• Korean Journal of Food Science and Technology
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• v.38 no.2
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• pp.169-175
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• 2006

Potentiometric biosensor using flow injection analysis system was developed to determine citrate concentration in foods. Biosensor system consisted of sample injector, peristaltic pump, enzyme reactor, carbonate ion selective solid-state electrode, reference electrode, detector, and recorder. Enzyme reactor was prepared with immobilized citrate lyase and oxaloacetate decarboxylase. Carbonate ions produced through enzyme reactions of citrate were potentiometrically detected by ion selective electrode. Optimum conditions for biosensor system were investigated. Interference effect of major sugars and organic acids was less than 5% on citrate biosensor system. Citrate concentrations in fruit juices were determined by biosensor and gas chromatography. No significant difference was observed between two analytical methods. Results indicate citrate biosensor is useful in determining citrate concentration in foods.

• Journal of the Korean Geosynthetics Society
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• v.16 no.2
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• pp.97-107
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• 2017

Recently, there have been a lot of incidents related to ground sinks in urban areas, but restoration work is complicated and inconvenience due to on-site control, and particularly, grouting and soil filling are generally applied as recovery measures, but when the grouting or the soil filling is carried out, material segregation phenomenon occurs in the ground or a lot of restoration amount is often required, depending on the state of sinks and the existence of groundwater under the ground and the soil can be lost due to the flow of the ground water, and thus the purpose of this study is to develop a pouch-type filler applied to a trenchless method for emergency reinforcement of the ground sinks with the aim of quick recovery of the ground sink in urban areas, and as a result, it was confirmed that compression strength and the expansion ratio were different according to the temperature of ground water and the compression strength and the expansion ratio could be controlled by mixing alumina powder.

• Journal of the Korean GEO-environmental Society
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• v.8 no.4
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• pp.67-74
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• 2007

Many studies for slope stability studies have indicated that the infiltration of rainwater into a slope decrease the slope stability. In order to minimize damage caused by slope failure, most design codes suggest that the slope stability be analyzed by saturated condition during rainy season. However it would be excessively conservative condition that every soil slope is saturated in rainy season irrespective of rainfall intensity, soil type and slope geometry. In addition, because most soil slopes are in an unsaturated state, it is necessary to consider the unsaturated characteristics of slope. This paper suggests a prediction method of saturation time for the weathered granite soil slopes due to rainfalls. The finite element analysis of transient water flow through unsaturated slope was used to investigate effects of soil-water characteristics, permeability at saturation, slope geometry, and rainfall intensity. From the result of these analyses, the prediction charts considering soil-water characteristics, permeability at saturation, and slope height were proposed in this study. It is possible to the time required to be saturated slope after rainfall.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.89-93
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• 2003

The Korea Research Institute of Ships and Ocean Engineering (KRISO), the ocean engineering branch of KORDI, has designed and manufactured a model of an autonomous underwater vehicle (AUV) to test underwater docking. This paper introduces the AUV model, ASUM, equipped with a visual servo control system to dock into an underwater station with a camera and motion sensors. To make a visual servoing AUV, this paper implemented the visual servo control system designed with an augmented state equation, which was composed of the optical flow model of a camera and the equation of the AUV's motion. The system design and the hardware configuration of ASUM are presented in this paper. A small long baseline acoustic positioning system was developed to monitor and record the AUV's position for the experiment in the Ocean Engineering Basin of KRISO, KORDI. ASUM recognizes the target position by processing the captured image for the lights, which are installed around the end of the cone-type entrance of the duct. Unfortunately, experiments are not yet conducted when we write this article. The authors will present the results for the docking test of the AUV in near future.

• Journal of Ocean Engineering and Technology
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• v.32 no.5
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• pp.380-385
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• 2018

With the tightening of environmental regulations (i.e., IMO Tier III), natural gas (NG) has been spotlighted as an eco-friendly fuel with few air pollutants other than nitrogen oxides (NOx) and sulfur oxides (SOx). For reasons of economic efficiency, it is mainly stored and transported in a liquid state at $-163^{\circ}C$, which is a cryogenic temperature, using a liquefied gas storage tank. Accordingly, it is necessary to reduce the boil-off gas (BOG) occurrence due to the heat flow according to the temperature difference between the inside and outside of the storage tank. Therefore, in this study, a BOG measurement test on an independent-type storage tank made up of SUS304L was carried out. The test results showed the tendency for BOG occurrence according to the temperature under different filling ratios.

