Earticle

In this paper, a hybrid method is proposed to design an air-core superconducting solenoid system for 6 T axial uniform magnetic field using Niobium Titanium (NbTi) superconducting wire. In order to minimize the volume of conductor, the hybrid optimization method including a linear programming and a nonlinear programming was adopted. The feasible space of solenoid is divided by several grids and the magnetic field at target point is approximated by the sum of magnetic field generated by an ideal current loop at the center of each grid. Using the linear programming, a global optimal current distribution in the feasible space can be indicated by non-zero current grids. Furthermore the clusters of the non-zero current grids also give the information of probable solenoids in the feasible space, such as the number, the shape, and so on. Applying these probable solenoids as the initial model, the final practical configuration of solenoids with integer layers can be obtained by the nonlinear programming. The design result illustrates the efficiency and the flexibility of the hybrid method. And this method can also be used for the magnet design which is required the high homogeneity within several ppm (parts per million).

본 연구는 기후변화로 초래될 수 있는 가뭄의 경제적 파급효과를 추정하고자 하였다. 아직 우리나라에는 수자원분야의 표준 시나리오가 없기 때문에 인위적으로 물부족을 가정하였으며, 분석은 수자원 투입산출 선형계획법(WIOLP)을 사용하였다. 추정결과, 경제내 필요한 수자원량 중 10%가 감소할 경우, 경제에 주는 피해액은 약 6조 4천억원으로 추정되었으며 물의 부족량에 따라 수자원의 잠재가격은 2,462원에서 76,902원까지 증가하는 것으로 추정되었다. 본 연구결과는 가뭄 등으로 인해 용수의 제약이 발생할 경우, 경제전체에 미치는 파급효과는 매우 클 수 있다는 것을 의미하며 수자원 관리의 필요성을 반영한다.

This study is to estimate economic damages of water shortage, especially drought. we assume scenarios of water shortage and use water input-output linear programming. The result is that economic damage is about 6.4 trillion won in the case of 10% water shortage. According to water shortage scenarios, the shadow price of water in Korea is increasing from 2,462 won to 76,902 won. This study indicates that water has a significant influence on the industrial production in Korea and provides the necessity of the climate change policy for water management.

Interest is increasing in electrocardiogram (ECG) signal analysis for embedded devices, creating the need to develop an algorithm suitable for a low-power, low-memory embedded device. Linear approximation of the ECG signal facilitates the detection of fiducial points by expressing the signal as a small number of vertices. However, dynamic programming, a global optimization method used for linear approximation, has the disadvantage of high complexity using memoization. In this paper, the calculation area and memory usage are improved using a linear approximated template. The proposed algorithm reduces the calculation area required for dynamic programming through local optimization around the vertices of the template. In addition, it minimizes the storage space required by expressing the time information using the error from the vertices of the template, which is more compact than the time difference between vertices. When the length of the signal is L, the number of vertices is N, and the margin tolerance is M, the spatial complexity improves from O(NL) to O(NM). In our experiment, the linear approximation processing time was 12.45 times faster, from 18.18 ms to 1.46 ms on average, for each beat. The quality distribution of the percentage root mean square difference confirms that the proposed algorithm is a stable approximation.

본 연구는 국내 산업용수 이용량과 산업연관표를 연계하여 물 투입-산출 모형을 설정하고, 선형계획 법을 이용해 산업 부문(농업, 공업, 서비스업)별 수자원의 잠재가격을 추정하였다. 물 이용량과 산업 연관표 간의 통합을 위해 연동이 가능한 2014년 최근 자료(수자원통계 및 한국은행 산업연관표)를 적용하였으며, 산업용수 이용 업종 분류 체계에 맞추어 산업연관표의 30개 대분류를 12개 산업 부문 으로 재정의하였다. 각 부문별 물 투입 계수를 포함한 물 투입산출표를 설정한 뒤, 가용 수자원량과 업종 간 생산관계의 제약 속에서 각 용수의 잠재가격과 물 부족 시나리오에 따른 부문별 잠재가격 변화를 추정하였다. 주요 결과는 다음과 같다. 농업용수, 공업용수, 서비스업용수의 잠재가격은 각각 864원/㎥, 27,545원/㎥, 275,449원/㎥로 나타났으며, 물 부족 시나리오에 따른 잠재가격 변화 범위 (10% 제약~90% 제약)는 농업용수가 1,518원/㎥ ~ 2,369원/㎥, 공업용수가 61,721원/㎥ ~ 997,092원/㎥, 서비스업용수가 294,923원/㎥ ~ 381,192원/㎥이었다. 특히, 공업부문의 피해 수준이 50% 제약 수준에 서 급격히 증가된다는 점을 확인하였다.

