• Resources Recycling
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• v.17 no.4
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• pp.47-56
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• 2008

The aim of this study is to produce cokes which can be used for the production of ferroalloy, for this purpose, domestic anthracite mixed with plastic was sintered at various condition. The combustion and physical properties of anthracite and plastic, coal separation, and the influence of factors on the strength of coke were investigated. The results of this study are as follows: 1. The three kinds of anthracite from the Samcheok region contained 25 to 30% ash of $100{\mu}m$ over size, and have the caloric value of 5,205 cal/g(TaeAn), 4,893 cal/g(JangSung), 4,873cal/g(KyongDong). 2. The recommendable conditions for heavy-fluid separation of the Samcheok coal are to set the specific gravity of heavy fluid to 2.4 and control the size of coal to $35{\sim}140mesh$. 3. It is concluded that phenolic resin powder, liquefied phenolic resin, SAN, and melamine resin can be used as a binder for the anthracite cokes, from the thermal analysis of various plastics. Especially, the liquefied phenolic resin was considered as the most suitable binder as it would simplify the process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1969-1975
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• 2013

ICN (Information-Centric Network) is a next generation Internet communication technology for converting existing Internet communication paradigm to information-based communication paradigm to efficiently use a large amount of information that exists on the Internet. Therefore, unlike existing Internet communication technologies focused on the process of communication using the host address, ICN focuses on the purpose of communication for each information by defining the information of everything that exists on the Internet. For this purpose, ICN uses NbR (Name-based Routing) methods that assign a name to each piece of information, all routers participating in ICN have the physical storage so that they are able to share information with each other. NbR methods on ICN are divided into one-phase routing and two-phase routing depending on how to reach at the storage of each router. However, currently proposed NbR methods cause many problems because they do not reflect the unique characteristics of ICN. Therefore, this paper looked at various NbR issues from caching, access time, distribution, mobility, scaliability, and dissemination of information for an efficient NbR method, and analyzed existing methods proposed for ICN. This paper also proposed a research direction to study the efficient NbR for ICN based on the analysis information.

• Journal of Sensor Science and Technology
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• v.1 no.2
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• pp.183-194
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• 1992

Some silicon micromechanical structures useful in sensors and actuators have been fabricated by electropolishing or porous silicon formation technique by anodic reaction in HF solution. The microstructures were lightly doped single crystal silicon and the formation was isotropic independent of crystal directions. Porous silicon layer(PSL) was formed selectively in $n^{+}$ region of $n^{+}/n$ silicon structure by anodic reaction in concentrated HF(20-48%) solution. Characteristics of the formed PSL were investigated along with change of the reaction voltage, HF concentration and the reaction time. PSL was formed only in $n^{+}$ region. The porosity of the PSL was decreased with the increase of HF concentration and independent of reaction voltage. For the case of $n/n^{+}/n$ structures, the etched surface of silicon was fairly smooth and a cusp was not found. The thickness of the microstructures was the same as that of the epitaxial n-Si layer and good uniformity. We have fabricated acceleration sensors by anodic reaction in HF solution(5 wt%) and planar technology. The process was compatible with conventional It fabrication technique. Various micromechanical structures, such as rotors of motor, gears and linear actuator, were also fabricated by the technique and examined by SEM photographs.

• Journal of the Korean Vacuum Society
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• v.16 no.5
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• pp.377-382
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• 2007

In this study, we report the synthesis of the single-walled carbon nanotubes(SWCNTs) using laminated catalyst(Al/Fe/Al) layer deposited by sputter on Si(001). SWCNTs are grown by thermal chemical vapor deposition (TCVD) method. As the results of scanning electron microscopy(SEM), high resolution transmission electron microscopy(HR-TEM) and Raman spectroscopy, we confirmed the SWCNTs bundles with narrow diameter distribution of $1.14{\sim}1.32\;nm$ and average G&D ratio of 22.76. Compare to the sample having Fe/Al catalyst layer, it can be proposed that the top-aluminum incorporated with iron catalyst plays an important role in growing process of CNTs as a agglomeration barrier of the Fe catalyst. Thus, we suggest that a proper quantity of aluminium metal incorporated in Fe catalyst induce small and uniform iron catalysts causing SWCNTs with narrow diameter distribution.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.2
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• pp.199-209
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• 2020

