• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.252.2-252.2
• /
• 2013

ZnO nanostructures have a lot of interest for decades due to its varied applications such as light-emitting devices, power generators, solar cells, and sensing devices etc. To get the high performance of these devices, the factors of nanostructure geometry, spacing, and alignment are important. So, Patterning of vertically- aligned ZnO nanowires are currently attractive. However, many of ZnO nanowire or nanorod fabrication methods are needs high temperature, such vapor phase transport process, metal-organic chemical vapor deposition (MOCVD), metal-organic vapor phase epitaxy, thermal evaporation, pulse laser deposition and thermal chemical vapor deposition. While hydrothermal process has great advantages-low temperature (less than $100^{\circ}C$), simple steps, short time consuming, without catalyst, and relatively ease to control than as mentioned various methods. In this work, we investigate the dependence of ZnO nanowire alignment and morphology on si substrate using of nanosphere template with various precursor concentration and components via hydrothermal process. The brief experimental scheme is as follow. First synthesized ZnO seed solution was spun coated on to cleaned Si substrate, and then annealed $350^{\circ}C$ for 1h in the furnace. Second, 200nm sized close-packed nanospheres were formed on the seed layer-coated substrate by using of gas-liquid-solid interfacial self-assembly method and drying in vaccum desicator for about a day to enhance the adhesion between seed layer and nanospheres. After that, zinc oxide nanowires were synthesized using a low temperature hydrothermal method based on alkali solution. The specimens were immersed upside down in the autoclave bath to prevent some precipitates which formed and covered on the surface. The hydrothermal conditions such as growth temperature, growth time, solution concentration, and additives are variously performed to optimize the morphologies of nanowire. To characterize the crystal structure of seed layer and nanowires, morphology, and optical properties, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and photoluminescence (PL) studies were investigated.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.2
• /
• pp.336-344
• /
• 2002

In this study, the flow and combustion characteristics of flat flame burner with twirler were investigated. There are several factors that define the characteristics of burner. Among them, the experiments was focused on swirl effect by four types of twirler in terms of flow structure, distribution of temperature and emission characteristics. In PIV(Particle Image Velocimetry) experiment, the less of swirl number, axial flow is dominant at the center. As swirl number increases, the flow develops along the burner tile and backward flow becomes stronger at center. From the combustion characteristics, as long as combustion load increases, blow-off limit was improved. But at the higher swirl number, the limit is decreased. At swirl number 0, the temperature is shown typical distribution of long flame burner. but swirl number increases, the temperature distribution is uniform in front of round tile. Therefore, the temperature distribution is coincided with flow structure. As excess air ratio increases, NO concentrations are high. But high swirl number gives rise to become low NO concentrations. The flame characteristics are comprised in wrinkled laminar-flame regime according to turbulence Reynolds number(Rel) and Damkohler number(Da).

• Journal of Korea Society of Industrial Information Systems
• /
• v.25 no.2
• /
• pp.115-127
• /
• 2020

In this paper, a sustainable close-loop supply chain (SCLSC) model is proposed for effectively managing the production, distribution and handling process of mobile phone. The proposed SCLSC model aims at maximizing total profit as economic factor, minimizing total CO₂ emission amount as environmental factor, and maximizing social influence as social factor in order to reinforce sustainability in it. Since these three factors are represented as each objective function in modeling, the proposed SCLSC model can be taken into consideration as a multi-objective optimization problem and solved using a hybrid genetic algorithm (HGA) approach. In numerical experiment, three different scales of the SCLSC model are presented and the efficiency of the HGA approach is proved using various measures of performance.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.229-229
• /
• 2015

Downscaling is a fundamental procedure in the assessment of the future climate change impact at regional and watershed scales. Hence, it is important to investigate the spatial variability of the climate conditions that are constructed by various downscaling methods in order to assess whether each method can model the climate conditions at various spatial scales properly. This study introduces a fundamental research from Jang and Kavvas(2015) that precipitation variability from a popular statistical downscaling method (BCSD) and a dynamical downscaling method (MM5) that is based on the NCAR/NCEP reanalysis data for a historical period and on the CCSM3 GCM A1B emission scenario simulations for a projection period, is investigated by means of some spatial characteristics: a) the normalized standard deviation (NSD), and b) the precipitation change over Northern California region. From the results of this study it is found that the BCSD method has limitations in projecting future precipitation values since the BCSD-projected precipitation, being based on the interpolated change factors from GCM projected precipitation, does not consider the interactions between GCM outputs and local geomorphological characteristics such as orographic effects and land use/cover patterns. As such, it is not clear whether the popular BCSD method is suitable for the assessment of the impact of future climate change at regional, watershed and local scales as the future climate will evolve in time and space as a nonlinear system with land-atmosphere feedbacks. However, it is noted that in this study only the BCSD procedure for the statistical downscaling method has been investigated, and the results by other statistical downscaling methods might be different.

