• 품질경영학회지
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• 제43권3호
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• pp.273-288
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• 2015

Purpose: In this study, we apply environmental stress screening (ESS) to battle management system (BMS) of a tank and use the ESS profile based on production process data, guided by MIL-HDBK-781/344/2164. Methods: To optimize ESS Profile of the BMS of a tank, we estimate ESS model parameters (e.g., defect density, screening strength) using primary production failure reporting and corrective action system (FRACAS) data of military supply contract firm. Results: First, we collect the Primary production FRACAS data of military supply contract firm. Second, we compute curve fitting approach to find patent defect density and latent defect density using FRACAS data. Third, we solve the equation of Defect Density(patent defect density + latent defect density)($D_{IN}$) and Screening Strength(SS) Using second step data. As a result of analysis according to the order, we calculate $D_{IN}$(Temperature stress case : 74.02, Vibration stress : 10.252) and : SS(Temperature stress case : 0.4632, Vibration stress : 0.4142) and confirm the Condition II-D based on MIL-HDBK-344. According to Condition II-D, it is necessary to modify existing ESS profile through decreasing the $D_{IN}$ and increasing the SS. Conclusion: Identification of defect causes through ESS approach reduce defect densities for production. It provides feedback to a lessons-learned data base to avoid similar problems on next generation tank BMS.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.106-112
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• 1998

A numerical experiment is conduced to study the wave screening effectiveness of wave barriers which are constructed to reduce the ground-transmitted vibration. The finite element method is used for the simulation of the wave propagation behavior. In order to reduce the computational burden the absorbing boundary's one employed. Validity of the numerical model is checked by comparing the results with the published data. The screening effectiveness of the in filled trenches is then studied for different trench dimensions and material properties.

• 한국항행학회논문지
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• 제25권5호
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• pp.313-319
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• 2021

본 논문에서는 MIL-HDBK-344A 기반의 ESS(environmental stress screening) 시험 에 대해 소개하고, 유도탄 내부 케이블의 ESS 시험에 대한 목적과 규격 설정 및 시험 방안에 대하여 확인하였다. ESS 시험구성은 온도 순환과 랜덤 진동의 환경 자극으로 이루어져 있으며, 핸드북의 절차를 기반으로 유도탄 내부 케이블의 ESS 시험 규격 설정과 시험 구성을 제시하고, 진동 시험을 위한 유도탄 내부 케이블의 ESS 시험을 위한 치구를 제작하였다. 스크린 강도(SS; screening strength)를 통해 결정되는 결함 감지 확률은 일회성으로 사용되는 유도탄의 신뢰성에 부합되도록 선정하였고, 또한 ESS 시험 중 유도탄 내부 케이블의 검사방법과 고려해야 할 점에 대하여 소개하였다.

• 항공우주기술
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• 제5권2호
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• pp.102-107
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• 2006

본 논문은 위성체 동적 환경의 발사체 구조에 의해 전달된 저 주파수의 과도 진동과 불 규칙적인 가속력으로 구성되어 있다. 저 주파수에서의 과도 진동은 보통 진동수 100 ~ 200Hz에 이르는 정현파로 근사되며 주로 예비설계에 사용된다. 그리고, 랜덤 환경은 발사체의 연소와 분리 단계, 외부 공력소 음에 의한 구조적 진동에 의해 발생한다. 이는 발사체 구조물을 통하여 위성체와 발사체의 어댑터 구조로 전달된다. 이러한 동적환경 중에서 랜덤 진동 해석은 위성체에 수행되는데, 특히, 위성체 내의 전자 박스(장비) 는 실제 상황에 가깝게 하여 검증하기 위해 랜덤 진동 실험을 통해 설계 되야 한다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 추계학술대회 논문집
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• pp.29-33
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• 2002

A procedure of free span and fatigue analysis of offshore pipelines was made per DNV-RP-F105, 2002. The new method includes the axial force and deflection load in pipelines. The screening criteria were used to calculate the allowable span lengths. The screening criteria allow small amplitudes of vortex-induced vibration due to wave and current loading. However, the induced pipe stress is very small and usually below the limit stress of a typical S-N curve. A simplified method was established to calculate the fatigue damage due to long-term current distribution. The long-term current statistics was assumed with a 3-parameter Weibull distribution. The fatigue damage was estimated for the span lengths obtained from the screening criteria for various conditions. Sample calculations show the effect of axial force for various boundary conditions.

