• Journal of Information Display
• /
• v.2 no.3
• /
• pp.78-85
• /
• 2001

The growth of carbon nanotubes(CNTs) in anodic aluminum oxide(AAO) template and their application to a field emitter are described. AAO templates were fabricated by anodizing bulk aluminum and sputtered thin Al film on Nb-coated Si wafers. After Co catalyst had been electrochemically deposited into the bottom of the pores in AAO template, CNTs were grown by pyrolyzing $C_2H_2$. Depending on the reaction conditions, CNTs grew up to or over the top of the pores in AAO template with different structures. The morphology and structure of CNTs were observed with a scanning electron microscope and a transmission electron microscope. The diameter of CNTs strongly depended on the size of the pores in AAO template and the growing conditions. The electron field emission measurement of the samples resulted in the turn-on field of 1.9-2.2 $V/{\mu}m$ and the field enhancement factor of 2450-5200. The observation of high field enhancement factors is explained in terms of low field screening effect.

• Journal of computational fluids engineering
• /
• v.15 no.2
• /
• pp.86-94
• /
• 2010

A thermal-hydraulic code, named CUPID, has been developed for the analysis of transient two-phase flows in nuclear reactor components. A two-fluid three-field model was used for steam-water two-phase flows. To obtain numerical solutions, the finite volume method was applied over unstructured cell-centered meshes. In steam-water two-phase flows, a phase change, i.e., evaporation or condensation, results in a great change in the flow field because of substantial density difference between liquid and vapor phases. Thus, two-phase flows are very sensitive to the local pressure distribution that determines the phase change. This in turn puts emphasis on the accurate evaluation of local pressure gradient. This paper presents a new reconstruction method to evaluate the pressure gradient at cell centers on unstructured meshes. The results of the new scheme for a simple test function, a gravity-driven cavity, and a wall boiling two-phase flow are compared with those of the previous schemes in the CUPID code.

• Journal of Ecology and Environment
• /
• v.37 no.3
• /
• pp.123-129
• /
• 2014

Ant communities are well suited for monitoring changes in ecosystems. Although numerous studies have examined the responses of ant communities to environmental disturbance, relatively few long-term studies on ant communities have been undertaken in urban environments. We examined species richness in nine urban parks in Hiroshima, Japan, and compared the survey results with data collected at the same sites by using the same methods in 1999. In both surveys, total of 25 species was recorded: 23 species in 1999 and 20 species in 2012. Non-metric multidimensional scaling analysis revealed that the ant communities consisted of two distinct groups, which could in turn be characterized by three patterns of ant community changes in between the two groups. The first of these community change patterns was characterized by a shift within group 1, but the number of species remained constant (approx. 10 species). The second pattern was characterized by a shift within group 2, but the number of species remained low (approx. 4 species). The third pattern was characterized by a shift from group 1 to group 2 as the abundance of Linepithema humile (Mayr) increased over time. Unlike the first and second patterns, the number of ant species in communities of the third type decreased significantly. These findings suggest that L. humile has a marked effect on the species diversity of indigenous ant communities in urban environments.

• Journal of Information Technology Services
• /
• v.14 no.1
• /
• pp.1-21
• /
• 2015

Recently, many companies have launched a new business model related to the mobile gift service in order to achieve or sustain a competitive advantage in the fast-growing mobile market. Due to the well combination of mobile technology advantages and offline gift-giving motivations, a mobile gift service has been proliferating over recent years. Although the motivation of mobile gift purchasing behavior can be different from that of offline gift purchasing behavior, there is still a lack of research on what factors are influencing and how they are impacting mobile gift purchasing behavior under diverse gift-giving settings. Therefore, based on both exchange and motivation theories as well as literature review, this study identified three influencing factors-economic (immediate rewards, convenience), social (friendship needs, reputation), and personal (enjoyment, self-satisfaction) benefits-and validated their impacts on intention to repurchase a mobile gift. Moreover, the moderating roles of intimacy and gift price in the relationships between benefits and mobile gift repurchasing intention were examined. The results provide many implications for marketing managers on how to enhance consumers' intention to repurchase, which in turn leads to sales and increased profit.

• Atmosphere
• /
• v.19 no.1
• /
• pp.67-78
• /
• 2009

A strong negative correlation has been detected between the North Pacific Oscillation Index (NPI) and the Effective Drought Index (EDI) in May over Korea. In May of positive NPI year, anomalous patterns caused a drought in Korea as follows: the anomalous south-low, north-high low-level pressure patterns in the northeast and southeast of Korea have strengthened the anomalous northerlies to Korea. In addition, these anomalous northerlies have prevented western North Pacific (WNP) high from moving northward. As a result, anomalous descending flows have strengthened in the mid-latitude region in East Asia. In the WNP, the anomalous south-high, north-low sea surface temperature (SST) has been widely distributed, which has strengthened anomalous south-low, north-high low-level pressure patterns. These anomalous characteristics of pressure and SST patterns observed in May of positive NPI years have already been detected in previous winter (December-February) and early spring (March, April). In addition, the anomalous negative sea ice concentration in the North Pacific during two seasons has strengthened the anomalous anticyclonic circulation in the same region and in turn made a contribution to formation of anomalous south-low, north-high pressure patterns in May.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.11a
• /
• pp.65-65
• /
• 2009

