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Effect of Plant Growth Regulators in In Vitro Culture of Hippophae rhamnoides
Songhee Lee,Wonwoo Cho,Hyeonsoo Jang,Romika Chandra,Sora Lee,Hoduck Kang 강원대학교 산림과학연구소 2021 Journal of Forest Science Vol.37 No.2
This study was carried out to establish in vitro propagation system influenced by plant growth regulators through organogenesis with three different seed sources (China, Mongolia and Russia) for conservation of genetic resources in Northeast Asia. The experiment compared two different carbon sources (commercial sugar, sucrose), which showed no significant differences in germination rate. Induced adventitious buds from leaf segments were found to be highly effective when supplemented with 1.0 mg/L BA, 1.0 mg/L Kinetin, and 5.0 mg/L IAA, in the case of Chinese origin 96.8%, Russian origin R-1: 95.6%, R-2: 85.6%, and Mongolian origin M-2: 77.8%. It was effective in BA and Kinetin with supplemented with IAA, respectively. Shooting development was also efficient in Woody Plant Media (WPM) supplemented with 1.0 mg/L BA, 1.0 mg/L Kinetin and 5.0 mg/L IAA.
Modeling of Transfer Region with Local Bond-Slip Relationships
Lee, Chadon,Lee, Songhee,Shin, Sangmin American Concrete Institute 2017 ACI structural journal Vol.114 No.1
<P>A theoretical model incorporating a rigid-linear local bond-slip relationship is presented to estimate axial displacements and strains of concrete and strands as well as slip and bond stresses along the span in a prismatic member. The effects of influential parameters on the local bond-slip relationship were identified from 92 transfer length test results. The validity of the developed model was then verified by its close predictions of the experimentally measured values from five beams tested in this study. Based on the developed model, an equation for the transfer length was suggested that considers the effect of concrete strength, prestress, strand diameter and its ratio, cover thickness, and type of release. The suggested equation predicted 92 experimentally measured transfer lengths better than other equations from different codes and literature. The overall average and standard deviation for the ratios of theoretical prediction to measured transfer length were 0.98 and 0.11, respectively.</P>
Songhee Lee,Wonwoo Cho,Romika Chandra,Jiwon Han,Hoduck Kang 강원대학교 산림과학연구소 2020 Journal of Forest Science Vol. No.
In this study, basic data with respect to the introduction of Hipphophae rhamnoides L. and its cultivation in Korea could be obtained. According to the size of the plug cell tray, Chinese origin’s rate of seed germination was relatively high in 128 plug cell tray, and growth was vibrant in 50 plug cell tray. The germination and growth of Russian origin seeds showed that they were relatively effective in 50 plug cell tray and with respect to soil environment, TKS-2 soil with untreated shading relatively promoted both germination and growth for Chinese origin, the rate of germination was high in bed soil for horticulture and growth result was good in TKS-2 in the case of Russian origin. It was confirmed that the germination rate of Chinese origin H. rahmnoides L. was highest in untreated shading and the shoot growth was vibrant in 70% shading while the growth in roots was vibrant in the untreated shading. In the Russian origin, H. rhamnoides L. the germination rate in 30% and 70% shading was about 50% which was higher than that in the untreated shading and general growth was vibrant in 30% shading.
Optimization of Curing Regimes for Precast Prestressed Members with Early-Strength Concrete
Songhee Lee,Ngocchien Nguyen,Thi Suong Le,Chadon Lee 한국콘크리트학회 2016 International Journal of Concrete Structures and M Vol.10 No.3
Early-strength-concrete (ESC) made of Type I cement with a high Blaine value of 500 ㎡/kg reaches approximately 60 % of its compressive strength in 1 day at ambient temperature. Based on the 210 compressive test results, a generalized rate-constant material model was presented to predict the development of compressive strengths of ESC at different equivalent ages (9, 12, 18, 24, 36, 100 and 168 h) and maximum temperatures (20, 30, 40, 50 and 60 °C) for design compressive strengths of 30, 40 and 50 MPa. The developed material model was used to find optimum curing regimes for precast prestressed members with ESC. The results indicated that depending on design compressive strength, conservatively 25–40 % savings could be realized for a total curing duration of 18 h with the maximum temperature of 60 °C, compared with those observed in a typical curing regime for concrete with Type I cement.
