• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.2
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• pp.163-168
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• 2006

Improvement of crop yield can be achieved through understanding genetic variation in reproductive characters and its impact on yield components. The present study was performed to evaluate genetic diversity for reproductive growth characters in exotic germplasm resources and to determine the relationships between developmental and growth periods with yield and yield components in soybean cultivar groups. For phenotypic evaluation such as reproductive and agronomic traits, a total of 80 indigenous and exotic soybean cultivars collected from four different geographical regions (China, Japan, Korea, and Vietnam) were grown from May to November of 2003 at the Seoul National University Farm, Suwon, Korea ($127^{\circ}02'E$ longitude, $37^{\circ}26'N$ latitude). Most of all the characters exhibited wide range of phenotypic variation, of which pod number, seed number, and plant yield showed greater range as compared to other characters. Korean cultivar groups showed greater diversity than the other cultivar groups in seven characters. Correlation analysis showed that days to flowering (DTF) and days to maturity (DTM) had close association with agronomic traits as well as yield and yield components. Both DTF and DTM had positive correlation with the other characters except one hundred seed weight. Stepwise multiple linear regression revealed that seed and pod number were identified as being significant for plant yield. The results in this study indicated wide variation in agronomic traits including DTF and DTM, suggesting the valuable genetic resources in a soybean breeding program.

• Journal of the Korean Society of Combustion
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• v.22 no.4
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• pp.19-26
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• 2017

This study investigates the gasification of coal char by $CO_2$ under high pressures in a drop tube furnace(DTF). The rate constants are derived for the shrinking core model using the conventional method based on the set reactor conditions. The computational fluid dynamic(CFD) simulations adopting the rate constants revealed that the carbon conversion was much slower than the experimental results, especially under high temperature and high partial pressure of reactants. Three reasons were identified for the discrepancy: i) shorter reaction time because of the entry region for heating, ii) lower particle temperature by the endothermic reaction, and iii) lower partial pressure of $CO_2$ by its consumption. Therefore, the rate constants were corrected based on the actual reaction conditions of the char. The CFD results updated using the corrected rate constants well matched with the measured values. Such correction of reaction conditions in a DTF is essential in deriving rate constants for any char conversion models by $H_2O$ and $O_2$ as well as $CO_2$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.12
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• pp.963-969
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• 2014

Four coal sources that had different ash contents were evaluated in a drop tube furnace (DTF). Combustion experiments were conducted by using several sources with different particle sizes and excess air ratios under air-staging conditions to determine the optimized combustion conditions of high-ash coal, with an emphasis on the combustion efficiency and NOx emissions. The results show that the higher ash content results in a large amount of carbon remaining unburned, and that this effect is dominant when the largest particle size is used. Furthermore, the ash content of coal does affect the Char-NOx concentration, which decreases with the particle size. The results of this study suggest that an air-staged system can be useful to reduce the NOx emissions of high-ash coal and that control of the air stoichiometric ratio of the primary combustion zone (SR1) is effective for reducing NOx emissions, especially by considering unburned carbon contents.

• Journal of IKEEE
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• v.26 no.2
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• pp.257-264
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• 2022

As it takes a lot of time and money to develop an aircraft, an environment for renovating and using existing operating aircraft has been created. As a result, many old aircraft were renovated, and due to the aging of the aircraft, more demanding cable requirements were required for renovation projects, and as the number of equipment inside the aircraft gradually increased, the difficulty of system integration increased. In order to solve the difficulties of system integration through systematization of verification procedures, this paper explains VSWR, I-loss, which are the main indicators of antenna cable modification, and explains DTF, one of the problem detection methods. It also explains the elements required for cable design, the environment to be measured, and procedures, and introduces the overall process and effect of antenna cable improvement through demonstration cases.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.6
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• pp.420-425
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• 2011

In general, the decomposition of $CaSO_4$ formed by sulfation reaction in the in-furnace desulfurization process using limestone has strong effect on the desulfurization reaction under the oxy-fuel combustion condition. In this study, the conversion rates were measured and reaction rates were calculated in order to investigate the effects of the experimental variables such as temperature and the concentrations of $CO_2$, $O_2$, $SO_2$, on the $CaSO_4$ decomposition reaction using DTF (Drop Tube Furnace) in the desulfurization reaction. The conversion rate and the reaction rate of $CaSO_4$ decomposition reaction were increased with reaction temperature. $CO_2$ concentration has little effect on $CaSO_4$ decomposition reaction in the presence of $O_2$. Under the same experimental conditions, the decomposition rate of $CaSO_4$ was enhanced with the decreasing the $O_2$ concentration, but vice versa with the increasing of $SO_2$ concentration.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.1
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• pp.31-37
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• 2016

