• Progress in Medical Physics
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• v.16 no.1
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• pp.24-31
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• 2005

The stereotactic radiosurgery (SRS) describes a method of delivering a high dose of radiation to a small tar-get volume in the brain, generally in a single fraction, while the dose delivered to the surrounding normal tissue should be minimized. To perform automatic plan of the SRS, a new method of multi-isocenter/shot linear accelerator (linac) and gamma knife (GK) radiosurgery treatment plan was developed, based on a physical lattice structure in target. The optimal radiosurgical plan had been constructed by many beam parameters in a linear accelerator or gamma knife-based radiation therapy. In this work, an isocenter/shot was modeled as a sphere, which is equal to the circular collimator/helmet hole size because the dimension of the 50% isodose level in the dose profile is similar to its size. In a computer-aided system, it accomplished first an automatic arrangement of multi-isocenter/shot considering two parameters such as positions and collimator/helmet sizes for each isocenter/shot. Simultaneously, an irregularly shaped target was approximated by cubic structures through computation of voxel units. The treatment planning method by the technique was evaluated as a dose distribution by dose volume histograms, dose conformity, and dose homogeneity to targets. For irregularly shaped targets, the new method performed optimal multi-isocenter packing, and it only took a few seconds in a computer-aided system. The targets were included in a more than 50% isodose curve. The dose conformity was ordinarily acceptable levels and the dose homogeneity was always less than 2.0, satisfying for various targets referred to Radiation Therapy Oncology Group (RTOG) SRS criteria. In conclusion, this approach by physical lattice structure could be a useful radiosurgical plan without restrictions in the various tumor shapes and the different modality techniques such as linac and GK for SRS.

• Journal of Chest Surgery
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• v.37 no.1
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• pp.35-42
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• 2004

Background: For the treatment of isolated left main coronary artery disease, twelve arterial revascularizations with Y-composite grafts using left internal thoracic artery and radial artery or right gastroepiploic artery were peformed. This study was performed to investigate whether V-composite graft can satisfy the blood flow required to make myocardium act properly or not. Borderline stenotic lesions on the left main coronary artery, which are very prone to remodel the bypassed vessels due to competitive flows, were also considered. Material and Method: Among 247 patients who underwent coronary artery bypass grafting from March 2000 to April 2003, 12 patients (4.7%) who had received total arterial revascularizations for the isolated left main coronary artery disease were studied retrospectively. Result: left anterior descending arteries were bypassed with left internal thoracic artery by off-pump technique in all patients, however, 2 cases of left obtuse marginal branches were bypassed under on-pump beating heart. Except for one patient, who did not have an obtuse marginal branch more than 1 mm in diameter, 11 patients had gone through complete arterial revascularizations by use of the Y shape arterial graft. Among five patients who had less than 75% stenosis, one patient showed string sign on left internal thoracic artery grafted to left anterior descending artery. However, two grafts to obtuse marginal blanches were completely obstructed and one showed slender sign. There were no graft-dominant flow in patients with stenotic lesion less than 75%. On the contrary to the result of patients with stenotic lesions less than 75%, all the patients with stenotic lesions more than 90% showed graft-dominant blood flow. Conclusion: In conclusion, it is assumed that, when stenotic lesions are over 90%, coronary artery bypass grafting with an Y shape arterial graft could possibly give enough help to the obstructed coronary arteries in blood supplying to myocardium, which needs massive quantity of blood to act well. However, when patients have borderline stenoses, through scrupulous examinations, more prudent and flexible decisions are required in choosing the treatment methods, such as, direct anastomosis of vein or artery to aorta, or adding supplementary treatment methods like percutaneous coronary intervention, rather than choosing a fixed treatment methods.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.511-515
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• 2012

In this study, we used a commercial simulator to investigate the gasification characteristics of Roto coal in the partitioned fluidized-bed gasifier, which consists of 4 parts such as coal pyrolysis, char gasification, tar/oil gasification and char combustion. The heating medium was exchanged between the combustion part and the gasification part in order to supply the energy needed for pyrolysis and gasification. The correlation model from experimental data in relation to the reaction temperatures, the reaction gases and the coal feed rates was derived for the coal pyrolysis. The equilibrium model was used for the gasification and the combustion model for the char combustion. In order to compare the reaction behavior of the partitioned fluidized-bed gasifier, the single-bed gasifier was also simulated. The cold gas efficiency of both partitioned fluidized-bed gasifier and single-bed gasifier was almost the same. The $H_2$ and $CH_4$ contents of the syngas in the partitioned fluidized-bed gasifier slightly increased and the CO and $CO_2$ contents slightly decreased, compared with the singlebed gasifier. In order to verify the model, ten cases of the single-bed gasification experiment have been simulated. The contents of CO, $CO_2$, $CH_4$ in the syngas from the simulation corresponded with the experimental data while those of $H_2$ was slightly higher than experimental data, but the tendency of $H_2$ content in the syngas was similar to the experiments. In the coal conversion, the simulation results were higher than the experiments since equilibrium model was used for the gasification so that the residence time and contact time in the model is different from the experiments.

