• Journal of the Korean Magnetics Society
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• v.19 no.2
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• pp.62-66
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• 2009

The soft magnetic FeSiCr were processed the ball-mill for 30 hours and the shape of FeSiCr particles was changed from sphere to flake type, which was observed using scanning electron microscope. The complex permittivity and permeability spectra and reflection loss of FeSiCr-rubber composite was measured using Network Analyzer in order to investigate the relationship between the microwave absorption and the material constants. The matching frequency shifted toward lower frequency range with microwave absorber thickness, and microwave absorber with FeSiCr-rubber composite showed a maxium reflection loss of -8.3 dB at 1.86 GHz for a 1.3 mm thickness.

• Journal of the Korean institute of surface engineering
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• v.49 no.3
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• pp.301-306
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• 2016

The effects of nanotexturing and post-etching on the reflection and quantum efficiency properties of diamond wire sawn (DWS) multicrystalline silicon (mc-Si) solar cell have been investigated. The chemical solutions, which are acidic etching solution (HF-$HNO_3$), metal assisted chemical etching (MAC etch) solutions ($AgNO_3$-HF-DI, HF-$H_2O_2$-DI) and post-etching solution (diluted KOH at $80^{\circ}C$), were used for micro- and nano-texturing at the surface of diamond wire sawn (DWS) mc-Si wafer. Experiments were performed with various post-etching time conditions in order to determine the optimized etching condition for solar cell. The reflectance of mc-Si wafer texturing with acidic etching solution showed a very high reflectance value of about 30% (w/o anti-reflection coating), which indicates the insufficient light absorption for solar cell. The formation of nano-texture on the surface of mc-Si contributed to the enhancement of light absorption. Also, post-etching time condition of 240 s was found adequate to the nano-texturing of mc-Si due to its high external quantum efficiency of about 30% at short wavelengths and high short circuit current density ($J_{sc}$) of $35.4mA/cm^2$.

• Korean Institute of Interior Design Journal
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• v.26 no.1
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• pp.75-82
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• 2017

This study reviews the process of creating the patterns through the Christopher Alexander's books to discover the fundamental rules for creation of the pattern language. The essential ideas of 11 rules describing the characteristics of the pattern language are organized by keyword depending on the characteristics of each rule. Then, this study analyzes which keyword was applied importantly and how it had been developed chronologically in the Alexander's books. As a result, 5 keywords - reflection of cultural difference, reflection of human desires, solving the repeated problem, function suitable for principal purpose, and network structure - are applied to his early books in which the pattern language was theoretically developed, the pattern of traditional society was discovered and the network structure was developed. Another 5 keywords - user participation method, new problem solving, structure preserving transformation, post-mechanization method, and central invariant structure - are applied to the books in his mid-term after completion of the pattern theory which discover new pattern for contemporary society and apply the pattern language to time and space. In his later books which organize the theory of pattern language and suggest the direction for using the pattern language, 5 keywords - wholeness, post-mechanization method, user participation method, new problem solving, and structure preserving transformation - are applied. Users may use the pattern language more precisely if he/she considers the keywords of the early period in searching the patterns of existing environment, the keywords of the intermediate period in searching the patterns of new environment or in regard to time and space, and the keywords of the later period in considering direction of the application of the pattern language.

• International Journal of Highway Engineering
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• v.20 no.1
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• pp.87-95
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• 2018

PURPOSES : A geo-grid pavement, e.g., a stress-absorbing membrane interlayer (SAMI), can be applied to an asphalt-overlay method on the existing surface-pavement layer for pavement maintenance related to reflection cracking. Reflection cracking can occur when a crack in the existing surface layer influences the overlay pavement. It can reduce the pavement life cycle and adversely affect traffic safety. Moreover, a failed overlay can reduce the economic value. In this regard, the objective of this study is to evaluate the bonding properties between the rigid pavement and a SAMI by using the direct shear test and the pull-off test. The predicted fractural energy functions with the shear stress were determined from a numerical analysis of the moving average method and the polynomial regression method. METHODS : In this research, the shear and pull-off tests were performed to evaluate the properties of mixtures constructed using no interlayer, a tack-coat, and SAMI with fabric and without fabric. The lower mixture parts (describing the existing pavement) were mixed using the 25-40-8 joint cement-concrete standard. The overlay layer was constructed especially using polymer-modified stone mastic asphalt (SMA) pavement. It was composed of an SMA aggregate gradation and applied as the modified agent. The sixth polynomial regression equation and the general moving average method were utilized to estimate the interlayer shear strength. These numerical analysis methods were also used to determine the predictive models for estimating the fracture energy. RESULTS : From the direct shear test and the pull-off test results, the mixture bonded using the tack-coat (applied as the interlayer between the overlay layer and the jointed cement concrete) had the strongest shear resistance and bonding strength. In contrast, the SAMI pavement without fiber has a strong need for fractural energy at failure. CONCLUSIONS : The effects of site-reflection cracking can be determined using the same tests on cored specimens. Further, an empirical-mechanical finite-element method (FEM) must be done to understand the appropriate SAMI application. In this regard, the FEM application analy pavement-design analysis using thesis and bonding property tests using cored specimens from public roads will be conducted in further research.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.200-206
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• 2008

To implement a mobile radio system, wave-propagation models are necessary to determine propagation characteristics accurately, Currently, the empirical/theoretical prediction models for urban environments are fairly well-developed. But there is a lack of a suitable prediction model for mountain region. So in this paper, to develop the prediction model for mountain region, propagation environments are classified based on three basic mechanisms: reflection, diffraction, penetration(absorbtion and scattering), and measurements have been performed for the classified mountain regions including open area, forest and ridge. Using the measurement data, empirical modeling of propagation characteristics are performed, and then a prediction model for mountain region is proposed.

