• Korean Journal of Social Welfare
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• v.60 no.3
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• pp.31-58
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• 2008

This study examines applying the elderly poverty labor hypothesis and skill-biased technological change hypothesis to labor force participation rate(LFPR) of older males in Korea. These hypotheses have hardly been examined on the this group. The analysis is based on the data "Summary of economically active population($1965{\sim}2007$)", "Population projection($1965{\sim}2007$)", "Report on wage structure survey($1993{\sim}2005$)" and "Korea Labor and Income Panel Study($1998{\sim}2006$)". The method employed for this study is logistic regression. The main results from this analysis are summarized in five points. Firstly, Korean older males' LFPR have been increasing since 1965 when industrialization was expanding at full steam. This trend has been different from the decreasing trend of industrialized countries. The second finding is that poor older males' LFPR is, on the average, 5.2% higher than that of non-poor older males from 1998 to 2005. The third result is that the non-elderly man has been increasingly positioned at higher grade occupations, while the elderly man has been held at lower grade occupations. The fourth is that labor demand for highly educated workers has exceeded the increased labor supply of the group, while the demand for low educated workers has decreased far beyond the declined labor supply. As a result, college premium has increased from 139% in 1993 to 157.8% in 2005. The final main implication of this study is that the industrialization theory and modernization hypothesis still holds for the LFPR of Korean older males. However, the elderly affluence hypothesis of the LFPR of older males are hardly persuasive in explaining Korean phenomenon. Especially, we find that the elderly poverty is the main mechanism in determining the Korean LFPR in old ages. This supports the elderly poverty labor hypothesis presented in this study. Skill-biased technological change hypothesis partially explains the LFPR of older man. However, we believe that other factors; human capital specially high school education rather than university education and skill required in less skill biased occupations or the poverty; also have taken effect.

• Journal of Life Science
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• v.30 no.3
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• pp.278-284
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• 2020

Magnolia kobus is known to exert various biological effects, such as antioxidant and hypnotic activity. In this study, we investigated the antimicrobial and anti-inflammatory activity of M. kobus essential oil extracted using steam distillation. Its antimicrobial activity was tested against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa by the paper disk diffusion and minimum inhibitory concentration (MIC) methods. Its anti-inflammatory activity was evaluated by measuring its inhibition ratio on the production of nitric oxide (NO) and PGE₂ in lipopolysaccharide (LPS)-induced RAW264.7 cells. Its composition was analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that M. kobus essential oil exhibited excellent antibacterial activity against S. aureus, with a clear zone of 18 mm and an MIC value of 0.25 mg/ml. Its clear zones against P. aeruginosa and E. coli were 14 mm and 17 mm, respectively, while its MIC values were 1 mg/ml and 0.5 mg/ml, respectively. The essential oil exhibited no cytotoxicity to the RAW264.7 cells at a concentration of 500 ㎍/ml while showing NO (37.7%) and PGE₂ inhibition (24.0%). Its three main fragrance ingredients identified were 3-carene (77.07%), β-elemene (6.92%), and caryphyllene (2.86%). The results suggest that M. kobus essential oil has potential as a cosmetic functional material with antimicrobial and anti-inflammatory effects.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.3
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• pp.389-396
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• 2018

The Kori-1 Nuclear Power Plant (NPP), WH 2-Loop Pressurized Water Reactor (PWR) operated for approximately 40 years in Korea, was permanently ceased on June 18, 2017. To reduce worker exposure to radiation by reducing the dose rate in the system before starting main decommissioning activities, the permanently ceased Kori-1 NPP will be subjected to full system decontamination. Generally, the range of system decontamination includes Reactor Pressure Vessels (RPV), Pressurizer (PZR), Steam Generators (SG), Chemical & Volume Control System (CVCS), Residual Heat Removal System (RHRS), and Reactor Coolant System (RCS) piping. In order to decontaminate these systems and equipment in an effective manner, it is necessary to evaluate the influence of the flow characteristics in the RCS during the decontamination period. There are various methods of providing circulating flow rate to the system decontamination. In this paper, the flow characteristics in Kori-1 NPP reactor coolant according to RHR pump operation were evaluated. The evaluation results showed that system decontamination using an RHR pump was not effective at decontamination due first to impurities deposited in piping and equipment, and second to the extreme flow unbalance in the RCS caused deposition of impurities.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.286-292
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• 2005

