• Journal of The Korean Society of Inherited Metabolic disease
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• v.13 no.2
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• pp.75-80
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• 2013

Specific genetic conditions may lead to sudden unexpected deaths in infancy, such as inborn errors of fatty acid oxidation and genetic disorders of cardiac ion channels. The disease may present dramatically with severe hypoketotic hypoglycemia, Reye syndrome or sudden death, typically with a peak of frequency around 3-6 month, whilst neonatal sudden death is quite rare. When undetected, approximately 20-25% of infants will die or suffer permanent neurologic impairment as a consequence of the first acute metabolic decompensation. Meanwhile, the advent of newborn screening for metabolic diseases has revealed populations of patients with disorders of fatty acid oxidation (FAO), the most frequent of which is medium chain acyl-CoA dehydrogenase (MCAD) deficiency. Without this screening, affected individuals would likely succumb to sudden infant death syndrome (SIDS). Here we describe an overview of sudden infant death syndrome and inherited metabolic disorder.

• Bulletin of the Korean Chemical Society
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• v.15 no.6
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• pp.453-455
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• 1994

Semiempirical MO calculations are applied to estimate the substituent effects on acylations of the nonfused N-vinyl-2-amino $\beta-lactams$ having frameworks analogous to 3-cephems. The stabilization energy for the reaction intermediate of the nucleophilic attack by the hydroxide ion is selected as the reactivity index and calculated by AM1 and PM3 methods for the model $\beta-lactams$ with substituents at the C1 and N-vinyl terminal positions. The reactivities are larger for -SH connected to the C1 and strong $\pi-acceptors$ at the N-vinyl terminal implying the large reactivity for known active cephalosporins. Quantum chemical calculation of stabilization energy could be useful in correlating antibiotic activities of many compounds obtained as derivatives of a lead compound.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.965-973
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• 2021

Since radiation therapy is irradiated with high-energy X-rays in a variety of at least 20 Gy to 80 Gy, a high dose is administered to the local area where the tumor is located, and various side effects of some normal tissues are expected. Currently, in clinical practice, lead, a representative material, is used as an effort to shield normal tissues, but lead is classified as a heavy metal harmful to the human body, and a large amount of skin contact can cause poisoning. Therefore, this study intends to manufacture a measurement sheet that can compensate for the limitations of lead using the materials Tungsten, Brass, and Copper of the 3D printer of the FDM (Fused Deposition Modeling) method and to investigate the penetration performance. Tungsten mixed filament transmission measurement sheet size was 70 × 70 mm and thickness 1, 2, 4 mm using a 3D printer, and a linear accelerator (TrueBeam STx, S/N: 1187) was measured by irradiating 100 MU at SSD 100 cm and 5 cm in water using a water phantom, an ion chamber (FC-65G), and an elcetrometer (PTW UNIDOSE), and the permeability was evaluated. As a result of increasing the measurement sheet of each material by 1 mm, in the case of Tungsten sheet at 3.8 to 3.9 cm in 6 MV, the thickness of the lead shielding body was thinner than 6.5 cm, and in case of Tungsten sheet at 4.5 to 4.6 cm in 15 MV. The sheet was thinner than the existing lead shielding body thickness of 7 cm, and equivalent performance was confirmed. Through this study, the transmittance measurement sheet produced using Tungsten alloy filaments confirmed the possibility of transmission shielding in the high energy region. It has been confirmed that the usability as a substitute is also excellent. It is thought that it can be provided as basic data for the production of shielding agents with 3D printing technology in the future.

