• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.10
• /
• pp.1129-1135
• /
• 2005

In this study. the applicability of a rotating reactor for the oxidative removal of aqueous humic substances extracted from the Han River in Seoul, Korea was investigated. As air blowing for proper mixing of $TiO_2$ photocatalyst could inhibit UV-irradiation between a UV lamp and photocatalyst by air bubbles, a rotating reactor with some baffles was used for better UV-irradiation effect in this study. Han River humic substances are different from the other commercial humic substances(e.g., from Aldrich and International Humic Substance Society). Their characteristics were investigated with structural and spectroscopic analyses using FT-IR(Fourier transform-infrared), and $^{13}C$-NMR (nuclear magnetic resonance). The humic substances were extracted by XAD-7HP and treated with $TiO_2$-coated hollow beads under UV-A and UV-C irradiation in order to solve problems of separation and recovery of photocatalyst after reaction. At approximately 5 mg/L of initial TOC concentration, pH 3 and $2.0\;g-TiO_2/L$ dose, photocatalytic oxidation of Han River humic substances showed the optimum removal efficiency. Also, UV-C and UV-A lamps showed similar TOC removal efficiency. However, under UV-C irradiation, Han River humic substances were degraded to smaller compounds and increased the proportion of low molecular weight fractions compared to UV-A.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.38 no.2
• /
• pp.139-145
• /
• 2012

There is a unique type of fatty acid in the hair surface. 18-methyleicosanoic acid (18-MEA) is an unusual anteiso fatty acid covalently linked to the outermost surface of hair cuticle. A layer of 18-MEA is located in the upper ${\beta}$-layer of the CMC that is responsible for the low surface energy and low friction resistance of the hair's outer surface. The high mobility of 18-MEA molecule facilitates spreading of extraneous lipid by decreasing interfacial shear strength. In this study, we introduced N-hydroxyl succinimidyl ester functional group to the one end of C10 - 40 isoalkyl acid for regenerating hair surface with covalently bound fatty acid layer. The re-hydrophobicization of hair surface has been investigated by contact angle measurement. The inner moisture content of hair at different levels of humidity (40, 55, 70 %RH) was measured by electric moisture analyzer. Treatment with Hydroxysuccinimidyl C10 - 40 Isoalkyl Acidate (HCIA) was supposed to make hair surface smoother by filling the cracks between cuticles with covalently bound fatty acid monomolecular layer like cuticle glue. This glue effect was also confirmed with line profile of AFM images. Therefore, the moisture and structural components of inner hair were not easily flown out and the optimum moisture content could be kept constantly though the outside humidity level was changed. The lateral force microscopy (LFM) by using atomic force microscope showed that the friction force of hair surface treated with HCIA was decreased. It also showed the constantly sustained friction value even after shampooing repeated 15 times.

• International Journal of Highway Engineering
• /
• v.13 no.4
• /
• pp.81-91
• /
• 2011

This study was conducted to evaluate the necessity of the anchor lug system in continuously reinforced concrete pavement(CRCP) by comparing longitudinal displacements of CRCPs with and without anchor lugs, and to investigate the effect of horizontal cracking on CRCP performance by measuring the vertical displacements. The measurements before and after the anchor lug section was separated were conducted for 12 days in June, and for 14 days in August after the abrupt displacements according to cutting disappeared, respectively. This short term measurement results showed that when anchor lugs were installed, a daily displacement variation at any location was less than 0.1mm; therefore, longitudinal movements were negligibly small. When there were no anchor lugs, longitudinal displacements mainly occurred near the free end and the displacement variation was small; therefore, an expansion joint system seems to be employed at a CRCP terminus without installing anchor lugs. However, further studies are needed to verify the terminus behavior due to annual temperature changes. The horizontal crack width variation was ignorable and did not affect the vertical displacement of the slab. Therefore, the horizontal crack did not delaminate the slab and did not seem to reduce the structural capacity and performance of CRCP.

