• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.16-20
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• 2016

In this work, we describe the synthesis and infrared light reflecting characteristics of $TiO_2$/mica hybrid composites. $TiO_2$/mica composite materials were obtained by the hydrolysis and condensation reaction of titanium isopropoxide in an aqueous solution of acetic acid in the presence of mica particles. Amorphous phase of $TiO_2$ on the surface of mica was converted to the crystalline rutile phase via anatase phase by heat treatment ($600-1000^{\circ}C$, 1-3 h) of $TiO_2$/mica composite materials, and the size of crystals was controlled by heat treatment conditions. Physicochemical properties of mica and $TiO_2$/mica composites were investigated using FE-SEM, ED-XRF, and PXRD. The solar reflectance of $TiO_2$/mica composites in the near IR region (780~2,500 nm) measured using a diffuse reflectance NIR spectrophotometer was 88.6%, which is rather higher than that of calcined pure mica (86.6%). Therefore, $TiO_2$/mica composites can be used as NIR light reflective pigments.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.140-145
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• 2012

The purpose of this study is to understand the change of impression by comparing the uniformity lighting with the compound lighting. In previous study, we proposed a light controlling method to harmonize daylight from a window and artificial lights from a ceiling and obtained the results to support our method. We referred this method as the Adjusted Compound-Lighting Model (AC Model). The model claims that lighting in a room with a side-window are perceived as harmonious when the overall light distribution in the room is well approximated by a compound of lights from the window and the entire ceiling. The experiment is carried out with the scaled-models and mock-up spaces that were supposed to be an office space. One is lit by the uniform lighting and the other by the compound lighting in each experimental space. In order to present varying illuminance distributions, thetwo variables were used in this study. One was the ratio of thelight from the window and ceiling in the standard and evaluation box. The standard box was provided by the ratio of 20% to 40% from the window and 80% to 60% from the ceiling as two lighting ratio patterns [Wu20(=Cu80) and Wu40(=Cu60)]. And the evaluation box was provided by the light ratio of 0% to 40 from the window and 100% to 60% from the ceiling [Wcp0(=Ccp100), Wcp20(=Ccp80) and Wcp40(=Ccp60)]. The other variable was themean illuminance level in both boxes. Two level of mean illuminance (700lx and 300lx) were used in this experiment. Each lighting condition was established at equal horizontal mean illuminance level, held constant near 700lx or 300lx in both boxes. Both of them were similar in the shape of distribution when there were same ratios of lights from the window and the ceiling. Subjects were asked to evaluate the point of difference by semantic differential rating on their overall impression after comparing with two rooms. The results showed that the impressions of compound lighting were more positive score than that of uniformity lighting on the items of 'dim-bright', 'dislike-like', 'artificial-natural' and 'closed-open', and that there was no significant difference in impressions between two spaces on other items.

• Analytical Science and Technology
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• v.28 no.1
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• pp.33-39
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• 2015

CdS-QD particles are a nano-sized semiconducting crystal that emits light. Their optical properties show great potential in many areas of applications such as disease-diagnostic reagents, optical technologies, media industries and solar cells. The wavelength of emitting light depends on the particle size and thus the quality control of CdS-QD particle requires accurate determination of the size distribution. In this study, CdS-QD particles were synthesized by a simple ${\gamma}$-ray irradiation method. As a particle stabilizer polyvinyl pyrrolidone (PVP) were added. In order to determine the size and size distribution of the CdS-QD particles, sedimentation field-flow fractionation (SdFFF) was employed. Effects of carious parameters including the the flow rate, external field strength, and field programming conditions were investigated to optimize SdFFF for analysis of CdS-QD particles. The Transmission electron microscopy (TEM) analysis show the primary single particle size was ~4 nm, TEM images indicate that the primarty particles were aggregated to form secondary particles having the mean size of about 159 nm. As the concentration of the stabilizer increases, the particle size tends to decrease. Mean size determined by SdFFF, TEM, and dynamic light scattering (DLS) were 126, 159, and 152 nm, respectively. Results showed SdFFF may become a useful tool for determination of the size and its distribution of various types of inorganic particles.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.152-162
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• 2017

