• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.125-128
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• 2007

In these recent years, low cost and stable battery electrode materials have been studied for HV/HEV application. Spinel cathode material $LiMn_2O_4$ is widely studied as a promising cathode material of lithium ion secondary batteries because of it is low cost, easily to be prepared and capable to be operated in high voltage range. In this study, $LiMn_2O_4$ was undergoing surface modification with spinel lithium titanium oxide by sol-gel method in order to enhance its capacity retention. Properties of both unmodified and surface-modified $LiMn_2O_4$ were characterized by XRD, SEM, particle size analyzer while their cycling performance was tested with charge and discharge tester.

• 한국수정란이식학회지
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• 제15권1호
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• pp.1-8
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• 2000

The ultrasound-guided oocytes cllection (ovum pick-up ; OPU) has become a substitution for superovlation in cattle. The objective of this study was to examine the effect of OPU frequency on the in vitro production of embryos in Hanwoo cattle. Six cycling Hanwoo cows were distributed into two groups for either once or twice weekly OPU sessions. Oocytes were collected by ultrasound-guided follicle aspiration(SA600) using a 6.5HMz transducer and attached with 18 gauge needle, with vacuum pressure of 40 mmHg. The cumulus-oocyte complexes (COCs) collected from each donor were matured in TCM 199 supplemented with 10% fetal bovine serum at 5% CO2 in air at 38.5$^{\circ}C$ for 22h and in vitro matured oocytes were co-incubated with sperm(separated by Percoll gradient) for 6h. The zygotes were co-cultured on cumulus cell monolayer in 10ul droplets in the same culture medium and conditions used for IVM for 7 days. On Day 7 of culture, development to blastocysts was examined. Although the number of oocytes collected was variable depending on individuals, overall embryo production in the twice per week OPU sessions was better that in the once per week sessions(6~21 vs 2~7 blastocysts produced, respectively). Two cows(E, A) were good oocyte donors and embryo production was superior in cow C ; however, cow F was a poor donor as compared to the others. In conclusion, these results suggest that for embryo production, twice weekly OPU sessions were better than once per week for producing embryos in vitro from Hanwoo cattle.

• Asian-Australasian Journal of Animal Sciences
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• 제16권12호
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• pp.1716-1721
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• 2003

Steroid hormones and their receptors play an important role in reproductive process. Estrogen is intimately involved with pregnancy and its function is mediated through the estrogen receptor which has been chosen as a candidate gene to study litter size in pigs. In this study, we report that two estrogen receptor variants, designated pER-1 and pER-2 were co-expressed in the uteri of normal cycling Lan-Yu pig (Sus vittatus; a small-ear miniature in Taiwan) with the pER-1 expression level appeared to be several times higher than that of pER-2. These receptor variants were isolated using reverse transcription-PCR from the pig uteri and their sequences were determined. The pER-1 and pER-2 sequences, which are homologous to those found in other mammalian estrogen receptors, encode putative proteins consisting of 574 and 486 amino acids, respectively. A deletion in exon I was identified in both sequences, with deletion lengths of 63 bp in pER-1 and 327 bp in pER-2. The deletion in pER-1 is internal to that in pER-2 and both deletions resulted in a truncation of the B domain, which confers the transactivating activity of estrogen receptor protein. This result describes the existence of estrogen receptor variants with a deletion in exon I and implies the possibility that physiological functioning of an estrogen receptor may not require the presence of an intact B domain.

• 한국수소및신에너지학회논문집
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• 제10권4호
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• pp.225-232
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• 1999