• Journal of the Korean Chemical Society
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• v.37 no.2
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• pp.228-236
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• 1993

The effect of ferric ion on the reaction of CH_3$MgI with benzylbromide was investigated by determining the product ratio between cross-coupling product, ethylbenzene (A) and homocoupling product, bibenzyl (B) in the presence of ferric ion. When CH_3$MgI prepared with pure magnesium was used, the ratio of A to B was 22 to 78 and with reagent grade magnesium, the ratio became 33 to 67 indicating that metallic impurities in magnesium affect the reaction mechanism to lead less homocoupling product, B. The ratio changes became significant when ferric chloride was added in the reaction mixture in catalytic amounts and the ratio of A to B reached to 80 to 20 at maximum. The reaction in the presence of ferric ion seems to follow mainly an ionic mechanism which involves iron-benzyl bromide ${\pi}$-complex formation. The complex formation is expected to be able to enhance ionic attack of CH_3$MgI on benzyl carbon to give more A.

• Journal of Korea Water Resources Association
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• v.45 no.10
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• pp.1051-1067
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• 2012

Increased use of water curtain facilities to keep green house warm during winter cultivation has been known to cause excessive groundwater ion which might lead to decline of groundwater level, resulting in streamflow depletion. Therefore it is required to quantitatively assess the effects of groundwater ion on the streamflow depletion such as magnitude and extent. The objective of this study is to assess the change of stream-aquifer interaction according to groundwater ion near stream. To this end, a green house cultivation land in Sooha-ri, Sindun-myun, Icheon-si, Gyonggi-do was selected as a field experimental site, and monitoring wells were established near and within stream to observe the water level and temperature changes over a long period of time. From the observed water level and temperature data, it was found that the river reach of interest changed to a losing stream pattern during the winter cultivation season due to groundwater level decline around pumping wells near the stream. The continuous exchange rates between stream and aquifer were estimated by plugging the observed water level data series into the experimental relation between head difference and exchange rate, showing the streamflow depletion by 16% of the groundwater pumping rate in Feb, 2011.

• Journal of Bio-Environment Control
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• v.11 no.4
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• pp.188-192
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• 2002

High concentrations of HCO$_3$$^{[-10]}$ (bicarbonate ion) in hydroponic water lead to high pH and to change in solubility, and consequently inhibition of absorption of available iou. An adequate and practical method is needed to remove HCO$_3$$^{[-10]}$ in the water fur hydroponics. to compare the efficiency of HCO$_3$$^{[-10]}$ removal, the effect of injecting HNO$_3$, H$_3$PO$_4$ or H$_2$SO$_4$ was tested. Acid injection was effective to remove HCO$_3$$^{[-10]}$ Based on the assumption that an equivalent of HCO$_3$$^{[-10]}$ ion is neutralized by an equivalent of acid, KHCO$_3$ was dissolved in a double distilled water at 50, 100, 150, 200 or 250 mg.L$^{[-10]}$ concentration and either HNO$_3$, H$_3$PO$_4$ or H$_2$SO$_4$ was injected at a certain ratio, and the resulting pH change and HCO$_3$$^{[-10]}$ ion removal was measured. According to the results obtained, HCO$_3$$^{[-10]}$ in hydroponic water was titrated, and concentration of the residual HCO$_3$$^{[-10]}$ ion well correlated with the amount of acid injected.

• Membrane Journal
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• v.30 no.4
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• pp.228-241
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• 2020

Separators, which produces physical layer between a cathode and anode, are getting enormous attention as the quality of the separator determines the performance of lithium ion batteries (LIBs). Porous membranes based on polyethylene (PE) and polypropylene (PP) are generally utilized as the separator of LIBs because of their high electrochemical stability and suitable mechanical strength. However, low thermal resistance and wettability of PE and PP membranes limited the potential of LIBs. Operating at the temperature exceeding the melting point of membranes, the separators change their structures which lead to short circuit of LIBs. Low wettability of the separators corresponds to low ionic conductivity which increases the cell resistance. To overcome these weaknesses of PE and PP separators, different types of separator were prepared by co-electrospinning, applying coating layer, forming core shell around membrane, and papermaking method. The synthesized separator greatly enhanced the heat resistance and wettability of separator and mechanical properties like flexibility and tensile strength. In this review different type of polymer membrane used as separator in lithium ion battery are discussed.

