• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.923-929
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• 2002

We discuss scheduling analysis for a discrete event system with time windows of which firing or holding time delays are subject to random variation within some finite range. To do this, we propose a modified p-lime Petri net, named p+-time Petri net. We develop a condition for which a synchronized transition does not have a dead token, that is, the firing epochs do not violate the time window constraints. We propose a method of computing the feasible range of the token sojourn time at each place based on a time difference graph. We also discuss an application for analyzing wafer residency times within the process chambers for a dual-armed cluster tool for chemical vapor deposition.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.116-122
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• 2016

Recently, the production cycle in manufacturing process has been getting shorter and different types of product have been produced in the same process line. In this case, the control chart using coefficient of variation would be applicable to the process. The theory that random variables are located in the three times distance of the deviation from mean value is applicable to the control chart that monitor the process in the manufacturing line, when the data of process are changed by the type of normal distribution. It is possible to apply to the control chart of coefficient of variation too. ${\bar{x}}$, s estimates that taken in the coefficient of variation have just used all of the data, but the upper control limit, center line and lower control limit have been settled by the effect of abnormal values, so this control chart could be in trouble of detection ability of the assignable value. The purpose of this study was to present the robust control chart than coefficient of variation control chart in the normal process. To perform this research, the location parameter, ${\bar{x_{\alpha}}}$, $s_{\alpha}$ were used. The robust control chart was named Tim-CV control chart. The result of simulation were summarized as follows; First, P values, the probability to get away from control limit, in Trim-CV control chart were larger than CV control chart in the normal process. Second, ARL values, average run length, in Trim-CV control chart were smaller than CV control chart in the normal process. Particularly, the difference of performance of two control charts was so sure when the change of the process was getting to bigger. Therefore, the Trim-CV control chart proposed in this paper would be more efficient tool than CV control chart in small quantity batch production.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.1
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• pp.76-80
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• 2010

It is floating to security of information and the early assignment that it is important it processes and to transmit in inundations of information that I changed suddenly. I used the encryption/decryption process that applied simple substitution and mathematical calculation algorithm at theory and encryption transmission steps protective early information. Hardware and financial loss are using spurious random number to be satisfied with the random number anger that isn't real random number to size so much perfect information protection using One-time pad for applying this. I was transformed into serial test under a test to prove spurious random number anger, and it is into random number anger stronger, and the transformation serial test that proposes is proving it in algorithm speed and efficiency planes.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.3
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• pp.363-369
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• 2017

Phase-change random access memory (PRAM) has been emerged as a potential memory due to its excellent scalability, non-volatility, and random accessibility. But, as the cell current is reducing due to cell size scaling, the read-sensing window margin is also decreasing due to increased variation of cell performance distribution, resulting in a substantial loss of yield. To cope with this problem, a novel adaptive read-sensing reference current generation scheme is proposed, whose trimming range and resolution are adaptively controlled depending on process conditions. Performance evaluation in a 58-nm CMOS process indicated that the proposed read-sensing reference current scheme allowed the integral nonlinearity (INL) to be improved from 10.3 LSB to 2.14 LSB (79% reduction), and the differential nonlinearity (DNL) from 2.29 LSB to 0.94 LSB (59% reduction).

• Computers and Concrete
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• v.12 no.1
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• pp.91-107
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• 2013

Corrosion of RC bridge decks eventually leads to delamination, severe cracking and spalling of the concrete cover. This is a prevalent deterioration mechanism and demands for the most costly repair interventions during the service life of bridges worldwide. On the other hand, decisions for repairs are usually made whenever the extent of a limit crack width, reported in routine visual inspections, exceeds an acceptable threshold level. In this paper, while random fields are applied to account for spatial variation of governing parameters of the corrosion process, an analytical model is used to simulate the corrosion induced crack width. However when dealing with random fields, the Monte Carlo simulation is apparently an inefficient and time consuming method, hence the utility of neural networks as a surrogate in simulation is investigated and found very promising. The proposed method can be regarded as an invaluable tool in decision making concerning maintenance of bridges.

