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Photoluminescence과 Conductance 측정을 이용한 자외선 조사된 Ge첨가 다성분계 산화물 유리의 구조변화 관찰
이회관,오영석,강원호 단국대학교 2001 산업기술연구 Vol.2 No.-
Ge-doped multicomponent oxide glasses were prepared by a conventional melting method. The structural change around Ge ions was investigated by using PL(photoluminescence) and conductance(G). After UV irrdiation, the PL intensity decreased and the change were maintained at room temperature, but a photodarkened glass recovered near its original properties when it was heat-treated at 500℃ for several hours. The conductance of the irradiated sample decreased because the disorder in structure was happened by UV irradiation. These results can be explained a structural change were occurred at bonding structure between Ge ions and glass components.
Microwave Effect on Curing of Waterborne Polyurethane
Lee, Hoi-Kwan,Fang, Chris. Y.,Pantano, Carlo. G.,Kang, Won-Ho Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.3
Spin-coated waterborne polyurethane to protect glass surface from environmental attacks was cured by using microwave heating. The effect of microwave heating on the reaction kinetics, chemical durability, and transmittance of polyurethane was investigated. In comparison to the conventional heating the results show that the microwave heating substantially accelerates the curing process of waterborne polyurethane and the total time for the completion of the reaction is only 1/7 of that in the conventional process. The microwave cured sample showed an excellent caustic resistance compared to conventional cured one. It means that microwave heating produces dense structure during curing process. The dense structure does not affect to the transmittance in the visible region.
Dissolution Properties of Phosphate Glasses with Trace Elements
Lee, Hoi-Kwan,Kang, Won-Ho The Korean Ceramic Society 2005 한국세라믹학회지 Vol.42 No.6
Phosphate glasses were prepared by melting quenching process, and glass formation and dissolution properties were studied. The glass forming region in the $K_2O-CaO-P_2O_5$ system is quietly agreed with the report by Mazurin OV et al. with $M_2O-M'O-P_2O_5$ system (M : monovalent cation, M'divalent cation). Conditionally these glasses have solubility from absorbing the moisture or water and then release elements with trace elements, and the thermal and chemical properties were controllable by the $CaO,\;K_2O,\;P_2O_5$ contents. In the abnormal glass properties, this paper showed the possibility the present glasses can be a good candidate for one component of the slow released agriculture fertilizer.
Preparation and Dissolution Properties of the Eco-glass Fertilizer containing Trace Elements
Hoi Kwan Lee,Sheng Jean Hwang,Won Ho Kang 한국산학기술학회 2004 한국산학기술학회 학술대회 Vol.- No.-
At the previous papers, we showed that K<sub>2</sub>O-CaO-P<sub>2</sub>O<sub>5</sub> glasses had a solubility in air so that they could be used for glass fertilizer. In this work, we fabricated the Eco-glass fertilizer containing trace elements such as B, Mg, Zn, Fe, Cu, Co, and Mo by a melt-quenching process and the dissolution properties of these glasses were investigated with pH meter and ICP analyzer. In case of the glasses containing the trace elements, effect of trace elements on the dissolutions is not obvious and ignorant the stability of mother glass. Also, the dissolution amounts of each trace elements depend on the mother glass composition and the quantity of each trace element, and mother glasses determined the dissolving velocity of chemical elements
Dissolution Properties of Phospate Glasses with Trace Elements
Hoi-Kwan Lee,강원호 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.6
Phosphate glasses were prepared by melting quenching process, and glass formation and dissolution properties were studied. The glass forming region in the K2O-CaO-P2O5 system is quietly agreed with the report by Mazurin OV et al. with M2O-MO- P2O5 system (M : monovalent cation, Mdivalent cation). Conditionally these glasses have solubility from absorbing the moisture or water and then release elements with trace elements, and the thermal and chemical properties were controllable by the CaO, K2O, P2O5 contents. In the abnormal glass properties, this paper showed the possibility the present glasses can be a good candidate for one component of the slow released agriculture fertilizer..
Microwave-assisted Sintering of Amorphous Powders
Lee, Hoi-Kwan,Kim, Ki-Min,Park, Man-Kyu,Kang, Won-Ho The Korean Ceramic Society 2011 한국세라믹학회지 Vol.48 No.1
Microwave heating (MW) was studied for the sintering of amorphous powders. In comparison to conventional heating (CV), the results show that microwave heating has the potential to substantially accelerate the sintering process and allow for highly densified solidification by eliminating the pores and increasing the shrinkage rate. In the heat treatment to synthesize aluminum borate ($Al_{18}B_4O_{33}$) whiskers from precursors, it was found that microwave heating helps the formation of $Al_{18}B_4O_{33}$ crystal as well as the decrease of crystallization temperature of $Al_{18}B_4O_{33}$ to a level significantly lower than the previously reported value of $1050^{\circ}C$.
Improvement of Mechanical Property by Single Ion Exchange Process in Substrate Glass
Lee, Hoi-Kwan,Kang, Won-Ho,Green, David J. The Korean Infomation Display Society 2003 Journal of information display Vol.4 No.3
In connection with the ion exchange strengthening on soda-lime-silicate, substrate glass for display use was investigated. In the processing, the temperature was varied during the ion exchange in order to make stress profile and to determine optimum condition. In the present work, we found that the maximum value of strength was 617.8 MPa after an ion exchange process at 470 $^{\circ}C$ for 1h, and then, at 450 $^{\circ}C$ for 24h. Also, the effect of residual stress placed on the near surface was measured by analyzing the number of crack branches and brittleness. This approach allowed us the residual stress profile to be engineered to improve mechanical reliability.
이회관(Lee, Hoi-Kwan),강원호(Kang, Won-Ho) 한국산학기술학회 2005 한국산학기술학회논문지 Vol.6 No.2
앞선 논문에서 K<sub>2</sub>O-CaO-P<sub>2</sub>O₅유리의 용출 특성을 이용한 유리질 비료로서의 가능성을 보고한바 있으며, 본 연구에서는 K<sub>2</sub>O-CaO-P<sub>2</sub>O₅ 조성에 식물의 성장에 필요한 미량원소인 B, Mg, Zn, Fe, Cu, Co, Mo을 첨가한 유리를 제조하였으며, 제조된 유리의 용출 특성을 pH와 ICP 분석을 통하여 관찰하였다. 미량원소가 첨가된 유리의 경우 첨가전의 pH값의 변화와 차이가 없었으며, 모유리의 안정화에 영향을 미치지 못함을 알 수 있었다. 첨가된 미량원소의 용출량은 모유리조성과 첨가된 함량에 비례하였으며, 이러한 원소들의 용출속도는 모유리 조성에 의하여 결정되었다. At the previous papers, we showed that K<sub>2</sub>O-CaO-P<sub>2</sub>O₅ glasses had a solubility in air so that they could be used for glass fertilizer. In this work, we fabricated the Eco-glass fertilizer containing trace elements of B, Mg, Zn, Fe, Cu, Co, Mo, the needed micronutrients for plants to grow, by a melt-quenching process. The dissolution properties in these glasses were investigated with a pH meter and an ICP analyzer. The trace elements doped glassesshowed similar behavior in dissolutions and stability properties with the mother glass without containing trace elements. In addition, the dissolution amount of each trace elements depends on the mother glass composition and the quantity of each trace elements. which determine the dissolvina velocitv of chemical elements.