• Journal of the Korean Magnetics Society
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• v.18 no.3
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• pp.120-125
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• 2008

In this study, NiCoZn ferrites with the variation of sintering temperature and chemical composition were prepared by the coprecipitation. Microstructures Crystal structure of NiCoZn ferrites were analyzed by XRD and their electric magnetic characteristics were analyzed by LCR meter and their morphology observed by SEM. We identified that these powders have a typical NiCoZn spinel structure and nanoparticles average size of 40 nm. The impurity, the initial permeability and the Q factor value are the lowest of sintered NiCoZn ferrite at $1250^{\circ}C$. Also, we measured S-parameter for $(Ni_{0.4}Co_{0.1}Zn_{0.5})Fe_2O_4$ which showed a maximum reflection loss of -3.1 dB at 6 GHz for the 2 mm thick sample. From this result, we found that the NiCoZn ferrite can be used in ferrite microwave-absorbing application at a higher frequency region (> 6 GHz).

• Journal of dental hygiene science
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• v.18 no.4
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• pp.265-270
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• 2018

The purpose of this study was to investigate the chemical properties of some commercially available mouthwashes and to ascertain whether the mouthwashes accelerated mineral loss in dental enamel. Five commercially available mouthwashes were selected from the three largest malls in Korea: Perio Total 7 Aqua Cool Mint Strong $Fresh^{TM}$ (PS; LG Household & Health Care Ltd.), Garglin $Original^{TM}$ (Dong-A Pharmaceutical Co., Ltd.), Garglin $Zero^{TM}$ (Dong-A Pharmaceutical Co., Ltd.), Listerine Naturals $Citrus^{TM}$ (LC; IDS Manufacturing Ltd.), and Listerine Cool $Mint^{TM}$ (LM; IDS Manufacturing Ltd.). The composition, pH, and titratable acidity of the mouthwashes were investigated. Six bovine teeth specimens were prepared for each mouthwash group. Each of the six specimens was individually immersed in 30 ml aliquots of mouthwash for 1 minute, 30 minutes, 90 minutes, and 120 minutes, and the samples were placed in a $36.5^{\circ}C$ stirred incubator. The degree of mineral loss (${\Delta}F$) of the tooth surface area exposed to mouthwash, compared with normal teeth, was analyzed by quantitative light-induced fluorescence-digital. The difference in ${\Delta}F$ among mouthwash groups was examined by the Kruskal-Wallis H test (${\alpha}=0.05$). The contents of mouthwashes differed between Listerine and other products, and the pH ranged from 4.09 to 6.75. The titratable acidity of PS was the lowest at 0.63 ml and highest at 9.25 ml for LM. Minor mineral loss was observed when dental specimens were immersed in the Listerine products (LC and LM) for more than 90 minutes, but the degree of mineral loss for Listerine products was not statistically significantly different from that for groups without mineral loss. In conclusion, all five commercially available mouthwashes showed no harmful effects on tooth enamel.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.1
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• pp.35-40
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• 2016

The maxillary defects lead to anatomical and functional deformity of the maxillofacial region. As far as functions are concerned, such defects can produce difficulty in speech, mastication, and deglutition. Obturator prostheses play a very important role in functional recovery for post-maxillectomy patients. To achieve rigidity of the obturator, appropriate retention should be given, and the weight of the prosthesis be reduced. There are two types of hollow bulb obturator: open and closed. A closed type has many advantages. Nevertheless, some problems, including complexity of fabrication and water leakage into the bulb, have the closed hollow obturator not be widely used. The one-step polymerization technique described in this case overcomes the shortcomings by easily constructing a small hollow bulb with two thermoplastic resin sheets.

