• 한국산업보건학회지
• /
• 제8권1호
• /
• pp.1-23
• /
• 1998

Work-related Low Back Pain(LBP) is one of tile most important Issues in the field of industrial safety and health. Particularly, manual lifting is known as a major cause of work-related LBP and impairment. Total number of 163 manual lifting tasks in motor assembly processes were investigated. The 1981 and the 1994 equations developed by National Institute for Occupational Safety and Health(NIOSH) were applied to evaluate potential hazards of lifting-related LBP. Comparisons between the 19R I and 1994 NIOSH criteria were made. The relationships between the NIOSH criteria and lifting-related LBP were also analyzed. The results of this study are as follows: 1. The values of Action Limit(AL) by the NIOSH 1981 lifting equation. Recommended Weight Limit(RWL) by the 1994 equation and the weight of the load handled at each manual lifting task were shown log-normal distributions. 2. LI'(the weight of tile load/AL) and LI(the weight of the load/RWL) were calculated estimate the physical stress imposed by each individual lifting task. As a result. 76.7% of the total LI' value exceeded 1 and 12.9% exceeded 3, and 84.7% of the total LI values exceeded 1 and 20.9% exceeded 3. 3. Bus 2 Department showed the highest rate of LI'>1 and LI>1 and Bus 1 Department showed the highest rate of LI'>3 and LI>3 4. In general, the RWLs by the 1994 equation were found lower than the ALs by the 1981 equation. It is assumed to he resulted from the fact that the 1994 equation includes methods evaluating asymmetrical lifting tasks and lifts of objects with less then optimal hand-container couplings, and also covers a larger range of work durations and lifting frequencies than the 1981 equation. 5. Significant correlations were found between LI' and incidence of LBP (R=0.734, p<0.05). LI and incidence of LBP(R=0.671. p<0.10) and load-weights and incidence of LBP(R=0.797, p<0.05). 6. Control measures are required to achieve the value of LI less than 1 for some tasks having high LI values. Engineering control is highly recommended for some tasks having the value of LI above 3.

• 한국결정성장학회지
• /
• 제6권3호
• /
• pp.327-340
• /
• 1996

고주파로의 이용한 Czocharalski 법으로 congruent$(R_{m}=R_{c}=0.945)$, stoichiometric$(R_{m}=1,\;R_{c}=0.957)$, Li-rich$(R_{m}=1.202,\;R_{c}=0.989)$, congruent한 조성에 $K_{2}O$를 6 wt% 첨가한 $LiNbO_{3}$ 등의 순수한 단결정들과 congruent한 조성에 Mg와 Mn을 불순물로 첨가한 $LiNbO_{3}:Mn(0.1\;mole%),\;LiNbO_{3}:Mg(4.5,\;6.0,\;10.0\;mole%),\;LiNbO_{3}:(Mg(4.5,\;6.0,\;10.0\;mole%)+Mn(0.1\;mole%))$ 단결정들을 결정의 c.축 방향으로 성장시켰다. 실온데서 UV 스펙트럼과 IR 스펙트럼을 측정한 결과 UV 흡수단과 $OH^{-}$ 흡수 스펙트럼은 [Li]/[Nb] 비에 따라 변화한다. 또 첨가한 Mg, Mn 불순물들의 영향을 받는데 UV 흡수단의 위치와 $OH^{-}$ 흡수 스펙트럼의 위치, 모양이 Mg의 첨가량에 크게 의존하며 이는 Mg의 첨가량에 따라 이 이온의 결정내 위치가 달라지기 때문이다. 순수한 단별정들에 대한 $OH^{-}$ 흡수 스펙트럼을 Gaussian 선모습 함수를 써서 3, 5 개의 성분 스펙트럼으로 분해한다. 이 결과를 설명하기 위한 $LiNbO_{3}$ 단결정내의 배내, 배외 결함 구조에 대한 논의로 부터 Li 빈자리 모델이 결함 구조를 설명하는데 적합하다는 결론을 내렸고 이들 불순물 이온의 결정내의 위치도 정한다. 또한 결함 구조에 대한 본 연구의 결론을 이용하여 최근의 다른 연구자들의 실험 결과도 설명한다.

• 분석과학
• /
• 제13권6호
• /
• pp.759-765
• /
• 2000

전해제련법을 이용하여 $LiF-BeF_2-ZrF_4$ (67-27-6 mol%) 용융염에서 Zr 금속 분리실험을 수행하였다. $LiF-BeF_2$ (72-28 mol%) 용융염과 $LiF-BeF_2-ZrF_4$ (67-27-6 mol%) 용융염의 분해 전압은 각각 -1.55, -1.35 volt로 측정되었고, Zr 분리실험 결과 인가전압 범위는 -1.4 -1.5 volt 사이가 적당하였다. 인가전류가 증가할수록 전착량은 증가하나 전류효율은 감소하였다. 그리고 반응온도가 증가할수록 $ZrF_4$의 기화로 인하여 전착량과 전류효율이 감소하였다.

