• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.689-692
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• 2004

Hydrographic data obtained from several ship experiments have shown that internal waves are frequently observed in the East (Japan) Sea, mostly in the continental slopes located along the western side of the East Sea. It is well known that oceanic internal waves can be detected well in synthetic aperture radar (SAR) images. Interactions between surface capillary-gravity waves and horizontally varying surface currents induced by internal waves produce variations in sea surface roughness which can be detected by SAR. C-band SAR images from ERS, ENVISAT ASAR and RADARSAT have been used to study the characteristics of internal waves in the East Sea. The observed properties of internal waves from many SAR images were compared and verified from in-situ measurements and theories.

• Journal of Mechanical Science and Technology
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• v.19 no.5
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• pp.1131-1137
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• 2005

Methods for measuring surface roughness based on light reflectivity have advantages over methods based on light interference or diffraction, especially in in-situ, on-the-machine and in-process applications. However, measurement inconsistencies caused by changes in the specimen are still a drawback for field applications. In this study, we propose a new feedback-based algorithm to enhance the consistency against changes in the specimen. The algorithm is deduced from simulations based on light reflectance theory with typical modeled surfaces. The proposed method is similar to a digital controller and regulates the power of reflected light. Experiments varying heights and materials, verified the improvements in robustness of the method against measurement disturbances caused by specimen changes.

• Journal of the Korean earth science society
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• v.44 no.4
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• pp.264-274
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• 2023

The Korea Strait comprises a continental shelf in a shallow sea that experienced glacio-eustastic sea-level changes during the Quaternary period. A long core of 76.6 m in length was acquired at the South Sea Drilling Project site (SSDP-101; 34°19.666'E and 128°16.335'N) with a 60 m water deep. The uppermost massive sand beds were interpreted as sandy sediments of the nearshore marine sand ridge in the shallow sea during the transgression of sea level, whereas the lower parts of alternating sandy and muddy beds were interpreted as deposits in marsh, estuary, and tidal flat environments. A three-layered geoacoustic model was reconstructed for the sedimentary succession in the high-resolution seismic profile based on a 140-grain size and sediment type of core SSDP-101. For the actual underwater simulation and experiments, the in-situ P-wave speeds were calculated using the sound speed ratio of the Hamilton method.

• Proceedings of the KIEE Conference
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• 2005.07e
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• pp.82-84
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• 2005

In a transformer, thermal stress is the most influential parameter affecting the aging behavior of insulation system. The aging behavior of insulation system in transformer is determined mainly by the thermal conditions inside the transformer. The thermal stress on the insulation system may occur from operation in a high temperature caused by overloading or local overheating. Thus, this paper investigated the condition monitoring of insulation condition in thermally accelerated aged transformer oils by in-situ sensor. The condition of aged samples was investigated by measurements of relative permittivity i.e. capacitance change by capacitive sensor. Results from the experiments are presented in this paper.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.45-48
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• 2001

The packed column experiments were conducted with a field soil, collected directly from the aquifer located at Bonchon industrial complex in K-city in order to characterize SOM reaction with ozone and to delineate the transformation of water soluble SOM after ozonation. As reaction time increased, water soluble organic matter increased, and this organic matter was in the range of 500∼1000 dalton. pH of extractants decreased with the increase of ozonation time. This Is because aromtic compounds in SOM were oxidized and carboxylic acid groups were formed. From the FT-IR spectra, the content of carboxylate increased as ozone injection time increased and hydroxyl group, which represents phenolic and alcoholic hydroxyl groups decreased. This is because oxidative ring fission formed carboxyl acid groups. This result provides a good agreement with pH decrease.

• Bulletin of the Korean Chemical Society
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• v.26 no.3
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• pp.423-427
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• 2005

The bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex-272) and sodium diethyl- dithiocarbamate (NaDDC) ligands were used to extract of metal ions ($Cd^{2+},\;Co^{2+},\;Cu^{2+},\;Pb^{2+},\;Zn^{2+}$) in supercritical $CO_2$. Experiments showed a strong synergistic effect and better extraction efficiency if the two ligands were used together. In-situ UV-visible observation indicates that NaDDC in the water/supercritical $CO_2$ started to decompose slowly. The synergistic effect seems to come from the deprotonation of the organophosphorus ligand by amines from the decomposed NaDDC. The enhancing role of amines was confirmed using the mixture of Cyanex-272 and diethylamine(DEA) in the metal extraction.

• Journal of Power Electronics
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• v.16 no.2
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• pp.695-703
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• 2016

A fuel cell power conditioning system for online diagnosis and load leveling under the condition of varying load is developed in this study. The proposed system comprises a unidirectional boost converter and a bidirectional buck-boost converter with a battery. The system operates in two different modes. In normal mode, the bidirectional converter is utilized for load leveling; in diagnostic mode, it is utilized to control load voltage while the boost converter generates perturbation current to implement the online diagnosis function through in-situ electrochemical impedance spectroscopy (EIS). The proposed method can perform EIS for a fuel cell under varying-load conditions with no influence on the load. The validity and feasibility of the proposed system are verified by experiments, and the design procedure of the proposed system is detailed.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.231-233
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• 2012

Circulating Fluidized Bed (CFB) is a technically and economically proven technology for boiler systems and large CFB coal boilers are making inroads into the domestic power boiler market. For biomass gasification, it is also considered as a very promising technology for commercial. Due to the lack of experiences of a large scale CFB gasifier, however, any large scale CFB gasifiers are hard to in Korea in spite of fast-growing demand of domestic market. In this study, a 3 $MW_{th}$ CFB gasifier was developed for biomass gasification. The CFB gasifier consists of interconnected fast and bubbling fluidized bed reactors including unique features for in-situ tar removal. Various numerical and experimental approaches will be presented such as basic modeling works, investigation of hydrodynamics with a cold model, computational particle fluid dynamics and experiments in the 3 MWth gasifier.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1244-1248
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• 2007

This study aims at investigating the in situ applying grass concrete system in river environments which widely used nowadays and reviewing the effect and flow resistance for grass concrete structure through the physical experiments by hydraulic model test and developing application method in river bed which has rigid flood resistance. Grass concrete structure has been independently tested under high velocity flow under the super critical condition, as well as sud critical flow measuring velocity and water surface elevation along the cross section. This results shows grass concrete system is also suited to use in aggressive river environments such as repairing a flood damaged embankment that had placed at risk the adjacent drainage channel with vegetation.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.5
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• pp.309-312
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• 2003

The transformation capacity (T$\_$c/) of Methylosinus trichosporium OB3b in the degradation of ethylene chlorides was determined by measuring the decrease of soluble methane monooxygenase (sMMO) activity of resting cells in batch experiments. All measurements of sMMO activity were taken in the presence of 20 mM formate to avoid the deficiency of reducing power, and within 2 hrs to avoid the effect of natural inactivation from instability of the resting cells. The constant T$\_$c/ values of 0.58 ${\pm}$ 0.132 and 0.80 ${\pm}$ 0.17 ${\mu}$mol/mg cell were obtained for trichloroethylene (TCE) and 1,2-dichloroethylene (cis and trans-1,2-DCE), respectively, regardless of their concentrations. The transformation capacity measured by this method can be used to predict the amount of cells that should be stimulated in in-situ bioremediation.