This study set the water input-output model by linking the amount of water use to inter-industry relations table (IRT), and estimated shadow prices of water resources in agricultural, industrial and service sector using linear programming method. The 2014 water data and IRT data were collected and linked for integration of water usage and input-output table, and 30 major categories of IRT were redefined into 12 sub-sectors. Using the data, the shadow prices and their changes in each sector were estimated according to drought scenarios. The main results derived from the water input-output linear programming are as follows. Shadow prices of agriculture water, industrial water and service industry water were 864 won/㎥, 27,545 won/㎥ and 275,449 won/㎥ respectively. The shadow price changes by water shortage (10% to 90% constraint) ranged from 1,518 to 2,369 won/㎥ for agricultural use, 61,721 to 997,092 won/㎥ for industrial use, and 294,923 to 381,192 won/㎥ for service industry. In particular, it was confirmed that the damage level in the industrial sector increased sharply at the 50% restriction level.

퍼지 선형계획법은 불확실성하에서의 문제들을 해결하는데 유용한 의사결정 모형이다. 본 연구에서는 목 적함수 값이 퍼지수이고 우변 상수도 퍼지수인 융합 등식 제약식을 갖는 퍼지 선형계획법 문제를 다룬다. 연구의 목적은 퍼지 해를 정의하고 그것을 구하는 절차를 모색하는 것이다. 목적함수 값에 대한 소속 함수로 부분 선형함수 를, 제약식의 소속 함수로는 사다리꼴 함수를 도입한다. 사다리꼴 함수는 구간별 선형 함수 들로 나누어 나타낼 수 있다. 따라서 모든 소속 함수들을 선형식 들로 대체함으로써 퍼지 선형계획 모형을 Zimmermann의 대칭 선형 모형 으로 바꿀 수 있다. 여기에 최대-최소 기준을 적용하여 일반 선형계획법 문제를 도출해 내고, 이 문제의 최적해로부 터 원 문제의 퍼지 해를 얻게 된다. 본 논문에서는 사다리꼴 소속 함수에 대해 살펴보았는데 앞으로는 오목 부분 선형함수와 같은 좀 더 일반화된 소속 함수에 대한 연구가 필요하다.

The fuzzy linear programming(FLP) is the useful approach to many real world problems under uncertainty. This paper deals with a FLP whose objective value is fuzzy. And the right hand sides of convergent equality constraints are fuzzy numbers. We assume that the membership function of the objective value is piecewise linear and those of the right hand side are trapezoidal. Each of these trapezoidal functions can be algebraically replaced with three linear functions. Then the FLP problem is transformed into the Zimmermann's symmetric model. The fuzzy solution based on the max-min rule can be obtained by solving the crisp linear programming problem derived from the symmetric model. A numerical example has illustrated our approach. The application of our approach to the inconsistent linear system can enable generate us to get define the useful and flexible inexact solutions within acceptable tolerance. Further research is required to generalize the membership function.

본 연구에서는 지능형 정수장 운영시스템 개발 연구의 일환으로 선형계획법(Linear Programming, LP)을 이용한 정수장 취수계획 최적화 모형을 개발하였다. 개발된 최적화 모형은 원수의 정수처리비용의 최소화를 목적함수로 설정하였으며, 취수 후 정수처리에 소요되는 지연시간과 시간별 전력단가를 고려하여 취수가능량, 예측수요량, 정수지 운영수위 등의 제약조건을 만족하는 최적 취수계획을 제시하였다. 국내 H 정수장을 대상으로 경제적이고 안정적인 정수장 운영을 위해 세 가지 최적화 전략을 적용하고, 그 결과를 경제성과 안정성 측면에서 비교, 분석하였다. 개발 모형은 국내 정수장의 보다 효율적인 취수계획 수립을 위한 의사결정 지원시스템의 형태로 실무에서 활용이 가능할 것으로 기대된다.

An optimization model of water intake planning is developed based on a linear programming (LP) for the intelligent water purification plant operation system. The proposed optimization model minimizes the water treatment costs of raw water purification by considering a time-delay of treatment process and hourly electricity tariff, which is subject to various operation constraints, such as water intake limit, storage tank capacity, and water demand forecasts. For demonstration, the developed model is applied to H water purification center. Here, we have tested three optimization strategies and the results are compared and analyzed in economic and safety aspects. The optimization model is expected to be used as a decision support tool for optimal water intake scheduling of domestic water purification centers.

