• Journal of Energy Engineering
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• v.7 no.1
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• pp.113-121
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• 1998

In natural convection flows, the fluid velocities are highly dependent on the thermal field and property variations can have a strong effect on both the flow and thermal fields. To examine the effect of property variations, at first, numerical analyses covering wide range of the Prandtl number under the same Rayleigh numbers have been carried out. Next, we have modeled the viscosity and thermal conductivity as parabolic functions of temperature and a comprehensive set of numerical solutions have been obtained to understand the effect. The Prandtl number dependence of Nusselt number is fairly strong even though the effect is still weak compared to the Rayleigh number dependence. When thermophysical properties are dependent on temperature, the flow field showed a fairly weak variation except near boundaries, whereas the temperature field is strongly affected, especially by the temperature dependent thermal conductivity.

• Journal of the Korean GEO-environmental Society
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• v.10 no.5
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• pp.59-67
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• 2009

Three-dimensional (3D) numerical analyses have been conducted to study the behaviour of a single pile to tunnelling. The numerical analysis has included soil slip at the pile-soil interface. In the numerical analyses the interaction between the tunnel and the pile constructed in weathered soil and rock has been analysed. The study includes the pile settlement, the relative shear displacement between the pile and the soil and the shear stresses at the interface and the axial force on the pile. In particular, the shear stress transfer mechanism at the pile-soil interface related to the tunnel advancement has been rigorously analysed. Due to changes in the relative shear displacement at the pile-soil interface during the tunnel advancement, the shear stress and the axial force distributions along the pile have been changed. Upward shear stress developed at most part of the pile (Z/L=0.0-0.8), while downward shear stress is mobilised near the pile tip (Z/L=0.8-1.0) resulting in tensile force on the pile, where Z is the pile location and L is the pile length. Some insights into the pile behaviour to tunnelling obtained from the numerical analyses will be reported and discussed.

• The Journal of the Korea Contents Association
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• v.16 no.4
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• pp.594-603
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• 2016

This study analyzed that introduction function and program how influence about quality of life local resident and development of region according to real development. Also, it suggested policy implications of area activation plan through complex development of railway station area. In research method, the factor and structure affecting area activation in complex development of railway station area analyzed positively using the PLS structural equation focused on citizen near station area. As a result of study, in regional economic vitalization, the factors of software(marketing support, transfer system support, plan and design support, complex development support, law institution improvement, etc) and the factors of hardware(traffic function, information exchange function, commercial business function, housing features, amenity function, etc) are represented to influence significantly and then, in quality of life of local resident, the factor of hardware analyzed to influence significantly, but the factor of software and network did not. In comparison, the factor of network is represented that it did not contributed in regional economic vitalization and quality of life of local resident. So, political supplementations are needed.

• Journal of the Korean Geosynthetics Society
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• v.15 no.4
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• pp.89-96
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• 2016

Compressive axial behavior of the variable cross-section soft ground reinforced foundation is investigated from the field load test results at ${\bigcirc}{\bigcirc}$ construction site in Incheon city. Variable cross-section soft ground reinforced foundation is a type of partial-displacement pile formed by mixing bidding material with in situ soils to obtain a rigid and strong variable cross-section column in a relatively soft ground. The foundations are usually constructed as a group; however in this study, only single foundation was installed and tested under compressive axial load on foundation head. For the comparison of the variable cross-section soft ground reinforced foundation axial behavior, behavior of typical Pretensioned spun high strength concrete (PHC) pile constructed on a relatively soft ground near the surface was analyzed. It was concluded that variable cross-section soft ground reinforced foundation efficiently resists against axial load with sufficient stiffness and strength within a considerable range of axial load magnitude.

• Korean Journal of Digital Imaging in Medicine
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• v.10 no.2
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• pp.11-16
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• 2008

Images of medical treatment on PACS environment are digitized and they make saving and transmission of patient's information easy with CD format causing increase of patients transfer rate between hospital and data transmission as well. Figuring out the configuration of confining status of copied images of medical treatment with CD format and present the appropriate way of identification for personal information. 20 general hospital over 500 beds which are utilizing PACS currently. Questionnaire investigation focusing on PACS operation center and it's management people. In accordance with the law of securing personal information of public organizations, it says "Anyone who wants to see his or her information via representative he or she needs to make a letter of attorney and turn in this to the president of it's possessing facility" in the article 16. Based on the investigation of general hospital for CD copy issue status near metropolitan area, 8 out of 20, were issuing CD copy through personal identification process(the person oneself and representative) and 10 general hospital were doing by getting signature of receiptor only without identification of the person oneself and 2 general hospital confirmation process is not at all. By the law of securing personal information of public organization, article 16, confirmation process is supposed to mandate lawfully with a letter of attorney when there is any request of reading and/or copies of one's information. But in reality, there were no consistent rules on reading, the process and coverage of copy issue, rejection coverage of copy issue of CD copy in each general hospital PACS operation center. Therefore there is a big need for consolidated format which is applicable by law when the representative requests to issue of CD copy that is storing medical treatment images. By issue through this consolidated format, securing medical information of individual and systemic operation and management will be valid and effective.

