconnus. Comme la métaphore implique nécessairement un système de correspondances partielles entre domaines, aussi que l’adoption d’une perspective particulière, elle est étroitement liée à l’idéologie. Cette étude examine la dimension idéologique des métaphores du cancer dans la presse britannique et espagnole dans deux corpus comparables, chacun composé de 34 articles. Les métaphores utilisées ont été identifiées et analysées en tenant compte de l’emploi de relèvement et occultation avec chaque système figuratif. L’étude met en évidence 15 métaphores conceptuelles dans les corpus. La comparaison de ces métaphores permet d’établir des différences transculturelles. La moyenne est de 3 thèmes métaphoriques par texte dans le corpus anglais et de 3,6 dans le corpus espagnol. Les métaphores les plus fréquentes dans les deux corpus sont LE CANCER C’EST LA GUERRE, LES CELLULES CANCEREUSES SONT HUMAINES, LES CELLULES CANCEREUSES SONT DES MACHINES. Les tropes apparaissent combinés pour réaliser trois fonctions principales: attirer l’attention du lecteur, fonction explicative, et fonction structurelle. Certaines images sont aussi privilégiées selon l’aspect du cancer traité dans le texte.

In this paper the approximation methods of offset curve of conic with explicit error bound are considered. The quadratic approximation of conic(QAC) method, the method based on quadratic circle approximation(BQC) and the Pythagorean hodograph cubic(PHC) approximation have the explicit error bound for approximation of offset curve of conic. We present the explicit upper bound of the Hausdorff distance between the offset curve of conic and its PHC approximation. Also we show that the PHC approximation of any symmetric conic is closer to the line passing through both endpoints of the conic than the QAC.

In this paper, we used computerized glow curve deconvolution (CGCD) software with several models for the simulation of a TL glow curve which was used for analysis. By using the general approximation plus model, parameters values of the glow curve were analyzed and compared with the other models parameters (general approximation, mixed order kinetics, general order kinetics). The LiF:Mg,Cu,Si and the LiF:Mg,Cu,P material were used for the glow curve analysis. And we based on figure of merits (FOM) which was the goodness of the fitting that was monitored through the value between analysis model and TLD materials. The ideal value of FOM is 0 which represents a perfect fit. The main glow peak makes the most effect of radiation dose assessment of TLD materials. The main peak of the LiF:Mg,Cu,Si materials has a intensity rate 80.76% of the whole TL glow intensity, and that of LiF:Mg,Cu,P materials has a intensity rate 68.07% of the whole TL glow intensity. The activation energy of LiF:Mg,Cu,Si was analyzed as 2.39 eV by result of the general approximation plus(GAP) model. In the case of mixed order kinetics (MOK), the activation energy was analyzed as 2.29 eV. The activation energy was analyzed as 2.38 eV by the general order kinetics (GOK) model. In the case of LiF:Mg,Cu,P TLD, the activation energy was analyzed as 2.39 eV by result of the GAP model. In the case of MOK, the activation energy was analyzed as 2.55 eV. The activation energy was analyzed as 2.51 eV by the GOK model. The R value means different ratio of retrapping‐recombination. The R value of LiF:Mg,Cu,Si TLD main peak analyzed as 1.12 x 10‐6 and α value analyzed as 1.0 x 10‐3. The R of LiF:Mg,Cu,P TLD analyzed as 7.91 x 10‐4, the α value means different ratio of initial thermally trapped electron density‐initial trapped electron density (include thermally disconnected trap electrons density). The α value was analyzed as 9.17 x 10‐1 which was the difference from LiF:Mg,Cu,Si TLD. The deep trap electron density of LiF:Mg,Cu,Si was higher than the deep trap electron density of LiF:Mg,Cu,P.

국가간 유전능력평가를 위하여 5산차 다형질 모형을 적용한 다형질유효 딸소 기여도를 추정하기 위하여 농협중앙회 젖소개량부에서 수집한 한국형 보증종모우 및 수입 씨수소 2,046두의 딸소에대한 산유량 검정기록 및 관련된 혈통을 수집하였으며, 수집된 산유량 검정기록 중 산차는 5산차, 누적착유일은 75~307일로 제한하였고, 305일 보정유량이 15,000 kg이 넘는 기록은 국제평가기준에맞추기 위하여 제거하여, 총 301,551두 딸소의 681,860개 기록을이용하였다. EDC 계산을 위하여 모든 개체의 육종가 추정 신뢰도를 부모 육종가 평균 (Parents average), 개체의 기록(Yielddeviation) 및 배우자의 신뢰도가 보정된 후손의 육종가 기여도(Progeny contribution) 부분으로 분리하였으며, 1~5산차 유생산유전상관을 고려하여 다형질 유효 딸소 기여도를 추정하였다. 씨수소 2,046두의 유생산 기록을 가지는 딸소 두수의 산차별 평균은1~5산에서 각 140.57, 94.24, 55.14, 29.20 및 14.06두로 나타났으며, 추정된 MTEDC는 113.49, 89.28, 73.56, 54.02 및 35.08로 나타나 3산 이후의 기록이 부족함에도 유전상관을 고려한 EDC추정치는 높게 형성되어 검정자료의 활용도가 높아진 것을 확인하였다. 또한 EDC 계산은 국제유전능력평가 적용을 위한 필수항목으로 정확한 국제유전능력평가를 위해서는 관련 알고리즘에 대한이해가 필요하며, 지속적인 EDC 검증 및 종모우당 딸소 검정 두수 증가 등의 노력이 필요하다고 사료된다.

