• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.18 no.12
• /
• pp.1080-1086
• /
• 2005

We have studied the Ge redistribution after dry oxidation and the oxide growth rate of $Si_{1-x}Ge_x$ epitaxial layer. Oxidation were performed at 700, 800, 900, and $1,000\;^{\circ}C$. After the oxidation, the results of RBS (Rutherford Back Scattering) & AES(Auger Electron Spectroscopy) showed that Ge was completely rejected out of the oxide and pile up at $Si_{1-x}Ge_x$ interface. It is shown that the presence of Ge at the $Si_{1-x}Ge_x$ interface changes the dry oxidation rate. The dry oxidation rate was equal to that of pure Si regardless of Ge mole fraction at 700 and 800$^{\circ}C$, while it was decreased at both 900 and $1,000^{\circ}C$ as the Ge mole fraction was increased. The dry of idation rates were reduced for heavy Ge concentration, and large oxiidation time. In the parabolic growth region of $Si_{1-x}Ge_x$ oxidation, the parabolic rate constant are decreased due to the presence of Ge-rich layer. After the longer oxidation at the $1,000^{\circ}C$, AES showed that Ge peak distribution at the $Si_{1-x}Ge_x$ interface reduced by interdiffusion of silicon and germanium.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.1
• /
• pp.47-51
• /
• 2017

Recently international cooperations are formed to deal with the environmental pollution of the atmosphere generated by the vapor compression refrigeration system. A refrigeration technique, which can replace existing CFC refrigerants that are the main cause of environmental contamination, has received greater attention. Magnetic refrigeration is a refrigeration technique using the magnetocaloric effect of the magnetic material, and is an eco-friendly refrigeration technology using the solid refrigerant instead of CFC refrigerants. Also it is regarded as an efficient refrigeration system to generate temperature difference between high and low sides using the temperature change of magnetic refrigerants according to the change of magnetic field, instead of using power-consuming and noisy compressor. In this paper, we introduce the magnetic refrigeration apparatus using concentric Halbach cylinder permanent magnets and the experimental results using the apparatus.

• Ocean and Polar Research
• /
• v.37 no.2
• /
• pp.119-125
• /
• 2015

This paper focuses on the efficient arrangement plan of buoyancy modules, which plan is used to secure the safe operation and structural stability of a marine riser. The marine riser is connected between a vessel and seabed devices. The movement of the vessel and the seabed devices are affected by the motion of the riser. The riser of a deep-seabed integrated mining system exerts a strong influence on the healthy transfer of minerals. So, buoyancy modules must be equipped to compensate for the problem which is the structure stability and the dynamic motion. Installation locations and quantities of the buoyancy modules are determined by real sea experiments. But this is not easy to do because in real sea experimental conditions the cost is expensive as well as being, time-consuming and dangerous. Therefore, the locations and quantities should be determined by numerical simulation. This method is called simulation-based design. The dynamic analysis models of the riser and the buoyancy modules are built into the commercial software of DAFUL.

• Journal of the Korea Society of Computer and Information
• /
• v.11 no.2 s.40
• /
• pp.7-13
• /
• 2006

The advent of Semantic Web has generated several methods that can access the data on the web. Thus, it is necessary to handle the data by accessing the current web ontology as well as the existing knowledge base system. Web ontology languages are RDF(Resource Description Framework), DAML-OIL, OWL(Web Ontology Language), and so on. This paper presents the creation and the method of the ontology object model that can access, represent, and process the web ontology and the existing knowledge base. Unlike the existing access approach of web ontology using the model on memory constructed by each parser, we divide the model of web ontology into three layers such as frame-based ontology layer, generic ontology layer, and functional ontology layer. Generic ontology layer represents the common vocabulary among several domains and functional ontology layer contains the dependent vocabulary to each ontology respectively. Our model gets rid of the redundancy of the representation and enhances the reusability. Moreover, it can provide the easy representation of knowledge and the fast access of the model in the application.

