졸-겔 방법에 의한 $Li_2O-Al_2O_3-SiO_2$계 저열팽상성 결정화유리의 제조

양중식,김종범,양중식,Yang, Jung-Sik,Kim, Jong-Beom,Yang, Jung-Sik 한국재료학회 1993 한국재료학회지 Vol.3 No.3

$Li_2O-Al_2O_3-SiO_3$계 결정화유리의 저온합성을 위하여 출방원료로서 각 해당 금속 알콕시드를 사용하였다. 알코올을 용매로 충분히 첨가하고, drying control chemical additive로 dimethy1 formamide를 적당량 첨가한 혼합용용액을 과잉의 물로 충분히 가수분해시킨 습윤겔을 저온으로 건고하여 균열이 없는 건조된 monolith겔을 합성하였다. 건조겔로부터 750-$950^{\circ}C$로 10시간 이상 소결하여 저열팽창성을 나타내는 ${\beta}$-eucrypytite(${\beta}$-quartz 고용체), $Li_2O\cdot Al_2O_3\cdot 3SiO_2$및 ${\beta}$-spodumene등의결정상을 석출시켰다. Glass-ceramic monoliths with an ultra-low thermal expansion coefficient have been synthesized by the sol-gel technique using metal alkoxides as starting materials and dimethyl formamide as a drying control chemical additive. The ternary gels: $Li_2O\cdot Al_2O_3\cdot 2, 4 or $6SiO_2$ were obtained by hydrolysis and polycondensation reactions of metal alkoxides of silicon, aluminum and lithium. To produce cylindrical crack-free gel monoliths, excess water was used to the starting solutions and drying rates were controlled precisely to prevent cracking. In conversion process ,${\beta}$-eucryptite, $Li_2O\cdot Al_2O_3\cdot 3SiO_2$ and P-spodumene with ,${\beta}$-quartz solid solution phase were obtained by heating at the range of 750 ~$1000^{\circ}C$. Above $800^{\circ}C$, the ,${\beta}$-spodumene phase increased while ,${\beta}$-eucryptite phase decreased. The thermal expansion coefficient of the crystallized specimens were -15~ $+5{\times}{10^{-7}}/{\circ}C$ over the temperature range from room temperature to $600^{\circ}C$.

금속 알콕시드를 이용한 투명 결정화유리의 저온 합성 : (2) Li_(2)O·1.7Al_(2)O_(3)·8.6SiO_(2) 다공성 겔체로부터 투명 결정화 유리의 합성 (2) Conversion of Gel in Li_(2)O·1.7Al_(2)O_(3)·8.6SiO_(2) to Transparent Glass-Ceramic Monoliths and their Properties

양중식 경희대학교 자연과학종합연구원 2001 자연과학논문집 Vol.7 No.-

L_(12)O·1.7Al_(2)O_(3)·8.6S_(1)O_(2)(mol)조성의 균열이 없는 건조 괴상겔체를 졸-겔방법으로 제조하여 이를 열 처리하여 나노 크기로 결정화 시켜서 투명한 결정화 유리를 합성하였다. 열시차분석에 의하면 1차 발열 peak는 800℃, 2차는 980℃ 부근에서 확인되었다. X-선 회절분석결과 800∼820℃에서 열처리한 시료의 생성결정 광물은 β-quartz 고용체(solid solution) 결정상인 virgilite로서 투명하였고, 900℃ 이상에서는 β-spodumene과 quart 고용체임이 확인되었다. 투명결정화를 위한 활성화에너지는 100.9㎉/㏖이었다. 800∼820℃에서 열처리한 시료의 기공부피, 크기분포 및 결정크기가 각각 0.000053㏄/g, 0.2∼7.5㎚, 5㎚이하이고, 투과율 80% 이상의 투명결정화유리로 확인되었다. 투명결정화유리의 열팽창계수는 60∼860℃까지는 -1.2×10^(-7)/℃로 (-)값을 나타냈다. Crack-free dried gel monoliths with a composition Li_(2)Oㆍ1.7AI_(2)O_(3)ㆍ8.6SiO_(2) have been prepared as a precursor of transparent glass-ceramic by the sol-gel technique using metal alkoxides as starting materials to obtain monolithic nano-crystallized glass-ceramics at low temperature without melting. As a result of the analysis of DTA and XRD it was confirmed that the first exothermic peak around 800℃ and the 2nd peak around 980℃, which may correspond to crystallization of the gel. Transparent virgilite with β-quartz solid solution crystals were detected in the gel heat treated around 800 ℃ β-eucryptite with β-quartz solid solution, and β-spodumene with β -quartz solid solution were detect-ed in the sample heat treated above 900℃. The crystallized gel heat treated at 800℃ had the pore volume of 0.000053cc/g, the pore diameter of 0.2∼12nm and the crystallized particles are smaller size than 5nm. In temperature range of 60∼860℃ thermal expansion coefficient of the specimen which was crystallized for 8hrs at 800℃ was -12×10^(-7)/℃ which indicated that the crystallized specimen was turned out to be the transparent glass-ceramic with low thermal shrinkage.

