• Applied Science and Convergence Technology
• /
• v.25 no.4
• /
• pp.73-76
• /
• 2016

Multi-layer films of $SiN_x/SiO_x$/InSnO with anti-reflective effect were grown by new-concept plasma enhanced chemical vapor deposition system (PECVD) with hybrid plasma source (HPS). Anti-reflective effect of $SiN_x/SiO_x$/InSnO was investigated as a function of ratio of $SiN_x$ and $SiO_x$ thickness. Multi-layers deposited by PECVD with HPS represents the enhancement of anti-reflective effect with high transmittance, comparing to the layers by conventional radio frequency (RF) sputtering system. This change is strongly related to the optical and physical properties of each layer, such as refractive index, composition, film density, and surface roughness depending on the deposition system.

• Journal of the Korean housing association
• /
• v.16 no.5
• /
• pp.75-81
• /
• 2005

The purpose of this study is to shed light on the field dynamics of 'lived space' in the light of our intuitive experiential contents by way of investigating three properties of space. While finding inspirations in the field theory of modern physics, investigation of our intuitive responses to the physical and spatial environment leads us to a coherent view of matter and space. We find then that our lived world is more than a system of inert matter; it is a dynamic environment of life in which feeling and mood, spiritual meaning and value, are perpetually infused with matter. Any concept of space, if it is to be meaningful to lift has to somehow acknowledge this fact. Empty space and matter cannot be conceived as mutually exclusive and independent as in classical physics. Rather they should be seen as two different manifestations of an underlying dynamism which permeates the world. The 'properties' of space can only be understood in terms of the 'impact' of material presence. The object cannot be seen as an isolated entity, but the 'conditioning' of its surrounding space has to be understood as an integral part of its being. Lived space can thus be viewed as an emotionally charged field, or a field of emotional energy, whose properties may be described in terms of concentration, mobility and resonance.

• Journal of Korean Elementary Science Education
• /
• v.23 no.3
• /
• pp.199-207
• /
• 2004

Elementary science curriculum is designed to be closely-related magnetism with electricity in a physics domain and this paper explored whether elementary school students have recognized of relationships between them and whether there are any trends in the degree of recognition by grades. The elementary students of 3rd to 6th grade (total 154 persons) in a school in a local city participated in the experiment. Two forms of questionnaire were administrated to each grades. In the first questionnaire about magnetism, students were asked to rank the physics terms as the degree of proximity into magnetism and to write briefly the reason. In the second questionnaire about electricity, students were asked to do the same routine. The closer to the central term in the diagram, the lower score were given and the terms were classified as closely related to magnetism, electricity and the rest. Calculated the response frequency and averaged by the ranked terms, it was examined that the scores of proximity in how students closely rated conception to magnetism and electricity. The result said that the upper grades students showed the degree of proximity with magnetism and electricity as closely. Therefore, the sequence of comprehension of magnetism and electricity concept, which was found in the elementary school curriculum, seems to be found in the elementary students＇ recognitions by grades.

• Progress in Medical Physics
• /
• v.19 no.2
• /
• pp.113-119
• /
• 2008

In this study, we have estimated error of calculation results for 5-type RTP systems and investigated a toleration for error of the RTPs referenced from the evaluation items of AAPM Report-62. For this study, we have introduced the concept of 'normal dose rate(NDR)' and compared the results of experiment and calculation from RTPs at the same reference level. The results from all RTPs were satisfied at various field shapes and heterogeneous phantom materials except the surface irregularity.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2002.09a
• /
• pp.74-82
• /
• 2002

In Intensity Modulated Radiotherapy (IMRT), radiation is delivered in a multiple of Multileaf Collimator (MLC) subfields. A subfield with a small leaf-to-leaf opening is highly sensitive to a leaf-positional error. We introduce a method of identifying and rejecting IMRT plans that are highly sensitive to a systematic MLC gap error (sensitivity to possible random leaf-positional errors is not addressed here). There are two sources of a systematic MLC gap error: Centerline Mechanical Offset (CMO) and, in the case of a rounded end MLC, Radiation Field Offset (RFO). In IMRT planning system, using an incorrect value of RFO introduces a systematic error ΔRFO that results in all leaf-to-leaf gaps that are either too large or too small by (2ㆍΔRFO), whereas assuming that CMO is zero introduces systematic error ΔCMO that results in all gaps that are too large by ΔCMO = CMO. We introduce a concept of the Average Leaf Pair Opening (ALPO) that can be calculated from a dynamic MLC delivery file. We derive an analytic formula for a fractional average fluence error resulting from a systematic gap error of Δ$\chi$ and show that it is inversely proportional to ALPO; explicitly it is equal to, (equation omitted) in which $\varepsilon$ is generally of the order of 1 mm and Δx=2ㆍΔRFO+CMO. This analytic relationship is verified with independent numerical calculations.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.19 no.5
• /
• pp.340-346
• /
• 1999

