38 research outputs found
๋์ผ ํฝ์ ์ด๋ฏธ์ง ๊ธฐ๋ฐ ์ ๋ก์ท ๋ํฌ์ปค์ค ๋๋ธ๋ฌ๋ง
ํ์๋
ผ๋ฌธ(์์ฌ) -- ์์ธ๋ํ๊ต๋ํ์ : ๊ณต๊ณผ๋ํ ํ๋๊ณผ์ ์ธ๊ณต์ง๋ฅ์ ๊ณต, 2022. 8. ํ๋ณดํ.Defocus deblurring in dual-pixel (DP) images is a challenging problem due to diverse camera optics and scene structures. Most of the existing algorithms rely on supervised learning approaches trained on the Canon DSLR dataset but often suffer from weak generalizability to out-of-distribution images including the ones captured by smartphones. We propose a novel zero-shot defocus deblurring algorithm, which only requires a pair of DP images without any training data and a pre-calibrated ground-truth blur kernel. Specifically, our approach first initializes a sharp latent map using a parametric blur kernel with a symmetry constraint. It then uses a convolutional neural network (CNN) to estimate the defocus map that best describes the observed DP image. Finally, it employs a generative model to learn scene-specific non-uniform blur kernels to compute the final enhanced images. We demonstrate that the proposed unsupervised technique outperforms the counterparts based on supervised learning when training and testing run in different datasets. We also present that our model achieves competitive accuracy when tested on in-distribution data.๋์ผ ํฝ์
(DP) ์ด๋ฏธ์ง ์ผ์๋ฅผ ์ฌ์ฉํ๋ ์ค๋งํธํฐ์์์ Defocus Blur ํ์์ ๋ค์ํ ์นด๋ฉ๋ผ ๊ดํ ๊ตฌ์กฐ์ ๋ฌผ์ฒด์ ๊น์ด ๋ง๋ค ๋ค๋ฅธ ํ๋ฆฟํจ ์ ๋๋ก ์ธํด ์ ์์ ๋ณต์์ด ์ฝ์ง ์์ต๋๋ค. ๊ธฐ์กด ์๊ณ ๋ฆฌ์ฆ๋ค์ ๋ชจ๋ Canon DSLR ๋ฐ์ดํฐ์์ ํ๋ จ๋ ์ง๋ ํ์ต ์ ๊ทผ ๋ฐฉ์์ ์์กดํ์ฌ ์ค๋งํธํฐ์ผ๋ก ์ดฌ์๋ ์ฌ์ง์์๋ ์ ์ผ๋ฐํ๊ฐ ๋์ง ์์ต๋๋ค. ๋ณธ ๋
ผ๋ฌธ์์๋ ํ๋ จ ๋ฐ์ดํฐ์ ์ฌ์ ๋ณด์ ๋ ์ค์ Blur ์ปค๋ ์์ด๋, ํ ์์ DP ์ฌ์ง๋ง์ผ๋ก๋ ํ์ต์ด ๊ฐ๋ฅํ Zero-shot Defocus Deblurring ์๊ณ ๋ฆฌ์ฆ์ ์ ์ํฉ๋๋ค. ํนํ, ๋ณธ ๋
ผ๋ฌธ์์๋ ๋์นญ์ ์ผ๋ก ๋ชจ๋ธ๋ง ๋ Blur Kernel์ ์ฌ์ฉํ์ฌ ์ด๊ธฐ ์์์ ๋ณต์ํ๋ฉฐ, ์ดํ CNN(Convolutional Neural Network)์ ์ฌ์ฉํ์ฌ ๊ด์ฐฐ๋ DP ์ด๋ฏธ์ง๋ฅผ ๊ฐ์ฅ ์ ์ค๋ช
ํ๋ Defocus Map์ ์ถ์ ํฉ๋๋ค. ๋ง์ง๋ง์ผ๋ก CNN์ ์ฌ์ฉํ์ฌ ์ฅ๋ฉด ๋ณ Non-uniformํ Blur Kernel์ ํ์ตํ์ฌ ์ต์ข
๋ณต์ ์์์ ์ฑ๋ฅ์ ๊ฐ์ ํฉ๋๋ค. ํ์ต๊ณผ ์ถ๋ก ์ด ๋ค๋ฅธ ๋ฐ์ดํฐ ์ธํธ์์ ์คํ๋ ๋, ์ ์๋ ๋ฐฉ๋ฒ์ ๋น์ง๋ ๊ธฐ์ ์์๋ ๋ถ๊ตฌํ๊ณ ์ต๊ทผ์ ๋ฐํ๋ ์ง๋ ํ์ต์ ๊ธฐ๋ฐ์ ๋ฐฉ๋ฒ๋ค๋ณด๋ค ์ฐ์ํ ์ฑ๋ฅ์ ๋ณด์ฌ์ค๋๋ค. ๋ํ ํ์ต ๋ ๊ฒ๊ณผ ๊ฐ์ ๋ถํฌ ๋ด ๋ฐ์ดํฐ์์ ์ถ๋ก ํ ๋๋ ์ง๋ ํ์ต ๊ธฐ๋ฐ์ ๋ฐฉ๋ฒ๋ค๊ณผ ์ ๋์ ๋๋ ์ ์ฑ์ ์ผ๋ก ๋น์ทํ ์ฑ๋ฅ์ ๋ณด์ด๋ ๊ฒ์ ํ์ธํ ์ ์์์ต๋๋ค.1. Introduction 6
1.1. Background 6
1.2. Overview 9
1.3. Contribution 11
2. Related Works 12
2.1.Defocus Deblurring 12
2.2.Defocus Map 13
2.3.Multiplane Image Representation 14
2.4.DP Blur Kernel 14
3. Proposed Methods 16
3.1. Latent Map Initialization 17
3.2. Defocus Map Estimation 20
3.3. Learning Blur Kernel s 22
3.4. Implementation Details 25
4. Experiments 28
4.1. Dataset 28
4.2. Quantitative Results 29
4.3. Qualitative Results 31
5. Conclusions 37
5.1.Summary 37
5.2. Discussion 38์
Synthesis and Properties of Strontium W-type Hexagonal Ferrite
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ผ๋ฌธ (์์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ์ฌ๋ฃ๊ณตํ๋ถ, 2014. 2. ์ ์์.๋ณธ ์ฐ๊ตฌ์์๋ ๊ณต๊ธฐ ์ค ๊ณ ์จ์์ญ์์๋ง ์์ ํ๊ธฐ ๋๋ฌธ์ ์์จ์์ ๋จ์ผ์์ ์ป๊ธฐ๊ฐ ํ๋ค๋ค๊ณ ์๋ ค์ง ์คํธ๋ก ํฌ W-type ์ก๋ฐฉ์ ํ๋ผ์ดํธ(SrFe18O27SrW)์ ๋จ์ผ์์ ํฉ์ฑํ๊ณ , ๊ทธ ๋ฌผ์ฑ์ ๊ท๋ช
ํ๊ณ ์ ํ์๋ค. ์ํธ์ ๊ณ ์๋ฐ์๋ฒ์ผ๋ก ์ ์กฐ ํ์์ผ๋ฉฐ, SrCO3์ Fe2O3๋ฅผ 1:9์ ๋น์จ๋ก ์์ ๋ถ๋ง์ ๊ณต๊ธฐ ์ค 1150โ์์ 8์๊ฐ์ 1์ฐจ ํ์๋ฅผ ํ ํ, ๊ณต๊ธฐ ์ค, N2๊ฐ์ค ๋ถ์๊ธฐ(PO2 = 5 ร 10-8 atm) ๊ทธ๋ฆฌ๊ณ 1000ppm์ ์ฐ์๋๋๋ฅผ ๊ฐ๋ O2/N2ํผํฉ๊ฐ์ค ๋ถ์๊ธฐ(PO2 = 10-3 atm)์ค ๊ณ ์จ์์ญ์์ ๊ฐ๊ฐ 2์๊ฐ ๋์ ์ด์ฒ๋ฆฌ ํ ๋ก๋ํ์๋ค.
