• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.1
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• pp.27-32
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• 2000

In this paper, ultrasonic wave in the thermoelastic regime was generated in a steel disk by illuminating a pulse laser (Q-switched Nd:YAG) on the surface of the sample and was detected on the other side by Michelson interferometer which was stabilized by feed back control. The experimentally detected displacement waveform of the ultrasonic wave showed good agreement with the theoretically expected one. Also it was shown that sound speeds of longitudinal and shear wave were similar to ones measured by pulse-echo method using a contact transducer. As an application of the noncontact ultrasonic measurement by using laser based ultrasonics, the sound speed in the sample was monitored while the sample was heated in a furnace, and the result showed that it decreased according to the increase of sample temperature.

• The Korean Journal of Zoology
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• v.28 no.4
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• pp.257-278
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• 1985

The effect of aromatic amino acids such as phenylalaine, tryptophan and tyrosine on somitogenesis at the early stage of chick embryo has been investigated morphologically using light and electron microscopy. Micrographs of aromatic amino acid injected chick embryo showed that an incomplete somite segmentation occurred and some decremental effect on the nervous system were observed. Somites were poorly developed and their size were variable. Electron micrograph of somatic cells from aromatic amino acid injected chick embryo showed that chromatins were coagulated, some of mitochondria were damaged, and nucleus were transformed considerably in some cases. The protein and nucleic acid levels and some enzyme activities of 15-day chick embryo which received the injection of 1mg of aromatic amino acid in 0.05 ml of saline 24 hours after the incubation were analyzed. Protein, DNA and RNA levels of the test group were not lowered significantly but the activities of enzymes for basic metabolism, such as lactate dehydrogenase, succinate dehydrogenase, malate dehydrogenase and glucose 6-phosphate dehydrogenase were considerably lowered as compared with those of control. From the present expeerimental results, it was tentatively suggested that the administration of amino acid might slow down the yolk granule degradation probably by feed back mechanism resulting in the disturbance of amino acid balance in the cell, which might give rise to impair normal metabolic pattern leading to abnormal somitogenesis to chick embryo at very early stage of development.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.415-420
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• 1999

A biochemical oxygen demand (BOD) sensor loaded with Candida sp. was designed and constructed for the quick measurement of the concentrations of biologically assimilable organic substances dissolved in water. The sensitivity of the sensor was higher for glucose, acetic acid, aspartic acid and glutamic acid than that for lactose, sucrose and lactic acid. The sensitivities of BOD sensors loaded with $Zn^{2+}$ tolerant and intact strains were almost identical while the sensitivity of sensor loaded with Cd$^{2+}$ tolerant strain was considerably lower. The sensitivities of the sensors loaded with intact or $Zn^{2+}$ tolerant strains did not change with the concentration of $Cd^{2+}$ in the aqueous solution while the sensitivity of the sensor loaded with $Cd^{2+}$ tolerant strain decreased slightly. The sensitivities of the sensors loaded with intact strain, $Zn^{2+}$ or $Cd^{2+}$ tolerant strains were not affected by the concentration of $Zn^{2+}$ in the aqueous solution.n.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.3
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• pp.215-222
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• 1995

Nb doped strontium titanate single crystals were grown by the floating zone method. The doping amount of $Nb_2O_5$ was 0.2 wt %. Those crystals were grown in air and N z atmosphere and the growth rate was 5 mmlhr and rotation speed of upper and lower shaft was 30 rpm. The shapes of melt - feed rod interface depending on sintering temperatures were observed. In air atmosphere, the flow rate of air was 1.5 ${\ell}/min$ and in $N_2$ atmosphere, that of $N_2$ gas was 0.5 ${\ell}/min$. As grown crystals were analyseQ by XRD, Laue back - reflection and chemical etching. After annealing in $N_2$ atmosphere, resistivities of crystals were measured and the activation energies of each samples were calculated.

• International Journal of Concrete Structures and Materials
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• v.7 no.3
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• pp.225-238
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• 2013

In this study, a two-layer feed-forward neural network was constructed and applied to determine a mapping associating mix design and testing factors of cement-nano silica (NS)-rice husk ash ternary blended concrete samples with their performance in conductance to the water absorption properties. To generate data for the neural network model (NNM), a total of 174 field cores from 58 different mixes at three ages were tested in the laboratory for each of percentage, velocity and coefficient of water absorption and mix volumetric properties. The significant factors (six items) that affect the permeability properties of ternary blended concrete were identified by experimental studies which were: (1) percentage of cement; (2) content of rice husk ash; (3) percentage of 15 nm of $SiO_2$ particles; (4) content of NS particles with average size of 80 nm; (5) effect of curing medium and (6) curing time. The mentioned significant factors were then used to define the domain of a neural network which was trained based on the Levenberg-Marquardt back propagation algorithm using Matlab software. Excellent agreement was observed between simulation and laboratory data. It is believed that the novel developed NNM with three outputs will be a useful tool in the study of the permeability properties of ternary blended concrete and its maintenance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1316-1324
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• 2009

In this paper, cross-aperture coupled microstrip circular polarization antenna is proposed for 5.8 GHz WLAN(Wireless Local Area Network). A single antenna consists of square patch and slots are located in series feed line with $\lambda_g$/4 phase different which make current direction maximum and minimum repeatedly to generate RHCP(Right Handed Circularly Polarization). We are proposed new structure that removed the section which intersected at a right angle and were composed to four separated slots. The proposed cross slots reduce back lobe of radiation pattern and improve antenna gain. Impedance bandwidth of the manufactured $2\times2$ array antenna is from 5.67 to 5.95 GHz and the maximum radiation gain is 10.59 dBi.

