• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.103-110
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• 2020

In the recent seismic design code KDS 41 17 00, selection and modification procedures of ground motions which are used for nonlinear dynamic analyses were adopted. However, its practical applications are still limited due to the lack of literatures. This paper introduces case studies which used site-response analyses to select and modify ground motions for nonlinear dynamic analyses. Based on the case studies, design criterion for site-response analyses were reviewed thoroughly in the viewpoint of practical applications. It was found that design requirements related with bedrock motions are too conservative that ground motions are selected and modified in the excessive manner. It is especially true for low-rise building structures with period ranges including acceleration-sensitive regions. Even though surface motions have shown appropriate responses, such building structures have to re-select and re-modify ground motions based on pre-analysis procedures rather than post-ones according to the current seismic design code. Also, it was observed that building structures with soft soils under strong ground motions need more comprehensive investigations on soil properties and efficient analysis methods in order to perform site-response analyses. This is due to the fact that lack of reliabilities on soil properties and analysis methods could result in unstable site-responses.

• The Korean Journal of Applied Statistics
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• v.22 no.6
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• pp.1315-1329
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• 2009

The panel survey is need to have a more concern about a response due to a secession and non-response of a sample. And generally a population is not fixed and continuously changed. Thus, the rotation sample design can be used by the method replacing the panel research. This paper is the study of comparison to equal weight method, Duncan weight, Design weight method, weight share method in rotation sample design. More specifically, this paper compared variance estimators about the existing each method for the efficiency comparison, and to compare the precision using the relative efficiency gain by the Coefficient Variance(CV) after getting the design weight from the actual data.

• 한국지구물리탐사학회:학술대회논문집
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• 2011.10a
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• pp.71-72
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• 2011

• The Journal of the Acoustical Society of Korea
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• v.31 no.3
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• pp.197-204
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• 2012

In this thesis, studied the method to minimize the changes in frequency response and level due to the variation of the distance from the source to the microphone. selecting three microphones (omni directional, cardioid, super cardioid) which are being used generally, frequency responses were measured in accordance with the distance changes. Gotten the difference from the reference as the result of measurement, changed responses for each frequency range were compensated in comparison of the original human vocal source. In low frequency range, the low frequency boost caused by the proximity effect and decrease in accordance with the distance were compensated. The variation in mid-frequency range is comparatively small, however since the mid-range is the most important part of the human vocal signal, were compensated the mid-frequency range in comparison of the reference. The human vocal signal variation in high frequency range is extremely small and the high frequency is compensated close to the original source without difficulty. Understanding the microphone characteristics and compensations, this study showed that the response can be maintain among the change of the distance from the source to the microphone.

• The Journal of the Acoustical Society of Korea
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• v.32 no.6
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• pp.509-517
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• 2013

In this paper, we researched a method that makes a good acoustic-speech system using a digital signal processing technique with dynamic microphone as a transducer. Good acoustic-speech system should deliver the original sound input to electric signal without distortion. By measuring the frequency response of the microphone, adjustment factors are obtained by comparing measured data and standard frequency response of microphone for each frequency band. The final sound levels are obtained using the developed adjustment factors of frequency responses from the microphone and speaker to match the original sound levels using the digital signal processing technique. Then, we minimize the changes in the frequency response and level due to the variation of the distance from source to microphone, where the frequency responses were measured according to the distance changes.

• The Korean Journal of Applied Statistics
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• v.32 no.4
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• pp.631-642
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• 2019

Many methods have been developed to solve problems found in sample surveys involving a large number of item non-responses that cause inaccuracies in estimation. However, the non-response adjustment method used under the assumption of random non-response generates a bias in cases where the response rate is affected by the variable of interest. Chung and Shin (2017) and Min and Shin (2018) proposed a method to improve the accuracy of estimation by appropriately adjusting a bias generated when the response rate is a function of the variables of interest. In this study, we studied a case where the response rate function is linear and the error of the super population model follows normal distribution. We also examined the effect of the number of stratum population on bias adjustment. The performance of the proposed estimator was examined through simulation studies and confirmed through actual data analysis.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.57-59
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• 2007

