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Kaolin 懸濁液에 있어서 K-Alum의 凝集에 pH가 미치는 影響
金昺圭,鄭雲璇 成均館大學校 科學技術硏究所 1984 論文集 Vol.35 No.1
Investigation was carried out to find the effect of pH on flocculation of kaolin suspended in water using K-Alum. The particle size was about 0.57 micron and the volume concentration of kaolin suspended was about 0.0008(ø_k). The relative turbidity was calculated as the ratio of absorbance at 20℃ by spectrophotometer. The results are as follows; 1. Irrespective of pH, 1) With increasing flocculant dosage, the settling time of perfect flocculation decreased gradually and the settling velocity increased slightly. 2) Logarithmic relationship between the initial settling velocity in terms of (-dt/dA)_t→0 and thee critical flocculated concentration of K-Alum is as follow, log(-dt/dA)_t→0 = -mlog C_c.f.c + b 3) Because of cationic antagonism between potassium ion and aluminium ion in kaolin suspension, the flocculating power of aluminium ion decreased slightly. 2. With increasing pH in kaolin suspension, the flocculating power of K-Alum was weakened and constants, m, b increased gradually.
토사터널의 쉴드 TBM 데이터 시계열 분석을 통한 막장 전방 예측 연구
정지희,김병규,정희영,김해만,이인모 사단법인 한국터널지하공간학회 2019 한국터널지하공간학회논문집 Vol.21 No.2
This paper presents a method to predict ground types ahead of a tunnel face utilizing operational data of the earth pressure-balanced (EPB) shield tunnel boring machine (TBM) when running through soil ground. The time series analysis model which was applicable to predict the mixed ground composed of soils and rocks was modified to be applicable to soil tunnels. Using the modified model, the feasibility on the choice of the soil conditioning materials dependent upon soil types was studied. To do this, a self-organizing map (SOM) clustering was performed. Firstly, it was confirmed that the ground types should be classified based on the percentage of 35% passing through the #200 sieve. Then, the possibility of predicting the ground types by employing the modified model, in which the TBM operational data were analyzed, was studied. The efficacy of the modified model is demonstrated by its 98% accuracy in predicting ground types ten rings ahead of the tunnel face. Especially, the average prediction accuracy was approximately 93% in areas where ground type variations occur. 토압식(Earth Pressure-Balanced, EPB) 쉴드 TBM 기계데이터 분석을 통해 토사터널의 특징이 반영된 막장 전방 예측방법을 제안하였다. 기존에 암반과 토사가 혼합된 복합 지반의 예측에 적용하였던 시계열 분석 모델을 토사터널에 적용가능하도록 수정하였다. 또한 수정된 모델을 사용하여, 토사 종류에 따라 쏘일 컨디셔닝 재료를 선택하는 것이 타당한지연구하였다. 이를 위해 Self-Organizing Map (SOM) 군집화(clustering) 분석을 수행하였다. 그 결과 무엇보다도 지반타입이 #200체 통과량 35% 기준으로 분류되어야 한다는 것을 확인하였다. 또한 TBM 기계데이터 분석을 통해 수정된모델이 지반 타입을 예측하는데 사용될 수 있음을 확인하였다. 수정된 기준에 따라 지반 타입을 분류하고 시계열 분석을수행하면, 10막장 전방 지반에 대해서 98%의 높은 예측 정확도를 보였으며, 이를 통해 수정된 방법의 우수성이 입증되었다. 특히 지반 타입 변화 구간에 대한 예측 정확도도 약 93%로, 10막장 전방에서 지반 타입 변화 여부를 미리 확인할수 있게 되었다
박영빈,김병규,임재영,남기웅,김소아람,이상헌,정재학 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.3
ZnO films were deposited on Si (100) substrates by using a two-step growth process. In the firststep, ZnO nanorods were grown by using the hydrothermal method at 140 C for 5 min. In thesecond step, a ZnO amorphous layer was deposited on the ZnO nanorods by spin-coating. Aftercompletion of the growth process, the films were annealed at 800 C for 10 min, and a ZnO activelayer was deposited on top of the amorphous layer by using plasma-assisted molecular beam epitaxy. Further, temperature-dependent photoluminescence (PL) measurement were conducted to study theoptical properties of the prepared films. In the low-temperature PL spectra, emission peaks in thenear-band-edge region were observed at 3.370, 3.362, 3.347, 3.329, 3.317, 3.288, 3.263, 3.219, 3.191,and 3.116 eV; these peaks were attributed to free excitons, neutral donor bound excitons, neutralacceptor donor excitons, two electron satellites, and donor