• Journal of the korean Society of Automotive Engineers
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• v.11 no.1
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• pp.57-67
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• 1989

Acoustic intensity method is applied to a 4-cylinder gasoline engine in order to identify the noise sources and the response characteristics. Acoustic intensity is analyzed by 1/3 octave band filter for each center frequency. Radiational characteristics of acoustic intensity at overall and the maximum intensity level are represented by using the contour and three-dimensional plot. It is verified that this method is effective to the assessment of engine noise. It can be found that the maximum intensity is radiated from the front side of the engine under idling condition and the right side of it under 2, 000 rpm running with no loading condition at overall level, and also that the maximum intensity is radiated from the oil pan and the intake and exhaust manifold at the center frequency of 100 Hz.

• The Journal of the Acoustical Society of Korea
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• v.16 no.5
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• pp.36-42
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• 1997

This paper purposes the measurement method of vibration intensity in building structure which is a method of measuring the intensity and the flow of vibration energy. We derived basic theory and measuring theory for a simple beam, and comparison of the experimental results with calculated results. As a result, according to the calculated value from acceleration distribution and the measurement result from the method of vibration intensity under the condition except near field of measurement zone. The measured results, show that this method is useful for measuring the vibration energy flow in building structure.

• The Journal of the Acoustical Society of Korea
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• v.12 no.3
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• pp.68-75
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• 1993

포락선 인텐시티는 신호의 진폭 변화에 비해 상대적으로 천천히 벼놔한다. 본 논문에서는 이러한 성질을 이용하여 종래의 순시 음향 인덴시티법을 수정한 새로운 포락선 인텐시티법을 제안하여 비정상 신호 해석에 이 기술을 적용하였다. 이 기술의 유효성은 반사체가 있는 무향실 내의 충격성 음원에 대해 수치계산 결과와 실험결과의 비교로부터 검증되었고 또한, 이 기술은 무향실 및 잔향실 내의 평판 타음 음원의 지향특성 해석에 응용되었다. 수치계산 결과 및 측정결과는 일치하였고, 제안된 방법은 종래의 순시 인텐시티법보다 특히 과도특성을 갖는 충격성 음원 분석에 보다 유효함이 확인되었다.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.72-77
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• 2024

Recently, the necessity for sound source localization has grown significantly across various industrial sectors. Among the sound source localization methods, sound intensimetry has the advantage of having high accuracy even with a small microphone array. However, the increase in localization error at high Helmholtz numbers have been pointed out as a limitation of this method. The study proposes a method to compensate for the bias error of the measured sound intensity vector according to the Helmholtz numbers by applying deep learning. The method makes it possible to estimate the accurate direction of arrival of the source by applying a dense layer-based deep learning model that derives compensated sound intensity vectors when inputting the sound intensity vectors measured by a tetrahedral microphone array for the Helmholtz numbers. The model is verified based on simulation data for all sound source directions with 0.1 < kd < 3.0. One can find that the deep learning-based approach expands the measurement frequency range when implementing the sound intensimetry-based sound source localization method, also one can make it applicable to various microphone array sizes.

• The Journal of the Acoustical Society of Korea
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• v.6 no.3
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• pp.17-22
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• 1987

This study is to propose more reliable test method in evaluating the sound insulation performance of building element in fields. This method involves the measurements of the incident acoustic intensity and transmitted surface intensity. The incident intensity is determined from measurements of the space averaged sound pressure level in source room. The transmitted surface intensity is measured directly using one microphone and one accelerometer. The results of experiments indicate that this new method makes it possible to give more reliable data than the conventional field test method. The values of trans-mission loss measured by this new method are compared favorably with those obtained using the sound intensity method and theoretical calculation(mass law).

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.31-31
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• 2022