Minimum reflection and backward radiation methods on liquid/solid interrace were used to determine the velocity dispersion relation of acoustical surface wave for brass and aluminum substrates and copper/stainless steel nickel/brass, and nickel/aluminum layered substrates. Dispersion data agreed to dispersion characteristics of a generalized Lamb wave. The difference between velocities determined by two phenomena was closely related to the dispersion characteristics. This correspondence was explained by considering the generation mechanism of surface waves and the concept of group velocity.

• Journal of Korean Library and Information Science Society
• /
• v.41 no.3
• /
• pp.269-290
• /
• 2010

Applying one specific thesaurus might cause several problems because each thesaurus has its own characteristics inherited from its construction process. Therefore, integration of thesauri can be an appropriate approach to overcome the difficulties. This current research selected physics as a domain and two thesauri in the domain: PACS and PIRA. By integrating these two heterogeneous thesauri, this research could construct a conceptual structure that covers the whole concepts related to physics. By constructing the conceptual structure with the use of facet analysis from integrated thesaurus, it provides knowledge base with hierarchical structure and clear relationships between concepts. It can be an alternate approach to effective and efficient information retrieval and knowledge discovery.

• Progress in Medical Physics
• /
• v.26 no.2
• /
• pp.59-71
• /
• 2015

The goal of quality assurance (QA) is to minimize systematic errors in order to maintain the quality of a certain process. Statistical process control (SPC) has been utilized for QA in radiation therapy field since 2005 and is changing QA paradigm. Its purpose is to maintain a process within the given control limits while monitoring of error trends such as variation or dispersion. SPC can be applied to all QA aspects of radiotherapy; however, a medical physicist should have enough knowledge about the application of SPC to QC/QA procedures. In this paper, the author introduce a concept of SPC and review some previously reported studies those used SPC for QA in radiation therapy.

• Progress in Medical Physics
• /
• v.31 no.1
• /
• pp.1-7
• /
• 2020

Hadron therapy, such as carbon and helium ions, is increasingly coming to the fore for the treatment of cancers. Such hadron therapy has several advantages over conventional radiotherapy using photons and electrons physically and clinically. These advantages are due to the different physical and biological characteristics of heavy ions including high linear energy transfer and Bragg peak, which lead to the reduced exit dose, lower normal tissue complication probability and the increased relative biological effectiveness (RBE). Despite the promising prospects on the carbon ion radiation therapy, it is in dispute with which bio-mathematical models to calculate the carbon ion RBE. The two most widely used models are local effect model and microdosimetric kinetic model, which are actively utilized in Europe and Japan respectively. Such selection on the RBE model is a crucial issue in that the dose prescription for planning differs according to the models. In this study, we aim to (i) introduce the concept of RBE, (ii) clarify the determinants of RBE, and (iii) compare the existing RBE models for carbon ion therapy.

• Wind and Structures
• /
• v.14 no.4
• /
• pp.337-357
• /
• 2011

The collection of wind speed time series by means of digital data loggers occurs in many domains, including civil engineering, environmental sciences and wind turbine technology. Since averaging intervals are often significantly larger than typical system time scales, the information lost has to be recovered in order to reconstruct the true dynamics of the system. In the present work we present a simple algorithm capable of generating a real-time wind speed time series from data logger records containing the average, maximum, and minimum values of the wind speed in a fixed interval, as well as the standard deviation. The signal is generated from a generalized random Fourier series. The spectrum can be matched to any desired theoretical or measured frequency distribution. Extreme values are specified through a postprocessing step based on the concept of constrained simulation. Applications of the algorithm to 10-min wind speed records logged at a test site at 60 m height above the ground show that the recorded 10-min values can be reproduced by the simulated time series to a high degree of accuracy.