• 대한공간정보학회지
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• 제18권1호
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• pp.89-97
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• 2010

삼면이 바다로 둘러싸인 우리나라에서 정밀 지오이드 모델 개발을 위해서 해상에서의 중력자료는 필수적인 요소이다. 기존의 연구에서 해상에서의 중력자료는 위성고도계자료에서 산출한 중력자료를 이용하여 처리하였으나, 측량장비의 발달과 측위 시스템의 개선 및 국내 선상중력자료의 취득으로 인해 보다 정밀한 중력 자료의 취득이 가능하게 됨에 따라 선상중력자료의 정밀도를 검증하고, 지오이드의 구축에 있어서 선상중력자료의 활용성을 분석해볼 필요가 있다. 이를 위해 국립해양조사원에서 지난 1997년부터 2007년까지 측정한 선상중력자료를 대상으로 에트뵈스(Eotvos) 효과 보정, 칼만 필터(Kalman Filter), 교차점 보정 등의 일관된 처리를 거쳐 평균 16.47 mGal, 표준편차 18.86 mGal의 프리에어이상값을 산출하였다. 산출된 선상중력 프리에어이상값의 정밀도는 DNSC08 위성고도계자료와 비교를 통하여 검증되었는데, 두 자료의 프리에어이상값의 차이는 평균 -0.88 mGal, 표준편차가 9.46mGal로 나타났다. 이러한 차이는 영외지역이나 섬의 분포가 많은 해안 지역에서의 선상중력자료를 확보하는데 있어서의 한계와 해저지형에 의한 영향이 상대적으로 선상중력자료에서 크게 나타나기 때문으로 판단된다. 향후 지오이드 모델 개발에 선상중력자료를 활용하기 위해서는 자료 취득의 한계를 극복하고 위성고도계 자료와의 연계에 대한 연구가 진행되어야 할 것이다.

• 한국음향학회지
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• 제10권2호
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• pp.68-77
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• 1991

• 한국음향학회지
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• 제10권2호
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• pp.78-84
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• 1991

• International Journal of Automotive Technology
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• 제8권1호
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• pp.67-73
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• 2007

This study analyzes the interior noise that is generated during acceleration of a passenger car in terms of car body structure and panel contribution. According to the transfer method, interior noise is classified into structure-borne noise and air-borne noise. Structure-borne noise is generated when the engine's vibration energy, an excitation source, is transferred to the car body through the engine mount and the driving system and the panel of the car body vibrates. When structure-borne noise resonates in the acoustic cavity of the car interior, acute booming noise is generated. This study describes plans for improving the car body structure and the panel form through a cause analysis of frequency ranges where the sound pressure level of the rear seat relative to the front seat is high. To this end, an analysis of the correlation between body attachment stiffness and acoustic sensitivity as well as a panel sensitive component analysis were conducted through a structural sound field coupled analysis. Through this study, via research on improving the car body structure in terms of reducing rear seat noise, stable performance improvement and light weight design before the proto-car stage can be realized. Reduction of the development period and test car stage is also anticipated.

• 한국대기환경학회지
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• 제34권2호
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• pp.356-365
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• 2018

While social networks have become very popular and powerful way of connecting people and sharing new information, they also effectively spread wrong or biased information to the public. We examine the so-called "Shandong peninsular rumor" that claims Chinese government is responsible for the increased air pollution in South Korea and Japan, by moving pollution-causing industries near Beijing to the Shandong peninsular which is close to South Korea. We demonstrate that the amounts of $NO_x$ and $SO_2$ emissions inferred by space-borne monitoring and regional air quality models show clear declining trends in past several years. We do not have any evidences to support the relation of Shandong peninsular emissions change to South Korean air quality.

• 소음진동
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• 제8권3호
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• pp.542-552
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• 1998

The noise sources, structure-borne and/or air-borne, in machinery can be defined by their locations and strengths. However the locations of that noise sources are well known in many cases. In those cases, the problem can be defined as an inverse problem to known the strengths of the noise sources in the frequency domain, the modeling scheme is classified by thecoherent or incoherent source. This paper expands the basic concept to the case of the complex noise sources, in which the set of coherent and incoherent noise sources are matched with the noise of a real vehicle. The error factors in the experiment and the optimal number of the monopole sources to match the real suond filed are also investigated. The results of the noise source modeling of heavy machinery show that the incoherent and coherent/incoherent source models are applicable to the high frequency and the low frequency region, respectively. The noise source model also enables the noise source analysis to rank the contribution of real source group such as engine, T/M, exhuast, etc.

• 한국소음진동공학회논문집
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• 제18권1호
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• pp.26-34
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• 2008

This paper summarizes a design procedure of radiated noise from engine blocks of marine engines. This air-borne noise is one of the significant noise contributors including the aeroacoustic noise due to intake and exhaust and the re-radiation due to structure-borne noise. Excitation forces by engine operations are evaluated taking into account the power generation mechanism from the burning process to the subsequence motion of internal parts; piston, connecting rod, and crank shaft. The acoustic transfer vector method is incorporated to effectively simulate the radiated noise field under the various operation conditions. A contribution analysis for the various excitations to the radiated noise is conducted. It is found that the firing pressure is the main source of the radiated noise, and so the structure of the cylinder can be modified to significantly reduce the radiated noise from the engine block.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.830-833
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• 2004

An indoor package air-conditioner (PAC) has complex noise sources such as motor noise and fluid noise caused by the fan motor, heat transfer and shroud. Sound intensity techniques and ODS(Operational deflection shape) techniques are applied to identify the noise characteristics of an indoor air-conditioner's cabinet. The sound intensity is used to visualize the noise source locations. and the ODS to visualize the vibration pattern and to obtain the dynamic characteristics of the noise source. Acoustic intensity and operational deflection distribution are obtained in space domains as well as frequency domains. Using the visual information of source locations and its dynamic characteristics, the damping patch is applied to reduce structure borne noise in the cabinet. As a result, the noise emitted by the cabinet is reduced by 5dB.

• 한국대기환경학회지
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• 제16권1호
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• pp.69-77
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• 2000

This paper summerizes the results of the first proficiency testing program for achieving the analytical quality assurance of anions and metal ions in air borne particles in Korea. This program covered the chemical testing of anions(Cl-, NO3-, SO42-) and metals(Fe, Pb, Zn) in qeueous solution. The exercies was conducted by the Measurement & Analysis Committee of Korean Society for Atmospheric Environment(KOSAE). Pilot lab. was Division of Chemical Metrology and Materais Evaluation in Korea Research Institute of Standards and Science(KRISS). A total of 11 laboratories participated in the program. Two samples of 100mL in low density polyehylene bottles were supplied to participating laboratories. The proficiency testing results were interpreted by two graphical methods, Youden polt and x-Charts(control chart).

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.106.4-106
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• 2001

The current research field to find near-optimum solutions explores in a small population, which is coined as Micro-Genetic Algorithms (${\mu}$GAs), with some genetic operators. Just as in the Simple-Genetic Algorithms (SGAs), the ${\mu}$GAs work with encoding population and are implemented serially. The major difference between SGAs and ${\mu}$GAs is how to make reproductive plan for more better searching strategy due to the population choice. This paper is conducted to implement ${\mu}$GAs in order to achieve fast searching for more better evolution and associated cost evaluation in global solution space. To achieve this implementation, the Air-Borne Selection (ABS) for a new reproductive plan is developed as new strategic conception for ${\mu}$GAs. In this paper, it is shown that the ${\mu}$GAs implementation reaches a near-optimal region much earlier than the SGAs implementation. The superior ...