High temperature silicon carbide Schottky diode was fabricated with Au deposited on poly 3C-SiC thin film grown on p-type Si(100) using atmospheric pressure chemical vapor deposition. The charge transport mechanism of the diode was studied in the temperature range of 300 K to 550 K. The forward and reverse bias currents of the diode increase strongly with temperature and diode shows a non-ideal behavior due to the series resistance and the interface states associated with 3C-SiC. The charge transport mechanism is a temperature activated process, in which, the electrons passes over of the low barriers and in turn, diode has a large ideality factor. The charge transport mechanism of the diode was analyzed by a Gaussian distribution of the Schottky barrier heights due to the Schottky barrier inhomogeneities at the metal-semiconductor interface and the mean barrier height and zero-bias standard deviation values for the diode was found to be 1.82 eV and $s_0$=0.233 V, respectively. The interface state density of the diode was determined using conductance-frequency and it was of order of $9.18{\times}10^{10}eV^{-1}cm^{-2}$.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.531-536
• /
• 2003

In this paper, a redesigned guidance and control system for a lunar lander is presented. In past studies, the authors developed a trajectory and attitude control system which achieves the vertical soft landing on the lunar surface. It is confirmed that the system has a good tracking ability to a predefined profile and good robustness against a thruster failure mode where a partial failure of clustered engines was assumed. However, under the previous control laws, the landing point tends to be shifted, in response to the system parameter values, from a target point. Also, an unbalanced moment due to a thruster failure mode was not considered in the simulation. Therefore, in this study, the downrange control is added to the system to enable the vehicle to land at a pre-assigned target point accurately. Furthermore, inhibiting the effect of the unbalanced moment is attempted thorough redesigning the attitude control system. A numerical simulation was performed to confirm the ability of the proposed system with regard to the above problems. Moreover, in the past simulations, a low initial altitude was assumed as an initial condition: in this study, however, the performance of the proposed system is examined over the whole trajectory from an initial altitude of 10 [km] to the lunar surface.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.9
• /
• pp.3693-3711
• /
• 2020

e-Governance is a medium to offer various services to citizens through a web portal, that exists in many countries nowadays. The existing e-Governance technology is a vast, centrally managed database and a set of applications that connect to it via web interfaces. Despite the modernisation of services, it remains with the lack of transparency. Thus, the existing infrastructure of e-Governance paves the way for corrupt practises by the bureaucrats. e-Governance needs a powerful underlying technology which doesn't provide any way to allow tampering of the record and which in turn eliminates corruption. In this paper, we took land registration as a use-case for building e-Governance by keeping Blockchain as an underlying technology, to put off the corrupt practices and to bring transparency. Once transactions in land registration added to the Blockchain, it is immutable as it is cryptographically secured. Besides, the blockchain technology is secured as the ledger is distributed over the network. If a hacker wants to modify the ledger, he needs to hack every node in the blockchain network. Hyperledger Fabric, a permissioned Blockchain adopted for implementation and Hyperledger Caliper for performance analysis with these evaluation metrics such as throughput, latency and execution time.

• The Journal of Korean Academic Society of Nursing Education
• /
• v.22 no.3
• /
• pp.355-365
• /
• 2016

Purpose: This study explores the moral distress that nursing students experience during their clinical practice in Korea. Methods: Data were collected using focus group interviews, and analyzed using qualitative content analysis. Participants were recruited from three nursing schools in three different cities; each focus group interview lasted between one to two hours. Results: Twenty-two nursing students with more than one year of clinical practice experience participated. Three categories and ten themes were extracted. The following situational categories: "unprotected patients' right and dignity," "clinical settings in which standards of care are not upheld," "disrespectful hospital culture," and "inconsistent and unsystematic clinical education" caused moral distress. Types of responses to moral distress included: "shock and confusion over the gap between reality and moral standards," "powerlessness when cannot advocate patients," "fear and doubts about nursing career," and "moral desensitization and disappointment in oneself." "Expressions of moral distress and the need for advice" and "a search for meaning and hope" were identified as coping strategies. Conclusion: These results demonstrate the need for systematic clinical practicum and education programs to minimize moral distress. These programs may offer opportunities for students to turn moral distress into opportunities for learning and growth in the future.

• Journal of The Korean Society of Integrative Medicine
• /
• v.6 no.1
• /
• pp.99-105
• /
• 2018

Purpose : The purpose of this study was to evaluate the effect of craniocervical flexion exercise on deep cervical flexor thickness and gait in children with hemiplegic cerebral palsy. Methods : Twelve children with hemiplegic cerebral palsy were recruited for this study. All subjects performed active craniocervical flexion exercise 3times a week over the course of 6weeks. using a pressure bio feedback unit. Ultrasonography was used to assess deep cervical flexor thickness, and a 10m walking test was used to assess gait function. For the statistical analysis, a paired t-test was used to compare the differences pre- and post-value. SPSS Statistics version 20.0 was used for statistical analysis, and statistical significance was defined as a p-value less than 0.05. Result : The results of this study indicate that children with hemiplegic cerebral palsy experienced statistically significant positive changes in both deep cervical flexor thickness (p<.05). and gait(p<.05) following the intervention. Conclusion : In conclusion, craniocervical flexion exercise can positively affect deep cervical flexor thickness in children with hemiplegic cerebral palsy, which in turn positively affects gait.