건자재용 저온-고효율 원적외선 복사재료의 연구

양중식 慶熙大學校 材料科學技術硏究所 1996 材料科學技術硏究論集 Vol.9 No.-

The purpose of this study is to develop the radiators using construction materials in the long wavelenghs such as the far IR at low temperatures. In order to extend to emissivity range of the far IR of the materials and also improve the radiation properties of ceramic substances. The radiants for far IR radiation which are on use in the domestic buildings are investig-ated, and these characteristic values are compared with each other. The conditions for the proper mixed ratio of inorganic cements and ceramic materials of silicate system were added as the binding agents such as portland cements and alumina gel. The results obtained are summarized as follows; Emission properties of the sintered clay specimen by penetrating of carbon black and transitional metals at 900℃ for 2 hours was obtained higher than using cements, basalt and silicon carbide main materials and addition of powdered glass, CuO and MnO_(2) ingredients as active materials.

다봉분포 면섬유 특성과 방적사의 물성에 관한 연구(l) -섬유 물성의 대표값 결정-

양중식,강태진 한국섬유공학회 1998 한국섬유공학회지 Vol.35 No.5

The nature of multimodal distribution of fiber length, fineness and bundle strength of the fiber mixture as a result of mixing fiber assemblies differing in fiber properties and mixing ratio has been studied. The representative values of the fiber properties, such as mean fiber length, fiber length variance and short fiber content by number and by weight, respectively, micronaire and bundle strength of the fiber mixture showing multimodal distribution have been determined from those of individual fiber assembly by the mixing rule of fiber properties. The results show that the mean fiber length, fiber length variance and short fiber content, by number or by weight, of the fiber mixture showing bimodal distribution were very close to those derived from the fiber properties of the individual fiber assembly and its number proportion or weight proportion, respectively. The mean fiber fineness of the mixture was very close to the value derived from mean fiber fineness of the individual fiber assembly and its weight proportion. The mean bundle strength of the fiber mixture measured with High Volume Instrument showed higher value by 4.5% to 12.0% than weighted mean value of bundle strength calculated from the mean bundle strength of individual fiber assembly and its weight proportion.

분양가 자율화와 건설회사의 주가

양중식 한국건설관리학회 2019 한국건설관리학회 논문집 Vol.20 No.5

This study is designed to examine the stock price of construction firms which are affected by the deregulation of new apartment sales price. As empirical methodology, it uses the traditional event study analysis to test the influence of the deregulation of new apartment sales price and the regression analysis to test which variables are related. The results of this study are summarized as follows : First, the cumulative abnormal return of stock is positive when government announced the deregulation of new apartment sales price. The cumulative abnormal return of stock for 21 trading day before –10 to +10 day is 25.51% which is significant different from zero at 1 percent level. This result suggests that the deregulation of new apartment sales price conveys good information to stock market that the firms performance will be good in the future. Second, in the regression analysis this study shows that the cumulative abnormal return of stock is related to firm’s profit margin ratio.

다봉분포 면섬유 특성과 방적사의 물성에 관한 연구(II) -1 베일 및 40 베일 방적 실험-

양중식,강태진 한국섬유공학회 1999 한국섬유공학회지 Vol.36 No.1

The effects of fiber characteristics such as fiber length, fineness, and bundle strength in the cotton fiber mixture of multimodal distribution on the properties of ring spun cotton yarn have been studied. The relationship between the fiber properties including fiber quality index and the yarn properties including yarn quality index has been studied by mill spinning experiments using 1 bale and 40 bales differing in weight proportion and in fiber properties of the individual bales. Multiple linear regression analysis of the relationship between the fiber properties and the cotton spun yarn properties produced from mill scale experiments showed that strength, elongation, toughness index, and yarn quality index of spun yarn increased with fiber quality index, but that the irregularity of spun yarn decreased with fiber quality index. In addition, it showed that there was no significant relationship between the fiber quality index and the stiffness index of the spun yarn. The determination coefficients of the multiple linear regression equations between fiber properties and yarn properties such as lea strength and count strength product are larger than those of the multiple linear regression equations between fiber properties and yarn properties such as single yarn strength and tenacity.