• Journal of the Korean Society of Earth Science Education
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• v.6 no.3
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• pp.252-260
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• 2013

The purpose of this study is find out the correlation of level of knowledge of pre-service elementary teacher with space perception ability on 'Earth and Space' of elementary science. During the second semester of 2013, for 15 weeks, the classes were conducted for 3 hours per week and we find out knowledge Understanding degree and select terms offered by 5th grade science courses 'The solar system and the stars', 'Earth and Moon', 'change of seasons' section and measured space perception ability degree of pre-service elementary school teacher with a questionnaire. We analyzed the correlation of understanding level of knowledge in the field of astronomy of pre-service elementary school teacher with space perception ability. The results of the study are presented as follows. First, pre-service elementary school teacher showed a low level of knowledge understanding as it goes the upper grades about upper concept in 'The solar system and the stars', 'Earth and Moon', 'change of seasons' section' of astronomy area of elementary science 'Earth and space sector'. The pre-service elementary school teachers needs to acquire knowledge of astronomy area in elementary school curriculum. Second, pre-service elementary school teacher showed that there are differences individually in 'finding solid body' of sub-element of space perception ability. This shows that 'finding solid body' factor is associated with space perception ability. Third, in the section of 'The earth and the Universe' for elementary education, 'Reflection' and 'Finding solid body' which are low-level components of space perception ability were verified that have a corelationship with general grades in the astronomy conception test.

• Journal of the Korean Society of Earth Science Education
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• v.3 no.3
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• pp.239-247
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• 2010

The purpose of this study is to examine the effects of an free inquiry method based on PBL(Problem-Based Learning: PBL) to improve students science process skills and self-directed learning characteristics. To verify this research, twenty-two third-grade students were selected from Chung-ryeol Elementary School located in Busan. They have received pre-test and post-test about their abilities in their science process skills and abilities for self-directed learning characteristics. Also, their self-reflection data was analyzed. The teaching and learning PBL process is to provide the information named 'I am the expert on Earth and Moon' which is recreated by analyzing the science curriculum and characteristics of students from Lesson 3 'Earth and Moon', and to make plans for solving the information with K/NK method. Then, to solve the information is gathered and investigated using the PBL workbook. Lastly, students present their finding using the free inquiry method in a group. The post-test showed following results : first, the free inquiry method based on PBL stimulates inquisitiveness in students about science learning and the research group shows improved science process skill. It shows us that using the free inquiry method based on PBL can be used effects to elevate science process skill. Second, the free inquiry method based on PBL has a positive effect on self-directed learning. The research tells us that using the free inquiry method based on PBL can improve a student self-directed learning characteristics.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.34-41
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• 2009

The latest vehicle yields a superior safety and reduction of driving burden by monitoring the driving state of vehicle and its environment with various sensors. To detect other vehicles and objects of the rear left and right-side blind spot area of driver, provide the information about a existence of objects inside the blind spot, and give a signal to avoid collision, this study proposes the intelligent outside rear-view mirror system. This task has substantially complicated several factors. For example, the size, geometry and features of the various vehicles which might enter the monitored zone is varied widely and therefore present various reflective characteristics. This study proposes the optimal specification and configuration of optical system and IR array sensor of blind spot detection system, and shows the results of the performance evaluation of developed system.

• Journal of Korean Academy of Nursing
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• v.35 no.3
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• pp.555-564
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• 2005

Purpose: This study was done to uncover the nature of hope experienced by clients with chronic schizophrenia. Method: A phenomenological approach developed by Van Manen was adopted. Data was collected from intensive interviews on 7 clients with chronic schizophrenia and the expatients' biographies and arts. A phenomenological reflection was done in terms of the four life world existentials. Result: Corporeality: Perceiving the body feeling better, proudness of self, accepting their own ill body and transcending the limitation of the body, expressing self, and staying within the boundary of a healthy body were disclosed as the body's experience of hope. Spatiality :A place with safety, freedom, peace, and sharing was the space of hope. Temporality :The essential experience of time with hope was the continuity of moving forward amid cycling and moments being filled up with something. Relationality : Connecting with someone, having someone who is dependable, understandable and exchanging interest and love were identified as the relationships of hope with others. Conclusion: The results of this study show that chronic schizophrenic patients always strive hard to keep hope and they really need someone who can support them.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.167-171
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• 2004

The electroless deposition of copper on the hydrogen-terminated Si(111) surface was investigated by means of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, scanning tunneling microscopy (STM), and energy-dispersive spectroscopy (EDS). The hydrogen-terminated Si(111) surface prepared was stable under air atmosphere for a day or more. It was found from ATR-FTIR that two bands centered at 2000 and 2260 $cm^{-1}$ appeared after the H-Si(111) surface was immersed in 40% $NH_4F$ solution containing 10 mM $Cu^{2+}$. On the other hand, STM image included the copper islands with a height of 5 nm and a diameter of 10-20 nm. The EDS data displayed the presence of copper, silicon and oxygen species. The results were rationalized in terms of the redox reaction of surface Si atoms and $Cu^{2+}$ ions in solutions, which are changed into $Si(OH)_x(F)_y$ containing $SiF_6^{2-}$ ions and neutral copper islands.