• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.4
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• pp.753-762
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• 2024

Tunnels have limited evacuation areas, and It is difficult for cars coming from behind to recognize the accident situation in front. Since an accident is very likely to lead to a serious secondary accident, a IoT-based smart tunnel accident warning system was studied to prepare for traffic accidents that occur in tunnels. If the measured values from the flame detection sensor, gas detection sensor, and shock detection sensor in the tunnel exceed the standard, it is judged to be an emergency situation and an alert system is designed to operate. The accident information message was designed to be displayed on the LCD and transmitted to drivers inside and outside the tunnel through a Wi-Fi communication network. A performance test system was established and performance evaluation was performed for several accident scenarios. As a result of the test, it was confirmed that the accident alert system can accurately detect accidents based on given reference values, perform alert procedures, and transmit alert messages to smart phones through Wi-Fi wireless communication. And through this, its effectiveness could be confirmed.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2009-2014
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• 2007

Hydrogen is a fuel of fuel cell system, which has powerful explosion possibility. Hence, the fuel cell system needs safety evaluation to prevent risk of hydrogen leakage. We use a actual size chamber of a common fuel cell module to analyze hydrogen. Hydrogen injection holes are located in lower part of the chamber in order to simulated hydrogen leakage. The hydrogen sensor can detect range of 0${\sim}$4%. Since the hydrogen gas, of which leaked amount is controled by MFC, are injected at the bottom holes, the transient sensor signals are measured. At a condition of 10cc/s of hydrogen leakage, the sensor detects hydrogen leakage after 22sec and there is also several seconds of time delay depending on the position of the sensor. This experimental data can be applied for the design of the hydrogen detection system and ventilation system of a residential fuel cell system.

• Korean Journal of Pharmacognosy
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• v.44 no.4
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• pp.350-361
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• 2013

Asarum sieboldii has been used for treatment of fever, pain, common cold, and chronic sinusitis in Korea. In this study, we performed quantification analysis of seven major constituents including aristolochic acid I, aristolochic acid II, ${\alpha}$-asarone, ${\beta}$-asarone, elemicin, methyl eugenol, and safrole in the 70% ethanol extract of Asarum sieboldii and its solvent fractions, n-hexane, ethylacetate, n-butanol, and water ones using a ultra-performance liquid chromatography-electrospray ionization-mass spectrometer(UPLC-ESI-MS) and gas chromatography-mass spectrometer(GC-MS). Regression equations of seven components were acquired with $r^2$ values >0.99. The values of limit of detection(LOD) and quantification(LOQ) were 0.1-3.9 ng/mL and 0.3-11.7 mg/mL, respectively. The amount of the seven compounds in Asarum sieboldii were not detected -143.66 mg/g. The established LC-MS/MS and GC-MS methods will be helpful to improve quality control of Asarum sieboldii.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.3
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• pp.472-480
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• 1994

Allicin was synthesized for the purpose of identification an dquantitation of a pharmaceutical dosage form in soft capsules. The identified transformed products fro allicin were dially disulfide , 3-vinyl-[4H]-1, 2-dithiin and 2-vinyl-[4H]-1, 3-dithiin in gas chromatrographic conditions and dially disulfide and ajoene in HPLC. Allicin is thermally unstable , it may be completely decomposed to vinyl dithiin isomers in GC conditions. For that reason, allicin was not found directly in the pharmaceutical dosage forms. In HPLC conditions, mobile phase was methanol /water containing 0.1% formic acid(65/35) and column was $\mu$-Bondapak C18. Detection wa-velength was 254nm. The retention time of allicin was 6.98min. The calibration ranger for allicin was 10 $\mu\textrm{g}$/ml to 200$\mu\textrm{g}$/ml and correlation coefficient(r) was 0.987.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.36-47
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• 1999

Three-way catalyst converter, cleaning up the exhaust gas contamination of SI engine, has the best efficiency when A/F ratio is near the stoichiometry . The feedback control using oxygen sensors in the exhaust manifold has limits caused by the system delays. So the accurate measurement of air flow rate to an engine is essential to control the fuel injection rate especially on transient condition like the rapid throttle opening and closing. To measure the rapid change of flow rates. the air flow meter for the engine requires quick response, flow reversal detection, and linearity . Tjhe proposed integration type air flow meter (IFM), composed of an ultrasonic flow meter with an integration circuit, has significantly improved the measurement accuracy of air mass inducted through the throttle body. The proposed control method estimated the air mass at the cylinder port using the measured air mass at the throttle . For the fuel dynamic model, the two constant fuel model is introduced . The control parameters from air and fuel dynamics are tuned to minimize the excursion of the air fuel ratio. As a result A/F ratio excursion can be reduced within 5% when throttle rapidly opens and closes at the various engine conditions.

