• The KSFM Journal of Fluid Machinery
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• v.2 no.3 s.4
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• pp.45-51
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• 1999

Centrifugal fans are widely used and the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the casing. However, only a few researches have been carried out on predicting the noise due to the difficulty in obtaining detailed information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan and to calculate the effects of rotating velocity, flow rate, cut-off distance and the number of blades and its effects on the noise of the fan. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated with the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. The cut-off distance is the most important factor effecting the noise generation. Acoustic pressure is proportional to 2.8, which shows the same scaling index as the experimental result. In this paper, the cut-off distance is found to be the dominant parameter offecting the acoustic pressure.

• Journal of Korean Medicine Rehabilitation
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• v.24 no.3
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• pp.87-98
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• 2014

Objectives The present study aimed to investigate the effects of acupuncture and herbal external preparation on wound healing procedure in a deep partial thickness burn model in rats. Methods A total of 40 male Sprague-Dawley rats were allocated into four groups with an equal number in each group: acupuncture treatment group, herbal external perparation group, Silver sulfadiazine dressing group and control group. We describe the effect of acupuncture and herbal external preparation on morphologic and histologic changes, epithelial growth factor (EGF), hematological value of the deep partial thickness burn wound in rats. Results At 21th day after wounding the wound size in acupuncture treat group and herbal external preparation group were decreased more significantly compared to control group. In addition, epidermal regeneration on acupuncture treatment was than other treatment and control group in histological finding. Hematological findings revealed that acupuncture treatment group and herbal external prepartion group was more effective than control group in reducing inflammation response induced by burn. In acupuncture treated group, neutrophil and leukocyte level were significantly decreased compared to other treatment group. Also, this study showed that EGF was obviously expressed in nascent tissue when wounds were treated with the acupuncture and herbal external preparation after injury. In particular, acupuncture treatment group had a significant increase of EGF expression in burn wound healing area when compared with the other treatment groups. Conclusions These findings suggest that acupuncture and herbal external prepration may improve burn wound healing through decreasing inflammatory reaction, increasing tissue regeneration and expression of EGF. Moreover, acupuncture treatment could be more effective in comparison with Silver sulfadiazine dressing.

• Journal of Radiation Protection and Research
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• v.16 no.1
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• pp.43-52
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• 1991

A comparison study is performed on dose assessment programs including DOSE, LIMCAL, and PABLM, DOSE is a program developed for preliminary safety assessments of the low- and intermediate- level radioactive waste disposal, and the others are existing programs applicable to similar calculations. The results show acceptable agreement within an order of magnitude(mrem/yr) except for C-14 and Pu-239. PABLM results higher dose for C-14 while lower value for Pu-239 in comparison with those from DOSE or LIMCAL. It is found that the discrepancy in C-14 is due to difference in transport model introduced and that in Pu-239 is from the different value of dose conversion factor to each program.

• The Korean Journal of Air & Space Law and Policy
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• v.12
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• pp.210-245
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• 2000

This study is to review the problem concerned with aviation safety in Korea and suggest the solution to secure the aviation safety, in respect of regulation. At first, the definition and characteristics of aviation safety are studied, and then the endeavor for the aviation safety of ICAO and FAA are reviewed. All the fields of aviation safety area are included in the scope of this study; airworthiness in aircraft production and maintenance, flight operation, airport operation and air traffic control. The level of safety can be estimated by the frequency of accidents and seriousness. The causes of air accidents can be summarized as five factors; human factor, traffic environment. aircraft, weather, and unexpected incident. The activities to protect accidents are also can be summarized as five areas; man, machine, medium, mission and management. ICAO established the standards and recommends for the aviation safety, and adopted strategic action plan for 21st century. Federal Aviation Administration of USA also contributes for the aviation safety of world wide. Nowadays, ICAO and FAA tries to coordinate each other to set up efficient and effective ways for the aviation safety. ICAO developed safety oversight manual and FAA developed model regulations, individually. However, there has been trials to merge the results of each institute's studies. The direction of this endeavor is to meet the new environment related to globalization of air transport industry. It is necessary for our government to improve the aviation safety regulation system to address the new wave of aviation safety system pursued by international organization. A systematic and comprehensive measure should be devised by cooperation of all the related field and area.