Ni-MH 2차 전지의 음극재료로 사용되는 수소저장합금중 이론 방전용량이 가장 높은 $Mg_2Ni$를 기계적 합금법으로 제조하여 각종 첨가물의 첨가에 따른 전기화학적 특성을 조사하였다. $Mg_2Ni$는 고에너지 볼밀인 SPEX 8000을 이용하여 두가지 방법으로 제조하였다. 하나는 Mg, Ni 분말에 첨가물인 $AB_5$, $AB_2$계 수소저장합금과 Ni, Co, Cu를 첨가하여 12시간 볼밀링한 경우이고, 다른 하나는 먼저 Mg, Ni 분말을 1시간동안 볼밀링한 후 $300{\sim}400^{\circ}C$에서 열처리하여 $Mg_2Ni$를 제조한 후 여기에 첨가물을 10wt% 첨가하여 12 시간동안 볼밀할 경우이다. 이 볼밀링한 복합분말을 상온에서 $754tons/cm^2$의 압력으로 냉간압착하여 디스크 모양의 전극을 제조하였다. 실험결과 볼밀링 후 열처리를 거친 합금분말의 경우가 그렇지 않은 경우에 비해 전극의 방전용량이 높았으며, Ni을 첨가한 경우는 방전용량을 증가시키고 Co를 첨가한 경우는 싸이클 특성이 향상되었다. 특히 $Mg_2Ni$에 Ni을 10wt%를 첨가하여 12시간 볼밀한 경우 $Mg_2Ni$의 최대 방전용량은 546mAh/g.alloy으로 이론용량의 약 55%에 달했다.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1257-1261
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• 2010

The electrochemical performances of anode composites comprising elemental silicon (Si), silicon monoxide (SiO), and graphite (C) were investigated. The composite devoid of elemental silicon (SiO:C = 1:1) and its carbon coated composite showed reduced capacity degradation with measured values of 606 and 584 mAh/g at the fiftieth cycle. The capacity retention nature when the composites were cycled followed the order of Si:SiO:C = 3:1:4 < Si:SiO:C = 2:2:4 < SiO:C = 1:1 < SiO:C = 1:1 (carbon coated). A comparison of the capacity retention properties for the composites in terms of the silicon content showed that a reduced silicon content increased the stability of the composite electrodes. Even though the carbon-coated composite delivered low capacity during cycling compared to the other composites, its low capacity degradation made the anode a better choice for lithium ion batteries.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3077-3083
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• 2010

The electrochemical detection of As(III) was investigated on a platinum-iron(III) nanoparticles modified multiwalled carbon nanotube on glassy carbon electrode(nanoPt-Fe(III)/MWCNT/GCE) in 0.1 M $H_2SO_4$. The nanoPt-Fe(III)/MWCNT/GCE was prepared via continuous potential cycling in the range from -0.8 to 0.7 V (vs. Ag/AgCl), in 0.1 M KCl solution containing 0.9 mM $K_2PtCl_6$ and 0.6 mM $FeCl_3$. The Pt nanoparticles and iron oxide were co-electrodeposited into the MWCNT-Nafion composite film on GCE. The resulting electrode was examined by cyclic voltammetry (CV), scanning electron microscopy (SEM), and anodic stripping voltammetry (ASV). For the detection of As(III), the nanoPt-Fe(III)/MWCNT/GCE showed low detection limit of 10 nM (0.75 ppb) and high sensitivity of $4.76\;{\mu}A{\mu}M^{-1}$, while the World Health Organization's guideline value of arsenic for drinking water is 10 ppb. It is worth to note that the electrode presents no interference from copper ion, which is the most serious interfering species in arsenic detection.

• Journal of Electrochemical Science and Technology
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• 제12권2호
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• pp.285-295
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• 2021

The inverse spinel Cobalt ferrite (CoFe₂O₄, CFO) is considered to be a promising alternative to commercial graphite anodes for lithium ion batteries (LIBs). However, the further development of CFO is limited by its unstable structure during battery cycling and low electrical conductivity. In an effort to address the challenge, we construct three-dimensional hierarchical flower-like CFO nanoclusters (CFO NCs)-decorated carbonized cotton carbon fiber (CFO NCs/CCF) composite. This structure is consisted of microfibers and nanoflower cluster composited of CFO nanoparticle, in which CCF can be used as a long-range conductive matrix, while flower-like CFO NCs can provide abundant active sites, large electrode/electrolyte interface, short lithium ion diffusion path, and alleviated structural stress. As anode materials in LIBs, the flower-like CFO NCs/CCF exhibits excellent electrochemical performance. After 100 cycles at a current density of 0.3 A g^-1, the CFO NCs/CCF delivers a discharge/charge capacity of 1008/990 mAh g^-1. Even at a high current density of 15 A g^-1, it still maintains a charge/discharge capacity of 362/361 mAh g^-1.

