• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.9
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• pp.18-26
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• 1999

Recently, multiuser detection has been investigated as an interesting topic because of its capability of eliminating multiuser interference and resistance to the near-far problem. In this paper, we consider a quasi maximum likelihood detector in the reverse link system which used antenna arrays in quasi-synchronous channels. It is also shown that the proposed system can suppress the interuser interference without using the side information of the other users. It is also shown that the performance of the proposed system is superior to that of the conventional matched filter system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1619-1625
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• 2018

Portable electronic devices secondary batteries can cause fire and explosion due to micro-current change in addition to the situation of short-circuit inrush current, safety can not be secured with a general operation limited current fuse. Therefore, in secondary battery, it is necessary for the protector to satisfy both the limit current type operation in the open-short-circuit inrush current and the current detection operation characteristic in the micro current change situation and for this operation, a fuse for the current detection type secondary battery protection circuit can be applied. The purpose of this study is to design a protection device that operates stably in the hazardous situation of small capacity secondary battery for portable electronic devices through the design of low melting fuse elements alloy of sensing type fuse and secures stability in abnormal current state. As a result of the experiment, I-T and V-T operation characteristics are satisfied in a the design of the alloy of the current sensing type self-contained low melting point fuse and the resistance of the heating resistor. It is confirmed that it can prevent accidents of short circuit over-current and micro current change of secondary battery.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.223-228
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• 2019

We fabricated a printed Ag:CNT film as a liquid sensor for the detection of HNS (hazardous and noxious substances) in seawater. The paste required for printing was prepared using Ag powder, MWCNTs (multi-walled carbon nanotubes), and an organic binder. The heat treatment process for binder removal was optimized. In order to confirm that the sensor was operational, the resistance change characteristics in brine (3.5%) and methanol (99.8%) were assessed at $20^{\circ}C$. EDL (electrical double layer) formation and redox reactivity were confirmed as the most important reactions affect each electrical property of sensor in brine and methanol. From these results, it was determined that printed Ag:CNT film can be applied as a sensor to detect HNS in seawater.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2373-2379
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• 2023

In sodium systems, leakage is one of the safety concerns; it can cause chemical reactions, which may result in fires. There are contact and non-contact types of leak detectors, and the conventional method of non-contact type detection is by gas sampling. Because of the complexity of this method, there has always been a need for a simple gas sensor, and the resistive-type nanostructure ZnO sensor is a promising option with various advantages. In this study, a ZnO sensor was fabricated, and the concept was tested as a leak detector using a dedicated experiment facility. The experiment results showed distinctive changes in resistance with the presence of sodium aerosol under various conditions. Replacing the conventional gas sampling with the ZnO sensors is expected to enable identification of the leakage location if used as a point-wise instrumentation and to greatly reduce the total cost, making the system simple, light, and effective. For further study, more tests will be performed to evaluate the sensitivity of key parameters under various conditions.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.979-985
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• 2010

This study was performed to detect enterococci strain as an indicator of faecal contamination, to identify of 16S rDNA sequence and vancomycin resistance by MIC (Minimum Inhibitory Concentration) test from drinking spring-water samples in Seoul. The detection frequency of enterococci was 42 (19.8%) among 212 samples, and its concentration was ranged from 0 to 110 CFU/100 mL. These results were confirmed the possibility as an indicator microorganisms that similar to the frequency of E. coli detection (t test p-value 0.268, significant level 0.05). Isolated 56 enterococci samples were identified by 16S rDNA sequence data and their NCBI BLAST searching. They were identified to Enterococcus faecalis of 24 samples, E. faecium (10), E. casseliflavus (10), E. gallinarum (3), E. hirae (2), E. durans (2), E. sanguinicola (1). E. faecalis was dominant species that clinical case report of a domestic was similar. Vancomycin resistant enterococci (VRE) of 53 samples showed that vanB and vanC1/C2 type with 2 and 12 case, respectively. These results indicated that the drinking spring-water quarantined to fecal pollution for block out outbreak of gastrointestinal symptom with using such as disinfection process.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.4
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• pp.363-370
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• 2020

This paper reports the results of an experimental study using the BOTDR sensor to detect the unbonded location of attached CFRP sheet for structural rehabilitation. A specimens with the unattached CFRP sheet were fabricated for this study, on which BOTDR sensor was attached with a nylon net. During the flexural test of the specimens, the strain of the CFRP sheet was measured using the BOTDR sensor and electric resistance gauges. From the results, it was confirmed that the strain distribution obtained through the BOTDR sensor can be effectively used to visualize and detect the unbonded position of the CFRP sheet. In addition, In addition, the strain measured by the BOTDR sensor was found to be more effective in analyzing the overall structure behavior than the electric resistance strain gauge. The development of a BOTDR sensor with a measuring longth of less than 100 mm will enable accurate detection of the local unbonded position of the CFRP sheet.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.137-137
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• 2003

