• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.369-374
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• 2010

This paper presents a numerical investigation of the Deflagration to Detonation Transition (DDT) of flame acceleration by a shock wave in combustible gas mixture. A model consisting of the reactive compressible Navier-Stokes equations is used. The effects of viscosity, thermal conduction, species diffusion, and chemical reactions are included. Using this model, the generation of hot spots by repeated shock and flame interaction in front and back of flame and the change of detonation occurrence by various shock intensities (Ms=1.1, 1.2, 1.3) are studied. The simulations show that as the incident shock intensity increases, the Richtmyer-Meshkov (RM) instability becomes stronger and DDT occurrence time is reduced.

• Transactions of the Korean Society of Automotive Engineers
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• 제13권6호
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• pp.142-153
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• 2005

The brake judder is a phenomenon that the steering wheel is abnormally vibrating when the car is braked at a high speed. It is classified by the cold and the hot judder. The former is generated due to the initial uneven disk surface and the latter is resulted from the uneven heat spots on disc surface by repeatedly braking. There are two ways to reduce the judder. One is to control vibration by modification of the disk shapes and pad ingredients. The other is to improve modal characteristics of the suspension system. The latter approach is used in this research. In this paper, the real vehicle test and computer simulation are considered to systematically understand the judder phenomenon of the vehicle. The Macpherson strut suspension is employed. Especially, the judder sensitivity is calculated based on design sensitivity analysis. A bush stiffness was reworked and braking test was done to verify the sensitivity result. The judder reduction by the mode control was verified.

• Journal of the Korean association of regional geographers
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• 제21권3호
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• pp.583-592
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• 2015

As the increase of an environmental disease has become a social problem after industrialization, academic interest in a spatial difference and characteristics of an environmental disease is on rise. The purpose of this study is to analyze the spatial distribution and characteristics of an environmental disease using the data provided by National Health Insurance Corporation in 2009. This research is focusing on atopic dermatitis among a variety of environmental diseases and shows the map that atopic dermatitis patients are distributed. Also, The Local Moran's I show how spatial autocorrelation of atopic dermatitis patients are distributed. First, the distribution of atopic dermatitis patients show the spatial difference. Second, 42 places including the western part of Incheon are hot spots of atopic dermatitis. Third, 39 places including Danyang are cold spot of atopic dermatitis. Forth, Jeju-si and Seogwipo-si are unusually hot spot of atopic dermatitis. These results have important implications that further research need to be done in public health geography.

• Journal of KIISE:Computing Practices and Letters
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• 제7권1호
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• pp.38-47
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• 2001

PDM is an integrated solution for managing various kinds of document and information for a whole life~cycle of product management. PDM system spans a huge and complex area and requires so many efforts and budgets for development. A framework has been considered a promising way to improve productivity by reusing the software architecture, not just one part of the design or just source code. This was the reaSon why we developed PDM (Product Data Management) framework. Framework can reduce the time and efforts to develop a new PDM application. However, it also requires supporting environment since a framework is a big set of classes where their interactions are so complex. With this supporting environment, it is easy to understand the framework at a glance and easy to identify what hot spots to be refined to meet new requirements. In this paper, a new framework-supporting reuse environment based on the meta-repository was constructed for easy and convenient reuse.

• Journal of The Korean Astronomical Society
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• 제39권2호
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• pp.41-50
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• 2006

We present the results of new multi-color CCD photometry for the contact binary XZ Leo, together with reasonable explanations for the period and light variations. Six new times of minimum light have been determined. A period study with all available timings confirms Qian's (2001) finding that the O-C residuals have varied secularly according to $dP/dt\;=\;+8.20{\times}10^{-8}\;d\;yr^{-l}$. This trend could be interpreted as a conservative mass transfer from the less massive cool secondary to the more massive hot primary in the system with a mass flow rate of about $5.37{\times}10^{-8}\;M_{\odot}\;yr^{-l}$. By simultaneous analysis of our light curves and the previously published radial-velocity data, a consistent set of light and velocity parameters for XZ Leo is obtained. The small differences between the observed and theoretical light curves are modelled by a blue third light and by a hot spot near the neck of the primary component. Our period study does not support the tertiary light but the hot region which may be formed by gas streams from the cool secondary. The solution indicates that XZ Leo is a deep contact binary with the values of q=0.343, $i=78^{\circ}.8$, ${\Delta}(T_1-T_2)=126\;K$, and f=33.6 %, differing much from those of Niarchos et al. (1994). Absolute parameters of XZ Leo are determined as follows: $M_1=1.84\;M_{\odot},\;M_2=0.63\;M_{\odot},\;R_1=1.75\;R_{\odot},\;R_2=1.10\;R_{\odot},\;L_1=7.19\;L_{\odot},\;and\;L_2=2.66\;L_{\odot}$.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• 제33권4호
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• pp.221-229
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• 2015

