• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.554-554
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• 2012

Controlling the size distribution of gold nanoparticles (NPs) is of great importance due to the fact that their properties are strongly dependent upon the size distribution as well as the size itself. In the citrate reduction method for gold NP synthesis, the citrate works as (1) a reducing agent, (2) a surfactant, and also (3) a weak base: it raises the pH of the whole reaction mixture. Here, we have extensively studied the all three roles of the citrate, by adding other reagents separately (NaBH4, CTAB, and NaOH) for the independent control of the three roles of the citrate. Among the roles of the citrate, that as a weak base was found to be the most critical parameter affecting the size distribution of gold NPs and the size distribution became much more improved with the increase of the solution pH, while adding a supplementary surfactant or reducing agent resulted in the formation of less homogeneous NPs.

• The Journal of the Convergence on Culture Technology
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• v.8 no.1
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• pp.545-550
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• 2022

In Deep Learning method, it is well known that it requires large amount of data to train the deep neural network. And it also requires the labeling of each data to fully train the neural network, which means that experts should spend lots of time to provide the labeling. To alleviate the problem of time-consuming labeling process, some methods have been suggested such as weak-supervised method, one-shot learning, self-supervised, suggestive learning, and so on. In this manuscript, those methods are analyzed and its possible future direction of the research is suggested.

• Journal of Internet Computing and Services
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• v.6 no.6
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• pp.187-197
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• 2005

In this paper, we propose a method to estimate camera motion parameter based on invariant point features, Typically, feature information of image has drawbacks, it is variable to camera viewpoint, and therefore information quantity increases after time, The LM(Levenberg-Marquardt) method using nonlinear minimum square evaluation for camera extrinsic parameter estimation also has a weak point, which has different iteration number for approaching the minimal point according to the initial values and convergence time increases if the process run into a local minimum, In order to complement these shortfalls, we, first proposed constructing feature models using invariant vector of geometry, Secondly, we proposed a two-stage calculation method to improve accuracy and convergence by using 2D homography and LM method, In the experiment, we compared and analyzed the proposed method with existing method to demonstrate the superiority of the proposed algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4C
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• pp.411-417
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• 2007

The rate control is an essential component in video coding to provide better quality under given coding constraints, such as channel capacity, frame rates, etc. In general, source data cannot be described as a single distribution in a video coding, hence it can cause an exhaustive approximation problem. It drops a coding efficiency under weak channel environments, such as mobile communications. In this paper, we design a new quantization parameter decision model that is based on a rate-distortion function of generalized Gaussian distribution. In order to adaptively express various source data distribution, we decide a shape parameter by observing a ratio of samples, which have a small value. For experiment, the proposed algorithm is implemented into H.264/AVC video codec, and its performance is compared with that of MPEG-2 TM5, H.263 TMN8 rate control algorithm. As shown in simulation results, the proposed algorithm provides an improved quality rather than previous algorithms and generates the number of bits closed to the target bits.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.33.2-33.2
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• 2010

We have investigated a relationship among the solar proton events (SPEs), coronal mass ejections (CMEs) and solar flares during the solar cycle 23 (1997-2006). Using 63 SPE dataset, we found that SPE rise time, duration time, and decrease times depend on CME speed and SPE peak intensity depends on the CME earthward direction parameter as well as CME speed and x-ray flare intensity. While inspecting the relation between SPE peak intensity and the CME earthward direction parameter, we found that there are two groups: first group consists of large 6 SPEs (> 10,000 pfu at >10 MeV proton channel of GOES satellite) and shows a very good correlation (cc=0.65) between SPE peak intensity and CME earthward direction parameter. The second group has a relatively weak SPE peak intensity and shows poor correlation between SPE peak intensity and the CME earthward direction parameter (cc=0.01). By investigating characteristics of 6 SPEs in the first group, we found that there are special common conditions of the extremely large proton events (group 1); (1) all the SPEs are associated with very fast halo CME (>1400km/s), (2) they are almost located at disk region, (3) they also accompany large flare (>M7), (4) all they are preceded by another wide CMEs, and (5) they all show helmet streamer nearby the main CME. In this presentation, we will give details of the energy spectra of the 6 SPE events from the ERNE/HED aboard the Solar and Heliospheric Observatory (SOHO), and onset time comparison among the SPE, flare, type II burst, and CME.

