• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.149-150
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• 1998

We have developed electrically driven portable ventilator and evaluated through in-vitro and in-vivo test. Ventilator is consists of DC servo motor(Kollmorgen), piston and ball screw, sensing system, power system with backup battery and micro controller. For the precise and stable volume control, the dynamic brake and the PI speed control loop is employed. The main functions are as followers; control, control+sigh, control/assist, control/assist+sigh and SIMV. The animal experiment showed stable performance when it is operated in control mode.

• 대한기계학회논문집
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• 제17권6호
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• pp.1609-1620
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• 1993

본 연구에서는 자연형 태양열시스템의 열성능에 영향을 미치는 인자를 열유동 전산해석을 통해 규명하고 모델을 설정하여 활용률을 최대로 하는 형상을 제시하고자 한다.

• International Journal of Aeronautical and Space Sciences
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• 제12권4호
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• pp.318-330
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• 2011

This paper investigates the convergence characteristics of the modified artificial compressibility method proposed by Turkel. In particular, a focus is mode on the convergence characteristics due to variation of the preconditioning factor (${\alpha}_u$) and the artificial compressibility (${\beta}$) in conjunction with an upwind method. For the investigations, a code using the modified artificial compressibility is developed. The code solves the axisymmetric incompressible Reynolds averaged Navier-Stokes equations. The cell-centered finite volume method is used in conjunction with Roe's approximate Riemann solver for the inviscid flux, and the central difference discretization is used for the viscous flux. Time marching is accomplished by the approximated factorization-alternate direction implicit method. In addition, Menter's k-${\omega}$ shear stress transport turbulence model is adopted for analysis of turbulent flows. Inviscid, laminar, and turbulent flows are solved to investigate the accuracy of solutions and convergence behavior in the modified artificial compressibility method. The possible reason for loss of robustness of the modified artificial compressibility method with ${\alpha}_u$ >1.0 is given.

• Computers and Concrete
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• 제26권1호
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• pp.11-20
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• 2020

Concrete are the most widely used manmade materials for infrastructure construction across the world. These constructions gradually aged and damaged due to long-term use. However, there does not exist an efficient concrete recycling method with low energy consumption. In this study, concrete was regarded as a heterogeneous material composed of coarse aggregate and cement mortar. And the failure mode of concrete under ultrasonic dynamic loading was investigated by finite element (FE) analysis. Simultaneously, a 3D random aggregate concrete model was programmed by APDL and imported into ABAQUS software, and the damage plastic constitutive model was applied to each phase to study the damage law of concrete under dynamic loading. Meanwhile, the dynamic damage process of concrete was numerically simulated, which observed ultrasonic propagating and the concrete crushing behavior. Finally, the FE simulation considering the influence of different aggregate volume and aggregate size was carried out to illustrate the damage level of concrete.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.2455-2462
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• 2008

Global warming has become one of the most important social responsibilities. After Kyoto protocol for greenhouse gas reduction by climatic change convention came into effect, developed countries are presenting various policies to reduce greenhouse gas that is produced in transport field. One of those policies is modal shift that change from road freight to sea, inland waterway and railway transportation that is eco-friendly. Because increase of road freight brings about road congestion and accident, logistics cost, air pollution and green house gases. Railways are superior to all other modes of transport in mass transportability, high speed, timeliness, safety and environmental-friendliness, but the railway industry has been pushed behind in competition. In developed country's government actively promoted relevant legislation, policies, and countermeasures known as modal shift policies to shift freight transport from road to large volume mode such as railway and ship. In this paper, we discuss the current situation in modal shift, compare it with cases in other countries EU and Japan, identify problems in Korea, and propose the following ways to enhance competitiveness of rail freight.

• Nuclear Engineering and Technology
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• 제40권7호
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• pp.551-560
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• 2008

Radiation has stochastic aspects in its generation, its choice of interaction mode during traveling in media, and its impact on living bodies. In certain circumstances, like in high dose environments resulting from low-LET radiation, the variance in its impact on a target volume is negligible. On the contrary, in low dose environments, especially when they are attributed to high-LET radiation, the impact on the target carries with it a large variance. This variation is more significant for smaller target volumes. Microdosimetric techniques, which have been developed to estimate the distribution of radiation energy deposited to cellular and subcellular-sized targets, contrast with macrodosimetric techniques which count only the average value. Since cells and DNA compounds are the critical targets in human bodies, microdosimetry, or dose estimation by microscopic approach, helps one better analyze the biological effects of radiation on the human body. By utilizing microbeam systems designed for individual cell irradiation, scientists have discovered that human cells exhibit radiosensitive reactions without being hit themselves (bystander effect). During the past 10 or more years, a new therapeutic protocol using discontinuous multiple micro-slit beams has been investigated for its clinical application. It has been suggested that the beneficial bystander effect is the essence of this protocol.