Raman Signatures of Polytypism in Molybdenum Disulfide
Lee, Jae-Ung,Kim, Kangwon,Han, Songhee,Ryu, Gyeong Hee,Lee, Zonghoon,Cheong, Hyeonsik American Chemical Society 2016 ACS NANO Vol.10 No.2
<P>Since the stacking order sensitively affects various physical properties of layered materials, accurate determination of the stacking order is important for studying the basic properties of these materials as well as for device applications. Because 2H-molybdenum disulfide (MoS2) is most common in nature, most studies so far have focused on 2H-MoS2. However, we found that the 2H, 3R, and mixed stacking sequences exist in few-layer MoS2 exfoliated from natural molybdenite crystals. The crystal structures are confirmed by HR-TEM measurements. The Raman signatures of different polytypes are investigated by using three different excitation energies that are nonresonant and resonant with A and C excitons, respectively. The low-frequency breathing and shear modes show distinct differences for each polytype, whereas the high-frequency intralayer modes show little difference. For resonant excitations at 1.96 and 2.81 eV, distinct features are observed that enable determination of the stacking order.</P>
Optimization of Curing Regimes for Precast Prestressed Members with Early-Strength Concrete
Lee, Songhee,Nguyen, Ngocchien,Le, Thi Suong,Lee, Chadon Korea Concrete Institute 2016 International Journal of Concrete Structures and M Vol.10 No.3
Early-strength-concrete (ESC) made of Type I cement with a high Blaine value of $500m^2/kg$ reaches approximately 60 % of its compressive strength in 1 day at ambient temperature. Based on the 210 compressive test results, a generalized rateconstant material model was presented to predict the development of compressive strengths of ESC at different equivalent ages (9, 12, 18, 24, 36, 100 and 168 h) and maximum temperatures (20, 30, 40, 50 and $60^{\circ}C$) for design compressive strengths of 30, 40 and 50 MPa. The developed material model was used to find optimum curing regimes for precast prestressed members with ESC. The results indicated that depending on design compressive strength, conservatively 25-40 % savings could be realized for a total curing duration of 18 h with the maximum temperature of $60^{\circ}C$, compared with those observed in a typical curing regime for concrete with Type I cement.
Lee, Hee Suk,Lee, Jeongyup,Yoon, Byengsuk,Yim, Youjin,Choi, Ilhwan,Cho, Hyukjin,Lee, Songhee,Baik, Kyounghee,Park, Ju Hyeon,Huh, Yu Jeong IWA Publishing 2013 WATER SCIENCE AND TECHNOLOGY -WATER SUPPLY- Vol.13 No.5
<P>Due to the tragic disaster that happened in Japan and crippled the Fukushima nuclear power plant, serious concerns have been raised regarding the contamination of drinking water as a result of the radioactive materials that were released. Even though the quantities of radioactive material in rain were relatively low, people were concerned about the drinking water. Therefore, there is a need to know the removal efficiency of the unit process of water treatment and to prepare a safety plan to protect the public's health from radioactive materials. In this study, the laboratory scale removal rates were estimated for the coagulation/flocculation, adsorption, and ion exchange processes. The reference standard materials which are stable elements, Cesium-133 (Cs-133) and Iodine-127 (I-127), were used for the typical and advanced water treatment processes at the laboratory scale. For the coagulation/flocculation process, three major coagulants were assessed for this process. However, the removal rates of this process were low. For the adsorption process, powdered activated carbon and zeolites were investigated. The powdered activated carbon showed insignificant removal rates for both reference materials. However, synthetic zeolite was an effective process for Cs-133, and the ion exchange method showed high removal rates for both Cs-133 and I-127.</P>