• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.84-84
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• 2009

$BaTiO_3$는 perovskite 구조를 가지는 대표적인 강유전체 재료로서 MLCC (Multi Layer Ceramic Capacitor), PTC thermistor등에 널리 사용되어지고 있다. 최근 고용량 MLCC의 상업화와 함께 나노크기를 갖는 tetragonal phase의 $BaTiO_3$ 입자를 합성하기 위한 다양한 제조방법이 제시되고 있다. 또한 유전특성과 온도특성 및 신뢰성을 향상시키기 위해 많은 첨가제들이 연구되어지고 있다. 따라서 본 연구에서는 희토류 원소인 $Y_2O_3$를 첨가하여 유전특성 및 온도특성을 향상시키고자 하였다. 본 실험에서는 150nm 크기를 갖는 pure $BaTiO_3$ 분말을 사용하고 $Y_2O_3$의 양은 0.02 ~ 0.1wt%로 변수를 주어 첨가하였으며, 최적의 소결 조건을 찾기 위하여 1200, 1230, $1250^{\circ}C$에서 소결을 진행하였다. 실험방법으로는 균일한 혼합을 위하여 Iso-alcohol을 이용하여 48시간 ball-mill 하였으며 오븐에서 건조 후 ${\Phi}15$로 성형하여 소결을 진행하였다. 실험결과로는 $Y_2O_3$ 첨가량이 0.02wt% 부터 상온부터 상전이 온도 부근의 유전율 기울기는 완만해 지는 것을 확인할 수 있었으며, 소결시편의 정방정비 (tetragonality)도 뚜렷하게 나타났다. $Y_2O_3$ 첨가랑이 0.1 wt% 일 때는 첨가량의 증가로 인해 강유전성이 상쇄됨을 나타냈다. 이는 $2450^{\circ}C$에 이르는 매우 높은 용융온도와 $2350^{\circ}C$까지 상전이가 는 $Y_2O_3$를 미량 첨가할 때, 고온에서 높은 화학적 안정성과 내열성을 가져 온도 안정성이 향상된 것으로 판단된다.

• Journal of Korea Foresty Energy
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• v.23 no.1
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• pp.26-37
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• 2004

This study was to investigate the rational propagation of the Vitex rotundifolia, which is distributed as a community naturally at coastal area in Korea. The germination rate of ordinary temperature stored fruits was the highest with 67%. In the matter of the number of seedlings per fruit, 1 seed germinated fruit was the most with 40.3 % and the mean was 1.4 seedlings per fruit. The best rooting rate of both greenwood and hardwood cutting was 96.7% in the case of cuttings soaked in IBA 2500ppm for 1 minute on the Compost+Sand bed-soils. Generally the root development of cuttings was higher in the high IBA concentration with soaking in a moment than in the low IBA concentration with soaking in long time, and bed-soils mixed with sands and composts. And in the rooting rate, greenwood cutting was better about 10% than hardwood cutting of Vitex rotundifolia.

• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.386-390
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• 2016

The surface of carbon nanotubes (CNTs) was modified by fluorination and applied to conductive materials to improve the energy efficiency of a capacitive desalination (CDI) electrode. CNTs were fluorinated at room temperature with a mixed gas of fluorine and nitrogen, and activated carbon based CDI electrodes were then prepared by adding 0-0.5 wt% of untreated CNTs or fluorinated CNTs with respect to the activated carbon. Fluorinated CNTs showed improved dispersibility in the electrode and also slurry as compared to untreated CNTs, which was confirmed by the zeta potential and scanning electron microscopy. Fluorinated CNTs added electrodes showed higher desalination efficiency but lower energy consumption than those of using untreated CNTs added electrodes. This was attributed to the decrease in the resistance of CDI electrodes due to the improved dispersibility of CNTs by fluorination.

