• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1170-1176
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• 2007

The conventional urodynamic monitoring is fulfilled by artificially filling a bladder with saline. Generally. it is difficult to evaluate the physiological functions of the storage and voiding of a bladder. With this aim, we constructed an ambulatory urodynamic monitoring (AUM) system and proposed a novel method estimating abdominal pressure by measuring bio-impedance variations. Our system was clinically evaluated for 10 patients. It turned out to be that as the intensity of the abdomen contraction increased, the amplitude of bio-impedance signal and the RMS value of EMG increased more as compared to those who observed during the rest mode. Also, we determined the optimum electrode pair for estimating the abdominal pressure using bio-impedance method and consequently compared with the conventional methods. Because impedance changes differ from a weight, a height, contractile force, volume of muscle and blood other or whatever of individuals, it was quantified in terms of impedance change, correlation coefficient and SNR Our results showed the optimum electrode pair (1,9) which could detect impedance changes due to the increase of the intensity in the abdominal pressure. The correlation coefficient and quadratic function between the RMS values of EMG and the impedance changes were 0.87 and $y=0.0014x^2+0.0620x+0.6958$, respectively. Thus, our system demonstrated that the abdominal pressure could be measured noninvasively and conveniently by simply estimating bio-impedance values. We propose that this optimum electrode configuration would be useful for the future studies involving the handy measurements of abdominal pressure with our suggested ambulatory urodynamics monitoring system.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.111-116
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• 1998

Silicon nitride is hard and tough ceramic material. Hereby, mechanical machinability is very poor. It has also high electrical resistance. Silicon nitride of extremely high electrical resistivity becomes conductive ceramic composite by adding 30 wt% TiN. Ceramics with high electrical conductivity can be electrical discharge machined. Using by the Electrical Discharge Machining (EDM) technique. $Si_3N_4-TiN$ ceramic composite with high electrical conductivity is utilized to make metal working tool. These tool materials have severe wear problem as well as oxidation. Post HIP processing after sintering $Si_3N_4-TiN$ ceramic composites was performed. The tribological property of $Si_3N_4-TiN$ composite as a function of content of TiN was investigated in air, at room temperature. The hardness, fracture toughness, and flexural strength were compared with the wear volume. SEM observation of wear tracks can make an explanation of wear mode of $Si_3N_4-TiN$ composite.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.59-69
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• 1997

The growth and microstructural characterization of epitaxial yttrium silicide ($YSi_2$) on the (100)Si substrate are investigated. The $YSi_2$ film grow epitaxilly through the solid phase reaction during vacuum annealing above $400^{\circ}C$. The epitaxial relationships between the hexagonal $YSi_2$ film and the (100)Si substrate are [0001]$YSi_2$//[011]Si and [0001]$YSi_2$//[011]Si in the (1100)$YSi_2$//(100)Si plane relation. The YSi$_2$ film consists of the two types of domains which have two different azimuthal orientations making an angle of $90^{\circ}$ to each other. The two types of domains in the $YSi_2$film are equivalent in volume fraction and crystalline quality, which has been proved from the equivalent integrated intensities of (2201) asymmetric reflection of X-ray diffraction. The formation of a double -domain structure is discussed on the basis of geometrical matching at interface between the (1100)$YSi_2$ film and the (100)Si substrate, and growth model is proposed.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.6
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• pp.580-586
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• 2010

Acid and alkali pretreatments were applied to tofu processing waste (TPW) to increase the solubility of ingredients in TPW. Pretreatment at 1.0% of HCl and 2.5% of NaOH condition resulted in the increase of SCOD concentration from 3.2 g COD/L to 27 g COD/L and 33 g COD/L, respectively. The acid and alkali-pretreated TPW was studied for its fermentative $H_2$ production capacity in batch mode using a thermophillic mixed culture. Alkali pretreatment on presence of 2.5% NaOH exhibited more soluble portion released compared to acid pretreatment using HCl, however the $H_2$ production from acid pretreated TPW was better than alkali-pretreated TPW probably due to the sodium inhibition on microbial activity. In addition, sewage sludge was externally added to the acid-pretreated (1.0% HCl) TPW by 20% (on volume basis). Average H2 production rate was increased from 31 to 78 ml/L-broth/hr, and it was attributed to the high buffer capacity and abundant nutrients especially divalent cation in sewage sludge.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.115-123
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• 2010

Cool-down performance after soaking is important because it affects passenger's thermal comfort. The cooling capacity of HVAC system determines initial cool down performance in most cases, the performance is also affected by location, and shape of panel vent, indoor seat arrangement. Therefore, optimal indoor designs are required in developing a new car. In this paper, initial cool down performance is predicted by CFD(computational fluid dynamics) analysis. Experimental time-averaging temperature data are used as inlet boundary condition. For more reliable analysis, real vehicle model and human FE model are used in grid generation procedure. Thermal and aerodynamic characteristics on re-circulation cool vent mode are investigated using CFX 12.0. Thermal comfort represented by PMV(predicted mean vote) is evaluated using acquired numerical data. Temperature and velocity fields show that flow in passenger's compartment after soaking is considerably unstable at the view point of thermodynamics. Volume-averaged temperature is decreased exponentially during overall cool down process. However, temperature monitored at different 16 spots in CFX-Solver shows local variation in head, chest, knee, foot. The cooling speed at the head and chest nearby panel vent are relatively faster than at the knee and foot. Horizontal temperature contour shows asymmetric distribution because of the location of exhaust vent. By evaluating the passenger's thermal comfort, slowest cooling region is found at the driver's seat.

