• 한국멀티미디어학회논문지
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• 제10권5호
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• pp.583-593
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• 2007

본 논문에서는 플래시 메모리 기반의 가상 메모리 시스템에서 페이지 부재를 처리하는 과정에 있어서 플래시 메모리에 대한 삭제연산을 줄여 시스템에서의 전력 소모를 줄일 수 있고 플래시 메모리를 균등하게 사용함으로써 플래시 메모리의 마모도 평준화 정도를 좋게 할 수 있는 CFLRU/C, CFLRU/E, DL-CFLRU/E 페이지 교체 알고리즘을 연구하였다. 제안한 기법은 메인 메모리의 페이지를 클린 페이지와 더티 페이지로 구분하고 가장 오랫동안 사용되지 않았던 페이지들 중에서 클린 페이지를 빅팀으로 선택한다. 이때, 클린 페이지가 없다면 CFLRU/C 기법은 정해진 윈도우 내에서 참조 횟수가 가장 적은 더티 페이지를 빅팀으로 선택하고, CFLRU/E 기법은 페이지가 속한 블록의 삭제 연산 횟수가 적은 더티 페이지를 빅팀으로 선택한다. DL-CFLRU/E 기법은 클린 페이지 리스트와 더티 페이지 리스트를 따로 관리하며 페이지 부재가 발생할 때 우선 클린 페이지 리스트에서 클린 페이지를 선택하며, 클린 페이지 리스트가 빈 경우, 더티 페이지 리스트에서 블록 삭제 연산 횟수가 적은 페이지를 선택한다. 본 논문에서는 시뮬레이션을 통해서 제안한 기법이 기존 기법들(LRU, CFLRU)보다 플래시 메모리의 삭제 연산을 줄일 수 있었고, 마모도 평준화 정도를 향상시킬 수 있음을 보였다.

• 산업공학
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• 제10권1호
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• pp.223-235
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• 1997

The process of determining the optimal tool path in PCB(printed circuit board) drilling operations is identical with that of solving a TSP(traveling salesman problem). However, the optimal solution will be ruined when a drill bit needs tracking back in its tool paths. The back tracking occurrences shorten a life of the main spindle and result in inaccurate mechanical movements. In this study, the performances of four heuristics(Nearest Neighbor, Convex Hull, Greatest Angle and Most Eccentric Ellipse) are evaluated to obtain feasible tool paths along with less number of back trackings for a large number of holes(more than 2000holes/bit) and to generate corresponding NC codes for a given CNC drill. Also, the operations of these algorithms are visualized to show a user the graphic image of tool visitation with PCB holes on a computer screen.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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• pp.76-78
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• 1996

When data is classified and each class has weight, the mean of data is a weighted average. When the class values and weights are trapezoidal fuzzy numbers, we can prove the weghted average is a fuzzy number though not trapezoidal. Its 4 corner points are obtained.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1990년도 춘계공동학술대회논문집; 한국과학기술원; 28 Apr. 1990
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• pp.163-170
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• 1990

Clean rooms are widely used in high technology industries. Currently within the microelectronics industry there is an explosive growth in the number of clean rooms. Therefore, special consideration of clean room workers is needed to the work induced stresses from contamination avoidance, clothing requirements, and confinements [1].

• 산업공학
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• 제21권3호
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• pp.262-273
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• 2008

In Korean peninsular, Air Defense with SAM(Surface-to-Air Missile) is very important, because of threatening by North Korea's theater ballistic missiles installed with nuclear or biochemistry. Effective and successful defense operation largely depends on two factors, SAM's location and the number of SAM for each target based on missile's availability in each SAM's location. However, most previous papers have handled only the former. In this paper, we developed Multi-heuristic algorithm which can handle both factors simultaneously for solving allocation problem of the batteries and missile assignment problem in each battery. To solve allocation problem, genetic algorithm is used to decide location of the batteries. To solve missile assignment problem, a heuristic algorithm is applied to determine the number of SAM for each target. If the proposed model is applied to allocation of SAM, it will improve the effectiveness of missile defense operations.

• 한국경영과학회지
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• 제17권2호
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• pp.35-43
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• 1992

In this paper fuzzy ranking method using dominance relation is suggested. This method is compared to the existing fuzzy number comparing methods. All ten methods with the suggested method are evaluated using six example based on four criteria.

• 한국국방경영분석학회지
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• 제12권2호
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• pp.1-21
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• 1986

Data Security in computer communication is becoming serious problem with developing computer network. This paper intended to design an encryption system to improve processing speed and to get higher degree of security by combining random number generation method, substitution method and Vernam's encryption method.

• 한국식생활문화학회지
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• 제15권2호
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• pp.69-78
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• 2000

The purposes of this study were to : (a) investigate overall operating conditions of university residence hall foodservice, (b) compare them by the management systems. Questionnaires were hand delivered and mailed to 73 foodservice managers. A total of 56 were usable; resulting in 76.7% response rate. The survey was conducted between October, 1998 and May, 1999. Statistical data analysis was completed using the SAS/Win 6.12 for Descriptive Analysis, $x^2-test$. Sixty-four percent of the foodservice operations were 'self-operated'; 23% were 'contracted'; and 13% were 'rented'. Eighty-three percent of operations provided 'single menu'; forty-six percent of foodservice operations with 'partially self-service'; and forty-one percent with 'complete self-service'. Forty-four percent of overall foodservice operations provided 1,000-2,000 meals per day; thirty-one percent provided less than 1,000 meals per day, and twenty-four percent provided more than 2,000 meals per day. The highest meal price was 1,950 won and the lowest was 700 won with average of 1,295 won. The mean number of employees was 12.2; the number of working hours was 59.7 hours per week.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.715-718
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• 2000

Although shared memory parallel programs are designed to be deterministic both in their final results and intermediate states, the races that occur when different processes access a common memory location in an order not guaranteed by synchronization could result in unintended non-deterministic executions of the program. So, Detecting races, particularly first data races, is important for debugging explicit shared memory parallel programs. It is possible that all data races reported by other on-the-fly algorithms would disappear once the first races were removed. To detect races parallel programs with nested loops and inter-thread coordination, it must guarantee the order of synchronization operations in an execution instance. In this paper, we propose an improved restructuring method that guarantee ordering execution instance and preserve the semantics of original program. This method requires O(np) time and (s + up) space, where n is the number of total operations, s is the number of synchronization operations and p is the number of parallelism in the execution. Also, this method makes on-the-fly detection of parallel program with nested loops and inter-thread coordination more easily in space and time complexity.

• 한국컴퓨터정보학회논문지
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• 제20권11호
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• pp.1-8
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• 2015

Flash memory has advantages in that it is fast access speed, low-power, and low-price. Therefore, they are widely used in electronics industry sectors. However, the flash memory has weak points, which are the limited number of erase operations and non-in-place update problem. To overcome the limited number of erase operations, many wear leveling techniques are studied. They use many tables storing information such as erase count of blocks, hot and cold block indicators, reference count of pages, and so on. These tables occupy some space of main memory for the wear leveling techniques. Accordingly, they are not appropriate for low-power devices limited main memory. In order to resolve it, a wear leveling technique using bit array and Bit Set Threshold (BST) for flash memory. The proposing technique reduces the used space of main memory using a bit array table, which saves the history of block erase operations. To enhance accuracy of cold block information, we use BST, which is calculated by using the number of invalid pages of the blocks in a one-to-many mode, where one bit is related to many blocks. The performance results illustrate that the proposed wear leveling technique improve life time of flash memory to about 6%, compared with previous wear leveling techniques using a bit array table in our experiment.