• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.505-509
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• 2011

Visible light-activated photocatalysts (based on doped titania) are the subject of intensive current research due to the promise they offer in relation to solar powered systems for photocatalysis, hybrid systems for $CO_2$ conversion and hydrogen production from water. Current synthetic methodologies suffer from one or more serious shortcomings, which seriously hinder practical application. These include high cost, irreproducibility, difficulty in controlling the dopant level and unsuitability for scale up. In this review new reproducible and controllable methods (developed by Lambert group, Cambridge University) allowing the synthesis of practical quantities of efficient, visible light active anion (e.g. N, C and B) doped $TiO_2$ photocatalysts are summarized.

• Journal of The Korean Astronomical Society
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• v.35 no.1
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• pp.35-40
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• 2002

Gaudi, Naber & Sackett pointed out that if an event is caused by a lens system containing more than two planets, all planets will affect the central region of the magnification pattern, and thus the existence of the multiple planets can be inferred by detecting additionally deformed anomalies from intensive monitoring of high magnification microlensing events. Unfortunately, this method has important limitations in identifying the existence of multiple planets and determining their parameters (the mass ratio and the instantaneous projected separation) due to the degeneracy of the resulting light curve anomalies from those induced by a single planet and the complexity of multiple planet lensing models. In this paper, we propose a new channel to search for multiple planets via microlensing. The method is based on the fact that the lensing light curve anomalies induced by multiple planets are well approximated by the superposition of those of the single planet systems where the individual planet-primary pairs act as independent lens systems. Then, if the source trajectory passes both of the outer deviation regions induced by the individual planets, one can unambiguously identify the existence of the multiple planets. We illustrate that the probability of successively detecting light curve anomalies induced by two Jovian-mass planets located in the lensing zone through this channel will be substantial. Since the individual anomalies can be well described by much simpler single planet lensing models, the proposed method has an important advantage of allowing one to accurately determine the parameters of the individual planets.

• Advances in environmental research
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• v.3 no.1
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• pp.11-28
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• 2014

Advanced oxidation processes using UV and catalysts like $TiO_2$ and ZnO have been recently applied for the photocatalytic degradation of MTBE in water. Attempts have been made to replace the UV radiation by the solar spectrum. This review intends to shed more light on the work that has been done so far in this area of research. The information provided will help in crystallizing the ideas required to shift the trend from UV photocatalysis to sunlight photocatalysis. The careful optimization of the reaction parameters and the type of the dopant employed are greatly responsible for any enhancement in the degradation process. The advantage of shifting from UV photocatalysts to visible light photocatalysts can be observed when catalysts like $TiO_2$ and ZnO are doped with suitable metals. Therefore, it is expected that in the near future, the visible light photocatalysis will be the main technique applied for the remediation of water contaminated with MTBE.

• Journal of The Korean Astronomical Society
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• v.26 no.2
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• pp.115-134
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• 1993

The light curve and radial velocity curve of multiperiodic dwarf cepheid VI719 Cyg (HD200925) with peculiar light curve have been reanalyzed in order to identify the oscillation modes to confirm the helium settling within the envelope. To do these, through the period search for the photometric and radial velocity data from the literature, two different periods were determined and the oscillation modes corresponding to the first and second periods were identified as the fundamental and first radial overtones. Hence the helium settling within the envelope was confirmed from the period ratio. The color excess, metallicity, effective temperature, and surface gravity corresponding to two different modes were determined and it was found that these parameters almost do not depend upon different oscillation mode. By utilizing the surface brightness method, we investigated the variation of angular diameter and radial displacement and it was found that the angular variation is very peculiar. Also by referring to the stellar models, mass and age were determined as $2.7M_{\bigodot}$ and 0.42 Gyr respectively which make this variable star heavier and younger than other multimode dwarf cepheids. Preliminary spectroscopic CCD observations were carried out and it was found that Mg in VI719 Cygni is nearly solar abundent according to the analysis of $5172.68{\AA}MgI$ line which is inconsistent with the photometric result. It was suggested that VI719 Cyg may be classified as a $\rho$ Pup stars according to the photometric characteristics.