• Korean journal of food and cookery science
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• v.14 no.1
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• pp.44-49
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• 1998

The microwave cooking of rice was studied for the purpose of establishing optimum conditions of power level and heating time. Optimum volume of adding water was 290 ml per 173 g rice. The longer the rice was soaked, the better the cooked rice. However, we chose one hour as soaking time so that we might observe well the effects of power levels. The mode of microwave cooking consisted of 5 steps of power level; step 1: temperature ascendance, step 2: water absorption 1, step 3: water absorption 2, step 4: heat penetration, step 5: gelatinization completion. The quality of cooked rice was evaluated subjectively. As a result of the study, 3 optimum conditions were chosen as follows. 1) (7) 5:00-(1) 5:00-(2) 5:00-(2) 6:00-(7) 4:00, 2) (8) 4:25-(1) 5:00-(2) 5:00-(2) 5:00-(6) 4:00,3) (9) 3:40-(1) 5:00-(2) 5:00-(3) 6:00-(7) 2:00

• Fire Science and Engineering
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• v.17 no.2
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• pp.62-69
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• 2003

The smoke control system in subway platform is not only using for smoke exhaust facility but also using ventilation system. For this reason, smoke vent effectiveness is depending on its position, ventilating volume capacity and the vent method. In this study, the passenger's evacuation time was calculated for the case of fire on sloped subway train vehicle in subway platform. In order to recommend the mechanical smoke exhaust operation mode, SES (Subway Environmental Simulation) was used to predict the airflow of the inlet and outlet tunnel for the subway station. Fire dynamics Simulator(FDS) was used the SES's velocity boundary conditions to calculate the smoke density and temperature under the condition of fire on stopped subway train vehicle at the platform. We compared smoke density and temperature distributions for each 6 types of smoke exhaust systems to clarify the characteristics of smoke and hot air exhaust effectiveness from the result of fire simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.443-450
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• 2011

The Internet has become an essential part in our modern life by providing useful information. So, the volume of Internet traffic has been increasing rapidly, which emphasizes the importance of network traffic analysis for effective network operation and management. Signature based analysis have been commonly used, but it is shown that the increase of signatures due to the increase of applications causes the performance degradation of real-time traffic analysis on high-speed network links. In this paper, we propose OS fingerprinting method for real-time traffic analysis. The previous problems can be solved by utilizing the OS information. The OS fingerprinting method for real-time traffic analysis, proposed in this paper, conducts under passive mode, and improves the limitation of a previous method such as low completeness and accuracy. In this paper, we enlarged an input data to improve completeness, and used the User-Agent field in HTTP packet to extract various OS signatures. Also, we changed an input data from packet to flow to improve accuracy.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.79-80
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• 2014

Most of marine pollution have been occurred by oil spill accidents resulted from ship accidents in South Korea. This year there were two large oil spill accidents: the Yeosu Oil Spill Accident (2014.01.31.(Fri.) 09:35 LT) and the Captain Vangelis L. Oil Spill Accident (2014.02.15.(Sat.) 14:00 LT). In general, Synthetic Aperture Radar (SAR) is used in monitoring and detection of oil dumping and spilled oils by accident at sea. Therefore it is expected that KOMPSAT-5, launched successfully last year, will take part in that mission during a normal operation mode. After the two accidents, high spatial resolution optical satellite data including KOMPSAT-3 were acquired February 2 and 14, 2014. In this presentation, we analyzed optical properties of spilled oils from optical satellite imagery to estimate the spilled area and the volume at each region. Finally, a satellite application planning for ocean surveillance in South Korea will be presented.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.4
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• pp.293-305
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• 2017

This experiment was conducted to evaluate the effect of leachate replacement frequency on solid state anaerobic digestion (SSAD) of dairy manure using 22 L volume lab-scale digesters at mesophilic temperature ($37^{\circ}C$) in batch mode. Three different leachate replacement strategies (no replacement, once every three days, and once every nine days) were applied and three digesters per each treatment were operated for 45 days. Results showed that leachate replacement test unit every nine days resulted in 1.6 times more methane production ($53.8N{\cdot}mL\;g^{-1}{\cdot}VS$) from SSAD compared to test unit every three days ($34.0N{\cdot}mL\;g^{-1}{\cdot}VS$). No leachate replacement strategy applied group showed slightly higher methane production ($56.3N{\cdot}mL\;g^{-1}{\cdot}VS$) than every nine days replaced one. When added the methane production potential of replaced leachate itself to the methane produced from digester, leachate replacement every nine days resulted in quite similar methane production ($56.5N{\cdot}mL\;g^{-1}{\cdot}VS$) to no leachate replacement group. Even though methane production potential of replaced leachate itself added to the methane produced from digester, every three days replacement showed only $34N{\cdot}mL$ methane production per gram of volatile solids. These results suggest that farmers do not need to replace leachate during SSAD of dairy manure and sawdust mixture in order to maximize methane production. If there are any concerns with accumulation of inhibiting substances in the digester, the 9-day cycle leachate replacement is appropriate.