Co-firing of biomass with coal is a promising combustion technology in a coal-fired power plant. However, it still requires verifications to apply co-firing in an actual boiler. In this study, data from the Thermogravimetric analyzer(TGA) and Drop tube furnace(DTF) were used to obtain the combustion characteristics of biomass when co-firing with coal. The combustion characteristics were verified using experimental results including reactivity from the TGA and Unburned carbon(UBC) data from the DTF. The experiment also analyzed with the variation of the biomass blending ratio and biomass particle size. It was determined that increasing the biomass blending ratio resulted in incomplete chemical reactions due to insufficient oxygen levels because of the rapid initial combustion characteristics of the biomass. Thus, the optimum blending condition of the biomass based on the results of this study was found to be 5 while oxygen enrichment reduced the increase of UBC that occurred during combustion of blended biomass and coal.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.89-96
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• 2015

Recently, much research has been put into finding the causes and solutions of slagging/fouling problems that occur at the end of the boiler. This slagging/fouling, caused by low-rank coal's ash, disturbs the thermal power and greatly reduces efficiency. In environmental aspects, such as NOx pollution, governments have been implementing restrictions on the quantity of emission gases that can be released into the atmosphere. To solve these problems, research on Ash Free Coal (AFC), which eliminates ash from low-rank coal, is in progress. AFC has advantages over similar high-rank coals because it increases the heating value of the low grade coal, reduces the contaminants that are emitted, and decreases slagging/fouling problems. In this study, using a DTF, the changes of NOx emissions, unburned carbon, and the characteristics of ash deposition were identified. KCH raw coal, AFC extracted from KCH, residue coal, Glencore, and Mixed Coal (Glencore 85wt% and residue coal 15wt%) were studied. Results showed that AFC had a significantly lower emission of NOx compared to that of the raw coal and residue coal. Also, the residue coal showed a higher reactivity compared to raw coal. And finally, In the case of the residue coal and mixed coal, they showed a lower ash deposition than that of low-rank coal.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.997-1003
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• 2011

In order to investigate devolatilization characteristics for ashless coal with relatively low ash content and high heating value, an experiment was performed in different bed configurations of TGA and DTF(Drop Tube Furnace) at atmospheric pressure condition. The heating rate was $10^{\circ}C$/min up to $950^{\circ}C$ in TGA, while the temperatures of DTF varied from 500 to $1300^{\circ}C$ in step of $200^{\circ}C$. A weight loss and particle temperature were obtained to determine devolatilization kinetics. The kinetic parameters including an activation energy and pre-exponential factor for ashless coal were obtained using Coats-Redfern method in TGA and single step method in DTF. Furthermore, the devolatilization kinetics of the ashless coal were compared with the results of different kinds of conventional coal such as sub-bituminous and bituminous. The results show that the activation energy of devolatilazation for ashless coal is lower than those of others in fixed and entrained conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.3
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• pp.246-268
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• 2019

Soybean [Glycine max (L.) Merr.] is a species of legume native to East Asia. The interactions between climatic conditions and genetic characteristics are known to affect the agricultural performance of soybean. Therefore, the present investigation was conducted to identify the main elements affecting the agricultural performances of 11 soybean varieties/lines from China [Harbin ($45^{\circ}12^{\prime}N$), Yanji ($42^{\circ}53^{\prime}N$), Dalian ($39^{\circ}30^{\prime}N$), Qingdao ($36^{\circ}26^{\prime}N$)] and the Republic of Korea [Suwon ($37^{\circ}16^{\prime}N$), and Jeonju ($35^{\circ}49^{\prime}N$)]. The days to flowering (DTF) of soybeans with the e1-nf and e1-as alleles and the E1e2e3e4 genotype, except in 'Keumgangkong', 'Tawonkong', and 'Duyoukong', were relatively short compared to those of soybeans with other alleles. Although DTF of the soybeans was highly correlated with all climatic conditions [negative: precipitation, average temperature (AVT), accumulated temperature; positive: day-length (DL)], days to maturity and 100-seed weight of the soybeans showed no significant correlation with any climatic conditions. The soybeans with a dominant Dt1 allele, except 'Tawonkong', had the longest stem length (STL). Moreover, STL of the soybeans grown in the test fields showed a positive correlation with only DL; however, the results of our chamber test that was conducted to complement the field tests showed that STL of soybean was positively affected by AVT and DL. Although soybean yield (YLD) showed positive correlations with latitude and DL (except L62-667, OT89-5, and OT89-6), the response of YLD to the climatic conditions was cultivar-specific. Our results show that DTF and STL of soybeans grown in six different latitudes are highly affected by DL, and AVT and genetic characteristic also affect DTF and STL.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.613-614
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• 2010