• Journal of Biosystems Engineering
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• v.36 no.1
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• pp.23-32
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• 2011

In this work, the finite element method was used to investigate the shifts of resonance frequencies and quality factor of whispering-gallery-mode (WGM) for an opto-fluidic ring resonator (OFRR) biosensor. To describe the near-field radiation transfer, the time-domain Maxwell's equations were employed and solved by using the in-plane TE wave application mode of the COMSOL Multiphysics with RF module. The OFRR biosensor model under current study includes a glass capillary with a diameter of 100 mm and wall thickness of 3.0 mm. The resonance energy spectrum curves in the wavelength range from 1545 nm to 1560 nm were examined under different biosensing conditions. We mainly studied the sensitivity of resonance shifts affected by changes in the effective thickness of the sensor resonator ring with a 3.0 mm thick wall, as well as changes in the refractive index (RI) of the medium inside ring resonators with both 2.5 mm and 3.0 mm thick walls. In the bulk RI detection, a sensitivity of 23.1 nm/refractive index units (RIU) is achieved for a 2.5 mm thick ring. In small molecule detection, a sensitivity of 26.4 pm/nm is achieved with a maximum Q-factor of $6.3{\times}10^3$. These results compare favorably with those obtained by other researchers.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.9
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• pp.843-854
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• 2009

For preparing Korean lunar missions, optimal Earth-Moon transfer trajectory is designed using continuous low thrust. Using both constant and variable low thrusting method, "End-to-End" mission analysis is made from beginning of the Earth departure to the final lunar arrival. Spacecraft's equations of motion is expressed using N-body dynamics including the gravitational effects due to the Earth, Moon, Sun and also with Earth's $J_2$ effects. Planets' exact locations are computed accurately with JPL's DE405 ephemeris. As a results, optimal thrust steering angle's characteristics are discovered which showed almost tangential direction burns at the near of central planets. Also, it is confirmed that variable low thrusting method is more efficient than constant thrusting method, and can save about 5% of fuel consumption. Presented algorithm and various results will give numerous insights into the future Korea's Lunar missions using low thrust engines. Also, it is expected to be used as a basis of more detailed mission analyzing tool.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.2
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• pp.87-95
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• 1996

A questionary survey was performed to invetigate the citizen's attitude concerning the waste incineration facility. People disliked most cremetorim followed by waste transfer station, chmical factory, waste incineration facility and sanitary landfill. Most people favored 1km minimum distance of incineration facilities from the residence. Most people think that we need most composting facilities in the future followed by sanitary landfill and incineration facilities. Majority of people was willing to accept the perfect incineration facilities near their residence. However, 37.6% answered no. Most people accepted complusory measures by the goverment in the location of incineration facilites. One incineration facility per one city or Gun was slightly favored than multy-city or Gun incineration facility. People think that perfect thchnology most important to overcome Nimby's.

• Explosives and Blasting
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• v.25 no.2
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• pp.47-60
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• 2007

The blast demolition technology has been used to demolish various industrial facilities and tall buildings since 1950s in the advanced countries such as USA and U.K. It is now considered as one of safe demolition methods in the above countries. In Korea, several companies have tried to introduce blast demolition technology in the early days of the 1990s. However, this technology is still at the beginning stage and not fully adopted due to situation of avoiding technology transfer by overseas technical tie-up companies, lack of objects to be demolished and low level recognition on blast demolition. This technology shall be considered as a cutting edge technology to be applicable to demolition of skyscrapers, various industrial structures and factory buildings in the near future. Blast demolition of a pier structure was carried out under the site condition where there were already the constructed 2 pier structures of up and down line which had safety problems in an expressway construction project. The pier structures need to be demolished and reconstructed for a short period of time in consideration of the construction work process to be followed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.11 s.242
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• pp.1265-1276
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• 2005

The elliptic conceptual second moment models for turbulent heat fluxes, which are proposed on the basis of elliptic-blending and elliptic-relaxation equations, are applied to calculate the combined forced and natural turbulent convection in a vertical plane channel. The models satisfy the near-wall balance between viscous diffusion, viscous dissipation and temperature-pressure gradient correlation, and also have the characteristics of approaching its respective conventional high Reynolds number model far away from the wall. Also the models are closely linked to the elliptic blending model which is used for the prediction of Reynolds stress. In order to calibrate the heat flux models, firstly, the distributions of mean temperature and scala flux in fully developed channel flow with constant wall difference temperature are solved by the present models. The buoyancy effect on the turbulent characteristics including the mean velocity and temperature, the Reynolds stress tensor, and the turbulent heat flux vector are examined. In the opposing flow, the turbulent transport is greatly enhanced with both the Reynolds stresses and the turbulent heat fluxes being remarkably increased; whereas, in the aiding flow, the opposite change is observed. The results of prediction are directly compared to the DNS to assess the performance of the model predictions and show that the behaviors of the turbulent heat transfer in the whole flow region are well captured by the present models.