• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
• /
• pp.968-970
• /
• 1999

The trend of increasing of portable electric devices and demand for global environmental conservation have demands the development of high energy density rechargeable batteries. Lithium polymer battery has excellent theoretical energy density and energy conversion efficiency. Lithium polymer battery, included solid polymer electrolyte(SPE), can be viewed as a system suitable for wide applications from thin film batteries for microelectronics to electric vehicle batteries. The purpose of this paper is to research and development of flyash anode for lithium polymer battery. We investigated AC impedance response and charge/discharge characteristics of flyash/SPE/Li cells. The radius of semicircle associated with the interfacial resistance of flyash/SPE/Li cell increased very slowly during discharge process from 3.11V to 0.478V. And then the cell resistance was decreased at discharge process from 10% SOC to 0% SOC. Also, The radius of semicircle associated with the interfacial resistance of flyash/SPE/Li cell decreasing very slowly during charge process. And then the cell resistance was increased after 20th discharge precess. The discharge capacity based on flyash of 1st and 20th cycles was 276mAh/g and 143mAh/g.

• Journal of Electrochemical Science and Technology
• /
• 제7권4호
• /
• pp.269-276
• /
• 2016

Carbon-supported ordered Pt-Ti alloy nanoparticles were prepared as a durable and efficient oxygen reduction reaction (ORR) electrocatalyst for polymer electrolyte membrane fuel cells (PEMFCs) via wet chemical reduction of Pt and Ti precursors with heat treatment at $800^{\circ}C$. X-ray diffraction analysis confirmed that the prepared electrocatalysts with Ti precursor molar compositions of 40% (PtTi40) and 25% (PtTi25) had ordered $Pt_3Ti$ and $Pt_8Ti$ structures, respectively. Comparison of the ORR polarization before and after 1500 electrochemical cycles between 0.6 and 1.1 V showed little change in the ORR polarization curve of the electrocatalysts, demonstrating the high stability of the PtTi40 and PtTi25 alloys. Under the same conditions, commercial carbon-supported Pt nanoparticle electrocatalysts exhibited a negative potential shift (10 mV) in the ORR polarization curve after electrochemical cycling, indicating degradation of the ORR activity.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2019년도 추계학술대회
• /
• pp.70-72
• /
• 2019

For the safe and reliable operation of Lithium-ion batteries in Electric Vehicles (EVs) or Energy Storage Systems (ESSs), it is essential to have accurate information of the battery such as State of Charge (SOC). Many kinds of different techniques to estimate the SOC of the batteries have been developed so far such as the Kalman Filter. However, when it is applied to the multiple number of batteries it is difficult to maintain the accuracy of the estimation over all cells due to the difference in parameter value of each cell. Moreover the difference in the parameter of each cell may become larger as the operation time accumulates due to aging. In this paper a novel Deep Neural Network (DNN) based SOC estimation method for multi cell application is proposed. In the proposed method DNN is implemented to learn non-linear relationship of the voltage and current of the lithium-ion battery at different SOCs and different temperatures. In the training the voltage and current data of the Lithium battery at charge and discharge cycles obtained at different temperatures are used. After the comprehensive training with the data obtained with a cell resulting estimation algorithm is applied to the other cells. The experimental results show that the Mean Absolute Error (MAE) of the estimation is 0.56% at 25℃, and 3.16% at 60℃ with the proposed SOC estimation algorithm.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.361-362
• /
• 2007

Phospho-olivine $LiFePO_4$ cathode materials were prepared by hydrothermal reaction. Carbon black was added to enhance the electrical conductivity of $LiFePO_4$. The structural and morphological performance of $LiFePO_4$ and $LiFePO_4$-C powders were characterized by X-ray diffraction (XRD) and FE-SEM. $LiFePO_4/SPE/Li$ and $LiFePO_4$-C/SPE/Li cells were characterized electrochemically by charge/discharge experiments. The results showed that the discharge capacity of $LiFePO_4$-C/SPE/Li cell was 103 mAh/g at the first cycle. The discharge capacity of $LiFePO_4$-C/SPE/Li cell with 5 wt% carbon black was the largest among $LiFePO_4$-C/SPE/Li cells, 126 mAh/g at the first cycle and 123 mAh/g after 30 cycles, respectively. It was demonstrated that cycling performance of $LiFePO_4$-C/SPE/Li cell with 5 wt% carbon black was better than that of $LiFePO_4$/SPE/Li cell.