• Clean Technology
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• v.21 no.2
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• pp.108-116
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• 2015

Hydrogen sulfide and ammonia are one of the common malodorous compounds that can be found in emissions from many sewages treatment plants and industrial plants. Therefore, removing these harmful gases from emissions is of significance in both life and industry because they can cause health problems to human and detrimental effects on the catalysts. In this work, pyrolytic carbon blacks from waste tires were used to develop adsorbent with good adsorption capacity for removal of hydrogen and ammonia. Pellet-type adsorbents were prepared by a mixture of carbon black, metal oxide and sodium hydroxide or hydrochloric acid, and their adsorption capacities were estimated by using breakthrough curve of a continuous fixed bed adsorption column at ambient condition. The adsorbent manufactured with a mixture of carbon black, iron oxide(III) and sodium hydroxide showed the maximum working capacity of hydrogen sulfide. For ammonia, maximum working capacity was obtained by the adsorbent manufactured with a mixture of carbon black, copper oxide(II) and hydrochloric acid.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.6
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• pp.283-287
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• 2002

We have studied Zr(Si)N film as a diffusion barrier between Cu metal and Si substrate for application of interconnection metal in ULSI circuits. Zr(Si)N film was deposited with reactive DC magnetron sputtering system using $Ar/N_2$mixed gas. The value of the resistivity was the lowest for the ZrN film using 29 : 1 of Ar : $N_2$reactant gas ratio at room temperature and decreased with increasing of Si substrate temperature. As the value of ZrN film resistivity was decreased, the direction of crystal growth was toward to (002) plane. The barrier property of ZrN film added with Si was improved. But Si was added too much in ZrN film, the barrier property was degraded. The adhesive property was improved with increasing of Si in ZrN. For the analysis of the film, XRD, Optical microscopy, Scretch tester, so on were used.

• Economic and Environmental Geology
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• v.37 no.4
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• pp.375-381
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• 2004

Pyrochlore was known as one of the most promising materials for the immobilization of radioactive actinide. This study includes the synthesis, phase relation and characteristics of pyrochlores (CaCeH$f_xTi_{2-x}O_7$=0.2, 0.6, 1.0, 1.4, 1.8, 2.0) in the system of Ca-Ce-Hf-Ti-O. The samples were prepared from high purity of starting materials under the pressure of 400kg/cm$^2$ at room temperature, and were sintered at 1200∼1$600^{\circ}C$ The synthesized samples were analyzed and identified with XRD. The optimal formation conditions of pyrochlores were at 1300∼150$0^{\circ}C$ under $O_2$ atmosphere with batch compositions. During synthesis, pyrochlore, perovskite and $A_{2}BO_{5}$ oxide were formed. The characteristics of this system is that parameter of pyrochlore was increased with the content of hafnium. This phenomenon was due to the difference of ionic size between hafnium and titanium in six coordinated site.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.2
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• pp.98-108
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• 2007

In order to use food wastes for the source of fermented feed for pigs, this study was aimed to produce better culture inoculum by the aeration and addition of pig' s blood meal as sub nutrient. For the preparation of inoculum as bacterial strain, Lactobacillus brevis isolated from pig intestine, and a yeast Saccharomyces cerevisiae from strawberries were used. Molasses and whey were used as main ingredients for the culture solution as well as yeast extract and other ingredients as sub nutrients. As the experimental result, aeration showed a positive effect to enhance viable cell count or retarding death phase. Although sub nutrient yeast extracts were replaced with pig's blood meal, fermentation characteristics were almost similar to that of yeast extract. When the inoculum was stored at room temperature, L. brevis and S. cerevisiae maintained the viable cell concentration of approximately 8 log cfu/mL for 1 week. 2 Days after the culture solution was mixed with food waste, the number of unwanted bacteria had rapidly increased, but E.coli was not detected for 5 days.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.93-93
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• 2012

