• 공업화학
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• 제7권6호
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• pp.1105-1114
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• 1996

${\alpha}-PbO_2/IrO_2-TiO_2/Ti$지지체상에 sodium lauryl sulfate 및 $TiO_2$분말을 첨가한 질산납 전해액에서 전착한 ${\beta}-PbO_2$층의 특성 및 성능을 XRD, SEM, cyclic voltammograms, 매크로전해를 이용하여 검토하였다. XRD분석결과 sodium lauryl sulfate 및 $TiO_2$분말의 존재하에 ${\alpha}-PbO_2/IrO_2-TiO_2/Ti$ 지지체 위에 전착한 ${\beta}-PbO_2$층은 순수한 ${\beta}-PbO_2$층과 마찬가지로 정방정계구조를 나타냈다. SEM결과 sodium lauryl sulfate는 전착층의 결정입자크기를 작게 하는 경향을 보여준다. sodium lauryl sulfate 및 $TiO_2$분말의 존재하에 전착한 ${\beta}-PbO_2$전극은 KOH 및 $HClO_4$지지전해질에서 양극산화에 대한 산소과전압과 내구성을 크게 향상시켰다. 티타늄마드래스에 전착시킨 ${\beta}-PbO_2$전극을 이용하여 과염소산용액으로부터 오존 발생에 대한 전극성능과 내구성을 검토하였다. $HClO_4$지지전해질에 sodium lauryl sulfate와 $TiO_2$분말을 첨가하여 ${\alpha}-PbO_2/IrO_2-TiO_2/Ti$ 마드래스상에 전착한 ${\beta}-PbO_2$전극이 가장 높은 전류효율과 내구성을 가짐을 확인하였다.

• 한국환경과학회지
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• 제7권4호
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• pp.559-564
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• 1998

The effects of temperature, initial $Pb^{2+}$concentration and initial sludge concentration on the initial $Pb^{2+}$ removal rate and maximal $Pb^{2+}$removal amounts in activated sludge, respectively, were investigated. The removal of $Pb^{2+}$ in activated sludge was proved to be temperature-dependent process. The initial $Pb^{2+}$ removal rate increased from 187.5 to 261.4 mg $Pb^{2+}$/g sludge dry weight min, in response to the promoted temperature from 1$0^{\circ}C$ to 6$0^{\circ}C$, while the maximal $Pb^{2+}$removal amount (78.5 mg $Pb^{2+}$/g sludge dry weight) occurred at 30t . As the initial $Pb^{2+}$concentration increased from 36 to 228 mg $Pb^{2+}$/L at the constant temperature of 30C and initial sludge concentration of 1.5 g sludge dry weight/L, the time to reach an equilibrium state was almost independent of the initial $Pb^{2+}$concentration and the equilibrium $Pb^{2+}$/removal amount was increased Irom 41.9 to 73.6 mg $Pb^{2+}$/g sludge dry weight. On the contrary, the equilbrium $Pb^{2+}$ emoval amount was decreased from 87.7 to 65.3 mg $Pb^{2+}$/g sludge dry weight as the in- crease of initial sludge concentration from 0.22 to 1.76 g sludge dry weight/L.

• 한국세라믹학회지
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• 제32권12호
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• pp.1331-1336
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• 1995

The glass-ceramics for ferro-electric were made from compositions of 70PbO.16TiO2.8SiO2.4B2O3.2AlPO4 (wt%) and 67.5PbO.20TiO2.8.5SiO2.2B2O3.2AlPO4 (wt%). The crystallization kinetics for PbTiO3 crystalline phase formation from glass was studied using non-isothermal DSC techniques. The values of activation energy, ΔE using variables of heating rate and temperature were calculated at various reaction fractions obtained from peak area over DSC. The results indicated that activation energy was lowest at 60% reaction fractions and the activation energy of glass containing 20.0 wt% TiO2 is higher than that of glass containing 16.0 wt% TiO2. The crystallization mechanism was three dimensional growth (n=4).

