• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.2
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• pp.82-89
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• 2006

The flutter/vibroacoustic characteristics can be acquired by conducting flight tests with various conditions for a long period of test. Accordingly it is indispensable to build a specially designed database system to efficiently accumulate the enormous data obtained from flight tests. Hence, T-50 Flight Test Database System(FTDS) based on MS-Access is developed to handle the flutter/vibroacoustic environment data obtained from flight tests. The developed system is structured with the items related to aircraft flight test, the tables composed of the relevant items and a relational database logically connecting the tables. The T-50 FTDS is implemented with data searching GUI(Graphic User Interface) programed with Visual Basic and Structured Query Language to make intuitive searches over the stored data. The developed system has been used for accumulating the flutter/vibroacoustic data and verifying vibroacoustic Specifications.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.812-816
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• 2014

Recently, there is an increasing interest on railway noise and vibration. Accordingly, the importance of technology that can assess the vibration and structural noise caused due to the railway operation is increasing. Additionally, the need to construct a railway noise and vibration database which is a basic data for a reliable railway noise and vibration assessment as well is increasing. However, the problem is that the currently constructed database fails to include the factors influencing the occurrence of noise and vibration sufficiently. Therefore, In this paper, design a railway noise and vibration database that includes those factors sufficiently and which enables the continuous data management and accumulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.882-883
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• 2013

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.785-786
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• 2012

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.855-861
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• 2000

선박의 설계초기 단계에서 주요 진동특성인 주선체 및 상부구조의 고유 진동수와 고유 진동형을 구하게 위해서는 현재까지 주로 경험식에 의존하게 된다. 이들 경험식들은 만들어진 시기가 최소 20년 이상 씩 됨에 따라 이중선체 유조선, IMO의 visibility 규정의 강화에 따른 상부조 높이의 증가, 콘테이너 선의 초 대형화 경향과 같이 최근의 선박 변화가 제대로 반영되어 있지 못하기 때문에 최근 선박의 진동특성을 추정하는 데는 많은 오차를 유발할 수 있다. 따라서 본 연구에서는 실적선들의 진동해석 및 계측 결과들을 정리하여 데이터베이스화하고 이들 자료들을 이용하여 회귀분석 방법에 의해 통계해석을 수행하므로써 설계 초기단계에서 선박의 진동 특성을 정도 높게 추정하는 방법을 개발하고 주기관 및 프로펠러 날개 수 선정에도 정확도를 기할 수 있도록 하였다. 또한 본 방법을 바탕으로 windows환경의 전산프로그램으로 개발하여 사용자의 편의성을 크게 도모하였다. 본 방법의 타당성과 정도를 확인하기 위해 일련의 수치계산을 수행하여 계측치와의 부합성이 매우 양호함을 보였다.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.4
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• pp.153-162
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• 2019

Recently, it is necessary to develop a technology for quantitatively evaluating railway vibration to prevent civil complaints about orbital structures caused by railway noise and normal operation of ultra-precise equipment of orbital industrial complexes. The existing analytical method requires a very complicated dynamic response model, and it is difficult to secure the reliability of the result due to the inaccuracy of the demand model. Therefore, in this paper, we propose a railway vibration evaluation algorithm and system that deduce the vibration value generated from railway operation by using Linear Regression and Gradient Descent technique based on actual measurement railway vibration database that classifies factors affecting railway vibration. The prediction results obtained by the proposed algorithm show higher efficiency and accuracy than the existing analytical methods.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.715-716
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• 2013

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.33-36
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• 2014

철도로 인한 소음 문제는 최근 국민의 정온한 환경에 대한 권리의식 증대와 삶의 질에 대한 높은 관심으로 철도 소음에 대한 민원이 급증하여 지역 갈등을 초래하고 막대한 사회적 비용 부담으로 철도 산업을 저해하는 요소이다. 이에 따라, 철로 부근의 진동 및 소음에 대한 모니터링 시스템의 필요성이 증대되고 있으나, 레일의 조도상태 및 방진재 사양 등 철도진동소음에 영향을 주는 인자를 충분히 포함하지 못하고 있으며, 측정 및 분석 데이터의 체계적인 관리, 축적 구조를 갖지 못하는 문제가 있다. 또한, 연구기관의 인위적인 데이터 양식의 사용으로 실용적이고 개방적인 구조를 갖추지 못해 실제 엔지니어링 현장에서 활용하기 어렵다. 이에, 본 논문에서는 실제 엔지니어들이 현장에서 취득하는 정보를 체계적이고 지속가능한 형태로 데이터베이스화 하는 일체의 시스템 구축에 대해 논한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.149-154
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• 2001

Ship owners are demanding quieter vessels since crews have become more sensitive to their acoustic environment. Accordingly, designers of shipyards need to respond intelligently to the challenging requirements of delivering a quiet vessel. In early design stage, to predict shipboard noise the statistical approach is preferred to other methods because of simplicity. However, since the noise characteristics of the ships vary continuously with the environments, it is necessary to update the prediction formula with data base management system. This paper describes the feature of database program with the prediction method. Database management programs with GUI, are applied to Intranet system that is accessible by any users. Statistical approach to the prediction of A-weighted noise level in ship cabins, based on multiple regression analysis, is conducted. The noise levels in ship cabins are mainly affected by the parameters of the deadweight, the type of ship, the relative location of engines and cabins, the type of deckhouse, etc. As a result of verification, the formulas ensure the accuracy of 3 ㏈ in 83 % of cabins.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.9
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• pp.703-712
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• 2003

This paper suggests a fuzzy expert system for fault diagnosis of rotating machinery, based on modulated databases. In the proposed system, alarm and trip levels are set based on ISO, considering operating condition, machinery type and maintenance history. Input signals for diagnosis, such as sub-and super-harmonic components of vibration and mean value, are normalized from 0 to 1 under the threshold level and otherwise equal to one so that chronic faults slightly below the threshold level can be monitored. The database for diagnosis consists of two modules: the well-known Sohre's chart module and if-then type rules. The Sohre's chart is utilized for the most common problems of high-speed turbomachinery, while the rule-based module, which was collected from many papers and reports, is for diagnosing peculiar faults according to the type of machinery. To infer the results from two modules, a fuzzy operation of Yager sum was adopted. Using a simulator constructed in laboratory, experimental verification was performed for the cases of unbalance and resonance which were intended. The experimental results show that the proposed fuzzy expert system has feasibility in practical diagnosis of rotating machinery.