• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.250.1-250.1
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• 2014

A multicusp ion source has been used widely in negative hydrogen cyclotrons mainly for radioisotope productions. The ion source is designed to have cusp geometries of magnetic field inside plasma chamber, where ions are confining and their mean lifetimes increase. The magnetic confinement produced a number of permanent magnetic poles helps to increase beam currents and reduce the emittance. Therefore optimizing the number of magnets confining more ions and increasing their mean lifetime in plasma has to be investigated in order to improve the performance of the ion source. In this work a numerical simulation of the magnetic flux density from a number of permanent magnets is carried to optimize the cusp geometries producing the highest plasma density, which is clearly indicated along the full-line cusp geometry. The effect of magnetic fields and a number of poles on the plasma structure are investigated by a computing tool. The electron confinement effect becomes stronger and the density increases with increasing the number of poles. On the contrary, the escape of electrons from the loss cone becomes more frequent as the pole number increases [1]. To understand above observation the electron and ion's trajectories along with different cusp geometries are simulated. The simulation has been shown that the optimized numbers of magnets can improve the ion density and uniformity.

• Journal of the Korean Society of Food Culture
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• v.19 no.6
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• pp.678-690
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• 2004

This study was implemented to offer materials for the activation of On-line food shopping mall though census about purchasing food. A percentage of people who had accessed to On-line food shopping mall was 53.8%, and who had an experience of purchasing food at the On-line sopping mali was 18.9%. The number of food purchasing in On-line food market is $1{\sim}3$ times(67.7%). It is general that an amount of food purchase is less than 100,000 wons. And the health assistant food is the most interesting item followed by Meet, Special products like a laver and mushroom, and an anchovy. in purchasing food at On-line market, customer thought that the confidence and the freshness of food are important because customer can't choose a product directly. In the future of food purchase using On-line shopping mall, 38.1% of people show their intend of purchasing at the mall. People who had experience of food purchase though the Internet have more positive view about repurchase than ones had not.

• Journal of the Korean Professional Engineers Association
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• v.42 no.3
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• pp.41-46
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• 2009

A new subway, line 9 linking Western and Eastern Seoul began its services for citizens between Gimpo airport and Gangnam area within 30 minutes by express transit service. Seoul Metro Line 9 Corporation plans to operate both local transit service which will stop at every station, and express transit service that will stop at several key stations including junctions. The passengers on line 9 will be able to transfer to lines 2, 3, 5, 8, Bundang and Incheon International Airport. The Line 9 is expected to disperse the demand for line 2, having the most number of subway users, and will provide passengers with less crowded travel. The new line will also help residents in southern Seoul outskirts and Gyeonggi provincial cities including Bundang vicinity, and Gangdong area commuters get better access to Gimpo and incheon Airports. The Corporation expects to transfer 560,000 passengers daily by the subway line 9. Seoul Development Institute conducted network reshuffle study for Seoul Metro system to sort out congestion problem due to its irrational line alignments and inconvenient transfer. Among several candidate plans of network reshuffling, the direct connection of line 9 with line 5 was chosen as a pilot study. The study found that direct connection of the 2 lines is essential for enhancing transit utility and reducing automobile commuters.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1240-1247
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• 1999

Particle motion through a disk type critical orifice placed in a 3.0cm diameter chamber has been studied numerically. In the simulation, the velocity field is solved using Pantankar's SIMPLER algorithm for the compressible flow and convergence of the computation is confirmed if the mass source at each control volume is smaller than $10^{-7}$. The particle motion in the flow field is solved in Lagrangian method. The particle trajectories showed that the particles injected away from the center line are expanded rapidly. At lower pressures, this expansion phenomena are more dominant. At lower pressures, the clear difference in particle and air speed is showed all the way down to the exit plan. It was found that particles with Stokes number of ca.2.5 tend to focus close to the center line very well except the particles travelling near the wall. However, particles with Stokes number greater than ca.2.5 show a tendency to cross the center line.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.74-78
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• 2002

In this study, We propose equations which can determine the number of sectionalizing switches for minimizing the outage and switch installation cost.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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• pp.2007-2016
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• 2011

In this paper, a new algorithm for alleviating overloads in power networks by the use of line power tracing and sensitivity is proposed to perform line switching and bus separation effectively. Also, a new bus separation index based on line power tracing is presented to find the bus to be separated for relieving overloads effectively. By applying the sensitivity of the line flow with respect to the change of the line impedance, both switching-on and switching-off of the lines for alleviating overloads in power networks are performed systematically at once. The number of the considered cases for line switching and bus separation can be greatly reduced and the best combination of line switching and bus separation can be acquired efficiently by the use of the sensitivity and the bus separation index. In order to show the effects of this algorithm, it is applied to a small scale power system of IEEE 39-bus system and practical power systems of KEPCO.

