• Journal of Magnetics
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• v.11 no.4
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• pp.156-159
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• 2006

We have studied the magnetic properties of the CuNi nanoparticles for three different sizes prepared by plasma and chemical techniques. The magnetization is enormously enhanced with decreasing the nanoparticle size. This enhanced magnetic moment shows almost inversely linear temperature dependence, which could be interpreted by the Langevin-type superparamagnetism. The field dependence exhibits ferromagnetic-like behavior with weak hysteresis, which could described in terms of uncompensated spin and/or surface anisotropy. In addition, the magnetic data suggest that the CuNi nanoparticles produced by the plasma method result in significantly less oxidized metallic nanoparticles than those prepared by other techniques.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.337-340
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• 2001

We show that the microstrip ring with a narrow gap exhibits a photonic band gap (PBG) that is generally believed to be created by a periodic array. The discontinuity of impedance at the narrow gap induces the multiple reflections with fixed phase correlation necessary to make the PBG. We have also discussed the tuning of the PBG frequency by applying an external voltage on a varactor mounted on the gap and the applications of this PBG ring as a tunable bandstop filter and a microwave switch.

• Journal of Sensor Science and Technology
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• v.27 no.1
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• pp.36-39
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• 2018

Transparent olivine $LiNiPO_4$ thin films on sapphire substrates were fabricated by radio frequency (RF) magnetron sputtering. The X-ray diffraction patterns show these thin films have the phase of $LiNiPO_4$ with an ordered olivine structure indexed to the orthorhombic Pmna space group. $LiNiPO_4$ thin films deposited on sapphire substrates exhibit transmittance of about 83 %. It was confirmed that the $LiNiPO_4$ thin film exhibits a high potential of 5 V-class.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.367-370
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• 2015

Monolayer transition metal dicalcogenide (TMDC) materials are currently attracting extensive attention due to their distinctive electronic, transport, and optical properties. For example, monolayer $MoS_2$ exhibits a direct band gap in the visible frequency range, which makes it an attractive candidate for the photocatalytic water splitting. For the photoelectrochemical water splitting, the appropriate band edge positions that overlap with the water redox potential are necessary. Similarly, appropriate band level alignments will be crucial for the light emitting diode and photovoltaic applications utlizing heterojunctions between two TMDC materials. Carrying out first-principles calculations, we here investigate how the band edges of $MoS_2$ can be adjusted by surface ligand functionalization. This study will provide useful information for the realization of ligand-based band engineering of monolayer $MoS_2$ for various electronic, energy, and bio device applications.

• Journal of electromagnetic engineering and science
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• v.9 no.1
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• pp.12-16
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• 2009

This paper presents a new iterative locally one-dimensional [mite-difference time-domain(LOD-FDTD) method that has a simpler formula than the original iterative LOD-FDTD formula[l]. There are fewer arithmetic operations than in the original LOD-FDTD scheme. This leads to a reduction of CPU time compared to the original LOD-FDTD method while the new method exhibits the same numerical accuracy as the iterative ADI-FDTD scheme. The number of arithmetic operations shows that the efficiency of this method has been improved approximately 20 % over the original iterative LOD-FDTD method.

• Journal of the Korean earth science society
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• v.32 no.1
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• pp.124-139
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• 2011

This study was to explore epistemological features presented in texts of exhibit panels in the science museum located in Gyeonggi Province. Out-of-school or daily experiences allow more properly and potentially students to form informative science image, because the understandings of scientific epistemology were constructed tacitly through various experiences over a long period of time. The target for this study was panel texts of exhibits in a science museum as an of out-of-school context. The analytical framework was adopted from epistemological frameworks by Ryder et al. (1999). The research results were explored in the categories of relationship between scientific knowledge claims and the data, the nature of lines of scientific enquiry, and social dimension of science. It revealed that one exhibit might reflect the characteristics of one epistemological position: relating one data to one knowledge claim; generating knowledge claim from scientists' individual interests or from discipline's internal epistemology; scientists working as a community or an institution. Findings suggested that the exhibits of a science museum including panel texts and medium need to reflect the wide ranges of scientific epistemology.