๊ณต๊ธฐ ์ค ์ด์ฒ๋ฆฌ ํ ๋ก๋์์๋ ๋๊ฐ ๊ณผ์ ์ค ์ผ์ด๋๋ ์๋ถํด๋ก ์ธํด ์์จ์์ SrW์ ๋จ์ผ์์ ์ป์ ์๊ฐ ์์๊ณ , ์คํธ๋ก ํฌ M-type ์ก๋ฐฉ์ ํ๋ผ์ดํธ(SrFe12O19SrM)์ Fe2O3๊ฐ ํจ๊ป ์กด์ฌํ๋ ํผํฉ์์ด ๋ํ๋ฌ๋ค. ๊ณต๊ธฐ ์ค 1400โ์์ ์ด์ฒ๋ฆฌํ ํ ์๋ํ ๊ฒฝ์ฐ ๋จ์ผ์์ ์ป์ ์ ์์์ผ๋ ์ด ์ถฉ๊ฒฉ์ผ๋ก ์ธํด ์ํธ์ด ๋ถ์์ง๋ ํ์์ ๋ง์ ์ ์์๋ค.
0.05ppm์ ์ฐ์๋๋๋ฅผ ๊ฐ๋ N2๊ฐ์ค(PO2 = 5 ร 10-8 atm)๋ฅผ ์ฌ์ฉํ์ฌ ์ด์ฒ๋ฆฌํ ๊ฒฝ์ฐ 1275, 1300โ์ ์จ๋์์ SrW์ ์์ด ํฉ์ฑ๋์์ง๋ง ์๋์ Fe3O4๊ฐ ์ด์ฐจ์์ผ๋ก ๋ฐ๊ฒฌ๋์๋ค. 1325โ์ด์์ ์จ๋์์ ์ด์ฒ๋ฆฌํ์์ ๋๋ Fe3O4์ ์ก์์์ ์๊ณ ๋ ๋ค๋ฅธ ์๋ค์ด ๋ฐ๊ฒฌ๋์์ผ๋ฉฐ, 1250โ์์ ์ด์ฒ๋ฆฌํ์์ ๋๋ SrW์ ์์ด ํฉ์ฑ๋์ง ์๊ณ SrM๊ณผ Fe3O4์ ์์ด ํฉ์ฑ ๋ ๊ฒ์ ํ์ธํ์๋ค.
1000ppm์ ์ฐ์๋๋๋ฅผ ๊ฐ๋ O2/N2ํผํฉ๊ฐ์ค(PO2 = 10-3 atm)๋ฅผ ์ฌ์ฉํ์ฌ ์ด์ฒ๋ฆฌํ ๊ฒฐ๊ณผ 1300โ1350โ์ ์จ๋์์ญ์์ SrW๋ฅผ ํฉ์ฑํ ํ ๋ก๋ํ์ฌ ์๋ถํด ์์ด ๋จ์ผ์์ ์ป์ ์ ์์๋ค. 1275โ์์ ์ด์ฒ๋ฆฌํ์์ ๋๋ ์๋์ SrM๊ณผ Fe2O3์ ์ด์ฐจ์์ด ๋ฐ๊ฒฌ๋์๊ณ , 1250โ์์ ์ด์ฒ๋ฆฌํ์์ ๋๋ SrW์ ์์ด ํฉ์ฑ๋์ง ์๊ณ SrM๊ณผ Fe2O3์ ์์ด ๋ฐ๊ฒฌ๋์๋ค. ์ด์ฒ๋ฆฌ์จ๋๋ฅผ 1375 โ๊น์ง ์์น์์ผฐ์ ๋๋ Fe3O4์ ์ก์์์ ์๊ณ ๋ ๋ค๋ฅธ ์๋ค์ด ๋ํ๋ฌ๋ค. SrW์ ์ ์์ ์์ญ์ ์ข ๋ ์ ํํ๊ฒ ๊ฒฐ์ ํ๊ธฐ ์ํ์ฌ 1275-1300 โ์ ์จ๋๊ตฌ๊ฐ๊ณผ 1350-1375 โ์ ์จ๋๊ตฌ๊ฐ์์ ์ถ๊ฐ ์คํ์ ์งํํ ๊ฒฐ๊ณผ 1000ppm์ ์ฐ์ ๋ถ์(PO2 = 10-3 atm)์์์ SrW์ ์ ์์ ์จ๋์์ญ์ 1297.5 ยฑ 2.5โ ์ด์ 1352.5 ยฑ 2.5โ์ดํ์์ ๊ท๋ช
ํ ์ ์์๋ค.
๊ณต๊ธฐ ์ค 1์ฐจ ํ์ ํ O2/N2ํผํฉ๊ฐ์ค ๋ถ์๊ธฐ์ค 1300, 1325, 1350โ์์ ์ด์ฒ๋ฆฌํ ์ํธ๋ค์ ๊ฐ๊ฐ 71.5, 73.9, 72.1 emu/g์ Ms๊ฐ๊ณผ 79.4, 82.7 91.7%์ ๋ค์ ๋ฎ์ ์๋ ๋ฐ๋๋ฅผ ๋ณด์์ผ๋ฉฐ, O2/N2ํผํฉ๊ฐ์ค ๋ถ์๊ธฐ(PO2 = 10-3 atm)์ค 1300โ๋ฅผ 2์ฐจ ํ์ ์จ๋๋ก ์ ํ๊ณ 2์ฐจ ํ์๋ฅผ ๊ฑฐ์น ๋ถ๋ง์ 1300, 1325, 1350โ์ ์จ๋์์ ์๊ฒฐ ์ด์ฒ๋ฆฌํ ์ํธ์ ๊ฒฝ์ฐ ๊ฐ๊ฐ 70.8, 72.8, 72.4 emu/g์ Ms๊ฐ๊ณผ 79.2, 85.0, 93.6%์ ์ฌ์ ํ ๋ฎ์ ์๋ ๋ฐ๋๋ฅผ ๋ํ๋ด๋ ๊ฒ์ ํ์ธํ์๋ค. ์ด๋ฌํ ๋ฎ์ ์๋๋ฐ๋์ ์์ธ์ ์ํธ์ ๋ค์ ์กด์ฌํ๋ ๊ธฐ๊ณต ๋๋ฌธ์ด๋ฉฐ ์ด๋ ์น์จ๊ณผ์ ์ค ๋น ๋ฅธ ์๋๋ก ์์ ๋ถํด๊ฐ ์ผ์ด๋ฌ๋ค๊ฐ ๋ค์ ํฉ์ฑ๋๋ ๊ณผ์ ๋๋ฌธ์ ๋ฐ์ํ ๊ฒ์ผ๋ก ์ฌ๋ฃ๋๋ค.
