• 한국재료학회지
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• 제3권3호
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• pp.207-214
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• 1993

$Li_2O-Al_2O_3-SiO_3$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.

• 대한화학회지
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• 제30권3호
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• pp.327-332
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• 1986

유도결합 플라스마 공간내의 전자밀도를 측정하였다. 전자밀도의 측정시 유도결합 플라스마의 작동조건은, (1) 냉각기체만 사용할 때, (2) 냉각기체와 운반기체만을 사용할 때, (3) 보통의 작동조건은, 즉 에아로졸을 포함한 운반기체를 사용할 때, (4) 약 88%의 에아로졸을 제거시켰을 때, 그리고 (5) 과량의 리튬을 주입시켰을 때로서 분류하였다. 보통의 작동조건에서 플라스마의 낮은 부분에서는 전자밀도가 상당히 감소하여 플라스마내의 가장 전자밀도가 큰 곳보다 약 80배 감소하였다. 이온화 방해영향을 일으키는 알칼리금속을 과량으로 넣었을 때 전자밀도의 변화는 관찰되지 않았고 유도코일의 power를 증가시키면 전자밀도도 증가하였다.

• 한국세라믹학회지
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• 제39권6호
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• pp.523-527
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• 2002

LiMn$_2$O$_4$ compounds were synthesized by calcining a mixture of LiOH and MnO$_2$(CMD) at 47$0^{\circ}C$ for 10 h and then calcining again at $650^{\circ}C$ to 90$0^{\circ}C$ fur 48 h in air with intermediate grinding. All the synthesized samples exhibited XRD patterns for the cubic spinel phase with a space group Fd3m. The lattice parameter increased gradually as the sintering temperature rose. The electrochemical cells were charged and discharged fur 20 cycles at a current density 300$\mu$A/$\textrm{cm}^2$ between 3.5 V and 4.3 V. The voltage vs. discharge capacity curves for all the samples showed two plateaus. The LiMn$_2$O$_4$ sample calcined at 90$0^{\circ}C$ had the largest first discharge capacity. This sample exhibited the best crystallinity, had relatively large lattice parameter and had relatively large particles with rectatively homogeneous size. All the samples showed good cycling performances. Among all the samples, the LiMn$_2$O$_4$ calcined at 85$0^{\circ}C$ had relatively large first discharge capacity and very good cycling performance. The addition of excess LiOH and the mixing in ethanol considered to help the formation of the more LiMn$_2$O$_4$ phase per unit weight sample and the more stable LiMn$_2$O$_4$phase. These led to the larger discharge capacities and the better cycling performances. The cyclic voltammograms fur the second cycle of the LiMn$_2$O$_4$ samples showed the oxidation and reduction peaks around 4.05 V and 4.18 V and around 4.08 V and 3.94 V, respectively. The larger first discharge capacity of the sample calcined at the higher temperature is related to the larger lattice parameter.

• 한국결정성장학회지
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• 제7권2호
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• pp.301-308
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• 1997

공진 주파수 온도 계수($\tau_1$)가 큰 음의 값을 가지는 ($Li_{1/2}Nd_{1/2}$)$TiO_3$(이하 LNT로 약함)계에 과잉의 $TiO_2$ 첨가량을 변화시키면서 제조하였고, 이에 의하여 생성되는 제 2상의 $TiO_2$가 LNT계에 미치는 미세구조, 상변화, 고주파 유전특성의 변화를 X-ray, SEM을 통해서 분석하였다. LNT계에 $TiO_2$를 5 mol%가지 첨가시에는 LNT의 결정립 경계에 액상의 $TiO_2$가 생성되어 밀도의 증진을 가지고 왔으나 전체적인 LNT구조의 불균일을 초래하여 고주파 유전특성저하를 가지고 왔다. 그러나 10 mol% 이상 첨가시에는 $TiO_2$ 상이 형성되어 LNT의 공진주파수의 온도계수의 값을 증진시킬 수 있었다.

• 대한화학회지
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• 제22권1호
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• pp.37-44
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• 1978

$BH_3$-THF 용액에 염화리튬을 가한 새로운 환원계의 환원특성에 대한 연구가 대표적인 작용기를 가진 유기화합물을 가지고 표준조건($0^{\circ}$, THF)에서 이루어졌다. 조사 연구된 화합물중 벤조페논, 4가지 에스테르 및 시클로헥센은 $BH_3$ 환원과 별 차이를 보이지 않았으나, 2-헵탄온, 아세토페논, 염화벤조일, 프탈산무수물, 그리고 3가지 에폭시화물은 소량의 염화리튬에 의해 빠른 속도로 환원이 완결 되었다. 특히 에폭시화시클로헥센의 환원에 있어서는 소량의 염화리튬 존재하에서는 정량적으로 시클로헥산올을 생성하였으나 염화리튬의 양이 증가하면 2-클로로시클로헥산올이 시클로헥산올과 함께 생성됨을 알았다. 또한, 에폭시화시클로헥센과의 반응에 있어서 질산리튬은 염화리튬과는 달리 별로 효과가 없었다. 따라서 보란-염화리튬용액에 클로로수소화붕소리튬의 생성가능성을 논의하였다.

