• Ocean and Polar Research
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• v.30 no.1
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• pp.21-31
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• 2008

Analyzing the results of East Sea Regional Ocean Model using a 3-dimensional variational data assimilation scheme, we investigated spatial and temporal variability of the North Korean Cold Current (NKCC) in the East Sea. The climatological monthly mean transport of the NKCC clearly shows seasonal variation of the NKCC within the range of about 0.35 Sv ($=0^6m^3/s$), which increases from its minimum (about 0.45 Sv) through December-January to March, decreases during March and May, and then increases again to the maximum (about 0.8 Sv) in August-September. The volume transport of the NKCC shows interannual variation of the NKCC with the range of about 1.0 Sv that is larger than seasonal variation. The southward current of the NKCC appears often not only in summer but in winter as well. The width of the NKCC is about 35 km near the Korean coast and its core is located under the East Korea Warm Current. The North Korean Cold Water (NKCW), characterized by low salinity and low temperature, is located both under the Tsushima Warm Water and in the western side of the maximum southward current of the NKCC that means the NKCC advects the NKCW southward along the Korean coast. It is revealed that the intermediate low salinity water, formed off the Vladivostok in winter, flows southward to the south of $37^{\circ}N$ through $2{\sim}3$ paths; one path along the Korean coast, another one along $132^{\circ}E$, and the middle path along $130^{\circ}E$. The path of the intermediate low salinity varies with years. The reanalysis fields suggest that the NKCW is advected through the paths along the Korean coast and along $130^{\circ}E$.

• Journal of Soil and Groundwater Environment
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• v.10 no.1
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• pp.35-42
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• 2005

This research was investigated the applicability of the biofiltration technology for the removal of volatile organic carbons (VOCs) produced from the bioremediation of oil contaminated soil. Diesel was used as surrogate for oil and, two types of biofilter systems made of ceramic and polymer media were compared for the removal efficiencies of diesel VOCs at different inlet concentrations and space velocity (SV) conditions. During the first 30-d operation, the removal efficiencies of the biofilter packed with polymer and the biofilter packed with ceramic were investigated at constant SV of $153\;h^{-1}$ When inlet concentrations of diesel VOCs were below 10 ppmv, the average removal efficiencies of the polymer biofilter and the ceramic biofilter were average $67\%\;and\;75\%$, respectively. When the inlet concentration increased to 30 ppmv, the VOC removal efficiency in the polymer biofilter was $80\%$, while the average removal efficiency in the ceramic biofilter was $60\%. Effect of the inlet concentration and SV on the removal efficiency of total diesel VOCs was investigated. As SV increased from $153\;h^{-1}$ to $204\;h^{-1}$ and $306\;h^{-1}$, the removal efficiency of total diesel VOCs was decreased gradually. The average removal efficiency of the biofilter packed with polymer carrier was decreased from $82\%\;to\;80\%\;and\;77\%$. The biofilter packed with polymer carrier showed that the removal efficiency of benzene and toluene were maintained within the range of $81\%\~86\%$. In contrast, for the biofilter packed with ceramic carrier, when SV increased from $153\;h^{-1}$ to $204\;h^{-1}$ and $306\;h^{-1}$, the removal efficiency of benzene decreased from $87\%\;to79\%\;and\;74\% . respectively. The removal efficiency of toluene decreased from $80\%\;to\;77\%\;and\;76\%$ at SV of $153\;h^{-1},\;204\;h^{-1}\;and\;306\;h^{-1}$, and $306\;h^{-1}$, respectively.

• The Journal of Engineering Geology
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• v.29 no.4
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• pp.461-468
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• 2019

Gamma-radiation dose rates were measured at 77 points around the Ogcheon lower phyllite zone (og2) in Goesan County, Korea, using gamma-ray spectrometry. Sample K contents were in the range 1.8-8.8% (average 4.6%), highest in Kgr. The eU contents were 0.2-217.9 ppm (average 16.7 ppm), highest in og2 (median 29.6 ppm). The eTh contents were 11.9-76.5 ppm (average 29.5 ppm) and the average eTh content of Kgr was 45.4 ppm, higher than those of Ogcheon meta-sedimentary rocks (og1, og2, and og3) (26.6-30.6 ppm). Except for some high-uranium sites in og2, ⁴⁰K is the main radioactive material contributing to the gamma-radiation dose in the study area. Our results indicate that the outdoor effective dose rate of the area is 0.08-1.71 mSv y^-1 (average 0.28 mSv y^-1), with most areas apart from three points in og2 displaying dose rates <1 mSv y^-1, which is the normal natural radiation background level.