๊ฒฐ๋ก ์ ์ผ๋ก ๊ณต๊ธฐ ์ค ๋ก๋์ผ๋ก ์์จ์์ ์ป๊ธฐ๊ฐ ํ๋ SrW์ ๋จ์ผ์์ 1000ppm(PO2 = 10-3 atm)๊ณผ ๊ฐ์ ๋ฎ์ ์ฐ์๋ถ์์์ ํฉ์ฑํ๊ณ ๊ทธ ๋ถ์๊ธฐ์์ ๋ก๋์ ํตํด XRD์์ผ๋ก ์์จ์์ ๋จ์ผ์์ ์ป์ ์ ์์๋ค. ๋ํ ์ด๋ฌํ ๋ฎ์ ์ฐ์๋ถ์์์ SrW์ ์ ์์ ์์ญ์ ์คํ์ ์ผ๋ก ์ ํํ ๊ท๋ช
ํ์๋๋ฐ, ์ด ๊ฒฐ๊ณผ๋ก๋ถํฐ SrW์ ์ ์์ ์์ญ์ด ๊ณต๊ธฐ ์ค๋ณด๋ค ๋ฎ์ ์จ๋ ์์ญ์ผ๋ก ์ด๋ํ๋ค๋ ๊ฒ๊ณผ ๊ณต๊ธฐ ์ค ๋ก๋์์ ๋ฐ์ํ๋ ์๋ถํด๋ฅผ ๋ฎ์ ์ฐ์๋ถ์์์ ๋ก๋์ ์ต์ ํ ์ ์์๋ค.In this study, we tried to synthesize the single phase of strontium W-type hexagonal ferrite(SrFe18O27SrW) which is known difficult to obtain a single phase at room temperature because it is stable only at high temperature region of 1350-1440 โ in air, and also to identify its physical properties. The samples were prepared by the standard solid state reaction. The powder of SrCO3 and Fe2O3 were mixed together with a ratio of 1 : 9, and then calcined at 1150 โ for 8 h in air. As-calcined powder was pressed into pellets, and then annealed at various high temperatures for 2 h in air, N2(PO2 = 5 ร 10-8 atm), and O2/N2(PO2 = 10-3 atm) atmosphere, respectively.
When the samples were annealed in air, the SrW single phase was not obtained due to the phase decomposition during furnace-cooling. Instead, the mixed phases of strontium M-type hexagonal ferrite(SrFe12O19SrM) and Fe2O3 were obtained. When the sample was water-quenched after annealing at 1400 โ in air for 2 h, while the SrW single phase could be obtained, the sample was broken due to a thermal shock.
The samples annealed at 1275 and 1300 โ in N2 atmosphere(PO2 = 5 ร 10-8 atm) by using N2 gas having an oxygen concentration of 0.05 ppm, consisted of SrW with a small amount of Fe3O4. When samples were annealed at 1325 โ, Fe3O4 and other phases solidified from a liquid phase were found, and SrM and Fe3O4 were detected for the samples annealed at the temperatures below 1250 โ.
The single phase of SrW could be obtained by annealing at the temperature region of 1300-1350 โ in O2/N2 atmosphere(PO2 = 10-3 atm) and then followed by furnace-cooling without phase decomposition. When the sample was annealed at 1275 โ, small amount of SrM and Fe2O3 were found as second phases. When the annealing temperature was increased up to 1375 โ, Fe3O4 and other phases solidified from a liquid phase were found. In order to determine the phase stability region of SrW in PO2 = 10-3 atm more accurately, annealing was performed at the temperature region of 1275-1300 โ and 1350-1375 โ. We determined the stability temperature region of SrW in PO2 = 10-3 atm as 1352.5 ยฑ 2.5 โ - 1297.5 ยฑ 2.5 โ.
The samples annealed in O2/N2 atmosphere after calcination in air, showed Ms values of 71.5, 73.9, 72.1 emu/g and rather low relative densities of 79.4, 82.7 91.7%, respectively. To improve the relative density, secondary calcination was performed at 1300 โ for 2 h in O2/N2 atmosphere, and followed by sintering at the temperature region of 1300, 1325, 1350 โ in PO2 = 10-3 atm. The samples showed Ms values of 70.8, 72.4, 72.8 emu/g and still low relative densities of 79.2, 85.0, 93.6%, respectively. The cause of such a low relative density is pores present in the sample which might be attributed to the phase decomposition during the heating process.
As a result, we could obtain a single phase of SrW at room temperature by annealing followed by furnace-cooling in low oxygen pressure, such as 1000 ppm(PO2 = 10-3 atm). Furthermore, we determined the phase stability temperature region of SrW in PO2 = 10-3 atm, and from this result, it was confirmed that the phase stability temperature region was shifted to lower temperature when compared to that of in air. And also we could inhibit the phase decomposition of SrW during the furnace-cooling.1. ์๋ก 5
2. ๋ฌธํ์ฐ๊ตฌ 6
2.1. ์ก๋ฐฉ์ ํ๋ผ์ดํธ 7
2.1.1. ์ก๋ฐฉ์ ํ๋ผ์ดํธ์ ์ข
๋ฅ์ ํน์ฑ 7
2.1.2. W-type ์ก๋ฐฉ์ ํ๋ผ์ดํธ์ ํน์ฑ 11
2.2. ์ก๋ฐฉ์ ํ๋ผ์ดํธ์ ํฉ์ฑ ๋ฐฉ๋ฒ 15
3. ์คํ ๋ฐฉ๋ฒ 16
3.1. ์คํธ๋ก ํฌ W-type ์ก๋ฐฉ์ ํ๋ผ์ดํธ์ ํฉ์ฑ 16
3.1.1. ์คํธ๋ก ํฌ W-type ์ก๋ฐฉ์ ํ๋ผ์ดํธ์ ์ ์กฐ๊ณต์ 16
3.2. ์คํธ๋ก ํฌ W-type ์ก๋ฐฉ์ ํ๋ผ์ดํธ์ ํน์ฑ ๋ถ์ 17
3.2.1. ๊ฒฐ์ ๊ตฌ์กฐ์ ์ ๋ถ์ 17
3.2.2. ๋ฏธ์ธ์กฐ์ง ๊ด์ฐฐ 17
3.2.3. ์๊ฒฐ๋ฐ๋ ์ธก์ 17
3.2.4. ์๊ธฐ์ ํน์ฑ 18
4. ์คํ ๊ฒฐ๊ณผ ๋ฐ ๊ณ ์ฐฐ 19
4.1. ์ ํฉ์ฑ ๋ฐ ํน์ฑ ํ๊ฐ 19
4.1.1. ๊ณต๊ธฐ ์ค ํ์ ํ ๊ณต๊ธฐ ์ค์์์ ์ ํฉ์ฑ 19
4.1.2. ๊ณต๊ธฐ ์ค ํ์ ํ N2๊ฐ์ค ๋ถ์๊ธฐ์์์ ์ ํฉ์ฑ 24
4.1.3. ๊ณต๊ธฐ ์ค ํ์ ํ O2/N2ํผํฉ๊ฐ์ค ๋ถ์๊ธฐ์์์
์ ํฉ์ฑ ๋ฐ ํน์ฑ 28
4.1.4. O2/N2ํผํฉ๊ฐ์ค ๋ถ์๊ธฐ์์ ํ์ ํ
O2/N2ํผํฉ๊ฐ์ค ๋ถ์๊ธฐ์์์ ์ ํฉ์ฑ ๋ฐ ํน์ฑ 45
5. ๊ฒฐ๋ก 52
6. ์ฐธ๊ณ ๋ฌธํ 54
Abstract 58Maste
Breeding for resistance to tobacco mosaic virus in chili pepper(capsicum annuum L.)
