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      • Residual Multi-dilated convolution U-Net을 이용한 다중 심장 영역 분할 알고리즘 연구

        임상헌 ( Sang-heon Lim ),최한승 ( H. S. Choi ),배희진 ( S. K. Jung ),정서경 ( J. K. Jung ),정진교 ( Myung-suk Lee ),이명숙 한국정보처리학회 2019 한국정보처리학회 학술대회논문집 Vol.26 No.1

        본 연구에서는 딥 러닝을 이용하여 완전 자동화된 다중 클래스 전체 심장 분할 알고리즘을 제안하였다. 제안된 방법은 recurrent convolutional block과 residual multi-dilated block을 삽입하여 기존 U-Net을 개선한 인공신경망 모델을 사용하였다. 평가는 자동화 분석 결과와 수동 평가를 비교하였다. 그 결과 96.88%의 평균 DSC, 95.60%의 정확도, 97.00%의 recall을 얻었다. 이 실험 결과는 제안된 방법이 다양한 심장 구조에서 효과적으로 구분되어 수행되었음을 알 수 있다. 본 연구에서 제안된 알고리즘이 의사와 방사선 의사가 영상을 판독하거나 임상 결정을 내리는데 보조적 역할을 할 것을 기대한다.

      • KCI등재후보

        Control of Thermoelectric Properties through the addition of Ag in the Bi0.5 Sb1.5 Te3Alloy

        ( J. K. Lee ),( S. D. Kim ),( M. W. Oh ),( S. H. Cho ),( B. K. Min ),( H. W. Lee ),( M. H. Kim ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 ELECTRONIC MATERIALS LETTERS Vol.6 No.4

        In this study, the thermoelectric properties of the Ag-doped Bi0.5Sb1.5Te3 compounds were investigated in the temperature range from 323 K to 573 K. Ingots were fabricated by a conventional melting process and the powder crushed from ingots was then sintered using a hot-pressing method. The temperature dependence of the Seebeck coefficient and the electrical conductivity of the Ag-doped Bi0.5Sb1.5Te3compound are characteristic of degenerate semiconductors, which is fairly different from the conventional Bi0.5Sb1.5Te3 compound. The power factor (α 2 σ) of the quaternary compound was larger than that of the ternary, which is mainly due to the increase in the electrical conductivity with doping content of Ag. The thermal conductivity was greater than that of the Ag-freeBi0.5Sb1.5Te3compound in the temperature range from 323 K to 523 K. The lattice thermal conductivity showed low values throughout the temperature range. The maximum value of the dimensionless figure of merit (ZT) of the 0.05 wt. % Ag-doped compound and the ternary alloy were 1.2 at 373 K and 0.88 at 323 K, respectively. Each of the maximum peak ZT shifts to a higher temperature region with increases in the doping content of Ag. This is likely due to the control of the lattice thermal conductivity by the twin structure, which had a nano-ordered layer.

      • Solubility of oxcarbazepine in eight solvents within the temperature range T=(288.15-308.15)K

        Nam, K.,Ha, E.S.,Kim, J.S.,Kuk, D.H.,Ha, D.H.,Kim, M.S.,Cho, C.W.,Hwang, S.J. Academic Press 2017 The Journal of chemical thermodynamics Vol.104 No.-

        In this study, the solubility of oxcarbazepine in pure methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, acetonitrile, and tetrahydrofuran was analysed across the temperature range of 288.15-308.15K under atmospheric pressure by using a solid-liquid equilibrium method. The experimental values obtained data were correlated using the modified Apelblat model at each temperature. The mole fraction solubility of oxcarbazepine in all eight pure solvents increased gradually in a temperature-dependent manner. The highest mole fraction solubility of 3.08x10<SUP>-3</SUP> at 308.15K was observed for tetrahydrofuran, followed by acetone (1.82x10<SUP>-3</SUP> at 308.15K), acetonitrile (1.22x10<SUP>-3</SUP> at 308.15K), methanol (1.11x10<SUP>-3</SUP> at 308.15K), ethanol (6.17x10<SUP>-4</SUP> at 308.15K), 1-butanol (6.17x10<SUP>-4</SUP> at 308.15K), 1-propanol (6.16x10<SUP>-4</SUP> at 308.15K), and 2-propanol (4.13x10<SUP>-4</SUP> at 308.15K). The experimental solubility in all solvents correlated well with that calculated using the modified Apelblat equation across the temperature range of (288.15-308.15)K. Therefore, the experimental solubility and correlation equations established in this study could be useful during the crystallization/purification, pre-formulation, and formulation stages of oxcarbazepine production in laboratories and related industries.