acceptor pairs, respectively. Thesepeaks were red-shifted, and their intensity decreased with increasing temperature. The bindingenergy of the donor was calculated as 43.1 meV by using the Haynes rule. Further, the valueand , factors in the equation for the energy of localized excitons of donors and acceptors wereobtained as 0.73 meV and 750 K, respectively, by fitting the free exciton (FX) peak according toVarshni’s equation. The full width at half-maximum of PL for the films was about 95.1 meV atroom temperature; moreover, the following values were obtained for the films by using theoreticalequations: the background impurity broadening, I0 = 62 meV, the parameter describing exciton-LO phonon interaction, ΙLO = 80 meV, LO phonon energy, ~!LO = 72 meV, and, the couplingstrength of an exciton-acoustic phonon interaction,ph = 0.087 meV/K Furthermore, the activationenergy was about 60.1 meV. ZnO films were deposited on Si (100) substrates by using a two-step growth process. In the firststep, ZnO nanorods were grown by using the hydrothermal method at 140 C for 5 min. In thesecond step, a ZnO amorphous layer was deposited on the ZnO nanorods by spin-coating. Aftercompletion of the growth process, the films were annealed at 800 C for 10 min, and a ZnO activelayer was deposited on top of the amorphous layer by using plasma-assisted molecular beam epitaxy. Further, temperature-dependent photoluminescence (PL) measurement were conducted to study theoptical properties of the prepared films. In the low-temperature PL spectra, emission peaks in thenear-band-edge region were observed at 3.370, 3.362, 3.347, 3.329, 3.317, 3.288, 3.263, 3.219, 3.191,and 3.116 eV; these peaks were attributed to free excitons, neutral donor bound excitons, neutralacceptor donor excitons, two electron satellites, and donor acceptor pairs, respectively. Thesepeaks were red-shifted, and their intensity decreased with increasing temperature. The bindingenergy of the donor was calculated as 43.1 meV by using the Haynes rule. Further, the valueand , factors in the equation for the energy of localized excitons of donors and acceptors wereobtained as 0.73 meV and 750 K, respectively, by fitting the free exciton (FX) peak according toVarshni’s equation. The full width at half-maximum of PL for the films was about 95.1 meV atroom temperature; moreover, the following values were obtained for the films by using theoreticalequations: the background impurity broadening, I0 = 62 meV, the parameter describing exciton-LO phonon interaction, ILO = 80 meV, LO phonon energy, ~!LO = 72 meV, and, the couplingstrength of an exciton-acoustic phonon interaction,ph = 0.087 meV/K Furthermore, the activationenergy was about 60.1 meV.
Early Coding Unit–Splitting Termination Algorithm for High Efficiency Video Coding (HEVC)
Kalyan Goswami,김병규,전동산,정순흥,최진수 한국전자통신연구원 2014 ETRI Journal Vol.36 No.3
A new-generation video coding standard, named HighEfficiency Video Coding (HEVC), has recently beendeveloped by JCT-VC. This new standard provides asignificant improvement in picture quality, especially forhigh-resolution videos. However, one the most importantchallenges in HEVC is time complexity. A quadtree-basedstructure is created for the encoding and decodingprocesses and the rate-distortion (RD) cost is calculatedfor all possible dimensions of coding units in the quadtree. This provides a high encoding quality, but also causescomputational complexity. We focus on a reductionscheme of the computational complexity and propose anew approach that can terminate the quadtree-basedstructure early, based on the RD costs of the parent andcurrent levels. Our proposed algorithm is compared withHEVC Test Model version 10.0 software and a previouslyproposed algorithm. Experimental results show that ouralgorithm provides a significant time reduction forencoding, with only a small loss in video quality.