본 논문은 여러개의 복합호우 자료로써 선형계획법에 의한 대표단위도를 유도하는 앨고리즘을 제공한다. 주어진 한 유역에서 종전의 방법은 여러 호우사상에 대해서 각각 단위도를 유도하여 첨두유량 및 시간에 대한 특성치 평균법을 썼다. 본 연구에서 사용한 LP모형은 Mays 등이 제안한 모형을 다음과 같이 수정하였다. 목적 함수는 가중치를 부여한 잔차의 합의 최소화로 설계하였고, Mays 논문에서 실제로는 적용하지 않은 부등호 제약보다 더 적극적인 2점 이동평균에 의한 부등식 제약조건을 두어 하강부의 진동을 제거하였다. 또한 Diskin이 지적한대로 강우 행렬의 구성을 개선하여 행렬의 차원을 줄였다. LP접근법은 대표값을 나타내는 우월성에도 불구하고 기저유출과 손실우량 분리의 정도에 매우 민감하였다. 유효우량 및 직접 유출량 분리를 위해 몇가지 방법을 적용하였으나 뚜렷이 우월한 방법은 없었다. 이것은 유역과 강우의 특성을 고려하여 판단할 문제였다. 본 연구의 앨고리즘을 낙동강 지류 위천에 적용하여 대표단휘도를 유도하였다. 기존의 IHP 성과와 비교할 때, 최적화된 대표단위 유량도의 첨두유량은 상대적으로 작고, 발생시간은 빨라졌으며, 하강부의 진동은 이동 평균법의 제약 조건에 의하여 성공적으로 소거할 수 있었다.

This paper presents an algorithm to derive the representative unit hydrograph for the real environment of a watershed. For a given watershed, the conventional methods give several different unit hydrographs by storm events. In this study the LP model is somewhat modified based on the previous study by Mays et also as follows: the objective function is designed to minimize the sum of weighted residuals. An additional constraint of moving average is added to prevent the unit hydrograph from the occurence of oscillation which was not active in Mays's paper. Configuration of rainfall matrix was improved to reduce its dimension in accordance with Diskin's review point. In spite of the superiority of LP approach in terms of representativeness, all the methods were very sensitive to the validity of baseflow separation and rainfall-loss. Several methods of the separations for rainfall excesses and direct runoffs were applied and no preferred methods were identified. This is the matter of judgement considering catchment and rainfall characteristics. This algorithm was applied to a real watershed of the Wi stream in the Nak-dong river. Compared with the IHP results by conventional methods, this optimized representative unit hydrograph demonstrated relatively smaller and shorter values in terms of the peak discharge and the basin lag respectively, and the oscillation of its falling limb successfully eliminated owing to the additional constraints of moving averages.

본 논문은 선형계획모형을 이용하여 H 아리수 정수 센터의 최적 취수량 결정 방법을 연구 하였다. 현재 H 아리수 센터에서는 관리자의 경험과 숙련도에 의지하여 취수량을 결정하고 있다. 그런데 매시 변하는 수요를 만족 시키면서 시간대별로 요금이 서로 다른 전력의 사용을 최소화 하는 취수량 결정은 근무자들의 경험과 숙련도를 넘어서는 간단한 문제가 아니다. 따라서 수리적 기법 중 하나인 선형계획모형을 이용해 취수량을 결정하고, 비용 절감을 시도하였다. 본 연구에서 제안한 선형계획 모형은 수요예측치를 기본 입력자료로 사용하고 있는데 예측오차가 발생할 경우 정수지 높이 제한을 위반하는 경우가 발생한다. 이를 해결하기 위해서는 정확한 수요예측이 선행되어야 한다. 그러나 아무리 좋은 예측 기법을 사용하더라도 실수요와 오차는 있게 마련이고 이는 여전히 높이 제한의 제약을 만족 시키지 못하는 결과를 불러일으킨다. 따라서 예측오차를 수용 할 수 있는 안전 마진 상수를 이용한 대안을 제안하였다. 본 연구에서 제안한 선형 계획 모형을 통한 취수량 결정은 수위 모니터링을 위해 항시 작업자가 근무 할 필요가 없기 때문에 인건비 면에서도 많은 절약이 예측되어 총 비용 감축은 훨씬 더 많으리라 기대된다.

Currently, the H purification plant determines the hourly water intake amount based on operator experience and skill. Therefore, inevitably, there are deviations among operators. While meeting time-varying demand and maintaining the proper water level in the clean water reservoir, the methodology for minimizing electricity cost, when dealing with different electricity rate time zones, is a very complicated problem, which is beyond an operator's capability. To solve this problem, a linear programming (LP) model is proposed, which can determine the optimal hourly water intake amount for minimizing the daily electricity cost. It is shown that an inaccurate estimate for the hourly water usage in the demand areas causes the water level constraint to be violated, which is the weak point of the proposed LP method. However, several examples with real-field data show that we can practically and safely solve this problem with safety margins. It is also shown that the safety margin method still works effectively whether the estimate is accurate or not. The operators need not attend the site at all times under the proposed LP method, and we can additionally expect reductions in labor costs.