• Journal of Auto-vehicle Safety Association
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• v.7 no.3
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• pp.7-13
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• 2015

Occupant protection performance in frontal crashes has been developed and assessed for mainly front seat occupants over many years, and in recent years protection of rear seat occupants has also been extensively discussed. Unlike the front seats, the rear seats are often occupied by children seated in rear-facing or forward - facing child restraint systems, or booster seats. In the ENCAP, child occupant protection assessments using 18-month-old(P1.5) and 3-year-old(P3) test dummies in the rear seat have already been changed to new type of 18-month-old (Q1.5)and 3-year-old(Q3) test dummies. In addition, ENCAP are scheduled with the development and introduction of test dummies of 6-year-old (Q6) and 10.5-year-old children(Q10) starting 2016. In KNCAP, Q6 and Q10 child dummies will be introduced in 2017 as well. Automobile manufacturers need to develop safety performance for new child dummies closely. In this paper, we focused on Q6 and Q10 child dummies sitting in child restraint system. Offset frontal crash tests were conducted using two types of test dummies, Q6 and Q10 child dummies, positioned in the rear seat. Q6 and Q10 were used to compare dummy kinematics in rear seating positions between Q6 behind the driver's seat and Q10 behind the front passenger's seat. The full vehicle sled test results of both dummies were conducted with different restraint systems. It showed that several injury and image data was collected as the result of the full vehicle sled test. Based on the results of these investigations, this paper describes which factor is most important and combination is the best performance when evaluating rear seat occupant protection for Q6 and Q10 child dummies.

• Proceedings of the Ginseng society Conference
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• 1988.08a
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• pp.81-86
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• 1988

The effect of three polyacetylene compounds. panaxydol. panaxynol and panaxytriol isolated from Korean ginseng on $CCI_4-induced$ lipid peroxidation in vitro and in vivo hepatic microsomal lipid peroxidation were investigated. Lipid peroxide levels both in serum and liver and serum enzyme (GOT. GPT. LDH) activities of normal or $CCI_4-treated$ mice and rats were also determined after administration of polyacetylenes. Hepatic microsomal cytochrome P-450 content and activities of aniline hydroxylase and aminopyrine demethylase were measured after treatment of polyacetylenes with or without carbon tetrachloride. As results. treatment with polyacetylenes to control mice did not influence the levels of lipid peroxides and serum enzyme activities while panaxynol did. Panaxynol itself inhibited liver lipid peroxidation in normal mice. Polyacetylene compounds protected hepatic lipid peroxidation and lowered serum lipid peroxide levels induced by $CCI_4$ Polyacetylenes prevented leakage of LDH to serum but elevated GOT and GPT levels caused by $CCI_4$ were not changed by polyacetylene pretreatment. $CCI_4$ caused losses in the content of cytochrome P-450 and activities of aniline hydroxylase and aminopyrine demethylase. When polyacetylenes were treated without $CCI_4$ panaxydol and panaxynol induced aniline hydroxylase and all three polyacetylenes induced aminopyrine demethylase. Cytochrome P-450 contents were not affected by polyacetylenes. In vitro hepatic microsomal lipid peroxidation was inhibited by polyacetylenes and $DL-{\alpha}-tocopherol$ in a concentration-dependent manner.

• Korean Journal of Construction Engineering and Management
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• v.14 no.3
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• pp.42-52
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• 2013

The aim of this study is to present a prediction model of construction cost for a bridge that has a high reliability using historical data from the planning phase based on a CBR (Case-Based Reasoning) method in order to overcome limitations of existing construction cost prediction methods, which is linearly estimated. To do this, a reasoning model of bridge construction cost by a spreadsheet template was suggested using complexly both CBR and GA (Genetic Algorithm). Besides, this study performed a case study to verify the suggested cost reasoning model for bridge construction projects. Measuring efficiency for a result of the case study was 8.69% on average. Since accuracy of the suggested prediction cost is relatively high compared to the other analysis methods for a prediction of construction cost, reliability of the suggested model was secured. In the case that information for detailed specifications of each bridge type in an initial design phase is difficult to be collected, the suggested model is able to predict the bridge construction cost within the minimized measuring efficiency with only the representative specifications for bridges as an improved correction method. Therefore, it is expected that the model will be used to estimate a reasonable construction cost for a bridge project.