• Nuclear Engineering and Technology
• /
• v.51 no.5
• /
• pp.1444-1450
• /
• 2019

The fast-neutron shielding behaviour (FNSB) of two clay-materials (Ball clay and Kaolin)of Southwestern Nigeria ($7.49^{\circ}N$, $4.55^{\circ}E$) have been investigated using effective removal cross section, ${\Sigma}_R(cm^{-1})$, mass removal cross section, ${\Sigma}_{R/{\rho}}(cm^2g^{-1})$ and Mean free path, ${\lambda}$ (cm). These parameters decide neutron shielding behaviour of any material. A computer program - WinNC-Toolkit has been used for computation of these parameters. The toolkit evaluates these parameters by using elemental compositions and densities of samples. The proficiency of WinNC-Toolkit code was probe by using MCNPX and GEANT4 to model fast neutron transmission of the samples under narrow beam geometry, intending to represent the actual experimental setup. Direct calculation of effective removal cross section ($cm^{-1}$) of the samples was also carried out. The results from each of the methods for each types of the studied clay-materials (Ball clay and Kaolin) shows similar trend. The trend might be the fingerprint of water content retained in each of the samples being baked at different temperature. The compositions of each sample have been obtained by Particle-Induced X-ray Emission (PIXE) technique (Tandem Pelletron Accelerator: 1.7 MV, Model 5SDH). The FNSB of the selected clay-materials have been compared with standard concrete. The cognizance of various factors such as availability, thermo-chemical stability and water retaining ability by the clay-samples can be analyzed for efficacy of the material for their FNSB.

• Journal of Climate Change Research
• /
• v.7 no.4
• /
• pp.397-405
• /
• 2016

For better understand of the soil respiration characteristic in ecosystem, it is necessary to accurately determine the daily, monthly and seasonal $CO_2$ flux related to various environmental factors. In general, soil respiration is being measured on a sunny day. But soil respiration is known to be affected by soil temperature and soil moisture content. In case of forestry, changes in soil moisture content are entirely dependent on rainfall. If we calculated the monthly soil respiration measured based on sunny days data only, it could be a factor that loses credibility soil respiration. On this study, we measured soil respiration on Pinus koraiensis plantation at Mt. Taehwa of Gwangju, Gyeonggi-do on sunny and rainy days in 2012, using Automatic Open-Closed Chamber system (AOCC) and portable $CO_2$ analyzer (GMP343). Then we computed the regression equations using sunny days data, precipitation less than 10 mm data, and precipitation over 10 mm data. At first, there were no significant differences in observed data and computed data. But less than 10 mm precipitation, computed data was 26.5% lower than observed data. Precipitation over 10 mm, on the other hand, the former was 29.3% higher than the latter. In each case, it showed significant differences between observed and computed data (p<0.05). So if we computed regression equation using soil respiration measured sunny days only, about 30% of annual soil respiration could be overestimated. Through further study, we suggest the subdivision and computation of regression equation on the basis of the rainfall intensity.

• Advances in materials Research
• /
• v.8 no.1
• /
• pp.47-73
• /
• 2019

Joining of Mg/Ti hybrid structures by welding for automotive and aerospace applications has attracted great attention in recent years due mainly to its potential benefit of energy saving and emission reduction. However, joining them has been hampered with many difficulties due to their physical and metallurgical incompatibilities. Different joining processes have been employed to join Mg/Ti, and in most cases in order to get a metallurgical bonding between them was the use of an intermediate element at the interface or mutual diffusion of alloying elements from the base materials. The formation of a reaction product (in the form of solid solution or intermetallic compound) along the interface between the Mg and Ti is responsible for formation of a metallurgical bond. However, the interfacial bonding achieved and the joints performance depend significantly on the newly formed reaction product(s). Thus, a thorough understanding of the interaction between the selected intermediate elements with the base metals along with the influence of the associated welding parameters are essential. This review is timely as it presents on the current paradigm and progress in welding and joining of Mg/Ti alloys. The factors governing the welding of several important techniques are deliberated along with their joining mechanisms. Some opportunities to improve the welding of Mg/Ti for different welding techniques are also identified.

