• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.12
• /
• pp.2100-2108
• /
• 2001

The impinging tones by high-speed plane jets are experimentally investigated to study the edgetone characteristics. Experiment used a slit nozzle and a wedge system to generate edgetones. The jet in the experiment is varied from low to high subsonic speed to obtain the effect of the speed on the frequency characteristics of impinging tones. The experimental data obtained previously fur edgetones and platetones by various nozzles are compared with the present edgetone data. And the condition of tone generation, the frequency ranges, the effective source point and the sound pressure level are compared and discussed. It is found that the jet speed has no diect influence on the impinging tone characteristics. Regardless of the jet speed, the effective source point is about a quarter wavelength downstream from the edge tip. With increase in jet speed, the influence of the nozzle configuration is decreased and the operating frequencies show good coincidences by normalized parameters based on the slit thickness.

• Journal of IKEEE
• /
• v.24 no.1
• /
• pp.254-259
• /
• 2020

This paper is the implementation of the conversion system from image to music based on intentional synesthesia. The input image based on color, texture, and shape was converted into melodies, harmonies and rhythms of music, respectively. Depending on the histogram of colors, the melody can be selected and obtained probabilistically to form the melody. The texture in the image expressed harmony and minor key with 7 characteristics of GLCM, a statistical texture feature extraction method. Finally, the shape of the image was extracted from the edge image, and using Hough Transform, a frequency component analysis, the line components were detected to produce music by selecting the rhythm according to the distribution of angles.

• Journal of Power System Engineering
• /
• v.11 no.1
• /
• pp.82-91
• /
• 2007

기존의 2차원 FDLB 모델(D2Q21)에서 비열비 ${\gamma}$는 공간의 차원수(D)에 의존한다. 즉, 2차원 공간의 계산에서는 ${\gamma}=(D+2)/D=2.0$밖에 취할 수 없으며, 공기와 같은 실체기체를 전산모사 하기에는 여러 어려움이 있다. 이러한 이유 때문에 문헌[1]의 LBM에서 제안된 조정 가능한 비열비 모델을 2차원 FDLB모델에 적용하여 자려발생 에지톤(edgetone)의 수치계산이 수행되었다. wedge의 선단각도가 ${\alpha}=23^{\circ}$(Case I) 및 $20^{\circ}$(Case II)를 갖는 2가지 모델이 설정되었으며, 노즐출구에서 wedge선단까지의 거리 w/d는 $3d{\sim}12d$사이에서 주어졌다. edgetone은 노즐로부터 나온 분류와 edge의 상호작용으로 이난 음압(sound pressure)의 차에 의해서 소음이 발생하며, 이 음압은 다시 상류의 분류에 영향을 미쳐 분류의 변동을 가져온다. w/d가 ??9d이하인 경우, 피드백(feedback) 메커니즘에 기인한 주기적인 운동이 발생하지만, w/d가 큰 ??9d이상인 경우에는 분류의 불안정성 때문에 규칙적인 분류의 운동은 보이질 않으며, 이는 기존의 연구결과들과 잘 일치함을 보였다. 본 연구에서 적용된 모델을 이용하여 공기와 같은 2원자 기체의 비열비 ??${\gamma}=1.4$를 갖는 유체에 있어서 공력 소음의 수치예측이 가능하다는 것을 확인하였다.

• Journal of Korean Society of Forest Science
• /
• v.102 no.1
• /
• pp.113-121
• /
• 2013

It has been known that edges of forest fire areas play significant roles in post-fire change of forest ecosystem and recovery process. The purpose of this study was to analyze the relationships between edge formation of burned forests and landscape characteristics with consideration on spatial autocorrelation. Samcheok fire site burned in 2000 was selected as the study area. Seven hundred fifty three of 500 $m^2$ grid cells were generated for measuring landscape characteristics. This study used the topographic variables including slop, elevation, topographic wetness index, solar radiation index and proportions of fuel and land use types. In delineating landscape characteristics correlation analysis with modified t-test were performed for exploring the relationships between edge formation and landscape characteristics. The results indicated that edge formation of burned forests was positively correlated with most variables including TWI, SRI, water, paddy, developed, farm, grass, bare soil, and negatively related with elevation, slope and all fuel types. Especially TWI (r=0.437) showed a strong positive correlation with edge formation. According to the results, edge of burned forests were likely formed when proportions of heterogeneous land use types were high with mild slope and low elevation.

• Journal of KSNVE
• /
• v.8 no.1
• /
• pp.146-156
• /
• 1998

To mitigate excessive noise from highways, and high speed rail road, it is often necessary to construct a noise barrier. Absorptive barroer attenuation solution is obtained for the problem of diffration of a plane wave sound source by a semi-infinite plane. A finite region in the vicinity of the edge has an highly absorbing boundary condition ; the remaining portion of the half plane is rigid. The problem which is solved is a mathematical model for a hard barrier with an absorbing edge. If the wavelength of the sound is much smaller than the length scale associated with the barrier, the diffraction process is governed to all intents and purpose by the solution to a standard problem of diffraction by a semi-infinite hard plane with an absorbent edge. It is concluded that the absorbing material that comprises the edge need only be of the order of a wavelength long to have approximately the same effect, on the sound attenuation in the shadow side of the barrier. Traffic noise is composed of thousands of sources with varying frequency content. To simplify noise predictions when barriers are present, an effective frequency of 550Hz may be used to represent all vehicles. The wavelength of sound at f=550Hz for traffic noise is about 2 feet. According to the above conclusion, an absorptive highway noise barrier is only needed to cover to cover approximately a 2 foot length of absorbing material. It would be more economical to cover only the region in the immediate vicinity of the edge with highly sound obsorbent material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.11a
• /
• pp.162-162
• /
• 2009