• Bulletin of the Korean Chemical Society
• /
• 제20권5호
• /
• pp.508-516
• /
• 1999

Polycrystalline powder of LixNi0.85Co0.15O2 was synthesized by pyrolyzing a powder precursor obtained by the PVA-precursor method. Coin cells of lithium-ion rechargeable battery were assembled, whose the cathodes were fabricated from the crystalline powders of LixNi0.85Co0.15O2 synthesized by the method. The effect of synthetic variation on the property of the cell was tested by carrying out 100 consecutive cycles of charge-dis-charge on the cells. The property of the cell was largely influenced by the pyrolysis conditions applied for the synthesis of the LixNi0.85Co0.15O2. Depending on whether the pyrolysis was carried out in standing air or in the flow of dry air, the discharge capacity and cycle-reversibility of the cell varied in large extent. When the powder precursor was pyrolyzed in standing air, a minor phase of lithium carbonate was remained in the LixNi0.85Co0.15O2. The carbon containing powder precursor had to be pyrolyzed in the flow of dry air to eliminate the minor phase. In the flow of dry air, the lithium carbonate in the precursor was eliminated over 500-700。C without any prominent heat event. By controlling the flow of air over the precursor during its pyrolysis, particle size could also be altered. The effect of flowing dry air, during first step pyrolysis or during second step heat treatment, on the property of the cell was discussed.

• 전력전자학회논문지
• /
• 제26권1호
• /
• pp.1-8
• /
• 2021

For the safe and reliable operation of lithium-ion batteries in electric vehicles or energy storage systems, having accurate information of the battery, such as the state of charge (SOC), is essential. Many different techniques of battery SOC estimation have been developed, such as the Kalman filter. However, when this filter is applied to multiple batteries, it has difficulty maintaining the accuracy of the estimation over all cells owing to the difference in parameter values of each cell. The difference in the parameter of each cell may increase as the operation time accumulates due to aging. In this paper, a novel deep neural network (DNN)-based SOC estimation method for multi-cell application is proposed. In the proposed method, DNN is implemented to determine the nonlinear relationships of the voltage and current at different SOCs and temperatures. In the training, the voltage and current data obtained at different temperatures during charge/discharge cycles are used. After the comprehensive training with the data obtained from the cycle test with a cell, the resulting algorithm is applied to estimate the SOC of other cells. Experimental results show that the mean absolute error of the estimation is 1.213% at 25℃ with the proposed DNN-based SOC estimation method.

• Clinical and Experimental Reproductive Medicine
• /
• 제32권1호
• /
• pp.47-54
• /
• 2005

Objective: Evaluation of embryos using early cleavage to 2-cell stage has been proposed, but a critical time-point for selecting embryos is unclear. The aim of the present study is to provide a guideline including critical time-point in the selection of early cleaving embryo for the reduction of multiple pregnancies as well as the increase of pregnancy rate in human IVF. Methods: This prospective study was performed in 116 cycles from 85 patients who underwent conventional IVF or ICSI at the infertility clinic of Good Moonhwa Hospital from January 2002 to December 2003. Early cleavage (EC) of embryos to 2-cell stage was assessed at 25 h and 27 h postinsemination/microinjection. Embryos that had early cleaved at each time point were designated as EC-1 and EC-2, respectively, while others were designated as non-early cleavage (NEC). Results: At least one early cleavage embryo was observed in 54 (46.6%) for the EC-1 and 84 (72.4%) for the EC-2 of the 116 cycles assessed. Clinical pregnancy rates (PR) were significantly higher in the EC-1 group (66.7%) compared to the EC-2 group (53.6%) or the NEC group (31.2%) (p<0.05). Significant improvement of the pregnancy rate was found when at least two or more embryos were early cleaved at 25 h postinsemination or when the proportion of early cleavage embryo at 25 h postinsemination was higher than 20% (p<0.05). Conclusion: The critical time-point for the selection of early cleavage embryos with high implantation potential is more effective in 25 h postinsemination/microinjection compared to 27 h. The proportion as well as number of early cleavage embryos is also an important factor for the prediction of pregnancy outcome and the chance of multiple pregnancies. These results demonstrated that the evaluation of early cleavage embryos to 2-cell stage is an easy, simple, and objective method for the selection of good quality embryos suitable for embryo transfer.