• Environmental Mutagens and Carcinogens
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• v.18 no.1
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• pp.22-25
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• 1998

Anticarcinogenic activity of astaxanthin-containing egg yolks (designate AEY) was investigated for 7,12-dimethylbenz[a]anthracene (DMBA)-induced two stage mouse epidermal carcinogenesis. Female ICR mouse (6-7 weeks of age) were house in a humidity-and-temperature-controlled facility and subjected to feed and water ad libitum. AEY (10 mg/0.2 ml acetone) was painted on the back of mice 7 days, 3 days and 5 min before DMBA treatment (50 nmole/0.2 ml acetone). One week later after DMBA treatment, 6 ${\mu}g$ tetradecanoyl 12-phorbol 13-O-acetate (TPA) dissolved in 0.2 ml acetone was applied on the mouse twice weekly over a period of 22 weeks. No sample was given to control mice. Control egg yolk (CEY) and astaxanthin-containing oil (designate AO) from Phaffia rhodozyma were used as positive controls. Mouse treated with AEY exhibited 10 tumors per mouse whereas control mouse exhibited 15 tumors per mouse, the fact that 33% reduction of tumor per mouse by AEY treatment. Tumor incidence was also reduced to 15% by AEY treatment when compared to that of control group. Such effects were also seen in CEY and AO treatment groups, but leaser extent. AO gave reduction of food intake and body weights relative to those of AEY and CEY, indicating toxicity of AO. These results suggest that AEY exhibits anticarcinogenic activity for DMBA-induced mouse epidermal carcinogenesis.

• Korean Institute of Interior Design Journal
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• v.20 no.3
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• pp.182-189
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• 2011

This research suggests a way of hygienic space planing of the customer space in the university student restaurant of E University in Seoul. For this study. the behavior observation in the restaurant was conducted in order to analyze the sequence of customer behavior related space planing applying HACCP (Hazard Analysis And Critical Control Point). Also the survey was conducted to analyze opinions of customers about hygiene of the space. The results of the analyses of the observation and the survey were similar in terms of hygiene. In conclusion, for hygienic space planing of the customer space in restaurant, the space circulation should be planned according to the hygienic sequence of customer behavior. The spaces in restaurant should be divided into two areas: the clean area and the contaminated area to prevent cross-contamination. The clean area, such as spaces preparing dishes and food including water and table hall where customers eat, should be separated from the contaminated area such as the spaces where waste is handled and where dirty dishes are kept. In order to prevent cross-contamination, hygiene facility to remove contamination should be located before going to the clean area. More specifically, the hygiene facility should be located between a cash counter and a space preparing dishes so that customers can wash their hands before they touch dishes. Space arrangement with feed-back process to check the possible points of cross-contamination and correct space arrangement until the possibility of cross-contamination is removed in the restaurant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3391-3397
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• 2011

These excavators have been widely used due to their flexibility in handing various tasks via simple changes of their attachments. Since the performance of manually-operated excavators heavily depend on the operators' skill level, there is a strong need for developing automatic excavators in the industry. In order to achieve such goals, exiting approaches have studied direct modification of existing hydraulic systems in the excavator for feed back control of each link. This paper presents a miniaturized automatic excavator that can be used for the development and demonstration of advanced control algorithm for excavators under a safer environment with reduced cost. Two PCs were installed and connected to the excavator through wireless communications for its control and monitoring. Tracking control of each link using a time varying sliding mode controller was performed through experiments on the developed system to demonstrate its ability.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.211-216
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• 2015

Large hydraulic excavator weighted 90 tons used the several pumps installed in parallel to use the hydraulic pump driving gearbox to improve fuel consumption by improving the energy efficiency of the hydraulic system. Gearbox connected to hydraulic pump supply the mechanical output to the high pressure and low pressure pump to be supplied by torque and rotation, which are the mechanical power, through a input shaft connected to large size engine of the excavator. So, gearbox connected to hydraulic pump is same as main artery in the human body and is required long life because it operates the hydraulic pump continuously during operating the engine. This study had used oil contamination analysis method to check the wear characteristics of the gearbox and frequency response characteristic analysis method to check the failure of the teeth failures of gearbox, while the test equipment adopted by the electrical feedback method to reduce the energy consumption was operating for the life assessment, in which the required power was 600 kW input power.