• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.6
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• pp.34-41
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• 1984

MOEN/MO double layer which is to be used It)r the RMOS (refractory metal oxide semiconductor) gate material has been fabricated by means of low temperature reactive sputtering in N2 and Ar mixture. Good Mo2N film was obtained in the volumetric mixture of Ar:N2=95:5. The sheet resistance of the fabricated Mo7N film was about 1.20 - 1.28 ohms/square, which is about an order of magnitude lower than that of polysilicon film, and this would enable to improve the operational speed of devices fabricated with this material. When PSG (phosphorus silicate glass) was used as impurity diffusion source for the source and drain of the RMOSFET in the N2 atmosphere at about 110$0^{\circ}C$, the Mo2N was reduced to Mo resulting in much smaller sheet resistance of about 0.38 ohm/square. The threshold voltage of the RMOSFET fabricated in our experiment was - 1.5 V, and both depletion and enhancement mode RMOSFETs could be obtained.

• Journal of the Korean Society of Safety
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• v.28 no.4
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• pp.38-42
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• 2013

This study performed the quantitative distribution analysis of created voids to an insulator when applying general flame and DC short-circuit current to 2.5 $mm^2$ HIV (600 V Grade Heat-Resistant Polyvinyl Chloride Insulated Wires). The diameter of cross-section of HIV normal product and the radius of conductor were measured to be 3.3 mm and 1.8 mm. The exterior of HIV exposed to general flame showed severe carbonization and its interior exhibited voids created by dechlorination reaction. This study observed the characteristics that, when the shortcircuit current applied for 2 seconds from a DC 12 V lead battery, the conductor and neighboring insulator were melted, causing the insulator adhering to the conductor. On average, 87 voids were created on 10 mm of the HIV. The average diameter of voids was 0.25 mm. In addition, it was found that, when the short-circuit current applied for 4 seconds, the interior of insulator in contact with conductor severely carbonized and showed exfoliation phenomenon. On average, 47 voids were created, with more voids at the bottom. The average diameter of voids was 0.20 mm. When the short-circuit current for 6 seconds, most parts of upper part of conductor was carbonized, 20 voids were created. The average diameter of voids was measured to be 0.24 mm. It could be seen that the created voids received little influence by the type of energy source and the number of created voids was reduced as the energy supply time increased.

• Journal of Advanced Navigation Technology
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• v.12 no.6
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• pp.604-610
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• 2008

A 2.4 GHz CMOS RF front-end using for ZigBee application is described The front-end consists of a low noise amplifier and a down-mixer and uses a 2 MHz IF frequency. A common source with resistive feedback and an inductive degeneration are adopted for a low noise amplifier, and a 20 dB gain control step is digitally controlled. A passive mixer for low current consumption is employed. The RF front-end is implemented in 0.18 ${\mu}m$IP6M CMOS process. The measured performance is 4.44 dB NF and -6.5 dBm IIP3 while consuming 3.28 mA current from a 1.8 V supply.

• Journal of the Korean Society of Radiology
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• v.4 no.2
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• pp.31-35
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• 2010

In this study, we surveyed students recognition of the base units and radiation related units among international standard units, and determined the necessity of unit education. The survey was conducted using a questionnaire composed of 18 questions, and in the survey, students at the Radiology Department were asked about recognition and education. According to the results of the survey, around 44% of the students answered wrongly on base unit kV, and around 28% answered wrongly on km. Particularly with regard to the relation between units and numbers, around 57% of the students chose wrong answers. As to prefix mega and giga, respectively, 22% and 20% of the students chose wrong answers. To the question on radiation related unit Sv, around 30% gave wrong answers. Recognition of radiation related units was higher in senior students. To the question of whether to have received special education on units, over 50% of the students replied negatively. These results suggest the necessity of education on international standard units.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.271-279
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• 2016

This study examines the properties of high-fluidity concrete after adding copper slag as a mineral admixture. For this purpose, the replacement ratio of cement to copper slag was varied to 0, 10, 20, 30, 40, and 50%. A slump flow test, reach time slump flow of 500 mm, and a U-Box and O-lot test were conducted on the fresh concrete. The compressive strength of the hardened concrete was determined at 3, 7, 14 and 28 days. According to the test results, the workability, compaction, and compressive strength of the high-fluidity concrete increased when replacing 30% of the cement with copper slag. These parameters decreased for all material ages with more than 30% copper slag, which was the optimal mixture ratio.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.3
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• pp.1-6
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• 2014

