• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.1-5
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• 2021

The PEM(Proton Exchange Membrane)water electrolysis uses the same PEM electrolyte membrane as the PEM fuel cell and proceeds by the same reaction but the opposite direction. The PEM fuel cell has many methods of degradation analysis since many studies have been conducted on the degradation and durability of the membrane and catalyst. We examined whether PEM fuel cell durability evaluation method can be applied to PEM electrolytic durability evaluation. During the PEM electrolytic degradation process, LSV(Linear sweep voltammetry), CV(Cyclic voltammetry), Impedance, SEM(Scanning Electron Microscope) and FT-IR(Fourier Transform Infrared spectroscopy) were analyzed and compared under the same conditions as the PEM fuel cell. As the PEM fuel cell, hydrogen passing through the membrane was oxidized at the Pt/C electrode, and the hydrogen permeation current density was measured to analyze the degree of degradation of the PEM membrane. Electrode degradation could be analyzed by measuring the electrode active area (ECSA) by CV under hydrogen/nitrogen flowing conditions. While supplying hydrogen and air to the Pt/C electrode and the IrO2 electrode, the impedance of each electrode was measured to evaluate the durability of the electrode and membrane.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.60-64
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• 2010

Purpose: Until now the general study for breast cancer patient has been mammography, breast sonography for anatomic diagnostics and $^{18}F$-FDG whole body PET for functional one. But the PEM (Positron Emission Mammography) was developed to increase sensitivity, specificity and accuracy to improve the disadvantage of each study. Therefore this present study aims to describe availability of PEM for improving diagnosis of breast cancer. Materials and Methods: During 3 months from January in 2010, PEM was performed on 100 patients who had history of breast cancer. Using Naviscan's PEM Flex Solo II scanner, PEM images of breast were acquired. And then we evaluated sensitivity, specificity and accuracy of PEM data by comparing results of PEM images with postoperative pathologic finding. Results: On the 100 patients, it could reveal 89 true positive, 9 false positive, 7 false negative and 87 true negative. Thus the results of sensitivity, specificity and accuracy for PEM was evaluated 92.7%, 90.6% and 91.7%. Conclusion: The sensitivity, specificity and accuracy have been reported 83.7%, 68.5% and 77.1% in mammography, and that was 89.1%, 79.1% and 83.4% in breast sonography. However the results of PEM were more increased than others. Therefore the results of this study will be available that PEM used diagnosis with breast cancer, used preoperative operation plan and helps to discovery of a part recurrence.

• Membrane Journal
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• v.30 no.4
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• pp.213-227
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• 2020

As unrenewable energy resources have depleted over the years, the demand for renewable energy has increased promoting research for more effective methods to produce renewable energy. The field of fuel cell development, specifically microbial fuel cells (MFCs), has developed because of the dual performance potential of the technology. MFCs convert power by facilitating electrode-reducing organisms such as bacteria (microbes) as a catalyst to produce electrical energy. MFCs use domestic and industrial wastewater as fuel to initiate the process, purifying the wastewater as a result. Proton exchange membranes (PEM) play a crucial role in MFCs as a separator between the anodes and cathodes chambers allowing only protons to effectively pass through. Nafion is the commercially used PEM for MFCs, but there are many setbacks: such as cost, production time, and less effective proton conductivity properties. In this review there will be largely two parts. Firstly, several newly developed PEM are discussed as possible replacements of Nafion. Secondly, MFC based on PEM, blended PEM and composite PEM are summarized.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.2
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• pp.134-141
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• 2010

Small PEM (Proton Exchange Membrane) fuel cell systems do not require humidification and have great commercialization possibilities. However, methods for controlling small PEM fuel cell stacks have not been clearly established. In this paper, a control method for small PEM fuel cell systems using a dual closed loop with a static feedforward structure is defined and realized using a DSP (Digital Signal Processor). The fundamental elements that need to be controlled in fuel cell systems include the supply of air and hydrogen, water management inside the stack, and heat management of the stack. For small PEM fuel cell stacks operated without a separate humidifier, fans are essential for air supply, heat management, and water management of the stack. A purge valve discharges surplus water from the stack. The proposed method controls the fan using double control loops to quicken transient response of the fan thereby improving the supply rate of air. Feedback control to compensate for the voltage change in fuel cell stack improves the response characteristics in fuel cell to load variations. The feasibility of proposed method was proved by the experiments with a 60W small PEM fuel cell system and operation of a notebook computer using this system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.8
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• pp.566-573
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• 2019

In order to obtain high-quality images by motion compensation in the airborne synthetic aperture radar (SAR), accurate motion sensing in image acquisition section is necessary. Especially, reducing relative position error and discontinuity in motion sensing is important. To overcome the problem, we propose a pre-parametric error modeling (P-PEM) algorithm which is a real-time motion sensing algorithm for the airborne SAR in this paper. P-PEM is an extended version of parametric error modeling (PEM) method which is a motion sensing algorithm to mitigate the errors in the previous work. PEM estimates polynomial coefficients of INS error which can be assumed as a polynomial in the short term. Otherwise, P-PEM estimates polynomial coefficients in advance and uses at image acquisition section. Simulation results show that the P-PEM reduces relative position error and discontinuity effectively in real-time.

