• Journal of IKEEE
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• v.21 no.4
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• pp.408-411
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• 2017

In this paper, we propose an integrated control system that measures neutrons, gamma ray, and x-ray. The proposed system is able to monitor and control the data measured and analyzed on the remote or network, and can monitor and control the status of each part of the system remotely without remote control. The proposed system consists of a gamma ray/x-ray sensor part, a neutron sensor part, a main control embedded system part, a dedicated display device and GUI part, and a remote UI part. The gamma ray/x-ray sensor part measures gamma ray and x-ray of low level by using NaI(Tl) scintillation detector. The neutron sensor part measures neutrons using Proportional Counter Detector(low-level neutron) and Ion Chamber Type Detector(high-level neutron). The main control embedded system part detects radiation, samples it in seconds, and converts it into radiation dose for accumulated pulse and current values. The dedicated display device and the GUI part output the radiation measurement result and the converted radiation amount and radiation amount measurement value and provide the user with the control condition setting and the calibration function for the detection part. The remote UI unit collects and stores the measured values and transmits them to the remote monitoring system. In order to evaluate the performance of the proposed system, the measurement uncertainty of the neutron detector was measured to less than ${\pm}8.2%$ and the gamma ray and x-ray detector had the uncertainty of less than 7.5%. It was confirmed that the normal operation was not less than ${\pm}15$ percent of the international standard.

• International Journal of Air-Conditioning and Refrigeration
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• v.9 no.1
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• pp.50-57
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• 2001

The thermal performance of cooling towers is affected by the temperature of inlet water, wet bulb temperature of entering air and water-air flow rate. In this stud${\gamma}$, the effects of these variables are simulated using NTU-method and experimentally investigated for the counter-flow cooling towers. The simulation program to evaluate these variables which affect the performance of cooling tower was developed. The maximum errors between the results of simulations and experiments were 3.8% under the standard design conditions and 5.4% under the other conditions. The performance was increased up to 46~50% as the water loading was increased from 6.8$m^3/hr{\cdot}m^2$ to 159$m^3/hr{\cdot}m^2$. The range was reduced up to 56~42% when the wet bulb temperature of the entering air was increased from 22${\circ}C$ to 29${\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.86-89
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• 2002

We give pressure stimulation into organic thin films and then manufacture a device under the accumulation condition that the state surface pressure is 10[mN/m]. In processing of a device manufacture, we can see the process is good from the change of a surface pressure for organic thin films and transfer ratio of area per molecule. The structure of manufactured device is Au/Poly-${\gamma}$ Benzyl $_D$-Glutamate/Al and Au/Poly-${\gamma}$ Benzyl $_D$-Glutamate/Au; the number of accumulated layers is 1, 3, 5 and 7. Also, we then examined of the MIM device by means of I-V. The I-V characteristic of the device is measured from 0 to +2[V]. We determined electrochemical measurement by using cyclic voltammetry with a three-electrode system. LB film accumulated by monolayer on an ITO. In the cyclicvoltammetry, An Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode measured in $LiBF_4$ solution, stable up to 0.9V vs. Ag/AgCl.

• Journal of Radiation Protection and Research
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• v.34 no.1
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• pp.9-14
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• 2009

High density polyethylene (HDPE) is degraded due to a radiation-induced oxidation when it is used as a neutron moderator in a neutron counter for a nuclear material accounting of spent fuels. The HDPE exposed to the gamma-ray emitted from the fission products in a spent nuclear fuel results in a radiation-induced degradation which changes its original molecular structure to others. So a neutron moderating power variation of HDPE, irradiated by a gamma radiation, was investigated in this work. Five HDPE moderator structures were exposed to the gamma radiation emitted from a $^{60}Co$ source to a level of $10^5-10^9$ rad to compare their post-irradiation properties. As a result of the neutron measurement test with 5 irradiated HDPE structures and a neutron measuring system, it was confirmed that the neutron moderating power for the $10^5$ rad irradiated HDPE moderator revealed the largest decrease when the un-irradiated pure one was used as a reference. It implies that a neutron moderating power variation of HDPE is not directly proportional to the integrated gamma dose rate. To clarify the cause of these changes, some techniques such as a FTIR, an element analysis and a densitometry were employed. As a result of these analyses, it was confirmed that the molecular structure of the gamma irradiated HDPEs had partially changed to others, and the contents of hydrogen and oxygen had varied during the process of a radiation-induced degradation. The mechanism of these changes cannot be explained in detail at present, and thus need further study.