• 한국결정학회지
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• 제13권3_4호
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• pp.172-176
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• 2002

Pb(Mg /sub 1/3/Nb/sub 2/3/)O₃-PbTiO₃ 계 완화형 강유전체에서 PbTiO₃ 첨가량 변화 및 온도 변화에 따른 상전이 거동을 초전특성 및 유전완화현상 고찰을 통해 고찰하였다. -40∼200℃의 상전이 온도범위에 걸쳐 초전 및 유전특성을 살펴보았으며 특히 Vogel-Fulcher 관계식에 의한 freezing temperature를 도출하였다. 이러한 모든 실험적 결과들로부터 기존에 제안되었던 Pb(Mg /sub 1/3/Nb/sub 2/3/)O₃-PbTiO₃ 고용체 시스템에 대한 상평형도를 다소 수정하여 제안하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 추계학술발표대회 개요집
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• pp.83-85
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• 2003

This paper is investigated the shear strength by using the micro shear-punch test method for Sn-37Pb alloy, binary and ternary alloys of environment-friendly Pb-free solder alloys which would be surely applicable to the electronic packages. As a result, in case of Max. shear strength, Sn-4Ag-0.5Cu has the highest value and Sn-37Pb has the lowest value on every condition of experiment temperature. Also, In case of Pb-free solder joint specimens, it was found that Pb-free solder alloys have higher value of shear strength than eutectic Sn-Pb solder alloy and Sn-4Ag-0.5Cu has the highest value.

• The Korean Journal of Ceramics
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• 제4권4호
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• pp.286-291
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• 1998

Dielectric properties of $Pb(Mg_{1/3}Nb_{2/3})O_{3}-PbTiO_{3}$, ceramics prepared by the columbite precursor method have been investigated as a function of the sintering temperature in the range of 1000∼$1250^{\circ}C$. The $Pb(Mg_{1/3}Nb_{2/3})O_{3}-PbTiO_{3}$ ceramics show typical relaxor ferroelectric behavior. As the sintering temperature increased, the dielectric constant increased and the phase transition temperature shifted to lower temperature. The TCK(temperature coefficient of dielectric constant) and VRK (variation rate of dielectric constant) increased with increasing sintering temperature. The $Pb(Mg_{1/3}Nb_{2/3})O_{3}-PbTiO_{3}$ compositions sintered at $1250^{\circ}C$ appear to be suitable for ferroelectric bolometer.

• 한국재료학회지
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• 제6권4호
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• pp.412-420
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• 1996

상업용 자동차 축전지 극판재료로 각형의 초정 Pb 재료에 적은 부피 분율의 Cu상을 가지는 Pb-Cu 합금을 응고시킬 때 각형의 초정 Cu 수지상이 석출되었다. 중요한 응고변수인 냉각속도와 Cu조성의양에 따른 각형의 Cu상의 형태변화를 조사하기 위하여 Pb-1wt%Cu, pb-3wt%Cu, Pb-5wt%Cu, Pb-9wt%Cu, Pb-12wt%Cu, 등의 5가지 합금이 선택되어 노냉, 공냉, 금형냉, 수냉의 4가지 냉각방법을 이용하여 실험하였다. 일반적으로 냉각속도와 Cu성분이 증가함에 따라 Cu상의 각형정도가 감소하였으며 결국 가장 빠른 냉각인 수냉각시에는 수지상 형태가 정출되지 않고 구형의 형태가 정출 되었다.

• 한국세라믹학회지
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• 제30권7호
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• pp.543-548
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• 1993

Stability and formation of Pb(Mg1/3Nb2/3)O3 (PMN) phase synthesized in Li2SO4-Na2SO4 molten salts have been investigated. And powder characteristics of PMN have been studied with a variation of processing parameters such as temperature, time, amount of the salts, and excess PbO. More ratio of Li2SO4 to Na2SO4 influences the percentage of perovskite phase due to the difference of the eutectic point of the salts, but does not influence the powder characteristics. The shape of PMN particles shows faceted morphology with bimodal distribution consisting with large and submicron parts. Particle size of PMN increased greatly with increasing soaking time or amount of salts rather than temperature. The addition of excess PbO resulted in round PMN crystallites without submicron particles. These results are discussed by XRD, SEM and thermal analyses.

