• Particle and aerosol research
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• v.12 no.4
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• pp.127-134
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• 2016

A multiwall carbon nanotube (MWCNT)/graphene (GR) composite was synthesized for an enhanced supercapacitor. Aerosol spray pyrolysis (ASP) was employed to synthesize the MWCNT/GR composites using a colloidal mixture of MWCNT and graphene oxide (GO). The effect of the weight ratio of the MWCNT/GO on the particle properties including the morphology and layered structure were investigated. The morphology of MWCNT/GR composites was generally the shape of a crumpled paper ball, and the average composite size was about $5{\mu}m$. MWCNT were uniformly dispersed in GR sheets and the MWCNT not only increase the basal spacing but also bridge the defects for electron transfer between GR sheets. Thus, it was increasing electrolyte/electrode contact area and facilitating transportation of electrolyte ion and electron in the electrode. Electrochemical data demonstrate that the MWCNT/GR (weight ratio=0.1) composite possesses a specific capacitance of 192 F/g at 0.1 A/g and good rate capability (88% capacity retention at 4 A/g) using two-electrode testing system.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.6
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• pp.1097-1108
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• 2019

In VLBI(Very Long Baseline Interferometry), the observed data created in many observatories which are far away from each other should be collected in correlation center for data analysis. Traditionally, observed data is moved by transportation such as car or airplane. But it is replaced with data transfer over the network rapidly as the advancement of information technology, and therefore, international cooperative research is also now more widely expanding. e-KVN(electronic Korean VLBI Network) has been upgraded two times so the network interface of KVN has been evolved to the highest specification of 100GbE. During this time period, the portion of network usage for VLBI observations and experiments in KVN has been increased exponentially. In this paper, we describe KVN VLBI system and network technology for the performance upgrade and advanced status monitoring between three radio astronomy observatories and Daejeon correlation center with KREONET(Korea Research Environment Open NETwork). Furthermore, future plan of e-KVN for the implementation of wide band VLBI observation will be also briefly discussed.

• Atmosphere
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• v.24 no.4
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• pp.471-479
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• 2014

A road surface temperature prediction model (UM-Road) using input data of the Unified Model (UM) output and road physical properties is developed and verified with the use of the observed data at road weather information system. The UM outputs of air temperature, relative humidity, wind speed, downward shortwave radiation, net longwave radiation, precipitation and the road properties such as slope angles, albedo, thermal conductivity, heat capacity at maximum 7 depth are used. The net radiation is computed by a surface radiation energy balance, the ground heat flux at surface is estimated by a surface energy balance based on the Monin-Obukhov similarity, the ground heat transfer process is applied to predict the road surface temperature. If the observed road surface temperature exists, the simulated road surface temperature is corrected by mean bias during the last 24 hours. The developed UM-Road is verified using the observed data at road side for the period from 21 to 31 March 2013. It is found that the UM-Road simulates the diurnal trend and peak values of road surface temperature very well and the 50% (90%) of temperature difference lies within ${\pm}1.5^{\circ}C$ (${\pm}2.5^{\circ}C$) except for precipitation case.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.1
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• pp.79-90
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• 2024

UAM is emerging due to the deepening population concentration in the metropolitan area and the problem of congested ground transportation in urban areas. Accordingly, along with research on eVTOL aircraft for UAM services, interest in vertiport, the interest in vertiports, the infrastructure that allows eVTOLs to take off and land, is also increasing. However, behind the concentration of population in the metropolitan area, aphenomenon of local extinction is occurring in conjunction with the aging population. AAM, which moves quickly through 3D space, can be an effective SOC facility in times of local extinction crisis. In this paper, we introduce a design plan from the perspective of a complex transper center for a regional hub-level vertiport that can connect with local high-speed rail and utilize local airports in compliance with the vertiport design guidelines issued by FAA(Federal Aviation Administration) and EASA(European union Aviation Safety Agency). We would like to present Vertiport's future operation plan.

• Neonatal Medicine
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• v.18 no.1
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• pp.137-142
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• 2011

Purpose: In relation to perinatal healthcare, medical institutions and resources are limitative and also are in a state of flux due to the therapeutic specialty. We analyzed requests for interhospital transfers received by Busan 1339 Emergency Medical Information Center (EMIC) to grasp the state of perinatal healthcare delivery system. Methods: This study was conducted on the basis of data inputted into the computing system of Busan 1339 EMIC, between January 1 and December 31, 2009. In connection with 378 pregnant women and 136 newborns who were required to transfer, retrospective analyses were made of the success rate of transfer (SR), the number of contacted hospitals, the time required for transfer and the reason of transfer and refusal. Results: In the case of pregnant women, the SR were 65.5%. They came in contact with 2.7 hospitals, and it took 24.4 minutes. As for the reason of transfer, preterm labor accounted for the highest proportion. In the case of newborns, the SR were 71.3%. They came in contact with 2.4 hospitals, and it took 15.6 minutes. The most common reason of transfer were respiratory symptoms. In the reason of refusal with pregnant women and newborn, the lack of medical staff, medical equipments and wards accounted for great. Conclusion: Many pregnant women and newborns have been transferred to hospitals by EMIC, but the SR has not been higher yet. Accordingly, there is a need to evaluate the propriety of perinatal treatment system, as well as to set up effective perinatal healthcare delivery system.

• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.28-39
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• 1998

This study investigated the natural convection and radiation in a rectangular enclosure with ceiling vent experimentally and numerically. A heat source is located on the center of the bottom surface. The analysis was peformed a pure convection and is combination of natural convection and radiation. The shape of the considered two dimensional model is a square whose center of ceiling($30\%$) is opened. The numerical simulations are carried out for the pure natural convection case and the combined heat transfer case by using the SIMPLE algorithm. For the turbulent flow, Reynolds stresses are closed by the standard $k-{\epsilon}$ model and the wall function is used to determine the wall boundary conditions. The experiment was performed on the same geometrical shape as the computations. The radiative heat transfer is analized by the S-N discrete ordinates method. The results of pure natural convection are compared with those of combined heat transfer by the velocity vectors, stream lines, isothermal lines. The results obtained are as follows 1. Comparing the results of pure convection with those of the combined convection-radiation through the shape of stream lines, isothermal lines are similar to each other. 2. The temperature fields obtained by numerical method are compared to those obtained by experimental one, and it is found that they are showed mean relative error $8.5\%$. 3. Visualization bt smoke is similar to computational results.

• Journal of Korean Port Research
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• v.6 no.1
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• pp.93-110
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• 1992

The most change in this century is supposed to be declination of ideology, and block of world economy. Addition to down full of cold war atmosphere around Northeast Asia, not only economic and social mood in this region is dramatically changed, but also it gave birth to the block of Northeast economy that accerlated new hub of world economy. According to dramatic change of economic surroundings the dynamic potential of growth in this region will be guided to enlarge inter-regional trade and increase volume of trade, thus suggests to grow steadily transportation. cargos in this region will have to arrange the system of delivery and inner transportation, accessary facilities, inter-regional harbors if North America and EC has connected easily. As have accerlated GATT and UR represented multilateralism and regionalism, it has regulated to increase trades of region due to relief of the trade barrier through specific areas has agreed with separately. The flow of regionalism of world economy has appeared to realize EC and NAFTA centered U.S.A, and also has presented to free trade region or one-size market agreement in Asia as APEC, EAEG in Malaysia, and etc. In defense to this block and internationalism of world economy, Pusan has to come forward to the hub of Northeast others has proposed a project to dominate the Northeast, Economy Association Agreement as Far East comprehensive development project in USSR, Hunchun development project in NK, and East Sea development project in PRC, Niigate regional development in Japan, Duman River development project in NK, and East Sea development project in Korea. As this exercise has proceed, Pusan also have arranged development strategy definitely and prepared provisions systematically. Engaging to participate center of delivery system is meant to be completed complex functions, namely the transfer storage processing & assembly function of international commodity. Pusan has ability to be terminal point of TSR. it had been connected to EC as the biggest economy block and TKR as complex transportation root to Far East, it would be the center of inground and seabase delivery terminal to Rotterdom as the biggest container pier and major piers to North-East and South East Asia. In order to provide a Role of 21 century's internationalization, Pusan has appealed to participate in management information research and development connected to Pohang-Ulsan-Changwon-Masan, and has utilized efficiently the resources such as man, material, money and information.

• Journal of Institute of Convergence Technology
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• v.2 no.1
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• pp.38-42
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• 2012

A scroll compressor used in the air conditioning in automobile consists of the fixed scroll and the orbiting scroll. Temperature gradient in the scroll compressor during the operation induces the thermal expansion of two scrolls. Therefore, the gap between scrolls in the initial stage is regarded as an important variable in structural design of the scroll compressor. The coupled thermal-stress analysis was carried out for the scrolls of a scroll compressor. The temperatures of major points of two scrolls in the steady states were referred by the literature of C. Lin. The sequentially coupled thermal-stress analysis is utilized to the heat transfer analysis and the thermal expansion analysis. In the thermal expansion analysis, the contact analysis was considered between the fixed and the orbiting scrolls in order to obtain the penetration distance and the contact pressure between two scrolls. The range of deformation was from 44 to $76{\mu}m$ according to the height of the scroll. The maximum penetration distance of $60{\mu}m$ occurred at the top surface of the fixed scroll in the center of the scroll parts.

• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.630-638
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• 2015

The total number of passengers on the KTX since its construction in 2004 surpassed 500 million in October, 2015. The operation of KTX made it possible to reach anywhere in a country in half a day, which subsequently altered people's lifestyle. As the KTX has become an important mode of transportation, there is a growing interest in the optimal size and location of its stations. Currently, the stations are constructed through public-private partnerships since a sufficient amount of budget is hard to secure only from the public sector; however, because railway stations are traditionally aimed at promoting public interests, an emphasis on the profitability of the private sector could compromise public interests. At this juncture, this study separately computes the number of users based on each of the two primary functions of the stations-as a railway station and as a sales facility-and estimates the numbers of people according to various transportation modes that are taken to access the stations. This estimation is applied to the case of Dongdaegu Station, which will open in 2016. Such an application helps to predict and respond to possible congestion as brought about by the expansion of the sales facility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1749-1755
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• 2014

Technique for analyzing a pile installed by vibrohammer was developed and parametric studies were executed in order to evaluate reliability of the developed technique. Comparing the accelerations obtained from parametric studies of varying eccentric moment and frequency, it can be seen that magnitude of maximum acceleration was proportional to the eccentric moment and square of frequency. It can also be seen that amplitude of displacement was roughly proportional to the eccentric moment but has nothing to do with the frequency. It can be said that all of the analysis results reflect characteristics of behavior of a pile in case of free vibration. Comparing the dynamic load transfer curves, maximum dynamic unit toe resistance was constant regardless of the eccentric moment and the frequency and it can be seen that dynamic unit skin friction was affected by the eccentric moment not by frequency. Comparing all of the analysis results, it can be said that the developed technique is reliable.