ํ์๋
ผ๋ฌธ(๋ฐ์ฌ)--์์ธ๋ํ๊ต ๋ํ์ :๋ํ๊ณผ ์๋ฌผ์ ์ ์ก์ข
ํ ์ ๊ณต ,2003.Docto
Zn์นํ๋ W, Y-ํ์ ํฅ์ฌํ๋ผ์ดํธ์ ์๊ธฐ์ ํน์ฑ ๋ฐ ๋ง์ดํฌ๋กํ ํก์ ํน์ฑ
ํ์๋
ผ๋ฌธ (๋ฐ์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ๊ณต๊ณผ๋ํ ์ฌ๋ฃ๊ณตํ๋ถ, 2019. 2. ์ ์์.์ ๋ณด ํต์ ๊ธฐ์ ์ ๋ฐ๋ฌ๋ก ๊ณ ์ฑ๋ฅ ํด๋ ์ ํ, ๊ฐ์ ์ ํ ๋ฐ ์ฒจ๋จ ์ ์๊ธฐ๊ธฐ์ ์ฌ์ฉ์ด ์ฆ๊ฐํ๊ณ ์๋ค. ๊ทธ๋ฌ๋ ์ ์๊ธฐ๊ธฐ์ ํฌ๊ธฐ๊ฐ ์์์ง๊ณ ์๋ ์ฃผํ์๊ฐ ์ ์ ์ฆ๊ฐํจ์ ๋ฐ๋ผ ์ ์๊ธฐ๊ธฐ์ ์ํด ๋ฐฉ์ถ๋๋ ์ ์๊ธฐํ๊ฐ ์ธ์ ํ ์ ์๊ธฐ๊ธฐ์ ๋์์ ๋ฐฉํดํ์ฌ ์ค์๋์ ์ผ์ผํฌ ์ ์๋ ์ ์๊ธฐ ์ฅํด(EMI)๊ฐ ์ฌ๊ฐํ ๋ฌธ์ ๋ก ๋๋๋๊ณ ์๋ค. ๋ฐ๋ผ์ ์ด๋ฌํ EMI ๋ฌธ์ ๋ฅผ ํด๊ฒฐํ๊ธฐ ์ํด ์
์ฌ ์ ์ํ๋ฅผ ์ฐจํํ๊ณ ์ ์๊ธฐ๊ธฐ๋ฅผ ๋ณดํธํ๋ ์ ์ํ ์ฐจํ ๊ธฐ์ ์ ์ฐ์
์ ์์๊ฐ ์ปค์ง๊ณ ์๋ค. ์ ์ํ ์ฐจํ ๊ธฐ์ ์ค์์๋ ๋ถํ์ํ ์
์ฌ ์ ์๊ธฐํ, ํนํ GHz ๋์ญ์ ์ฃผํ์๋ฅผ ๊ฐ๋ ๋ง์ดํฌ๋กํ๋ฅผ ํก์ ๋๋ ๊ฐ์ ์ํค๋ ์ ์๊ธฐํ ํก์ ๊ธฐ์ ์ด ๋ง์ ์ฐ๊ตฌ์๋ค์ ๊ด์ฌ์ ๋๊ณ ์๋ค.
๋ง์ดํฌ๋กํ ํก์์ฒด์ ๋ง์ดํฌ๋กํ ํก์ ํน์ฑ์ ์ฃผ๋ก ํก์ ๋ฌผ์ง์ ๋ณต์ ํฌ์์จ (ฮผr = ฮผสน โ jฮผสนสน) ๋ฐ ์ ์ ์จ (ฮตr = ฮตสน โ jฮตสนสน)์ ์ํด ๊ฒฐ์ ๋๊ธฐ ๋๋ฌธ์ ๋ค์ํ ์ ์ ์ฒด ๋ฐ ์์ฑ์ฒด๊ฐ ๋ง์ดํฌ๋กํ ํก์์ฒด ์์ฉ์ ์ํด ๊ด๋ฒ์ํ๊ฒ ์ฐ๊ตฌ๋์ด์๋ค. ๋ค์ํ ๋ง์ดํฌ๋กํ ํก์ ์ฌ๋ฃ ํ๋ณด๊ตฐ ์ค์์ ๊ฐ์์ฑ ์ฐํ๋ฌผ ์์ฑ์ฒด์ธ ํฅ์ฌํ๋ผ์ดํธ๋ GHz ์ฃผํ์ ์์ญ์์ ์ ๋นํ ฮผr ๋ฐ ฮตr ๊ฐ์ ๋ํ๋ผ ๋ฟ๋ง ์๋๋ผ ๋ฐ์ด๋ ํํ์ ์์ ์ฑ ๋ฐ ๋ฎ์ ์์ฐ ๋น์ฉ ๋์ ์ ๋งํ ๋ง์ดํฌ๋กํ ํก์ ์ฌ๋ฃ๋ค. ๋ฐ๋ผ์ ๋ณธ ์ฐ๊ตฌ์์๋ ์๋ก์ด ํํ ์กฐ์ฑ์ ๊ฐ๋ W ๋ฐ Y-ํ์
ํฅ์ฌํ๋ผ์ดํธ๋ฅผ ํฉ์ฑํ๊ณ ๋ง์ดํฌ๋กํ ํก์ ํน์ฑ์ ์ต์ด๋ก ์ดํด๋ณด์๋ค. ์ด๋ฅผ ์ํด ๋ฎ์ ์ฐ์ ์๋ ฅ (PO2)์์์ ์๊ฒฐ ์ด์ฒ๋ฆฌ๋ฅผ ํตํด Fe2+์ด์จ ์๋ฆฌ๋ฅผ Zn2+์ด์จ์ด ๋ถ๋ถ์ ์ผ๋ก ์นํํ ํํ์ W ๋ฐ Y-ํ์
ํฅ์ฌํ๋ผ์ดํธ๋ฅผ ํฉ์ฑํ๊ณ ์ ํ๋ค. ๋ํ ๊ทธ๋ค์ ์ ์์ ์ฑ, ์๊ธฐ์ ํน์ฑ ๋ฐ ๋ง์ดํฌ๋กํ ํก์ ํน์ฑ์ ์ดํด๋ณด์์ผ๋ฉฐ ์ฃผ์ ๊ฒฐ๊ณผ๋ ๋ค์๊ณผ ๊ฐ๋ค.
