• 한국해양학회지:바다
• /
• 제11권4호
• /
• pp.133-144
• /
• 2006

해수 소통이 전제된 새만금호의 내부 관리수위를 유지하는 최적의 수문 운영안이 ADCIRC모형을 적용한 실험을 통해 검토되었다. 수문 완공 이후와 내부개발 이후로 사업진행을 구분하였고 평수시와 풍수시로 하천유량을 구분하여 모델링을 실시하였다. 수문 운영방안은 유입/배출이 연속적으로 1일 1회, 1일 2회 및 2일 1회 등에 대해 검토되었으나 모든 경우 하천 유입 유량에 의해 수위가 지속적으로 상승된다. 목표 관리수위 0.0m를 유지할 수 있는 현실적인 방안으로는 방조제 완공 직후에는 1일 2회의 유입/배출을 유지하면서 평수시에는 단속적으로 6일에 한번, 풍수시에는 3일에 한번 외해수의 유입을 억제시키면 최대편차 ${\pm}0.4m$ 이내에서 관리수위 유지가 가능한 것으로 분석되었다.

• 한국경영과학회:학술대회논문집
• /
• 한국경영과학회 1993년도 추계학술대회발표논문집; 서강대학교, 서울; 25 Sep. 1993
• /
• pp.118-118
• /
• 1993

We consider a discrete event dynamic system called periodic job shop, where an identical mixture of items called minimal part set(MPS) is repetitively produced in the same processing order and the primary performance measure is the cycle time. The precedence relationships among events(starts of operations) are represented by a directed graph with rocurront otructure. When each operation starts as soon as all its preceding operations complete(called earliest starting), the occurrences of events are modeled in a linear system using a special algebra called minimax algebra. By investigating the eigenvalues and the eigenvectors, we develop conditions on the directed graph for which a stable steady state or a finite eigenvector exists. We demonstrate that each finite eigenvector, characterized as a finite linear combination of a class of eigenvalue, is the minimum among all the feasible schedules and an identical schedule pattern repeats every MPS. We develop an efficient algorithm to find a schedule among such schedules that minimizes a secondary performance measure related to work-in-process inventory. As a by-product of the linear system approach, we also propose a way of characterizing stable steady states of a class of discrete event dynamic systems.

• Journal of Astronomy and Space Sciences
• /
• 제17권2호
• /
• pp.309-316
• /
• 2000

KOMPSAT-2 will carry MSC(Multi-Spectral Camera) which provides 1m resolution panchromatic and 4m resolution multi-spectral images at the altitude of 685km sun-synchronous mission orbit. The mission operation of KOMSPAT-2 is to provide the earth observation using MSC with nadir pointing. KOMPSAT-2 will also have the capability of roll/pitch tilt maneuver using reaction wheel of satellite as required. In order to protect MSC from thermal distortion as well as direct sunlight, MSC shall be operated within the constraint of sun incidence angle. It is expected that the sunlight will not violate the constraint of sun incidence angle for normal mission operations without roll/pitch maneuver. However, during roll/pitch tilt operations, optical module of MSC may be damaged by the sunlight. This study analyzed sun incidence angle of payload using KOMPSAT-2 AOCS (Attitude and Orbit Control Subsystem) Design and Performance Analysis Soft ware for KOMPSAT-2 normal mission operations.

• 한국경영과학회지
• /
• 제33권2호
• /
• pp.75-86
• /
• 2008

A remarshalling is one of the operational strategies considered importantly at a port container terminal for the fast ship operations and heighten efficiency of slacking yard. The remarshalling rearranges the containers scattered at a yard block in order to reduce the transfer time and the rehandling time of container handling equipments. This Paper deals with the rearrangement problem, which decides to where containers are transported considering time value of each operations. We propose the mixed integer programming model minimizing the weighted total operation cost. This model is a NP-hard problem. Therefore we develope the heuristic algorithm for rearrangement problem to real world adaption. We compare the heuristic algorithm with the optimum model in terms of the computation times and total cost. For the sensitivity analysis of configuration of storage and cost weight, a variety of scenarios are experimented.

