• 전기학회논문지
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• 제60권9호
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• pp.1748-1753
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• 2011

In this paper, we consider the stability of linear systems with an interval time-varying delay. It is known that the adoption of decomposition of delay improves the stability result. For the interval time-delay case, they applied it to the interval of time-delay and got less conservative results. Our basic idea is to apply the general decomposition to the low limit of delay as well as interval of time-delay. Based on this idea, by using the modified Lyapunov-Krasovskii functional and newly derived Lemma, we present a less conservative stability criterion expressed as in the form of linear matrix inequality(LMI). Finally, we show, by well-known two examples, that our result is less conservative than the recent results.

• 산업기술연구
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• 제21권B호
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• pp.85-89
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• 2001

In this paper, we analyze a time-based update method in location management and calculate the optimal time-interval. The probability that an MT is j rings away from the center cell is obtained by computer programming. And using these values, an exact analysis is made for the time-based location management cost. From the result, when the time-based method is applied to location update, we can get the optimal time-interval which minimizes the location management cost.

• 한국항행학회논문지
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• 제18권5호
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• pp.501-507
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• 2014

음이 아닌 입력에 대하여 음이 아닌 초기상태에서 출발한 모든 상태변수 값들이 시간에 대하여 항상 음이 아닌 값을 유지하는 시스템은 양의 시스템으로 정의된다. 본 논문에서는 상태변수에 시변 지연시간이 있는 양의 시변 선형 이산 구간 시스템의 안정조건을 새롭게 제안한다. 시변 지연시간은 최소와 최대 지연시간 범위에서 변하는 것으로 고려된다. 제안된 안정조건은 리아프노프 방정식의 상한 해 한계를 이용하여 유도되며, 매우 간단한 부등식의 형태로 표현된다. 수치예제를 통하여 새로운 안정조건들이 안정성 판단에 간단하고 효과적으로 적용될 수 있음을 확인한다.

• Journal of Information Processing Systems
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• 제16권6호
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• pp.1447-1458
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• 2020

This paper describes a structured overlay network scheme based on multiple different time intervals. Many types of data (e.g., sensor data) can be requested at specific time intervals that depend on the user and the system. These queries are referred to as "interval queries." A method for constructing an overlay network that efficiently processes interval queries based on multiple different time intervals is proposed herein. The proposed method assumes a ring topology and assigns nodes to a keyspace based on one-dimensional time information. To reduce the number of forwarded messages for queries, each node constructs shortcut links for each interval that users tend to request. This study confirmed that the proposed method reduces the number of messages needed to process interval queries. The contributions of this study include the clarification of interval queries with specific time intervals; establishment of a structured overlay network scheme based on multiple different time intervals; and experimental verification of the scheme in terms of communication load, delay, and maintenance cost.

• Communications for Statistical Applications and Methods
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• 제23권4호
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• pp.335-341
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• 2016

Interval censored failure time data often occurs in an observational study where a subject is followed periodically. Instead of observing an exact failure time, two inspection times that include it are made available. Several methods have been suggested to analyze interval censored failure time data (Sun, 2006). In this article, we are concerned with a binary time-varying covariate whose changing time is interval censored. A modified estimating equation is proposed by extending the approach suggested in the presence of a missing covariate. Based on simulation results, the proposed method shows a better performance than other simple imputation methods. ACTG 181 dataset were analyzed as a real example.

• 한국경영과학회지
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• 제14권2호
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• pp.105-114
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• 1989

The actual working time of jobs, in general, is different to the standard time of jobs. In this paper, in order to analyze the actual working time of each job in production, we use the total production amount and the encessary total working time. The method which analyzes the actual working time is as follows. In this paper, we propose the interval regression analysis for obtaining an interval linear regression model with constraint conditions with respect to interval parameters. The merits of this method are the following.1) it is easy to obtain an interval linear model by solving a LP problem to which the formulation of proposed regression analysis is reduced, 2) it is easy to add constraint conditions about interval parameters, which are a sort of expert knowledge. As an application, within a case which has given certain data, the actual working time of jobs and the number of workers in a future plan are estimated through the real data obtianed from the operation of processing line in a heavy industry company. It results from the proposed method that the actual working time and the number of workers can be estimated as intervals by the interval regression model.