Zn2+์ด์จ์ Fe2+์ด์จ์ ๋ํ ๋ถ๋ถ ์นํ์ ๋ฐ๋ผ ๋จ๊ฒจ์ง Fe2+์ด์จ์ ๊ณต๊ธฐ ์ค์์ ์ฝ๊ฒ Fe3+์ด์จ์ผ๋ก ์ฐํ๋์ด ์๋ถํด๋ฅผ ์ ๋ฐํ๊ธฐ ๋๋ฌธ์ Zn๊ฐ ๋ถ๋ถ์ ์ผ๋ก ์นํ๋ ํฅ์ฌํ๋ผ์ดํธ๋ฅผ ํฉ์ฑํ๊ธฐ ์ํด์๋ ์๋ก์ด ํฉ์ฑ ๋ฐฉ๋ฒ์ด ํ์ํ๋ค. ๋ฐ๋ผ์, Zn2+์ด์จ์ ๋ถ๋ถ ์นํ์ ์์์ 10-3โ10-2 atm์ ๋ฎ์ PO2์์ ์๊ฒฐ ๋ฐ ๋
ธ๋์ ํตํด ์นํ๋์ง ์์ ์คํธ๋ก ํฌ W-ํ์
ํฅ์ฌํ๋ผ์ดํธ (SrFe18O27SrW)์ ํฉ์ฑ์ ์๋ํ์๋ค. ๊ฒฐ๊ณผ์ ์ผ๋ก, ๋ค๊ฒฐ์ ์ SrW ๋จ์ผ์ ์ํธ์ 10-3 atm์ PO2 ๋ถ์๊ธฐ ์๋1300-1315โ์์ ์๊ฒฐ ํ ๋
ธ๋ํจ์ผ๋ก์จ ์ป์ ์ ์์๋ค. ๋ํ SrW ์์ 10-3์ PO2์์ 1245 ยฑ 5์ 1320 ยฑ 5โ ์ฌ์ด์ ์จ๋ ์์ญ์์, 10-2์ PO2์์ 1275 ยฑ 5์ 1380 ยฑ 5 โ ์ฌ์ด์ ์จ๋ ์์ญ์์ ์์ ํ ๊ฒ์ผ๋ก ๋ํ๋ฌ์ผ๋ฉฐ, ๊ฒฐ์ ๋ ์ ์์ ์จ๋ ์์ญ์ ํ ๋๋ก SrW์ ์ ์์ ๋๋ฅผ 10-3-0.21 atm์ PO2 ์์ญ์์ ๊ทธ๋ฆด ์ ์์๋ค.
SrW์ ๋จ์ผ์์ด 10-3atm์ PO2์์ ์๊ฒฐ ๋ฐ ๋
ธ๋์ ์ํด ์ป์ด์ง์ ๋ฐ๋ผ, Zn๊ฐ ์นํ๋ ์คํธ๋ก ํฌ W-ํ์
ํฅ์ฌํ๋ผ์ดํธ (SrZnxFe2-xFe16O27SrZnxFe2-xW, 0.5 โค x โค 2.0) ๋ค๊ฒฐ์ ์ํธ์ ๊ฐ์ ๋ฐฉ์์ผ๋ก ํฉ์ฑํ๊ณ ์ ํ๋ค. ๊ทธ ๊ฒฐ๊ณผ, x = 1.0๊น์ง SrZnxFe2-xW-ํ์
๊ณ ์ฉ์ฒด (0.0 โค x โค 1.0)๋ฅผ ์ป์ ์ ์์๊ณ , x โฅ 1.25์ ๊ฒฝ์ฐ SrZnFeFe16O27๊ณผ ZnFe2O4์ ๋ ์์ด ํผํฉ๋ ์ํธ์ด ์ป์ด์ก๋ค. ๋ํ 10-3atm์ PO2์์ SrZnxFe2-xW ์์ ์ ์์ ์์ญ์ x = 0.0, 0.5 ๋ฐ 1.0์ผ ๋ ๊ฐ๊ฐ 1245 ยฑ 5-1320 ยฑ 5 โ, 1210 ยฑ 5-1285 ยฑ 5 โ, ๋ฐ 1190 ยฑ 5-1255 ยฑ 5 โ,์ธ ๊ฒ์ผ๋ก ํ์ธ๋์๋ค. ์๊ธฐ์ ํน์ฑ ์ธก์ ๊ฒฐ๊ณผ, Fe2+์ด์จ ์๋ฆฌ์ ๋ํ Zn2+์ด์จ์ ์นํ์ด ์คํธ๋ก ํฌ W-ํ์
ํฅ์ฌํ๋ผ์ดํธ์ ํฌํ ์ํ ๊ฐ (Ms)์ ํฅ์์ ํจ๊ณผ์ ์ด๋ผ๋ ๊ฒ์ด ๋ฐํ์ก๋ค. x๊ฐ 1.0๊น์ง ์ฆ๊ฐํจ์ ๋ฐ๋ผ, Ms ๊ฐ์ด ์ฆ๊ฐํ์๊ณ , 1250โ์์ ์๊ฒฐ๋ x = 1.0์ ์ํธ์ผ๋ก๋ถํฐ ์ต๋87.7emu/g์ Ms ๊ฐ์ ์ป์ ์ ์์๋ค. ๋ํ, ์์ํ ์ฐ์ ๋ถ์๊ธฐ ์๋ 300โ์์ ์ค์ํ ์ํธ์ ์ฐ์ ์ด์ฒ๋ฆฌ๋ฅผ ํตํด ์๊ฒฐ ์จ๋๊ฐ ์ฆ๊ฐํจ์ ๋ฐ๋ผ ์ํธ์ ์ฐ์ ๋นํํ๋๋ก ์ด ์ฆ๊ฐํ๋ฉฐ Ms, ๋จ์ ์
๋ถํผ ๋ฐ ์ ๊ธฐ ์ ๋๋๊ฐ ์ฆ๊ฐํ๋ ๊ฒ์ผ๋ก ๋ํ๋ฌ๋ค.