• Journal of Electrochemical Science and Technology
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• 제15권1호
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• pp.168-177
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• 2024

Ni-rich cathode is one of the promising candidates for high-energy lithium-ion battery applications. Due to its specific capacity, easy industrialization, and good circulation ability, Ni-rich cathode materials have been widely used for lithium-ion batteries. However, due to the limitation of the co-precipitation method, including sewage pollution, and the instability of the long production cycles, developing a new efficient and environmentally friendly synthetic approach is critical. In this study, the Ni_0.91Co_0.06Mn_0.03CO₃ precursor powder was successfully synthesized by an efficient spray-drying method using carbonate compounds as a raw material. This Ni_0.91Co_0.06Mn_0.03CO₃ precursor was calcined by mixing with LiOH·H₂O (5 wt% excess) at 480℃ for 5 hours and then sintered at two different temperatures (780℃/800℃) for 15 hours under an oxygen atmosphere to complete the cathode active material preparation, which is a key component of lithium-ion batteries. As a result, LiNi_0.91Co_0.06Mn_0.03O₂ cathode active material powders were obtained successfully via a simple sintering process on the Ni_0.91Co_0.06Mn_0.03CO₃ precursor powder. Furthermore, the obtained LiNi_0.91Co_0.06Mn_0.03O₂ cathode active material powders were characterized. Overall, the material sintered at 780℃ shows superior electrochemical performance by delivering a discharge capacity of 190.76 mAh/g at 1^st cycle (0.1 C) and excellent capacity retention of 66.80% even after 50 cycles.

• 한국재료학회지
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• 제19권2호
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• pp.95-101
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• 2009

Glass ceramics were made from coal bottom ash by adding CaO and $Li_2O$ as glass modifiers and $TiO_2$ as a nucleating agent in a process of melting and quenching followed by a thermal treatment. The surface of the glass ceramics has 1.6 times more $Li_2O$ compared to the inner matrix. When $TiO_2$ was not added or when only 2 wt% was added, the surface parts of the glass ceramics were crystalline with a thickness close to $130{\mu}m$. In addition, the matrixes showed only the glass phase and not the crystalline phase. However, doping of $TiO_2$ from 4 wt% to 10 wt% began to create small crystalline phases in the matrix with an increase in the quantity of the crystalline. The matrix microstructure of glass ceramics containing $TiO_2$ in excess of 8 wt% was a mixture of dark-gray crystalline and white crystalline parts. These two parts had no considerable difference in terms of composition. It was thought that the crystallization mechanism affects the crystal growth, direction and shape and rather than the existence of two types of crystals.

• 대한전자공학회논문지SD
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• 제39권1호
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• pp.58-66
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• 2002

Tapered 방향성 가중 결합 음향파 도파로를 이용하여 음향광학형 파장가변 광 필터를 LiNbO₃와 Ti 이중 확산 공정 기술을 이용하여 제작하였다. 1551.1㎚ 파장의 TE, TM 입사 편광모드와 173.58㎒ 35㎽ RF구동 신호에 대해서 각각 -14.29㏈, -14.99㏈ 부 모드 억압과 61%, 86% 변환효율이 측정되었다. 파장변화율과 통과 대역폭은 8.6㎚/㎒ 1.8㎚로 측정되었으며, 스위칭 속도는 2.82㎲로 측정되었다. 2.5㎚ 채널 간격에 대해서 약 -l4㏈누화 레벨이 측정되었으며, 부 모드와 채널 간격이 누화에 매우 큰 영향을 미치고있음을 확인하였다.

• 동의생리병리학회지
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• 제19권3호
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• pp.573-579
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• 2005

The followings are the conclusions drawn from the clinical cases of apoplexy; The main cause of apoplexy is the deficiency of both Jung and Ki. dam typed persons are stricken with paralyses because of the insufficiency of the kidney water. On the other hand, bangkwang typed persons' apoplexy comes from the deficiency of Ki and dump-phlegm. The prevention of apoplexy is very important so that porpe medical care should be taken at the appearance of premonitory symptoms like vertigo, dim sight tinnitus, stiff neck, numbness and others. It appears very reasonable both clinically and pathologically that Li dongyuen classified the apoplexy in to three groups : the first group is apoplexy involving meridians ; the second. involving Bu ; the third, involving Jang. The accurate diagnosis of apoplexy regulates com prehension consideration of four factors configuration color, pulse and symptoms and distinction from the similar diseases. Apoplexy is the up wand floating of Yaug in deficiency due to the deficiency of genuine Yim. In its early stages it should be treated by eliminating the excess in the upper pant. In the lower pant becomes the fundamental treatment.

• 한국전기전자재료학회논문지
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• 제24권10호
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• pp.803-806
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• 2011

1 mol% $Li_2O$ excess $0.9(Na_{0.52}K_{0.48})NbO_3-0.1LiTaO_3$ lead-free piezoelectric multilayer ceramic actuators were investigated to determine their aging properties. To reduce the thermal aging behavior, we applied a rectified unipolar electric field of 5 kV/mm to the specimen to accelerate the electric aging behavior. By employing a rectified unipolar electric field for the piezoelectric actuators, we could remove undesirable heating from the relaxation current in the motion of the ferroelectric domain. To accelerate the aging test, the applied electric fields had a frequency of 900 Hz. To have enough time for charging and discharging, we employed an accurate time constant to design the equivalent circuit model for the aging tester. To extract exact aging behavior, we measured the pseudo-piezoelectric coefficient before and after the aging process. We also measured the electro-mechanical coupling coefficient, the frequency-dependent dielectric permittivity, and the impedance to compare with fresh and aged specimen.