• 대한한방종양학회지
• /
• 제5권1호
• /
• pp.47-60
• /
• 1999

Traditional oriental medicines have been used for treatment of various kinds of human cancers for long times and some of them proven to be effective clinically. However, the pharmacological actions and mechanisms related to cancer treatment are generally unknown. In an effort to clarify the action mechanisms of several oriental medicines used for cancer treatments, we planned this experimental procedures. We selected Cordyceps sinensis (冬蟲下草), Punellae Herba (夏枯草), Rehmanniae Radix (熟地黃), Paeoniae Radix (白芍藥), Oldenlandiae Herba (白花蛇舌草), Partulaceae Herba (馬齒? ), Scdopendra subspinipes mutilans (蜈蚣), Mylabris Phalerara (班蟄), Phellinus igniarius(桑黃), Ganodermae Lignum(靈芝) for evaluation, which have been used for patients of gastric cancers. The twenty grams of medicines were boiled in 100ml of water for 1 hour and filtered with $0.2\;{\mu}m$ pore-sized filter unit to remove insoluble particles. Initially we evaluated the effects oriental medicines on growth inhibition in stomach cancer cells. The gastric cancer cell line, AGS, was cultured in RPMI 1640 supplemented with l0% heat-inactivated fetal bovine serum and treated with $10{\mu}l$ oriental medicines per 1ml of medium up to 48 hours. The specimens were subjected to MTT assay for evaluation of growth inhibition. We found mat Mylabris phalerata (班蟄) markedly suppressed the growth of cancer cells as shown in results. Next, we checked the effects of oriental medicines on cancer on cell cycles and apptosis. Mylabrls phalerata (班蟄) inhibited cell cycle progression of cancer cells a compared with control cells and cells treated with other medicines. In addition, Mylabri phalerata (班蟄) induced apoptosis in 30-40% of stomch cancer cells within 24 hours. Other oriental medicines used for this experiments did not show apoptosis-inducing effects on cancer cells. Finally, we determined the expression levels of genes associated with cell cycle and apoptosis. The expressions of Bcl-2 and bcl-XL were downregulated by the treatment of Mylabris phalerata (班蟄). However, the expression levels of genes related to cell cycles were not altered significantly. In conclusion, we found that Mylabris phalerata (班蟄) has in vivo gowth-inhibiting and apptosis-inducing effects on stomach cancer cells. However, we think that at least animal experiments are necessay for evduations.

• Journal of Chest Surgery
• /
• 제33권8호
• /
• pp.662-668
• /
• 2000

Background: Many recent results of clinical trials show that pre-operative concurrent chemoradiotherapy and surgical resection could increase the survival of N2 positive stage IIIA non-small cell lung cancer. This study was performed to assess the feasibility, toxicity, and affect rates of concurrent chemoradiotherapy and surgical resection in N2 positive stage IIIA non-small cell lung cancer. Material and Method: Thirty-one patients who underwent preoperative concurrent chemoradiotherapy for N2 positive stage IIIA non-small-cell lung cancer from May 1997 to April 1999 were entered into the study. Mean age was 61 yrs(43∼70 yrs), There were 24 men and 7 women. The confirmation of N2 disease were achieved through mediastinoscopic biopsy(24) and CT scans(7). Induction was achieved by two cycles of cisplatin and etoposide(EP) plus concurrent chest radiotherapy to 45 Gy. Resections were done at 3 weeks after the complection of preoperative concurrent chemoradiotherapy. Resections were performed in 23 patients, excluding 5 refusals and 3 distant metastasis. Result: All patients were compled the thoracic radiotherapy except one who had distant metastasis. Twenty three patients were completed the planned 2 cycles of EP chemotherapy, and 8 patients were received only 1 cycle for severe side effects(6), refusal(1), and distant metastasis(1). There was one postoperative mortality, and the cause of death was ARDS. Three patients who had neutropenic fever and one patient who had radiation pneumonitis were required admission and treatment. Esophagitis was the most common acute side effect, but relatively well-tolerated in most patients. The complection rate of concurrent chemoradiotherapy was 74%, resection rate was 71%, pathologic complete remission rate was 13.6%, and pathologic down-staging rate was 68%. Conclusion: Morbidity related to each treatment was acceptable and many of the patients have benefited down staging of its disease. Further prospective, preferably randomized, clinical trials of larger scale may be warranted to confirm the actual benefit of preoperative concurrent chemoradiotherapy and surgical resection in N2-positive stage IIIA non-small cell lung cancer.

• 한국수소및신에너지학회논문집
• /
• 제20권4호
• /
• pp.309-316
• /
• 2009

The effect of gas diffusion layers (GDLs) on the freeze/thaw condition durability in polymer electrolyte fuel cells (PEFCs) were investigated. For this purpose, three kinds of GDLs, such as, felt, paper and cloth types with different basic properties have been first prepared, then the changes in the properties and performance of cells was observed during the freeze/thaw cycles ranging from -30 to $70^{\circ}C$. The performance evaluations were conducted by using the single cells consisting of different GDLs. The performance degradation and the cell resistance increase could be directly correlated. The physical destruction of electrode was shown by SEM analysis. The mechanically supporting ability on the interface between the cell components can help enhancing the durability of PEFCs in the freeze/thaw condition.