• 한국농공학회지
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• 제38권3호
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• pp.70-81
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• 1996

Solutions of geotechnical engineering problems require predictions of deformation and stresses during various stages of loading. Powerful numerical methods are available to make such predictions even for complicated problems. To get accurate results, realistic stress-strain relationships of soils are dependent on a number of factors such as soil type, density, stress level and stress path. Attempts are continuously being made to develope analytical models for soils incorporating all such factors. Isotropic compression-expansion test and a series of drained conventional triaxial tests with several stress path for Baekma river sand were performed to investigate stress-strain and volume change characteristics of Lade's single work hardening model dependant on the stress path. In order to predicted of stress-strain and volumetric strain behavior were determined the values of parameters for the mode by the computer program based on the regression analysis. Predicted stress-strain behavior of triaxial compression tests and optional stress path tests for increasing confining pressure with parameters obtained conventional triaxial compression tests agreed with several test results but the prediction results for decreasing confining pressure reduced triaxial compression tests make a little difference with test results.

• 한국동물위생학회지
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• 제34권3호
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• pp.285-289
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• 2011

This study was conducted to determine the content of non-steroidal anti-inflammatory drugs (NSAIDs) in meats available on the Korean markets. The analysis was carried out using following conditions; C18 column ($100{\times}2.1$ mm, 1.7 ${\mu}m$), mobile phase composed of DW (containing 0.1% formic acid): acetonitrile (containing 0.1% formic acid), binary pump at a flow rate of 0.3 ml/min and 5 ${\mu}l$ of injection volume, MS/MS detector with ESI positive mode. The calibration range of five NSAIDs showed linearity ($r^2{\geq}0.99$) at concentration range of 3.125~200 ${\mu}g$/kg. The recoveries in fortified muscle more than 78.7~100.3%. The detection limits for meloxicam, ketoprofen, flunixin, carprofen and tolfenamic acid were 3.5, 1.6, 1.7, 9.8 and 4.8 ${\mu}g$/kg, respectively. We also monitored NSAIDs residue in cattle muscle 51 samples. The test results, NSAIDs were all not founded.

• Advanced Composite Materials
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• 제16권2호
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• pp.95-113
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• 2007

Experimental investigations of interlaminar mechanical properties for carbon fiber reinforced plastic (CFRP) laminates were carried out using aramid fiber ($Kevlar^{(R)}$-29 1000d) and carbon fiber (TR40-1K 612d, Mitsubishi Rayon) stitching. Various carbon fiber (CF) stitch densities were used to prepare a number of CF stitched CFRP laminates for double cantilever beam (DCB) tests. An insert tongue-type loading fixture, developed by the Japan Aerospace Exploration Agency (formerly the National Aerospace Laboratory of Japan), was also employed in the DCB test. Interlaminar tension tests were carried out under an out-of-plane directional loading using a single CF stitch thread in the CFRP laminates. The DCB test results clarified that the relationship between the volume fractions of the CF stitch thread ($V_{ft}$) and mode I critical energy release rate ($G_{Ic}$) showed a mostly linear function with a higher gradient than that of the $Kevlar^{(R)}$ stitched CFRP laminates. The CF stitched CFRP tension test results indicated that the consumption energy per unit area ($E_i$) was larger than that of $Kevlar^{(R)}$ stitched CFRP laminates.

• 대한가정학회지
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• 제46권10호
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• pp.37-48
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• 2008

This study re-examines new aesthetic values pursued by Givenchy, analyzing by the Haute Couture line's chief designers. The following conclusions have been reached: Hubert de Givenchy pursued modernity, infused with simplicity and structured stability. In particular, Audrey Hepburn, who was a loyal client and used his line in several movies, provided him the platform for international exposure which he used to further develop what became known as the "Hepburn" style. The subsequent brief tenure of John Galliano did yield the fantastic and magnificent "Galliano-style", but with irregularity. Based on romanticism, it redefined fashion using a wide range of colors, subjects and decoration. His successor, Alexander McQueen, applied opposite elements using a hybrid technique of pastiche, parody and collage. With innovative inspiration he compromised the concepts of gender, time, space and cultures and recreated futuristic forms of nature, animals, insects and mythical images. Julien Macdonald, who was appointed in 2001 as the Artistic Director for the women's collections, minimized his individual style and preferred feminine, graceful and sexy silhouettes. He breathed fresh life in to Givenchy Haute Couture, reinterpreting the Hepburn style in a modernistic mode. Being passed on the responsibility for both collections (i.e., haute couture and ready-to-wear) in 2005, Riccardo Tisci redefined elegance, combining his unique and tailored gothic style with Givenchy's grace. He is developing the future of Givenchy, experimenting with volume, silhouettes, new kinds of fabric and techniques.