• Journal of the Korean Ceramic Society
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• v.37 no.7
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• pp.686-692
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• 2000

Tin-doped In2O3 (ITO) films were fabricated using a d.c. magnetron reactive sputteirng of a In-10 wt% Sn alloy target in an Ar and O2 gas mixture. To understand the behavior of the carrier mobility in ITO films with O2 partial pressure, the resistivity, carrier concentration and mobility, film density, and intrinsic stress in the films were measured with O2 partial pressure. It was found experimentally that the carrier mobility increased rapidly as the film density increased. In the ITO film with the density close to theoretical one, the mean free path was the same as the columnar diameter. This indicated that the mobility in ITO films was strongly influenced by the crystall size. However, in the case where the film density was smaller than a theoretical density, the mean free paths were also smaller the columnar diameter. It was analyzed that the electron scattering at pores and holes within the crystalline was the major obstacle for electron conduction in ITO films. The measurement of intrinsic stress in ITO films also made it clear that the density of ITO films was controlled by the bombardment of oxygen neutrals on the growing film.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.65.4-65.4
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• 2017

The laboratory astrophysics is a new emerging field of basic sciences, and has tremendous discovery potentials. The laboratory astrophysics investigates the basic physical phenomena in the astrophysical objects in controlled and reproducible manners, which has become possible only recently due to the newly-established intense photon and ion beam facilities worldwide. In this presentation, we will introduce several promising ideas for laboratory astrophysics programs that might be readily incorporated in the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL). For example, precise spectroscopic measurements using Electron Beam Ion Trap (EBIT) and intense X-ray photons from the PAL-XFEL can be performed to explore the fundamental processes in high energy X-ray phenomena in the visible universe. Besides, in many violent astrophysical events, the energy density of matter becomes so high that the traditional plasma physics description becomes inapplicable. Generation of such high-energy density states can be also be achieved by using the intense photon beams available from the PAL-XFEL.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1602-1605
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• 2008

We considered most general electron emission caused by temperature as well as electric field with a free electron gas model. The total electron emission current density comes from field emission effect where electron energy is lower than vacuum and from thermionic emission effect where electron energy is higher than vacuum. The total electron emission current density is shown as a function of temperature for constant electric field, and as a function of electric field for constant temperature.

• The Korean Journal of Rheology
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• v.10 no.4
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• pp.256-258
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• 1998

An experimental study was done to improve the processability and optical property of linear low density polyethylene(LLDPE) film. By modifying the molecular structure of LLDPE with electron beam we could get the improved processability and optical property of film. By appropriate dosing of electron beam and a small addition of UV-stabilizer it was possible to produce gel-free film with low haze. The proceassability was also improved.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.235.2-235.2
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• 2014

Plasma hardly grows in low pressure because of lack of collision. Especially, in extremely low pressure like 1 mTorr, the experiment scale is far larger than mean free path therefore plasma is hardly generated in such low pressure. But low pressure plasma has useful properties like low damage or fine sputtering process because it has typically low electron density. In here, thermal electron is used to make breakdown in low pressure easily and cylindrical geometry is used to help discharge easily. And we changed magnetic field strength to control electron density or temperature. In low pressure, density and temperature behavior is very interesting so its characteristics are examined here.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.216-223
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• 2017

In this work, linear and mass attenuation coefficients, effective atomic number and electron density, mean free paths, and half value layer and $10^{th}$ value layer values of barium-bismuth-borosilicate glasses were obtained for 662 keV, 1,173 keV, and 1,332 keV gamma ray energies using MCNP-4C code and XCOM program. Then obtained data were compared with available experimental data. The MCNP-4C code and XCOM program results were in good agreement with the experimental data. Barium-bismuth-borosilicate glasses have good gamma ray shielding properties from the shielding point of view.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.156-156
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• 2000