• 한국항행학회논문지
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• 제20권5호
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• pp.475-481
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• 2016

본 논문에서는 상태변수에 시변 지연시간이 있는 선형 이산 구간 시변 시스템의 안정조건을 새롭게 제안한다. 고려한 시스템은 지연 없는 상태변수에 대한 시스템 행렬과 지연 상태변수에 대한 시스템 행렬이 시변 구간 행렬로 표현되며, 지연시간도 구간에 대하여 시변인 특성을 갖는다. 제안된 안정조건은 리아프노프 안정 이론을 이용하여 유도되며, 매우 간단한 부등식의 형태로 표현된다. 본 논문에서는 기존의 시불변 구간 행렬의 안정성 문제를 시변 구간 행렬의 안정성 문제로 확장하고, 기존에 발표된 결과를 포함하는 강력한 안정조건이 유도된다. 이 안정조건의 유도과정에서는 복잡한 선형행렬부등식 혹은 리아프노프 방정식의 상한 해 한계를 구하지 않아도 된다. 또한, 기존의 결과들과의 비교를 통하여 제안된 안정조건이 많은 기존 안정 조건들을 포함할 수 있음을 보인다. 기존 수치예제를 일반적인 형태로 확장하였고 이에 대하여 새로운 안정조건의 확장성과 효용성을 확인한다.

• 한국항행학회논문지
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• 제19권6호
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• pp.574-580
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• 2015

본 논문에서는 상태변수에 시변 지연시간이 있는 선형 이산 구간 시스템의 안정조건을 고려한다. 고려한 시스템은 시스템 행렬과 지연 상태변수에 대한 시스템 행렬이 구간 행렬로 표현되며, 지연시간도 구간에 대하여 시변인 특성을 갖는다. 제안된 안정조건은 리아프노프 안정 이론에 의하여 유도되며 매우 간단한 부등식의 형태로 표현된다. 기존의 시불변 구간행렬의 안정성 문제를 시변 지연 시간을 갖는 시스템으로 확장한 것이다. 더불어, 새로운 안정조건은 시불변 경우에 대하여 연구된 기존 결과를 포함할 수 있으며, 구간 시변 지연 시간과 시스템의 안정성과의 연관관계를 나타내는 것이다. 제안된 조건은 구간시스템에 대한 교란 변수의 크기를 구하는 문제에도 응용될 수 있다. 수치예제를 통하여 새로운 안정조건의 효용성을 확인할 수 있으며, 기존에 발표된 결과들과의 비교도 이루어진다.

• 한국안전학회지
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• 제7권3호
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• pp.60-65
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• 1992

As many industrial workers have been involved with computer terminal tasks, for example, monitor ing, inspection, or computer da4a entry etc., concerns for difficulty evaluation of computer terminal tasks are Increased. This study provides that eyeblink can be used as a means of difficulty evaluation of a computer terminal lask. Four subjects without color blindness are asked to perform the monitoring task of the binary choice type under five levels of task difficulty. In each task, eyeblink rates and eyeblink interval times were measured from the subjects. The results show that the eyeblink rate does decrease with an Increase in task difficulty. In addition, it was found that both eyeblink interval time and eyeblink Interval time variation increased with an increase in task difficulty. It was concluded that the change of eyeblink rate, eyeblink interval time and eyeblink interval time and eyeblink interval time variation could be regarded as a generalized response to the imposition of task difficulty.

• International journal of advanced smart convergence
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• 제4권2호
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• pp.46-53
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• 2015

This paper suggests a method of real time confidence interval estimation to detect abnormal states of sensor data. For real time confidence interval estimation, the mean square errors of the exponential smoothing method and moving average method, two of the time series analysis method, were compared, and the moving average method with less errors was applied. When the sensor data passes the bounds of the confidence interval estimation, the administrator is notified through alarms. As the suggested method is for real time anomaly detection in a ship, an Android terminal was adopted for better communication between the wireless sensor network and users. For safe navigation, an administrator can make decisions promptly and accurately upon emergency situation in a ship by referring to the anomaly detection information through real time confidence interval estimation.