• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제40회 동계학술대회 초록집
• /
• pp.306-306
• /
• 2011

Three dimensional(3D) topological insulators(TIs) of Bi binary alloys are characterized by a bulk energy gap with strong spin-orbit coupling and metallic surface states protected by time-reversal symmetry. It was reported that film forms of such materials were advantageous over bulk forms due to less defect density and better crystallinity. So far, the films have been prepared on several substrates including semiconductors and graphene. But, there were no studies on metal substrates. For electronic transport experiments and device applications, it is necessary to know epitaxial relation between TIs and metal electrodes. In this study, Atomically flat films of Bi2Se3 were grown on a Au(111) metal substrate by in-situ molecular beam epitaxy. Using home-built scanning tunneling microscope, we observed hexagonal atomic structures which corresponded to the outmost selenium atomic layer of Bi2Se3. Triangular-shaped defects known as Selenium vacancy were also found.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제40회 동계학술대회 초록집
• /
• pp.318-318
• /
• 2011

Etching of an ultrathin aluminum oxide film on NiAl(110) substrate by methanol is studied by home-built scanning tunneling microscopy at room-temperature. We deposited liquid methanol on thin alumina film by using a high speed solenoid valve suitable for deposition of thermally unstable molecules. It is found that only the reflection domain boundary between two domains was preferentially etched by methanol. Since the reflection domain boundary has many oxygen vacancies and irregular structures, judging from the fact, we assume that oxygen vacancies cause the chemically reactive phenomena of methanol in reflection domain boundary on an alumina film. The reactivity of the reflection domain boundary is attributed to the oxygen vacancies due to irregular structures. Similar reactivity is found on the oxygen deficient alumina produced on top of the intact alumina.

• KIEAE Journal
• /
• 제4권4호
• /
• pp.27-34
• /
• 2004

As number of new housing construction has been growing, the increasing number of people experiencing from Sick Building Syndrome (SBS) is distinct. The purpose of this study is to examine the symptoms reported by residents responses to cope with the syndrome and to investigate their environmental characteristics considered relevant to the syndrome. Respondents were housewives living in apartments and were more likely to stay at home. 170 data were collected by both web-based internet survey and conventional questionnaire survey. The findings revealed that the symptom appeared very diverse and composite. The most common symptom was eye irritation. Among diverse coping behaviors, ventilation was most popular.

• 전기의세계
• /
• 제18권2호
• /
• pp.7-14
• /
• 1969

From the first customer located right at the substation to the last customer at the end of the line, voltage must be held within close limits, so the voltage regulation is more important than the thermal limit. On a typical distribution system during the peak load period, the voltage drop may be serious enough to cause unsatisfactory operation of home appliances in the residential area, and present many problems to manufacturing industries, where the voltage must be maintained within close limits to insure smooth operation. Among all the factors contributing to voltage drop in the distribution system, the voltage drop in the distribution transformer may account for 30% of this figure. If we can eliminate this factor, the power companies can provide better quality electricity to more customers with the existing distribution facilities, thus saving on initial investment costs. Taking all these problems into consideration, the author undertook the design of a capacitive transformer which would give zero voltage drop at rated load and at 80% lagging power factor while incorporating overload features to withstand 400% overload for at least 100 seconds. The following are the results obtained through design, manufacture and test of an initial experimental transformer built with these specific purposes.

• Journal of the Optical Society of Korea
• /
• 제12권3호
• /
• pp.170-173
• /
• 2008

In this study, we simulated a statistical model of FCS(fluorescence correlation spectroscopy) based on a Poisson process to understand and explain observations of the experiment performed on molecules of ultra-low concentration by the home-built laser-scanning confocal microscope. The statistical model confirmed that the relative mean square amplitude of fluctuations is shown to be inversely proportional to the average number of molecules, even in the ultra-low concentration, if some conditions are satisfied. Signal-to-noise ratio and the variability of dwelling time under the confocal volume were found to be effective conditions for the experiment.

• Current Photovoltaic Research
• /
• 제1권1호
• /
• pp.33-37
• /
• 2013

LCPV modules under 5 suns consist of reflective optics and receiver modules, similar to a typical fixed concentration PV module. If they are to be used as a compound parabolic concentrator, which is filled with a dielectric material, a compact plate structure of the fixed CPV can be designed and built at a large acceptance angle. These types of flat-$plate{\mu}$-LCPV modules are suitable for building integrated photovoltaic modules, facade applications, mobile devices, and small home appliances. Therefore, in this study, the possibilities for other application devices were studied and presented by designing and fabricating LCPCs for CPV modules.

• 로봇학회논문지
• /
• 제2권3호
• /
• pp.227-233
• /
• 2007

Representing an environment as the probabilistic grids is effective to sense outlines of the environment in the mobile robot area. Outlines of an environment can be expressed factually by using the probabilistic grids especially if sonar sensors would be supposed to build an environment map. However, the difficult problem of a sonar such as a specular reflection phenomenon should be overcome to build a grid map through sonar observations. In this paper, the NRF(Neighborhood Recognition Factor) was developed for building a grid map in which the specular reflection effect is minimized. Also the reproduction rate of the gird map built by using NRF was analyzed with respect to a true map. The experiment was conducted in a home environment to verify the proposed technique.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 추계학술대회 논문집
• /
• pp.503-509
• /
• 2004

With modem computational fluid dynamics method (CFD), air-charging models of the air brake pipe system and auxiliary reservoir are built. Compared with one-dimension model, no empirical formula is introduced to solve branch pipe fields for two-dimension model. A modified operator-splitting method is presented to solve the coupled equations of pressure and velocity, and numerical simulation shows that it is very stable. Compare the numerical results with empirical data of heavy haul trains in home and abroad so as to prove the correctness of the theory and algorithm presented. This paper gives theoretic reference to the experiments of braking effects of heavy haul trains, and forms a basis for development of complete freight train air brake system simulation.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
• /
• 제6권11호
• /
• pp.47-57
• /
• 2000

In western countries, the community care for the elderly people has developed, because of heavy cost and isolation problem in the society of institutional care basis. Since 1980, 'home care for the elderly' has introduced in korea. One of them is 'Multipurpose senior center'. However it has built without rational space programming and architectural planning analysis. Therefor, this study is to establish the function and space programming of multipurpose senior center.

• 대한화학회지
• /
• 제59권2호
• /
• pp.132-135
• /
• 2015

Bonding force and stiffness in amine-linked single-molecule junctions for Ag electrodes were measured using a home-built conducting atomic force microscope under ambient conditions at room temperature. For comparison, Au electrodes were used to measure the rupture force and stiffness of the molecular junctions. The traces of the force along with the conductance showed a characteristic saw-tooth pattern owing to the breaking of the metal atomic contacts or the metal-molecule- metal junctions. We found the rupture force and stiffness for Ag are smaller than those for Au electrodes. Furthermore, we observed that the force required to break the amine-Ag bond in the conjugated molecule, 1,4-benzenediamine, is smaller than in 1,4-butanediamine which is fully saturated. These results consist with the previous theoretical calculations for the binding energies of the nitrogen bonded to Ag or Au atoms.