• 한국항공우주학회지
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• 제43권4호
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• pp.341-348
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• 2015

본 논문에서는 일반적인 발사체의 형상에 대하여 몬테카를로 시뮬레이션을 적용하여 분리 유격 분석을 수행하였다. 단 분리는 매우 짧은 시간동안 이루어지며, 매우 많은 운동 변수가 관계되고 충돌 발생시 발사 실패가 나타나는 매우 중요한 비행 이벤트이다. 다양한 오차요인이 무작위(random)로 발생하는 경우에도 설정된 유격조건 내에서 분리가 됨을 확인하기 위해 일반적인 발사체 형상에 대한 단 분리 분석을 수행하였다. 몬테카를로 분석 기법을 발사체 단 분리 분석에 적용함으로서 단 분리 운동시 확률적인 결과들을 제시하였다.

• 한국전산유체공학회지
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• 제9권1호
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• pp.41-47
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• 2004

A successful store separation analysis tool, MSAP(Multi-body Separation Analysis Program) has been applied to F/A-18C/JDAM CFD Challenge Ⅱ. The challenge was devised to challenge CFD community to use CFD methodologies to predict and match the trajectory of a JDAM MK-84 separating from F/A-l8C. Trajectory simulations for two flight conditions were performed. Comparison between computed and measured flight trajectories for both conditions shows a good agreement.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 추계 학술대회논문집
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• pp.89-94
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• 2003

A successful store separation analysis tool, MSAP(Multi-body Separation Analysis Program) has been applied to F/A-18C/JDAM CFD Challenge II. The challenge was devised to challenge CFD community to use CFD methodologies to predict and match the trajectory of a JDAM MK-84 separating from F/A-l8C. Trajectory simulations for two flight conditions were performed. Comparison between computed and measured flight trajectories for both conditions shows a good agreement.

• 한국항행학회논문지
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• 제21권1호
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• pp.30-35
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• 2017

항행안전무선시설은 전파를 이용하여 항공기 안전운항에 필요한 정보를 제공하는 매우 중요한 요소이다. 최근 전파를 이용하는 무선시설이 크게 늘어남으로써 인접채널에 의한 항공주파수 전파방해 가능성은 매우 커지고 있다. 뿐만 아니라, 항행안전시설을 위협하는 불규칙한 전파방해 및 인공위성을 활용하는 위성항행시스템 주파수 사용이 급증하고 있어 항공전파 안전성 확보가 시급하다. 본 논문에서는 국내 항행시스템의 종류별 특성과 주파수를 조사하였고, 분석 프로그램 개발을 위하여 국내외 지리적 분리간격 기준을 분석하였다. 또한, 항행안전시설 설치 시 인접시설에 영향이 없도록 국제규정을 적용한 항행안전무선시설의 지리적분리간격 분석 프로그램을 개발하였다. 본 분석 프로그램은 운영현황 표시 기능, 신설시 지리적 분리 시뮬레이션 기능, 미부합 시 조치방안 제안 기능 등을 제공한다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.238-245
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• 2000

Separation strips are temporary joints to prevent crack due to stress induced by shrinkage. In this study, an analysis procedure considering separation strip is proposed to decide proper casting time of separation strip and cracking stresses of the example building slabs are calculated using this procedure. The result of the example high rise building shows that the percentage of cracking stress to the modulus of fracture is 43.4% when closing of separation strip are 30 days after placing the slab, so it is enough time for the separation strip in each floor to absorb the effects of shrinkage.

