• Journal of Radiation Protection and Research
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• v.24 no.4
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• pp.215-223
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• 1999

Characteristics of radiation field in the steam generator(S/G) water chamber of a PWR were investigated and the anticipated effective dose rates to the worker in the S/G chamber were evaluated by Monte Carlo simulation. The results of crud analysis in the S/G of the Kori nuclear power plant unit 1 were adopted for the source term. The MCNP4A code was used with the MIRD type anthropomorphic sex-specific mathematical phantoms for the calculation of effective doses. The radiation field intensity is dominated by downward rays, from the U-tube region, having approximate cosine distribution with respect to the polar angle. The effective dose rates to adults of nominal body size and of small body size(The phantom for a 15 year-old person was applied for this purpose) appeared to be 36.22 and 37.06 $mSvh^{-1}$) respectively, which implies that the body size effect is negligible. Meanwhile, the equivalent dose rates at three representative positions corresponding to head, chest and lower abdomen of the phantom, calculated using the estimated exposure rates, the energy spectrum and the conversion coefficients given in ICRU47, were 118, 71 and 57 $mSvh^{-1}$, respectively. This implies that the deep dose equivalent or the effective dose obtained from the personal dosimeter reading would be the over-estimate the effective dose by about two times. This justifies, with possible under- or over- response of the dosimeters to radiation of slant incidence, necessity of very careful planning and interpretation for the dosimetry of workers exposed to a non-regular radiation field of high intensity.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.4
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• pp.269-278
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• 2005

In order to produce only a pH-controlled solution without discharging any unwanted solution, this work has developed a continuous electrolytic system with a pH-adjustment reservoir being placed before an ion exchange membrane-equipped electrolyzer, where as a target solution was fed into the pH-adjustment reservoir, some portion of the solution in the pH-adjustment reservoir was circulated through the cathodic or anodic chamber of the electrolyzer depending on the type of the ion exchange membrane used, and some other portion of the solution in the pH-adjustment reservoir was discharged from the electrolytic system through the other counter chamber with its pH being controlled. The internal circulation of the pH-adjustment reservoir solution through the anodic chamber in the case of using a cation exchange membrane and that through the cathodic chamber in the case of using an anion exchange membrane could make the solution discharged from the other counter chamber effectively acidic and basic, respectively. The phenomena of the pH being controlled in the system could be explained by the electro-migration of the ion species in the solution through the ion exchange membrane under a cell potential difference between anode and cathode and its consequently-occurring non-charge equilibriums and electrolytic water- split reactions in the anodic and cathodic chambers.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.3
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• pp.182-188
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• 2014

In an oscillating water column (OWC)-type wave energy conversion system, the performance of the OWC chamber depends on the chamber shape, as well as the incident wave direction and pressure drop produced by the turbine. Although the previous studies on OWC chambers have focused on wave absorbing performance in ideal operating conditions, incident waves do not always arrive normally to the OWC chamber in real sea conditions, especially in fixed devices. The present study deals with experiments and numerical calculations to investigate the effects of wave direction on the performance of the OWC chamber. The experiments were carried out in a three-dimensional wave basin for five different wave directions, including the effect of turbine using the corresponding orifice. The wave elevation inside the chamber was measured at the center point under various incident wave conditions. The numerical study was conducted by using a numerical wave tank-based volume-of-fluid model to compare the results with experimental data and to reveal the detailed flows around the chamber.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.151-159
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• 1997

Benthic respiration and chemical fluxes were measured at the sediment-water interface underlying the marine fish cages floating on the open coastal waters off Tong-Young, the South Coast of Korea. The effects of cage farming on coastal benthic environment and on mass balance of organic carbon in the benthic boundary layer under the marine fish cages are addressed. In a growing season of caged fishes of June, 1995, benthic chambers and sediment traps were deployed on the sediment-water interfaces of the two sites chosen for this study: 1) Cage Site, directly underlying the fish cages of the farm at 18 m water depth, and 2) Control Site, about 100 m away from the farm at 32 m water depth. Benthic respiration rates and chemical fluxes were calculated from the evolution of dissolved oxygen and chemicals in the chamber water, and mass balance of organic carbon in the benthic boundary layer was constructed based on the vertical flux of particulate organic matter (POM) and chemical fluxes out of the sediment. High organic dumping (6400 mg C $m^{-2}d^{-1}$) and high benthic respiration (230 mmol $O_2\;m^{-2}d^{-1}$) were observed at the Cage Site. Equivalent to 40% of vertical flux of organic carbon into the Cage Site seemed to be decomposed concurrently and released back to overlying waters (2400 mg C $m^{-2}d^{-1}$). Consequently, up to 4000 mg C $m^{-2}d^{-1}$ of organic carbon could be buried into the farm sediment (equivalent to 60% of organic carbon flux into the Cage Site). At the Control Site, relatively less input of organic carbon (4000 mg C $m^{-2}d^{-1}$) and low benthic respiration rate (75 mmol $O_2\;m^{-2}d^{-1}$) were observed despite short distance away from the cages. The influence of cage farming on benthic chemical fluxes might be restricted and concentrated in the sea bottom just below the fish cages in spite of massive organic dumping and high current regime around the fish cage farm.

