• Journal of the Korean Geosynthetics Society
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• v.8 no.3
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• pp.35-44
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• 2009

The purpose of this study was to prevent spreading of contaminants from movement of underground water by creating a barrier using artificial freezing method on a soil contaminated by oils and various NAPLs. Specimens with 80% and 90% degrees of saturation were prepared to form freezing barrier using artificial freezing method. With increasing freezing time of freezing barrier, barrier was formed faster in the specimen with 90% degree of saturation by about an hour compared to the specimen with 80% degree of saturation. In addition, thinnest thickness of frozen barrier in both specimens was 50mm after 12 hours of freezing time, showing expansion of freezing area with time. The results of this study can be applied to barrier in waste reclamation sites and contaminated regions or to flow control of contaminants.

• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.11-18
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• 2010

In this study, the pulse of radial artery and oxygen saturation are detected using photoelectric plethysmograph method. Using our device designed reflection type, we can detect the reflected light by radial artery and by switching circuit, we can also separate to 625nm band signal and 940nm band signals. The separated signals are converted as a pulse data by the pulse signal processing circuit. In this study, the reflection type of oxygen saturation calculation method is applied instead of the transmission type because of the reflection type sensor is used to measure the radial artery. As a result, we can detect about 97% accuracy of the oxygen saturation compare with the conventional method. For the accurate signals, the wrist band with sensor was designed and fixed on the radial artery. As a result, this wrist band type sensor was applicable to prevent position errors from motion artifact and could increase the accuracy during the measuring.

• Korean Journal of Optics and Photonics
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• v.20 no.5
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• pp.276-280
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• 2009

A Cr:YAG crystal was used as a saturable absorber for passive Q-switching of a Nd:$YVO_4$ laser which was pumped by a 1-W continuous wave laser diode. The first surface of the Cr:YAG was high-reflection coated for the pump wavelength. The high-reflection coating improved the absorption efficiency of the pump beam in the Nd:$YVO_4$ through double pass absorption. It also prevented pump beam induced partial bleaching of the Cr:YAG. The peak-to-peak pulse fluctuation of passively Q-switched laser output was approximately 4 %. The minimum pulse-width was measured to be 7.11 ns. Also, the average pulse repetition rate was 9 kHz and the maximum output power was 16.27 mW.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.372-378
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• 2005

Calcium Carbonate Saturation Index (LI: Langelier Index), an indicator of $CaCO_3(s)$ saturation, indicates corrosiveness of drinking water and it has been used to monitor drinking water conditions in USA, E.U, and Japan. The objective of this research was to measure LI parameters including water temperature, pH, total alkalinity, calcium ion concentration, and electric conductivity, and to evaluate possibility of using LI in domestic system. Results showed that water temperature varied from 2.0 to $26^{\circ}C$ during 15 months, indicating an average annual temperature of $23.9^{\circ}C$. Total alkalinity was from 20 to 45 mg/L. The concentration difference between total alkalinity and $HCO_3{^-}$ value was hardly observed; the concentration of total alkalinity can be replaced by that of $HCO_3{^-}$. Tap water had a medium corrosiveness since LI values were from 2.0 to 0.5. To reduce the corrosiveness and to increase LI values of drinking water, the results of this study showed that chemicals such as $Ca(OH)_2$, $CaCO_3$, NaOH, or $NaHCO_3$ should be added to water treatment plants.

• Korean Journal of Food Science and Technology
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• v.50 no.3
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• pp.324-330
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• 2018

In this study, we examined the effects of carrier oil type (MCT oil: MO, corn oil: CO, palm oil: PO), pH of dispersion solution, and antioxidants on the chemical degradation of ${\beta}$-carotene in oil-in-water nanoemulsions. The pH of the emulsion had a significant influence on the stability of ${\beta}$-carotene, which showed rapid degradation in emulsions at low pH value and relatively higher stability at high pH values. The influence of the carrier oil type on ${\beta}$-carotene stability was assessed. The rate of ${\beta}$-carotene degradation increased in the following order: CO > PO > MO. The effect of antioxidants on ${\beta}$-carotene degradation was monitored during storage at $25^{\circ}C$ for 4 weeks. The rate of ${\beta}$-carotene degradation decreased upon addition of water-soluble (ascorbic acid) or oil-soluble (tocopherol) antioxidants. In general, tocopherol was more effective than ascorbic acid in reducing ${\beta}$-carotene degradation. To utilize this nanoemulsion for producing acidic beverages, adding a higher concentration of antioxidants is required.

