• Journal of Electrochemical Science and Technology
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• 제3권4호
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• pp.172-177
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• 2012

Mo-doped $LiFePO_4$ was synthesized via co-precipitation method using sucrose as the carbon source. Structure, surface morphology, and the electrochemical properties of the synthesized olivine compounds were investigated using Rietveld refinement of X-ray diffraction data (XRD), scanning electron microscopy (SEM), and electrochemical charge-ischarge tests. Spherical morphology with the particle size of ${\sim}8{\mu}m$ authenticated the enhanced tap density and volumetric energy density of the synthesized materials. Charge-discharge behavior of $LiFePO_4$ and Mo-doped $LiFePO_4$ cells demonstrated a specific capacity of 130 and 145 mAh $g^{-1}$, respectively. Mo-doped $LiFePO_4$ cells exhibited an excellent discharge capacity at 96 mAh $g^{-1}$ at 7 C-rate.

• 대한전자공학회논문지SD
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• 제44권11호
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• pp.109-118
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• 2007

SoC의 집적도와 동작 속도의 증가로 인하여 지연 고장 테스트의 중요성이 더욱 커지고 있다. 본 논문은 천이 지연 고장 테스트를 지원하는 개선된 IEEE 1500 래퍼 셀 구조와 IEEE 1149.1 TAP 제어기를 이용하기 위한 인터페이스 회로를 제시하고 이를 이용한 테스트 방법을 제안 한다. 제안 하는 셀 구조는 한 번의 테스트 명령어를 이용하여 상승 지연 고장 테스트와 하강 지연 고장 테스트를 연속적으로 수행 할 수 기능을 유지하면서 기존의 셀 구조에 비하여 적은 면적 오버헤드를 가지며 테스트 시간을 줄일 수 있다. 또한 다른 클럭으로 동작하는 코어에 대한 테스트를 동시에 수행 할 수 있다.

• Environmental Analysis Health and Toxicology
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• 제14권4호
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• pp.203-216
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• 1999

This paper describes a set of multi-pathway models for estimating health risk to lead. The models link concentrations of an environmental contaminant (lead) in air, water and food to human exposure through inhalation, ingestion, and dietary routes. Exposure is used as the foundation for predicting risk of health detriment within the population. The process of estimating exposure using often limited data and extrapolating to a large diverse population requires many assumption, inferences, and simplification. This paper is divided into four section. The first section provides lead contaminant levels on obtaining environmental concentration of air, tap water, and foods. The second section provides a discussion of exposure parameters and uncertainty associated predicting human health risk of contaminants. The third and fourth section illustrate lifetime average daily exposure (LADE) and excess cancer risk (ECR) based on exposure parameters. The relationship between concentration of lead in an environmental medium and human exposure is determined with pathway exposure factors (PEFs). The calculation of LADE and ECR is carried out using Monte-Carlo simulation with probability density function of exposure parameters. Examination of the result reveals that, for lead exposure, ingestion (food) is the dominant route of exposure rather than inhalation (air), and ingestion (tap eater).

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.913-924
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• 2011

A steady-state analysis has been conducted to predict the behavior of the slag layer in the entrained-flow slagging coal gasifier. The analysis takes into consideration the composition dependent slag properties such as density, viscosity, heat capacity, thermal conductivity, and temperature of critical viscosity. The amount of added flux to the design coal and the variation of syngas temperature inside the gasifier have been adopted as calculation parameters. The predicted results are the local thickness of the molten and the solid slag layers, and the slag viscosity and the velocity distribution across the molten slag layer along the gasifier wall near the slag tap.

• 한국분말재료학회지
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• 제21권5호
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• pp.331-337
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• 2014

The effects of particle size of Li-Si alloy and LiCl-KCl addition as a binder phase for raw material of anode were investigated on the formability of the thermal battery anode. The formability was evaluated with respect to filling density, tap density, compaction density, spring-back and compressive strength. With increasing particle size of Li-Si alloy powder, densities increased while spring-back and compressive strength decreased. Since the small spring-back is beneficial to avoiding breakage of pressed compacts, larger particles might be more suitable for anode forming. The increasing amount of LiCl-KCl binder phase contributed to reducing spring-back, improving the formability of anode powder too. The control of particle size also seems to be helpful to get double pressed pellets, which consisted of two layer of anode and electrolyte.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.259-259
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• 2007