• Progress in Medical Physics
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• v.18 no.2
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• pp.87-92
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• 2007

A thermal neutron beam facility utilizing a typical tangential beam port for Neutron Capture Therapy was installed at the HANARO, 30 MW multi-purpose research reactor. Mixed beams with different physical characteristics and relative biological effectiveness would be emitted from the BNCT irradiation facility, so a quantitative analysis of each component of the mixed beams should be performed to determine the accurate delivered dose. Thus, various techniques were applied including the use of activation foils, TLDs and ionization chambers. All the dose measurements were perform ed with the water phantom filled with distilled water. The results of the measurement were compared with MCNP4B calculation. The thermal neutron fluxes were $1.02E9n/cm^2{\cdot}s\;and\;6.07E8n/cm^2{\cdot}s$ at 10 and 20 mm depth respectively, and the fast neutron dose rate was insignificant as 0.11 Gy/hr at 10 mm depth in water The gamma-ray dose rate was 5.10 Gy/hr at 20 mm depth in water Good agreement within 5%, has been obtained between the measured dose and the calculated dose using MCNP for neutron and gamma component and discrepancy with 14% for fast neutron flux Considering the difficulty of neutron detection, the current study support the reliability of these results and confirmed the suitability of the thermal neutron beam as a dosimetric data for BNCT clinical trials.

• Korean Journal of Ichthyology
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• v.27 no.2
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• pp.71-77
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• 2015

Morphological changes in eggs and larvae of spotted knifejaw, Oplegnathus punctatus were observed by cultivation of fertilized eggs to juvenile stage. Fertilized egg was demersal and transparent. The egg has one oil glouble and its size ranged 1.01~1.15 mm ($1.08{\pm}0.10mm$; $mean{\pm}SD$, n=20). Culture chambers were maintained $22.5{\sim}24.5^{\circ}C$ in water temperature and 33.5~34.5ppt in salinity. It took 25 mins from fertilization to the blastoderm stage, 55 mins to 2 cell stage and 20 hrs 50 mins to hatching. Newly hatched yolksac larvae ranged 2.59~3.02 mm ($2.81{\pm}0.25mm$, n=5) in total length, and mouth and anus were not still open. Yolk and oil globule were absorbed 2 days after hatching (DAH). Flexion larvae in 12 DAH ranged 3.02~3.07 mm TL ($3.04{\pm}0.04mm$), and the caudal fin grew to fan-shaped, melanophores appeared on top of digestive canal.

• Journal of Biosystems Engineering
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• v.26 no.3
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• pp.209-220
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• 2001

This study was carried out to investigate the usability of the used frying oil, which was extracted from soybean, as one of the alternative fuel of a small diesel engine. For the experiment, NO. 2 diesel oil [D], used frying oil [UF], and their volumetric blends were applied and analysis of the properties and compositions of the experimental fuels were conducted. A four cycle diesel engine with single cylinder, water cooling system, maximum output 8.1 ㎾/2,200 rpm was selected and a direct injection chamber and a precombustion chamber were attached alternately. The results obtained were as follows: 1. Engine power (BHP) were increased from 4.13~4.27㎾ to 9.08~9.15㎾ for diesel oil, from 4.05~4.19㎾ to 8.44~8.92㎾ for UF, and from 4.01~4.48㎾ to 8.69~9.16㎾ for blend fuel, as the engine speed increased from 1,000 rpm to 2,200 rpm. The BHP in case of the direct combustion chamber were fluctuated higher than those of the pre-combustion chamber. 2. With the engine speed increased, torque of the engine were increased from 39.50~40.80 N.m to 42.89 N.m, then decreased to 39.44~39.77 N.m for diesel oil, and increased from 38.73~40.04 N.m to 40.12~40.82 N.m then decreased as 36.53~38.76 N.m for UF. Torque of the blend fuels were increased from 38.75~41.76 N.m to 40.47~42.89 N.m then decreased to 37.73~39.78 N.m. There is no significant difference of torque between the type of combustion chambers. 3. The specific fuel consumption of the UF was increased about 20 percent depending on the engine speed variations. And in case of direct injection chamber, about 12 percent lower fuel consumption was observed than that of precombustion chamber. 4. NOx emission of the UF was higher than that of diesel oil at above 1,800rpm of the engine speed. In case of the direct injection chamber, NOx emission was revealed higher about 59 percent than that of the precombustion chamber, depending on the range of the engine speeds. 5. Smoke emission was decreased in case of UF compared with diesel oil on direct injection chamber. When using precombustion chamber smoke emission was a little higher than that of the direct injection chamber were showed at the engine speed range. 6. At all the engine speed range, exhaust gas temperatures were decreased 2~3$^{\circ}C$ for UF used engine compared with those of the diesel oil. The exhaust gas temperature of the direct injection chamber was higher than that of the precombustion chamber by 72$^{\circ}C$. 7. Unburnt materials remained in the cylinder in case of the pre-combustion chamber was smaller and softer than that of the direct combustion chamber. 8. The feasibility of the blend fuel B-1 and B-2 were verified as a direct combustion chamber was attached to the diesel engine, with respect to the power performance of the engine.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.3
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• pp.179-185
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• 2005