• Korean Security Journal
• /
• no.34
• /
• pp.57-88
• /
• 2013

The study aims at identifying, through structure model, the relationship characteristics between a private security company and its service customer as well as the relationship between the service quality and the consumer behavior, thereby providing the practical services that may attract new customers and maintain the existing customers in the competition to survive in the same industry and also may raise the loyal customer base, providing academic fundamental data to set up aggressive relationship marketing strategies. To achieve such purposes above, the research was conducted with 229 subjects, the users of a private security company's service as the employees of the stores located in Cheonan area, using the convenience sampling. The data was treated, using the statistics program, SPSS Windows 18.0 Version for frequency analysis and reliability analysis. Additionally, the confirmative factor analysis and covariance structural analysis were made, using AMOS 18.0 Version. Through the data analysis following the research methods above, the conclusion was acquired as follows: First, the relationship characteristics of a private security company makes influence on service quality. Second, the service quality of a private security company makes influence on consumer behavior. Third, the relationship characteristics of a private security company makes influence on consumer behavior. Fourth, the service quality makes an influence as the mediate effect between the private security company's relationship characteristics and consumer behavior.

• Korean Journal of Materials Research
• /
• v.30 no.4
• /
• pp.204-210
• /
• 2020

ZnO thin films are of considerable interest because they can be customized by various coating technologies to have high electrical conductivity and high visible light transmittance. Therefore, ZnO thin films can be applied to various optoelectronic device applications such as transparent conducting thin films, solar cells and displays. In this study, ZnO rod and thin films are fabricated using aqueous chemical bath deposition (CBD), which is a low-cost method at low temperatures, and environmentally friendly. To investigate the structural, electrical and optical properties of ZnO for the presence of citrate ion, which can significantly affect crystal form of ZnO, various amounts of the citrate ion are added to the aqueous CBD ZnO reaction bath. As a result, ZnO crystals show a nanorod form without citrate, but a continuous thin film when citrate is above a certain concentration. In addition, as the citrate concentration increases, the electrical conductivity of the ZnO thin films increases, and is almost unchanged above a certain citrate concentration. Cu(In,Ga)Se₂ (CIGS) solar cell substrates are used to evaluate whether aqueous CBD ZnO thin films can be applicable to real devices. The performance of aqueous CBD ZnO thin films shows performance similar to that of a sputter-deposited ZnO:Al thin film as top transparent electrodes of CIGS solar cells.

• Journal of Korean Society of Steel Construction
• /
• v.29 no.1
• /
• pp.81-88
• /
• 2017

Residual stress is defined as stress that already exists on a structural member from the effects of welding and plastic deformation before the application of loading. Due to such residual stress, welded H-section compression members under centroidal compression load can undergo buckling and failure for strength values smaller than the predicted buckling load and specified compressive strength. Therefore, this study was carried out to evaluate the effect of residual stress from welding on the determination of the buckling load and specified compressive strength of the H-section compression member according to the column length variation. A three-dimensional nonlinear finite element analysis was performed for the H-section compression member where the welded joint was fillet welded by applying heat inputs of 3.1kJ/mm and 3.6kJ/mm using the SAW welding method.

• Korean Journal of Materials Research
• /
• v.14 no.10
• /
• pp.731-736
• /
• 2004

Herein, we report on the co-firing of a low-K wiring substrate and a middle-K functional substrate in LTCC. Firstly, we researched the sintering behavior and dielectric properties of the low-k wiring substrate comprised by alumina and glass frit with ${\varepsilon}_r$, of $\sim7$ and the middle-k functional substrate comprised by $Ba_{5}Nb_{4}O_{15}$ and glass frit with ${\varepsilon}_r$, of $20\sim30$. The warpage and delamination between the hetero layers of the low-K and the middle-K composition were also studied. In particular, physical matching of the hetero layers could be possible by adjusting of the sintering properties of the composition. We observed that an introduction of the glass frit to the low- and middle-K substrate gives rise to a minimization of an effect given by separation of the hetero layers, and modification of the fraction of the glass frit accompanied by a variation of the composition could control the sintering behavior and its beginning temperature. In the case of co-firing of the L03 as the low-K wiring substrate composition and the M03 as the middle-K functional substrate composition at $875^{\circ}C$, we could fabricate a desirable structure of hetero layers without any kinds of structural defects such as separation, warpage, delamination, pore trap, etc. We suppose that the co-firing techniques described in this study would provide a helpful method to fabricate a LTCC multi-functional for the next generation.