• Corrosion Science and Technology
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• 제22권6호
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• pp.408-418
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• 2023

In this study, we synthesized and characterized garnet-type Li_7-xAl_xLa₃Zr_2-(5/4)yNbyO₁₂ (LALZN) solid electrolytes for all-solid-state battery applications. Our novel approach focused on enhancing ionic conductivity, which is crucial for battery efficiency. A systematic examination found that co-doping with Al and Nb significantly improved this conductivity. Al³⁺ and Nb⁵⁺ ions were incorporated at Li⁺ and Zr⁴⁺ sites, respectively. This doping resulted in LALZN electrolytes with optimized properties, most notably enhanced ionic conductivity. An optimized mixture with 0.25 mol each of Al and Nb dopants achieved a peak conductivity of 1.32 × 10^-4 S cm^-1. We fabricated symmetric cells using these electrolytes and observed excellent charge-discharge profiles and remarkable cycling longevity, demonstrating the potential for long-term application in battery systems. The garnet-type LALZN solid electrolytes, with their high ionic conductivity and stability, show great potential for enhancing the performance of all-solid-state batteries. This study not only advances the understanding of effective doping strategies but also underscores the practical applicability of the LALZN system in modern energy storage solutions.

• 한국가축번식학회지
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• 제17권2호
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• pp.159-164
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• 1993

성숙한 gilt를 이용하여 estrous cycle과 pregnancyrlrks 동안 OCD효소의 tissue내 함량을 측정하는 것이 본 연구의 주 목적이었다. 하루 한 마리의 gilt를 estrous cycle day 3, 10, 17, 18, 19, 20 그리고 pregnancy day 11, 12, 13, 14, 18, 19, 20, 48, 50, 52에 도살하였다. 시상하부, 뇌하수체, 자궁, 난소 및 골겨근에서 조직을 제거하였으며, 이들 조직들을 완충액에 넣어 균질화 시켰으며 그 상청액은 단백질량과 ODC의 활력도를 측정하였는데 사용되었다. Radiolabled ormithine에서 발생하는 14CO2양은 0.124∼4mg범위내에서 단백질첨가량과 배양시간에 비례하였다. OCD는 특히 estrous cycle day 19일에 뇌하수체, 난소 그리고 자궁에서 활발한 활동을 보여주었다. 한편, 시상하부와 골격근에서 ODC는 그 어떤 활동도 보이지 않았다. 자궁조직은 다른 조직들에 비해 보다 활발한 ODC활동을 보여 주었다(P<0.05).

• 대한소아치과학회지
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• 제35권2호
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• pp.287-296
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• 2008

본 연구는 항우식 제품인 저농도의 불소 양치액(500 ppm NaF)과 Casein phosphopeptide-amorphous calcium phosphate(CPP-ACP)를 포함하는 치아 연고, 그리고 이 두 제품을 같이 사용했을 경우, 인공 우식 병소의 재광화 효과를 알아보고자 하였다. 제3대구치 협면에 인공우식을 유발하였고, 시편을 16개씩 4군으로 나누어, 28일 동안 매일 2 회 다음과 같은 항우식 제품을 시편에 처리하였고, pH 순환 시스템을 적용하였다. 1군: 대조군(무처치) 2군: Tooth $Mousse^{(R)}$ (GC Co. Japan) 3군: 치카치카$^{(R)}$ (삼일제약. 한국) 4군: 치카치카$^{(R)}$+Tooth Mousse$^{(R)}$ 무기질 소실량(${\Delta}Q$)의 장기적인 변화를 Quantitative light-induced fluorescence(QLF)를 이용하여 관찰하여 다음과 같은 결과를 얻었다. 1. ${\Delta}Q$는 1군에서는 28일동안 유의성 있는 차이를 보이지 않았고, 2군과 3군에서는 처치전에 비해 14일부터 유의성 있는 증가를 보였으며, 4군에서는 7일부터 유의성 있는 증가를 보였다. 2. ${\Delta}Q$는 1군 < 2군, 3군 < 4군 순이었다. 3. ${\Delta}Q$는 1군과 비교시 2군은 7일, 3군과 4군은 3일부터 유의성 있는 증가를 보였고, 2군은 3군과 전 기간 동안 유의차가 없었다. 4군은 2군과 3군에 비해 28일에 유의성 있는 증가를 보였다. 4. 모든 군에서 재광화 속도는 점차 감소하였다.