The effects of $CO_2$ enrichment on growth of rice (Oryza sativa L.) were examined. The plants were grown in growth chambers with a 12-h photoperiod and a day/night temperature of $28/21^{\circ}C$ of the seedling stage and $30/23^{\circ}C$ after the panicle initiation stage. The plants were exposed to two elevated $CO_2$ of 500, 700 ppm and ambient levels (350 ppm). At early growth stage of three varieties (IIpumbyeo, Chucheongbyeo, Hwaseongbyeo), the elevated $CO_2$ increased plant height, tiller, leaf area and dry weight. The photosynthetic rate was decreased at 24 days after treatment (DAT) compared to 11 DAT. The elevated $CO_2$ increased plant height and dry weight at panicle initiation stage (PIS) and heading stage (HS) of three varieties (IIpumbyeo, Chucheongbyeo, Hwaseongbyeo). The photosynthetic rate, stomatal conductance, evapotranspiration rate were decreased at the long days of treatment than that of short days. At entire stages, the elevated $CO_2$ increased the water use efficiency of rice plant because evapotranspiration rate was lowered at the elevated $CO_2$ than ambient levels.

• Ocean and Polar Research
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• v.32 no.1
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• pp.63-71
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• 2010

An experiment was conducted to investigate the effects of temperature and stocking density on daily patterns and rates of total ammonia nitrogen (TAN) excretion in juvenile red seabream Pagrus major (mean body weight: 29.0 g) under fasting and feeding conditions. Fish were acclimated over 7 days under four different temperatures (10, 15, 20, and $25^{\circ}C$) and at two different densities (5.5 and $11.0\;kg\;m^{-3}$). Each treatment had three replicates and a total of 216 fish were used. After 72 hours starvation, endogenous TAN excretion was measured for each temperature and density. To investigate exogenous TAN excretion, fish were handfed a commercial diet containing 51.6% crude protein twice a day for 7 days, at 08:00 and 16:00. Water was sampled from both inlets and outlets of chambers every 2 hours over a 24 hour period. Both endogenous and exogenous TAN excretion increased with increases in temperature and density (P<0.05). Mean daily endogenous TAN excretion rates at 10, 15, 20, and $25^{\circ}C$ were 88.8, 101.1, 125.0, and $143.3\;mg\;TAN\;kg^{-1}\;d^{-1}$ at low density, and 105.2, 119.2, 141.5, and $168.8\;mg\;TAN\;kg^{-1}\;d^{-1}$ at high density, respectively. Mean daily exogenous TAN excretion rates at 10, 15, 20, and $25^{\circ}C$ were 343.5, 403.7, 535.7, and $601.7\;mg\;TAN\;kg^{-1}\;d^{-1}$ at low density, and 391.9, 479.7, 611.9, and $683.4\;mg\;TAN\;kg^{-1}\;d^{-1}$ at high density, respectively. The exogenous TAN excretion rate peaked 10~12 hours after the first feeding under all temperatures and densities. The TAN loss for ingested nitrogen increased with increases in temperature and density (P<0.05), ranging from 27.9 to 50.1% at low density and 31.7 to 56.9% at high density. This study provides empirical data for estimating ammonia excretion and managing the culture of red seabream under the given temperatures and densities.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.1
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• pp.107-114
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• 2005

Soil CO₂ emission is one of the primary components in carbon balance of terrestrial ecosystems. In soil CO₂ flux measurements, chamber method is currently the most common technique. Prior to compare or synthesize the data collected from different chamber methods, potential biases must be quantified for each measurement system. We have conducted an intercomparison experiment among four closed dynamic chamber systems and an automatic open-closed chamber system in a temperature-controlled phytotron. Due to the disturbed CO₂ concentrations inside the phytotron during the measurements with closed dynamic chambers and the changes in soil water content, the interpretation of the data was difficult to quantify the biases of individual methods. However, the experiment provided not only valuable information on the performance characteristics of the five instruments to varying soil temperature and CO₂ concentration but also useful insights for better designs and strategy for future intercomparison in a controlled environment.