๋ํ Zn๊ฐ ์นํ๋ ๋ฐ๋ฅจ Y-ํ์
ํฅ์ฌํ๋ผ์ดํธ (Ba2ZnxFe2-xFe12O22, Ba2ZnxFe2-xY, 0.5 โค x โค 2.0) ๋ํ 10-3atm์ PO2์์ ์๊ฒฐ ํ ๋
ธ๋์ ํตํด ํฉ์ฑ๋์๋ค. x๊ฐ 0.5, 1.0 ๋ฐ 1.5์ผ ๋ PO2 = 10-3 atm์์ ๊ณ ์จ ์๊ฒฐ ๋ฐ ๋
ธ๋์ ํตํด ์ฑ๊ณต์ ์ผ๋ก ๋จ์ผ์์ ์ป์ ์ ์์์ง๋ง, x = 2.0 ์ธ ๊ฒฝ์ฐ์๋ ๊ณต๊ธฐ ์ค์์์ ์๊ฒฐ์ ํตํด์๋ง ๊ทธ ๋จ์ผ์์ ์ป์ ์ ์์๋ค. Ms ๊ฐ์ x๊ฐ 0.5์์ 1.0์ผ๋ก ์ฆ๊ฐํจ์ ๋ฐ๋ผ ์ฆ๊ฐํ๋ค๊ฐ ์ดํ, x๊ฐ 2.0๊น์ง ์ฆ๊ฐํจ์ ๋ฐ๋ผ ๊ฐ์ํ์๋ค. ๊ฒฐ๊ณผ์ ์ผ๋ก, 10-3atm์ PO2 ๋ถ์๊ธฐ ์๋ 1300 โ์์ 2 ์๊ฐ ๋์ ์๊ฒฐ๋ x = 1.0์ ์ํธ์ผ๋ก๋ถํฐ 44.7 emu/g์ ๊ฐ์ฅ ๋์ Ms ๊ฐ์ ์ป์ ์ ์์๋ค.
SrZnxFe2-xW์ Ba2ZnxFe2-xY์ ๋ง์ดํฌ๋กํ ํก์ ํน์ฑ์ 0.5-18 GHz์ ์ฃผํ์ ๋ฒ์์์ ์ดํด๋ณด์๋ค. ์ด๋ฅผ ์ํด, ์ํญ์ ์์ง๋ฅผ ๋ชจ์ฒด๋ก ํ๊ณ , 30, 50, 70 ๋ฐ 90 vol%์ ๋ถํผ ๋ถ์จ์ ๊ฐ๋ SrZnxFe2-xW (x = 0.0, 0.5, 1.0 ๋ฐ 2.0) ๋ฐ Ba2ZnxFe2-xY (x = 0.5, 1.0, 1.5 ๋ฐ 2.0)๋ฅผ ์ถฉ์ง์ฌ๋ก ํ๋ ๋ณตํฉ์ฒด๋ฅผ ์ ์ํ์๋ค. ๊ฒฐ๊ณผ์ ์ผ๋ก, SrZnxFe2-xW (x = 0.0, 0.5 ๋ฐ 1.0) ๋ฐ Ba2ZnxFe2-xY (x = 0.5, 1.0 ๋ฐ 1.5)๋ก ๋ง๋ค์ด์ง ๋ณตํฉ ์ฒด๋ ์ธก์ ๋ ์ฃผํ์ ๋ฒ์์์ SrZn2W (x = 2.0) ๋ฐ Ba2Zn2Y (x = 2.0)๋ก ์ ์กฐ๋ ๋ณตํฉ์ฒด์ ๋นํด ํฐ ฮตr๊ฐ์ ๋ํ๋๋๋ฐ, ์ด๋ Fe2+์ด์จ๊ณผ Fe3+์ด์จ ๊ฐ์ ์ ์ ๋์ฝ์ ๋ฐ๋ฅธ ๋ถ๊ทน์ ์ฆ๊ฐ ๋๋ฌธ์ผ๋ก ๋ณด์ธ๋ค. SrZnxFe2-xW (x = 0.0, 0.5 ๋ฐ 1.0) ๋ฐ Ba2ZnxFe2-xY (x = 0.5, 1.0 ๋ฐ 1.5)๋ก ์ ์กฐ ๋ ๋ณตํฉ์ฒด์ ฮผr๊ฐ ๋ํ SrZn2W ๋ฐ Ba2Zn2FeY์ ๋ณตํฉ์ฒด๋ณด๋ค ๋ ์ปธ๋ค. ํฅ์๋ ฮผr ๋ฐ ฮตr๋๋ฌธ์, Zn๊ฐ ๋ถ๋ถ์ ์ผ๋ก ์นํ๋ W ๋ฐ Y-ํ์
ํฅ์ฌํ๋ผ์ดํธ๋ก ์ ์กฐ ๋ ๋ณตํฉ์ฒด๋ ์๋์ ์ผ๋ก ๋ฎ์ ํ๋ผ์ดํธ ๋ถํผ ๋ถ์จ ๋ฐ ๋๊ป๋ก๋ ํฅ์๋ ๋ง์ดํฌ๋กํ ํก์ ํน์ฑ์ ๋ํ๋๋ค. ๊ฒฐ๊ณผ์ ์ผ๋ก, Zn2+์ด์จ์ ๋ถ๋ถ ์นํ์ ๋ง์ดํฌ๋กํ ํก์ ํน์ฑ์ ํฅ์๊ณผ ๋ง์ดํฌ๋กํ ํก์์ฒด์ ์ค๋ ๋ฐ ๋๊ป์ ๊ฐ์์ ํจ๊ณผ์ ์ด๋ผ๋ ๊ฒ์ ์ ์ ์์๋ค.With the development of information and communication technology, the use of high-performance mobile phones, household appliances, and advanced electronic devices are increasing. However, along with the fact that the sizes of electronic devices become smaller and more complicated with increasing their working frequencies, the electromagnetic interference (EMI) becomes a serious problem as electromagnetic waves emitted by electronic devices may interfere the operation of adjacent electronic devices causing malfunction. Therefore, the industrial demand for electromagnetic shielding technique that shields the incident electromagnetic signals and protects the electronic devices is growing in order to cope with the EMI problem. Among the electromagnetic shielding technique, the electromagnetic wave absorbing technique that absorbs or attenuate the unwanted incident electromagnetic waves, particularly the microwaves having GHz frequencies has drawn the attention of many researchers.
As the microwave absorption properties of microwave absorber mainly depend on the relative complex permeability (ฮผr = ฮผสน โ jฮผสนสน) and permittivity (ฮตr = ฮตสน โ jฮตสนสน) of the absorbing materials, various dielectric and magnetic materials have been extensively studied for microwave absorber applications. Among the various microwave absorbing materials, ferromagnetic oxide materials of hexaferrites are one of the promising candidates for microwave absorber application as they exhibit suitable ฮผr and ฮตr values at the GHz frequency region and as well as excellent chemical stability and low production cost. Thus in this study, we tried to synthesize the W and Y-type hexaferrites having novel chemical compositions and investigate their microwave absorption properties for the first time. To this end, the partial substitution of Zn2+ for Fe2+ leaving Fe2+ ions behind was carried out for the W and Y-type hexaferrites by sintering in the low oxygen pressure (PO2). Moreover, their phase stability, magnetic properties and microwave absorption properties were investigated. The major results are as the followings.
