• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.297-301
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• 2008

The flight vehicles have cavities such as wheel wells and bomb bays. The flow around a cavity is characterized as unsteady flow because of the formation and dissipation of vortices due to the interaction between the freestream shear layer and cavity internal flow, the generation of shock and expansion waves. Resonance phenomena can damage the structures around the cavity and negatively affect aerodynamic performance and stability. The flow field is observed to oscillate in the "shear layer mode" with low aspect ratio. In the present study, numerical analysis was performed for cavity flows by the unsteady compressible three dimensional Reynolds-Averaged Navier-Stokes (RANS) equations with Wilcox's $\kappa$-$\omega$ turbulence model. The flow field is observed to oscillate in the shear layer mode" with large aspect ratio. Based on the SPL(Sound Pressure Level) analysis of the pressure variation at the cavity trailing edge, the dominant frequency was analyzed and compared with the results of Rossiter's formul. The aero-acoustic wave analyzed with CPD(Correlation of Pressure Distribution).

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.297-301
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• 2008

The flight vehicles have cavities such as wheel wells and bomb bays. The flow around a cavity is characterized as unsteady flow because of the formation and dissipation of vortices due to the interaction between the freestream shear layer and cavity internal flow, the generation of shock and expansion waves. Resonance phenomena can damage the structures around the cavity and negatively affect aerodynamic performance and stability. The flow field is observed to oscillate in the "shear layer mode" with low aspect ratio. In the present study, numerical analysis was performed for cavity flows by the unsteady compressible three dimensional Reynolds-Averaged Navier-Stokes (RANS) equations with Wilcox's ${\kappa}-{\varepsilon}$ turbulence model. The flow field is observed to oscillate in the "shear layer mode" with large aspect ratio. Based on the SPL(Sound Pressure Level) analysis of the pressure variation at the cavity trailing edge, the dominant frequency was analyzed and compared with the results of Rossiter's formul. The aero-acoustic wave analyzed with CPD(Correlation of Pressure Distribution).

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.99-104
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• 2014

Purpose: This study was to investigate the functional improvement in peripheral vision following eccentric viewing training. Methods: 14 subjects with normal vision took a part with their right eye, peripheral retinal which is $20^{\circ}$ lateral area from the fovea was examined for contrast sensitivity(CS). Eccentric viewing training was performed for 21days with an hour image viewing and examination was repeated. Results: The critical durations for 0.7 cpd were increased 2.67(467 ms) for pre-eccentric viewing training to 2.79(616 ms) for post-eccentric viewing training (p>0.05). The critical durations for 3.0 cpd were also increased 2.53(341 ms) for pre-eccentric viewing training to 3.04(1102 ms) for post-eccentric viewing training (p>0.05). Conclusions: It is recommended to use higher spatial frequency with higher CS for eccentric viewing training and to train more frequently for a short time. Moreover, the study on Korean standardizing of the visual rehabilitation for low vision based on the etiology is sorely required.

• Journal of Energy Engineering
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• v.21 no.1
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• pp.68-74
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• 2012

Sub-bituminous coals have been used increasingly in coal-fired power plants with a proportion of over 50% in the blend with bituminous coals. As a result, the unburned material in fly ash has increased and is causing problems in utilizing the fly ash as an additive for concrete production. In this study, analysis of fly ash obtained from a 500 MWe power plant was carried out and unburned material in the fly ash found to be soot. The coals used in the plant were analyzed with CPD model to investigate the sooting potential depending on the coal type and blending ratio.

• Korean Journal of Poultry Science
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• v.37 no.1
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• pp.81-87
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• 2010

To estimate the genetic characteristics and cumulative power of discrimination (CPD) Korean Native Chicken. We used a total of 195 genomic DNAs from four breeds population (Korean Native Red chicken: R, Korean Native Yellow chicken: Y, Korean Native Black chicken: L, Ogal chicken: S). Frequencies of microsatellites markers were used to estimate heterozygosities and genetic distances. The lowest distance (0.05) was observed between the R and L strains and the highest distance (0.158) between the L and S strains. Korean native chicken strains (R, Y, K) have each other comparatively near genetic distance. Cumulative power of discriminate (CPD) was 99.999% by including the 10 microsatellites loci individual identification system. And then matching probability in that two different individuals incidentally have same genotype was estimated to $0.36{\times}10^{-7}$. The system employing the 10 markers therefore provided to be applicable to individual identification in Korea native chicken.