      • Control of phonon transport by the formation of the Al2O3 interlayer in Al2O3-ZnO superlattice thin films and their in-plane thermoelectric energy generator performance

        Park, N. W.,Ahn, J. Y.,Park, T. H.,Lee, J. H.,Lee, W. Y.,Cho, K.,Yoon, Y. G.,Choi, C. J.,Park, J. S.,Lee, S. K. Royal Society of Chemistry 2017 Nanoscale Vol.9 No.21

        <P>Recently, significant progress has been made in increasing the figure-of-merit (ZT) of various nanostructured materials, including thin-film and quantum dot superlattice structures. Studies have focused on the size reduction and control of the surface or interface of nanostructured materials since these approaches enhance the thermopower and phonon scattering in quantum and superlattice structures. Currently, bismuth-tellurium-based semiconductor materials are widely employed for thermoelectric (TE) devices such as TE energy generators and coolers, in addition to other sensors, for use at temperatures under 400 K. However, new and promising TE materials with enhanced TE performance, including doped zinc oxide (ZnO) multilayer or superlattice thin films, are also required for designing solid-state TE power generating devices with the maximum output power density and for investigating the physics of in-plane TE generators. Herein, we report the growth of Al2O3/ZnO (AO/ZnO) superlattice thin films, which were prepared by atomic layer deposition (ALD), and the evaluation of their electrical and TE properties. All the in-plane TE properties, including the Seebeck coefficient (S), electrical conductivity (sigma), and thermal conductivity (kappa), of the AO/ZnO superlattice (with a 0.82 nm-thick AO layer) and AO/ZnO films (with a 0.13 nm-thick AO layer) were evaluated in the temperature range 40-300 K, and the measured S, s, and. were -62.4 and -17.5 mu V K-1, 113 and 847 (Omega cm)(-1), and 0.96 and 1.04 W m(-1) K-1, respectively, at 300 K. Consequently, the in-plane TE ZT factor of AO/ZnO superlattice films was found to be similar to 0.014, which is approximately two times more than that of AO/ZnO films (ZT of similar to 0.007) at 300 K. Furthermore, the electrical power generation efficiency of the TE energy generator consisting of four couples of n-AO/ZnO superlattice films and p-Bi0.5Sb1.5Te3 (p-BST) thin-film legs on the substrate was demonstrated. Surprisingly, the output power of the 100 nm-thick n-AO/ZnO superlattice film/p-BST TE energy generator was determined to be similar to 1.0 nW at a temperature difference of 80 K, corresponding to a significant improvement of similar to 130% and similar to 220% compared to the 100 nm-thick AO/ZnO film/p-BST and n-BT/p-BST film generators, respectively, owing to the enhancement of the TE properties, including the power factor of the superlattice film.</P>

      • Cooperative Activation of PI3K by Ras and Rho Family Small GTPases

        Yang, H.,Shin, M.G.,Lee, S.,Kim, J.R.,Park, W.,Cho, K.H.,Meyer, T.,Do Heo, W. Cell Press 2012 Molecular cell Vol.47 No.2

        Phosphoinositide 3-kinases (PI3Ks) and Ras and Rho family small GTPases are key regulators of cell polarization, motility, and chemotaxis. They influence each other's activities by direct and indirect feedback processes that are only partially understood. Here, we show that 21 small GTPase homologs activate PI3K. Using a microscopy-based binding assay, we show that K-Ras, H-Ras, and five homologous Ras family small GTPases function upstream of PI3K by directly binding the PI3K catalytic subunit, p110. In contrast, several Rho family small GTPases activated PI3K by an indirect cooperative positive feedback that required a combination of Rac, CDC42, and RhoG small GTPase activities. Thus, a distributed network of Ras and Rho family small GTPases induces and reinforces PI3K activity, explaining past challenges to elucidate the specific relevance of different small GTPases in regulating PI3K and controlling cell polarization and chemotaxis.