• Journal of the Korean Electrochemical Society
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• v.7 no.1
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• pp.38-43
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• 2004

Porous carbon aerogel-silica gel composite materials were used as the electrodes of capacitive deionization(CDI) process, which were prepared by a paste rolling method. The electrochemical parameters such at current values, coulombs af a function of cycle, and CDI efficiencies were investigated for 10th and 100th cycles in 1,000ppm NaCl solution. Carbon aerogel-silica gel composite electrodes showed good wet-ability and higher mechanical strengths even under the NaCl solutions as well. In our experimented runs, all of the composite electrodes also are showed good cycle-ability without destroy of active material during cycles and decreased manufacturing times by $50\%$. Conclusively, the adding of silica gel powder to carbon aerogel leads to the effective performance of CDI process due to effective utilization of active materials by increasing the wet-ability and mechanical hardness.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.4
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• pp.1-7
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• 1999

We developed Fabrication process of embedded passive components in MCM-D substrate. The proposed MCM-D substrate is based on Cu/photosensitive BCB multilayer. The substrate used is Si wafer and Ti/cu metallization is used to form the interconnect layer. Interconnect layers are formed with 1000$\AA$ Ti/3000$\AA$ Cu by sputtering method and 3$\mu\textrm{m}$ Cu by electrical plating method. In order to form the vias in photosensitive BCB layer, the process of BCB and plasma etch using $C_2F_6$ gas were evaluated. The MCM-D substrate is composed of 5 dielectric layers and 4 interconnect layers. Embedded resistors are made with NiCr and implemented on the $2^{nd}$ dielectric layer. The sheet resistance of NiCr is controlled to be about 21 $\Omega$/sq at the thickness of 600$\AA$. The multi-turn sprial inductors are designed in coplanar fashion on the $4^{th}$ interconnect layer with an underpass from the center to outside using the lower $3^{rd}$ interconnect layer. Capacitors are designed and realized between $1^{st}$ interconnect layer and $2^{nd}$ interconnect layer. An important issue in capacitor is the accurate determination of the dielectric thickness. We use the 900$\AA$ thickness of PECVD silicon nitride film as dielectric. Capacitance per unit area is about 88nF/$\textrm {cm}^2$at the thickness of 900$\AA$. The advantage of this integration process is the compatibility with the conventional semiconductor process due to low temperature PECVD silicon nitride process and thermal evaporation NiCr process.

• Journal of the Korea Institute of Building Construction
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• v.16 no.1
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• pp.67-76
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• 2016

Concrete exposed to severely low temperature below $-20^{\circ}C$ should be provided with proper heat supplying curing to protect the concrete from early frost damage at the time of pouring.meanwhile, so far, effective heat curingmethods of the concrete under severely low temperature are not well established in Korea. For this reason, the objective of this paper is to provide effective heat curingmethod of concrete exposed to severely low temperature to protect early frost damage by varying the combination of heat curingmaterial combinations. Temperature history,maturity development and core strength results are investigated. Fourmock-up specimens simulating slab, wall and column were prepared and heat insulation, heat supplying and both were applied. Test results indicate that the combination of quadruple layer bubble sheet(4BS) and embedding of heating cable has desirable performance for a slab, and heat supplying curing inside heat enclosure and heat generationmat also shows desirable performance for a wall, and for a column, use of EPS heat insulation has proper performance against early frost damage, which reaches $45^{\circ}D{\cdot}D$ and helps the concretemaintain above $0^{\circ}C$ within 3 days. Themethodsmentioned above are believed to be optimum protection from early frost damage of the concrete under $-20^{\circ}C$.

• Journal of the Korean association of regional geographers
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• v.17 no.5
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• pp.600-616
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• 2011

Since the Shimane Prefecture government in Japan enacted "Takeshima Day" in March 2005, it has held commemorative ceremonies with Japanese politicians present each year on February 22. Japan has marked Dokdo as its territory in elementary and middle high school textbooks, and the number of such references has been increasing in recent years. Shimane Prefecture, which is the area nearest to Dokdo is strengthening Dokdo education in its geography classes at elementary and middle schools as part of regional studies. The study and education on Dokdo was begun by social studies teachers in the Oki Islands in Shimane Prefecture, but now extends throughout the prefecture. The auxiliary educational materials regarding Dokdo produced in Shimane Prefecture include teaching guidelines for teachers, worksheets for students, CDs containing statistics and picture files, and two kinds of DVD movie clips for each grade. In particular, schools teach the damage to the Japanese fishery industry caused by Korea's illegal occupation of Dokdo. This will likely form anti-Korean sentiments among Japanese students. It is hoped that Korean and Japanese scholars will work together to develop Dokdo auxiliary textbooks in order to improve the correct historical understanding of Dokdo.