• 한국가시화정보학회:학술대회논문집
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• 2004.04a
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• pp.1-7
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• 2004

When a vortex diffracts upon encountering a vortex, many strong and weak waves are produced in the course of interaction. They are the cause of shock wave attenuation and noise production. This phenomenon is fundamental to understanding the more complex supersonic turbulent Jet noise. In this paper we have reviewed the research on shock-vortex interaction we have carried on last seven years. We have computationally investigated the parameter effect. When a shock is strong, shock diffraction pattern becomes complex since the slip lines from the triple points on Mach stem curl into the vortex, causing an entropy layer. When the vortex is unstable, vortexlets are brought about each of which make shock diffraction of a reduced intensity. Strong vortex produces quadrupole noise as it impinges into a vortex. Elementary interaction models such as shock splitting, shock reflection, and shock penetration are presented based on shock tube experiment. These models are also verified by computational approach. They easily explain production and propagation of the aforementioned quadrupole noise, Diverging acoustics are explained in terms of shock-vortexlet interactions for which a computational model Is constructed.

• The Journal of Korean Medical History
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• v.18 no.2
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• pp.15-37
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• 2005

In this paper, the overall contents of InJo's disease centering on the records from Chosun Dynasty's Official Records were examined. As a result, it was elucidated that the fundamental cause had lied in internal injuries of the Spleen and Stomach. The reason behind the constant change from fever to chills that agonized InJo the most lied not so much in external hazards as much in the injuries of the Spleen and Stomach. The treatment for InJo focused more on acupuncture methods than herbal medicine, which is thought to be characteristic of mid-Chosun Dynasty starting from the times of prior king SunJo or GwangHaeGun.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.341-347
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• 2003

Single flighted screw extrusion is the most cost effective method for the production of film, sheet, pipe and the fundamental step in other processes including blow molding and injection molding The temperature and injection pressure in barrel play a very important role in quality of products. Because thermal distortion and displacement of barrel by temperature difference and injection pressure difference cause irregular resine melting and flow. In this paper thermal distortion and stress of barrel includes pressure and temperature distributions by finite element analysis to understand dynamic characteristics of barrel.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2001.11a
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• pp.3-11
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• 2001

Fundamental studies at the CSIRO division of Wool technology and ICI on the diffusion of dyes into wool〔1,2〕have let to development of a new approach to wool dyeing. In this method, the cell membrane complex of wool is modified before dyeing by treatment under mildly alkaline conditions with a special chemicals. Wool pretreated with ethoxylated quaternary ammonium salt has an increased rate of dyebath exhaustion and dye penetration early in the dyeing cycle. This enables the treated material to be dyed below the boil for a similar time to the conventional cycle. This technique can be used on untreated and shrinkresist-treated wool and wool/nylon blends. In addition to good macro-levelness and excellent coverage of tippiness, the low temperature dyeing process give higher exhaustion levels of dyestuffs and insect-resist agent and hence cleaner effluent liquors, compared with conventional dyeing process. Low Temperature Dyeing process cause significantly less fiber damage than conventional way. The reduction in damage is reflected in improved processing performance of the dyed wool.

• Korean System Dynamics Review
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• v.1 no.1
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• pp.133-157
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• 2000

This paper deals with the social system from the point of system thinking consisting the fundamental construct of system dynamics. The Bertalanffy's general system theory, having been criticized because of its ambiguity, and the complex science theory, emerging system theory, are integrated by using the system thinking which is characterized with three concepts, 'feedback thinking', 'dynamic thinking', 'operational thinking'. In the integration, system thinking suggests the dynamic pattern of the social system have not only an equilibrium status but also complex status. The science of complexity gives an implication to system dynamics the important of the uncertainty and complexity if we interpret the social system as an open system. To show more concrete description, I simulate the cooperation model based on the iterated prisoner dilemma. The simulation results show the diverse patterns of cooperation and betrayal. Especially the sensitivity of initial payoff will cause the chaotic strategic landscapes as the game gose on. These results mean that we should not give the hasty prescription to control social system artificially. Because social system retains the self-organizing force in itself.

