• The Korean Journal of Pain
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• v.8 no.2
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• pp.324-327
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• 1995

Central serous chorioretinopathy is a relatively benign condition of young to middle-aged men, characterized by serous detachment of central retina as a consequence of focal leakage of fluid from the choriocapillaris through a defect in the retinal pigment epithelium. Approximately 80% of central serous chorioretinopathy undergo spontaneous resolution within 6 months. However 20 to 30% of patients with central serous chorioretinopathy have one or more recurrences and undergo chronic courses. In these cases laser photocoagulation is used to burn the leakage site directly, but there is no evidence that it reduces the chance of permanent loss of visual function and recurrence. We have administered stellate ganglion blocks (SGB) on a 43 year old male patient with central serous chorioretinopathy with multiple recurrences and experienced good results. We therefore recommend SGB as an effective treatment for central serous chorioretinopathy in conjunction with other ophthalmological treatments.

• Journal of Drive and Control
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• v.15 no.2
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• pp.32-37
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• 2018

The power plants use turbine output control devices to supply or shut off steam to high pressure and low-pressure steam turbines connected to generators. This turbine output control device is driven by a hydraulic servo actuator. The gas flows into the hydraulic servo actuator during periodic inspection or normal operation, and the resulting adiabatic compression of the gas raises the internal temperature of the actuator to $500^{\circ}C$. This temperature increase causes the seals to burn and show wear and tear, resulting in failure. In this study, an air vent valve was installed to allow gas inside the hydraulic servo actuator to flow large quantities of air at the beginning of the operation and after the periodic inspection. Gas was passed through for only minute flow during normal operation of the power plant. By applying the air vent valve, it improves the reliability of the hydraulic servo actuator by discharge the gas appropriately to improve the life of the seal.

• Journal of Environmental Health Sciences
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• v.26 no.2
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• pp.70-79
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• 2000

This study was done for the purpose of investigating the status of the use and perceptions of pesticides among the farmers who spray them in person. And it was also done to provide the basic statistics for the Agricultural Health Policy and study. Over the part of agricultural area in Kyungju and Ulsan City, Korea, from July to September 1999, 1032 questionnaires were distributed and 561 of them were collected and 447 were analysed. Major results of this study are as follows. The proportion of those who have special location for pesticides storage was only 5.3%, and that of those who lock hte storage location was only 13.6%. As to the treatment of bottles after use, most common response was 'burn in home'(47.7%). Most farmers purchase pesticides through 'pesticide store' or 'Agricultural Cooperatives'. The knowledge and Usage of pesticides depends in large part on experiences. The farmers who cultivate orchard spray pesticides more frequently than those cultivate paddy rice mainly. Most common pesticides in use are oganophosphates and carbamates. And also the pesticides that contains so-called 'Environmental Hormone' are used. The perception about the hazards of pesticides is rather superficial and insufficient. 'Herbicide(Gramoxon·Paraco)'(38%) is accepted as the most hazardous by farmers.

• Carbon letters
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• v.9 no.3
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• pp.200-202
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• 2008

In order to improve the thermal stability of PAN-based electrospun fibers, AP-PER-MEL and $TiO_2$ were added in to the fibers as additives. The polymer composite with uniformly mixed additional agents was obtained. In case of non-treated sample, the fibers were burn off completely with high rate within $620^{\circ}C$. But in case of treated samples (EF-M and EF-MT), it is sure that the thermal stability was improved by studying TGA data and ISO flammability test about 20 and 30%, respectively. A synergy effect of adding two kinds of agents (AP-PER-MEL and $TiO_2$) into PAN-based electrospun fibers was confirmed. Through SEM images, it is confirmed that the fiber shape can be kept even after addition of agents (AP-PER-MEL and $TiO_2$). Finally the thermal stability of fibers was largely developed with keeping the nature of PAN-based fibers effectively.

• Journal of the Korean Society of Safety
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• v.8 no.4
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• pp.165-174
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• 1993

For the safety assessment of the demonstration-scale incineration plant for treating the combustible radioactive wastes, radiation doses of a worker and a residential individual were estimated. The demonstration plant showed a good performance of trial-burn tests using non-radioactive tracers with resulting In high mass reduction of around 40 times and very low emmission of dusts through a stack, which promised a high decontamination factor in an order of 10$^{7}$ . Based on the result s obtained from the trial-burns in the process, the estimation of radiation dose for workers and general publics near the plant was made using dose pathway calculation theories. The parametric values for calculation were selected from design and operational results of the process and from more conservative conditions In reference data. The estimated annual doses for workers and residential indivisuals were 3.07 $\times$ 10$^{-4}$ and 4.35 X 10$^{-8}$ $\mu$Sv/y, respectively, which were high enough to operate the process when comparing with the allowable dose limit in the regulation. The dose calculation models were quite applicable with showing an excellent safety for the process.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.27-33
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• 1993