We measured color rendering index(CRI) of a LED lamp for lighting for aging-time. We chose bulb type white LED lamp six samples and halogen lamp one sample and applied 220V, 60Hz to all the samples for 1,000hours at ordinary temperature. The CRI was measured every 20hours and the CRI change of the LED lamp was compared with the halogen lamp's CRI change. As time goes, efficiency of the halogen lamp decreased and the CRI maintained uniformly. The other hand, efficiency of the LED lamp decreased but the CRI increased. The CRI of the LED lamp has been stabilized since 600hours. The CRI change of the LED lamp was analyzed with a spectrum, color coordinate and color temperature.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.4
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• pp.1024-1030
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• 2016

This study gives the vertical motion analysis due to changes in Submerged shape of Multi-Purpose Small Floating Body in irregular waves using the commercial code(MAXSURF v.20) based on the Panel method. To verify the commercial code prior to the analysis, we guarantees the reliability of this paper's results using the commercial code by comparing with the results of experimental results on Catamaran. The anlysis conditions are ITTC wave spectrum, each encounter angle. Finally, we analyze the result of ship's response spectra for vertical motions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.4
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• pp.16-20
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• 2014

To prevent any accident in electric power utilities, many researches for inspection and diagnosis deteriorations occurring by corona discharges have been continuously studying. Inspection and diagnosis of electric power utility is very important to prevent an accident. This paper studies a measurement of ultra-violet(UV) ray of corona discharges on polymer insulators using an UV sensor array with an optic lens. The detection of an UV signal begins at 60kV, which is about 37.5% of the breakdown voltage of the polymer insulator and the stronger the high voltage increased to the polymer insulator was. It can be determined that the polymer insulator mounted on a live part must be examined when the discharge risk exceeds approximately 40%. In conclusion, the status of power utilities can be checked using an UV sensor.

• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.199-206
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• 2003

Because the MIRD phantom, the representative mathematical phantom was developed for the calculation of internal radiation dose, and simulated by the simplified mathematical equations for rapid computation, the appropriateness of application to external dose calculation and the closeness to real human body should be justified. This study was intended to modify the MIRD phantom according to the comparison of the organ absorbed doses in the two phantoms exposed to monoenergetic broad parallel photon beams of the energy between 0.05 MeV and 10 MeV. The organ absorbed doses of the MIRD phantom and the Zubal yokel phantom were calculated for AP and PA geometries by MCNP4C, general-purpose Monte Carlo code. The MIRD phantom received higher doses than the Zubal phantom for both AP and PA geometries. Effective dose in PA geometry for 0.05 MeV photon beams showed the difference up to 50%. Anatomical axial views of the two phantoms revealed the thinner trunk thickness of the MIRD phantom than that of the Zubal phantom. To find out the optimal thickness of trunk, the difference of effective doses for 0.5 MeV photon beams for various trunk thickness of the MIRD phantom from 20 cm to 36 cm were compared. The optimal thunk thickness, 24 cm and 28 cm for AP and PA geometries, respectively, showed the minimum difference of effective doses between the two phantoms. The trunk model of the MIRD phantom was modified and the organ doses were recalculated using the modified MIRD phantom. The differences of effective dose for AP and PA geometries reduced to 7.3% and the overestimation of organ doses decreased, too. Because MIRD-type phantoms are easier to be adopted in Monte Carlo calculations and to standardize, the modifications of the MIRD phantom allow us to hold the advantage of MIRD-type phantoms over a voxel phantom and alleviate the anatomical difference and consequent disagreement in dose calculation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.4
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• pp.213-218
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• 1970

Many investigations have been made on V. parahaemolyticus but to the author's knowledge a report on V. parahaemolyticus found in Korean coastal water has not yet been published. The authors have investigated distribution of V. parahaemolyticus in fish, shellfish, mud, crustacea, sea water and cephalopoda in order to determine the possible origins of food poisoning in Korea. The results are summarized as follows: 1. Fifty six of V. parahaemolyticus were isolated from 517 samples obtained from mud, sea water, fish, crustacea and cephalopoda. 2. The distribution of V. parahaemolyticus isolated from the samples was: 6 strains from mud samples, 7 strains from 44 sea water samples, 28 strains from 241 fish samples, 1 strain from 50 crustacea samples and 2 strains from 34 cephalopoda samples. 3. The strains isolated in the Mokpo area were 7 strains from 48 samples and those isolated in the Pohang area were 2 strains from 46 samples. The number of strains in the Mokpo area was the highest among the strains and the number of strains in the Pohang area was the lowest.