• The Journal of the Korean dental association
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• v.56 no.4
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• pp.218-230
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• 2018

According to the burst of aged people, researchers have focused on aging-related diseases. Cognitive impairment including Alzheimer's disease (AD), one of the representative diseases related to aging, has no treatment option until now. Recently, it has been revealed that systemic inflammation plays a fundamental role in the pathogenesis of AD. Previous studies have suggested the association between poor oral health and cognitive impairment. Poor oral health can cause dental caries, chronic periodontitis, multiple tooth loss, and poor chewing ability, etc. Especially, periodontitis is a well-known chronic inflammatory disease and affects cognitive impairment directly and indirectly by inflammatory products mediators. Therefore, reduction of pathogenic microbial burden and inflammatory products by treating periodontitis can be a therapeutic modality to prevent cognitive impairment or to slow down the progression of it. Future studies are necessary to elucidate the causal relations and plausible mechanisms between poor oral health and cognitive impairment.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1684-1686
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• 1998

Gas Insulated Switchgear(GIS) acts as an indispensible part in power transmission network. In order that GIS may have its high reliability, it is necessary to pay careful attention to its whole process e.g., designing, manufacturing, installation, and operation. The main hazard in GIS comes from free conducting particles, which can move and cause breakdown under the influence of the electric field. Although the concentration on protecting the GIS inner part against the free conducting particles is made, it is, actually, almost impossible to avoid the hazard from the particles throughly. In this paper, using the EHV test chamber, partial discharge quantity in GIS was measured when free conducting particles initiate to discharge for providing fundamental data for the purpose of developing predictive diagnosis technology on site GIS.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1801-1803
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• 1997

The Gas Insulated Switchgear(GIS) has made it an indispensible part of power transmission network. In order that the GIS may have its high reliability, it is necessary to pay careful attention to its whole process e.g., designing, manufacturing, installation, and operation. The main hazard in GIS comes from free conducting particles, which can move and cause breakdown under the influence of the electric field. Although the concentration on protecting the GIS inner part against the free conducting particles is made, it is, actually, almost impossible to avoid the hazard from the particles throughly. In this paper, the corona discharge in GIS initiated by the free conducting particles was discribed through laboratorial experiment The magnitude of the corona discharge voltage was measured using current measuring method by the impedance. The purpose of this experiment is to get fundamental data which is essential to develop GIS diagnosis technology.

• Journal of the Korean Ceramic Society
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• v.36 no.12
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• pp.1374-1380
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• 1999

The cause of Scond Harmonic Generation (SHG) in thermally poled silica glass is suggested basedon the electrical and dielectric relaxation measurements. The absorption currents as functions of time were measured for various types of silica glasses and analyzed by the theory of Space Charge Polarization. Space charge polarization occurs when an ionic conducting material is subjected to dc electric field with blocking electrode. Thermal poling performed to induce SHG in silica glass is basically identical to the process generating space charge polarization. Hence it was found that gene-ration removal reproduction and temperature dependence of SHG in poled silica is directly related to those of space charge polarization. It turned out that the fundamental parameters governing the SHG in poled silica are charge carrier concentration and mobility. Based on the theory of space charge polarization and experimental results of electrical rela-xation the method to increase the intensity of SHG is proposed.

• Earthquakes and Structures
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• v.9 no.6
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• pp.1181-1192
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• 2015

In this paper, an analytical method is proposed to study the effect of crack and axial load on vibration behavior and stability of the cracked columns. Using the local flexibility model, the crack has been simulated by a torsional spring with connecting two segments of column in crack location. By solving governing eigenvalue equation, the effects of crack parameters and axial load on the natural frequencies and buckling load as well as buckling load are investigated. The results show that the presents of crack cause to reduction in natural frequencies and buckling load whereas this reduction is affected by the location and depth of the crack. Furthermore, the tensile and compressive axial load increase and decrease the natural frequencies, respectively. In addition, as the compression load approaches to certain value, the fundamental natural frequency reaches zero and instability occurs. The accuracy of the model is validated through the experimental data reported in the literature.