This study is to investigate the industrial boiler which can be significantly affected by the restriction of NOx. Note that the application of SNCR method to industrial boiler is usually blown as not feasible due to the insufficient residence time for proper mixing. The purpose of this study is to investigate the applicability of the SNCR system application to the industrial boiler, which produces 40 tons of steam per hour using heavy oil. For the industrial boiler with 3-D rectangular coordinate, the general coding are made fur various turbulence modeling such as turbulent flow, turbulent fuel combustion, thermal NO formation and destruction together with the NO reaction with reducing agents. Further, the incorporation of drop trajectory model is successfully made in 3-D rectangular coordinate with Lagrangian frame and the main swirl burner effect on the characteristics of flame is considered. As expected a short flame was created and thereby NOx is removed more efficiently by increasing the proper region of temperature for NO reduction reaction. The validation of program was made successfully by the comparison of experimental data. Based on the reliable calculation results, the SNCR method in a industrial boiler shows the possibility as one of viable NO reduction method by the use of well designed mixing air of reducing agent.

• Nuclear Engineering and Technology
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• v.25 no.2
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• pp.276-284
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• 1993

The ABB-CE System-80 reactor power cutback system(RPCS) is designed to enable continuous operation of the reactor without trip in the events of the loss of one of the two main feedwater pumps and loss of load, and thus improves plant availability in a cost effective manner. In this study expansion of RPCS has been investigated for continuous reactor operation without trip in the event of an inward control element assembly(CEA) deviation including a single rod drop. Under the expanded function of RPCS the control system will provide a rapid core power reduction on demand by releasing CEAs to drop into the core and reduce the turbine power, if necessary, to follow the reactor power variation. This design feature which is included as the new design features to be incorporated in the ABB-CE System-80+ meets the EPRI advanced light water reactor(ALWR) requirements. For this study core analysis models of System-80+ have been developed to simulate the nuclear steam supply system(NSSS) response as well as the RPCS initiation of rapid CEA insertion. The results of this study demonstrate that the reactor trip can be avoided in the event of inward CEA deviation including a single rod drop by the RPCS initiation and thus the plant availability and capacity factor would be increased.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.171-179
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• 2012

Cooling of hot sections, especially the turbine nozzle and rotor blades, has a significant impact on gas turbine performance. In this study, the influence of precooling of the cooling air on the performance of gas turbines and their combined cycle plants was investigated. A state-of-the-art F-class gas turbine was selected, and its design performance was deliberately simulated using detailed component models including turbine blade cooling. Off-design analysis was used to simulate changes in the operating conditions and performance of the gas turbines due to precooling of the cooling air. Thermodynamic and aerodynamic models were used to simulate the performance of the cooled nozzle and rotor blade. In the combined cycle plant, the heat rejected from the cooling air was recovered at the bottoming steam cycle to optimize the overall plant performance. With a 200K decrease of all cooling air stream, an almost 1.78% power upgrade due to increase in main gas flow and a 0.70 percent point efficiency decrease due to the fuel flow increase to maintain design turbine inlet temperature were predicted.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.543-549
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• 1997

The direct reaction of carbon dioxide($CO_2$) with butane($C_4H_{10}$) to obtain synthesis gas and hydrocarbon compounds have been studied on nickel loaded catalysts. In the reaction of $CO_2$ with $C_4H_{10}$, Ni loaded catalysts showed similar activity with Pt catalyst and Coke deposition on the catalyst was severe by dehydrogenation of butane. The main products were carbon monoxide and hydrogen, when alumina and Y type zeolite were used as a support. Instead, a great deal of aromatic hydrocarbons were obtained on the Ni loaded ZSM-5 catalyst. The conversion of $CO_2$ increased with the increasing molar ratio of $CO_2$/$C_4H_{10}$ on Ni/ZSM-5, Ni/NaY and Ni/alumina catalyst, but the conversion decreased again from the ratio of 2. The value of $CO_2$ conversion was the highest at the 5wt% of Ni loading on ZSM-5 catalyst. A part of cokes deposited on the catalysts diminished when only $CO_2$ gas or water steam flowed into the reactor. The coke deposited on the catalysts was very reactive and it may be an important intermediate for the carbon dioxide reforming reaction.