• Journal of Radiation Protection and Research
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• v.27 no.3
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• pp.155-164
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• 2002

Methodology to evaluate the effective doses to adults undergoing various diagnostic x-ray examinations were established by Monte Carlo simulation of the x-ray examinations. Anthropomorphic mathematical phantoms, the MIRD5 male phantom and the ORNL female phantom, were used as the target body and x-ray spectra were produced by the x-ray spectrum generation code SPEC78. The computational procedure was validated by comparing the resulting doses to the results of NRPB studies for the same diagnostic procedures. The effective doses as well as the organ doses due to chest, abdomen, head and spine examinations were calculated for x-rays incident from AP, PA, LLAT and RLAT directions. For instance, the effective doses from the most common procedures, chest PA and abdomen AP, were 0.029 mSv and 0.44 mSv, respectively. The fact that the effective dose from PA chest x-ray is far lower than the traditional value of 0.3 mSv(or 30 mrem), which results partly from the advances of technology in diagnostic radiology and partly from the differences in the dose concept employed, emphasizes necessities of intensive assessment of the patient doses in wide ranges of medical exposures. The methodology and tools established in this study can easily be applied to dose assessments for other radiology procedures; dose from CT examinations, dose to the fetus due to examinations of pregnant women, dose from pediatric radiology.

• Journal of the Korean Magnetics Society
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• v.25 no.5
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• pp.162-168
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• 2015

The ${\mu}$-turn coil having a width of ${\mu}m$ on the GMR-SV (giant magnetoresistance-spin valve) device based on the antiferromagnetic IrMn layer was fabricated by using the optical lithography process. In the case of GMR-SV film and GMR-SV device, the magnetoresistance ratios and the magnetic sensitivities are 4.4%, 2.0%/Oe and 1.6 %, 0.1%/Oe, respectively. In the y-z plane the distribution of magnetic field of GMR-SV device and $10{\mu}$-turns coil which put under the several magnetic bead(MB)s with a diameter of $1{\mu}m$ attached to RBC (red blood cell) was analyzed by the computer simulation using the finite element method. When the AC currents of 20 kHz from 0.1 mA to 10.0 mA flow to the 10 turns ${\mu}$-coil, the magnetic field at the position of $z=0{\mu}m$ at the center of coil was calculated from $30.1{\mu}T$ to $3060{\mu}T$ in proportion to the current. The magnetic field at the position of $z=10{\mu}m$ was decreased to one-sixth of that of $z=0{\mu}m$. It was confirmed that the $10{\mu}$-turn coil having enough magnitude of magnetic field for the capture of RBC is possible to use as a biosensor for the detection of magnetic beads attached to RBC.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.2
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• pp.69-79
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• 2004

In the process of photon treatments, linear accelerators with energies higher than 10 MV produce neutrons through the (${\gamma}$, n) interactions with the composite materials of the linac head md these materials further produce the induced radiations. We investigate the possible risks from these induced radiations especially in the wedge filters to the radiation workers. Wedge filters are used to modify the isodose profiles in the radiation treatment using the linear accelerator and always be handled by the radiation workers. For the background radiation, we measured the radiation in both the waiting room and the outside of the building for two hospitals, S and H. The results of S hospital were $0.11\;{\mu}Sv/hr$ and $0.10\;{\mu}Sv/hr$ for waiting room and outside respectively, and in the case of H hospital, they were $0.12\;{\mu}Sv/hr$ and $0.11\;{\mu}Sv/hr$. Using a survey meter, we measured the radiation from wedge filters inserted in 10 MV and 15 MV Siemens linear accelerators. The time series measurements were done in ${\sim}1$ minutes after exposure of 5 Gy of monitor units for the field size of $25{\times}25cm^2$. The starting value of 10 MV machine was about $3.26\;{\mu}Sv/hr$, which was three times higher than that of 10 MV. The measured radiation was from $^{28}Al$ and $^{53}Fe$ with a half life of 3.5 min. If the treatment patients are $20{\sim}50$ per day and the number of process of wedge filter change per patient is one or two, the annual dose equivalent is $0.08{\sim}0.4\;mSv$ for 10 MV, and $0.27{\sim}1.36\;mSv$ for 15 MV, which are in the range of dose equivalent limits of radiation workers.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.2
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• pp.71-75
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• 1996