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.13-18
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• 2009

Flight vehicles such as wheel wells and bomb bays have many cavities. The flow around a cavity is characterized as an unsteady flow because of the formation and dissipation of vortices brought about by the interaction between the free stream shear layer and the internal flow of the cavity. The resonance phenomena can damage the structures around the cavity and negatively affect the aerodynamic performance and stability of the vehicle. In this study, a numerical analysis was performed for the cavity flows using the unsteady compressible three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equation with Wilcox's turbulence model. The Message Passing Interface (MPI) parallelized code was used for the calculations by PC-cluster. The cavity has aspect ratios (L/D) of 2.5 ~ 7.5 with width ratios (W/D) of 2 ~ 4. The Mach and Reynolds numbers are 0.4 ~ 0.6 and $1.6{\times}106$, respectively. The occurrence of oscillation is observed in the "shear layer and transient mode" with a feedback mechanism. Based on the Sound Pressure Level (SPL) analysis of the pressure variation at the cavity trailing edge, the dominant frequencies are analyzed and compared with the results of Rossiter's formula. The dominant frequencies are very similar to the result of Rossiter's formula and other experimental data in the low aspect ratio cavity (L/D = ~ 4.5). In the large aspect ratio cavity, however, there are other low dominant frequencies due to the leading edge shear layer with the dominant frequencies of the feedback mechanism. The characteristics of the acoustic wave propagation are analyzed using the Correlation of Pressure Distribution (CPD).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1246-1254
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• 2012

The South Korea has the highest overall smoking rates of male among the thirty member-countries in the Organization for Economic Cooperation and Development. This study was performed to determine the association between amount of smoking and self-reported voice problem in Korean adult population using national survey data. Data were drawn from the Korea National Health and Nutritional Examination Survey 2008. Subjects were 3,600 persons (1,501 male, 2,099 female) aged 19 years and older living in the community. Adjusting for covariates (age, sex, education, income, longest occupation, alcohol drinking, pain and discomfort during the last 2 weeks), Severe smoke (>40.5-55.5 pack year), more than 20 cigarettes per day were independent risk factors for self-reported voice problem. It was found that the number of cigarettes smoked per day (CPD) the proportional increased in risk of voice disorders. These findings suggest that the investigation of CPD are required for effective screening of voice disorder.

• Childhood Kidney Diseases
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• v.12 no.2
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• pp.202-212
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• 2008

Purpose : The aim of this study was to develop a quality of life scale for children on chronic peritoneal dialysis(QOL-CPD). Methods : Thirty children on chronic PD at Seoul National University Children's Hospital participated. A healthy control group included 47 elementary school children. Other patients groups are 32 children from the department of pediatric orthopedics and 28 children from the department of child psychiatry. The age range of all children was 7 to 16 years. Preliminary items of the QOL-CPD were developed and administered along with the Korean version of the Children's Depression Inventory(CDI) to all children. Results : The final QOL-CPD was constructed by excluding those items with a factor loading of less than .20, and the principal axis factor analysis was performed again. The QOLCPD demonstrated a good internal consistency with a value of .87. The dialysis and childpsychiatric groups showed significantly lower QOL scores compared to the healthy control group. In addition, the dialysis and child-psychiatric groups showed greater difficulties on physical and academic functions. For the CDI, the PD group showed a mild level of depression. Conclusion : The results of this study demonstrate the clinical utility of a newly developed self-report QOL scale specific for children on chronic PD.

• Journal of Digital Convergence
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• v.14 no.9
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• pp.453-459
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• 2016

The 'Collaboration Marketing' is at its prime in domestic-cosmetic market. It is one of the most well known strategic marketing methodologies that maximize customers' attention by combining visual images or illustrations with market's current best selling products. The ultimate goal of my study relies on analyzing the correlation between 'Collaboration Package-Design (CPD)' and customer's actual purchase. Literature research was conducted as the primary step for theoretical basis, while the secondary step mainly deals with three different types of existing 'collaboration marketing' in the worldwide cosmetic market. Lastly, an empirical study through hypothesis test, survey and in-depth interview was conducted. As the outcome of study, two among three hypothesis have been proven while 'Character collaboration' which based on the concept of 'Kidult' (combined concept of Kid and adult) is the most popular tool. This study supports the idea that consumers get more influences from 'image and scarcity' of CPD rather than the actual function or performance of cosmetic products.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.10
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• pp.1065-1073
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• 2006

The unturned carbon in fly ash, recently occurred in the coal-fired Yong Hung power station, caused some problems in ash utilization and boiler efficiency. This paper describes the analysis of unburned carbon and six coals, some tests performed at Yong Hung Boiler, and the results of combustion modification for the reduction of unburned carbon in fly ash. From the physical and chemical analysis of unburned carbon in fly ash, most particles were turned out to be hollow cenosphere and agglomerated soot particles. The sooting potential from six coals used in the plant were investigated with CPD(Chemical Percolation Devolatilization) model. The results showed that the higher potential was presented to Peabody, Arthur, Shenhua coals rather than other coals. It was necessary to measure the coal flow rates at each coal feeding pipe for four burner levels since they affect the extent of mixing of soot with oxidant, in turn, the oxidation rate of soot particles. The unbalance in coal flow rate was found in several coal pipes. We successfully reduced unturned carbon in ash by increasing the excess air and changing the SOFA's yaw angle.