• Korean Journal of Materials Research
• /
• v.11 no.8
• /
• pp.661-665
• /
• 2001

The mechanical alloying (MA) effect in $\sigma$-VFe intermetallic compound was studied by neutron and X-ray diffraction. The structure of MA $\sigma$-VFe powders were characterized by the X- ray diffraction with Cu- $K\alpha$ radiation and neutron diffraction with monochromatic neutrons of $1.835\AA$ using a high resolution powder diffractometer (HRPD). Mechanical alloying of $\sigma$-VFe compound gives rise to a dramatic structural change. After 60 hours of MA, the Fe-Fe distribution of the $\sigma$- phase VFe tetragonal structure with 30 atoms in a unit cell is found to change into that of the $\sigma$-(V,Fe) solid solution with bcc structure, which is a stable phase at elevated temperature above $1200^{\circ}C$. A comparison of X-ray diffraction data for the $\alpha$-phase has been also made with the corresponding neutron diffraction data. The (101) and (111) diffraction peaks of the $\sigma$-phase was clearly observed only in neutron diffraction pattern, which is believed to be a characteristic feature due to the chemical atomic ordering of $\sigma$- VFe phase.

• Journal of Acupuncture Research
• /
• v.25 no.1
• /
• pp.155-167
• /
• 2008

Objectives : The objective of this study was to observe the positive effects of acupuncture and bee-venom acupuncture treatment on lumbar hypolordosis. Methods : Acupuncture and bee-venom acupuncture were performed twice a week for 30 days to treat patients with low back pain patients showing a Cobb's angle [L1-S1] of less than $35^{\circ}$(treatment group=20, control group=13). Lumbar lordosis(Cobb's angle [L1-S1], Centroid angle [L1-S1]) was measured using an L-spine Lat. X-ray before and after treatment. Pain scales(VAS scale, ODI) were also was measured before and after treatment. SPSS 12K for Windows was used for statistical analysis of the results. Results : 1. VAS and ODI decreased significantly in the treatment group. 2. Lumbar lordosis, presented by Cobb's angle, increased significantly from $25.00{\pm}7.06^{\circ}$ to $30.95{\pm}10.02^{\circ}$ (p = 0.006). The increase of Cobb's angle in the treatment group $5.95{\pm}8.60^{\circ}$, and that of the control group was $-3.08{\pm}8.41^{\circ}$(p = 0.006). The increase of the Centroid angle of the treatment group was $3.85{\pm}8.83^{\circ}$, and that of the control group was $-2.92{\pm}7.63^{\circ}$(p=0.031). 3. Cobb's angle and Vas scale showed a significant correlation coefficient of -0.250(p=0.043). Increase of Cobb's angle and decrease of Vas scale showed a significant correlation coefficient of 0.420(p=0.015). Conclusions : Acupuncture and bee-venom acupuncture were verified to have a positive effect on pain alleviation of lumbar lordosis decreased patients while also affecting lumbar lordosis to be increased as a result of structural changes. It was also shown that lumbar hypolordosis has significant correlation with pain.

• Journal of the Korean Magnetics Society
• /
• v.4 no.3
• /
• pp.263-271
• /
• 1994

We have produced $Co_{1-x}Pt_{x}(X\;=\;0.53\;and\;0.75)$ alloy films by DC magnetron sputtering at various substrate temperatures and sputtering pressures. Sputter-deposited Co-Pt alloy films showed a strong (111) texture, and the degree of (111) texture of the as-deposited film was found to depend on the substrate temperature and Ar pressure. However, we observed that the degree of (111) texture did not affect the magnetic properties. In addition, we have investigated the effect of heat-treatment on magnetic properties of these films. While the magnetic properties of the $Co_{0.25}Pt_{0.75}$ alloy films showed no noticeable changes, the coercivities and the squarenesses of the $Co_{0.47}Pt_{0.53}$ alloy films were drastically increased by annealing. Structural analysis using transmission electron microscopy(TEM) and x-ray diffractornetry(XRD) revealed that $CoPt(L1_{0})$ and $CoPt_3(L1_{2})$ ordered phases, respectively, were formed, each with a strong (111) texture. By comparing the magnetic properties between $CoPt(L1_{0})$ and $CoPt_3(L1_{2})$ ordered phases in relation to the atomic arrangements in a unit cell, we conclude that the magnetic anisotropy in the Co-Pt alloy system depends mainly on the atomic arrangements of Co and Pt.