• Proceedings of the Korean Magnestics Society Conference
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• 2015.05a
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• pp.161-163
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• 2015

The micro device, coil, and channel for the biosensor integrated with the GMR-SV device based on the antiferromagnetic IrMn layer was fabricated by the light lithography process. When RBCs coupled with several magnetic beads with a diameter of $1{\mu}m$ passed on the micro channel, the movement of RBC + ${\mu}Beads$ is controlled by the electrical AC input signal. The RBC + ${\mu}Beads$ having a micro-magnetic field captured above the GMR-SV device is changed as the output signals for detection status. From these results, the GMR-SV device having the width magnitude of a few micron size can be applied as the biosensor for the analysis of a new magnetic property as the membrane's deformation of RBC coupled to magnetic beads.

• Proceedings of the KIEE Conference
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• summer
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• pp.113-116
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• 2004

Many methods to examine the vulnerable areal for the contingencies in the power system. The most widely used index for the vulnerable area investigation has been the reactive power margin or sensitivity analysis. But we can get the results of these analyses if only the results of load flow are convergent in severe contingencies, otherwise these methods are not adoptable. We can present a good index for overcoming severe contingencies, if we can get the vulnerable areas by bus sensitivity in severe contingencies, though the power flow equation is unsolvable. This paper simulates unsolvable severe contingencies by using branch parameter continuation power flow. We can compute the vulnerable areas in unsolvable severe contingencies by normal vector at a nose point of a $\nu-V$ curve. Presented method is checked the input reactive power of the vulnerable areas in KEPCO system.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.55.1-55.1
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• 2018

Studies on rotation-powered pulsars with strong surface magnetic field may help us clarify the unclear link between magnetars and canonical radio pulsars because the magnetar-like emission is expected to be observed. PSR J1119-6127 associated with SNR G292.2-0.5 has a high magnetic field of $4.1{\times}1013$ gauss, and a young characteristic age of ~1700 years can be served as the good candidate to compare with magnetars and rotation-powered pulsars. The glitch accompanied by the radiative changes detected in 2007 is the first case we observed for a rotationally powered radio pulsar. This pulsar experienced magnetar-like outbursts in mid. 2016, similar to the 2006 transition occurred on the other radio-quiet rotation-powered pulsar with strong surface magnetic field, PSR J1846-0258. In this talk, I'll report the investigation with X-ray and gamma-ray data of this magnetar-like pulsar. A sudden decrease in the gamma-ray emission at the GeV band was detected immediately after the X-ray outburst. Accompanying with the disappearance of the radio pulsation, the gamma-ray pulsation cannot be resolved as well after the outburst. We tried to derive the timing behavior and some intriguing features of this pulsar in this work corresponding to the outburst using the Swift data, NuSTAR and XMM observations.

• Journal of computational fluids engineering
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• v.19 no.1
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• pp.47-56
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• 2014

Since a typical plate heat exchanger is made up of a huge number of unitary cells, it may be impossible to predict the aero-thermal performance of the full scale heat exchanger through three-dimensional numerical simulation due to the enormous amount of computing resources and time required. In the present study, a simple flow-network model using the friction factor correlation and a thermal-network model based on the effectiveness-number of transfer units (${\varepsilon}$-NTU) method has been developed. The complicated flow pattern inside the cross-corrugated heat exchanger has been modeled into flow and thermal networks. Using this model, the heat transfer between neighboring streams can be considered, and the pressure drop and the heat transfer rate of full-scale heat exchanger matrix are calculated. In the calculation, the aero-thermal performance of each unitary cell of the heat exchanger matrix was evaluated using correlations of the Fanning friction factor f and the Nusselt number Nu, which were calculated by unitary-cell CFD model.

• Korean Journal of Community Nutrition
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• v.10 no.4
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• pp.471-483
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• 2005

The purpose of this study was to investigate food habits, nutrients intakes and nutritional quality of the preschool children living in Seoul. The study was performed by analyzing a questionnaire answered by the mothers of 233 subjects aged 2 to 6 years old. A three-day dietary intakes survey, using a 24 hour recall method was used by both the mothers and teachers of the children in day care centers. Twenty eight, 65.9 and $21.8\%$ of preschool children were underweight, normal and overweight or obese, respectively. It was found that $19.8\%$ of preschool children replied that they skipped breakfast sometimes. The major reasons for skipping breakfast were 'snacks' ($38.3\%$) and 'no appetite' ($32.6\%$). The proportion of subjects having unbalanced meals was $61.6\%$. From the 24-recall survey, it was found that all nutrients intakes were higher than those of the Korean RDA except zinc. The proportions of carbohydrate, protein and fat from total calories were 56,1, 17.2 and $30.7\%$. The P/M/S ratio was 0.62 : 0.86 : 1. Nutrient adquacy (NAR), mean of nu-trient adequacy ratio (MAR) and index of nutritional quality (INQ) were considered adequate. In conclusion, the dietary intakes of children aged 2 to 6 were assumed adequate judging from nutrient intakes, although some attention should be paid to fat intake in this age group.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.173-178
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• 2007

