액체 An-In, Al-Sn, Al-Ga 계합금의 열역학적 성질

이용근 대한금속재료학회(대한금속학회) 1970 대한금속·재료학회지 Vol.8 No.2

金屬溶液의 熱力學的性質은 冶金理論의 基礎를 이루우고 있으므로, Al冶金의 基礎的硏究로서, 液體 Al溶液의 熱力學的 硏究를 한 結果中에서 Al-In, Al-Sn 및 Al-Ga系에 대한 特性을 論한다. 濃淡電地에 의한 그 起電力을 全組成範圍에 선하여 各各 700℃에서 94℃, 680℃에서 860℃ 및 680℃에서 820℃의 溫度範團에서 測定하고, 이것에 의거하여 Al, In, Sn 및 Ga의 各系에 있어서의 活量과 다른 熱力學的性質을 算出하여, 그 結果를 考察하였다. 이 中에서 Al-In系에는 二液相이 있어서 그 範圍을 起電力의 測定値에서 決定하였다. Al-In系의 成分의 活量은 Raoult의 法則에서 크게 正으로 偏倚하고, 溫度가 높을 수록 Raoult의 法則에 接近하여, 二液相內에서는 組成에 關係 없이 定溫度에서는 일정한 活量을 나타낸다. Al-Sn系에서는 Raoult의 法則에서 상당히 正으로 偏倚하며, Al-Ga系에서는 상당히 잘 따르고 있다. 그리하여 Al-In系는 比正則溶液, Al-Sn系는 sub-regular solution 및 Al-Ga系는 regular solution에 가까움을 알 수 있었다. 이 系들의 無限稀溥溶液에서의 活量係數는 γ˚은 Al-In系는 700℃에서 Al, In 各各 11.3, 13.2이며, Al-Sn系에서는 800℃에서 各各 4.05, 7, 11 및 Al-Ga系에서는 700℃에서 各各 1.15, 1.27을 얻었다. 한편 統計熱力學으로도 model 을 適用하여, 古典熱力學에 의한 結果와 比較考察하였다. 즉 Al-In系에 대해서는 model과 二液相境界線을 써서 活量을 算出하고, Al-Sn, Al-Ga의 兩系에 대해서는 各系의 熱力學的 過剩量을 算出하였다. 그리고 quasi-chemical의 近似式을 써서 3系에 있어서의 原子相互作用 energy와 short-range order parameter를 算出하고, 또 3系에 있어서의 各成分間의 self-interaction parameter도 算出해서, 이것들의 系의 巨視的性質과 微視的性質을 比較考察하여 서로 一致함을 알았다.

熔融알루미늄 二元合金의 混合熱

李容根 全北大學校 1976 論文集 Vol.18 No.-

The heats of mixing in the binary liquid aluminum alloys, Al-In, Al-Ga and Al-Ge systems were determined using an adiabatic calorimeter directly, and those of Al-Sn, Al-Zn, Al-Te and Al-Au systems were also determined by the electromotive force method, dew point method and distribution method indirectly. The values obtained were treated with ξ function^2), and the properties of these solutions have been observed based on the ξ functhons. As a result, it seems that Al-Zn system is a regular solution, Al-Ga, a regular soluton obeying quasi-chemical approach and Al-Ge, a sub-regular solution. The relations of the ξ function to the periodic law and to the equilibrium diagram in each system were discussed, and the short-range order parameters have also been derived using the heats of mixing in the Al-In and Al-Ga systems.

중국 전자상거래시장의 현황과 향후전망

이용근,김창봉,김시중,박경희 중앙대학교 한국전자무역연구소 2008 전자무역연구 Vol.6 No.2

중국 전자상거래 시장은 정보화 인프라, 지급시스템, 물류체계, 유능한 인적 자원 부족뿐만 아니라 정보인프라 미비, 법적 그리고 규율적 체계부족과 전자상거래 신뢰부족 등과 같은 아주 많은 문제점을 안고 있다. 소규모 B2B 서비스가 수년내에 인수합병을 경험하게 될 것이지만 B2B시장은 보안인증시스템에서 빠른 성장을 보여줄 것으로 예측되고 있다. B2C 시장은 큰 성장을 보여주지는 못할 것이고 C2C시장은 추가적인 성장을 달성하고 C2C 고객에게 서비스를 제공하는 비즈니스 모델은 앞으로 중요한 수입원이 될 것이다. 본 논문의 목적은 중국 전자상거래 시장에 진출하고자 하는 기업들에게 도움이 되고자 하는 것이다.