Purpose : This study used a sarcopenia diagnostic algorithm proposed by the Asia working group in adults over 50 to diagnose sarcopenia and analyze body function. The purpose of this study is to prepare basic data for the management and prevention of sarcopenia. Methods : We performed a diagnostic evaluation of sarcopenia in 97 adults over the age of 50 years with the cooperation of the Seongnam senior experience complex in Seongnam-si, Gyeonggi-do. As a result of the diagnostic process, 24 subjects were placed into the sarcopenia group, while 73 subjects were placed into the normal group. We measured each subject's body, performed the timed up and go test to evaluate functional mobility, and conducted a questionnaire on the pre-symptom of locomotive syndrome and locomotive syndrome. Results : There were statistically significant differences in height, weight, and skeletal muscle mass between the two groups. There was also a statistically significant difference in the timed up and go test, which confirmed the difference in functional mobility between the two groups. In addition, there was a statistically significant difference between the two groups in the proportion and the mean score of subjects with pre-symptom of locomotive syndrome and locomotive syndrome. In the correlation analysis, grip strength was statistically significantly correlated with height, weight, skeletal muscle mass, waist circumference, timed up and go test, pre-symptom of locomotive syndrome and locomotive syndrome. Gait speed was significantly correlated with the timed up and go test and locomotive syndrome. Appendicular skeletal muscle index was significantly correlated with height, weight, waist circumference, hip circumference, and the pre-symptom of locomotive syndrome. Conclusion : In conclusion, sarcopenia is closely related to height, weight, skeletal muscle mass and functional mobility, as well as the pre-symptom of locomotive syndrome and, locomotive syndrome. In consideration of this, the prevention and management of sarcopenia should be made accordingly.

• Fire Science and Engineering
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• v.31 no.6
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• pp.91-98
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• 2017

The present paper is a study on the tracking characteristics depending on accelerated degradation of PVC insulation material. In order to insulation degradation of PVC insulation material, the Arrhenius equation, a type of accelerated degradation test formula, was used to conduct accelerated degradation experiments with experiment samples prepared at the following age equivalents: 0, 10, 20, 30 and 40 years. Afterwards, a tracking experiment was conducted on the accelerated experiment samples as part of the KS C IEC 60112 criteria. When measuring the PVC tracking features according to the accelerated aging, the results showed that when 0.1% of ammonium chloride was added to the PVC insulating material, but no tracking occurred. However, depending on the age equivalent, The results of analyzing the current waveform and voltage waveform of the tracking propagation process showed the age equivalent from 0 years to 40 years displayed a break down in insulation resistance and even the BDB(before dielectric breakdown) sections did not maintain the same functionality of the original material. Based on a criterion of an age equivalent of 0 years, material with an age equivalent of 10 years posed a 1.4 times greater risk, material with an age equivalent of 20 years posed a 2 times greater risk, material with an age equivalent of 30 years posed a 4.6 times greater risk, and material with an age equivalent of 40 years posed a 7 times greater risk.

• Journal of Fisheries and Marine Sciences Education
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• v.5 no.1
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• pp.31-44
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• 1993

Through the early 1900's, the evolution of the surface condenser was closely tied to the development of steam engine and the turbine. As the chemical and petroleum industries evolved in the 1900's, the use of surface condensers in many different processes. Today, industry uses condensers in many shapes and sizes. The actual condensation process occurs on the outside surface of tubes. The nature of this surface geometry affects the condenser's heat transfer performance. The first condensers were built with plain tubes. As tube manufacturing techniques advanced, manufacturers started making tubes with integral fins. In the 1940's, fin densities were limited to about 600 to 700 fins per meter(fpm) because of manufacturing procedure. Today new manufacturing techniques allow production of tubes with fin densities ranging from 750 to 1600 fpm. The integral-fin tubes investigated in this paper are nominally 19 mm diameter. Eight tubes have been used with trapezodially shaped integral-fins having fin density from 748 to 1654 fpm and 10, 30 grooves. For comparison, tests are made using a plain tube having the same inside diameter and an outside diameter equal to that at the root of the fins for the finned tubes. Betty and Katz's theoretical modelis is used to predict the R-11 condensation coefficient on horizontal integral-fin tubes having 748, 1024 and 1299 fpm. Experiments are carried out using R-11 as working fluid. The refrigerant condensates at a saturation state of $30^{\circ}C$ on the outside tube surface cooled by coolant. The amount of noncondensable gases present in the test loop is reduced to a negligible value by repeated purging. For a given heat input to the boiler and given cooling water flow rate, all test data are taken at steady state. The observed heat transfer enhancement for the finned and grooved tubes significantly exceeded that to be expected on grounds of increased area. For the eight fin tubes and one plain tube tested, the best performance has been obtained with a tube having a fin density of 1299 fpm, and a fin bight of 1.2mm and 30 grooves.

