• 한국수산과학회지
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• 제41권1호
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• pp.54-60
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• 2008

High- and multi-frequency acoustic systems can measure a zooplankton patch successively and estimate the spatial distribution and abundance of zooplankton according to size using a multi-frequency inversion (MFI) method. This study measured zooplankton distribution to a depth of 150m using a multi-frequency acoustic system (TAPS-6), installed on a CTD system with a fluorometer and analyzed it using the MFI method. Simultaneously, zooplankton samples were collected by north pacific standard (NORPAC) net to confirm the species composition. The results showed that the combined method is valuable for estimating the zooplankton profile in detail and investigating the relationship between the zooplankton and phytoplankton profiles.

• Wind and Structures
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• 제20권5호
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• pp.661-682
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• 2015

This study investigates the use of time-frequency coherence analysis for detecting and evaluating coherent "structures" of surface pressures and wind turbulence components, simultaneously on the time-frequency plane. The continuous wavelet transform-based coherence is employed in this time-frequency examination since it enables multi-resolution analysis of non-stationary signals. The wavelet coherence quantity is used to identify highly coherent "events" and the "coherent structure" of both wind turbulence components and surface pressures on rectangular prisms, which are measured experimentally. The study also examines, by proposing a "modified" complex Morlet wavelet function, the influence of the time-frequency resolution and wavelet parameters (i.e., central frequency and bandwidth) on the wavelet coherence of the surface pressures. It is found that the time-frequency resolution may significantly affect the accuracy of the time-frequency coherence; the selection of the central frequency in the modified complex Morlet wavelet is the key parameter for the time-frequency resolution analysis. Furthermore, the concepts of time-averaged wavelet coherence and wavelet coherence ridge are used to better investigate the time-frequency coherence, the coherently dominant events and the time-varying coherence distribution. Experimental data derived from physical measurements of turbulent flow and surface pressures on rectangular prisms with slenderness ratios B/D=1:1 and B/D=5:1, are analyzed.

• 물과 미래
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• 제10권1호
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• pp.101-117
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• 1977

The statatistical characteristics and spectra of sea waves at Mookho were analysed by several statistical methods. As the results, the following conclusions are obtained: 1. Values of surface elevation of sea wave are better fitted to Gram Charlier distribution than Gaussian distribution. This proves that sea waves have not only characters of irregularity but also non-linearity. 2. Distribution of maxima of surface elevation practically follows the distribution of Cartwright and Longuet-Higgins, also spectral width parameter is found to be increased with the increase of root mean square of surface elevation. 3. Sea wave may have spectrum of broad frequency band, however distributions of wave heights and periods follow the Rayleigh distribution which is derived from the assumption of narrow frequency band. 4. Ratios among mean wave heights from observed data show good agreements with theoretical values from Rayleigh distribution. 5. Spectral density and spectral width parameter increase with increase of wind velocity. And wave period at optimum band gas higher value than significant wave period by about 10 percent.

• 대한수의학회지
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• 제6권1호
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• pp.82-91
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• 1966

Studies On the myelinated fibers of the recurrent laryneal nerves were made in five, species of domestic animals namely dog, pig, goat, horse and Korean ox. Throughout the studies, the following characteristics of the myelinated fibers were obtained. 1. The number, size and cross sectional area of the myelinated fibers seemed to be proportionally related to the animal body weights. 2. The highest peak of diameter size frequency distribution of the myelinated fibers, observed at the right cranial level, in dog, goat and horse were 4-6 micron group, while in the case of Korean ox, 10-12 micron group was the highest. 3. The highest peak of diameter size frequency distribution of the myelinated fibers, observed at the right caudal level of Korean ox was 6-8 micron group, and 4-6 micron group was the highest in the other animals. 4. The highest peak of diameter size frequency distribution of the myelinated fibers obsered at the left cranial level was same to that of right cranial level. 5. The highest peak of diameter size frequency distribution of the myelinated fibers, observed at the left caudal levels in dog, goat, horse and Korean ox was 4-6 micron group, while in case of pig, $14-16{\mu}$ group was the highest. 6. The largest cross sectional areas were found in the group of 10-16 micron in all species of animals. 7. The fiber diameter size frequency distribution of recurrent laryngeal nerves of dog, goat, pig and horse were bimodal and Korean ox seemed to be a unimodal.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1803-1805
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• 1998

Electron temperature, electron density and electron energy distribution function were measured in Radio-Frequency Inductively Coupled Plasma(RFICP) using a probe method. Measurements were conducted in argon discharge for pressure from 10 mTorr to 40 mTorr and input rf power from 100W to 600W and flow rate from 3 sccm to 12 sccm. Spatial distribution electron temperature and electron density and electron energy distribution function were measured for discharge with same aspect ratio(R/L=2). Electron temperature was found to depend on pressure, but only weakly on power. Electron density and electron energy distribution function strongly depended on both pressure and power. Electron density and electron energy distribution function increased with increasing flow rate. Radial distribution of the electron density and electron energy distribution function were peaked in the plasma center. Normal distribution of the electron density electron energy distribution function were peaked in the center between quartz plate and substrate. These results were compared to a simple model of ICP, then we found out the generation mechanism of Radio-Frequency Inductively Coupled Plasma.