• Convergence Security Journal
• /
• v.18 no.3
• /
• pp.45-51
• /
• 2018

Recently, Crypto currency has evolved along with Blockchain technology and the voice of concern and concern of many people. Global nations that consider the use of Crypto currency are prudent in their protection of their economies due to legal regulations and institutional arrangements, and are watching the trends of various Crypto currency. Among them, Crypto currency is very popular because it can acquire money through cryptographic computation. However, there is a need to consider the impact of high-quality computing resources and the consumption of many electrical energy on global warming. Therefore, this study investigated the calculation of electric energy consumption and Carbon Dioxide Emissions, data and cases related to the mining of Crypto currency, examined variable factors. This will be used as research data that will respond to the 4th industrial revolution, such as the presentation of a more positive development direction of Crypto currency, and the development of various related technologies.

• BLOOD RESEARCH
• /
• v.53 no.4
• /
• pp.281-287
• /
• 2018

Background Bone marrow involvement (BMI) affects the lymphoma stage, survival, and treatment. Bone marrow biopsy (BMB) and fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) are useful techniques to detect BMI. Both have advantages and disadvantages. We aimed to identify factors that could be used to predict BMI with positive and negative results on PET/CT compare them with BMB in newly diagnosed patients with lymphoma. Methods We included 22 non-Hodgkin and 16 Hodgkin lymphoma patients in this single center study. All patients had PET/CT examination and BMB before treatment. BMI in BMB was reported as negative or positive. Bone marrow was classified into 3 types by FDG uptake on PT/CT; diffuse involvement, focal involvement, and normal bone marrow. Results PET/CT and BMB results were concordant (7 positive, 15 negative) in 22 patients (57%). We evaluated concordant and discordant patient characteristics and risk-stratified patients for BMI. Our findings suggest that patients with diffuse FDG uptake on PET/CT, especially patients with advanced age and low platelet and white blood cell counts, are likely to have BMI and could potentially forego BMB. Patients with negative PET/CT findings and no significant laboratory abnormalities are very unlikely to have BMI. Conclusion Our results suggest that BMI should not be decided solely based PET/CT or BMB findings. It is reasonable to use both diagnostic assays along with clinical and laboratory findings. PET/CT result, clinical and laboratory findings could be useful for predicting BMI in patient for whom BMB is contraindicated.

• Asia-Pacific Journal of Business
• /
• v.11 no.3
• /
• pp.169-184
• /
• 2020

Purpose - This research is intended to analyze the current status and problems of tax benefits in the R&D sector and suggest ways to improve tax credit for research and manpower development expenses when various countries fiercely develop efforts to enhance national competitiveness through increased investment in R&D Design/methodology/approach - This study will examine the current status of the tax support system for domestic and foreign R&D, and suggest improvement measures to expand research and development activities in the future. Findings - First, a plan may be considered to abolish and perpetuate the sunset deadline for tax credit for research and manpower development expenses as in the case of the United States and Japan. This perpetuation can be a proactive measure to actively support long-term R & D investment in companies facing economic decisions under uncertainty. Second, it should be revised to raise the tax credit rate of large corporations, which are shrinking every year, compared to SMEs, so that both large corporations and SMEs can improve their international competitiveness and secure excellent technologies through R & D. Finally, the target technologies for each new growth engine and source technology should be expanded to various fields, including national cybersecurity enhancement technology, aviation engine technology, carbon emission and global cooling technologies, which are areas of interest in major overseas R&D countries, to help active R&D and investment in these areas. Research implications or Originality - This study can find a contribution in comparing and analyzing the national R&D tax support system and presenting improvement measures at a time when the benefits of tax credit for research and manpower development expenses of large companies are decreasing due to frequent tax law revisions and the government's factors of increasing tax revenues. In addition, recent research and development items and research technologies of foreign countries were analyzed by Nature's top 10 major science and technology issues, and advanced technologies that should be applied to target technology areas by new growth engine and source technology were specifically investigated and presented.