정보보호시스템 평가수요의 예측은 예측된 평가수요를 근거로 적극적인 평가서비스를 제공하기 위하여 필요하다. 평가수요예측을 하기위하여 일반적으로 설문조사를 이용하지만 무응답 및 불성실한 응답으로 인하여 설문응답 자료만으로 평가수요를 예측하기에는 부족하다. 따라서 설문조사의 평가수요를 보정할 수 있는 모형이 필요하다. 본 논문에서는 설문조사를 통하여 예측 할 수 있는 직접적인 평가수요와 통계적 모형을 이용한 간접적 평가수요를 비교하고 설문조사의 대체 방법을 제시하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.129-133
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• 2019

Frequency resource efficiency is important in satellite communication systems. One of the causes of a waste of frequency resource is bad flatness. In the case, flatness of satellite Tx terminals would be worse by ACI and guard band. In order to overcome this problem, this paper proposes a technique for frequency response equalization in satellite Tx terminals. First of all, a general linear polynomial expression which meets least squares of representative measurement data is calculated to interpolate unmeasured data. And then flatness can be adjusted using the polynomial expression. Simulation results illustrate adjusted data have lower peak to peak and standard deviation than original data, and these show that flatness be improved.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.173-178
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• 2001

부분구조 합성법(substructuring or substructure synthesis)은 부분구조(substructure)의 주파수 응답함수(FRFs, frequency response functions)를 이용하여 합성된 전체 구조물의 동특성(dynamic behavior)을 파악하는 기술로서 이에 관한 이론은 명확하며 간단하다. 즉, 역행렬 계산과 같은 기본적인 행렬연산으로 부분구조 합성을 수행한다. 그러나, 여러 가지 요인으로 인하여 계산된 합성 결과는 실제로 결합된 전체 구조물의 동특성과는 차이를 보인다. 현실적인 이유로 고려하지 못하는 회전자유도와 실험에서 수반되는 여러 가지 측정오차는 주요한 요인이며 이에 대한 연구 또한 많이 진행되었다. 본 연구에서는 이러한 요인 중, 상대적으로 덜 중요하게 평가된 모드자름 오차(modal truncation error)의 영향을 고려한다. 단순한 구조물에 대하여 모의실험을 수행함으로써, 모드자름 오차로 인하여 완전히 잘못된 합성 결과가 나을 수 있다는 것을 보인다. 측정된 FRE를 이용하여 이러한 오차를 보정(compensation)하는 소개하고 이를 대상 구조물에 적용하여 모드자름 오차의 영향을 상당히 줄일 수 있다는 것을 보인다. 복잡한(complicated) 구조물에 대하여 모드자름 오차의 영향을 줄이기 위해서 모든 FRFs를 보정하는 것은 어려우므로 현실적인 대안을 모색한다.

• Journal of the KSME
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• v.25 no.4
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• pp.304-311
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• 1985

원자력발전소는 사고시 주변의 인구 및 환경에 미치는 영향의 심각성을 고려하여 가능한 모든 안전조치를 취하여 설계. 건설되도록 하고 있다. 특히 원자로냉각재 계통의 배관이 그러하며 고도의 안전성 및 신뢰성을 확보하기 위하여 지진에 대해서도 구조적인 건전성이 입증되어야 한다. 일반적으로 지진하중에 대한 배관계통의 내진해석에서는 층응답스펙트럼에 의한 모우드 해석 방법이 이용되고 있다. 이 때 내진해석으로 얻어진 응답의 조합에는 신중한 고려가 필요 하다. 즉 배관계통의 특성, 입력지진의 특성, 계산에 고려하는 모우드의 수등을 감안하여 적절한 응답조합이 이루어져야 한다. 본 해설에서는 여러 가지의 응답조합방법과 해석시 고려되는 모 우드의 수를 제한함으로써 발생하는 오차를 보정하기 위한 누락질량효과(missing mass effect)에 대하여 설명하고자 한다. 또 두 가지의 해석모델에 대하여 실제 내진 해석을 수행하여 그 결 과를 비교검토하기로 한다.