• Journal of the Korean Ceramic Society
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• v.49 no.1
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• pp.130-133
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• 2012

In this work we report investigation results of enhanced visible light photocatalytic properties of CdS and CdSe sensitized $TiO_2$ nanotube heterostructures. Anodically grown ordered $TiO_2$ nanotube arrays were sensitized with CdS and CdSe by using successive ionic layer adsorption and reaction method. Photocatalytic measurements revealed that heterostructured samples show enhanced photocurrent density under the visible light illumination. Improved visible light performance of the heterostuctures was explained by lower band gap of the CdS and CdSe and their favorable conduction band positions relative to $TiO_2$. Moreover, due to the lower band gap of the CdSe (1.7 eV) compared to CdS (2.4 eV), both photocurrent density and photoconversion efficiency results showed superior activity.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.24.2-24.2
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• 2009

We present the results of new CCD photometry for the contact binary BX Peg, made during three successive months beginning on September 2008. As do historical light curves, our observations display an O'Connell effect and the November data by themselves indicate clear evidence for very short-time brightness disturbance. For these variations, model spots are applied separately to the two data set of Group I (Sep.--Oct.) and Group II (Nov.). The former is described by a single cool spot on the secondary photosphere and the latter by a two-spot model with a cool spot on the cool star and a hot one on either star. These are generalized manifestations of the magnetic activity of the binary system. Twenty light-curve timings calculated from Wilson-Devinney code were used for a period study, together with all other minimum epochs. The complex period changes of BX Peg can be sorted into a secular period decrease caused dominantly by angular momentum loss due to magnetic stellar wind braking, a light-travel-time (LTT) effect due to the gravitational effect of a low-mass third companion, and a previously unknown short-term oscillation. This last period modulation could be produced either by a second LTT orbit with a period of about 16 yr due to the existence of a fourth body or by the effect of magnetic activity with a cycle length of about 12 yr.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.136-141
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• 2009

Considerable part of energy consumption is occurred by through buildings. Especially, Lighting energy consumption is most part of one in building. There is very various ways and systems for saving lighting energy. In method, It can be divided Passive Daylighting System and Active Daylighting System. Louver, Screen and use of window's character is representative ways of passive system. Reflection mirror, optical pipe and optical fiber is representative method of active system. Introducing day light on which place can't be introduced day light by typical method is important advantage of active system. Except introducing day lighting methods, efficient lighting management system can save lighting energy. It called lighting automation system. Representatively, Occupancy-related automation and Brightness-related automation system is that. According to occupancy and introducing daylighting level properly operate lamp's intensity of illumination that can save lots of energy. Though Introducing daylighting method, effective lighting system we can get proper intensity of illuminance level and energy saving.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.148-154
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• 2009

By the skyscraper building, increase of skin area and expansion of curtain wall system will be the important factors of acceleration in extending supply of BIPV system. In the future interior environmental evaluation is not a necessary to the residents but an essential term which will bring enormous influence. In the interior environmental evaluation, natural light will let the residents with direct contact with outside circumstances and make them feel opened. also only the daylight has radiant energy and color rendering that will have a great influence to residents' mental, operation efficiency and advancing productivity. This research compares and analyzes BIPC system in office spaces with two general sunlight's module. In addition to natural light's efficiency for BIPC system's comfort and confirmed economical efficiency will be applied to basic research data. Hence forth, ensuring indoor intensity of illumination and controlling light system to reducing energy research data will be demanded to increase the amount of supplying BIPC system. Also continuance research in the possibility of applying BIPC system in various buildings, room temperature affected by location of windows and its condensation, and economical evaluation will be required.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.32.1-32.1
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• 2010

The BVR CCD observations of the solar-type contact binary GW Cephei, known as very active dynamically and photometrically, has been made for 20 nights from Nov. 03, 2008 to Dec. 31, 2008 with 1-m reflector of Jincheon station of Chungbuk National University Observatory. A total of 2035 measurements (B: 647, V: 722, R: 666) were obtained to secure new multi-color light curves. From our observations fifteen times of minimum light were newly determined. In this paper both a new period study and an intensive light synthesis were made. Our results will be compared and discussed with the latest thorough studies of the system by Lee et al. (2010).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1218-1223
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• 2004

Porous silicon materials have been shown to have bright prospects for applications in light emitting, solar cell, as well as light- and chemical-sensing devices. In this report, structures of porous silicon prepared by anodic etching in HF-based solution with various etching times were studied in detail by Atomic Force Microscopy and Small Angle X -ray Scattering technique using the high energy beam line at Pohang Light Source in Korea. The results showed the coexistence of the various pores with nanometer and submicrometer scales. For nanameter size pores, the mixed ones with two different shapes were identified: the larger ones in cylindrical shape and the smaller ones in spherical shape. Volume fractions of the cylindrical and the spherical pores were about equal and remained unchanged at all etching times investigated. On the whole uniform values of the specific surface area and of the size parameters of the pores were observed except for the larger specific surface area for the sample with the short etching time. The results implies that etching process causes the inner surfaces to become smoother while new pores are being generated. In all SAXS data at large Q vectors, Porod slope of -4 was observed, which supports the fact that the pores have smooth surfaces.