• Journal of Veterinary Clinics
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• v.13 no.2
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• pp.153-157
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• 1996

Ketosis can exist in both clinicla and subclinical forms. Detection of the subclinical form of ketosis by the use of a nitroprusside based test powder gas been shown to be a relatively simple and reliable procedure. Howere, very liffle is known about the indcidence or prevalence of the subclinical ketosis in Korea. In the present study, samples of urine taken from 288 dairy cows in Chonnam area were examined to demonstrate the presence of ketone bodies, using ross test. All the cows were within 4 weeks either before or after parturition. The gerd size was from 10 to more than 100 cows, and the cows did not show any clinical signs of ketosis. Of the 288 cows, 85 (29.5%) were positive to Ross test; of the positive cases 42.4% were +, 44.7% were ++, and the remaining 12.9% were +++. The prevalence increased from 3rd parity, peaked at 6th parity and thereafter decreased. The prevalence was higher after parturition than before parturition, with the highest occurrence during the 2nd week after calving. The prevalence was higher during winter. Also cows kept indoor throughout the year showed higher occurrence of the subclinical ketosis. The subclinical ketosis did not affect the specific gravity of the urine; however, increasing amount of ketone bodies in the urine decreased the pH of urine.

• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.298-302
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• 2004

Thick films of $LaNiO_{3}$ having perovskite structure impregnated with indium and bismuth oxides have been used as sensing material for acetonitrile ($CH_{3}CN$) gas. The sensor response for $CH_{3}CN$ is quite good with an excellent recovery for partial pressure from 3 ppm to 20 ppm between 200 and $250^{\circ}C$. $LaNiO_{3}$ alone has exhibited low response, but after impregnation of $In_{2}O_{3}$ and $Bi_{2}O_{3}$ have given increased sensitivity even with 3 ppm partial pressure of $CH_{3}CN$ at $200^{\circ}C$. It is assumed that $CH_{3}CN$ is undergoing oxidation reaction on surface of the film.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.2
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• pp.133-141
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• 2011

In this study, different calibration approaches for reduced sulfur compounds (RSCs) were investigated by using thermal desorption coupled with gas chromatography (GC) and pulsed flame photometric detection (PFPD). To evaluate the effects of calibration procedures, gaseous standards of 4 RSCs ($H_2S$, $CH_3SH$, DMS, and DMDS) prepared at 10 ppm level were analyzed at 7 loading injection volumes (40, 60, 80, 100, 160, 240, and 320 ${\mu}L$). The results were then compared with calibration curves made with the Z (zero offset) and N (non-zero offset) method. The concentrations of unknown samples were then quantified by using R (ratio) method in which the slope values are compared between standards and samples. Secondly, in A (average) method, results obtained from a multi-point analysis of unknown samples were also averaged to extract representative values for each sample. Results of both experiments showed that analytical error of low molecular weight components (such as $H_2S$ and $CH_3SH$) was greatly expanded with the Z method. In conclusion, the combined application of N-A method was the more realistic approach to reduce biases in the quantification of RSCs.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.4
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• pp.268-273
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• 2005

The spirometer is a medical device that measures the instantaneous velocity of the respiratory gas flow capacity. It is used for testing the condition of the lung and patient monitoring. It measures the absolute capacity difference that includes the flow capacity signal. In this paper, by using an ultrasound sensor that reduce+ the error caused by the inertia and pressure it has improved the transmission and receiving signal. This has enabled patients with weak respiratory to use the spirometer. Also, by using the ARM 920T Processor, a precise and prompt detection system was implemented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.100-108
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• 2005

In this paper deals with the frequency control of the HVDC scheme linking Haenam to Cheju Island. The primary aim of the study is to develop and evaluate a new frequency control that can be employed without having to utilise the existing Synchronous Compensators(Gas Turbines). Transient condition studies are performed utilising the detailed control strategies for the HVDC link, implemented in PSCAD/EMTDC. Study cases are completed involving synchronous compensators trip and load ripping events and study plots presented. It is demonstrated that the existing frequency measurement can be replaced by one derived from the AC network alone, incorporated into a new frequency control algorithm and gives effective frequency control and dynamic performance.