• Korean Journal of Remote Sensing
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• v.28 no.5
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• pp.477-487
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• 2012

Sea surface winds in the sea off the east coast of Korea were derived from L-band ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band Synthetic Aperture Radar) data and their characteristics of errors were analyzed. We could retrieve high-resolution wind vectors off the east coast of Korea including the coastal region, which has been substantially unavailable from satellite scatterometers. Retrieved SAR-wind speeds showed a good agreement with in-situ buoy measurement by showing relatively small an root-mean-square (RMS) error of 0.67 m/s. Comparisons of the wind vectors from SAR and scatterometer presented RMS errors of 2.16 m/s and $19.24^{\circ}$, 3.62 m/s and $28.02^{\circ}$ for L-band GMF (Geophysical Model Function) algorithm 2009 and 2007, respectively, which tended to be somewhat higher than the expected limit of satellite scatterometer winds errors. L-band SAR-derived wind field exhibited the characteristic dependence on wind direction and incidence angle. The previous version (L-band GMF 2007) revealed large errors at small incidence angles of less than $21^{\circ}$. By contrast, the L-band GMF 2009, which improved the effect of incidence angle on the model function by considering a quadratic function instead of a linear relationship, greatly enhanced the quality of wind speed from 6.80 m/s to 1.14 m/s at small incident angles. This study addressed that the causes of wind retrieval errors should be intensively studied for diverse applications of L-band SAR-derived winds, especially in terms of the effects of wind direction and incidence angle, and other potential error sources.

• Clean Technology
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• v.17 no.1
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• pp.48-55
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• 2011

The application of fibrous activated carbon (FAC)-titanium dioxide ($TiO_2$) hybrid system has not been reported yet for the control of malodorous dimethyl sulfide (DMS) at residential environmental levels. Accordingly, the current study was designed not only to characterize this hybrid system using x-ray diffraction method, particulate surface measurement and Fourier transform Infrared (FTIR) method, but also to evaluate its adsorptional photocatalytic activity (APA) for the DMS removal. The physical/surface characteristics of FAC-$TiO_2$ which was prepared in this study suggested that the hybrid material might have certain APA for DMS. The Brunauer-Emmett-Teller (BET) specific area, total pore volume, micropore volume and mesopore volume decreased all as the $TiO_2$ amounts coated on FAC increased, whereas the reverse was true for average pore diameter. $TiO_2$ coated onto FAC did not influence the adsorptional activity of FAC for the DMS input concentration of 0.5 ppm. The APA test of the hybrid material presented that the initial removal efficiencies of DMS were 93, 78, 71 and 57% for the flow rates of 0.5, 1.0, l.5 and 2.0 L/min, respectively, and they decreased somewhat 2 h after the experiment started and kept almost constant for the rest experimental period. Under this pseudo-equilibrium condition, the DMS removal efficiencies were 78, 58, 53 and 36% for the four flow rates, respectively. Meanwhile, there were no significant byproducts observed on the surfaces of the hybrid material. Consequently, this study suggests that, under the experimental conditions used in the present study, the hybrid material can be applied for DMS at residential environment levels without being interfered by any byproducts.

• Korean Journal of Remote Sensing
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• v.33 no.2
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• pp.243-248
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• 2017

Sea ice which is an important component of the global climate system is being actively detected by satellite because it have been distributed to polar and high-latitude region. and the sea ice detection method using satellite uses reflectance and temperature data. the sea ice detection method of Moderate-Resolution Imaging Spectroradiometer (MODIS), which is a technique utilizing Ice Surface Temperature (IST) have been utilized by many studies. In this study, we propose a simple and effective method of sea ice detection using the dynamic threshold technique with no IST calculation process. In order to specify the dynamic threshold, pixels with freezing point of MODIS IST of 273.0 K or less were extracted. For the extracted pixels, we analyzed the relationship between MODIS IST, MODIS $11{\mu}m$ channel brightness temperature($T_{11{\mu}m}$) and Brightness Temperature Difference ($BTD:T_{11{\mu}m}-T_{12{\mu}m}$). As a result of the analysis, the relationship between the three values showed a linear characteristic and the threshold value was designated by using this. In the case ofsea ice detection, if $T_{11{\mu}m}$ is below the specified threshold value, it is detected as sea ice on clear sky. And in order to estimate the performance of the proposed sea ice detection method, the accuracy was analyzed using MODIS Sea ice extent and then validation accuracy was higher than 99% in Producer Accuracy (PA).

