• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.11 no.1
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• pp.8-14
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• 1975

The optical properties of the sea water were studied by use of underwater lux-meters in the coastal waters of Busan from May to November 1975. The absorption coefficient of the sea water in the area ranges from O. 169 to 1. 049 and the mean absorpflOn coefficient is 0.413. Maximum monthly mean absorption coefficient (0. 56) was observed in August, while the minimum was O. 338 in September. There was a distinct discontinuity layer of the absorption coefficient in accordance with the thermocline and the halocline in summer. The mean transparency of the area was 3. 8 meters, and transparency in autumn was higher than that in summer. The relation between absorption coefficient (m) and transparency (D) was deduced, m=1. 57/ D. The rate of light penetration at 5 m-layer of sea water was 2. 5 percent when the solar altitude was six degree in July 1975.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.2
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• pp.174-179
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• 2012

A new absorption material, cellulose sponge soaked in cement, was made for anechoic water tank and its acoustical properties were investigated by pulse methods. The sound absorption coefficient a (dB/cm) of the material was obtained in the frequency range of 40~120kHz from the echo reduction ER (dB) and insertion loss IL (dB) data. The result was averagely 1.8dB/cm higher than the sound absorption coefficient a (dB/cm) of cork-filled rubber which is one of the most effective absorption materials. The wedge (1.2~5.0cm long) type absorption tiles were made with this new material. The echo reduction ER (dB) of the absorption tile with 5.0cm wedge measured in water tank was higher than 20dB in the experimental frequency range.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.6
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• pp.782-791
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• 1998

This paper presents a computer simulation of five types of triple effect absorption cycles employ-ing the refrigerant absorbent combinations of NH3/LiNO3 low-pressure type NH3/LiNO3+H2O/LiBr binary two-stage type series flow cycle and two types of parallel flow cycle for H2O/LiBr. The absorption systems is investigated through cycle simulation to obtain the system characteristics with the cooling water inlet temperature approach temperature of absorber loss temperature of absorber and chilled water outlet temperature. The most important characteristic temperature of absorber and chilled water outlet temperature. The most important characteristic of NH3/LiNO3 low-pressure type and a NH3/LINO3+H2O/LiBr binary two-stage type is that it obtains a coefficient of performance higher than the sum of the performance coefficients of its part operating independently. As a result of this analysis the optimum designs and operating conditions were determined based on the operating conditions and the coefficient of performance.

• Journal of the Korean Society of Radiology
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• v.16 no.1
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• pp.61-66
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• 2022

The purpose of this study is to derive photon energy fluence and mass energy absorption coefficient for 1 Gy of absorbed dose of water in brachytherapy using an Ir¹⁹² source. From the radiotherapy physics written by Khan, the half-value of lead for the gamma ray beam of the Ir¹⁹² source was obtained. The linear attenuation coefficient and the mass attenuation coefficient were calculated from the obtained half-value layer of lead. By matching the calculated lead mass attenuation coefficient with the NIST mass attenuation coefficient data, the photon energy of the matching mass attenuation coefficient was determined as the effective energy. By matching the determined effective energy with the photon energy of the NIST data on the mass energy absorption coefficient of water, the mass energy absorption coefficient of water was obtained as 0.03273 cm²/g(32.73 cm²/kg). The photon energy fluence was calculated as 0.03055 J/cm² by dividing the obtained mass energy absorption coefficient (32.73 cm²/kg) by the absorbed dose of water 1 Gy.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.3
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• pp.267-276
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• 2000

A numerical study has been carried out to find out the optimal design condition of a solar absorption cooling system. The system was composed of solar collectors and an absorption chiller with LiBr/water The System performance with commercial single effect(SE) cycle and a new single effect/double lift(SE/DL) cycle utilizing low temperature hot water was calculated and compared. It was found that the required solar collector area grew exponentially as the overall heat loss coefficient of solar collectors increased. For instance, the required area for cooling capacity of 1 USRT was $17m^2$ if heat loss coefficient was 4 W/$m^2\;cdot\;K$. If heat loss coefficient was doubled($8\;W/m^2\;cdot\;$K), the required collector area was increased by 6 times($100m^2$) .It was also found that the SE-cycle as the heat loss coefficient of solar collectors increased. Generally, a SE/DL-cycle seems to be more advantageous than a SE-cycle if loss coefficient of solar collector is greater than 4 W/$m^2\;cdot\;K$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.3
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• pp.422-430
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• 1999