• Journal of the Korean Vacuum Society
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• v.17 no.1
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• pp.9-15
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• 2008

Various diatomic inorganic films and their composite films are packed as passivation films covering Ca cells on glass substrates by using an electron-beam evaporation technique. When these Ca cells are exposed to an ambient atmosphere, the water vapor penetrating through the passivation layers is absorbed in the Ca cells, resulting in a gradual progress of transparency in the Ca cells, which can be represented by changes of the optical transmittance in the visible range. Compared with the saturation times for the Ca cells to become completely transparent in the atmosphere, the protection effects of water vapor are estimated for various passivation films. The composite films consisting silicon oxide($SiO_2$) and tin oxide($SnO_2$) or zinc oxide(ZnO) are found to show a superior protection effect of water vapor as compared with diatomic inorganic films. Also, the main factors affecting the permeation of water vapor through the oxide films are found to be the polarizability and the packing density.

• Journal of the Korean Institute of Gas
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• v.5 no.2 s.14
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• pp.62-68
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• 2001

Overpressure in pipeline attached to outlet of LPG vaporizer has been studied to provide countermeasures to prevent it. The cause of liquefaction in pipeline was reviewed using vapor pressure curve with temperature, pressure, and composition to suggest method of controlling such parameters. Performance of vaporizer has been tested to detect defective design of float ball, and then improved scheme was suggested. Trouble of regulator attached to vaporizer was also studied to give countermeasures.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.1
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• pp.117-122
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• 2016

In this paper, we propose 24-GHz CMOS radio frequency (RF) power amplifier for short-range automotive collision avoidance radars. This circuit contains common source stage with inter-stages conjugate matching circuit as a class-A mode amplifier. The proposed circuit is designed using TSMC $0.13-{\mu}m$ mixed signal/RF CMOS process ($f_T/f_{MAX}=120/140GHz$). It operates at the supply voltage of 2V, and it is designed to have high power gain, low insertion loss and low noise figure in the low supply voltage. To reduce total chip area, the circuit used transmission lines instead of the bulky real inductor. The designed CMOS power amplifier showed the smallest chip size of $0.1mm^2$, the lowest power consumption of 40mW, the highest power gain of 26.5dB, the highest saturated output power of 19.2dBm and the highest maximum power-added efficiency of 17.2% as compared to recently reported results.

• The Journal of Engineering Geology
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• v.9 no.1
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• pp.1-15
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• 1999

An artificial recharge test was performed to analyze the source of seepage observed inside the Songsanri tombs Kongju during the rainy season. In order to simulate simulate the test, a two-dimensional unsaturated groundwater flow model was developed. By the measured water level variation in the observation wells and in the artificail water tank, the model was cailbrated to estimate the model parameters such as fitting parameters in the constitutive relations(n and $\alpha$), the saturated volumetric water content, the residual volumetric water content, and the saturated hydraulic conductivity. Using the calibrated parameters, the recharge test was simulated. The results of the test and simulation show that the major source of the seepage is the downward groundwater flow through cracks in the protection layer the tombs. It was also analyzed by the steady state simulation that, with a perfect protection layer, a long-term precipitation that, with a perfect protection layer, a long-term precitation could cause only 10% increase of the effective saturation around the north side of the Muryong royal tomb by infiltration of the unsaturated groundwater from the North. Therefore, it is concluded that the most urgent protection plan for the tombs with respect to seepage is to reconstruct an effective waterproof-layer rather than a trenched drainage system.

• Science of Emotion and Sensibility
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• v.2 no.2
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• pp.31-36
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• 1999

본 연구의 목적은 후각 자극에 의한 감성의 변화를 주관적 검사와 동시에 시행한 심전도에서 추출한 HRV parameter와의 상관관계를 보고자 함이다. 후각 자극은 0.6% orange와 2.5% valeric acid를 일정 flow와 일정 농도를 코 점막에 건조를 방지하기 위해 수증기로 포화시킨 향자극기로 주었다. 향의 주관적 검사에서 오렌지향은 친숙하고 쾌하다고 하였으며, valeric acid의 경우 불쾌하고 성가시고 친숙하지 않는 감성을 표시하였다. 이러한 쾌하고 불쾌한 향자극에 대한 HRV 분의 활동이 우세하였음을 확인하였다. 결론적으로 HRV 스펙트럼 분석이 감성의 변화를 객관적인 지표로 나타내는데 유용한 정보로서의 가능성을 제시히고자 하였다.