• Economic and Environmental Geology
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• v.43 no.2
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• pp.109-121
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• 2010

The bioleaching experiment under $42^{\circ}C$ was effectively carried out to leach the more valuable element ions from the pyrite in the Gangyang mine waste. Bacteria can survive at this temperature, as indigenous acidophilic bacteria were collected in the Hatchobaru acidic hot spring, in Japan. To enhance the bacterial activity, yeast extract was added to the pyrite-leaching medium. The indigenous acidophilic bacteria appeared to be rod-shaped in the growth-medium which contained elemental sulfur and yeast extract. The rod-shaped bacteria ($0.7\times2.6\;{\mu}m$, $0.6\times7\;{\mu}m$, $0.8\times5\;{\mu}m$ and $0.7\times8.4\;{\mu}m$) were attached to the pyrite surface. The colonies of the rod-shaped bacteria were selectively attached to the surroundings of a hexagonal cavity and the inner wall of the hexagonal cavity, which developed on a pyrite surface. Filament-shaped bacteria ranging from $4.92\;{\mu}m$ to $10.0\;{\mu}m$ in length were subsequently attached to the surrounding cracks and inner wall of the cracks on the pyrite surface. In the XRD analysis, the intensity of (111), (311), (222) and (320) plane on the bacteria pyrite sample relatively decreased in plane on the control pyrite sample, whereas the intensity of (200), (210) and (211) increased in these samples. The microbiological leaching content of Fe ions was found to be 3.4 times higher than that of the chemical leaching content. As for the Zn, microbiological leaching content, it was 2 times higher than the chemical leaching content. The results of XRD analysis for the bioleaching of pyrite indicated that the indigenous acidophilic bacteria are selectively attacked on the pyrite specific plane. It is expected that the more valuable element ions can be leached out from the mine waste, if the temperature is increased in future bioleaching experiments.

• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.455-464
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• 2012

This study suggested evaluation of approximately exposure to low-dose ionization radiation from medical images using a computed radiography (CR) system in standard X-ray examination and experimental model can compare diagnostic reference level (DRL) will suggest on optimization condition of guard about medical radiation of low dose space. Entrance surface dose (ESD) cross-measuring by standard dosimeter and optically stimulated luminescence dosimeters (OSLDs) in experiment condition about tube voltage and current of X-ray generator. Also, Hounsfield unit (HU) scale measured about each experiment condition in CR system and after character relationship table and graph tabulate about ESD and HU scale, approximately radiation dose about head, neck, thoracic, abdomen, and pelvis draw a measurement. In result measuring head, neck, thoracic, abdomen, and pelvis, average of ESD is 2.10, 2.01, 1.13, 2.97, and 1.95 mGy, respectively. HU scale is $3,276{\pm}3.72$, $3,217{\pm}2.93$, $2,768{\pm}3.13$, $3,782{\pm}5.19$, and $2,318{\pm}4.64$, respectively, in CR image. At this moment, using characteristic relationship table and graph, ESD measured approximately 2.16, 2.06, 1.19, 3.05, and 2.07 mGy, respectively. Average error of measuring value and ESD measured approximately smaller than 3%, this have credibility cover all the bases radiology area of measurement 5%. In its final analysis, this study suggest new experimental model approximately can assess radiation dose of patient in standard X-ray examination and can apply to CR examination, digital radiography and even film-cassette system.

• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.122-134
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• 2015

This study was conducted to investigate the potential of torrefied larch wood as a raw material of pellets. First of all, larch chip was torrefied at the temperatures of 230, 250 and $270^{\circ}C$ for 30, 50 and 70 min. Secondly, moisture content, moisture absorption, higher heating value and ash content of the torrefied chip were measured to examine the effects of torrefaction conditions on the fuel characteristics of larch. Thirdly, surfaces of the torrefied chip were observed by light microscope (LM), field emission scanning microscope (FE-SEM) and SEM-energy dispersive spectroscopy (EDXS). With the increases of torrefied temperature and time, contents of lignin increased and those of hemicellulose reduced. Moisture content of torrefied larch chip was greatly lower than that of non-torrefied chip. Moisture absorption of the torrefied chip decreased as torrefaction temperature increased. As torrefaction temperature increased, higher heating value and ash content of larch chip increased. However, durability of torrefied-larch pellets was remarkably lower comparing to non-torrefied-larch pellets. When surface of larch chip was observed by LM and FE-SEM, surface color and cell wall of the chip was getting darker and more collapsed with the increases of torrefaction conditions. Through the analysis of SEM-EDXS, distribution and quantity of lignin existing on the surface of larch chip increased with the increases of torrefied conditions. In conclusion, $270^{\circ}C$/50 min might be an optimal condition for the torrefaction of larch with the aspect of fuel characteristics, but torrefaction condition of $230^{\circ}C$/30 min should be considered according to the durability of torrefied-larch pellets.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.4
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• pp.875-884
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• 2000