• Survey Research
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• v.13 no.1
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• pp.89-112
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• 2012

This study aims to explore emotional closeness between grandparents and grandchildren in Korean families with a focus on the lineage. The effects of the geographical proximity and the normative aspect as well as intergenerational financial, instrumental, and emotional supports were taken into consideration to accounting for the grandparent-grandchildren affective solidarity. Research questions are addressed using the data of "Survey on Generational Solidarity and Differences in Cultural Experience and Perception in Korea", and a series of multinomial regression model were conducted. Findings indicate that the salient factor to boost grandchildren's affective solidarity with paternal grandparents is financial transfers between grandparents and parents. By contrast, all types of intergenerational supports affected grandchildren's emotional closeness toward maternal grandparents. Geographical proximity was associated with the affective solidarity between grandchildren and maternal grandparents. The effects of normative solidarity were not shown at both lineages.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.67-71
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• 2017

Debris disks are circumstellar dust disks around main-sequence stars. They are important observational clues to understanding the planetary system formation. The zodiacal light is the thermal emission from the dust disk in our Solar system. For a comprehensive understanding of the nature and the evolution of dust disks around main-sequence stars, we try a comparative study of debris disks and the zodiacal light. We search for debris disks using the AKARI mid-infrared all-sky point source catalog. By applying accurate flux estimate of the photospheric emission based on the follow-up near-infrared observations with IRSF, we have improved the detection rate of debris disks. For a detailed study of the structure and grain properties in the zodiacal dust cloud, as an example of dust disks around main-sequence stars, we analyze the AKARI mid-infrared all-sky diffuse maps. As a result of the debris disks search, we found old (>1 Gyr) debris disks which have large excess emission compared to their age, which cannot be explained simply by the conventional steady-state evolution model. From the zodiacal light analysis, we find the possibility that the dust grains trapped in the Earth's resonance orbits have increased by a factor of ~3 in the past ~20 years. Combining these results, we discuss the non-steady processes in debris disks and the zodiacal light.

• Journal of the Korean Electrochemical Society
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• v.8 no.4
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• pp.181-185
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• 2005

Lithium cobalt oxide thin film cathode, having thickness of $2.9{\mu}m$ with area of $4cm^2$, was deposited on platinum patterned alumina substrate by radio frequency magnetron sputtering. Li/Co molar ratio, which is an important factor for battery performance, was measured as a function of argon working pressure and applied R.F. power. Constant current charge and discharge performances were characterized with high rate discharge and cycling behavior. Using AC impedance analysis, internal resistance of the thin film battery was measured and simulated by proposed equivalent circuit model.

• Journal of the Economic Geographical Society of Korea
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• v.19 no.3
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• pp.457-473
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• 2016

This research investigates that role of space-based social capital presented in Dapsimni auto-parts shopping area considering Korean auto-parts industry and the regional characteristics of retailing industrial cluster. For this, it went through the process with in-depth interview and surveys of the owner of Dapsimni, social capital of retailing industrial cluster studied using Lin(1999)'s social capital model by separating formation, accessibility and mobilization of it. The result is that auto-part sellers in Dapsimni make themselves space-based social capital, which provides the profit from certain area: strengthening auto-parts of transaction cost and information exchange among them, creating new market for selling auto-parts. This meant that main factor sustaining the characteristic of retailing industrial cluster despite gradually decline of its role.

• Journal of Environmental Policy
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• v.12 no.4
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• pp.45-69
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• 2013

This study estimates baseline greenhouse gas emissions from transport sector when a new town is developed. It has adopted a general greenhouse gas estimation model developed by Schipper, celine, Roger(2000) for the estimation, and showed how various transport related statistics can be utilized in detail. Particularly, it has produced unit greenhouse gas emission factor per vehicle types, vehicle-km, and trip-km. To evaluate effects of greenhouse gas reduction policies, it has calculated how much emissions will be reduced from bicycle promotion. It has turned out that about 369 thousand tons of carbon dioxide will be emitted from transport sector once the 1st Geomdan New Town is developed in Incheon metropolitan city. If the policy of bicycle promotion can attract people to use bicycle as much as 5% of total trips, then it can reduce about 1,869 tons of carbon dioxide.

• Culinary science and hospitality research
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• v.15 no.2
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• pp.219-230
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• 2009

The purpose of this research was to investigate the success factors of the foodservice franchise business. This study examined relevant literatures, set up some hypotheses to solve main questionable consideration and made a corresponding empirical analysis. For the empirical analysis, a questionnaire survey was applied to ttotal 120 franchisers who have operated franchise business around Seoul. The result from the multiple regression model shows that the success of the franchise business is influenced by the operating system, the brand system, the educational system, and the franchisees' activities. As mentioned in the literature review and empirical analysis, it is found that the above mentioned four systems are equally affected by franchisers' success factors. The limits of this study include the fact that it has selected and researched around Seoul and four factors. Future research should be done from the perspective of such factors as culture, economy, region, menu, service and so on.