• Clean Technology
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• v.20 no.4
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• pp.375-382
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• 2014

This work investigated the plasma-catalytic decomposition of isopropyl alcohol (IPA) and the behavior of the byproduct compounds over monolith-supported metal oxide catalysts. Iron oxide ($Fe_2O_3$) or copper oxide (CuO) was loaded on a monolithic porous ${\alpha}-Al_2O_3$ support, which was placed inside the coaxial electrodes of plasma reactor. The IPA decomposition efficiency itself hardly depended on the presence and type of metal oxides because the rate of plasma-induced decomposition was so fast, but the behavior of byproduct formation was largely affected by them. The concentrations of the unwanted byproducts, including acetone, formaldehyde, acetaldehyde, methane, carbon monoxide, etc., were in order of $Fe_2O_3/{\alpha}-Al_2O_3$ < $CuO/{\alpha}-Al_2O_3$ < ${\alpha}-Al_2O_3$ from low to high. Under the condition (flow rate: $1L\;min^{-1}$; IPA concentration: 5,000 ppm; $O_2$ content: 10%; discharge power: 47 W), the selectivity towards $CO_2$ was about 40, 80 and 95% for ${\alpha}-Al_2O_3$, $CuO/{\alpha}-Al_2O_3$ and $Fe_2O_3/{\alpha}-Al_2O_3$, respectively, indicating that $Fe_2O_3/{\alpha}-Al_2O_3$ is the most effective for plasma-catalytic oxidation of IPA. Unlike plasma-alone processes in which tar-like products formed from volatile organic compounds are deposited, the present plasma-catalyst hybrid system did not exhibit such a phenomenon, thus retaining the original catalytic activity.

• Journal of Animal Environmental Science
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• v.13 no.3
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• pp.211-218
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• 2007

This study was carried out to develop the technique for manufacturing activated carbon from livestock manure and to analyse it's odor absorptiveness. Each of layer manure(LM), litter from broiler house(BL) and litter from dairy barn(DL), compost from layer manure(LC) and pig manure(PC), and coconut shell(CS) was used as a raw material. Activated carbon by grinding the raw material, adding the coal tar as a binder, palletizing, drying, heating with $N_2$ gas at $400^{\circ}C$ for 1 hour, activating by reaction with steam at a temperature of $750^{\circ}C$ for 1 hour. Moisture contents of raw material was 44.9% in layer compost, 71.9% in layer manure, 24.4% in broiler litter, 47% in pig manure compost and 33.9% in dairy litter. Volatile matter in layer compost, layer manure, broiler litter, pig manure compost and dairy litter was 18.8%, 31.0%, 49.8%, 22.3% and 11.6%, respectively. Surface area(BET) of activated carbon from layer compost, layer manure, broiler litter, pig manure compost, dairy litter and coconut shell was 259.8, 209.8, 63.5, 442.3, 812.9 and $1,040\;m^2/g$, respectively. Activated carbon made by livestock manure or litter were examined with scanning electron microscope, and micropore was a type of sponge like particles honeycombed with chambers. Pore size of activated carbon was ranged from 0.39 to $5.02\;{\AA}$, but coconut shell was $0.30\;{\AA}$. Iodine absorptiveness of activated carbon from livestock manure was $530{\sim}580mg/g$. But activated carbon made by coconut shell was 1000 mg/g. Each activated carbon could absorb odor compound very well. Absorptiveness of activated carbon from layer manure for hydrogen sulfide and trimethyl amino was 74.5% and 73.9% at the accumulated flux of 60,000 ml, but, in the case of ammonia was only 15.2% at the accumulated flux of 10,000 ml

• Journal of Food Hygiene and Safety
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• v.27 no.4
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• pp.349-355
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• 2012

In this study, we configured a system which ranks hazardous chemicals to determine their management priorities based on experts' opinions and the existing CRS (chemical ranking and scoring). Aggregate exposure of food, health functional food, oriental/herbal medicine and cosmetics have been taken into account to determine management priority. In this study, 25 hazardous chemicals were selected, such as cadmium, lead, mercury, and arsenic, etc. These 25 materials were ranked according to their 1) risk (exposure or hazard) indexes, 2) exposure source-based weight, and 3) public interests, which were also formed based on the existing priority ranking system. Cadmium was scored the highest (178.5) and bisphenol A the lowest (56.8). Ten materials -- cadmium, lead, mercury, arsenic, tar, acrylamide, benzopyrene, aluminium, benzene, and PAHs -- scored higher than 100. Eight materials -- aflatoxin, manganese, phthalate, chromium, nitrate/nitrite, ethylcarbamate, formaldehyde, and copper -- recorded scores in the range from 70 to 100. Also evaluated as potential risks were 7 materials; sulfur dioxide, ochratoxin, dioxins, PCBs, fumonisin, methyl mercury, and bisphenol A, and these materials were scored above 50. Then we compared risk index and correlation coefficient of total scores to confirm the validity of the total scores; we analyzed correlation coefficient of parameter and indicator. We discovered that the total score and weight, which has incorporated public interests, were high and statistically significant. In conclusion, the result of this study contributes to strengthening risk assessment and risk management of hazardous chemicals.