• BMB Reports
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• v.39 no.4
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• pp.371-376
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• 2006

Crustacean hyperglycemic hormone (CHH) plays a major role in controlling glucose level in the haemolymph and also triggers important events during molting and reproductive cycles. In Penaeus monodon, three types of CHH, namely Pem-CHH1, Pem-CHH2 and Pem-CHH3, have been previously characterized. In this study, mouse polyclonal antibody was raised against recombinant Pem-CHH1 that was expressed in Escherichia coli. The anti-Pem-CHH1 antibody recognized all three types of Pem-CHHs but did not cross-react with either related hormone, molt-inhibiting hormone of P. monodon, or unrelated human growth hormone. The hyperglycemic activity in the extract from the eyestalk neural tissues was significantly depleted after incubating with anti-Pem-CHH antibody. Direct injection of the antibody into shrimp caused about 30-50% reduction in the haemolymph glucose level. The result demonstrates the ability of anti-Pem-CHH1 antibody to deplete the activity of CHH in vivo, and thus provides a possibility of using anti-Pem-CHH1 antibody to inhibit the hormone activity as a strategy to modulate growth and reproduction in this species.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.662-669
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• 2006

PEM(Prestressed Earth Method) is a method to minimize lateral movements of the ground generated by progressive excavation and increases shear strength by applying prestresses to the end of earth bolt equipped with a P.C. panel after earth bolt is set up under the in-situ ground. In case of PEM, there are noticeable advantages. First of all, PEM maximizes the utility of the ground because PEM needs less volume of backfill and cutting than other general walls. Second, it's an environmental method possible to garden on the banquette. In this study, the behavioral characteristics of PEM are analyzed and compared with soil nailing system through the measured data of PEM and numerical method using SMAP-2D program and also an increased stability of PEM is evaluated by increasing prestress of earth bolts through the numerical analysis using Slide (ver. 4.0) program.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.11
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• pp.1377-1384
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• 2007

A previous study suggested that the phyto-extract mixture (PEM381) containing Camellia sinensis (leaf), Psidium guajava (leaf), and Rosa hybrida (flower) inhibited not only arachidonic acid cascade-related enzymes (5-lipoxygenase and cyclooxygenase) in vitro but also degranulation and histamine release from rat peritoneal mast cells. In this study, the same PEM381 was used to investigate its inhibitory effects on the syntheses of leukotrienes and prostaglandins as well as on serum concentration of histamine and eosinophils infiltration in type I allergic reaction-induced mice. The PEM381 could decrease concentrations of serum cysteinyl leukotrienes from mice activated by anti-DNP IgE and DNP-albumin. The concentration of serum histamine by oral administration of PEM381 (25, 50, and 100 mg/kg of body weight) in type I allergic reaction-induced mice was $395.93{\pm}190.37$ nM, $315.59{\pm}164.23$ nM, and $325.07{\pm}112.02$ nM, respectively, while that of positive control (promethazine hydrochloride 10 mg/kg of body weight) was $270.12{\pm}24.02$ nM. In addition, the PEM381 also showed inhibitory effect on the eosinophils infiltration in the nasal mucosa of mice which were sensitized with ovalbumin. However, the effect of PEM381 on the syntheses of prostaglandins seemed to be insignificant. Consequently, these results suggest that PEM381 may be useful for the prevention and treatment of type I allergy-related diseases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.5
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• pp.439-447
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• 2000

The PEM(Personal Environment Module) system is an individual air conditioning system developed in order to improve thermal comfort in office buildings. In this study, thermal characteristics of a PEM system have measured experimentally and compared with UFAC(Under Floor hir Conditioning) system in the EC(Environment Chamber) constructed in KIER. Results showed that the PEM system was better than UFAC system for thermal comfort and energy conservation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.2
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• pp.155-162
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• 2007

The purpose of this study is to investigate the anti type I allergic effects and mechanisms of the phyto extract mixture (PEM381) which contains Camellia sinensis (leaf), Psidium guajava (leaf), and Rosa hybrida (flower). PEM381 was tested for its inhibitory effects on arachidonic acid cascade related enzymes (5-lipoxygenase and cyclooxygenase), the mast cell mediated allergic reaction and passive cutaneous anaphylaxis. $IC_{50}$ value of PEM381 against 5-lipoxygenase was $14.11{\pm}0.51ppm$ while that of positive control (nordihy-droguaiaretic acid) was $0.54{\pm}0.08ppm$. PEM381 also exhibited considerable selective inhibition of cyclooxygenase-2. PEM381 could inhibit both degranulation and histamine release in a dose dependent manner from rat peritoneal mast cells activated by compound 48/80. In addition, oral administration of PEM381 showed an inhibitory effect on passive cutaneous anaphylaxis reaction activated by anti-dinitrophenyl IgE antibody in mice. These results suggest that PEM381 may be useful for the prevention and treatment of type Ⅰ allergy related diseases.