섬유산업은 그 제조 스트림이 높은 오염 부하와 에너지 다소비를 특징으로 하여 환경규제에 따라 기존 시장의 위축 가능성이 상존하고 있다. 특히 섬유산업의 주요 스트림 중의 하나인 염색가공 공정은 섬유에서 불순물을 제거하고 심미한 색상과 사용 목적에 적합한 성능을 부여하는 단계로 섬유제조 공정에서 가장 높은 부가가치를 부여하는 단계이나 고온의 물과 다양한 화공약품을 많이 사용하고 그 처리온도가 비교적 높아($100^{\circ}C$ 이상) 대표적인 폐수 발생 공정이자 에너지 다소비 공정이다. 섬유의 염색 방법 중 반연속방법인 CPB(Cold Pad Batch)염색은 반응성 염료와 알칼리의 혼합액으로 구성된 염액에 원단을 패딩한 후 상온에서 수 시간 배칭하고 수세 및 후처리하여 염색하는 방법으로 작업공정관리, 설비관리가 간편하고 에너지소비량 절감, 높은 생산성의 장점이 있다. CPB염색법은 주로 직물에 적용되어 보편화 되었으며, 작업공정 중 장력의 영향을 많이 받는 니트 소재에 적용되는 사례는 드물다. 직물류의 CPB 염색가공법은 대구 경북을 중심으로 연구진행이 활발히 이루어지고 있어 국내 100대 정도의 CPB 관련 장비가 직물제품에 한정되어 가동되고 있는 반면, 니트 CPB 관련 염색 가공 업체는 1곳에 불과한 실정이나 니트류에 대한 지속적인 수요 증가를 고려하면 니트 소재에 대한 CPB염색 적용은 시의적절한 필수요소라고 판단된다. 니트 소재에 대한 CPB염색가공 적용 시 나타나는 문제점은 작업원단의 변부 말림현상 발생, 전폭 상태에서의 색상차이인 listing현상, 원단의 첫도입부분과 끝부분의 색상차이인 tailing현상이며, 반복되는 작업 시 염색재현성을 확보하는 것으로 나타난다. 본 연구에서는 CPB염색 시 CPB Head 장치의 Padding 방식 즉, trough와 Nip type에 따른 염색 시 알칼리와 염료 투입에 따른 염색 재현성(Build up, Ending, 알칼리 안정성)을 비교해 보았으며, 이에 따른 염색제품의 물성 및 견뢰도를 확인하여 보다 효율적인 방식을 선별하였다.

• Korean Journal of Food Science and Technology
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• v.23 no.6
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• pp.689-694
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• 1991

Jangsu, a Korean ancient non-alcoholic beverage made by lactic acid fermentation of cooked rice, was prepared and the microbial characteristics were investigated. The periodic removal of fermented product and the addition of newly made cooked rice and cold water as new substrate enhanced the growth of lactic acid forming bacteria but supressed the growth of proteolytic bacteria. The important microorganisms in jangsu were Lactobacillus, Lactococcus, Pediococccus and Leuconostoc species. Lactococcus thermophilus, Lactobacillus coryniformis and Leuconostoc mesenteroides were identified. The isolated strains were cultivated and used as starter culture of jangsu. Some useful strains were selected which were able to produce acceptable flavor and sufficient amount of acid lowering the pH to near 4.0.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.467-470
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• 2011

In this study, two different kind of impeller, commercial hand blender and manual type were used to investigate the most effective mixing method for simulant gel propellant. Ionized Water, Carbopol 941 and NaOH were used to produce the simulant gel for temperature of $25^{\circ}C$ and $50^{\circ}C$. The amount of bubbles produced during mixing of simulant gel at $50^{\circ}C$ were higher than that of simulant gel at $25^{\circ}C$. After 24 hours, bubbles of simulant gel made at $50^{\circ}C$ disappeared rapidly with respect to the bubbles of gel made at $25^{\circ}C$. Bubbles from blender did show notable amount even after 24 hours. Among mixing type, it was found that the pitched paddle impeller was the best candidate for the production of simulant gel.