• Journal of information and communication convergence engineering
• /
• 제12권1호
• /
• pp.60-65
• /
• 2014

This paper describes an efficient framework for the extraction of a brain tumor from magnetic resonance (MR) images. Before the segmentation process, a median filter is used to filter the image. Then, the morphological gradient is computed and added to the filtered image for intensity enhancement. After the enhancement process, the thresholding value is calculated using the mean and the standard deviation of the image. This thresholding value is used to binarize the image followed by the morphological operations. Moreover, the combination of these morphological operations allows to compute the local thresholding image supported by a flood-fill algorithm and a pixel replacement process to extract the tumor from the brain. Thus, this framework provides a new source of evidence in the field of segmentation that the specialist can aggregate with the segmentation results in order to soften his/her own decision.

• 한국경영과학회지
• /
• 제40권2호
• /
• pp.63-77
• /
• 2015

The territorial air that our sovereignty is being applied to is divided into several zones and areas. In order to use and manage them effectively, these zones and areas have laws, regulations and rules. The number of airspaces (MOA : Military Operation Area) and Ranges that are used in the military are limited and many airbases are being used for training. Currently the central department manages some, and the rest are independent airbases. Therefore, efficient allocation is not performed and the result occurs where airspaces and ranges are allocated unnecessarily. This is increasing the workload of staff leading to unnecessary re-work. To slove problem, this study proposed models for allocating airspaces and ranges using goal programming with multi-objective functions of minimizing the deviations of the target values.

• 정보저장시스템학회논문집
• /
• 제6권2호
• /
• pp.41-46
• /
• 2010

Recently, Flash Memory Drives are one of the best media to support portable and desktop computers' storage devices. Their features include non-volatility, low power consumption, and fast access time for read operations, which are sufficient to present flash memories as major database storage components for desktop and server computers. However, we need to improve traditional storage management schemes based on HDD(Hard Disk Drive) and RAID(Redundant Array of Independent Disks) due to the relatively slow or freezing characteristics of write operations of SSDs, as compared to fast read operations. In order to achieve this goal, we propose a new storage management scheme called Hetero-Mirroring based on traditional HDD mirroring scheme. Hetero-Mirroring-based storage management improves RAID-1 operation performance by balancing write-workloads and delaying write operations to avoid SSD freezing.

• 한국정밀공학회지
• /
• 제11권1호
• /
• pp.211-218
• /
• 1994

Grinding is considered as a very effective machining technology to attain high production rates and a good surface quality of hard and brittle components. However, the grinding operations till needs the skill and the experience of an operator because of a lack of scientific knowledge and engineering principles. This is the reason why grinding operations are not completley intergrated in CIMS(Computer Intergrated Manufacturing System. Recent develop- ment focus on expert system which deals with domain specific knowledge in order to solve this problem. Firstly, in this study, a basic strategy to develop the grinding knowledge-base for grinding is discussed. Next, the architecture of knowledge-base and management of the grinding knowledge-base(GKB) is described.

• 한국국방경영분석학회지
• /
• 제24권2호
• /
• pp.43-56
• /
• 1998

This paper focuses on the optimal replacement time of engine modules of the F16 aircraft. Generally, the optimal replacement time of those should be determined to minimize the replacement cost due to out of order and opportunistic replacement cost of operation cost of remaining period. This paper determined the optimal replacement time by using the opportunistic replacement algorithm that is developed by Forbes and Wyatt. Some real data are utilized but a few data is estimated due to limitation of data. As a result, fan module only reaches to the opportunistic replacement time. The optimal replacement time of the fan module is derived as 1740 cycles. Therefore, the optimal replacement policy of engine modules of the F16 is that fan module should be replaced whenever it is out of order under 1740 cycles and whenever core module is out of order over 1740 cycles.

• 한국정밀공학회지
• /
• 제7권3호
• /
• pp.66-74
• /
• 1990

This paper presents a knowledge-based computer aided process planning system that automatically selects machine tools, machining operations and cutting tools and determines sequences of the machining operations for prismatic parts in die manufacturing. In the proposed system, parts are described by manufacturing features and grouped into part families based on the functions. Each part is repressented by a part frame which consists of basic data and manufacturing features. Knowledge for manufacturing is acquired from the domain expert and represented by frames. A decision model for selection of machine tools, machining operations and cutting tools and for determining sequences of the machining operations are developed by employing the Mealy machine in finite automata with output. The decision procedure and the order of priority which inputs manufacturing features into the Mealy machine are represented by rule for each part family. Backward chaining is used for the proposed system. The proposed system is implemented by using TURBO-PROLOG on the IBM PC/AT. A case study for the slide core is presented to show the function of the proposed system.