Since the partial substitution of Zn2+ for Fe2+ leaves Fe2+ ions behind, and the Fe2+ ions are easily oxidized to Fe3+ inducing phase decomposition, a novel synthesis method is necessary for the synthesis of partially Zn-substituted hexaferrites. Therefore, the synthesis of non-substituted strontium W-type hexaferrite (SrFe18O27SrW) was attempted by sintering and subsequent furnace-cooling in the low PO2 of 10-3โ10-2 atm before the conduction of partial substitution of Zn2+. As a result, the single phase of SrW polycrystalline samples were obtainable by sintering at 1300โ1315หC and subsequent furnace-cooling to room temperature in the PO2 of 10-3 atm. In addition, the SrW phase was found to be stable at the temperature region between 1245 ยฑ 5 and 1320 ยฑ 5หC in the PO2 of 10-3, and between 1275 ยฑ 5 and 1380 ยฑ 5หC in the PO2 of 10-2 atm. With the determined phase stability regions, a stability phase diagram of SrW on the PO2 versus 10,000/T (K) plot in the PO2 region of 10-3โ0.21 atm was constructed.
As the SrW single phase was obtained by sintering and subsequent furnace-cooling in the PO2 of 10-3 atm, the Zn-substituted strontium W-type hexaferrite (SrZnxFe2-xFe16O27SrZnxFe2-xW, 0.5 โค x โค 2.0) polycrystalline samples were tried to be prepared in the same manner. As a result, SrZnxFe2-xW-type solid solutions (0.0 โค x โค 1.0) could be obtained up to x = 1.0, while two-phase mixture of SrZnFeFe16O27 and ZnFe2O4 was obtainable for x โฅ 1.25. And also, the phase stability regions of SrZnxFe2-xW phase in the PO2 of 10-3 atm was found to be 1245 ยฑ 5โ1320 ยฑ 5หC, 1210 ยฑ 5โ1285 ยฑ 5หC, and 1190 ยฑ 5โ1255 ยฑ 5หC, for x = 0.0, 0.5, and 1.0, respectively. The magnetic property measurement revealed that the Zn2+ substitution for the Fe2+ site was found to be effective for the improvement of the saturation magnetization (Ms) of strontium W-type hexaferrite (SrFe18O27). With increasing x up to 1.0, Ms values were monotonously increased and the highest Ms value of 87.7 emu/g was obtained from the sample of x = 1.0 sintered at 1250หC. In addition, post-annealing heat treatments of samples for oxygenation at 300หC in pure oxygen gas revealed that oxygen non-stoichiometry increased with increasing the sintering temperature, leading to the increase in Ms, unit cell volume, and electrical conductivity.
Furthermore, the Zn-substituted barium Y-type hexaferrites (Ba2ZnxFe2-xFe12O22Ba2ZnxFe2-xY, 0.5 โค x โค 2.0) were also prepared by sintering and subsequent furnace-cooling in the PO2 of 10-3 atm. After high-temperature sintering and subsequent furnace-cooling in the PO2 = 10โ3 atm, the single-phase samples of x = 0.5, 1.0, and 1.5 were successfully prepared while the single-phase sample with x = 2.0 was obtainable only by sintering in air. The Ms value was first increased with increasing x from 0.5 to 1.0 and then decreased with further increasing x up to x = 2.0. As a result, the highest Ms value of 44.7 emu/g was obtainable from the sample of x = 1.0 sintered at 1300ยฐC for 2 h in the PO2 of 10โ3 atm.
The microwave absorption properties of SrZnxFe2-xW and Ba2ZnxFe2-xY in the frequency range of 0.5โ18 GHz were investigated. For this, the composites having epoxy resin as a matrix, and SrZnxFe2-xW (x = 0.0, 0.5, 1.0, and 2.0) and Ba2ZnxFe2-xY (x = 0.5, 1.0, 1.5, and 2.0) as magnetic fillers were fabricated with the ferrite volume fractions of 30, 50, 70, and 90 vol%. As a result, the composites made of SrZnxFe2-xW (x = 0.0, 0.5, and 1.0), and Ba2ZnxFe2-xY (x = 0.5, 1.0, and 1.5) exhibited larger ฮตr values in the measured frequency range than the composite made of SrZn2W (x = 2.0) and Ba2Zn2Y (x = 2.0) that is attributable to the enhanced polarization due to the electron hopping between Fe2+ and Fe3+ ions. The ฮผr values of the composites made of SrZnxFe2-xW (x = 0.0, 0.5, and 1.0), and Ba2ZnxFe2-xY (x = 0.5, 1.0, and 1.5) were also larger than the composites of SrZn2W and Ba2Zn2FeY. Owing to the increased ฮผr and ฮตr, the composites made of the partially Zn-substituted W and Y-type hexaferrites exhibited enhanced microwave absorption properties even with a lower ferrite volume fraction and absorber thickness. Consequently, the partial substitution of Zn2+ was found to be effective in the reduction of microwave absorber weight and absorber thickness with enhanced microwave absorption properties.Chapter 1. Introduction 1
Chapter 2. General background 11
2.1 Hexaferrites 11
2.2 Theory of microwave absorption 14
2.3 Microwave absorbing materials 18
Chapter 3. Synthesis of strontium W-type hexaferrites in low oxygen pressure and their phase stability 29
3.1 Introduction 29
3.2 Experimental 30
3.3 Results and discussion 32
3.3.1 Preparation of SrW in air 32
3.3.2 Preparation of SrW in PO2 = 10-3 atm 32
3.3.3 Determination of the lower phase boundary of SrW in PO2 = 10-3 atm 35
3.3.4 Determination of the upper phase boundary of SrW in PO2 = 10-3 atm 37
3.3.5 Phase stability of SrW in PO2 = 10-2 atm 38
3.3.6 Stability phase diagram of SrW in PO2 = 10-30.21 atm 40
3.4 Summary 42
Chapter 4. Synthesis of Zn-substituted W-type hexaferrites in the PO2 of 10-3 atm and their magnetic properties 59
4.1 Introduction 59
4.2 Experimental 60
4.3 Results and discussion 61
4.3.1 Synthesis of SrZnxFe2-xW (x = 0.0, 0.5, 1.0, 1.25, 1.5, and 2.0) in PO2 = 10-3 atm 61
4.3.2 Phase stability of SrZnxFe2-xW (x = 0.0, 0.5, and 1.0) in PO2 = 10-3 atm 63
4.3.3 Structural and magnetic properties of SrZnxFe2-xW (x = 0.0, 0.5, and 1.0) in PO2 = 10-3 atm 67
4.4 Summary 75
Chapter 5. Synthesis of Zn-substituted Y-type hexaferrites in the PO2 of 10-3 atm and their magnetic properties 93
5.1 Introduction 93
5.2 Experimental 95
5.3 Results and discussion 96
5.4 Summary 104
Chapter 6. Microwave absorption properties of Zn-substituted W and Y-type hexaferrites 121
6.1 Introduction 121
6.2 Experimental 122
6.3 Results and discussion 123
6.3.1 Complex permittivity and permeability spectra 123
6.3.2 Microwave absorption properties 128
6.4 Summary 135
Chapter 7. Conclusion 169
Appendices 173
A. Measurement of complex permittivity and permeability 173
B. Impedance matching solution map 181
Abstract in Korean 191
Achievement 195Docto
Imperforate Cloacal Membrane(Two Autopsy cases report)
Congenital malformations of ano-recturn are relatively
common and have many variation in the level
of obstruction and presence or type of fistula. Ladd
and Gross (1934), Wilkinson (1972) classified these
anomalies and their classifications are widely used
clinically and pathologically.