• Journal of Nutrition and Health
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• 제23권7호
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• pp.492-503
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• 1990

This study was performed to investigate nutritional effect of various dietary fibers on lead absorption, and protein and lipid metabolisms in growing rats. Sixty male rats of Sprague-Dawley strain weighing 140$\pm$1.1g were blocked into 10 groups according to body weight and fed 10 kinds of diet different with fiber sources [non-fiber, cellulose, pectin, guar gum or carboxymethylcellulose(CMC)] and lead levels (0 or 1%) for 4 weeks. Results were summerized as follows : 1) Food intake, weight gain, FER and PER were remarkably decreased in lead(Pb)-added groups. Weight gain, FER and PER in Pb-added pectin group were significantly lower than those in Pb-added non-fiber group. 2) Liver and kidney weights, femur weight and length, hematocrit and hemoglobin content were decreased in Pb-added groups. Especially femur and liver weights in pectin groups were the lowest among groups. 3) Total protein content in serum was significantly decreased in Pb-added groups but was not different with dietary fiber sources. Total lipid content in serum was not different with dietary Pb levels and fiber sources, but cholesterol content in serum of guar gum group was significantly decreased by Pb addition. 4) Nitrogen, lipid and cholesteol contents in liver were significantly decreased in Pb-added groups, and lipid content in liver of pectin and CMC groups was lower than other groups. 5) Daily urinary and fecal excretions of nitrogen, kipid and cholesterol were decreased in Pb-added groups, and fecal nitrogen was significantly increased in Pb-added groups, and fecal nitrogen of cellulose and guar gum groups was significantly higher than other groups. Fecal excretions of lipid and cholesterol were increased by dietary fibers, and especially fecal lipid was remarkably increased in pectin and guar hum group. 6) Pb contents in liver and femur were decreased by dietary fibers. Especially Pb contents in liver, kidney and femur were significantly decreased in guar gum group. 7) Daily urinary and fecal excretions of Pb were significantly increased in cellulose and guar gum groups, and fecla excretion of Pb in guar gum group was twice of non-fiber group. Pb absorption ratio was significantly decreased in guar gum group. In conclusion, dietary fibers have effect on protein and lipid metabolisms, and decreased intestinal absorption of Pb by increasing fecal excretion. But the degree of effect was different with dietary fiber sources.

• Journal of Nutrition and Health
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• 제22권6호
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• pp.485-496
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• 1989

This study was performed to investigate nutritional effect of various dietary fibers on lead absorption and metabolism of protein and lipid in growing rats. Forty eight male rats of Sprague-Dawley strain weighing 75.7$\pm$0.7g were blocked into six groups according to body weight and fed six kinds of diet different with fiber source(non-fiber, cellulose, pectin) and lead level(0%, 1% ) for 4 weeks. Results are summerized as follows: 1) Food intake, weight gain, FER and PER were remarkably decreased in lead(Pb) added groups, and FER and PER in Pb-added pectin group were significantly lower than those in Pb-added non-fiber group. 2) Weight of liver, kidney and epididymal fat pad, bone weight and length, hematocrit, and hemoglobin content were decreased in Pb-added groups. 3) Total protein content in serum was tended to be decreased in Pb-added groups, but total lipid and cholesterol contents in serum were not different with dietary Pb level and fiber source. 4) Nitrogen, lipid and cholesterol content in liver were tended to be deceased in Pb-added groups, and especially those of the Pb-added pectin group were the lowest among groups. 5) Daily urinary and fecal excretions of nitrogen, lipid and cholesterol were decreased in Pb-added groups. Especially fecal excretions of nitrogen, lipid and cholesterol in Pb-free groups were significantly increased by dietary cellulose and pectin. 6) Pb content in blood was significantly increased in Pb-added pectin group. There was no significant decrease in Pb contents of liver, kidney and tibia, and increase in excretion of Pb by feeding dietary fibers. In conculsion, dietary fibers had no effect on the absorption of Pb, and dietary pectin seemed to increase Pb poisoning by decreasing bioavailibility of protein, lipid and other nutrients in the diet.