• 전자공학회논문지A
• /
• 제29A권9호
• /
• pp.20-28
• /
• 1992

Dielectric thin film of N/O ($Si_{3]N_{4}/SiO_{2}$) for high density stacked dynamic-RAM cell was formed by LPCVD and oxidation(dry & pyrogenic oxidation methods) of the top 7nm $Si_{3]N_{4}$ film. The thickness, structure and composition of this film were measured by ellipsometer, high resolution TEM, AES and SIMS. The insulating characteristics(I-V characteristics) were investigated by HP 4145, and the characteristics of TDDB (Time Dependent Dielectric Breakdown) were evaluated by using CCST(Current Constant Stress Time) method. In this experiment, The optimum oxidation condition for preparation of good insulating and TDDB characteristics of N/O film was pyrogenic oxidation at 85$0^{\circ}C$ for 30 minutes. The leakage current was reduced from 400pA to 7.5pA when SiO$_{2}$ film with thickness of 2nm was formed on the top of $Si_{3]N_{4}$ film by the pyrogenic oxidation method.

• 한국재료학회지
• /
• 제12권1호
• /
• pp.48-53
• /
• 2002

$Al_2O_3-SiC$ and $Al_2O_3-SiC$-TiC composite powders were prepared by SHS process using $SiO_2,\;TiO_2$, Al and C as raw materials. Aluminum powder was used as reducing agent of $SiO_2,\;TiO_2$ and activated charcoal was used as carbon source. In the preparations of $Al_2O_3-SiC$, the effect of the molar ratio in raw materials, compaction pressure, preheating temperature and atmosphere were investigated. The most important variable affecting the synthesis of $Al_2O_3-SiC$ was the molar ratio of carbon. Unreactants remained in the product among all conditions without compaction. The optimum condition in this reaction was $SiO_2$: Al: C=3: 5: 5.5, 80MPa compaction pressure under Preheating of $400^{\circ}C$ with Ar atmosphere. However there remains cabon in the optimum condition. The effect of $TiO_2$ as additive was investigated in the preparations of $Al_2O_3-SiC$. As a result of $TiO_2$ addition, $Al_2O_3-SiC$-TiC composite powder was prepared. The $Al_2O_3$ powder showed an angular type with 8 to $15{\mu}m$, and the particle size of SiC powder were 5~$10{\mu}m$ and TiC powder were 2 to $5{\mu}m$.

• 공업화학
• /
• 제7권4호
• /
• pp.691-697
• /
• 1996

천연고무 라텍스(NRL)와 각종 첨가제를 배합 숙성하여 NR 필름을 제조하였고, 클로로프렌고무 라텍스 (CRL)를 일정한 비율로 블렌드하여 NR/CR 필름을 제조하였다. 이들 필름의 전가류 시간에 따른 팽윤도와 기계적 성질의 변화를 측정한 결과, 팽윤도 80~85%, 전가류 시간 48~60hrs등에서 가장 우수하였고, CRL의 블렌드 비율이 증가함에 따라 인장강도는 감소하고 신장율은 증가하는 경향을 나타내었다. 제조공정을 달리하여 제조한 시편의 기계적특성을 비교한 결과, 1회 디핑법을 사용한 NR/CR 필름의 인장강도, 인열강도는 2회 디핑한 NR-d-CR 필름보다 더 우수하였다. 이들 시편의 표면을 SEM으로 관찰한 결과, CRL의 블렌드 비율이 증가할수록 필름 표면의 벌크한 집합체가 증가되는 것으로 보아 상분리가 일어났음을 관찰할 수 있었다.

• E2M - 전기 전자와 첨단 소재
• /
• 제10권7호
• /
• pp.674-681
• /
• 1997

Ternary compound ceramics, (1-y-x) BaTiO$_3$-y SrTiO$_3$-x MgTiO$_3$(0.00 x 0.20), were fabricated by the conventional ceramic process. The structural and dielectric properties of specimens were investigated while varying the composition and sintering temperature(1,200~1,45$0^{\circ}C$) in order to obtain the optimum condition of capacitor. As is well known, Curie temperature(T$_{c}$) of high dielectric-based ceramic(BaTiO$_3$) was shifted and temperature of capacitance was decreased in according to increase of solid solution with (Sr, Mg)TiO$_3$. As a result, a suitable condition of compound rate for capacitor was obtained such as the BSM-11(0.8BaTiO$_3$-0.1SrTiO$_3$-0.1MgTiO$_3$), and sintering temperature was sintered at 1,25$0^{\circ}C$ for two hours. In this case, dielectric constant<1,300, dielectric loss(tan$\delta$)<0.03, and the variation rate of capacitance had less than 3% in the range -10~7$0^{\circ}C$.>.

• 한국전기전자재료학회논문지
• /
• 제19권2호
• /
• pp.139-144
• /
• 2006

A fabrication condition of the cathode electrode was optimized in a lithium secondary battery. The $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ powders were used as a cathode material. The $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$/Li cells were prepared with a certain formulation and their cycleability and rate-capability were evaluated. Optimum electrode composition simulated from the evaluated value was 86.3: 5.6: 8.1 in mass $\%$ of active material: binder: conducting material. Discharge capacity decreased markedly as the press ratio exceeded $30\%$ during preparation of the electrode. Discharge performance at a high current rate deteriorated abruptly as the electrode thickness was over $120{\mu}m$.