Optical bounce which occurs by over twist of the liquid crystal (LC) director has a problem of response time in fringe-field switching (FFS) modes. After removing the electric field, effective birefringence ($d{\Delta}n_{eff}$) at the edge of pixel electrode meets the $\lambda/2$ phase instantly, since tilt angle of LC directors at that position suddenly decreases compared to twist angle. In this paper, based on the careful analysis, origin of optical bounce has been explained.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.1
• /
• pp.50-55
• /
• 2004

In this study, slit-tones by plane impinging jet are investigated experimentally over the whole subsonic flow range, especially at low speeds, in order to obtain the instability behaviour of impinging plane jet. Slit-tones are generated at low speeds associated with laminar shear layer instability as well as at high speeds associated with turbulent instability. Most of low-speed slit-tones are induced by symmetric mode instability unless the slit is not so wide, in which case antisymmetric modes are induced like edge-tones. It is found that the frequencies at low speeds ate controled by the unstable condition of the vortex at the nozzle exit and its pairings by which the frequencies are decreased by half. In the case of symmetric modes related with low-speed slit-tones, frequencies lower than those associated with one-step pairings are not found.

• Journal of the Korean Vacuum Society
• /
• v.14 no.1
• /
• pp.17-23
• /
• 2005

Glow discharge mass spectrometry(GDMS) was used to determine the impurity concentrations of the deposited Cu films and the 6N Cu target. Cu films were deposited on Si (100) substrates at zero substrate bias voltage and a substrate bias voltage of -50 V using a non-mass separated ion beam deposition method. Since do GDMS has a little difficulty to apply to thin films because of the accompanying non-conducting substrate, we have used an aluminum foil to cover the edge of the Cu film in order to make an electrical contact of the Cu film deposited on the non-conducting substrate. As a result, the Cu film deposited at the substrate bias voltage of -50 V showed lower impurity contents than the Cu film deposited without the substrate bias voltage although both the Cu films were contaminated during the deposition. It was found that the concentration change of each impurity in the Cu films by applying the negative substrate bias voltage is related to the difference in their ionization potentials. The purification effect by applying the negative substrate bias voltage might result from the following reasons: 1) Penning ionization and an ionization mechanism proposed in the present study, 2) difference in the kinetic energy of accelerated Cu+ ions toward the substrate with/without the negative substrate bias voltage.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.2
• /
• pp.105-110
• /
• 2004

The objective of this study is to obtain the instability characteristics of the plane jet impinging on circular cylinder associated with the cylinder-tone. It is found that the characteristics depends upon he ratio of the cylinder diameter to the nozzle width, D/h, and the jet velocity. When the ratio is oderate the cylinder-tone is similar to the edge-tone. With increase of the ratio, its characteristics ecomes similar to that of the plate-tone in which only the high-speed tone associated with turbulent et is generated. When D/h 〈1. the frequency range, especially the lower limit of frequency, is ignificantly influenced by the cylinder diameter. At around D/h = 1/2, while low speed tones are nduced with the antisymmetric mode of instability and affected by the vortex shedding from the ylinder, high-speed tones are generated, at first, with the symmetric mode of instability. and then, ith antisymmetric mode, as the jet velocity increases.

• Journal of Korean Society of Forest Science
• /
• v.113 no.1
• /
• pp.51-65
• /
• 2024

Phyto-sociological methods were used in this study to assess the vegetation structure of a forest stand at Mt. Goehwa in Sejong-Si with the aim of providing vegetation information for urban forest utilization and management plans. The actual forest vegetation was classified into two types of community groups (Quercus serrata-Lindera obtusiloba and Coreopsis lanceolata community groups) at the highest hierarchical level. The Q. serrata-L. obtusiloba community group was classified into six units, which included artificial forest and natural forest vegetation. Artificial forests were classified into three communities (Pinus rigida, Castanea crenata, and Robinia pseudoacacia), whereas natural forests were classified into three communities (Quercus variabilis, Quercus acutissimaa, and Pinus densiflora). The Coreopsis lanceolata community group, which exhibited vegetative characteristics of urban forest edge areas, was categorized into four units. The urban forest edges were classified into four communities (Indigofera bungeana, Lespedeza bicolor, Amorpha fruticosa, and Lespedeza cuneata). Accordingly, the vegetation structure of Mt. Goehwa was categorized into 10 vegetation unit systems. An importance value analysis showed the highest importance value for C. crenata at 6.7%, followed by P. rigida at 6.4%, and R. pseudoacacia at 6.3%, indicating that the ecological impact of plantation species can be significant on Mt. Goehwa. A community coefficient of similarity analysis revealed that the artificial and natural forests had similar species compositions; however, both forests differed from the urban forest edge. This variation was further confirmed by Detrended correspondence analysis(DCA), with similar results. Canonical correspondence analysis(CCA) showed that the artificial forest and natural forest community types were positively correlated with altitude, bare rock, and the present species. By contrast, the urban forest edge community types were negatively correlated with these factors.