Novel Calcium Phosphate Glass for Hard-Tissue Regeneration

이용근,최성호 대한치주과학회 2008 Journal of Periodontal & Implant Science Vol.38 No.2

Purpose: The aim of this review is to introduce a novel bone-graft material for hard-tissue regeneration based on the calcium phosphate glass(CPG). Materials and Methods: CPG was synthesized by melting and subsequent quenching process in the system of CaO-CaF2-P2O5-MgO-ZnO having a much lower Ca/P ratio than that of conventional calcium phosphates such as HA or TCP. The biodegradability and bioactivity were performed. Effects on the proliferation, calcification and mineralization of osteoblast-like cells were examined in vitro. Influence in new bone and cementum formations was investigated in vivo using calvarial defects of Sprague-Dawley rats as well as 1-wall intrabony defect of beagle dogs. The application to the tissue-engineered macroporous scaffold and in vitro and in vivo tests was explored. Results: The extent of dissolution decreased with increasing Ca/P ratio. Exposure to either simulated body fluid or fetal bovine serum caused precipitation on the surface. The calcification and mineralization of osteoblast-like cells were enhanced by CPG. CPG promoted new bone and cementum formation in the calvarial defect of Sprague-Dawley rats after 8 weeks. The macroporous scaffolds can be fabricated with 500~800μm of pore size and a three-dimensionally interconnected open pore system. The stem cells were seeded continuously proliferated in CPG scaffold. Extracellular matrix and the osteocalcin were observed at the 2nd days and 4th week. A significant difference in new bone and cementum formations was observed in vivo (p<0.05). Conclusion: The novel calcium phosphate glass may play an integral role as potential biomaterial for regeneration of new bone and cementum. (J Korean Acad Periodontol 2008;38:273-298) Purpose: The aim of this review is to introduce a novel bone-graft material for hard-tissue regeneration based on the calcium phosphate glass(CPG). Materials and Methods: CPG was synthesized by melting and subsequent quenching process in the system of CaO-CaF2-P2O5-MgO-ZnO having a much lower Ca/P ratio than that of conventional calcium phosphates such as HA or TCP. The biodegradability and bioactivity were performed. Effects on the proliferation, calcification and mineralization of osteoblast-like cells were examined in vitro. Influence in new bone and cementum formations was investigated in vivo using calvarial defects of Sprague-Dawley rats as well as 1-wall intrabony defect of beagle dogs. The application to the tissue-engineered macroporous scaffold and in vitro and in vivo tests was explored. Results: The extent of dissolution decreased with increasing Ca/P ratio. Exposure to either simulated body fluid or fetal bovine serum caused precipitation on the surface. The calcification and mineralization of osteoblast-like cells were enhanced by CPG. CPG promoted new bone and cementum formation in the calvarial defect of Sprague-Dawley rats after 8 weeks. The macroporous scaffolds can be fabricated with 500~800μm of pore size and a three-dimensionally interconnected open pore system. The stem cells were seeded continuously proliferated in CPG scaffold. Extracellular matrix and the osteocalcin were observed at the 2nd days and 4th week. A significant difference in new bone and cementum formations was observed in vivo (p<0.05). Conclusion: The novel calcium phosphate glass may play an integral role as potential biomaterial for regeneration of new bone and cementum. (J Korean Acad Periodontol 2008;38:273-298)

