• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.6
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• pp.847-854
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• 1999

In this paper, we have analysed frequency-dispersion characteristics of higher-order modes for uniform planar transmission lines, using the 2-dimensional finite-difference time-domain method. The method presented in this paper uses both informations of amplitude and phase of the electromagnetic spectrum to determine resonant frequencies, while methods previously reported use the magnitude only. This algorithm is very useful when a resonant mode has a relatively small magnitude, where the identification of the resonant mode is quite difficult. Numerical results show that a strip line supports few higher-order modes within the frequency range of 20 GHz, but there occur many higher-order modes in the structure of grounded coplanar waveguide, where resonant frequencies of the first higher-order mode is very close to those of the fundamental mode and there occur lots of very adjacent higher-order modes. As in this example, for the analysis of planar transmission lines which support many resonant modes very close each other, the method presented in this paper can be applied very efficiently.

• Journal of the Economic Geographical Society of Korea
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• v.17 no.4
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• pp.759-770
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• 2014

The aim of this study is to examine how time-use and activities are affected by work hours. To achieve this, we focused on the weekday time-use of full-time workers in Seoul Metropolitan Area(SMA). The long 'work hours' are under active discussions since it is related to the quality of life. However, many Social researcher thought that problem of Korean working hours is linked to quality of life in the abstract. Because activity connects time-use and quality of life, the key point is activity under time constraints. Therefore, travel patterns should be understood by time-use and activity patterns. This study composes trip-chains from travel data of 2010 Household Travel Survey(HTS). Grouping trip-chains by activity patterns, we could make sure that a few of activities after work is affected by a short free time. This study has potential implications for the policy of work hours and traffic problems in the evening, and will provide new geographical perspective related to measuring quality of life.

• Journal of the Korean Ceramic Society
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• v.34 no.8
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• pp.803-810
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• 1997

Ba0.5Sr0.5TiO3 thin films were deposited by RF magnetron sputliring method in order to clarify the anneal condition and doping effect on loakage current Nb and Al were selected as electron donor and acceptor dopants respectively, in the BST films because they have been known to have nearly same ionic radii as Ti and thought to substitute Ti sites to influence the charge carrier and the acceptor state adjacent to the gram boundary. BST thin films prepared in-situ at elevated temperature showed selatively high leakage current density and low breakdown voltage. In order to achieve smooth surface and to improve electrical properties, BST thin films were deposited at room temperature and annealed at elevated temperature. Post-annealed BST thin films showed smoother surface morphology and lower leakage current density than in-situ prepared thin films. The leakage current density of Al doped thin films was measured to be around 10-8A/cm2, which is much lower than those of undoped and Nb doped BST films. The result clearly demonstrates that higher Schottky barrier and lower mobile charge carrier concentration achieved by annealing in the oxygen atmosphere and by Al doping are desirable for reducing leakage current density in BST thin films.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.4
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• pp.1-8
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• 2014

Overexpanded flow of an axisymmetric thruster nozzle is numerically simulated to investigate effects of nozzle pressure ratio (NPR) on the shock structure and thrust performance. The Reynolds-averaged Navier-Stokes equations with k-${\omega}$ SST turbulence model are solved utilizing FLUENT solver. As the NPR is raised, thrust performance monotonically increases with the shock structure and flow-separation point being pushed toward the nozzle exit. It is also discussed that the flow structure at nozzle-exit plane which is immediately affected by a position of nozzle-interior shocks and expansion waves, has strong influence upon the thrust performance of thruster nozzle.

• Korean Journal of Materials Research
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• v.23 no.3
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• pp.206-210
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• 2013

In the segmented-in-series solid-oxide fuel cells (SIS-SOFCs), fabrication techniques which use decalcomania paper have many advantages, i.e., an increased active area of the electrode; better interfacial adhesion property between the anode, electrolyte and cathode; and improved layer thickness uniformity. In this work, a cell-stack was fabricated on porous ceramic flattened tube supports using decalcomania paper, which consists of an anode, electrolyte, and a cathode. The anode layer was $40{\mu}m$ thick, and was porous. The electrolyte layers exhibited a uniform thickness of about $20{\mu}m$ with a dense structure. Interfacial adhesion was improved due to the dense structure. The cathode layers was $30{\mu}m$ thick with porous structure, good adhesion to the electrolyte. The ohmic resistance levels at 800, 750 and $700^{\circ}C$ were measured, showing values of 1.49, 1.58 and $1.65{\Omega}{\cdot}cm^2$, respectively. The polarization resistances at 800, 750 and $700^{\circ}C$ were measured to be 1.63, 2.61 and $4.17cm^2$, respectively. These lower resistance values originated from the excellent interfacial adhesion between the anode, electrolyte and cathode. In a two-cell-stack SOFC, open-circuit voltages(OCVs) of 1.915, 1.942 and 1.957 V and maximum power densities(MPD) of 289.9, 276.1 and $220.4mW/cm^2$ were measured at 800, 750 and $700^{\circ}C$, respectively. The proposed fabrication technique using decalcomania paper was shown to be feasible for the easy fabrication of segmented-in-series flattened tube SOFCs.