• Nuclear Engineering and Technology
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• 제29권5호
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• pp.361-367
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• 1997

The phase separation in ferrite phase of duplex stainless steel is the primary cause of thermal aging embrittlement of the LWR primary pressure boundary components. In this study the phase separation of simulated duplex stainless steel was detected by Mossbauer spectroscopy and magnetic property analysis by VSM(Vibrating Specimen Magnetometer). The simulated duplex stainless steels, Fe-Cr binary, Fe-Cr-Ni ternary, and Fe-Cr-Ni-Si quarternary allots, were aged at 370 and 40$0^{\circ}C$ up to 5,340 hours. It was observed from Mossbauer spectra analysis that internal magnetic field increases with aging time and from VSM that the specific saturation magnetization and Curie temperature increase with aging time. These result are indicative that phase separation into Fe-rich region and Cr-rich region is caused by thermal aging in the temperature range of 370~40$0^{\circ}C$ In cases of specimens containing Ni, the increase of specific saturation magnetization is much higher. This implies that Ni seems to promote Fe-Cr interdiffusion, which accelerates the phase separation into Fe-rich $\alpha$ phase and Cr-rich $\alpha$' phase.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 추계 학술대회논문집
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• pp.145-150
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• 2004

In this study the numerical analysis on staging flow with forward ejector is conducted. The forward ejector plays a vital role in staging, which jets out from aftbody. This staging environment needs careful flow analysis for securing staging safety Present study investigates the steady inviscid staging flow phenomena with variation of separation distance. The performance index is forebody base pressure coefficients. The three dominant flow phenomena are observed according to separation distance which could be told as impinging stage, cavity vortex dominancy stage, and pure base flow characteristics stage. Impinging stage shows high thrust for forebody as one might think. However, important point is that cavity vortex dominancy stage can be more favorable for separation than impinging stage as one simply think in certain separation distance.

• 분석과학
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• 제36권6호
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• pp.259-266
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• 2023

The demand for rare-earth elements (REEs) is increasing owing to their significance as prominent materials in electronics, high-tech industries, geological research, nuclear forensics, and environmental monitoring. In general, the utilization of REEs in various applications requires the use of chromatographic techniques to separate individual elements. However, REEs have similar physicochemical properties, which makes them difficult to separate. Recently, several studies have examined the separation of REEs using LN resin as the stationary phase and aqueous nitric acid and hydrochloric acid solutions as eluents. Using this method, light REEs have been separated using dilute acid solutions as the eluent, whereas heavy REEs are separated using solutions with high acid concentrations. To increase the separation resolution between different REEs, either the column length or resin size is changed. In addition, the suggested methods are implemented to decrease the analysis time. This review presents technical information on the chromatographic separation of REEs using the LN resin and discusses the optimal experimental conditions.

• The Journal of the Acoustical Society of Korea
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• 제21권4E호
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• pp.146-155
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• 2002

We present a new technique for achieving source separation when given only a single charmel recording. The main idea is based on exploiting the inherent time structure of sound sources by learning a priori sets of time-domain basis functions that encode the sources in a statistically efficient manner. We derive a learning algorithm using a maximum likelihood approach given the observed single charmel data and sets of basis functions. For each time point we infer the source parameters and their contribution factors. This inference is possible due to the prior knowledge of the basis functions and the associated coefficient densities. A flexible model for density estimation allows accurate modeling of the observation, and our experimental results exhibit a high level of separation performance for simulated mixtures as well as real environment recordings employing mixtures of two different sources. We show separation results of two music signals as well as the separation of two voice signals.

• 한국음향학회지
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• 제21권4호
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• pp.146-146
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• 2002

We present a new technique for achieving source separation when given only a single channel recording. The main idea is based on exploiting the inherent time structure of sound sources by learning a priori sets of time-domain basis functions that encode the sources in a statistically efficient manner. We derive a learning algorithm using a maximum likelihood approach given the observed single channel data and sets of basis functions. For each time point we infer the source parameters and their contribution factors. This inference is possible due to the prior knowledge of the basis functions and the associated coefficient densities. A flexible model for density estimation allows accurate modeling of the observation, and our experimental results exhibit a high level of separation performance for simulated mixtures as well as real environment recordings employing mixtures of two different sources. We show separation results of two music signals as well as the separation of two voice signals.