레진강화형 글라스아이오노머의 2 축 굽힘강도

이용근,임미경,구대회,이정식 大韓齒科保存學會 1997 Restorative Dentistry & Endodontics Vol.22 No.2

Resin-modified glass ionomers were introduced in 1988 to overcome the problems of moisture sensitivity and low early mechanical strengths of the conventional glass ionomers, and to maintain their clinical advantages. The purpose of this study was to evaluate the bi-axial fracture strength of four resin-modified glass-ionomers(Fuji II LC, Vitremer, Dyract, VstiGlass), one resin composite material(Z-100), and one conventional glass-ionomer(Fuji II). Three specimens of each material and shade combination were made according to the manufacturers' instructions. Materials were condensed into metal mold with a diameter of 10mm and a thickness of 2.0mm and pressed between two glass plates. Resin-modified glass ionomers were polymerized using a Visilux II light curing unit by irradiating for 60 seconds from both sides, and conventional glass ionomer was cured chemically. After specimens were removed from the molds, surfaces were polished sequentially on wet sandpapers up to No. 699 silicone carbide paper. The specimens were thermocycled for 2,000 cycles between 5℃ and 55℃ distilled water. After thermocycling, bi-axial fracture strengths were measured using a compressive-tensile tester(Zwick 1456 Z020, Germany) with the cross head speed of 0.5mm/minute. The results were as follows: 1. Two factors of the kind and color of materials had a main effect on bi-axial fracture strength (p<0.01), and bi-axial fracture strength was influenced significantly by the kinds of materials (p<0.01). But there was no significant interaction between two variables of the kind and color of materials (p>0.05). 2. Comparing the mechanical properties of the materials, the elastic modulus of Z100 was higher than any other material, and there was no difference in the displacement at fracture among materials. The bi-axial fracture strength of Z100 was significantly higher than any other material, and that of resin-modified glass ionomers was significantly higher than that of conventional glass ionomer (p<0.05). 3. In the same material group, the color of material had little influence on the mechanical properties.

치아미백제에 의한 치과 수복재의 특성변화에 관한 연구

이용근 대한치과기재학회 1996 대한치과재료학회지 Vol.23 No.2

Tooth whiteners are used widely to recover the original color of tooth. There is no doubt these products work as whiteners, at least on mild to moderate stains, but the safety of these products are unclear. Abrasive agents in the tooth whitener remove attached stains on the tooth surface or bleaching agents in the tooth whitener change the organic material within the tooth. Free radicals released from tooth whiteners can change the surface properties including color of restorative materials or can accelerate the corrosion of dental appliances made of metal. In this experiment, the effect of tooth whitener application on the color and microhardness of seven esthetic restorative materials was determined in vitro. RMS, NWT and MTD were used as tooth whiteners and tooth paste(DTQ) was used as control. Specimens were made according to the manufacturer's instructions and were polished. Initial color and Vickers hardness were measured. The tooth whiteners and control agents were applied according to the manufacturers' instructions or clinically simulated procedures for eight weeks. Color difference was measured using Differential Colorimeter(Model TC-6FX, Denshoku Co. Japan), and microhardness was measured using microhardness tester (Mitsuzawa Seiki Co. Japan). The results of CIELAB L*, CIELAB ΔE* and Vickers hardness were analyzed. The results were as follows; 1. CIELAB L* values after tooth whitener application were changed significantly depending on three variables, those were material type, tooth whitener type and application period(p<0.01). Five kinds of materials showed the highest CIELAB L* values after RMT application, but the difference of values among the materials was small. 2. DTQ applied group showed the smallest color difference (CIELAB ΔE* value) after application for four or eight weeks, and NWT applied group showed the highest color difference during first four week period. MTD applied group showed the highest color difference during four to eight week period, and resultantly showed the highest color difference after eight week application. 3. Vickers hardness numbers were generally increased after whitener application. In the same material, the change ratios of VHNs were not different regardless of the applied agents, and VHNs of glass ionomers were increased significantly higher than those of composite resins.

信用狀 詐欺에 대한 Fraud Rule 適用의 問題點과 對應方案에 관한 硏究

李鎔根,韓載泌 中央大學校 1996 國際貿易硏究論叢 Vol.3 No.-

백서 패혈증 모델에서 HSP70의 과도 발현이 iNOS의 발현에 미치는 효과에 관한 연구

이용근,안융,임대호,백진아,고승오,신효근,Lee, Yong-Keun,Ahn, Yung,Leem, Dae-Ho,Baek, Jin-A,Ko, Seung-O,Shin, Hyo-Keun 대한구강악안면외과학회 2010 대한구강악안면외과학회지 Vol.36 No.5