• International Journal of Highway Engineering
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• v.18 no.5
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• pp.127-134
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• 2016

PURPOSES : Visibility of lanes on the road improves as retro-reflectivity rises. This helps reduce traffic accidents at nighttime or in bad weather. This study aimed to evaluate the effects of improved visibility on reduction of traffic accidents when the color of the lane in the median of the highway was changed from yellow to white. METHODS : In order to evaluate the accident reduction effect of the white left shoulder line, Hauer (1997)'s Comparison-Group method was chosen as an analysis methodology. The JungBu-2 highway, which is equipped with the white left shoulder line and is in trial operation, was chosen as a target for analysis. Data of accidents for 10 months before and after installation was collected and analyzed. In addition to the number of accidents, the types of accidents were classified into nighttime accidents, accidents in bad weather, and median collisions. The accident reduction effect of improved visibility of lanes was analyzed. RESULTS : The analysis' finding showed that installation of the white left shoulder line decreased the number of accidents by 28%. Moreover, improvement in visibility was effective in reducing nighttime accidents by 67.63%, accidents in bad weather by 55.19%, and median collisions by 48.55%. CONCLUSIONS : Based on the analysis' results in this study, it was concluded that white left shoulder line on the freeway contributed to reduce traffic accidents, especially nighttime accidents, accidents in bad weather, and median collisions.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.2
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• pp.78-85
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• 2006

A survey on the fishing gear for octopus drift-line fishing was done in Gangwon-do, Sacheon, Gyeongnam and Hokkaido, Japan, while a survey on the environments of fishing grounds used data from January to August from the Korea east coast farming forecast system of Donghae Fisheries Research and Development Institute. The present situation of fishing was examined with boats engaging in drift-line fishing from March to August in the coastal waters along Gangneung. The fishing tackle for octopus drift-line fishing was made manually, and the size, shape, and weight of the hook and number of shooting used vary according to the fishing time and region. Lead is used as the material for sinkers. As bait, pork fat with skin is mostly used in Gangwon-do. The temperature of the bottom water layer in the coastal fishing ground of Gangneung from April to June ranges from $3.2-12.4^{\circ}C$, which is the optimal temperature for octopuses. During July and August, the temperature ranges from $5.0-20.6^{\circ}C$. The maximum difference between day and night temperatures reached up to $9.2^{\circ}C$. Salinity is generally stable at $33.2-35.324.6%_{\circ}$, which does not affect the inhabitation of octopuses. The octopus catch reached its peak from May to July, while most octopuses weighed less than 1 kg (76.7%). The results show that it is effective to carry out octopus drift-line fishing up to a depth of 40 meters; and that the maximum number of octopuses per line is obtained with an operation time of six hours.

• Fashion & Textile Research Journal
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• v.6 no.4
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• pp.497-502
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• 2004

The mechanical properties of jean slacks to the type of cutting lines in knee region and the bending time, after doing bending 0 times, 500 times, and 1500 times, the effects of whether or not cutting line, the fabric direction of the cutting area, and the number of cutting lines were investigated for tensile, shearing, compression, and mixing value of mechanical properties. The results are as follows: EM to bending times were larger in order of weft

• Journal of The Korean Astronomical Society
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• v.51 no.1
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• pp.5-16
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• 2018

We investigate the escape of $Ly{\beta}$ from emission nebulae with a significant population of excited hydrogen atoms in the level n = 2, rendering them optically thick in $H{\alpha}$. The transfer of $Ly{\beta}$ line photons in these optically thick regions is complicated by the presence of another scattering channel leading to re-emission of $H{\alpha}$, alternating their identities between $Ly{\beta}$ and $H{\alpha}$. In this work, we develop a Monte Carlo code to simulate the transfer of $Ly{\beta}$ line photons incorporating the scattering channel into $H{\alpha}$. Both $H{\alpha}$ and $Ly{\beta}$ lines are formed through diffusion in frequency space, where a line photon enters the wing regime after a fairly large number of resonance scatterings with hydrogen atoms. Various line profiles of $H{\alpha}$ and $Ly{\beta}$ emergent from our model nebulae are presented. It is argued that the electron temperature is a critical parameter which controls the flux ratio of emergent $Ly{\beta}$ and $H{\alpha}$. Specifically for $T\;=\;3{\times}10^4\;K$ and $H{\alpha}$ line center optical depth $\tau{\alpha}\;=\;10$, the number flux ratio of emergent $Ly{\beta}$ and $H{\alpha}$ is ~ 49 percent, which is quite significant. We propose that the leaking $Ly{\beta}$ can be an interesting source for the formation of $H{\alpha}$ wings observed in many symbiotic stars and active galactic nuclei. Similar broad $H{\alpha}$ wings are also expected in $Ly{\alpha}$ emitting halos found in the early universe, which can be potentially probed by the James Webb Telescope in the future.