A hydrophilic coating solution was prepared by adding a silane coupling agent and a nano-inorganic oxide in aqueous surfactant solution to increase the efficiency of photovoltaic power generation due to the introduction of antifogging and antifouling properties on the glass surface of the solar cell module. Addition of $Ludox^{(R)}$, a nano-inorganic oxide, to 1% hydrophilic coating solution showed improved hydrophilicity and excellent antifogging effect regardless of $Ludox^{(R)}$ concentration. However, the antifouling effect on the glass surface was showed only when Ludox was added more than 10%. In the case of addition of 0.7% of hydrolyzed TEOS at pH 4, the antifogging effect was maintained as a result of the steam test as well as the antifouling effect even after the coated glass surface was rubbed 100 times with a wet Kimwipe. In addition, from the surface roughness ($R_q$) calculated using AFM data, the higher surface roughness with irregular surface shape was obtained with the higher concentration of TEOS. The addition of 0.7% of TEOS showed relatively high surface roughness and well organized surface condition which can help to improve transmittance of light. In conclusion, $Ludox^{(R)}$ is not required only for the antifogging property. However, at least 10% of Ludox should be added to show antifouling effect and 0.7% of TEOS should be added for good durability.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.19-28
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• 2011

This study developed a solar radiation reflection pavement, so called a cool pavement, to lessen the urban heat island effect by coating a pavement surface with acrylic resins mixed with light-colored pigments. From a laboratory test, simulating solar heating process in pavements, the cool pavement reduced more than $12^{\circ}C$ of pavement temperature at $60^{\circ}C$ compared to a control porous pavement. With the increase of the mixing ratio of the pigments to acrylic resins, the temperature reduction effect increased, but its workability became worse due to higher viscosity. As a result, an appropriate mixing ratio was determined as 15%. The cool pavement had better durability than the control pavement: One quarter of Catabro loss and twofold dynamic stability. Its adhesion was also higher enough not to be debonded under traffic loading. In-situ noise and friction tests conducted in two field sites showed that the cool pavement reduced its noise level by 3.7dB in average and increased its friction level by 30% compared to the control pavement. The permeability of the cool pavement was little lower than the control pavement, but higher enough to satisfy the minimum requirement for porous pavements.

• Macromolecular Research
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• v.17 no.12
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• pp.963-968
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• 2009

Liquid crystal (LC; E7 and/or ML-0249)-embedded, poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-co-HFP)-based, polymer electrolytes were prepared for use in dye-sensitized solar cells (DSSCs). The electrolytes contained 1-methyl-3-propylimidazolium iodide (PMII), tetrabutylammonium iodide (TBAI), and iodine ($I_2$), which participate in the $I_3^-/I^-$ redox couple. The incorporation of photochemically stable PVdF-co-HFP in the DSSCs created a stable polymer electrolyte that resisted leakage and volatilization. DSSCs, with liquid crystal(LC)-embedded PVdF-co-HFP-based polymer electrolytes between the amphiphilic ruthenium dye N719 absorbed to the nanocrystalline $TiO_2$ photoanode and the Pt counter electrode, were fabricated. These DSSCs displayed enhanced redox couple reduction and reduced charge recombination in comparison to that fabricated from the conventional PVdF-co-HFP-based polymer electrolyte. The behavior of the polymer electrolyte was improved by the addition of optimized amounts of plasticizers, such as ethylene carbonate (EC) and propylene carbonate (PC). The significantly increased short-circuit current density ($J_{sc}$, $14.60\;mA/cm^2$) and open-circuit voltage ($V_{oc}$, 0.68 V) of these DSSCs led to a high power conversion efficiency (PCE) of 6.42% and a fill factor of 0.65 under a standard light intensity of $100\;mW/cm^2$ irradiation of AM 1.5 sunlight. A DSSC fabricated by using E7-embedded PVdF-co-HFP-based polymer electrolyte exhibited a maximum incident photon-to-current conversion efficiency (IPCE) of 50%.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.506-510
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• 2010

Electron recombinations in electrolyte solution reduce light-to-energy conversion efficiency at the nanoporous electrode surface of dye sensitized solar cells. In this study, we improved the conversion efficiency using an energy barrier at the nanoporous electrode surface to control the recombination process. The energy barrier was formed by coating nanoporous $TiO_2$ electrode with $Nb_2O_5$ material. We investigated the influence of energy barrier on the cell efficiency depending on the coating thickness. Nanoporous $TiO_2$ electrode was coated about 5 nm thickness by 12 times coatings, and so the coating layer was grown about 0.417 nm for every time. Enhancement of conversion efficiency from 2.55% to 4.25% was achieved at 0.834 nm coating thickness, and it was believed as the optimum thickness for minimizing the electron recombination process in our experimental system.