• Journal of the Korean Institute of Gas
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• v.22 no.1
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• pp.1-8
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• 2018

FCV is installed with a automatic valve attached in an high pressure cylinder to control the hydrogen flow. The supply of hydrogen from the cylinder into the fuel cell stack is controlled via the on/off operation of a solenoid attached to the automatic valve. The solenoid needs to provide the necessary attraction force even at any saturation temperature caused by drive of the vehicle. In this study, the simplified prediction equations for the saturation temperature are suggested. The finite element analysis was performed by steady state technique, according to the boundary condition in order to predict the saturation temperature and attraction force. Finally, the saturation temperature was validated through comparison between the analysis results and measurement results. From the results, the measured saturation temperature $5.9^{\circ}C$ lower with respect to the analysis results. And the error of attraction force ranged from 1.0 to 2.1 N at testing conditions.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.1
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• pp.45-48
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• 2016

The treatment of obesity have been developed various devices for the treatment of obesity, the ultrasound is to be made after the state changes to become easy fat decomposition by heat and vibrations to facilitate the flow of blood and lymph fatty acid released into the blood. There is such ultrasonic transducer array is used in obesity therapy focusing angle of the transducer array and the frequency may have a significant impact on the degradation of fat. In this paper, we set the frequency that reaches the shortest time to a set temperature 27kHz, 1MHz, by applying a transducer with a diameter of 5mm, 10mm, 16mm for the frequency of 3MHz, obtain the wavelength and near the stomach in order to set the frequency of the transducer array, which was set to the focusing angle of the transducer with three contact surfaces. As a result, the time to reach the set temperature was short days when 3MHz frequency, the focusing angle is titrated is $40^{\circ}$.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.1
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• pp.38-45
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• 2009

To get the constant output, synchronous generator field excitation is controlled by AVR(Automatic Voltage Regulator). Most of ships generator AVR uses the thyristor phase controlled rectifier. However this rectifier is difficult to realize that the fast control system because its control period is slower than MOSFET and IGBT type converter. Therefore, this paper deals with PMG(Permanent Magnet Generator) type digital AVR using MOSFET switch for ships synchronous generator. The composition of this digital AVR is very simple, the generator is under the short circuit accident, the output voltage becomes zero state and AVR can not operate. Thus generator is required to add CBC(Current Boosting Circuit) in an excitation circuit to flow output current. The performance of the proposed system is evaluated on a 10[kVA] experimental prototype circuit in place of real ships generator.

• Journal of Pharmaceutical Investigation
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• v.30 no.4
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• pp.247-252
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• 2000

The advantages of transdermal administration are avoiding hepatic first pass effect, minimizing inter- and intra-patient variation, maintaining steady-state plasma level to provide long-term therapy from a single dose, and allowing a rapid termination of drug input. Clenbuterol, a selective ${\beta}_2-adrenergic$ receptor stimulant, has been introduced as a potent bronchodilator for patients with bronchial asthma, chronic obstructive bronchial disease. For the development of transdermal systems containing clenbuterol, two limiting factors - long lag time and low flux - must be overcome. In this study, we attempted to select optimal formulation for preparation of clenbuterol patch using hairless mouse skin and flow-through diffusion cell. The flux of clenbuterol increased as the percent of clenbuterol dose dependently in the concentration range of 5-15%. Based on this result, we fixed the concentration of clenbuterol as 15%. The effect of various penetration enhancers on percutaneous absorption of clenbuterol through hairless mouse skin was investigated. Labrafil was the most effective enhancer, which increased the permeability of clenbuterol approximately 4-fold compared with the control without penetration enhancer. Optimal enhancer concentration was 3%. The effect of various adhesives on penetration of clenbuterol was also investigated. Among the adhesives studied, MA-31 was the most effective adhesive. Furthermore, the clenbuterol patch composed of 15% clenbuterol, 3% Labrafil and 82% MA-31, which gave most excellent penetration of drug in in vitro penetration study, maintained therapeutic plasma levels in in vivo study using S.D. rats. These studies demonstrated a good feasibility of clenbuterol administration through the intact skin using a transdermal patch, and show a possibility of the development of clenbuterol patches.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.177-183
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• 2008

In the study, we carried out a 3-D analysis to assess the influence of groundwater level changes on the slope stability, conducting a series of back-numerical analysis to delineate the critical line of the shear strength of the failure surface of a landslide, and a laboratory test to determine the geo-mechanical properties of soil samples. The analysis result shows that the shear strength determined by the laboratory test was distributed below the critical line of shear strength estimated by back-analysis. Differences between driving and resisting force were also analyzed in groundwater conditions of dry and saturation. It appeared that the stress gets greater towards the slope center of the landslide, and the debris mass moves downwards. According to the analysis, the factor of safety becomes 1 with the rise of foundwater level up to -0.85 m from the slope surface, while the slope tends to stay stable during dry seasons.