• 환경영향평가
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• 제7권1호
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• pp.63-70
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• 1998

TCM has been used for many environmental impact assessments in Korea. But there was reported that an error was found in area source calculation of original TCM and modified. In this study, TUM(TCM-urban mode) and TRM(TCM-rural mode) were developed for urban and rural area by modification of original TCM. McElroy-Pooler dispersion parameter was used for area and point source in TUM, Pasquill-Gifford parameter was used for area and point source in TRM. And Irwin's vertical wind speed profile exponents were used for TUM and TRM. Then predicted value by TUM, TRM and a value from the same area and point data by CDM2, ISCLT3 were compared. And it was found that predicted value from point source by TUM, TRM was very similar to a value by CDM2, ISCLT3, and predicted value from area source by TRM was similar to a value by CDM2, ISCLT3. But predicted value from area: source by TUM was an half lower than a value by CDM2, ISCLT3.

• 소음진동
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• 제9권3호
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• pp.587-592
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• 1999

Piston slap is one of the sources producing engine block surface vibration and mechanical noise. To analyze piston slap-induced vibration, a realistic but simple model is proposed and verified experimentally. A piston is modeled by 3 degree of freedom system and an impact point between piston skirt and cylinder wall by 2 degree of freedom system. Numerical simulation estimates impact forces of piston in cylinder, and the engine block surface vibration response is predicted by the convoluton of the impact forces with measured impulse responses. Experimental verification on the predicted response has been also performed by using a commercial 4-cylinder diesel engine. the predicted and experimental vibration responses confirm that the suggested model is practically useful.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.877-881
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• 2001

In this paper, a model is developed that can predict insulation performance of sound barrier systems under the action of multiple random point impact. The predicted results are compared with the measured results obtained by using APAMAT II. The results show the error due to the difference between experimental environment and theoretical assumptions. The model is needed to be improved to obtain better agreement between predicted and measured results.

• 소음진동
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• 제10권3호
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• pp.474-479
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• 2000

Piston slap is not only one of the major sources of noise and vibration in internal combustion engines but also a cause of the deterioration of engine performance. The basic mechanism associated with the piston slap seems to be quite simple but the phenomenon is in fact complicated with regard to many mechanical elements associated, First of all the impact force of piston slap must be identified to estimate engine block surface vibration, In this paper model of collision point is proposed to calculate the impact force when slap surface vibration. In this paper model of collision point is proposed to calculate the impact force when slap occurs. The parameters of the model are estimated by employing the concept of point mobility, . The predicted and experimentally observed vibration results confirm that the proposed method is practically useful.

• 환경영향평가
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• 제9권1호
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• pp.13-24
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• 2000

This paper presents a study of water quality model applications in environmental impact statements which were submitted during recent years in Korea. Most of the applications have reported that the development projects would have significant impacts on the water quality, especially, of streams and rivers. The water quality models, however, were hardly used as an impact prediction tool. Even in the cases where models were used, calibration and verification studies were not performed and thus the predicted results would not be reliable. These poor model applications in environmental impact assessment can be attributable to the fact that there were no available model application guidelines as well as no requirements by the review agency. In addition, the expected waste loads were improperly estimated in most cases, especially in non-point sources, and the predicted parameters were not good enough to understand water quality problems expected from the proposed plans. The effects of mitigation measures were not analyzed in most cases. Again, these can be attributed to no formal guidelines available for impact predictions until now. A brief guideline is described in this paper, including model selection, calibration and verification, impact prediction, and analysis of effects of mitigation measures. The results of this study indicate that the model application should be required to overcome the current improper predictions of environmental impacts and the guidelines should be developed in detail and provided.

• 환경영향평가
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• 제9권1호
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• pp.25-37
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• 2000

This paper presents a study of hydrological and hydraulic model applications in environmental impact statements which were submitted during recent years in Korea. In many cases (almost 70 %), the hydrological and hydraulic changes were neglected from the impact identification processes, even if the proposed actions would cause significant impacts on those environmental items. In most cases where the hydrological and hydraulic impacts were predicted, simple equations were used as an impact prediction tool. Computer models were used in very few cases(5%). Even in these few cases, models were improperly applied and thus the predicted impacts would not be reliable. The improper applications and the impact neglections are attributed to the fact that there are no available model application guidelines as well as no requirements by the review agency. The effects of mitigation measures were not analyzed in most cases. Again, these can be attributed to no formal guidelines available for impact predictions until now. A brief guideline is presented in this paper. This study suggested that the model application should be required and guided in detail by the review agency. It is also suggested that the hydrological and hydraulic items shoud be integrated with the water quality predictions in future, since the non-point source pollution runoff is based on the hydrologic phenomena and the water quality reactions on the hydraulic nature.

