Joo Hyun Moon

Gyeongju University, Gyeongju, North Gyeongsang, South Korea

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Publications (31)27.01 Total impact

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    ABSTRACT: A fiber-optic sensor system using a multiplexed array of sensing probes based on an aqueous solution of sodium chloride (NaCl solution) and an optical time-domain reflectometer (OTDR) for simultaneous measurement of temperature and water level is proposed. By changing the temperature, the refractive index of the NaCl solution is varied and Fresnel reflection arising at the interface between the distal end of optical fiber and the NaCl solution is then also changed. We measured the modified optical power of the light reflected from the sensing probe using a portable OTDR device and also obtained the relationship between the temperature of water and the optical power. In this study, the water level was simply determined by measuring the signal difference of the optical power due to the temperature difference of individual sensing probes placed inside and outside of the water. In conclusion, we demonstrate that the temperature and water level can be obtained simultaneously by measuring optical powers of light reflected from sensing probes based on the NaCl solution. It is anticipated that the proposed fiber-optic sensor system makes it possible to remotely monitor the real-time change of temperature and water level of the spent fuel pool during a loss of power accident.
    Sensors 10/2014; 14(10):18823-18836. · 2.05 Impact Factor
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    ABSTRACT: A fiber-optic sensor system using a multiplexed array of sensing probes based on an aqueous solution of sodium chloride (NaCl solution) and an optical time-domain reflectometer (OTDR) for simultaneous measurement of temperature and water level is proposed. By changing the temperature, the refractive index of the NaCl solution is varied and Fresnel reflection arising at the interface between the distal end of optical fiber and the NaCl solution is then also changed. We measured the modified optical power of the light reflected from the sensing probe using a portable OTDR device and also obtained the relationship between the temperature of water and the optical power. In this study, the water level was simply determined by measuring the signal difference of the optical power due to the temperature difference of individual sensing probes placed inside and outside of the water. In conclusion, we demonstrate that the temperature and water level can be obtained simultaneously by measuring optical powers of light reflected from sensing probes based on the NaCl solution. It is anticipated that the proposed fiber-optic sensor system makes it possible to remotely monitor the real-time change of temperature and water level of the spent fuel pool during a loss of power accident.
    Sensors (Basel, Switzerland). 01/2014; 14(10):18823-18836.
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  • Chan Hee Park, Joo Hyun Moon, Bum Kyoung Seo
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    ABSTRACT: In this study, we developed and characterized an integrated fiber-optic sensor for the remote detection of alpha radiation emitted from radioactive contamination in areas relatively inaccessible by radiation workers. The fiber-optic sensor consisted of an epoxy-resin supporter and a sensing probe attached to it. The epoxy-resin supporter to hold the optical fiber tightly was fabricated by using epoxy-resin and a small amount of hardener. The sensing probe was fabricated by mixing epoxy-resin with inorganic scintillator ZnS(Ag) powder and solidifying the mixture. Then, the sensing probe was attached to the epoxy-resin supporter. As a light guide, an optical fiber, which was also compatible with the epoxy-resin, was used. The optical fiber was submerged in the epoxyresin supporter before solidification to make it in an integral form to minimize the loss of scintillation light due to incomplete connections between them. The four assembled fiber-optic sensors with sensing probes whose density thicknesses of ZnS(Ag) were 10, 15, 20 and 25 mg/cm2, respectively, were evaluated in terms of the total counts of alpha radiation to determine the optimum density thickness of ZnS(Ag). From the evaluation, a density thickness of 15 mg/cm2 was found to be the best for detecting alpha radiation.
    Journal- Korean Physical Society 11/2013; 63(9):1720-1723. · 0.43 Impact Factor
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    ABSTRACT: The aim of this study was to survey the radon concentrations at 21 elementary schools in Gyeongju, Republic of Korea, to identify those schools with high radon concentrations. Considering their geological characteristics and the preliminary survey results, three schools were finally placed under close scrutiny. For these three schools, continuous measurements over 48h were taken at the principal's and administration office. The radon concentrations at one school, Naenam, exceeded the action level (148Bq/m(3)) established by the U.S. EPA, while those at the other two schools were below that level.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 04/2013; · 1.09 Impact Factor
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    ABSTRACT: A fiber-optic radiation sensor (FORS), which is composed of an inorganic scintillator, a plastic optical fiber (POF), a photomultiplier tube (PMT), and a multichannel analyzer (MCA), was developed for gamma-ray energy spectroscopy. In this study, we selected a cerium-doped lutetium yttrium orthosilicate (LYSO:Ce) as the sensitive element of the FORS and found that LYSO:Ce with dimensions of 3 × 3 × 15mm3 gives the best performance in obtaining a gammaray energy spectrum. The FORS allows us to measure the energy spectra of Co-60, Na-22, and Cs-137.
    Optical Review 03/2013; 20(2):205-208. · 0.55 Impact Factor
  • Chan Hee Park, Joo Hyun Moon, Bum Kyong Seo
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    ABSTRACT: Measuring the level of radioactive contamination in a high-radiation area with a complex geometry requires a new measuring system that can be operated remotely and free of electronic noise by radiation. In this study, a measuring system suitable for measuring high-level radioactive contamination in the narrow gap of a nuclear facility was developed. The measuring system was a fiber-optic remote system using an organic scintillator, epoxy resin and an optical fiber. The measuring system was tested for Cs-137 and Sr/Y-90 radiation sources, and could measure radioactive contamination remotely in a narrow area.