• Journal of Korean Medicine for Obesity Research
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• v.15 no.2
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• pp.68-74
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• 2015

Objectives: The purpose of this study was to investigate the effects of Shengmai-san and Pyungwi-san, a herbal product used in traditional Chinese medicine, on gastrointestinal (GI) motility in mice. Methods: The in vivo effects of Shengmai-san and Pyungwi-san on GI motility were investigated by measuring the intestinal transit rates (ITRs) using Evans blue in normal mice and in mice with experimentally induced GI motility dysfunction (GMD). GMD was induced by injecting acetic acid or streptozotocin intraperitoneally. Results: In normal Institute of Cancer Research mice, ITRs were significantly and dose-dependently increased by Shengmaisan (0.01~1 g/kg) and Pyungwi-san (0.01~1 g/kg). The ITRs of acetic acid induced peritoneal irritation model and streptozotocin-induced diabetic model mice were significantly reduced compared to normal mice, and these reductions were significantly and dose-dependently inhibited by Shengmai-san (0.01~1 g/kg) and Pyungwi-san (0.01~1 g/kg). Conclusions: These results suggest that both Shengmai-san and Pyungwi-san are a good candidate for the development of a prokinetic agent that may prevent or alleviate GMD.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.536-545
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• 1997

The purposes of this study were to evaluate the degree of cavity cleanliness and to observe cavity wall morphology when root-end retrograde cavity preparation was done with ultrasonics. Root resections were done on 20 extracted human maxillary central incisors after canal filling with gutta-percha, and retrocavities were prepared using a slow-speed round bur as a control, and stainless steel ultrasonic tips of power settings of 2 and 6 ($Miniendo^{TM}$, EIE, SA, USA) as experimentals. The degree of the remaining cavity debris and smear layer, and wall morphology were evaluated under the scanning electron microscope. The results were as follows : Cavity prepared with ultrasonics of either power setting showed significantly less smear layer than did slow-speed preparations (p<0.01). However, there was no significant difference in canal debris (p<0.05). Cavity prepared with ultrasonics showed hatcheted appearance of wall, while slow-speed preparation showed relatively plain one.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.29 no.1
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• pp.145-156
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• 2016

Objective : We performed a literature review for developing the clinical phenotype evaluation system of atopic dermatitis.Methods : We searched the papers that describe symptoms for atopic dermatitis through Oriental Medicine Advanced Searching Integrated System(OASIS) and Korean Studies Incategoryation Service System(KISS). We looked through all the papers and finally chose 47 papers that are suitable for inclusion. Then, we extracted symptoms from these papers and arranged them in order of frequency and validity through experts' conference.Results : We found 360 papers and chose 47 papers. We decided to include general information of patients, systemic and dermatologic symptoms in evaluation category of atopic dermatitis. Through experts' conference, it was decided that general information has age, sex and body type; Systemic symptoms have 9 items; Dermatologic symptoms have 15 items.Conclusion : To evaluate atopic dermatitis objectively, the standardization of diagnostic tool is needed. Therefore we developed a clinical phenotype evaluation system of atopic dermatitis.

• Journal of the Korean Magnetics Society
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• v.10 no.5
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• pp.191-195
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• 2000

With the object of developing a non-gap choke core, effects of annealing in oxygen atmosphere on magnetic properties for Fe$_{78}$Si$_{9}$B$_{13}$ amorphous alloy were investigated. After annealing for 2 hrs at 440 $^{\circ}C$, optimum magnetic properties for choke core were obtained, where the effective permeability was 180 and was almost constant up to several MHz, and the decrease in permeability upon large DC bias current of 12 A or DC bias magnetic field of 8,000 A/m was very little. Moreover the AC magnetic loss was very low as compared to the conventional choke cores. Upon the optimum annealing, the magnetic hysteresis loop was inclined accompanying the increase of coercive force and the appearance of fine crystallites of $\alpha$-Fe phase. The good choke core properties was considered to be due to the suppression of domain boundary motion and domain refinement by the crystallites.

• Korean Journal of Acupuncture
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• v.32 no.2
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• pp.41-50
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• 2015

Objectives : In this study we investigated characteristics of eight extra meridians based on the chapter of Pyoung Gi Kyoung Pal Maek Byoung(PGKPMB) of the Pulse Classic(Maijing; PC) and the 27, 28, and $29^{th}$ question of the Classic of Difficult Issues(Nanjing; CDI). Methods : We searched out the contents of eight extra meridians in historical background, the principal and circulation of eight extra meridians, and the symptoms and pulse diagnosis of eight extra meridians on the PGKPMB of the PC and the 27, 28, and $29^{th}$ question of the CDI. Results and Conclusions : About development of eight extra meridians, content which was scattered in the CDI was supplemented and developed in the CDI. Also taking over the content in the CDI, the meaning of the eight extra meridians was expanded and supplemented in the PC. In the PC, the mechanism about symptom of eight extra meridians especially has been described. Also materialization of symptom which linked to pathogenic pulse of eight extra meridians had a great impact on future generation.