• 한국항공우주학회지
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• 제49권3호
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• pp.197-204
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• 2021

유도탄의 비행 시험 중 고장 또는 비정상적인 기동이 발생하는 경우 비행을 계속하지 않도록 의도적으로 자폭한다. 이때 파편이 발생하며 안전 지역을 벗어났는지 여부를 실시간으로 추정하는 것이 중요하다. 본 논문에서는 Fully-Connected Neural Network(FCNN)를 이용하여 실시간으로 파편의 예상 낙하 영역 및 낙하 시간을 추정하는 방법을 제안한다. 많은 양의 학습 데이터 생성을 위해 Unscented Transform(UT)를 적용하였으며 신뢰도 확보를 위해 Monte-Carlo(MC) 시뮬레이션과 비교하여 파라미터를 선정하였다. 또한 제안한 방법의 추정 결과를 MC와 비교하여 성능을 분석하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2001년도 제16회 학술발표회 논문초록집
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• pp.91-94
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• 2001

A structural test of the wind turbine rotor blade must be required to evaluate the uncertainty in design assessment due to use of material, design concepts, production processes and so on, and the possible impact on the structural integrity. In the full-scale static strength test, the measuring parameters are strain, displacements, loads, weight and the center of gravity. There are test equipments, measuring sensors, a test rig and fixtures to obtain measuring parameters. In order to simulate the aerodynamics load, the three-point loading method instead of the one-point loading method is applied. There is slightly some difference between the measured results and the predicted results with the reference fiber volume fraction of 60%. However, the agreement between the measured results and the predicted results with the actual fiber volume fraction of 52.5% is good. Even though a slightly non-linearity from 80% loading to 100% loading, a linear static solution is sufficient for the design purpose as the amount of the non-linearity is relatively small. Comparison between measured and predicted strain results at the maximum thickness positions of the blade profile for 0.236R(5.56m), 0.493R(11.59m) and 0.574R(13.43m), under 20%, 40%, 60%, 80% and 100% loadings for the upper part of the blade. The predicted values are in good agreement with the measured values.

• 한국대기환경학회지
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• 제17권4호
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• pp.331-345
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• 2001

The increase of carbon monoxide in the ambient air due to the emissions from point sources without control was estimated using three -dimensional numerical models. The target area was Ulsan where one of the largest industrial complexes was located. As a typical example using numerical models for air quality impact analysis of criteria pollutants that will determine whether the air quality standards would be exceeded or not, the following approaches were suggested. They include: (1) investigation of pre-existing atmospheric conditions, (2) identification of major factors causing high concentrations, (3) selection of episode days. (4) preparation of three-dimensional meteorological data, (5) confirmation of agreement between measured and predicted concentrations in the emission conditions of episode days, and (6) estimation of the impact due to changes of the emission conditions. In the present work, daily meteorological conditions for the specific period were classified into four clusters of distinctive features, and the episode days were selected individually from each cluster. Emphasis was placed on the selection of episodes representing meteorological conditions conducive to high concentrations especially for point sources that were sensitive to the wind direction variations.

• Composites Research
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• 제25권5호
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• pp.147-153
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• 2012

본 논문에서는 복합재 적층판의 고속충격 관통에너지를 예측하는 방법 중 하나인 정적압입 관통 실험을 수행하였다. 정적압입 관통 에너지를 정확히 분석하기 위해서 세 가지 방법을 이용하였다. 첫 번째로 AE 센서 신호 변화를 이용해서 압입 관통 지점을 판단하고 관통 에너지를 구하는 방법, 두 번째는 관통된 시편에 다시 관통실험을 수행하여 두 에너지 차를 이용해서 구하는 방법, 세 번째는 재수행한 관통실험의 하중-변위 그래프에서 최대하중지점을 압입 관통 지점으로 판단하고 에너지를 구하는 방법이다. 위 방법들에 의한 관통에너지 예측 결과를 제시하였고 고속충격 실험 결과와 비교하여 타당성을 검증하였다.