Conducting PPy/PVA composite and pure PPy gas sensors were prepared by in-situ vaporstate polymerization method in a vaporization chamber under N2 condition, by exposing the pre-coated electrode with PVA/FeC13 to distilled pyrrole monomer. The various electrical sensing behaviors of both types of sensors were systematically investigated by a flow measuring system including mass flow controller (MFC) and bubbling bottle. The FT-Raman spectroscopy of vapor state polymerized PPy was identical to that of chemically polymerized PPy, confirming the same chemical structure. Both types of sensors had positive sensitivity when exposed to methanol gas. The sensitivity varied linearly with gas concentration in the range of 50ppm to 1059ppm. The detection limit of PPy/PVA sensor was believed to be as low as 10ppm. The sensitivity of PPy/PVA composite sensor was higher than that of pure PPy sensor. Both the response time and recovery time of PPy/PVA composite sensors were longer than those of pure PPy sensors. The thickness of the sensing film affected the sensitivity this way that the sensor having thinner film had higher sensitivity, indicating that the resistance of polymer film involved in the sensing behavior was bulk resistance rather than surface resistance. The reproducibility of PPy/PVA composite sensor was excellent during eight on-off cycles by switching between N2 and 3000ppm methanol gas. The sensitivity of PPy/PVA composite sensor was only maintained for two weeks, while the sensitivity of pure PPy sensor was maintained over two months.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.257-261
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• 2014

Carbon nanotubes (CNT) has the excellent physical characteristics in the sensor, medicine, manufacturing and energy fields, and it has been studied in those fields for the several years. We fabricated the NOx gas sensors of MOS-FET type using the MWCNT. The fabricated sensor was used to detect the NOx gas for the variation of $V_{gs}$ (gate-source voltage) with the ambient temperature. The gas sensor absorbed the NOx gas molecules showed the decrease of resistance, and the sensitivity of sensor was reduced by the NOx gas molecules accumulated on the MWCNT surface. Furthermore, when the voltage ($V_{gs}$) was applied to the gas sensor, the term of the decrease in resistance was increased. On the other hand, the sensor sensitivity for the injection of NOx gas was the highest value at the ambient temperature of $40^{\circ}C$. We also obtained the adsorption energy ($40^{\circ}C$) using the Arrhenius plots by the reduction of resistance due to the $V_{gs}$ voltage variations. As a result, we obtained that the adsorption energy also was increased with the increasement of the applied $V_{gs}$ voltages.

• The Journal of Korean Obstetrics and Gynecology
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• v.19 no.3
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• pp.191-201
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• 2006

Purpose : Skin Resistance Variability(SRV) is a kind of biofunctional signal, and it can show the function of autonomic nervous system, especially in the sympathetic nerve. The objective of this study is to find out the differences of SRV of reproductive women with aging. Method : We measured SRV(by CP-6000A) of 151 women who visited Gynecologic Clinic. And the results were classified according to age, by five groups. After detection of SRV, we performed correlation analysis and ANOVA by SPSS 12.0. Results : 1. The SRV was measured twice. It resulted in seven areas. In 1, 2, 3 areas, the second results were higher than first results in every groups. In 4, 5, 6, 7 areas, the first results were higher than second results in every groups. 2. The SRV of lower part (4, 5, 6, 7 area) on the body was higher than that of higher part (1, 2, 3 area). 3. The SRV in the youngest group was higher than the oldest group in 1, 2, 3 area of second trial. Conclusion : With relations to the standardization and objectification of oriental medicine, we expect that these results contribute to gynecologic clinic in the department of diagnosis of functional abnormality of hypothalamus-hypophysis-ovarian axis (H-P-O axis).

• The Journal of Korean Obstetrics and Gynecology
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• v.20 no.2
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• pp.176-187
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• 2007

Purpose: Recent studies show that Skin Resistance Variability(SRV) could be related to the functions of Hypothalamus-Pituitary-Ovary(H-P-O) axis. 7-Zone-Diagnostic System is oriental medicine measuring system using SRV. To know the differences of SRV of normal and abnormal menstrual cycle groups, we research the SRV of the two groups. Methods: We measured SRV of two groups that were consist of 126 women who took CP-6000A test in Sangji Oriental Medical Hospital from Mar. 2004 to Feb. 2006. After detection of SRV, we performed correlation analysis by SPSS 12.0. Results: The SRV was measured twice in 7 areas. By the results of 1st trial on Factor AA of the SRV, the patient group's results were lower than normal group's results in all 7 areas. And there were remarkable differences in 1, 2, 3, 4, 5, 7 areas between two groups. By the results of 2nd trial on Factor AA of the SRV, the patient group's results were lower than normal group's results in all 7 areas similar to 1st trial results. And there were remarkable differences in 2, 3 areas between two groups. Conclusion: Comparing normal group with patient group, these results may reflect the relations of abnormal menstrual cycle and H-P-O axis functions. Because patient's results were lower than normal's in all 7 areas. And remarkable different results in 2, 3 areas were repeated by twice trial all. Further study will be needed.