기후변화, 물 부족, 인구 증가와 도시화로 인한 물 수요 증가, 수질 악화, 노후화된 인프라와 같은 세계적인 물문제의 증가로 인해, 도시 물순환 시스템 관리는 더 큰 어려움을 겪고 있다. 취수, 도·송수, 정수처리, 배·급수, 용수 사용, 하수 집수, 하수 처리, 재이용 및 배출 과정을 포함하는 도시 물순환 시스템의 과정은 매우 에너지 집약적인 활동이며, 이와 같은 에너지 소비는 탄소 배출과 양의 직접적인 상관관계가 있다. 따라서 자원 관리 및 데이터 관리를 최적화하기 위해 넥서스 관점의 접근법이 도시 물순환 시스템에 점차적으로 도입되고 있는 추세이다. 도시 물순환 시스템 넥서스에서는 일반적으로 에너지 인텐시티로 표현되는 물을 위한 에너지를 이해하는 것이 중요하다. 에너지 인텐시티의 차이는 기후(연평균 강수량, 단기 기후 변동성, 기후패턴 등), 지리적 특징(표고차, 평지비, 위치 등), 시스템 특성(총급수량, 인구, 인구밀도, 관로 연장 등) 및 운영관리 효율(수압, 누수율, 에너지 효율 등)과 밀접한 관계가 있다. 그리고 도시 물순환 시스템에서 에너지 관리를 증진시킨 방안은 유지관리 효율 개선(물·에너지 관리전략, 물손실 관리, 수요 관리 및 수요 대응 등), 신기술 도입, 그리고 에너지 회수로 나누어진다. 본 연구에서는 기존 문헌의 자료를 분석하여 도시 물순환 시스템의 각 공정별 에너지 인텐시티를 분석하였으며, 시스템 다이나믹스를 적용하여 다양한 도시 여건(인구, lpcd, 누수율, 취수원, 에너지 인텐시티)에서 외부영향(기후변화, 도시화)과 운영효율 변동(운영효율 향상, 신시술 도입)에 따른 도시 물순환 시스템 내 자원 사용 및 이동을 분석하였다. 에너지 인텐시티는 전체 도시 물순환 시스템, 상수 시스템, 하수시스템에서 각각 2.334 kWh/m³, 1.029 kWh/m³, 1.024 kWh/m³를 나타내었으며, 용수사용, 담수화, 재이용 과정에서는 매우 높은 값이 나타났다. 에너지 인틴시티의 값은 외부 영향에 크게 좌우되는 것으로 분석되었으며, 운영효율의 변동에 따라서 물 및 에너지 사용량은 변화하였지만 에너지 인텐시티의 변동은 크지 않았다. 이에 따라 도시 물순환 시스템을 넥서스 관점에서 관리하기 위해서는 에너지 인텐시티 이외에 물 및 에너지 사용량, 유수수량 관점 에너지 인텐시티, 사용수량 관점 에너지 인텐시티를 종합적으로 고려하는 것이 필요하다.

• Journal of the Korea Society of Computer and Information
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• v.19 no.10
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• pp.35-42
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• 2014

It is possible to improve the obstacle avoidance capability by training and recognizing the obstacles which is in certain indoor environment. We propose the technique that use underlying intensity value along with intensity map from RGB-D image which is derived from stereo vision Kinect sensor and recognize an obstacle within constant distance. We test and experiment the accuracy and execution time of the pattern recognition algorithms like PCA, ICA, LDA, SVM to show the recognition possibility of it. From the comparison experiment between RGB-D data and intensity data, RGB-D data got 4.2% better accuracy rate than intensity data but intensity data got 29% and 31% faster than RGB-D in terms of training time and intensity data got 70% and 33% faster than RGB-D in terms of testing time for LDA and SVM, respectively. So, LDA, SVM have good accuracy and better training/testing time to use for obstacle avoidance based on intensity dataset of mobile robot.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.3
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• pp.62-73
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• 2001

The interest in evaluation of structural intensity arises for practical reasons, because net energy flow distribution offers information of energy transmission path, positions of sources, and sinks of vibration energy. In this paper, structural intensity analysis of local ship structures using finite element method(FEM) is carried out. The purpose of this analysis is to evaluate the relative accuracy according to mesh fineness. The structural intensity of unstiffened and stiffened plates varying their mesh fineness is analyzed and the results are compared with those obtained by the assumed mode method. As results, the proper mesh size in qualitative/quantitative structural intensity analysis of plate structures is proposed. In addition, the propagation phenomenon of vibration energy is investigated for the thickness-varying flat plate, L-type plate, and box-girder structures.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.4
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• pp.76-86
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• 1998

Structural intensity of plates experiencing bending vibration is analytically evaluated using the modal analysis based on assumed mode method. To evaluate the convergence of structural intensity according to the number of superposition modes, the power obtained by structural intensity integration over the closed curve containing the excitation source is compared with the power injected into plates. The erect of power reduction due to the material internal loss is evaluated using the intensity around a localized damping point, In addition, the dominant component among internal forces in the power transfer by the bending vibration of plates and the change of power flow due to stiffener are also investigated.

• Journal of KSNVE
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• v.7 no.4
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• pp.589-596
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• 1997

A energy equation for a thin plate and surrounding fluid is derived. The equation essentially determines the relation between internal loss of thin plate, energy of acoustic radiation, and structure intensity. We attempted to use this relation to measure internal loss of thin plate. The significance of this approach is that internal loss at any point of a thin plate can be measured. The quality of this measure is dicated by the accuracy of associated measurement systems such as structure and acoustic intensity measurements. A strain gauge bridge system has been developed to measure structure intensity of thin plate. Its performance is tested by experiments.