• Journal of the Korean earth science society
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• v.26 no.5
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• pp.376-386
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• 2005

This study investigated to describe how the nature of science is revealed in the four natural history museums in Korea. Natural history museums are well considered as informal settings of education, and the nature of science has been one of major topics stressed in science education. Therefore, the revelation of this topic is supposedly reflected in developing museum exhibitions. In each of the four target natural history museum or natural history exhibition, the representative exhibits subtitled by scientific inquiry and cases dealing with history of science were selected for the study. The analyzing exhibits focused on whether exhibitions were labeled with emphasis on declarative description or interpretative one. In analyzing the contents, the focus was on the concerns of scientists, scientific community, social and cultural aspects, uncertainty of scientific knowledge, and providing sufficient evidences. All things considered, it was hard to conclude that every target exhibit clearly considered the nature of science as an essential element, in designing and developing their exhibitions. More deliberate input of nature of science is suggested for worldly renowned natural history museums, because previous researches keep insisting that the nature of science would be more efficiently achieved in an informal educational setting rather than in classrooms.

• Journal of The Korean Association For Science Education
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• v.27 no.9
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• pp.832-847
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• 2007

The purpose of the study was to analyze and interpret parent-child dyadic discourses in depth with emphases on the ZPD system in a museum, an informal learning setting. Second graders and their parents from Seoul and its environs were voluntarily participated in the study. Data were collected from the museum documents, the photos of exhibits, and the video recordings of dyadic discourses at and between exhibits. The documents and the photos were analyzed to investigate what the topics, medium and goals of the exhibits were. The video recordings were all transcribed and analyzed to understand what and how they talked to each other through the lens of the ZPD system; situation definition, intersubjectivity, and semiotic mediation, The results of the study consisted of two parts. First, it showed that parent-child dyadic discourses were categorized in four: (1) within the actual developmental level; (2) in the zone of proximal development; (3) toward the potential developmental level; and (4) out of developmental level. The most common categories were the dyadic discourses within the actual developmental level and in the zone of proxima I development. Second, the representative cases in each categories were described and interpreted to understand the nature of parent-child dyadic discourses. It can be concluded that we gained some important understandings of an intrinsic attribute of parent-child discourses in a museum, an informal learning setting. Based on the results of the study, it can be suggested that museums make efforts to cultivate the affordance of exhibit environment to promote visitor's learning.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.582-584
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• 2004

The light-emitting properties of poly(2-triethylgermyl-1,4-phenylenevinylene) (TEG-PPV) are compared with those of the silyl-substituted PPV homologue, poly(2-trimethylsilyl-1,4phenylenevinylene) (TMS-PPV). The precursor polymer is solution-processable. After carrying out thermal elimination on the precursor polymer film, the resulting fully conjugated polymer film was found to exhibit high thermal stability in air, and absorption that is shifted to the longer wavelength region owing to the extension of the n-conjugated system. TEG-PPV exhibits efficient green light emission; the maximum PL emission of a TEG-PPV thin film was found to be at 515 nm. The HOMO and LUMO energy levels were also determined using photo-emission spectroscopy. The performance of the TEG-PPV EL device was found to be comparable to that of the TMS-PPV device.

• Biomedical Science Letters
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• v.23 no.4
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• pp.380-387
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• 2017

Berchemia berchemiaefolia (BB) are climbing plants or small to medium-sized trees that live in Africa, Asia and America. We performed the present study to investigate whether oral administration of Berchemia berchemiaefolia extract (BBE) protects SD rats from pain. The SD rat experimental groups were divided into four groups. Two of the animal model groups were fed on BBE (200 mg/kg or 100 mg/kg). We performed oral acute toxicity test to determine the optimal oral dose of BBE. To explore if BBE alleviated pain in the SD rat, we undertook the tail flick latency test and formalin test. Additionally, we conducted the anti-oxidative test. The findings of the present study suggest that Berchemia berchemiaefolia extract exhibits strong antioxidant and analgesic activities.