• 한국전기전자재료학회논문지
• /
• 제23권9호
• /
• pp.696-700
• /
• 2010

We fabricated red and blue organic light emitting display (OLEDs) which had the two kinds of multi-structure of ITO/HIL/HTL/EML/ETL/LiF/Al and ITO/HIL/HTL/EML/ETL/LiF/Al/LiF. In the case of red OLED that had LiF/Al/LiF structure compared to LiF/Al structure, the current density increased from 4.3 mA/$cm^2$ to 7.3 mA/$cm^2$, and the brightness increased from 488 cd/$m^2$ to 1,023 cd/$m^2$ at 7.0 V, and as a result the current efficiency was improved from 11.28 cd/A to 13.95 cd/A. Also in the case of blue OLED that had LiF on Al cathode layer, the current density increased from 1.2 mA/$cm^2$ to 1.8 mA/$cm^2$, and the brightness increased from 45 cd/$m^2$ to 85 cd/$m^2$ at 7.0 V, and as a result the current efficiency was improved from 3.69 cd/A to 4.82 cd/A. Through these experimental results it could be suggested that the LiF layer formed on Al prevents the oxidation of Al surface, and the electrode resistance become low with increase of supplied electrons, therefore the brightness and the efficiency are improved from the influence to the well-balanced bonding of electron and hole at emitting layer.

• The Korean Journal of Physiology
• /
• 제18권1호
• /
• pp.1-8
• /
• 1984

In order to determine the extent of the placental transfer of Lithium ion, pregnant rabbits at $27{\sim}29$ days of gestation, which has hemochorial placenta similar to the human placenta, received 2 mM/Kg of $Li^+$ in the form of LiCl intravenously. Maternal arterial blood, placental sinus blood, fetal blood, amniotic fluid and maternal urine were drawn two hours after the single dose of LiCl. Concentrations of $Li^+$, $Na^+$, $K^+$ and osmolarity were measured in plasma of collected bloods, amniotic fluid and urine. Followings are the results obtained. 1) Evident level of $Li^+$ was detected in fetal blood, although fetal plasma concentration of $Li^+$ found to be almost one third of maternal plasma. 2) Plasma concentration of $Li^+$ in placental sinus blood was higher than that in fetal plasma but lower than that in maternal plasma. It means that downward concentration gradient of $Li^+$ from mother to fetus was still remarkable two hours after the injection. 3) Significant level of $Li^+$ was also detected in amniotic fluid. It seemed likely that $Li^+$, at least in part, excreted by the fetal urinary tract. 4) There were no differences in $Na^+$ and osmolar concentration between fetal and maternal blood. 5) From above results, it was concluded that $Li^+$ may transfer across the placenta but limited passage capacity through placental barrier for $Li^+$ is significant, beacause net transfer assumed to be going on even at two hours, at which time maternal equlibrium has been reached.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 하계학술대회 논문집
• /
• pp.455-458
• /
• 2001

Spinel $LiMn_{2-y}$$M_{y}$ $O_4$powder was prepared solid-state method by calcining the mixture of LiOH - $H_2O$, Mn $O_2$, ZnO and MgO at 80$0^{\circ}C$ for 36h. To investigate the effect of substitution with Mg, Zn cation, charge-discharge experiments and initial impedance spectroscopy performed. The structure of $LiMn_{2-y}$$M_{y}$ $O_4$crystallites was analyzed from powder X-ray diffraction data as a cubic spinel, space group Fd3m. all cathode material showed spinel phase based on cubic phase in X-ray diffraction. Ununiform which calculated by (111) face and (222) face was constant in spite of the change of y value, except PUf\ulcorner LiM $n_2$ $O_4$. The discharge capacities of the cathode for the cation subbstitUtes $LiMn_{2-y}$$M_{y}$ $O_4$/Li cell at the 1st cycle and at the 40th cycle were about 120~124 and 108~112mAh/g except LiM $n_{1.9}$Z $n_{0.1}$ $O_4$/Li cell, respectively. This cell capacity is retained by 93% after 40th cycle. AC impedance of $LiMn_{2-y}$$M_{y}$ $O_4$/Li cells revealed the similar resistance of about 65~110$\Omega$ before cycling. before cycling.g.g.