• 한국재료학회지
• /
• 제12권3호
• /
• pp.169-175
• /
• 2002

Semiconductive nano $(Ba_{1-x}Sb_x)TiO_3$ powders were synthesized by the hydrothermal process and Sb was simultaneously doped in the hydrothermal condition. $(Ba_{1-x}Sb_x)TiO_3$ powders obtained from optimum condition(at 20$0^{\circ}C$ for 3hr) exhibited spherical shape, high purity and nano size. The PTCR characteristics was observed when 0.1 and 0.2 mole% Sb were added and sintered at over 130$0^{\circ}C$ for 1 hour, respectively. And The ceramics exhibit the PTCR characteristics with a resistively jump $ratio($\rho$_{max}/$\rho$_{min})$ of about $10^4$. Also we found that PTCR characteristics were dependent on the microstructure.

• Food Science and Biotechnology
• /
• 제18권5호
• /
• pp.1230-1236
• /
• 2009

Optimum conditions for the freeze-thaw stability (FTS) of mung bean starch (MBS) paste as a main ingredient in omija-eui were investigated. For the optimization of the paste preparation condition, the FTS of MBS prepared by boiling in a shaking water bath (BMSW) or by pressure-cooking in an autoclave (PCMA) were analyzed using a response surface methodology (RSM). In addition, the effects of various additives such as gums, sugars, and emulsifier were evaluated on the FTS of MBS paste prepared under optimal conditions. The predicted maximal FTS of MBS paste prepared by the PCMA method (73%) was higher than that of the paste prepared by the BMSW method (36%). In case of additives, gellan gum and sodium alginate effectively prevented the syneresis of MBS paste in the BMSW method and in the PCMA method, respectively. The use of a fructose fatty acid ester as an emulsifier decreased syneresis in a dose-dependent, while the addition of sugars accelerated syneresis. Consequently, MBS paste for omija-eui preparation may be efficiently prepared by adding sodium alginate and fructose fatty acid ester under the optimal conditions of 4.3% MBS content, $121^{\circ}C$ heating temperature, and $89^{\circ}C$ cooling temperature by pressure-cooking in an autoclave.

• 한국작물학회지
• /
• 제51권1호
• /
• pp.89-94
• /
• 2006

Traditionally fatty acid composition used to be analysed by a GC and the sample preparation process includes lipid extraction from sample and subsequent methyl esters preparation, which are time-consuming and cumbersome. As an alternative, simultaneous extraction/methylation methods are being developed for rapid and simplified sample preparation. To optimize one-step extraction/methylation method for analysis of fatty acid composition in brown rice, various reaction factors such as sample to reaction solution ratio, reaction time and temperature, shaking intensity were changed and resultant fatty acid composition data were evaluated in comparison with previous reports. The ratio of sample weight to reaction solution volume was the most critical factor in that higher sample to reaction solution ratio caused overestimation of palmitic acid and linoleic acid composition, resulting in underestimation of oleic acid. Lower reaction temperature also induced overestimation of linoleic acid and underestimation of oleic acid. Reaction duration and the intensity of shaking prior to and during the reaction, however, caused no significant changes in analysis results. In conclusion, the optimum condition was mixing 5 grains (about 0.2 g) of brown rice with $680{\mu}L$ of extraction/methylation mixture and $400{\mu}L$ of heptane, followed by reaction at $80^{\circ}C$ for 2 hours.

• 한국생활과학회지
• /
• 제23권2호
• /
• pp.357-366
• /
• 2014

In this study, we manufactured mung bean Dasik (pattern pressed candy) after selecting the optimum roasting conditions through physiochemical analysis and sensory evaluation. Then anti-oxidative abilities of roasted mung bean were measured in order to develop beauty food (Dasik) using roasted mung bean. In the content of vitexin and isovitexin of roasted mung bean, about 10 times the vitexin in the seed(60.85 mg/g) is found in the skin of raw mung bean, and about 9 times the isovitexin in the seed(71.42 mg/g) is also found in the peel. As a result of analyzing the seed and peel of mung bean after roasting it for 10, 20 and 30 minutes respectively, the optimum roasting condition is thought to be $110^{\circ}C$ for 30 minutes as the contents of vitexin and isovitexin showed the highest values of 104.94 mg/g and 122.02 mg/g respectively when the mung bean was roasted at $110^{\circ}C$ for 30 minutes. In the anti-oxidative activity evaluation of the optimum mung bean Dasik, the total content of phenol was shown to be 0.15 mg/mL, and the total content of flavonoid was shown to be 0.026 mg/mL. The DPPH radical scavenging ability showed a high vitality of 58.19%, and the ABTS radical scavenging ability was shown to be 13.26%.

• 한국식품과학회지
• /
• 제24권1호
• /
• pp.74-81
• /
• 1992

오미자를 이용하여 전통음료를 개발하기 위하여 최적 추출조건 및 적정배합비를 RSM program을 이용하여 조사하였다. 최적 추출조건 산출은 추출온도, 추출시간, 추출용매 농도의 3변수와 3수준의 fractional factorial design에 의하여 조사한 결과 추출온도 $80{\sim}85^{\circ}C$, 추출 시간 3시간, 추출용매는 물을 사용하는 것이 수율, 색, 비취발성 유기산의 양에서 가장 적절하였으며 적정배합비는 추출물, 설탕, 구연산 첨가량의 3변수와 3수준의 fractional factorial design에 의하여 조사한 결과 추출물 4%, 설탕 9.6%, 구연산 0.06%를 첨가하는 것이 음료의 향과 overall acceptance에서 가장 양호한 결과를 나타내었다.