A bacterium, capable of the degradation of trimethylamine(TMA), dimethylamine, and methylamine, was isolated from an enrichment culture on TMA basal mineral medium. The isolate was identified as Methylobacterium some carbon-carbon bonds compounds like malate, succinate, betaine. When the strain was immobilized to earthworm cast, the biofilter could remove the gaseous TMA of SV $30h^{-1}$, concentration of 120ppm, continuously.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.757-759
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• 2015

I use a common educational spectrographic device (SV2100R) in order to obtain astronomical spectra after inventing a new adaptor for telescopes. Experimental classes and learning projects in schools and public outreach are well established regarding imaging and photometry observations. However, experiments using astronomical spectrographs are rather hard to find because the procedures of spectral extraction and wavelength calibration is less convenient. SV2100R is a 1D CCD array and thus has the advantage of not requiring spectral extraction. In addition, basic wavelength calibration is preformed by the the provided software. It was adapted to a 12-inch reflecting telescope in the Korea Science Academy of KAIST in Busan and a spectrum of the bright object, Arcturus, was successfully obtained. This means one can provide educational programs on the topic of astronomical spectra. A few suggested projects are presented.

• Food Science and Preservation
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• v.30 no.5
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• pp.758-769
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• 2023

The main aim of this study was to determine python fat's several physicochemical properties, including dimensions, color, structure, acid value (AV), saponification value (SV), density, and recovery efficiency. The optimum yield obtained was approximately 80.40% at 180℃ for 60 min with an AV of 0.3366 and SV of 179.56 mg KOH/g. Fatty acids, comprising oleic acid (72.462%), palmitic acid (26.243%), linolenic acid (0.835%), and myristic acid (0.459%), were identified using gas chromatography-mass spectrometry (GC-MS). The python fat had a very weak antioxidant capacity and almost no antibacterial ability with gram-positive (Staphylococcus aureus - ATCC 25923 and Bacillus cereus - ATCC 10876) and gram-negative (Escherichia coli - ATCC 25922 and Salmonella enterica - ATCC 35664) bacteria (used the paper disc diffusion method for antibiotic susceptibility testing). Moreover, python fat is considered to be very resistant to high temperatures.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.85-90
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• 2010

As the environmental regulation of vehicle emission is strengthened, investigations for $NO_x$ and PM reduction strategies are popularly conducted. Two current available technologies for continuous $NO_x$ reduction onboard diesel vehicles are Selective Catalytic Reduction (SCR) using aqueous urea and lean $NO_x$ trap (LNT) catalysts. The experiments were conducted to investigate the $NO_x$ reduction performance of SCR system which can control the ratio of $NO/NO_2$, temperature and SV(space velocity), and the model gas was used which is similar to a diesel exhaust gas. The maximum reduction efficiency is indicated when the $NO:NO_2$ ratio is 1:1 and the SV is 30,000 $h^{-1}$ in $300^{\circ}C$. Generally, ammonia slip from SCR reactors are rooted to incomplete conversion of $NH_3$ over the SCR. In this research, slip was occurred in 6cases (except low SV and $NO:NO_2$ ratio is 1:1) after SCR. Among 6 case of slip occurrence, the maximum conversion efficiency is observed when SV is 60,000 $h^{-1}$ in $400^{\circ}C$.