• Membrane Journal
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• v.19 no.2
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• pp.165-171
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• 2009

This study was for the evaluation of adaptability of the fiber filter as the pre-treatment of the RO membrane through SDI (Silt Density Index) measurement. The turbidity of raw waters were $0.76{\sim}1.6$ NTU for the effluent of sewer treatment plants (STP) and $2.2{\sim}3.3$ NTU for sea waters and 100 NTU for the surface water. The turbidity of the $2^{nd}$ filtrate of the serially connected two fiber filters was $0.07{\sim}0.25$ NTU and $SDI_{15}$ was $1.4{\sim}2.8$ when the 17% PAC was dosed $10{\sim}30ppm$. Results of the turbidity and $SDI_{15}$ of the $2^{nd}$ filtrate of the fiber filter which were compared with them of the lab scale MF/UF disc filter for the same STP's effluents showed that filtrate quality were enhanced with a little on the order of two stage fiber filter>MF>UF, the difference in $SDI_{15}$ was only $0.7{\sim}1.0$. So, the filtrate of the serially connected two stage fiber filter could satisfy $SDI_{15}$ 5.0 safely which was normally required for the feed water by the RO membrane supplier and it means the serially connected two stage fiber filter could be applied as the pre-treatment process of the RO membrane.

• International Journal of Highway Engineering
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• v.17 no.3
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• pp.49-58
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• 2015

PURPOSES : The use of environmentally friendly construction methods has been recently encouraged to reduce fuel consumption and the effects of global warming. For this purpose, the roller compacted concrete pavement (RCCP) construction method has been developed. RCCP is more environmentally friendly and economically efficient than general concrete by reducing the amount of CO2 generated through the application of a smaller amount of cement. RCCP has a number of advantages such as an easy construction method, low cost, high structural hydration performance, and aggregate interlocking. However, mix design standards and construction guidelines of RCCP are required for domestic application. In addition, a study on aggregate selection, which has an effect on the characteristics of RCCP, is necessary owing to a limited number of researches. Thus, the aggregate effect on the performance of RCCP in securing the required strength and workability was evaluated in consideration of domestic construction. METHODS : Sand and coarse aggregates of both 19mm and 13mm in maximum size were used in this study. Four types of aggregate gradations (s/a = 30%, 58%, and 70% for the sand and coarse aggregate of 19mm in maximum size, and s/a = 50% for a combination of the three types of aggregates) were set up to investigate the effects of the PCA band on the RCC characteristics. The conditions of s/a = 30% and 70% were evaluated to check the gradation effect outside of the recommended band. The conditions of s/a = 58% and 50% were used because they are the optimum combination of the two and three types of aggregates, respectively. RCCP gradation band was suggested gradation with a proper construction method of RCCP by synthetically comparing and analyzing the correlation of optimum water content, maximum dry density, and strength of requirements through its consistency and compaction test. RESULTS : The lower and upper limit lines are insufficient to secure a relatively strong development and workability compared to an aggregate gradation in the RCCP gradation band region. On the other hand, the line in the RCCP gradation band and the 0.45 power curve in the RCCP gradation band region were satisfactory, ensuring the required strength and workability. CONCLUSIONS : The suitable aggregate gradation on RCCP process should meet the RCCP gradation band area; however, fine particles passing through a #60 sieve do not need to be within the recommended gradation band because the influence of this region on such fine particles is small.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.391-392
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• 2012

In these days, the desire for the precise and tiny displays in mobile application has been increased strongly. Currently, laser displays ranging from large-size laser TV to mobile projectors, are commercially available or due to appear on the market [1]. In order to achieve a mobile projectors, the semiconductor laser diodes should be used as a laser source due to their size and weight. In this presentation, the continuous etch characteristics of Pd and AlGaN/GaN superlattice for the fabrication of blue laser diodes were investigated by using inductively coupled $CHF_3$ and $Cl_2$ -based plasma. The GaN laser diode samples were grown on the sapphire (0001) substrate using a metal organic chemical vapor deposition system. A Si-doped GaN layer was grown on the substrate, followed by growth of LD structures, including the active layers of InGaN/GaN quantum well and barriers layer, as shown in other literature [2], and the palladium was used as a p-type ohmic contact metal. The etch rate of AlGaN/GaN superlattice (2.5/2.5 nm for 100 periods) and n-GaN by using $Cl_2$ (90%)/Ar (10%) and $Cl_2$ (50%)/$CHF_3$ (50%) plasma chemistry, respectively. While when the $Cl_2$/Ar plasma were used, the etch rate of AlGaN/GaN superlattice shows a similar etch rate as that of n-GaN, the $Cl_2/CHF_3$ plasma shows decreased etch rate, compared with that of $Cl_2$/Ar plasma, especially for AlGaN/GaN superlattice. Furthermore, it was also found that the Pd which is deposited on top of the superlattice couldn't be etched with $Cl_2$/Ar plasma. It was indicating that the etching step should be separated into 2 steps for the Pd etching and the superlattice etching, respectively. The etched surface of stacked Pd/superlattice as a result of 2-step etching process including Pd etching ($Cl_2/CHF_3$) and SLs ($Cl_2$/Ar) etching, respectively. EDX results shows that the etched surface is a GaN waveguide free from the Al, indicating the SLs were fully removed by etching. Furthermore, the optical and electrical properties will be also investigated in this presentation. In summary, Pd/AlGaN/GaN SLs were successfully etched exploiting noble 2-step etching processes.