• 한국소음진동공학회논문집
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• 제15권6호
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• pp.718-723
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• 2005

The purpose of this study is to present a fundamental data for evaluating aircraft noise of building site development. By the field experiments and the predicted equal noise level contours using the INM program, actual condition in the building site development arranged district was investigated. In order to get the results, Analysis of factors effected on noise level, sound level on the rate of increase to aircraft demand and difference on the aircraft noise levels according to floor level in apartment house was carried out. As a result the influence of the take-off and landing direction were appeared greatly. The influences of the height at receiving point, movement number of aircraft and increase to aircraft demand were appeared small And the influence of 1 day average WECPNL must be considered.

• Communications for Statistical Applications and Methods
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• 제22권5호
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• pp.475-485
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• 2015

Similar to regression, many measures to detect influential data points in discriminant analysis have been developed. Many follow similar principles as the diagnostic measures used in linear regression in the context of discriminant analysis. Here we focus on the impact on the predicted classification posterior probability when a data point is omitted. The new method is intuitive and easily interpretable compared to existing methods. We also propose a graphical display to show the individual movement of the posterior probability of other data points when a specific data point is omitted. This enables the summaries to capture the overall pattern of the change.

• Monthly Notices of the Royal Astronomical Society
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• 제496권4호
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• pp.4787-4821
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• 2020

The merging rate of cosmic structures is computed, relying on the ansatz that they can be predicted in the initial linear density field from the coalescence of critical points with increasing smoothing scale, used here as a proxy for cosmic time. Beyond the mergers of peaks with saddle points (a proxy for halo mergers), we consider the coalescence and nucleation of all sets of critical points, including wall-saddle to filament-saddle and wall-saddle to minima (a proxy for filament and void mergers, respectively), as they impact the geometry of galactic infall, and in particular filament disconnection. Analytical predictions of the one-point statistics are validated against multiscale measurements in 2D and 3D realizations of Gaussian random fields (the corresponding code being available upon request) and compared qualitatively to cosmological N-body simulations at early times (z ≥ 10) and large scales (≥5 Mpc h^-1). The rate of filament coalescence is compared to the merger rate of haloes and the two-point clustering of these events is computed, along with their cross-correlations with critical points. These correlations are qualitatively consistent with the preservation of the connectivity of dark matter haloes, and the impact of the large-scale structures on assembly bias. The destruction rate of haloes and voids as a function of mass and redshift is quantified down to z = 0 for a Lambda cold dark matter cosmology. The one-point statistics in higher dimensions are also presented, together with consistency relations between critical point and critical event counts.

• Nuclear Engineering and Technology
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• 제33권1호
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• pp.93-101
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• 2001

The spacer grid is one of the main structural components in the fuel assembly, which supports the fuel rods, guides cooling water, and protects the system from an external impact load, such as earthquakes. Therefore, the mechanical and structural properties of the spacer grids must be extensively examined while designing them. In this paper, a numerical method for predicting the buckling strength of spacer grids is presented. Numerical analyses on the buckling behavior of the spacer grids are performed for a various array of sizes of the grids considering that the spacer grid is an assembled structure with thin-walled plates and imposing proper boundary conditions by nonlinear dynamic finite element method using ABAQUS/Explicit. Buckling tests on several numbers of specimens of the spacer grid were also carried out in order to compare the results between the test and the simulation result. The drop test is accomplished by dropping a carriage on the specimen at a pre-determined position. From this test, the specimens are buckled only at the uppermost and the lowermost layer among the multi-cells, which is similar to the local buckling at the weakest point of the grid structure. The simulated results also similarly predicted the local buckling phenomena and were found to give good correspondence with the experimental values for the thin-walled grid structures.

• Steel and Composite Structures
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• 제46권4호
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• pp.525-538
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• 2023

This paper focuses on the energy absorption of lattice core sandwich structures of different configurations. The diamond lattice unit cell, which has been extensively investigated for energy absorption applications, is the starting point for this research. The energy absorption behaviour of sandwich structures with an expanded metal sheet as the core is investigated at low-velocity impact loading. Numerical simulations were carried out using ABAQUS/EXPLICIT and the results were thoroughly compared with the experimental results, which indicated desirable accuracy. A parametric analysis, using a Box-Behnken design (BBD), as a method for the design of experiments (DOE), was performed. The samples fabricated in three levels of parameters include 0.081, 0.145, and 0.562 mm² Cell sizes, and 0, 45, and 90-degree cell orientation, which were investigated. It was observed from experimental data that the angle of cells orientation had the highest degree of influence on the specific energy absorption. The results showed that the angle of cells orientation has been the most influential parameter to increase the peak forces. The results from using the design expert software showed the optimal specific energy absorption and peak force to be 1786 J/kg and 26314.4 N, respectively. The obtained R2 values and normal probability plots indicated a good agreement between the experimental results and those predicted by the model.