• Journal of the Korean Society of Radiology
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• v.10 no.7
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• pp.531-537
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• 2016

An experimental study was to use the parameter to determine the MRI artifact of chemical shift that occurs in water and fats. Scanning the image according to the encoding parameter and the bandwidth and change in 1.5T and 3.0T MRI to the SNR, we compared the CNR. In the image was confirmed that the occurrence of artefacts in the chemical shift of the water and oil. 3.0T more image artifacts in the 1.5T was confirmed that the relatively reduced. The width of the bandwidth it could be confirmed that according to the honeycombs artifacts decrease. Therefore, in order to reduce the artifacts in the MRI scan of the chemical shift runners weak field strength, is thought to be appropriate to widen the width of the bandwidth.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.583-590
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• 1993

O-Diethylaminoethyl chitosan containing weak cation exchange group had been synthesized. It was used to separate albumin and lysozyme as stationary phase in liquid chromatography column. The separation of acidic and basic dyes were preliminarily conducted to investigate the effect of polarity parameter of solvents. Based on this result, we investigated various factors on the separation efficiency of chromatography in column. In the case of using water-methanol as cosolvent, the resolution factor depended on the polarity parameter. The best resolution factor was 1.42 for DEAE-chitosan with the degree of substitution of 0.23.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.2
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• pp.141-149
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• 1996

Lateral dispersion parameter(.sigma.$_{y}$) which is an important factor in atmospheric dispersion can be estimated byusing wind direction fluctuation(.sigma.$_{\theta}$). In this paper, we studied the characteristics of the .sigma.$_{\theta}$ in the Chunchon basin and calculated the .sig- ma.$_{y}$ by using the .sigma.$_{\theta}$. We could find some characteristics of the .sigma.$_{\theta}$ which showed small value, when the atmospheric condition was in weak unstable (C class) and neutral (D class). Moreover, when the atmospheric stability was neutral, there was no difference of .sigma.$_{\theta}$ with wind speed. On the other hand, .sigma.$_{\theta}$ showed large values at the strong unstable (A class) and strong stable (F class) condition with low wind speed. In this case, the .sigma.$_{\theta}$ increased as long as averaging time due to the long-period wind direction fluctuation by the terrain effect. In the result of calculation of .sigma.$_{y}$, it was smaller than that of pasquill-Gifford curve. Especially, when the atmospheric condition was in a neutral and stable, .sigma.$_{y}$ showed small increment as the downwind distance increased.creased.

• The Journal of the Acoustical Society of Korea
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• v.22 no.2E
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• pp.69-77
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• 2003

Correlations between acoustic properties and bone density have been investigated in bovine cancellous bone. Speed of sound (SOS), broadband ultrasonic attenuation (BUA), and broadband ultrasonic reflection (BUR) were measured in 10 defatted bovine cancellous bone specimens in vitro. SOS showed a significant correlation with the apparent density of the bone. A comparable correlation was observed between BUA and the apparent density. BUR was rather highly correlated with the apparent density. It was shown that BUR had a weak correlation with BUA and a significant correlation with SOS. This indicates that the parameter BUR can provide important information that may not be contained in BUA and SOS and, therefore, can be useful as an alternative diagnostic parameter of osteoporosis. As expected, a linear combination of all three ultrasonic parameters in a multiple regression model resulted in a significant improvement in predicting the apparent bone density.

• ETRI Journal
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• v.38 no.3
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• pp.568-578
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• 2016

A wireless power transfer (WPT) system is usually classified as being of either a two-coil or four-coil type. It is known that two-coil WPT systems are suitable for short-range transmissions, whereas four-coil WPT systems are suitable for mid-range transmissions. However, this paper reveals that the two aforementioned types of WPT system are alike in terms of their performance and characteristics, differing only when it comes to their matching-network configurations. In this paper, we first find the optimum load and source conditions using Z-parameters. Then, we estimate the maximum power transfer efficiency under the optimum load and source conditions, and we describe how to configure the matching networks pertaining to both types of WPT system for the given optimum load and source conditions. The two types of WPT system show the same performance with respect to the coupling coefficient and load impedance. Further, they also demonstrate an identical performance in the two cases considered in this paper, that is, a strong-coupled case and a weak-coupled case.