Cheng et al. (1974) reported 5 cases of persistent
cloaca with review of 50 cases reported previously.
All of these cases have single perineal opening and the
rectums are connected either to bladder or to vagina.
Because of the fact that 362 out of 507 cases with
imperforate anus have rectovaginal, rectovesical or
rectourethral fistula (Gross, 1934), it is often difficult
to distinguish the persistent cloaca from imperforate
anus with fistula formation. And most of the fistula
found in patients with imperforate anus are likely
to be the unobliterated cloacal canal.
We report two cases of imperforate anus of another
variety that could best be understood along with
imperforate cloacal membrane. These patients were deficient of both anus and urethral opening, and the
bladder and rectum had free communication.
Case 1 was a full-term male infant who died soon
after birth. He had rudimentary phallus without
opening. Midline fold of buttock was absent. No
perineal opening was found. Both feet had four digits
each. Abdominal cavity contained two cystic masses
and two kidneys. Two ureters of the kidneys drained
into one of the cysts, and the other cyst was connected
to the rectum. Between these two cysts there
was free communication with a large opening. Neither
urethral opening nor anal opening were found in
and outside the cysts.
Case 2 was a baby who was delivered by Cvsection
at 6 months of gestational age. External genitalia
and anal canal could not be seen externally. The
abdomen was markedly distended and was near-totally
replaced by huge cyst containing yellowish fluid. Both
ureters and rectum were connected to this huge
abdominal cyst
Incidence of so-called in situ Neuroblastoma in the Fetal Adrenals
Neuroblastic cell nests seen in infant adrenal gland
are often called in situ neuroblastoma. The significance
of these neuroblastic cell nests in adrenals of
neonates is still in debate.
It has been the mainpoint of discussion whether
these neuroblastic cell nests could develop into clinical
neuroblastoma, and if so, what would be chance? It
was our purpose to examine the fetal adrenal glands
to determine the incidence of neuroblastic cell nests
in varying gestational periods. A total 113 pairs of adrenal from fetuses ranging from 10 to 42 weeks
and 13 neonates within one week of age were
removed at autopsy and serially sectioned.
The following results were obtained:
l. Neuroblastic cell nests were fairly commonly
seen in fetal adrenal glands, being 37. 2% in overall
incidence.
2. The incidence of neuroblastic cell nests in fetal
adrenals was remarkably different by different gestational
periods. In general the earlier the gestational
age, more often these cell nests were observed. Full
term fetuses and neonates were almost completely
devoid of neuroblastic cell nests in adrenal glands.
3. Although cytologically neuroblastic cell nests
seen in this study are indistinguishable from clinical
neuroblastoma, these cell nests showed a tendency
of regression in terms of frequency of finding
neuroblastic cell nests as fetal age advances.
4. Neuroblastic cell nests seen in fetal adrenal do
not appear to be normal embryological phenomenon
of adrenal medullary maturation
Proactive Virtual Network Function Live Migration using Machine Learning
VM (Virtual Machine) live migration์ VM์์ ๋์ํ๋ ์๋น์ค์ downtime์ ์ต์ํํ๋ฉด์ ํด๋น VM์ ๋ค๋ฅธ ์๋ฒ ๋
ธ๋๋ก ์ด์ ์ํค๋ ์๋ฒ ๊ฐ์ํ ๊ธฐ์ ์ด๋ค. ํด๋ผ์ฐ๋ ๋ฐ์ดํฐ์ผํฐ์์๋ ๋ก๋๋ฐธ๋ฐ์ฑ, ํน์ ์์น ์๋ฒ๋ก์ consolidation ํตํ ์ ๋ ฅ ์๋น ๊ฐ์, ์๋ฒ ์ ์ง๋ณด์(maintenance) ์์
์ค์๋ ์ฌ์ฉ์์๊ฒ ๋ฌด์ค๋จ ์๋น์ค๋ฅผ ์ ๊ณตํ๊ธฐ ์ํ ๋ชฉ์ ๋ฑ์ผ๋ก VM live migration ๊ธฐ์ ์ด ํ๋ฐํ ์ฌ์ฉ๋๊ณ ์๋ค. ๋ํ ๊ณ ์ฅ ๋ฐ ์ฅ์ ์ํฉ์ด ์์ธก๋๊ฑฐ๋ ๊ทธ ์งํ๊ฐ ํ์ง๋๋ ๊ฒฝ์ฐ, ์๋ฐฉ ๋ฐ ์ํ ์๋จ์ผ๋ก ํ์ฉ๋ ์ ์๋ค. ๋ณธ ๋
ผ๋ฌธ์์ ์ฐ๋ฆฌ๋ ๋ ๊ฐ์ง ์ ์ ์ (proactive) VNF live migration ๋ฐฉ๋ฒ์ ์ ์ํ๋ฉฐ, ์ฒซ ๋ฒ์งธ ๋ฐฉ๋ฒ์ ์๋ฒ ๋ก๋๋ฐธ๋ฐ์ฑ์ VNF live migration ๊ธฐ๋ฒ์ ์ฌ์ฉํ๋ฉฐ ๋ ๋ฒ์งธ ๋ฐฉ๋ฒ์ ๊ณ ์ฅ ์์ธก์ ๊ธฐ๋ฐํ์ฌ ๊ณ ์ฅ ํํผ ๋ชฉ์ ์ผ๋ก VNF live migration์ ์ฌ์ฉํ๋ค. ์ ์ ์ migration์ ์ํ ์์ธก์ ๋จธ์ ๋ฌ๋(๊ธฐ๊ณํ์ต)์ ํ์ฉํ๋ฉฐ ์คํ์ ํตํด ๊ทธ ์คํจ์ฑ์ ๊ฒ์ฆํ๋ค. ํนํ ๋ ๋ฒ์งธ ๋ฐฉ๋ฒ์ ๋ํด vEPC (Virtual Evolved Packet Core)์ ๊ณ ์ฅ ์ํฉ์ case studyํ ๊ฒฐ๊ณผ๋ฅผ ์ ์ํ๋ค.22Nkc