층상구조의 전이금속 산화물($LiMO_2$, M=Co, Ni, Mn)은 리튬이차전지용 양극재료로 활발한 연구가 진행되고 있다. 차세대 리튬이차전지 시스템의 개발 및 고성능화를 위해서는 전지의 용량을 결정하는 핵심 부품인 양극재료의 고용량화 및 고안정화는 필수 불가결하다. 따라서 본 연구에서는 상업적으로 큰 장점이 있는 고상반응 공정을 이용하여 리튬이차전지용 양극소재를 제조하고, 소재의 전기화학적, 구조적인 특성을 평가하였으며, 다음과 같은 주제를 가지고 연구를 진행하였다. $LiCoO_2$ 양극재료는 리튬이온전지로 널리 사용되고 있다. 높은 에너지 밀도의 리튬이온전지를 얻기 위해서는 $LiCoO_2$ 양극재료가 고용량화 및 고밀도화를 가져야 한다. 여기서 $LiCoO_2$ 분말이 irregular particle morphology를 가지면 tap density가 $2.2-2.4gcm^{-3}$로 에너지 밀도가 낮으나, 구형 $LiCoO_2$의 정극재료는 tap density가 $2.6-2.8gcm^{-3}$로 상대적으로 energy density가 높아지는 효과가 있다. 구형 $LiCoO_2$ 양극재료를 합성하기 위해서는 chelating agent를 이용한 "controlled crystallization" 침전법을 사용하여 합성한 구형 코발트 수화물을 사용하고 있다. "controlled crystallization" 침전법에서 사용되는 chelating agent로는 주로 ammonia가 이용되고 있다. 본 연구에서는 chelating agent로 ethylene diamine을 사용하여 sodium hydroxides를 precipitation으로 침전 반응하여 구형 코발트 수화물을 합성하였다. 상기 방법으로 합성된 코발트 수화물과 리튬 수화물($LiOH{\cdot}H_2O$-고순도화학(高殉道化學))을 사용하여 고상법을 통하여 $LiCoO_2$를 합성하였다. 제조된 분말의 결정구조와 전기화학적 특성분석은 X-선 회절분석 및 리트벨트 구조정산, 그리고 충/방전 싸이클링을 수행하였으며, 분말의 미세구조 변화를 SEM을 이용하여 분석하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1550-1552
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• 1994

In order to investigate the effect of electrolyte solutions on the activities of bow-tie water trees in XLPE insulated power cable, we have tried to observe the characteristics on water treeing ( bow-tie type ) using several electrolyte solutions such as $CH_3COOH$, $MgCl_2$,HCl and NaCl solution and tap water. Bow-tie tree density in $CH_3COOH$ and $MgCl_2$ solution was higher than in any other solution, and the growth of tree was stimulated in NaCl and $CH_3COOH$ solution, and diffusion of bow-tie trees into insulation in $MgCl_2$, HCl and NaCl solutions was faster than in $CH_3COOH$ solution and water. Also, although the increase of applied voltage caused bow-tie tree density to be high, it didn't affect the growth of tree maximum length noticeably.

• Journal of Pharmaceutical Investigation
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• 제40권6호
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• pp.347-351
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• 2010

Isoflavones have received much attention because of their health-related and clinical benefits such as estrogenic and anti-oxidative activities as well as triggering of natural killer cell activity. However, there are few publications reporting the pharmacokinetic profiles together with physicochemical properties of main isoflavones. Therefore, the pharmacokinetic parameters of main aglycones, daidzein, glycitein and genistein after oral administration of soybean extracts were investigated and the physicochemical properties of soybean extracts were characterized. It was observed that angle of repose was $46^{\circ}$ and tap density, bulk density and porosity were 10.12, 4.3 and $0.86\;g/cm^3$ and the mean $AUC_{last}$ of daidzein, glycitein and genistein was $11.376\;{\mu}g{\cdot}h/mL$, $3.045\;{\mu}g{\cdot}h/mL$ and $0.825\;{\mu}g{\cdot}h/mL$, respectively. Cell viability was 60% at a concentration of 10 mg/mL. Taken together, it was suggested that isoflavones were contained in the soybean products and had an antioxidant activity and this study would be the basis to control the quality of soybean products and study of the bioequivalence between soybean products in future.

• 대한건축학회논문집:구조계
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• 제34권6호
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• pp.29-34
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• 2018

In this research, regarding the cement supplied to ready mixed concrete plant, the feasibility of rapid acquisition test for cement fineness using hydrometer which used for early strength evaluation of concrete was analyzed. Additionally, regarding the rapid test with hydrometer control factors were provided. As a result of analysis, quality control using hydrometer was possible with the regressive equation obtained in five minute between density of suspension and fineness of cement powder. As the control factors, dispersing admixture, replacing kerosene as a medium, and temperature of cement and water were evaluated. According to the control factor evaluation, the tap water was optimum as a medium and calibration of keeping the temperature of water to $20^{\circ}C$ or correction factor was needed for density results. Finally, it is considered that the suggested rapid quality evaluation method using hydrometer is cheaper and easier method than currently used Blaine test.

• 생명과학회지
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• 제14권6호
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• pp.891-894
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• 2004

배급수관망에 사용되는 아연도강관과 탄소강관이, 수돗물속에서 생장시키는 생물막의 세균농도와 미생물군집의 양상을 비교하기 위하여 Biolog GN plate를 이용한 CLPP를 수행하였다. 세균농도는 $10^4\;-\;10^6\;CFU/cm^2$이었고, 탄소강관과 아연도강관에 따른 생물막의 세균농도는 유의한 차이가 없었다. 평균적인 발색양상은 비슷하였지만 개별적인 CLPP 양상은 재질과 시기에 따라 다른 것으로 나타나, 미생물군집의 양상이 시간과 재질에 따라 다른 것을 알 수 있었다.