• 조명전기설비학회논문지
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• 제13권4호
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• pp.82-86
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• 1999

본 연구에서는 푸로브법과 교류중첩법을 이용하여 고주파 유도결합 플라즈마에서 전자에너지 분포함수를 측정하였다. 실험조건은 압력 10∼40[mTorr], 입력파워는 100∼600[W]이고, 가스유량은 3∼12[sccm]이며, 전자에너지 분포함수의 공간분포 측정에 있어서 아스펙트비(R/L)는 2로 하였다. 전자에너지 분포함수는 압력 및 입력파워에 대하여 강한 의존성을 나타내었고, 가스유량이 증가할수록 증가 하였다. 전자에너지 분포함수의 반경방향 분포는 플라즈마 중심에서 최대가 되었다. 전자에너지 분포함수의 축방향 분포는 석영창과 기판 사이의 중심에서 최대가 되었다. 이러한 결과는 고주파 유도결합 플라즈마의 생성 메커니즘 이해와 간단한 ICP(Inductively Coupled Plasma) 모델링 응용에 기여할 수 있을 것이다.

• 유통과학연구
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• 제15권10호
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• pp.41-50
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• 2017

Purpose - Online product review has become a crucial part of the online retailer's market performance for a wide range of products. This research aims to investigate how an individual reviewer's review frequency and timing affect her/his average attitude toward products. Research design, data, and methodology - To conduct reviewer-level analysis, this study uses 42,172 posted online review messages generated by 6,941 identified reviewers for 59 movies released in the South Korea from July 2015 to December 2015. This study adopts Tobit model specification to take into account the censored nature and the selection bias arising from the nature of J-shaped distribution of movie rating. Results - Our estimation results support that the negative impact of review frequency and timing on valence. Furthermore, review timing has an inverted-U relationship with the user's average valence and enhance the negative effect of review frequency. Conclusions - This study contributes to the growing literature on the understanding how eWOM is generated at the individual consumer level. On the basis of the main empirical findings, this study provides insights into building a recommendation system in online retail store based on the consumer's review history data - frequency, timing, and valence.

• 한국습지학회지
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• 제10권2호
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• pp.143-153
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• 2008

본 논문의 목적은 ENSO의 영향에 의한 우리나라 강우의 확률빈도와 공간분포 특성을 분석하는 것이다. 따라서 우리나라 기상관측소의 강우량 자료를 Warm(El Nino), Cold(La Nina), Normal 에피소드에 따라 기간별로 분류하였다. 또한 이렇게 분류한 자료는 Markov Chain 모형을 이용하여 100년의 자료로 모의 발생하였고 에피소드별로 빈도분석을 실시하였다. 빈도분석 결과 에피소드에 따라 각 기상관측소별로 강우의 크기에 영향을 미치고 있음을 알 수 있었다. 또한 군집분석을 실시하여 각 에피소드의 공간적인 영향에 대해서 분석하였다. 결과적으로 Warm(El Nino), Cold(La Nina) and Normal 에피소드로 대표되는 ENSO는 우리나라 강우의 확률빈도과 공간분포에 크게 영향을 미치는 것으로 파악되었다.

• Computers and Concrete
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• 제25권3호
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• pp.215-224
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• 2020

In the present study, according to the important of porosity in low specific weight in comparison of high stiffness of carbon nanotubes reinforced composite, buckling and free vibration analysis of sandwich composite beam in two configurations, of laminates using differential quadrature method (DQM) is studied. Also, the effects of porosity coefficient and three types of porosity distribution on critical buckling load and natural frequency are discussed. It is shown the buckling loads and natural frequencies of laminate 1 are significantly larger than the results of laminate 2. When configuration 2 (the core is made of FRC) and laminate 1 ([0/90/0/45/90]_s) are used, the first natural frequency rises noticeably. It is also demonstrated that the influence of the core height in the case of lower carbon volume fractions is negligible. Even though, when volume fraction of fiber increases, the critical buckling load enhances smoothly. It should be noticed the amount of decline has inverse relationship with the beam aspect ratio. Investigating three porosity patterns, beam with the distribution of porosity Type 2 has the maximum critical buckling load and first natural frequency. Among three elastic foundations (constant, linear and parabolic), buckling load and natural frequency in linear variation has the least amount. For all kind of elastic foundations, when the porosity coefficient increases, critical buckling load and natural frequency decline significantly.

• 산경연구논집
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• 제10권8호
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• pp.17-24
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• 2019

Purpose - The purpose of this study is to find out research directions for distribution and fusion and complex field to many domestic and foreign researchers carrying out related academic research by confirming research trends in the Journal of Distribution Science (JDS). Research Design, Data, and Methodology - To do this, I used keywords from a total of 904 papers published in the JDS excluding 19 papers that were not presented with keywords among 923. The analysis utilized word clouding, topic modeling, and weighted frequency analysis using the R program. Results - As a result of word clouding analysis, customer satisfaction was the most utilized keyword. Topic modeling results were divided into ten topics such as distribution channels, communication, supply chain, brand, business, customer, comparative study, performance, KODISA journal, and trade. It is confirmed that only the service quality part is increased in the weighted frequency analysis result of applying to the year group. Conclusion - The results of this study confirm that the JDS has developed into various convergence and integration researches from the past studies limited to the field of distribution. However, JDS's identity is based on distribution. Therefore, it is also necessary to establish identity continuously through special editions of fields related to distribution.