Sea fog/stratus is very difficult to detect because of the characteristics of air-sea interaction and locality ,and the scantiness of the observed data from the oceans such as ships or ocean buoys. The aim of our study develops new algorism for sea fog detection by using Geostational Meteorological Satellite-5(GMS-5) and suggests the technics of its continuous detection. In this study, atmospheric synoptic patterns on sea fog day of May, 1999 are classified; cold air advection type(OOUTC, May 10, 1999) and warm air advection type(OOUTC, May 12, 1999), respectively, and we collected two case days in order to analyze variations of water vapor at Osan observation station during May 9-10, 1999.So as to detect daytime sea fog/stratus(OOUTC, May 10, 1999), composite image, visible accumulated histogram method and surface albedo method are used. The characteristic value during day showed A(min) .20% and DA < 10% when visible accumulated histogram method was applied. And the sea fog region which is detected is similar in composite image analysis and surface albedo method. Inland observation which visibility and relative humidity is beneath 1Km and 80%, respectively, at OOUTC, May 10,1999; Poryoung for visble accumulated histogram method and Poryoung, Mokp'o and Kangnung for surface albedo method. In case of nighttime sea fog(18UTC, May 10, 1999), IR accumulated histogram method and Maximum brightness temperature method are used, respectively. Maxium brightness temperature method dectected sea fog better than IR accumulated histogram method with the charateristic value that is T_max < T_max_trs, and then T_max is beneath 700hPa temperature of GDAPS(Global Data Assimilation and Prediction System). Sea fog region which is detected by Maxium brighness temperature method was similar to the result of National Oceanic and Atmosheric Administratio/Advanced Very High Resolution Radiometer (NOAA/AVHRR) DCD(Dual Channel Difference), but usually visibility and relative humidity are not agreed well in inland.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.781-788
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• 2021

Due to the high sensitivity to radiation, excessive exposure needs to be prevented by accurately measuring the dose irradiated to the skin during radiation therapy. Although clinical trials use dosimeters such as film, OSLD, TLD, glass dosimeter, etc. to measure skin dose, these dosimeters have difficulty in accurate dosimetry on skin curves. In this study, to solve these problems, we developed a skin dosimeter that can be attached according to human flexion and evaluated its response characteristics. For the manufacture of the dosimeter, lead oxide (PbO) with high atomic number (Z_Pb: 82, Z_O: 8) and density (9.53 g/cm³) and silicon binders that can bend according to human flexion were used. In the case of a dosimeter made of PbO material, the performance degradation has been prevented by using parylene and others due to the presence of degradation due to oxidation, but the previously used parylene is affected by bending, so a new form of passive layer was produced and applied to the skin dosimeter. The characteristic evaluation of the skin dosimeter was evaluated by analyzing SEM, reproducibility, and linearity. Through SEM analysis, bending was evaluated, reproducibility and linearity at 6 MeV energy were evaluated, and applicability was assessed with a skin dosimeter. As a result of observing the dosimeter surface through SEM analysis, the parylene passive layer PbO dosimeter with the positive layer raised to the parylene produced cracks on the surface when bent. On the other hand, no crack was observed in the silicon passive layer PbO dosimeter, which was raised to silicon passive layer. In the reproducibility measurement results, the RSD of the silicon passive layer PbO dosimeter was 1.47% which satisfied the evaluation criteria RSD 1.5% and the linearity evaluation results showed the R² value of 0.9990, which satisfied the evaluation criteria R² 9990. The silicon passive layer PbO dosimeter was evaluated to be applicable to skin dosimeters by demonstrating high signal stability, precision, and accuracy in reproducibility and linearity, without cracking due to bending.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.1
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• pp.1-13
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• 2006