• Journal of Haehwa Medicine
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• v.12 no.1
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• pp.79-102
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• 2003

It has been believed that the human body can be effected by color, sound, smell, and taste - each of them is based on the original character. Out of these elements, the color can be a mediation that absorbs energy into human body and adapts it to the creatures whose life are definitely based on the solar energy. This thesis makes a study of the possibility of applying the color to the oriental medical science by researching the color psychology and therapy which are studied in the west medical science, the recognition and application of color developed from orientalism, and the opinion of color in the oriental medical science. Color therapy is one of the psychological treatment techniques that are able to recover and maintain the health with the rays of the sun rays and the color. The light and the color have its energy that may relax, harmonize, encourage, or excite a human being. This is because the wavelength and the vibration of each color will take effects to human body. The core energy of absorbing and distributing the color vibration is made in the 7 "chakras" in the body, which are the pith and marrow of bio-energy directly connected with the center of the nervous system. There are several methods in the color therapy - the treatment of solar ray, the color-bath, the water-therapy using color energy, the inducement of the solar energy into the body, the acupuncture, the therapy of crystal and jewel, and the self-suggestion dependent upon the color. The color therapy can help us to keep our balance by changing the emotion into the positive energy that will cure the disease with color. As a result, this method not only must be useful to cure physical disease, or develop into good health but also will be used in conforming itself to the mental disease. The color therapy mainly uses the eight colors, which are made by mixing Red, Yellow and Blue basic colors in the field. They are never used in the treatment, but they will go along with complementary colors. This rule is closely connected with the theory of yin and yang which lies at the root of oriental philosophy, and with the treatment principle of oriental medical science whose field is focused on the balancing the body mentally as well as physically. In the East, it is the Obangsaek - the color of blue, red, yellow, white, and black in the theory of yin and yang and the five elements that have been used in helping people having trouble with their health for a long time. In the view of the oriental medical science, these five colors attached the theory of five-elements have been very useful to the physiology, the pathology, or the diagnosis, and been applied to the medical treatment, combining themselves with a five-taste in medicinal herbs. Since the study of color and human physiology has been made in some different interest and fields these days, it goes to prove that the different function of color we couldn't have got before becomes very useful to the medical science. The color must be worth researching the diversity for applying itself to the oriental medical science.

• Korean Journal of Optics and Photonics
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• v.24 no.5
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• pp.213-216
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• 2013

This paper presents a combination of linear Fresnel lenses optimized for ${\times}25$ solar concentration. The combined lens consists of $5{\times}5$ linear Fresnel lenses. Each Fresnel lens is of $10{\times}10$ mm and optimized to tilt the incoming light onto a solar cell of the same size. All of the optimized Fresnel segments have the same pattern height of 35 ${\mu}m$, draft angle of $4^{\circ}$, and edge groove round of 1 ${\mu}m$ but with different facet angles varying from $14.1^{\circ}$ to $31.2^{\circ}$. The solar concentrating efficiency of the combination is shown to be over 80% and more robust than a conventional single ${\times}25$ circular Fresnel lens in terms of pointing misalignment and manufacturing errors. A sensitivity analysis finds that the edge groove round should be kept as small as machining allows since the concentrating efficiency drops ~5% per 1 ${\mu}m$ increase of the edge groove.

• Journal of Photoscience
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• v.9 no.2
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• pp.451-453
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• 2002

A new concept of "photo" -antisense method has been evaluated, where the inhibition of gene expression by the conventional antisense method is enhanced by photochemical binding between antisense oligonucleotides conjugated with photo-reactive compound and target mRNA or DNA. Fluorescein labeled oligodeoxyribonucleotides (F-DNA) was delivered to cell nuclei in the encapsulated form in multilamellar lecithin liposomes with neutral charge. F-DNA was previously shown to photo-bind to the complementary stranded DNA, and the delivery system using neutral liposome to be effective in normal human keratinocytes. In the present study, we used human kidney cancer G401.2/6TG.1 cell line to be advantageous in reproducible experiments. p53 was adopted as a target gene since antisense sequence information has been accumulated. The nuclear localization ofF-DNA was identified by comparing the fluorescence ofF-DNA with that of Hoechst 33258 under fluorescence microscope. After 7hr incubation to accumulate p53 protein induced by UV -B, p53 protein was quantified by Western blot. After 2hrs from F-DNA application, about 30% of cell population incorporated F-DNA in their nuclei with some morphological change possibly due to liposomal toxicity. Irradiation of visible light longer than 400nm from solar simulator at this time enhanced the inhibitory action of antisense F-DNA. The present results suggest that photo-antisense method is promising to control gene expression in time and space dependent manner. Further improvement of F-DNA delivery to cancer cells in the stability and toxicity is in progress. progress.