Oil, hailed as modern industrial blood, is of greater significance to a state, and is closely related to people's lives. Shadow price of the oil industry is a key evaluation parameter for the business of an economy. In this paper, the application of input-output method and linear programming theory has been sought to establish an optimization model for the oil industry and the shadow price of the oil industry has been calculated according to the 2007 China input-output table. The analysis concludes that among the agriculture, the industry, and the tertiary industry, the prices of oil industry products bear maximum influence on the prices of agricultural products.

The purpose of this research was to make optimal design on capacity and number of multi-objective rainwater detention system that can satisfy irrigation and dimension of flood prevention as well as acquiring water source such as fire water, landscape water, and water for living in the medium and small scale basin where flood occurs frequently during focused raining due to the increase of impermeability layer. The methodology executed in this research was designed so that the construction fee and maintenance/management fee consumed in the rainwater detention system become minimized while various benefits including water and sewage cost, dam construction fee reduction, and flood damage cost reduction fee can be maximized. When considering the installation of rainwater detention system in the already developed cities or new cities, more effective design can be possible when using the same method.

With the growing popularity of cloud computing, more and more data owners are willing to outsource their data to the cloud. However, private data should be encrypted before outsourcing for security requirements, which obsoletes data utilization like content-based image retrieval. In this paper, we propose a secure similarity image search scheme, which allows data owners to outsource their encrypted image database to the cloud server without revealing the real content of images. The proposed scheme supports both global and local feature based image retrieval under various distance metrics, such as earth mover's distance. Firstly, the data owner extracts either global features or local features from images to represent the images. Then, these features are used to generate a searchable index. Finally, both image database and searchable index are encrypted before outsourcing to the cloud server. When a query image coming, the data user extracts feature from the query image and generates the search trapdoor. The trapdoor is then sent to the cloud server and used to compare the similarity with the searchable index. Extensive experiments are conducted to show the efficiency and applicability of our proposed similarity image search system.

In this paper, an energy efficient temperature control algorithm for peak power reduction in cooling systems of a large glass-covered building is proposed using control horizon method. A control horizon switching method and linear programming algorithm is used for optimal control, and a time-of-use (TOU) electricity rate is included to calculate the energy costs. Simulation results show that the reductions of energy cost and peak power can be obtained using proposed algorithms.

Distance function introduced by Shephard (1953) can be used to describe multi-inputs multi-outputs production technologies without price information. Estimated distance functions have been used for analyzing the economies of scale, the substitutability of inputs and outputs, the shadow prices of inputs and outputs, the tehcnical and allocative efficiencies of production organizations. Distance functions can be estimated using several techniques which include corrected ordinary least squares (COLS), stochastic frontier analysis (SFA), linear programming model (LPM), and quadratic programming model (QPM). In this paper we compared the merits and demerits of the four distance function estimation methods from a theoretical standpoint. Also we applied the estimation methods to the real data set used in some previous studies and we observed a guideline which allow researchers to select an appropriate distance function estimation method.

How to schedule multiple sensing units of a sensor to cover multiple targets becomes a new challenging problem. This problem is formulated as an integer linear programming problem for maximizing the network lifetime. We propose a novel energy-efficient target coverage algorithm to solve this problem based on clustering architecture. First of all, the network probability model is established and the subordinate relation between sensor nodes and the target nodes is presented. Secondly, a series of probability is computed and the related theorems and reasoning are also proven. Thirdly, effective coverage for the monitoring region is achieved through scheduling mechanism of nodes themselves, thus the purpose of increasing network lifetime can be realized. Finally, experimental results show that the proposed algorithm could achieve complete coverage for networks of different scale, and increase the network lifetime. It possesses the good quality of effectiveness and stability.

Based on data mining of outliers of time series, current studies have developed many methods, but there exist certain disadvantages for each method. This paper developed the method of mining outliers of time series based on linear programming model, verified high efficiency through an actual case and make up for the shortcoming of other methods.

In recent year, multi-layered semiconductor package is one of the most important technologies to enhance its performance. To bond between each layer of multi-chip package, die-bonding film is known as an effective material. We had developed a novel low-modulus die-bonding adhesive film. Properties of the films are widely changed by the ratio of epoxy resin and acrylic polymer contents. To satisfy the target properties, the influence of various parameters on material properties was examined. However, it is not easy for researchers to find out the formulation which satisfy the targets. To solve the problem, this paper proposes the weak conditioned combinatorial linear programming method (WCCLP). By defining solution area as a function of combination index, the optimum formulations are acquired. This optimization can be done by newly developed user-friendly software. The software is applicable not only to semiconductor related materials but also to any such formulation as paint, medicine and food.