• 한국세라믹학회지
• /
• 제53권6호
• /
• pp.712-718
• /
• 2016

In this study, we investigate the effect of the$Li_3BO_3$ additive on the densification and ionic conductivity of garnet-type $Li_7La_3Zr_2O_{12}$ solid electrolytes for all-solid-state lithium batteries. We analyze their densification behavior with the addition of $Li_3BO_3$ in the range of 2-10 wt.% by dilatometer measurements and isothermal sintering. Dilatometry analysis reveals that the sintering of $Li_7La_3Zr_2O_{12}-Li_3BO_3$ composites is characterized by two stages, resulting in two peaks, which show a significant dependence on the $Li_3BO_3$ additive content, in the shrinkage rate curves. Sintered density and total ion conductivity of the system increases with increasing $Li_3BO_3$ content. After sintering at $1100^{\circ}C$ for 8 h, the $Li_7La_3Zr_2O_{12}-8$ wt.% $Li_3BO_3$ composite shows a total ionic conductivity of $1.61{\times}10^{-5}Scm^{-1}$, while that of the pure $Li_7La_3Zr_2O_{12}$ is only $5.98{\times}10^{-6}Scm^{-1}$.

• 한국재료학회지
• /
• 제25권1호
• /
• pp.32-36
• /
• 2015

Hot rolling of Mg-6Zn-0.6Zr-0.4Ag-0.2Ca-(0, 8 wt%)Li powder was conducted at the temperature of $300^{\circ}C$ by putting the powder into the Cu pipe. The microstructure and mechanical properties of the samples were observed. Mg-6Zn-0.6Zr-0.4Ag-0.2Ca without Li element was consisted of ${\alpha}$ phase and precipitates. The microstructure of the 8 wt%Li containing alloy consisted of two phases (${\alpha}$-Mg phase and ${\beta}$-Li phase). In addition, $Mg_2Zn_3Li$ was formed in 8%Li added Mg-6Zn-0.6Zr-0.4Ag-0.2Ca alloy. By addition of the Li element, the non-basal planes were expanded to the rolling direction, which was different from the based Mg alloy without Li. The tensile strength was gradually decreased from 357.1 MPa to 264 MPa with increasing Li addition from 0% to 8%Li. However, the elongation of the alloys was remarkably increased from 10 % to 21% by addition of the Li element to 8%. It is clearly considered that the non-basal texture and ${\beta}$ phase contribute to the increase of elongation and formability.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
• /
• pp.147-147
• /
• 2015

The multilayer structure of the organic light emitting diode has merits of improving interfacial characteristics and helping carriers inject into emission layer and transport easier. There are many reports to control hole injection from anode electrode by using transition metal oxide as an anode buffer layer, such as V2O5, MoO3, NiO, and Fe3O4. In this study, we apply thin films of LiF which is usually inserted as a thin buffer layer between electron transport layer(ETL) and cathode, as an anode buffer layer to reduce the hole injection barrier height from ITO. The thickness of LiF as an anode buffer layer is tested from 0 nm to 1.0 nm. As shown in the figure 1 and 2, the luminous efficiency versus current density is improved by LiF anode buffer layer, and the threshold voltage is reduced when LiF buffer layer is increased up to 0.6 nm then the device does not work when LiF thickness is close to 1.0 nm As a result, we can confirm that the thin layer of LiF, about 0.6 nm, as an anode buffer reduces the hole injection barrier height from ITO, and this results the improved luminous efficiency. This study shows that LiF can be used as an anode buffer layer for improved hole injection as well as cathode buffer layer.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.363-364
• /
• 2007

Phospho-olivine $LiFePO_4$ cathode materials were prepared by hydrothermal reaction at different temperatures. The structural performance of $LiFePO_4$ powders were characterized by X-ray diffraction (XRD). $LiFePO_4$/Li batteries were characterized electrochemically by charge/discharge experiments. The XRD results demonstrate that $LiFePO_4$ powder has an orthorhombic olivine-type structure with a space group of Pnmb. Among the synthesized cathode materials, $LiFePO_4$synthesized at $170^{\circ}C$ and subsequently annealed at $500^{\circ}C$ shows the best electrochemical properties. It shows initial discharge capacity of $167\;mAh\;g^{-1}$ (98% of the theoretical capacity) close to the theoretical capacity of $LiFePO_4$ ($170\;mAh\;g^{-1}$) at 0.1 C rate, which is ascribed to the enhanced degree of crystallinity, better phase purity, more spherical and more finely dispersed nanoparticles, crystallization and activation of small amount impurity.