• Structural Engineering and Mechanics
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• v.70 no.1
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• pp.81-96
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• 2019

In this paper, a hybrid uncertain model is applied to system reliability based design optimization (RBDO) of trusses. All random variables are described by random distributions but some key distribution parameters of them which lack information are defined by variation intervals. For system RBDO of trusses, the first order reliability method, as well as monotonicity analysis and the branch and bound method, are utilized to determine the system failure probability; and Improved (${\mu}+{\lambda}$) constrained differential evolution (ICDE) is employed for the optimization process. System reliability assessment of several numerical examples and system RBDO of different truss structures are proposed to verify our results. Moreover, the effect of different classes of interval distribution parameters on the optimum weight of the structure and the reliability index are also investigated. The results indicate that the weight of the structure is increased by increasing the uncertainty level. Moreover, it is shown that for a certain random variable, the optimum weight is more increased by the translation interval parameters than the rotation ones.

• Journal of IKEEE
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• v.25 no.2
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• pp.309-314
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• 2021

The proposed preamplifier for the static random access memory reduces the time required for the sense amplifier enable during the read operation by 55%, which leads to a significant speed up the total spped. This is attirbuted to the novel circuit techqniue that cancels out the transistor mismatch which is induced by the process variation. In addition, a selective enable circuit for preamplifier circuit is proposed, so the proposed preamplifier is enabled only when it is required. Accordingly the energy overhead is limited below 4.45%.

• JSTS:Journal of Semiconductor Technology and Science
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• v.9 no.1
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• pp.37-50
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• 2009

Evaluation results about area scaling capabilities of various SRAM margin-assist techniques for random $V_T$ variability issues are described. Various efforts to address these issues by not only the cell topology changes from 6T to 8T and 10T but also incorporating multiple voltage-supply for the cell terminal biasing and timing sequence controls of read and write are comprehensively compared in light of an impact on the required area overhead for each design solution given by ever increasing $V_T$ variation (${\sigma}_{VT}$). Two different scenarios which hinge upon the EOT (Effective Oxide Thickness) scaling trend of being pessimistic and optimistic, are assumed to compare the area scaling trends among various SRAM solutions for 32 nm process node and beyond. As a result, it has been shown that 6T SRAM will be allowed long reign even in 15 nm node if ${\sigma}_{VT}$ can be suppressed to < 70 mV thanks to EOT scaling for LSTP (Low Standby Power) process.

• International Journal of Quality Innovation
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• v.4 no.1
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• pp.46-53
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• 2003

Under the strong leadership of Chinese Government to the anti-SARS struggle, the situation has been successfully controlled. Since May 1 of 2003, the Ministry of Health of China published daily the number of newly increased SARS patient of Beijing, the authors analyzed these data using $X_cs$$-R_scs$ cause-selecting control charts of Statistical Diagnosis(SPD) Theory. Data about number of newly increased SARS patient consists of two kinds of variation: random variation and tendency variation of SARS epidemic. It is concluded that SARS epidemic of Beijing was already controlled since May 9 of 2003.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.2
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• pp.184-188
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• 2014

There is a trade-off between read stability and writability under a full-/half-select condition in static random access memory (SRAM). Another trade-off in the minimum operating voltage between the read and write operation also exists. A new peripheral circuit for SRAM arrays, called a variation sensor, is demonstrated here to balance the read/write margins (i.e., to optimize the read/write trade-off) as well as to lower the minimum operation voltage for both read and write operations. A test chip is fabricated using an industrial 45-nm bulk complementary metal oxide semiconductor (CMOS) process to demonstrate the operation of the variation sensor. With the variation sensor, the word-line voltage is optimized to minimize the trade-off between read stability and writability ($V_{WL,OPT}=1.055V$) as well as to lower the minimum operating voltage for the read and write operations simultaneously ($V_{MIN,READ}=0.58V$, $V_{MIN,WRITE}=0.82V$ for supply voltage $(V_{DD})=1.1V$).