• Korean Journal of Plant Resources
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• v.9 no.1
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• pp.11-21
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• 1996

This study has observed the development, structure and distribution of oil canals in mitsuba, seri, ashitaba and hamabohu, that are condiment herbs belonging to the Umbelliferae family, using a light microscope. Oil canals were found in the petioles, leaf blades, stems, roots, hypocotyls and cotyledons. Oil classified into distribution due to ring vascular bundles, as in mitsuba and seri, and distribution due to diffuse vascular bundles, as in ashitaba and hamabohu. Oil canal development in the cortex due to petiole thickening was followed by the development of collenchyma and vascular bundles. However, no vascular bundles were formed in some cases. Many oil canals were found in the periphery of the petioles. Oil canals in leaf blades were found on the adaxial and abaxial sides on the veins. Those around the main veins were larger. Steam oil canals were found in the cortex and pith in mitsuba and seri, and in the cortex and fundamental tissues around the xylem, in ashitaba and hamabohu, while those in the roots were found in the pericycle in mitsuba and seri, and in the collenchyma-like tissues and phloem in ashitaba and hamabohu. The transverse sections of oil canals were round or elliptical. The secretory cells in the cortex and pith were smaller than the neighboring parenchyma cells, while they were larger than the neighboring parenchyma cells in the phloem.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.407-417
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• 2011

Nowadays, the high land use, mainly used for urbanization, is affecting runoff loads of non-point pollutants to increase. According to this fact, increasing runoff loads seems like to appear that it contributes to high ratio of pollution loads in the whole the pollution loads and that this non-point source is the main cause of water becoming worse quality. Especially, concentrated pollutants on the impermeable roads run off to the public water bodies. Also the coefficient of runoff from roads is high with a fast velocity of runoff, which ends up with consequence that a lot of pollutants runoff happens when it is raining. Therefore it is very important project to evaluate the quantity of pollutant loads. In this study, I computed the pollutant loadings depending on time and rainfall to analyze characteristics of runoff while first flush storm water and evaluated the runoff time while first flush storm water and rainfall based on the change in curves on the graph. I also computed contribution ratio to identify its impact on water quality of stream. I realized that the management and treatment of first flush storm water effluents is very important for the management of road's non-point source pollutants because runoff loads of non-point source pollution are over the 80% of whole loads of stream. Also according to the evaluation of runoff loads of first flush storm water for SS, run off time was shown under the 30 minute and rainfall was shown under the 5mm which is less than 20% of whole rainfall. These are under 5mm which is regarded amount of first flush storm water by the Ministry of Environment and it is judged to be because run off by rainfall is very fast on impermeable roads. Also, run off time and rainfall of BOD is higher than SS. Therefore I realized that the management of non-point source should be managed and done differently depending on each material. Finally, the contribution ratio of pollutants loads by rainfall-runoff was shown SS 12.7%, BOD 12.7%, COD 15.9%, T-N 4.9%, T-P 8.9%, however, the pollutants loads flowing into the steam was shown 4.4%. This represents that the concentration of non-point pollutants is relatively higher and we should find the methodical management and should be concerned about non-point source for improvement on water quality of streams.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.5
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• pp.557-565
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• 1992

Volatile components of domestic Meju and Doenjang were extracted by simultaneous steam distillation extraction, and analyzed by GC-MS. Sixty-four kinds of compounds were identified from neutral fraction. The contents of pentanal, hexanal and 1-octen-3-ol were high in cooked soybean while those of 3-methylbutanal and 1-butanol were high in Meju. In the case of Doenjang, so many compounds including acetic acid, ethylester were identified which was not appeared in Meju. The main compounds in Meju were 3-methyl-1-butanol, 2-furancarboxyaldehyde, 1-octen-3-ol, benzeneacetaldehyde, methyloctadecadienoate and methyloctadecenoate. Of the eleven compounds identified from basic fraction, the contents of 2,6-dime-thylpyrazine, trimethylpyrazine and tetramethylpyrazine were high in Meju and Doenjang. Nine kinds of compounds were identified from phenolic fraction and appeared that 4-vinylphenol and p-ethylguaiacol were major compounds in Meju and Doenjang. Fifteen kinds of volatile compounds were contained in acidic fraction. Only four acidic compounds were identified in cooked soybean and Meju, but in Doenjang ten compounds were identified which did not appeared in other samples. Among them pentadecanoic acid was major compound.