Sol-Gel법에 의한 Li2O-Al2O3-SiO2계 괴상겔 및 결정화유리의 합성

양중식,작화제부 한국세라믹학회 1988 한국세라믹학회지 Vol.25 No.5

The purpose of this investigation was to prepare multicomponent monolithic Li-Al-Si gels of composition(mol%) 16.67 Li2O-16.67 Al2O3-66.67 SiO2 and to convert the gels to monolithic glass-ceramic at low temperature without melting. The hydrolysis, DTA, TGA, TMA, SEM, pore distribution, density and the activation energy for crystallization of the glass-ceramic formation with rawmaterials of which tetraethl orhosilicate of networkforming cation(Si) is partially hydrolyzed, aluminum isoproxide and lithium methoxide prepared by Li-metal react with methanol were studied. The results were as follows : 1) Monolithic gels which were added with additional water, resulting in a total water content 2.5 to 3.0 times the stoichiometric amount required to fully hydrolyze the alkoxides. 2) Specimens were dried to form crylinders 60mm in length and 40mm in diameter in about 800 hrs at 5$0^{\circ}C$. 3) $\beta$-eucryptite crystals and $\beta$-spodumene crystals were detected in samples heated above 75$0^{\circ}C$. 4) Within the temperature and range of 25-50$0^{\circ}C$ and 1,00$0^{\circ}C$ the thermal expansion coefficient for crystallized samples were shown as 2.6-5.7$\times$10-7/$^{\circ}C$ and 7.4-12.5$\times$10-7/$^{\circ}C$, respectively. 5) The activation energy for the crystal growth was 11.01kcal/mol at 794$^{\circ}C$ to 85$0^{\circ}C$.

원적외선의 비열효과와 수소결합의 배향

양중식,Yang, Jung-Sik (사)한국원적외선협회 2000 한국원적외선협회보 Vol.5 No.-

이온선택성 전극을 이용한 콘크리트 중의 가용성 염화물 이온의 전위차 적정

양중식 경희대학교 산학협력기술연구원 1999 산학협력기술연구논문집 Vol.5 No.-

A Water-soluble chloride in concrete has been titrated potentiometrically with silver nitrate as a reagent and used a silver/Sulfide ion-selective electrode as an indicator. By the use of a standard substraction method the experimental detection limit war ~1ppm at th S/N~6 and Silver/Sulfide ion--selective electrode responded in a linear manner to chloride over a wide range of concentration. Although solubility depends on the leaching temperature, we set the leaching temperature at 50℃ for the reason that the maximum temperature of building surface is 50℃ in summer. When the ratio of sample to the amount of leaching water was 1/5 to 1/10, it showed that the leaching ratio of chloride was reproducible result To improve th accuracy, it is very important to fix the ratio of sample to the amount of leaching water. In this study, the amount of water-soluble chloride was raised depending on the leaching time. Over th leaching time of 40minutes the slope of chloride vs. leaching time was constant. Accordingly it is considered that suitable leaching time is 40minutes.

개질 고로 슬래그에 관한 연구 (유리 제조에 관한 연구)

양중식 한국세라믹학회 1981 한국세라믹학회지 Vol.18 No.2

A study was made on the processing of domestic blast furnace slag by flotation and chemical purification for the use of slag as a raw material in making soda lime glasses. Feasibility study has been made for the use of reprocessing slag as a source material for both coloring and chemical components (such as CaO, $Al_2O_3$, MgO and etc.) in the glass making process. Chemical composition of chemically purified slags ranges; $SiO_2$ 34.5~37.5, $Al_2O_3$, 16.2~14.1, $Fe_2O_3$ 0.33~0.14, CaO 34.5~38.8, MgO 4.0~5.2, NmO 0.16~0.39, $TiO_2$</TEx> 0.23~0.35, S 0.08~0.42, ignition loss 3.3~8.4 and others 0.48~0.51%. It was found that either amber or greenish color could be easily obtained with the addition of salg up to 24%, however the slag addition to glass batches much impaired the transmitancy of glass products, thus a glass made with 7% slag addition showed 82% in transmitancy value at 510 nm.