This study was conducted to investigate the basic concept of multiple trait effective daughter contribution(MTEDC) for dairy cattle sires and calculate effective daughter contribution(EDC) by applying a five lactation multiple trait model using milk yield test records of daughters for the Multiple-trait Across Country Evaluation(MACE). Milk yield data and pedigree information of 301,551 cows that were the progeny of 2,046 Korean and imported dairy bulls were collected from the National Agricultural Cooperative Federation and used in this study. For MTEDC approximation, the reliability of the breeding value was separated based on parents average, own yield deviation and mate adjusted progeny contribution. EDC was then calculated by lactation using these reliabilities. The average number of recorded daughters per sire by lactations were 140.57, 94.24, 55.14, 29.20 and 14.06 from the first to fifth lactation, respectively. However, the average EDC per sire by lactation using the five lactation multiple trait model was 113.49, 89.28, 73.56, 54.02 and 35.08 from the first to fifth lactation, respectively, while the decrease of EDC in late lactations was comparably lower than the average number of recorded daughters per sire. These findings indicate that the availability of daughters without late lactation records is increased by genetic correlation using the multiple trait model. Owing to the relatedness between the EDC and reliability of the estimated breeding value for sire, understanding the MTEDC algorithm and continuous monitoring of EDC is required for correct MACE application of the five lactation multiple trait model.

기존에는 속도식을 기초로 한 三輪의 식을 이용하여 대단히 복잡한 계산과정을 통하여 Bond의 분쇄일지수를 측정해 왔다. 분쇄일지수를 보다 단순하게 측정하기 위하여 기존의 三輪의 식 대신에 근사식인 石原의 식을 적용하여 분쇄일지수를 측정할 수 있는지를 검토하였다. 三輪의 식과 石原의 식으로부터 구한 분쇄일지수와의 값과 비교할 경우, 근사식인 石原의 식과 三輪의 식으로 구한 분쇄일지수는 2%의 오차 범위 내에서 일치하였다. 또한 石原의 식을 적용한 방법이 三輪의 식을 적용한 방법보다 단순하게 분쇄일지수를 계산할 수 있었으며, 石原에 의한 계산은 三輪의 계산에 비해 분쇄일지수의 계산과정을 현저하게 감소시킬 수 있었다. 국산 석탄의 분쇄 일지수는 순환비 및 분쇄능 실측 결과의 신뢰도를 고려해 볼 때 石原의 식과 三輪의 식을 적용 시 각각 약 12.85 kWh/ton 및 12.99 kWh/ton 으로 추정된다. 또한, 국산 규사의 분쇄 일지수는 순환비 및 분쇄능 실측결과의 신뢰도를 고려해 볼 때 石原의 식과 三輪의 식을 적용 시 동일하게 약 13.6 kWh/ton 으로 추정된다.

Generally Bond’s grinding work index has been measured complicatedly through the Miwa equation based on kinetic equation. This study is focused on the possibility of using Ishihara equation which is approximate equation instead of Miwa equation in order to measure grinding work index more simply. Grinding work index results from Ishihara equation and Miwa equation were in an error of less than 2 percent. Besides the procedure of Ishihara equation is minimized remarkably compared to that of Miwa equation. Considering reliability of circulation ratio and grindability, estimated grinding work indexes of domestic coal from Ishihara and Miwa equation are 12.85 and 12.99 kWh/ton respectively. And both grinding work indexes of domestic silica are 13.6 kWh/ton.

불균질 저류층의 유체 거동 특성을 정확하게 분석할 수 있는 다격자유량보정법(MPFA; Multi-Point Flux Approximation)과 유선기반 격자생성법을 결합한 업스케일링 기법을 개발하였다. 기존 격자생성법은 저류층의 수리학적 물성보다는 기하학적 특성에 초점을 맞춤으로써 비정규격자망에서 편향된 압력분포를 보일 위험이 있었다. 업스케일링법은 효율적 전산모사를 위해 도입되었으나 업스케일링 정도에 따라 유동모사의 정확도를 감소시키는 문제점이 있어, 유동모사의 효율성과 정확성을 모두 확보하는 격자생성법의 연구가 필요하다. 이 연구에서 개발한 격자생성법은 정규격자망에서 정확한 유동특징을 파악하기 위해 다격자유량보정법 조력 유선추적법과 빠른 비정규격자 재구성을 위해 딜로니(Delaunay) 삼각격자법을 통합하였다. 압력분포종횡비를 통해 압력계산의 정확도를 파악하고, 업스케일링 상수를 통해 업스케일링 효율성을 분석하였다. 균질 저류층의 경우 350개의 노드만으로 10,000개 노드를 가진 미세격자망의 수치정확도와 유사한 결과를 보였으며, 업스케일링 상수도 0.475로 기존 방법에 비해 효과적이었다. 비정규격자망 불균질 저류층의 경우, 압력값의 변동없이 업스케일링이 이루어졌을 뿐만 아니라 유체투과도의 평균, 표준편차, 변동계수 등의 통계변수가 비교적 잘 보존되었다. 이 연구의 격자생성법은 다양한 규모의 수리학적, 구조학적 특징을 결합할 수 있을 뿐만 아니라, 고해상도 저류층 모델의 업스케일링 효율성을 확보할 수 있을 것으로 기대된다.