The urban crimes that threat individual's safety are parts of the serious social problems. However. the information of crime in Korea has only been provided by forms of hot spots around place of crime, or forms of crime statistics without positional information. Those could not provide enough information to users in identifying the vulnerable areas for substantive crimes. Therefore, this study suggested a methodology of extraction in criminal vulnerable areas by using the spatial information, the statistical information and the public sector information. The crime vulnerable areas were extracted through the grid-based spatial analysis and the overlapping analysis from each of the information. In fact, the extracted areas were able to provide detailed vulnerability information than the traditional hot spot-based crime information. Following the study, the extracted results in crime vulnerable areas have displayed highly coincide with Korea safety map, provided by national disaster management institute, which regards to be able to provide crime risk rating in terms of administrative business in future.

• Journal of the Korean Association of Geographic Information Studies
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• 제25권2호
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• pp.100-109
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• 2022

Large-scale urban concentration of population and vehicles due to economic growth in Korea has been causing serious urban transport problems. Although the collection of congestion pricing has been evaluated as the most effective transportation policy to alleviate traffic demand, its effectiveness is very limited as it was just executed around congested points or along main arterial roads. This study derived dynamic congestion zones with the average travel speed of 206 traffic analysis zones in Busan Metropolitan City to propose a dynamic congestion pricing collection system by employing Space-Time Cube Analysis and Emerging Hot Spot Analysis. As a result, dynamic hot spots were formed from 7h to 24h and particularly, traffic congestion was severely deteriorated from 18h to 20h around Seomyeon and Gwangbok-dong. Therefore, it is expected that the effect of dynamic congestion pricing will be maximized in managing traffic demand in the city center.

• Proceedings of the Korean Information Science Society Conference
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• 한국정보과학회 2006년도 한국컴퓨터종합학술대회 논문집 Vol.33 No.1 (D)
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• pp.265-267
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• 2006

공용 주차장, 공항, 호텔, 쇼핑센터 등 로컬 회스폿 서비스들을 이용자의 별도 개입 없이 자동으로 제공받게 하려면 텔레매틱스 로컬 핫스폿 서비스에 대한 미들웨어가 필요하다. 본 논문에서는 이 미들웨어에 홈네트워크의 UPnP 미들웨어를 적용 제안하고 홈네트워크와 텔레매틱스 환경에서 UPnP의 차이점을 기술한다. 텔레매틱스 로컬 핫스폿 서비스 시나리오를 기술하고 UPnP의 서비스 발견에 대한 영향을 평가한다.

• Journal of the Korean Society of Safety
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• 제23권3호
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• pp.25-29
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• 2008

In automotive disc brake system, friction heat is not uniformly distributed due to various reasons such as thermal expansion and imperfections in geometry. It is well known that thermoelastic distortion due to fictional heating affects the contact pressure distribution and can lead to thermoelastic instability, where the contact load is concentrated in one or more small regions on the brake disc surface. These regions then take very high temperatures and passage of hot spots moving under the brake pads can cause low frequency vibration called brake judder. This paper presents the FEM(finite element method) result for the temperature distribution of ventilated disc brake. A steady state two-dimensional model of disc brake system predicts the surface temperatures during a multi-stop driving schedule.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.325-329
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• 2002

In this study, the dependency of the behavior of propagating front on the reaction condition in frontal polymerization reaction has been studied. We have used some multifunctional acrylates as a monomer and ammonium persulfate as an initiator for the polymerization reactions. In frontal polymerization, a method of producing polymeric materials via a thermal front that propagates through the unreacted monomer/initiator solution, the behavior of self propagating front shows various dynamic patterns depending on the reaction condition. We have obtained some spin modes of propagating front in the number of 'hot spots' or 'spin heads' by changing the reaction condition. The effect of the reactor tube diameter on the mode of propagating front has also been studied by using some reactor tubes with different size of tube diameter and it has been examined in some detail by adopting an experimental method of two-tubes system.