      • KCI우수등재

        확산펌프 기반의 BCl<SUB>3</SUB> 축전결합 플라즈마를 이용한 GaAs와 AlGaAs의 건식 식각

        이성현,박주홍,노호섭,최경훈,송한정,조관식,이제원,Lee, S.H.,Park, J.H.,Noh, H.S.,Choi, K.H.,Song, H.J.,Cho, G.S.,Lee, J.W. 한국진공학회 2009 Applied Science and Convergence Technology Vol.18 No.4

        본 논문은 확산펌프 기반의 축전 결합형 $BCl_3$ 플라즈마를 사용하여 GaAs와 AlGaAs를 건식 식각한 연구에 관한 것이다. 실험에서 사용한 압력 범위는 $50{\sim}180$ mTorr, CCP 파워는 $50{\sim}200\;W$, $BCl_3$ 가스 유량은 $2.5{\sim}10$ sccm 이었다. 식각 후에 GaAs와 AlGaAs의 식각 속도와 표면 거칠기분석은 표면 단차 측정기를 이용하여 하였다. GaAs의 식각 벽면과 표면 상태는 전자현미경으로 분석하였다. 식각 중 플라즈마의 광 특성 분석은 광학 발광 분석기를 이용하였다. 본 실험을 통하여 5 sccm의 소량의 $BCl_3$ 가스 유량으로 공정 압력이 130 mTorr이내인 경우에는, 100 W CCP 파워의 조건에서 GaAs는 약 $0.25{\mu}m$/min 이상의 우수한 식각 속도를 얻을 수 있었다. AlGaAs의 경우는 GaAs의 식각 속도보다 조금 낮았다. 그러나 같은 유량에서 공정압력이 180 mTorr로 높아지면 GaAs와 AlGaAs의 식각 속도가 급격히 감소하여 거의 식각되지 않는 것을 알 수 있었다. 또한 CCP 파워의 경우에는 50 W의 파워에서는 GaAs와 AlGaAs 모두 거의 식각되지 않았다. 그러나 $100{\sim}200\;W$의 조건에서는 $0.3{\mu}m$/min 이상의 높은 식각 속도를 주었다. 두 결과를 보았을 때 축전결합형 $BCl_3$ 플라즈마 식각에서 GaAs와 AlGaAs의 식각 속도는 CCP 파워가 $100{\sim}200\;W$ 범위에 있으면 그 값에 비례하지 않고 거의 일정한 값이 된다는 사실을 알았다. 75mTorr, 100 W의 CCP 파워 조건에서 $BCl_3$의 유량 변화에 따른 GaAs와 AlGaAs의 식각 속도의 경우, $BCl_3$의 유량이 2.5 sccm의 소량일 때는 GaAs는 식각 속도가 높았지만 AlGaAs는 거의 식각되지 않는 흥미로운 결과를 얻었다. 플라즈마 발광 특성을 보면 $BCl_3$ 축전 결합 플라즈마는 주로 $500{\sim}700\;mm$ 범위를 가지는 넓은 분자 피크만 만든다는 것을 알 수 있었다. 전자 현미경 사진 결과에서는 5 sccm과 10 sccm의 $BCl_3$ 플라즈마 모두 식각 중에 GaAs의 벽면을 언더컷팅 하였으며, 10 sccm의 $BCl_3$유량을 사용하였을 때 언더컷팅이 더 심했다. We report the etch characteristics of GaAs and AlGaAs in the diffusion pump-based capacitively coupled $BCl_3$ plasma. Process variables were chamber pressure ($50{\sim}180$ mTorr), CCP power ($50{\sim}200\;W$) and $BCl_3$ gas flow rate ($2.5{\sim}10$ sccm). Surface profilometry was used for etch rate and surface roughness measurement after etching. Scanning electron microscopy was used to analyze the etched sidewall and surface morphology. Optical emission spectroscopy was used in order to characterize the emission peaks of the $BCl_3$ plasma during etching. We have achieved $0.25{\mu}m$/min of GaAs etch rate with only 5 sccm $BCl_3$ flow rate when the chamber pressure was in the range of 50{\sim}130 mTorr. The etch rates of AlGaAs were a little lower than those of GaAs at the conditions. However, the etch rates of GaAs and AlGaAs decreased significantly when the chamber pressure increased to 180 mTorr. GaAs and AlGaAs were not etched with 50 W CCP power. With $100{\sim}200\;W$ CCP power, etch rates of the materials increased over $0.3{\mu}m$/min. It was found that the etch rates of GaAs and AlGaAs were not always proportional to the increase of CCP power. We also found the interesting result that AlGaAs did not etched at 2.5 sccm $BCl_3$ flow rate at 75 mTorr and 100 W CCP power even though it was etched fast like GaAs with more $BCl_3$ gas flow rates. By contrast, GaAs was etched at ${{\sim}}0.3{\mu}m$/min at the 2.5 sccm $BCl_3$ flow rate condition. A broad molecular peak was noticed in the range of $500{\sim}700\;mm$ wavelength during the $BCl_3$ plasma etching. SEM photos showed that 10 sccm $BCl_3$ plama produced more undercutting on GaAs sidewall than 5 sccm $BCl_3$ plasma.

      • KCI등재

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