Introduction: Heat shock protein70 (HSP70) is a highly conserved family of proteins produced after a variety of stresses. Many studies reported that the overexpression of HSP70 can improve the prognosis of the patients with sepsis through a reduction of the nitric oxide concentration. However, these results only revealed the effect of HSP70 and nitric oxide. No studies have examined the relationship between HSP70 and nitric oxide. The aim of this study was to evaluate the effect of the overexpression of HSP70 on the expression of inducible nitric oxide synthase and the nitric oxide concentration. In addition, the mechanism of the relationship of HSP70 and inducible nitric oxide synthase (iNOS) in sepsis was examined. Materials and Methods: The experiments were performed on male sprague-dawley rats. Sepsis was induced by a cecal ligation and puncture (CLP). Glutamine (GLN) or saline was administered 1 hour after the initiation of sepsis. Serum and lung tissues were acquired from the rats 12 hours or 24 hours after the initiation of sepsis. The nitric oxide concentration, the expression of HSP70 in lung, and the gene expression of iNOS in lung were analyzed. The three groups, sham operation, CLP and CLP+GLN, were compared. Results: Compared to the other groups, in CLP+GLN, GLN administered after the initiation of sepsis enhanced the expression of HSP70 in the lung at 12 hours ($47.19{\pm}10.04$ vs. $33.22{\pm}8.28$, P=0.025) and 24 hours ($47.06{\pm}10.60$ vs. $31.90{\pm}4.83$, P=0.004). In CLP+GLN, GLN attenuated the expression of iNOS messenger RNA (mRNA) in the lung at 12 hours ($5,513.73{\pm}1,051.60$ vs. $4,167.17{\pm}951.59$, P=0.025) and 24 hours ($18,740.27{\pm}8,241.20$ vs. $9,437.65{\pm}2,521.07$, P=0.016), and reduced the concentration of nitric oxide in the serum at 12 hours ($0.86{\pm}0.48$ vs. $3.82{\pm}2.53$, P=0.016) and 24 hours ($0.39{\pm}0.25$ vs. $1.85{\pm}1.70$, P=0.025). Conclusion: The overexpression of HSP70 induced by the administration of GLN in sepsis attenuates the expression of the iNOS gene but reduces the nitric oxide concentration.

液體 Al-Zn, Al-Te系의 熱力學的 性質

李容根 全北大學校 1971 論文集 Vol.13 No.-

The liquid aluminum-zinc and -tellurium systems have been investigated by the dew point method for clarifying their thermodynamic properties. In this work, the dew point method has been improved so as to find out the dew point thermoanalytically and record it automatically. Consequently, the measuring operation is simpler, and that, the result is more accurate than that of ordinary one. The measurements were carried out over entire composition range for both systems, and in the temperature range 650°to 800℃ for the Al-Zn system and 700°to 920℃ for the Al-Te system. The activities of the components Al, Zn and Te of both systems have been derived using the messured data, and also calculated from quasichemical approach, regular solution theory and the heat of fusion of Al_2 Te_3. The interaction energies and short-range order parameters for the Al-Zn system have been calculated from quasichemical approach and the results are reasonable to compare with the classical thermodynamic properties.

교정용 선재와 브라켓 사이의 마찰력에 관한 연구

김철위,박영준,이용근 大韓齒科器材學會 1995 대한치과재료학회지 Vol.22 No.2

Mechanical friction makes the orthodontic tooth movement require greater force than the biological tooth movement. Friction is affected by the size, shape, and material of both the bracket and the wire. This study was designed to investigate the effect of material or size of orthodontic brackets and orthodontic wires on the amount of frictional forces generated during simulated tooth movement. A testing apparatus was designed to simulate the clinical situation in which the center of resistance of a tooth is not on the same plane as that of bracket, thereby resulting in some tipping of the bracket slot relative to orthodontic wire (100 gram weight was suspended). In angulated and non-angulated experimental condition, the orthodontic wires were drawn through the testing apparatus with the speed of 2mm/minute. The results were as follows : 1. In both of the cases of the metal bracket and ceramic bracket, the frictional forces were greater in angulated experimental group than non-angulated group. In both of the non-angulated and angulated experimental group, the frictional forces of ceramic brackets were greater than those of metal brackets. In most of cases, these differences were statistically significant(p<0.05) with a few exceptions. 2. In general, the frictional forces of orthodontic wires with circular cross-cut surface were lower than those wires with rectangular cross-cut surfaces. But there was no statistically significant correlation between the size of orthodontic wire and frictional forces. 3. There was no difference between the frictional of the stainless-steel orthodontic wires and those of the cobalt-chromium orthodontic wires, but the frictional forces varied depending on the measuring condition or brand of the wires. 4. The frictional forces of β-titanium orthodontic wires were significantly higher than those of stainless-steel orthodontic wires were cobalt-chromium orthodontic wires.