• Journal of Satellite, Information and Communications
• /
• v.5 no.2
• /
• pp.8-13
• /
• 2010

Satellite structure should be designed to accommodate and support safely the payload and equipments necessary for its own missions and to secure satellite and payloads from severe launch environments. The launch environments imposed on satellites are quasi-static accelerations, aerodynamic loads, acoustic loads and shock loads. Especially when optical payload is accommodated, satellite structure usually adopts the optical bench consisting of composite material not only to support and secure but also to guarantee good pointing stability against extreme thermal environments. This paper deals with optical bench and support structure which shall be designed to minimize the loads transferred to optical payloads from satellite.

• Journal of Digital Convergence
• /
• v.15 no.2
• /
• pp.89-98
• /
• 2017

This study analyzed empirically the same data through SPSS statistics(regression analysis) and AMOS program(structural equation model) used for cause and effect analysis. The result of empirical analysis of moderation effect was as follows. Meanwhile, SPSS statistics(regression analysis) did not pictured moderation effect in the categorical data(sex) and continous data(satisfaction of consunting), AMOS program(structural equation model) pictured partial moderation effect about the effecting of consultant's capability and attitude on the consulting repurchase within 10% level of significant. Eventually, This study showed that AMOS program and SPSS statistics used different methology in moderation effect, thus the different outcomes appeared although using the same data.

• Korean Journal of Digital Imaging in Medicine
• /
• v.10 no.1
• /
• pp.5-6
• /
• 2008

In this study, using an experiment, in certified an error between each system of SUV (standardized uptake value) that is one of the main analyses to diagnose a tumor in PET/CT, so, it would assure reliability and help to diagnose any lesions accurately. That is, a detailed analysis progressed. as all images reconstructed every setting time, then, clinical reliability between each system was expressed numerically at MBq/mL and SUV. Therefore, this study is considered that flexibility of follow-up using diverse system was insured, and it helps to offer accurate and beneficial information for diagnosis of various fields.

• Tunnel and Underground Space
• /
• v.21 no.1
• /
• pp.1-10
• /
• 2011

In these days, the development of optical fiber sensor technology is so remarkable that it can measure various physical and chemical quantities ranging from a few millimeters to over several kilometers. In addition, it is attempted to assess the structural integrity of the state of the advanced technologies and existing structures such as ships, aircrafts, and bridges. This paper introduced the case histories of the measuring technology of optical fiber applied on structures such as roads and tunnels. The case history using OTDR (Optical Time Domain Reflectometery) was also introduced in this paper. Measurement of the pre-convergence of a tunnel is essential to assess the safety of a tunnel and understand the geological conditions ahead of an advancing tunnel. Therefore, the pre-convergence measuring technology using OTDR is expected to substitute conventional measuring techniques.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.4
• /
• pp.846-851
• /
• 2007

The wireless sensor network is one of the most practical and cost-effective solutions for monitoring systems covering wild and wide area such as wildfire monitoring. However, the RF distance between sensor nodes is very short due to the need of low power consumption of the sensor node, so the number of sensor nodes to be deployed in the target area is more than tens of thousands. In this paper, we design and analyze the deployment issues as well as re-deployment problem occurred when the battery is exhausted. We also propose the needs and solutions for coverage problem in dynamic deployment. By the experimental evaluations, we analyze the packet success ratio between sensor nodes under various environments such as obstacles and variable distances.

• Korean Journal of Social Welfare Studies
• /
• v.43 no.1
• /
• pp.305-337
• /
• 2012

The OECD High Level Forum-4 that was held in Busan in 2011 was a very important international conference in which more than 2,000 high level representatives from OECD countries, UN, private businesses, charity foundations, NGOs, etc participated, and which dealt with the aid effectiveness issues of ODA (Official Development Assistance), one of the important funds for social welfare of developing countries. However, despite its significance, none of social work organizations, either international or domestic, were in appearance during the conference. What made such a thing happen? This study started from that question and tried to explore the history of international social work: when and how social work gained an international leadership in caring for social welfare of developing countries and how and why it began to lose it. This study also tried to explore, based on the international experience, the tasks that Korean social work community, both academia and field, which just began to be concerned with international social work for developing countries, should address at this beginning stage.