• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.444-449
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• 1996

The semiconductor, which is precision product, requires many inspection processes. The surface conditions of the semiconductor chip affect on the functions of the semiconductors. The defects of the chip surface are cracks or voids. As general inspection method requires many inspection procedure, the inspection system which searches immediately and precisely the defects of the semiconductor chip surface is required. We suggest the detection algorithm for inspecting the surface defects of the semiconductor surface. The proposed algorithm first regards the semiconductor surface as random texture and point spread function, and secondly presents the character of texture by linear estimation theorem. This paper assumes that the gray level of each pixel of an image is estimated from a weighted sum of gray levels of its neighbor pixels by linear estimation theorem. The weight coefficients are determined so that the mean square error is minimized. The obtained estimation window(two-dimensional estimation window) characterizes the surface texture of semiconductor and is used to discriminate the defects of semiconductor surface.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1999년도 춘계학술대회 논문집
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• pp.47-52
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• 1999

In this paper we propose new approximate method for the performance analysis of closed-loop production system with unreliable machines and random processing times. The approximate method decomposes the production system consisting of K machines into a set of K subsystems, each subsystem consisting of two machines separated by a finite buffer. Then, each subsystem is analyzed by analyzing method n isolation. The population constraint of the closed-loop production system is taken into account by prescribing that the sum of average buffer level in the subsystems is equal to the number of customers in the closed-loop production system,. We establish a set of equations that characterizes unknown parameters of the servers in the subsystems. An iterative procedure is then used to determine the unknown parameters. Experimental results show that these methods provide a good estimation of the throughput.

• 한국음향학회지
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• 제3권2호
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• pp.59-68
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• 1984

어군의 밀도를 음파로 추정할 때 어군의 총후방 산란 단면적이 어류개체의 후방 산란 단면적을 random phase로 합한 것과 같다는 가정에 대하여 실험적 검증을 시도하였다. 어체의 길이 대 음파의 파장비가 23일 때 두 마리와 세 마리의 숭어에 대하여 실시한 실험에서 전 산란각에 대한 편균이 random phase로 합할 때 보다 -1.7dB와 +1dB씩 편차를 보였다. 그러나 전체적으로는 in phase와 out phase sum 사이에서 변화함을 보였고, 최대오차는 in phase로 합해질 때로서 실제의 어군밀도 n에 비 해 최고 n\sup 2\에 이르기까지 추정 가능함을 실험결과는 보여주고 있다. 더욱이 이러한 결과는 어체간 의 간격변화에는 거의 무관하였으므로 소나무 빔폭이나 어군의 분포에 상관없이 빔폭 사이에 있는 어군 의 마리수에만 퐁후방 산란 단면적이 관계된다는 결론을 얻을 수 있었다.

• 대한산업공학회지
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• 제25권2호
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• pp.240-253
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• 1999

In this paper we propose new approximate methods for the performance analysis of closed-loop production systems with unreliable machines and random processing times. Each approximate method decomposes the production system consisting of K machines into a set of K subsystems, each subsystem consisting of two machines separated by a finite buffer. Then, each subsystem is analyzed by three different analyzing methods in isolation. The population constraint of the closed-loop production system is taken into account by prescribing that the sum of average buffer levels in the subsystems is equal to the number of customers in the closed-loop production system. We establish a set of equations that characterize unknown parameters of the servers in the subsystems. An iterative procedure is then used to determine the unknown parameters. Experimental results show that these methods provide a good estimation of the throughput.

• 한국소음진동공학회논문집
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• 제12권7호
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• pp.520-526
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• 2002

Identification of noose sources, their locations and strengths, has been taken great attention. The methods that can identify noise sources normally assume that noise sources are located in a free field. However, the sound in a reverberant field consists of that coming directly from the source plus sound reflected or scattered by the walls or objects in the field. In contrast to the exterior sound field. reflections are added to sound field. Therefore, we haute to consider the reverberation effect on the source identification method. The main objective of this paper is to identify noise source in the reverberant field. At fist, we try to identify noise sources in a rigid wall emc;psire using the beamforming method. In many cases of practical interest, the wall has admittance so that random reflections occur in an enclosure. In this paper, we assumed the complex reverberant field in the enclosure to be the sum of plane caves with random Incidence and magnitude. Then we try to explain effects of reverberant field at interior source identification.

• Communications for Statistical Applications and Methods
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• 제29권5호
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• pp.561-589
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• 2022

When multiple classifications and regression trees are combined, tree-based ensemble models, such as random forest (RF) and Bayesian additive regression trees (BART), are produced. We compare the model structures and performances of various ensemble models for regression settings in this study. RF learns bootstrapped samples and selects a splitting variable from predictors gathered at each node. The BART model is specified as the sum of trees and is calculated using the Bayesian backfitting algorithm. Throughout the extensive simulation studies, the strengths and drawbacks of the two methods in the presence of missing data, high-dimensional data, or highly correlated data are investigated. In the presence of missing data, BART performs well in general, whereas RF provides adequate coverage. The BART outperforms in high dimensional, highly correlated data. However, in all of the scenarios considered, the RF has a shorter computation time. The performance of the two methods is also compared using two real data sets that represent the aforementioned situations, and the same conclusion is reached.

• 대한수학회보
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• 제59권4호
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• pp.879-895
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• 2022

This paper establishes the Baum-Katz type theorem and the Marcinkiewicz-Zymund type strong law of large numbers for sequences of coordinatewise negatively associated and identically distributed random vectors {X, X_n, n ≥ 1} taking values in a Hilbert space H with general normalizing constants $b_n=n^{\alpha}{\tilde{L}}(n^{\alpha})$, where ${\tilde{L}}({\cdot})$ is the de Bruijn conjugate of a slowly varying function L(·). The main result extends and unifies many results in the literature. The sharpness of the result is illustrated by two examples.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.101-104
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• 2000

In this paper, we analyze the propagation modeling methods to evaluate the IMT-2000 satellite RTT (Radio Transmission Technology). To generate Rayleigh random numbers having Jake's Doppler power density spectrum, the Rice's sum of sinusoids methods are used and their statistical characteristics are compared with each other.

• Journal of the Korean Statistical Society
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• 제28권4호
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• pp.523-533
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• 1999

We consider the M/G/1 queueing model with D-policy. The server is turned off at the end of each busy period and is activated again only when the sum of the service times of all waiting customers exceeds a fixed value D. We obtain the distribution of unfinished work and show that the unfinished work decomposes into two random variables, one of which is the unfinished work of ordinary M/G/1 queue. We also derive the distribution of queue waiting time.

• 충청수학회지
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• 제26권3호
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• pp.491-499
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• 2013

In this paper, we prove the weak law of large numbers for weighted sums of noncommutative random variables in noncommutative Lorentz space under weaker conditions than the conditions in [7].