Time-lapse electrical resistivity measurements have been made in a scale model experiment for geological $CO_2$ sequestration in aquifer. Three types of $CO_2$ injection are tested in a water tank filled with glass beads. These are $CO_2$ dissolved into filtered tap water, $CO_2$ gas, and mineral oil. The mineral oil is a substitute for liquid phase of supercritical $CO_2$. For reconstructing three-dimensional resistivity images, we measure potential differences at 32 potential dipoles on the top surface of the tank due to two current dipoles on the front and back sides. The resultant resistivity images clearly show the movement of injected $CO_2$ in aquifer.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.4
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• pp.449-458
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• 2014

The heat transfer phenomenon was investigated in this study when a single round water jet with the low velocity and against the direction of gravity flows to the downward facing Isothermal of definite thickness circular plate. Experimental investigation is performed for a single round jet diameter 4mm, 6mm, and 8mm with the jet velocity 2.4m/s and jet fluid temperature of $24^{\circ}C$, varied the ratio of nozzle clearance/nozzle diameter (H/D)1, 2, 3, 6, and 8, on circular plate isothermal condition with $85^{\circ}C$. The local convection heat transfer coefficient distributions are analyzed based on the visualization of jet flow field. The effects of the diameter of Nozzle, the ratio of H/D and the ratio of nozzle diameter/circular plate diameter on heat transfer phenomenon are investigated. As a results of experiment is obtained correlation equation, $Nu_r=3.18Re_r^{0.55}Pr_r^{0.4}$.

• Journal of the Korean Home Economics Association
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• v.48 no.7
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• pp.77-87
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• 2010

This study investigated users' perceptions and attitudes toward Korean traditional elements in contemporary spaces. We collected and analyzed the article contents of two design magazines, from their issues of January 2000 through December 2009, for a total of 87 cases. The results were as follows. First, the important motives for applying traditional elements to current living spaces were individual tastes, preference for a secluded life, and the users' childhood memories. Second, the most frequently used traditional element was traditional structure. Others were traditional spatial compositions and the use of natural materials. The two main purposes for renovating a space or constructing a building were to preserve traditional ambience or to add convenience and practical use to it. Third, the most frequently mentioned advantages of traditional elements were their environment-friendly characteristics, such as connecting to nature and using natural materials. Fourth, the users preferred, in order, Ma-dang, natural environments, doors/windows of various types and multiple functions, Toet-maru, Dae-cheong, and Nu-maru.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.189-199
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• 2002

This study is intended to propose a systematic procedure for the development of the conditional assessment based on the safety of structures and the cost effective performance criteria for designing and upgrading of bridge structures. As a result, a set of cost function models for a life cycle cost analysis of bridge structures is proposed and thus the expected total life cycle costs (ETLCC) including initial (design, testing and construction) costs and direct/indirect damage costs considering repair and replacement costs, human losses and property damage costs, road user costs, and indirect regional economic losses costs. Also, the optimum safety indices are presented based on the expected total cost minimization function using only three parameters of the failure cost to the initial cost (${\tau}$), the extent of increased initial cost by improvement of safety (${\nu}$) and the order of an initial cost function (n). Through the enough numerical invetigations, we can positively conclude that the proposed optimum design procedure for bridge structures based on the ETLCC will lead to more rational, economical and safer design.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.4
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• pp.196-205
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• 2005

In this paper, recent research trend on heat transfer in impinging jet is reviewed. We focused on submerged jet that air issued into air or liquid issued into liquid. To control and enhance the heat transfer in single jet, researchers have performed a lot of experiments by considering the nozzle geometry, impinging surface and active method such as jet vibration, secondary injection and suction flow. The studies on multiple jet have been mainly focused on finding out the optimum condition and on investigating many different factors concerned with application condition (crossflow, rotation and geometry etc.) and combined techniques (rib turbulator, pin fin, dimple and effusion hole etc.). All most experiments showed the detailed heat transfer data by using liquid crystal method, infrared camera technique and naphthalene sublimation method. Many numerical calculations have been performed to investigate the flow and heat transfer characteristics in laminar jet region. Various turbulence models such as $k-\varepsilon-\bar{\nu^2}$, modified $k-\varepsilon-f_{\mu}$ were applied to the calculation for turbulent jet and the predicted results showed a good agreement with the experimental data. Although a lot of studies on impinging jet have performed consistently up to recently, further studies are still required to understand the flow and heat transfer characteristics more accurately, and to give a guideline for optimum impinging jet design in various applications.