• Journal of the Korean Chemical Society
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• v.55 no.1
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• pp.63-69
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• 2011

This work discusses the fabrication, development and potential response behaviors of $Ag^+$ ion-selective electrodes ($Ag^+$-ISE) based on N,N'-bis(2-hydroxybenzyl)-1,3-diaminopropane (L1) and N,N'-bis(2-hydroxybenzyl)-2,2-dimethyl-1,3-diaminopropane (L2) as carriers. The observations indicated that the resulting electrode based on L1 toward $Ag^+$ showed stable near-Nernst slope approaching 58.7 mV/dec and the optimum potential response characteristics in a linear range at least five orders of magnitude with a detection limit of $1.0{\times}10^{-6}M$. The proposed electrode displayed the preferential selectivity to $Ag^+$ against other tested cations. The excellent potential analytical characteristics could lead to the successful applications of silver assay in significant real samples, indicating that the proposed $Ag^+$-ISE showed a significant advancement of measurement capabilities. But for the electrode based on L2, the poor potential response characteristics were observed in total experiment process.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.572-580
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• 2019

Recently, it has been reported that benzyl alcohol (BzOH) as an additive in cosmetics, food, and medicine lead to toxicity and allergy problem. Then, to circumvent this hurdle, we carried out the synthesis of benzyl alcohol galactoside (BzO-gal). Previously, it was confirmed that BzO-gal was synthesized by transgalactosylation reaction using Escherichia coli (E. coli) ${\beta}$-galactosidase (${\beta}-gal$). Meanwhile, in this study, two peaks of BzO-gal as sodium adduct ion (m/z=293.1004) and protonated ion (m/z=271.1180) were detected in the reaction mixture by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS). In addition, the amount of ${\beta}-gal$ and BzOH concentration, temperature, pH, and lactose concentration, respectively, were optimized (${\beta}-gal$, 0.75 U/mL; BzOH, 185 mM; temperature, $40^{\circ}C$, pH, 7.5; lactose, 350 g/l). Under these optimal conditions, 185 mM BzOH was converted into about 131 mM BzO-gal, in which the conversion yield was about 72%. In the future, BzO-gal will be applicable as a substitute for BzOH as a less toxic preservative for the cosmetic, pharmaceutical, and food industries, and we are planning to investigate the characteristics of BzO-gal as a preservative.

• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.16-21
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• 1999

Purpose : The aim of this study is to conform the possibility of the liquid type EPID as a QC tools to clinical indication and of replacement of the film dosimetry. Aditional aim is to describe a procedure for the use of a EPID as a physics calibration tool in the measurements of radiation beam parameters which are typically carried out with film. Method & Materials : In this study we used the Clinac 2100c/d with EPID. This system contains 65536 liquid-filled ion chambers arranged in a $256{\times}256$ matrix and the imaging area is $32.5{\times}32.5cm$ with liquid layer thickness of 1mm. The EPID was tested for different field sizes under typical clinical conditions and pixel values were calibrated against dose by producing images using various thickness of lead attenuators(lead step wedge) using 6 & 10MV x-ray. We placed various thickness of lead on the table of linear accelerator and set the portal vision an SDD of 100cm. To acquire portal image we change the field size and energy, and we recorded the average pixel value in a $3{\times}3$ pixel region of interest(ROI) at field center was recorded. The pixel values were also measured for different field sizes in order to evaluate the dependence of pixel value on x-ray energy spectrum and various scatter components. Result : The EPID, as a whole, was useful as a QA tool and dosimetry device. In mechanical check, cross-hair centering was well matched and the error was less than ?2mm and light/radiation field coincidence was less than 1mm also. In portal dosimetry the wider the field size the the higher the pixel value and as the lead thickness increase, the pixel value was exponentially decreased. Conclusions : The EPID was very suitable for QA tools and it can be used to measure exit dose during patients treatment with reasonable accuracy. But when indicate the EPID to clincal study deep consideration required