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인공신경망에 의한 스터럽 없는 FRP 콘크리트 보의 전단강도 예측
이송희,이차돈 한국구조물진단유지관리학회 2011 한국구조물진단학회 학술발표회논문집 Vol.2011 No.9
Non-corrosive fiber reinforced plastics (FRPs) have been widely replacing steel bars or tendons used in concrete structures as flexural reinforcements. There are noticeable differences among the existing formulas in calculating the contributions of concrete to shear resistance of FRP beams. In this paper, the artificial neural network (ANN) technique is employed as an analytical alternative to existing methods for predicting shear capacity of FRP concrete beams. It was found that the developed ANN was able to predict more closely the shear strength of FRP beams.
Molecular Dynamics Simulation Study of the Ionic Mobility of OH<sup>-</sup> Using the OSS2 Model
이송희,Lee, Song-Hi Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.8
Anomalously high ionic mobilities of H+ and $OH^-$ are owing to the transfer of $H^+$ by the Grotthus chain mechanism. Molecular dynamics simulations for the system of 215 water including $OH^-$ ion at 298.15 K using the OSS2 model [J. Chem. Phys. 109, 5547 (1998)] as a dissociable water model with the use of Ewald summation were carried out in order to study the dynamics of $OH^-$ in water. The calculated ionic mobility of $OH^-$ is in good agreement with the experimental result and the Grotthus chain mechanism is fully understood.
단결정 실리콘에서 산소농도에 따른 산소석출결함 변화와 태양전지 효율에 미치는 영향
이송희,김성태,오병진,조용래,백성선,육영진,Lee, Song Hee,Kim, Sungtae,Oh, Byoung Jin,Cho, Yongrae,Baek, Sungsun,Yook, Youngjin 한국결정성장학회 2014 한국결정성장학회지 Vol.24 No.6
최근 태양전지의 효율을 증가시키기 위한 연구가 많이 이루어지고 있으며, 특히 단결정 실리콘 웨이퍼의 경우 높은 효율을 낼 수 있는 소재로써 고효율 태양전지연구에 많이 이용되고 있다. 본 연구에서는 단결정으로 Czochralski(Cz)-Si 성장 시 산소농도를 다르게 하여 산소석출결함의 변화와 그에 따른 셀효율과의 관계를 비교하였다. 산소불순물은 Cz법으로 성장시킨 실리콘의 주된 불순물이다. 산소불순물 존재 시 태양전지 공정에서 산소석출결함이 생성되며 발생된 산소석출결함은 셀효율에 악영향을 미치게 된다. 그러므로 고효율 태양전지를 위한 웨이퍼를 생산하기 위한 산소석출결함 밀도와 셀효율의 상관성을 연구하였다. 또한 산소농도에 따른 산소석출결함을 분석하여 산소석출결함이 발생되지 않는 잉곳 내 산소농도 범위를 연구하여 14.5 ppma 이하에서 Bulk Micro Defect(BMD)가 발생하지 않음을 확인하였다. Recent studies have shown methods of improving solar cell efficiency. Especially on single crystalline silicon wafer which is high-efficiency solar cell material that has been widely studied. Interstitial oxygen (Oi) is the main impurity in the Czochralski (Cz) growing method, and excess of this can form precipitates during cell fabrication. We have demonstrated the effect of Oi impurity and oxygen precipitation concentration of the wafer on Cz-silicon solar cell efficiency. The result showed a decrease in cell efficiency as Oi and oxygen precipitation increase. Moreover, we have found that the critical point of [Oi] to bring higher cell efficiency is at 14.5 ppma in non-existent Bulk Micro Defect (BMD).
Preliminary Molecular Dynamics Simulations of the OSS2 Model for the Solvated Proton in Water
이송희,Lee, Song Hui Korean Chemical Society 2001 Bulletin of the Korean Chemical Society Vol.22 No.8
The OSS2(Ojame-Shavitt-Singer 2)[L. Ojame et al., J. Chem. Phys. 109, 5547 (1998)] model as a dissociable water model is examined in order to study the dynamics of H+ in water. MD simulations for 216 water system, 215 water + H+ ion system, and 215 water + OH- ion system using the OSS2 model at 298.15 K with the use of Ewald summation are carried out. The calculated O-H radial distribution functions for these systems are essentially the same and are in very good agreement with that obtained by Ojame.
이송희,이무성,Lee, Song Hee,Lee, Moo Sung 한국산학기술학회 2017 한국산학기술학회논문지 Vol.18 No.4
본 연구는 유자의 과즙을 $50^{\circ}C$ 의 열수 추출물과 70%에탄올 추출물을 이용하여 항산화 효능과 항균효과를 2016년 11월부터 2017년 3월까지 실험하여 분석하였다. 실험결과는 모두 3회 반복 측정하여 평균값(mean)과 표준편차(standard deviation, SD)로 나타내었다. 연구 결과 총 polyphenol과 Tannin함량은 70%에탄올 추출물에서 $7.8{\pm}0.02mgGAE/g$, $9.9{\pm}0.01mgTAE/g$으로 열수 추출물보다 높은 함유량을 나타냈으며, DPPH radical의 소거능과 ABTS radical 소거능역시 70% 에탄올 추출물에서 농도가 10000 ppm일 때 각각 $46.1{\pm}4.76%$, $37.1{\pm}1.23%$로 열수 추출물보다 높게 나타났다. 항균효과에서는 C. albicans를 제외하고 모든 균에서 항균활성을 나타내었으며, 농도 25 mg/disc에서 E. coli는 $50^{\circ}C$ 열수추출물에서 $18{\pm}1.73mm$, S. epidermidis와 S. aureus는 70% 에탄올 추출물 에서 $17{\pm}4.36mm$, $19{\pm}2.86mm$로 열수추출물과 에탄올 추출물 모두 높은 항균력이 있음을 확인 하였다. 이와 같은 결과로 보았을 때 유자과즙추출물을 이용하여 비누, 샴푸 또는 두피개선제등 미용 또는 피부 관련 향장소재로서 활용할 수 있는 기초자료로서 충분한 가치가 있을 것으로 판단된다. This study analyzed the antioxidant activities and antibacterial effects of extracts from the fruit of Citrus junos. Theextracts were obtained in both 70% ethanol solution and distilled water at a distillation temperature of $50^{\circ}C$.Three experiments were carried out between November 2016 and March 2017. The averages and the standard deviations of the results were measured. The total polyphenol and tannin contents of the ethanol extracts were $7.8{\pm}0.02mgGAE/g$ and $9.9{\pm}0.01mgTAE/g$, respectively, which were higher than the concentrations in the water extracts. Furthermore, the ethanol extracts scavenged $46.1{\pm}4.76%$ of DPPH radicals and $37.1{\pm}1.23%$ of ABTS radicals. The scavenging capability of the ethanol extracts was also higher than that of the water extracts. However, the scavenging capability of both types of extracts depended on their concentrations.All the extracts showed active antibiosis effects against every bacteria tested except for C. albicans. E. coli at 25 mg/disc showed antibiosis with $18{\pm}1.73mm$ for the water extracts, while S. epidermidis and S. aureus showed antibiosis with $17{\pm}4.36mm$ and $19{\pm}2.86mm$ for the ethanol extracts, respectively. This antibiosis rate is considerably higher. The results suggest that fruit extract from Citrus junos could be useful as a primary material for beauty or skin-related products such as soaps, shampoos, and scalp enhancers.