Using the solenoid driven gas injection valve, Hydrogen fuel supply system was made. It was attached to a single cylinder research engine and intake port injection type hydrogen fueled S.I. engine was constructed. Engine performance, emission characteristics, and abnormal combustion were studied through the engine test performed with the variations of fuel-air equivalence ratio and spark timing. Compared with gasoline, hydrogen burns so fast that cylinder peak pressure and temperature are higher and NO is emitted more at full load condition. IN the case of intake port injection type engine, COVimep becomes lower due to the well-mixing of air and fuel, and engine output is lower owing to the low volumetric efficiency. As fuel-air equivalence ratio goes up, the combustion speed increases, and COVimep decreases. NO emission peaks slightly lean of stoichiometric. As spark timing advances and fuel-air equivalence ratio goes up, the cylinder peak pressure and temperature become higher, so abnormal combustions take place easily.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.465-471
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• 2006

Controlled auto-ignition(CAI) combustion, offers the potential to improve fuel economy and reduce emission simultaneously. In this study, CAI-combustion was achieved in a single cylinder gasoline DI engine with modified camshafts in order to restrict the gas exchange process. We investigated the effects of air-fuel ratio, residual EGR rate and injection timing such as early injection and late injection on the attainable CAI combustion region. The effect of injection timings on combustion characteristic such as start of combustion, combustion duration and heat release rate was also investigated. From the result early injection causes the mixture to ignite earlier and burn more quickly due to the exothermic reaction during the recompression and gives rise to good mixing of the fuel/air. On the other hand, late injection extended the operation region more than early injection but the emissions of HC and NOx were more or less increased than early injection.

• Progress in Superconductivity and Cryogenics
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• v.23 no.4
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• pp.44-48
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• 2021

In order to obtain ultra-high resolution MRI images, research and development of 11 T or higher superconducting magnets have been actively conducted in the world, recently. The high-temperature superconductor (HTS), first discovered in 1986, was very limited in industrial application until mid-2010, despite its high critical current characteristics in the high magnetic field compared to the low-temperature superconductor. This is because HTS magnets were unable to operate stably due to the thermal damage when a quench occurred. With the introduction of no-insulation (NI) HTS magnet winding technology that does not burn electrically, it could be expected that the HTS magnets are dramatically reduced in weight, volume, and cost. In this paper, a 6 T-class NI HTS magnet for basic characteristic analysis was designed, and a distributed equivalent circuit model of the NI coils was configured to analyze the charging current characteristics caused by excitation current, and the charge delay phenomenon and loss were predicted through the development of a simulation model. Additionally, the critical current of the NI HTS magnets was estimated, considering the magnetic field, its angle and temperature with a given current. The loss due to charging delay characteristics was analyzed and the result was shown. It is meaningful to obtain detailed operation technology to secure a stable operation protocol for a 6T NI HTS magnet which is actually manufactured.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.281.1-281.1
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• 2002

Psoralen(7H-Furo［3.2-g］ ［1］benzopyran-7-one) and angelicin(2-Oxo-[2H]- furo[2.3-h]-1-benzopyran) are angular furocoumarin with diverse photobiological effects. They are major components of Psoralea corylifolia L.(破古紙). Psoralea corylifolia L. is used for a tonic and nursing one's energy. It can be also used for loss of virility. vitiligo. a skin disease, etc.. But a well known and often appreciated side effects f psoralens is the hyperpigmentation caused by this treatment. A women who used the herbal drug-mixed-medicine named'sobaeksu' to treat her vitiligo made a complaint against the orinetal medical doctor. She complained that her skin got burned to 2nd degree by the liquid. 'sobaeksu' through a medical celtficate. So we analyzed the components of that liquid with gas chromatography and gas chromatography/mass spectometry. It has 57.3% ethyl alcohol and two kinds of psoralens. Psoralens were psoralen and angelicin and each one of their contained quantity was 0.128mg/ml and 0.123mg/ml.

• Journal of Hydrogen and New Energy
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• v.33 no.5
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• pp.598-606
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• 2022

With the advancement of industry, the use of various sustainable energy sources and solutions to problems affecting the environment are being actively requested. From this point of view, it is intended to directly burn unused biogas to use it as energy and to solve environmental problems such as greenhouse gases. In this study, a new type of cavity matrix combustor capable of low-emission complete combustion without complex facilities such as separation or purification of biogas produced in small and medium-sized facilities was proposed, and CFD numerical calculation was performed to understand the performance characteristics of this combustor. The cavity matrix combustor consists of a burner with a rectangular porous microwave receptor at the center inside a 3D cavity that maintains a rectangular parallelepiped shape composed of a porous plate that can store heat in the combustor chamber. As a result of numerical calculation, the biogas supplied to the inlet of the combustor is converted to CO and H₂, which are intermediate products, on the surface of the 3D matrix porous burner. And then the optimal combustion process was achieved through complete combustion into CO₂ and H₂O due to increased combustibility by receiving heat energy from the microwave heating receptor.