• 한국소음진동공학회논문집
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• 제14권12호
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• pp.1279-1286
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• 2004

This paper continues companion paper, part I : measurement and analysis. As shown in companion Paper, information and energy in monaural signal is quite different from that of binaural signal. In this paper, difference between monaural and binaural signal of transportation noise are investigated in subjective response test. We executed hearing screening test before giving a subject response test and excluded subjects who had physical hearing loss. An annoyance response test was conducted using headphone to avoid cross-talk effect in binaural testing. Percentage of highly annoyed under binaural signal reproduction is higher than percentage of highly annoyed under monaural signal reproduction. Result implies binaural reproduction technique is proper for a study of human response to short-term noise exposure in a headphone simulated-environment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.335-341
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• 2001

The bubble cavitation and cloud cavitation are the major sources of cavitation-induced sound and vibration. A numerical method which predicts the trajectory and volume change of a cavity is developed, to predict the cavitation noise of a body. It is shown, by using the numerical method, that the cavitation inception and events rate is strongly dependent on the screening effect caused by the pressure gradient around a body, which is confirmed experimentally. Additionally, the effectiveness of a cavitation control method utilizing air injection is investigated experimentally. It is demonstrated that the noise level of the cloud cavitation can be significantly reduced by the air-injection method.

• 대한후두음성언어의학회지
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• 제6권1호
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• pp.22-26
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• 1995

Change of voice, espicially hoarseness show irregular vibration of vocal cord. So, computerized acoustic analysis has presented many acoustic parameters for objective evaluation of voice. We objectively investigated the vocal vibration of normal persons and hoarseness patients in Korea. The RAP(relative average perturbation), PPQ(pitch period perturbation quotient) and APQ(amplitude perturbation quotient) of normal persons were compared with that of hoarseness patients with multidimensional voice program for the possibility of distinguishing the pathologic vocal vibration from normal. Authors agree that RAP, PPQ and APQ showed interesting differences between the normal and the hoarseness patients by the multivariate statistical analysis. In conculusion, relative average perturbation, pitch period perturbation and amplitude perturbation quotient might be meangingful screening parameters distinguishing hoarseness patients from normal.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 봄 학술발표회 논문집
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• pp.383-389
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• 1998

A numerical study is conducted to examine the wave scattering at infilled trenches which may be constructed to reduce the ground-transmitted vibration. The finite element method is used for the simulation of the wave propagation in the semi-infinite region. In order to keep the computational burden manageable, the absorbing boundaries are employed. The numerical technique is validated by modeling a published problem. The results are shown to be in good agreement with the published data. The screening effectiveness of the infilled trenches is then studied for different trench dimensions and material properties.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.727-732
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• 2009

The objective of this study is to analyze and evaluate design factors relating to sound reduction performance in dry wall system. The main contents of this study are as follows. 1) Analysis and pre-evaluation of sound reduction performance of drywall system ; The sound reduction performance was pre-evaluated by INSUL simulation and these results of analyzing walls were analyzed by screening DOE(design of experiment) for selecting major factors that dominant influence the sound reduction performance. These main factors relating to sound reduction performance can be used for development of 1st grade sound reduction performance drywall system. 2) Design and evaluation of 1st grade sound reduction performance drywall system; The evaluation test of the sound reduction performance gave vaues higher than 1st grade (Rw+C=64). When campared with existing dry wall system, respectivelly, the new system shows performance higher than 8 dB.