This paper concerns the study of a two-stage absorption heat pump cycle to utilize treated sewage. This two-stage cycle consists of coupling double-effect with parallel or series flow type and single effect cycle so that the first stage absorber and condenser produces hot water to evaporate refrigerant in the evaporator of the second stage. The effects of operating variables such as absorber temperature on the coefficient of performance have been studied for two-stage absorption heat pump cycle. The working fluid is lithium bromide and water solution. The efficiency of the two-stage absorption heat pump cycle has been studied and simulation results show that higher coefficient of performance could be obtained for the first stage with parallel flow type. The optimum ratio of solution distribution can be shown by considering the COP, the crystallization of solution and the generator temperature.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1321-1335
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• 2022

This study was conducted to investigate the effect of absorption coefficient models on the P1 radiation model for a premixed hydrogen flame containing the water vapor. A CFD combustion simulation analysis was performed using XiFoam, one of the open-source CFD solvers in OpenFOAM. The solver using the flamelet combustion model has been modified to implement radiative heat transfer. The absorption coefficient models used in this study the grey-mean model and constant model, and for comparison, case without radiation was added. This CFD simulation study consisted of benchmarking the THAI HD-15 and HD-22 experiments. The difference between the two tests is the inclusion of water vapor in the condition before ignition. In the case of the HD-22 experiment containing water vapor in the initial condition, the simulation results show that the grey-mean absorption coefficient model has a strong influence on the temperature decrease of the flame and on the change in pressure inside the vessel.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.3
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• pp.113-120
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• 2000

On the absorber of absorption chiller/heater, LiBr solution at high concentration is sprinkled on a bundle of horizontal tube cooled by cooling water. In this case, the conditions of LiBr solution and cooling water have an influence on heat/mass transfer coefficient in this system. Therefor it is important to find optimal operation conditions of absorption chiller/heater to save energy. Heat and mass transfer coefficient increased with the increase of solution flow rate, and also heat and mass transfer rate increased but overall heat and mass transfer coefficient decreased by increasing the solution concentration within the experimental range. The superheating of the solution resulted in superior heat transfer character to a state of equilibrium from the point of heat flux and overall heat transfer coefficient.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.103.2-108
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• 2003

The purpose of this study is to understand the Physical characteristics of cement mortar about humidity control on indoors and wall crack restraint. Experiments were conducted on the strength, water absorption coefficient, drying-shrinking crack, length change, cracks of mortar plaster bases according to mixture rate by mixing cellulose fiber and diatomite into cement mortar. The excellent tensile & bending reinforcement efficiency of cellulose fiber and void filling ability of diatomite proved to be suppressing cracks of cement. And diatomite seems to improve moisture-protection efficiency of cement mortar because of its high water absorption ratio and slow drying speed.

• Proceedings of the KSRS Conference
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• v.1
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• pp.495-498
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• 2006

Optical profile and spectral absorption of suspended solids in waters of Sanya bay was measured on August 8-14, 2003. Optical profile was taken by using MicroPro optical profile. Apparent optical indexes, vertical diffuse attenuation coefficient ($K_d$) and water leaving radiance (Lw), were calculated. $K_d$ at the blue end of the spectrum was greater than that at the red end of the spectrum in waters near Sanya River mouth, however, in waters near open sea, $K_d$ at the blue end of the spectrum was smaller than that at the red end of the spectrum. Distribution of water leaving radiance was relatively higher in waters near Sanya River mouth, but relatively weaker in near open sea water. Spectral absorption of suspended particulates was also measured. Results showed that the spectral absorption of chlorophyll a was greater in waters near Sanya river mouth, but relatively weaker in waters near open sea, which indicated higher concentration of phytoplankton in waters near Sanya river mouth. Except for water at the 5th sampling station, the ratio of spectral absorption of chlorophyll a to total suspended particulates in surface waters was greater than that in bottom waters at all stations.