A new upscaling approach by integrating MPFA (Multi-Point Flux Approximation) into a streamline-based mesh generator is presented to characterize flow transport accurately in a heterogeneous reservoir. Previous mesh generations have tended to cover the topological features rather than hydraulic ones and thereby they might result in a biased pressure distribution in an irregular grid-system. The upscaling schemes for more efficient simulation reduced the accuracy so that it was difficult to get both effects of efficiency and accuracy with one mesh generation. The method, developed in the study, incorporated streamline tracing in original structured grids, MPFA (Multi-Point Flux Approximation) for accurate flux-calculation and Delaunay triangular meshing for fast re-meshing. The aspect ratio examined the accuracy of pressure distribution and the upscaling coefficient investigated the effectiveness of the proposed scheme. Its applicability was verified in a homogeneous case to show the improved accuracy close to the result of fine grids with comparatively small number of nodes. The statistical properties like mean, standard deviation and coefficient of variation were conserved relatively well after upscaling a heterogeneous reservoir with unstructured quadrilateral meshes. The proposed method was able to combine different types of topological and hydraulic information, and offered effective means for generating subsurface flow models from highly detailed geological descriptions.

이 논문에서는 서로 다른 종류의 아이템들을 생산하기 위해서 필요한 템플릿을 구성하는 것과 관련된 일종의 패킹문제를 다룬다. 고정된 개수의 아이템이 배치된 하나 혹은 그 이상의 템플릿을 반복 인쇄함으로써 요구된 수량의 아이템들을 생산한다. 문제의 목적은 초과 생산량이 최소가 되도록 아이템들을 템플릿에 배치하는 것이다. 이 문제는NP-hard임이 밝혀져 있으며, 탐욕적 기법과 분기한정법에 기반한 근사 알고리즘이 알려져 있다. 본 논문에서는 이문제를 해결하기 위하여 잘 알려진 최적-적합 전략을 이용한 또 다른 다항시간 근사 알고리즘을 제시한다. 다양한실험 데이터를 통해 제시한 알고리즘의 성능을 평가하였으며 선행 연구에서 제시된 알고리즘과 비교하였다.

This paper deals with a kind of packing problem of which the goal is to compose one or more templates which will be used to produce the items of different types. Each template consists of a fixed number of slots which are assigned to the item types and the production of the items is accomplished by printing the template repeatedly. The objective is to minimize the total number of produced items. This problem is known to be NP-hard. Approximation algorithms based on either greedy approach or branch-and-bound technique have been proposed. We present another polynomial time approximation algorithm based on the well-known best-fit strategy. We perform experiments to compare the performance of the proposed algorithm with the previous ones.

라벨 패킹 문제는 고정된 개수의 라벨이 배치된 하나 혹은 그 이상의 템플릿을 반복 인쇄함으로써 라벨들을 생산할 때 초과 생산량이 최소가 되도록 템플릿을 구성하는 최적화 문제이다. 선행연구에서 이 문제가 NP-hard임이 밝혀 졌으며, 탐욕적 기법에 기반한 의사 다항시간의 근사알고리즘이 제안되었다[6]. 본 논문에서는 이 문제를 해결하기 위한 또 다른 근사 알고리즘을 제시한다. 먼저 3~4개 정도의 소수의 템플릿을 사용하는 경우에 대해서 최적 해를 찾는 분기한정법 탐색 알고리즘을 제시하고, 템플릿의 개수가 많을 경우 문제를 작은 규모의 부분 문제들로 분할하 여 해결하는 휴리스틱을 제시한다. 다양한 실험 데이터를 통해 제시한 알고리즘의 성능을 평가하였으며 선행 연구에 서 제시된 알고리즘과 비교하였다.

The label packing problem is to compose one or more templates each of which consists of a fixed number of labels of different types and print them multiple times to produce the required amount of labels. The goal is to minimize the over-produced quantities. In our earlier work [6], we proved that this problem is NP-hard and proposed an approximation algorithm based on greedy approach. In this paper, we present an improved approximation algorithm. We first give an optimal algorithm based on branch-and-bound search technique that is applicable when the number of template is a small constant. For the general cases where the number of templates is large, we partition the problem into small subproblems, solve each subproblem using the optimal algorithm, and then merge the results. We tested the algorithm for a variety of sample data and analyse its performance.