Recently, the surface electronic states have attracted much attention since their standing wave patterns created around steps, defects, and adsorbates on noble metal surfaces such as Au(111), Ag(110), and Cu(111) were observed by scanning tunneling microscopy (STM). As a typical example, a striking circular pattern of "Quantum corral" observed by Crommie, Lutz, and Eigler, covers a number of text books of quantum mechanics, demonstrating a wavy nature of electrons. After the discoveries, similar standing waves patterns have been observed on other metal and demiconductor surfaces and even on a side polane of nano-tubes. With an expectation that the surface states could be utilized as one of ideal cases for studying two dimensionakl (sD) electronic system, various properties, such as mean free path / life time of the electronic states, have been characterized based on an analysis of standing wave patterns, . for the 2D electron system, electron density is one of the most importnat parameters which determines the properties on it. One advantage of conventional 2D electron system, such as the ones realized at AlGaAs/GaAs and SiO2/Si interfaces, is their controllability of the electrondensity. It can be changed and controlled by a factor of orders through an application of voltage on the gate electrode. On the other hand, changing the leectron density of the surface-state 2D electron system is not simple. On ewqy to change the electron density of the surface-state 2D electron system is not simple. One way to change the electron density is to deposit other elements on the system. it has been known that Pd(111) surface has unoccupied surface states whose energy level is just above Fermi level. Recently, we found that by depositing Pd on Cu(111) surface, occupied surface states of Cu(111) is lifted up, crossing at Fermi level around 2ML, and approaches to the intrinsic Pd surface states with a increase in thickness. Electron density occupied in the states is thus gradually reduced by Pd deposition. Park et al. also observed a change in Fermi wave number of the surface states of Cu(111) by deposition of Xe layer on it, which suggests another possible way of changing electron density. In this talk, after a brief review of recent progress in a study of standing weaves by STM, I will discuss about how the electron density can be changed and controlled and feasibility of using the surface states for a study of 2D electron system. One of the most important advantage of the surface-state 2D electron system is that one can directly and easily access to the system with a high spatial resolution by STM/AFM.y STM/AFM.

• Transactions on Electrical and Electronic Materials
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• v.1 no.1
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• pp.32-39
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• 2000

Langmuir probe measurements of electron density, electron temperature and potential are mad in the early stage (<5${\mu}$s) of a laser ablated plasma plume, in which a positive current form positive ions and a electron current are overlapped. The plasma wes produced by focusing the second harmonic, 532 nm, of Q-switched Nd:YAG laser on a high purity carbon target. Then the laser intensity on the target of ~1.6${\times}$10$\^$15/ W/$\textrm{cm}^2$. The measured electron desities and temperatures are ~2${\times}$10/sip 11/ cm$\^$-3/ and -3 eV. In particluar , the phenomenon that the electron temperature decreased and then increased was observed,. It could be well explained that this phenomenon occurred in the process of inverse Bremsstrahlung of free electrons in plasma. Additionally, the plasma potential(>11V) was higher than the published values.

• Journal of Plant Biology
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• v.34 no.3
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• pp.201-213
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• 1991

This study has been carried out to investigate the ultrastructural changes, formation of storage materials in endosperm cells with electron microscope during the seed formation of Panax ginseng C.A. Meyer. In the early stage of seed formation with green seed coat, the endosperm was cellular type. Cell plate was largely composed of dictyosome vesicles in early stage of wall formation after mitosis. Central vacuole was gradually subdivided into several small-sized vacuoles. During the differentiation of plastids, some proplastid was replaced by amyloplast with starch grains and lamellar structure. A number of mitochondria with well developed cristae were distributed in cytoplasm. Rough endoplasmc reticulum, dictyosome, microbody, free ribosomes and polysomes were evenly distributed in cytoplasm. Spherical spherosomes were formed from dictyosome containing the lipid materials of even electron density. Protein bodies were formed by interfusing between vacuoles and vesicles derived from rough endoplasmic reticulum which contained the amorphous protein of high electron density.

• Applied Science and Convergence Technology
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• v.27 no.5
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• pp.90-94
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• 2018

The electron band structure of manganese-adsorbed graphene on an SiC(0001) substrate has been studied using angle-resolved photoemission spectroscopy. Upon introducing manganese atoms, the conduction band of graphene, that is observed in pristine graphene indicating intrinsic electron-doping by the substrate, completely disappears and the valence band maximum is observed at 0.4 eV below Fermi energy. At the same time, the slope of the valence band decreases by the presence of manganese atoms, approaching the electron band structure calculated using the local density approximation method. The former provides experimental evidence of the formation of nearly free-standing graphene on an SiC substrate, concomitant with a metal-to-insulator transition. The latter suggests that its electronic correlations are efficiently screened, suggesting that the dielectric property of the substrate is modified by manganese atoms and indicating that electronic correlations in grpahene can also be tuned by foreign atoms. These results pave the way for promising device application using graphene that is semiconducting and charge neutral.