A field survey on the spatio-temporal distribution characteristics and origins of organic matter in surface sediments was carried out monthly at six stations in Gamak Bay, South Korea from April 2000 to March 2002. The range of ignition loss(IL) was $4.6{\sim}11.6%(7.1{\pm}1.6%)$, while chemical oxygen demand(CODs) ranged from $12.25{\sim}99.26mgO_2/g-dry(30.98{\pm}19.09mgO_2/g-dry)$, acid volatile sulfide(AVS) went from no detection(ND)${\sim}10.29mgS/g-dry(1.02{\pm}0.58mgS/g-dry)$, and phaeopigment was $6.84{\sim}116.18{\mu}g/g-dry(23.72{\pm}21.16{\mu}g/g-dry)$. The ranges of particulate organic carbon(POC) and particulate organic nitrogen(PON) were $5.45{\sim}23.24 mgC/g-dty(10.34{\pm}4.40C\;mgC/g-dry)$ and $0.71{\sim}2.99mgN/g-dry(1.37{\pm}0.58mgN/g-dry)$, respectively. Water content was in the range of $43.1{\sim}77.6%(55.8{\pm}5.6%)$, and mud content(silt+clay) was higher than 95% at all stations. The spatial distribution of organic matter in surface sediments was greatly divided between the northwestern, central and eastern areas, southern entrance area from the distribution characteristic of their organic matters. The concentrations of almost all items were greater at the northwestern and southern entrance area than at the other areas in Gamak Bay. In particular, sedimentary pollution was very serious at the northwestern area, because the area had an excessive supply of organic matter due to aquaculture activity and the inflow of sewage from the land. These materials stayed longer because of the topographical characteristics of such as basin and the anoxic conditions in the bottom seawater environment caused by thermocline in the summer. The tendency of temporal change was most prominently in the period of high-water temperatures than low-water ones at the northwestern and southern entrance areas. On the other hand, the central and eastern areas did not show a regular trend for changing the concentrations of each item but mainly showed a higher tendency during the low-water temperatures. This was observed for all but AVS concentrations which were higher during the period of high-water temperature at all stations. Especially, the central and eastern areas showed a large temporal increase of AVS concentration during those periods of high-water temperature where the concentration of CODs was in excess of $20mgO_2/g-dry$. The results show that the organic matters in surface sediments in Gamak Bay actually originated from autochthonous organic matters with eight or less in average C/N ratio including the organic matters generated by the use of ocean, rather than terrigenous organic matters. However, the formation of autochthonous organic matter was mainly derived from detritus than living phytoplankton, indicated the results of the POC/phaeopigment ratio. In addition, the CODs/IL ratio results demonstrate that the detritus was the product of artificial activities such as dregs feeding and fecal pellets of farm organisms caused by aquaculture activities rather than the dynamic of natural ocean activities.

• Korean Journal of Heritage: History & Science
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• v.42 no.1
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• pp.122-142
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• 2009

This study explored all domestic and international theories for maintenance and health enhancement of an old and big tree, and carried out the anatomical survey of the operation part of the tree toward he current status of domestic surgery and the perception survey of an expert group, and drew out following conclusion through the process of suggesting its reform plan. First, as a result of analyzing the correlation of the 67 subject trees with their ages, growth status. surroundings, it revealed that they were closely related to positional characteristic, damage size, whereas were little related to materials by fillers. Second, the size of the affected part was the most frequent at the bough sheared part under $0.09m^2$, and the hollow size by position(part) was the biggest at 'root + stem' starting from the behind of the main root and stem As a result of analyzing the correlation, the same result was elicited at the group with low correlation. Third, the problem was serious in charging the fillers (especially urethane) in the big hollow or exposed root produced at the behind of the root and stem part, or surface-processing it. The benefit by charging the hollow part was analyzed as not so much. Fourth, the surface-processing of fillers currently used (artificial bark) is mainly 'epoxy+woven fabric+cork', but it is not flexible, so it has brought forth problems of frequent cracks and cracked surface at the joint part with the treetextured part. Fifth, the correlation with the external status of the operated part was very high with the closeness, surface condition, formation of adhesive tissue and internal survey result. Sixth, the most influential thing on flushing by the wrong management of an old and big tree was banking, and a wrong pruning was the source of the ground part damage. In pruning a small bough can easily recover itself from its damage as its formation of adhesive tissue when it is cut by a standard method. Seventh, the parameters affecting the times of related business handling of an old and big tree are 'the need of the conscious reform of the manager and related business'. Eighth, a reform plan in an institutional aspect can include the arrangement of the law and organization of the old and big tree management and preservation at an institutional aspect. This study for preparing a reform plan through the status survey of the designated old and big tree, has a limit inducing a reform plan based on the status survey through individual research, and a weak point suggesting grounds by any statistical data. This can be complemented by subsequent studies.