• Journal of Radiation Protection and Research
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• v.45 no.2
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• pp.76-80
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• 2020

Background: To improve the measurement accuracy of liquid-scintillation counting for activity standardization, it is necessary to significantly reduce the background caused by thermal noise or after-pulses. We have therefore improved a movable 3 photomultiplier (3PM)-γ coincidence-counting method using the logical sum of three double coincidences for β events. Materials and Methods: We designed a new data-acquisition system in which β events are obtained by counting the logical sum of three double coincidences. The change in β-detection efficiency can be derived by moving three photomultiplier tubes sequentially from the liquid-scintillation vial. The validity of the method was investigated by activity measurement of ¹³⁴Cs calibrated at the Korea Research Institute of Standards and Science (KRISS) with 4π(PC)β-γ(NaI(Tl)) coincidence counting using a proportional counter (PC) for the β detector. Results and Discussion: Measurements were taken over 14 counting intervals for each liquidscintillation sample by displacing three photomultiplier tubes up to 45 mm from the sample. The dead time in each β- and γ-counting channel was adjusted to be a non-extending type of 20 ㎲. The background ranged about 1.2-3.3 s^-1, such that the contributions of thermal noise or after-pulses were negligible. As the β-detection unit was moved away from the sample, the β-detection efficiencies varied between 0.54 and 0.81. The result obtained by the method at the reference date was 396.3 ± 1.7 kBq/g. This is consistent with the KRISS-certified value of 396.0 ± 2.0 kBq/g within the uncertainty range. Conclusion: The movable 3PM-γ method developed in the present work not only succeeded in reducing background counts to negligible levels but enabled β-detection efficiency to be varied by a geometrical method to apply the efficiency extrapolation method. Compared with our earlier work shown in the study of Hwang et al. [2], the measurement accuracy has much improved. Consequently, the method developed in this study is an improved method suitable for activity standardization of β-γ emitters.

• 대한핵의학회:학술대회논문집
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• 2000.05a
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• pp.74-74
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• 2000

• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.183-187
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• 2003

Collimator for $M{\ddot{o}}ssbauer$ source was manufactured for compton scattering experiment. Exposure dose rate was calculated and measured using GM counter for radiation evaluation. These results were well agreed to each other and used for collimator design. SUS303 was used for collimator material because exposure dose rate at 10 cm is about 2 mR/h. The radiation emited from the 35 mm, 65 mm hole was measured using gamma camera which have 4' diameter. 2-D radiation image was acquired and analyzed. The radiation size at Gamma Camera was 8.0 mm and 5.8 mm respectively.

• Journal of Radiation Protection and Research
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• v.10 no.2
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• pp.130-136
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• 1985

The activity measurement of a solution of $^{133}Ba$ which is an electron capture nuclide was carried out by the ${\beta}-{\gamma}$ coincidence method. The counting rates at the ${\beta}-,\;{\gamma}-$, and coincidence-channels were measured using a $4{\pi}$ proportional counter and two NaI(Tl) scintillation detectors. The specific activity of the solution calculated by the efficiency extrapolation was $(1151.01{\pm}2.99)kBqg^{-1}$ at the reference time(00h UT, 03-15-84). According to an international comparison of activity measurements organized by the Bureau International des Poids et Mesures, this result showed the difference of 0.94% to the mean value derived from the comparison.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.379-384
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• 2011

The critical micelle concentration (CMC) and the counter ion binding constant (B) for the mixed micellizations of DBS (sodium dodecylbenzenesulfonate), SDS (sodium dodecylsulfate), and Brij 30 (polyoxyethylene(4) lauryl ether) at $25^{\circ}C$ in pure water were determined by the use of electric conductivity and surface tension measuring methods. Various thermodynamic parameters ($X_i,\;{\gamma}i,\;C_i,\;a_i^M,\;{\beta}$, and ${\Delta}H_{mix}$) were calculated and compared with each other mixed surfactant system by means of the equations derived from the nonideal mixed micellar model. The results show that the SDS molecule interacts more strongly with Brij 30 molecule than DBS molecule and that the SDS/Brij 30 mixed surfactant system has the greatest negative deviation from the ideal mixed micellar model and the SDS/DBS mixed system has followed almost the ideal mixed micellar model.

• Journal of the Korean Chemical Society
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• v.53 no.5
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• pp.491-498
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• 2009

The critical micelle concentration (CMC) and the counter ion binding constant (B) for the mixed micellizations of DBS (sodium dodecylbenzenesulfonate) with Brij 30 (polyoxyethylene(4) lauryl ether) and Brij 35 (polyoxyethylene (23) lauryl ehter) at 25 ${^{\circ}C}$ in pure water and in aqueous solutions of n-butanol were determined as a function of $\alpha$1 (the overall mole fraction of DBS) by the use of electric conductivity method. Various thermodynamic parameters (Xi, $\gamma$i, Ci, aiM, $\beta$, and ${\Delta}H_{mix}$) were calculated and compared for each mixed surfactant system by means of the equations derived from the nonideal mixed micellar model. There sults show that the molecules of DBS interact more strongly with Brij 35 than Brij 30 and that the DBS/Brij35 mixed system has greater negative deviation from the ideal mixed micellar model than the DBS/Brij 30mixed system.