• 환경영향평가
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• 제32권4호
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• pp.203-213
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• 2023

우리나라 환경영향평가서의 대기모델 적용 실태를 조사하기 위하여 2021년부터 2022년까지 협의가 완료되어 환경영향평가정보지원시스템(EIASS)에 공개된 환경영향평가서를 분석한 결과 AERMOD가 89.0%로 가장 많이 사용되었다. AERMET과 AERMOD의 버전 불일치는 25.3%로 나타났으며, 산업단지 및 도시개발사업의 발생하는 오염물질 배출량 산정시 적용한 가동시간과 모델에 적용한 가동시간의 불일치는 50.6%로 나타났다. 군산지역의 단순 및 복잡지형에서 다양한 버전의 AERMET과 AERMOD 모델을 면오염원과 점오염원에 적용한 결과, AERMOD 버전 12(15181) 이후부터는 동일한 값을 나타내었다. 배출량은 24시간 가동을 기준으로 산정하고, 모델에는 주간 8시간 가동을 적용하는 가변 배출계수 옵션을 사용할 때, 예측농도는 단순 및 복잡지형에서 면오염원은 32.06~74.27%, 점오염원은 14.85~43.13% 축소되는 것으로 나타났다. 따라서 AERMOD 모델의 가변 배출계수 적용 오류를 방지하기 위해서는 환경영향평가서에 배출량 산정과정을 명확히 제시하고, 모델링 입력자료 구성에 대한 구체적인 설명이 요구되며, 환경영향평가 전문 검토기관에서는 보다 철저한 검토가 필요하다.

• 항공우주시스템공학회지
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• 제18권2호
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• pp.1-11
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• 2024

정보공유 기반의 네트워크 협업 유도탄에 대한 상대 충돌 각 유도기법을 불확실성과 외란이 존재하는 시스템에 적용했다. 협업 유도탄 시스템은 전이 축소 방향성 비순환 그래프로 표현되며, 그 구조에 따라 유도된 중앙집권형 및 분산형 유도기법을 소개했다. 또한, 소개된 유도기법을 유도탄의 통신 구조와 시스템 잡음 유무에 따라 비교하여 그 관계를 분석했다. 상대 충돌 각 제어 임무에서 분산형 정보공유 유도기법의 효과를 분석하기 위해 시스템 동역학에 잡음이 포함된 다수의 유도탄이 불확실성이 포함된 예상 요격 위치에 유도되는 상황을 가정하였다. 다양한 임무 환경에 대해 몬테카를로 시뮬레이션을 수행하였으며, 이를 통해 정보공유의 유무와 구조가 시스템에 미치는 영향을 분석했다.

• 환경영향평가
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• 제15권2호
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• pp.93-100
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• 2006

In general, the verification to prediction formula in a national road and the main street of a town has been used recklessly in Korea. Therefore we investigated the validity of an existing prediction formula (NIER(87, 99), TR-Noise, KLC(2002)) with correction relationship which was based on both the prediction formular from apartment complex in the field and height 1.5m from the surface level. On the results of measuring the noise level form an isolated distance, the noise level showed that it was 4.5~5.5dB(A) by reason of becoming 2 folder far from a source. From the distribution of noise level measured by the apartment floors, the measurement point (1st floor) was 58.7~71.4dB(A) at its lowest level and the middle floors (3, 5, 7 and 10) were the highest distribution of noise level. From the analysis results on the application validity to an existing prediction formular (NIER(87, 99), TR-Noise, KLC(2002)) in the height 1.5m, the correction coefficients were 0.95~0.96 and the measured values were reasonably close to the predicted values, indicating the validity and adequacy of the predicted models. KLC(2002) model was found accurate within 3dB(A) with 36 data out of the total 42 data, showing the most accuracy among the predict models. However, the developed models have to improve the accuracy with a various of factors.

• 한국해양환경ㆍ에너지학회지
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• 제13권4호
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• pp.234-240
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• 2010

연안개발로 인해 발생하는 해양환경 변화를 정확히 예측하여 해양환경을 효율적으로 관리하기 위해서는 정확한 조위 및 조류 분포에 관한 자료의 확보가 필수적이다. 그러나 현재 대부분의 환경영향평가에서는 조석 수치모의에서 제한된 조석분조 만을 사용하여 조위와 조류분포를 예측하여 많은 분조의 합성에 의해 발생되는 실제 조석현상을 정확하게 계산하지 못하고 있으며, 이로 인해 환경영향평가에 오류가 발생하고 있다. 본 연구에서는 제한된 분조의외해 개방경계에서 조화상수를 가지고도 연안에서 관측된 조위자료를 활용하여 실시간으로 정확하게 조위 및 조류 분포를 예측할 수 있는 방법을 제안하였다. 4개 분조에 의한 조위와 38개 분조에 의한 조차의 비 그리고 모의조차와 관측조차의 비를 가지고 보정한 조위 예측결과는 관측조위와 잘 일치하였다.

• 한국추진공학회지
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• 제23권1호
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• pp.93-100
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• 2019

터보펌프 인듀서에서 발생하는 캐비테이션은 시작점부터 점차 발달하여 임계점, 그리고 급격한 양정 하락으로 이어지는 붕괴점의 과정으로 진행된다. 본 연구에서는 터보펌프 인듀서에서 발생하는 캐비테이션 시작점에 대한 특성과 경험식을 사용한 예측을 평가해 보았다. 타원 평판의 캐비테이션 시작점 경험식은 터보펌프 인듀서의 시작점도 비교적 잘 예측하는 것으로 나타났다. 하지만, 선박용 프로펠러에서 이용되는 경험식의 경우 터보펌프 인듀서의 결과와 큰 차이를 보였다. 터보펌프 인듀서의 캐비테이션 시작점은 날개 수가 증가할수록 빨라졌지만, 현절비와는 무관한 것으로 나타났다.