    Radiation Measurements 08/2011; 46(8):687-693. · 1.14 Impact Factor
  • Kyoung Won Jang, Bong Soo Lee, Joo Hyun Moon
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    ABSTRACT: Sometimes, detection of thermal neutrons in the presence of gamma rays is required. This study developed and characterized an integrated fiber-optic radiation sensor for the simultaneous detection of thermal neutrons and gamma rays in a mixed radiation field. The performance of the integrated sensor was verified by measuring the distributions of thermal neutrons and gamma rays released from a nuclear fuel rod at the Kyoto University Critical Assembly. The experimental results show that the integrated sensor produced similar distribution patterns to those of thermal neutrons and gamma rays released from a fuel rod.
    Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 04/2011; 69(4):711-5. · 1.09 Impact Factor
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    ABSTRACT: A Novel Planar Small Electrode Sensor (NPSES) using the semi-conductor process was developed in this study to find out Acupuncture Points (APs) or Biological Active Points (BAP) on the human being's skin. The NPSES with eight (8) electrodes tracks generates the electrical properties of the BAPs on the skin. These eight tracks are located in a circle of 2 mm diameter. The BAP locations generated by the NPSES are characterized by high electric potential, high electric capacity, and low electric resistance, compared to non-Acupuncture Points (non-APs). The traditional unit applied for the BAP is the cun, the Chinese anatomical inch. The BAPs are distinguished by the difference in voltage between the measurement electrode and the reference one, i.e., the difference in the resistance and reactance of BAPs. The BAP size might be in the range of 1 to 2 mm2. Five (5) healthy human subjects of between 27 and 42 years were examined to investigate the effectiveness of the NPSES for finding out the BAPs. The current and frequency applied to this experiment were in the range of 7.5 A and 0.1 Hz to 1.5 kHz, respectively. We believe that the NPSES system developed in this study is highly reliable for and scientifically applicable to locating the BAPs on the human being's skin.
    Sensor Letters 02/2011; 9(1):218-222. · 0.56 Impact Factor
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    ABSTRACT: In this study, we have fabricated a fiber-optic radiation sensor using an organic scintillator for brachytherapy dosimetry. Organic scintillators are made from a polystyrene base with wavelength-shifting fluors, and they do not disturb the radiation field due to their tissue or water-equivalent characteristics in a wide range of energies. The fiber-optic radiation sensor developed for this study provides a fast real-time response and convenient usage for brachytherapy dosimetry. For more accurate measurement, we have measured Cerenkov light using a dummy fiber and avoided dose measurement errors arising from high dose gradients in brachytherapy dosimetry. The Cerenkov light has been eliminated using a modified subtraction method. Also, the relative depth dose without the dose generated from Cerenkov lights is measured and compared with the results obtained using conventional EBT dosimetry films.
    IEEE Transactions on Nuclear Science 07/2010; · 1.46 Impact Factor
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    Journal- Korean Physical Society 06/2010; 56(6). · 0.43 Impact Factor
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    Journal- Korean Physical Society 03/2010; 56(3):765-769. · 0.43 Impact Factor
  • Byeong Soo Kim, Joo Hyun Moon
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    ABSTRACT: An optimization method based on genetic algorithm (GA), which is referred as MACroscopic Near-Optimal Shielding design (MACNOS), is proposed for the search for an optimal radiation shield configuration subject to a given set of constraints. In MACNOS, a GA is used to search for the optimal shielding design and the penalty strategy is employed to deal with the constraints. In order to confirm its capability to search for the optimal shielding design, MACNOS is applied for solving a simple problem with regard to radiation shielding optimization of a hypothetical spaceship reactor. The application shows that, keeping the constraints satisfied, MACNOS is able to seek for the shielding design that minimizes the total weight by changing the thickness and the material of the shield. Therefore, it is expected that MACNOS is potentially useful in the search for the optimal design configuration in the conceptual design phase, where the selection of the shielding material and the estimate of the thickness are necessary.
    Annals of Nuclear Energy 02/2010; 37(2):120-129. · 1.02 Impact Factor
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    ABSTRACT: This research evaluates the effect of physiological responses during electrical acupuncture (EA) stimulation on specific acupuncture points (APs: PC5 and PC6). A variety of special responses in the human body were determined by electroencephalogram (EEG), heart rate (HR) in an electrocardiogram (ECG), and skin impedance test for 2 groups, sham group as a control and a group under acupuncture stimulation. The total stimulation time in this study was set for 5 min since the effect of EA on all recorded parameters became stable within this period. According to the experiments, during EA stimulation of PC5 and PC6, the power spectrum of EEG showed that the number of low frequency waves was increased in all lobes. Heart rate variability measures of 10 subjects stimulation trials at PC6 and PC5 were compared to 10 subjects who received no stimulation treatment. In both the AP and the sham groups, the mean R-R interval increased significantly during EA stimulation. A comparison between the AP and non-AP group in terms of skin resistance measurement experiments revealed no difference in skin resistance. The results of this study verified that EA stimulation of APs (PC5, PC6) causes EEG changes, and ECG heart rate changes. However, from human skin impedance measurements, the beneficial effects were not sustained. These results may be helpful in the understanding of the mechanism underlying the effect of electrical acupuncture on PC6 and PC5.
    The American Journal of Chinese Medicine 02/2009; 37(3):505-17. · 2.63 Impact Factor
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    ABSTRACT: In this study, we have fabricated non-contact temperature sensor using an infrared optical fiber for measuring temperature distributions during radiofrequency ablation. We have measured an infrared radiation, which is transferred by a silver halide optical fiber from the multi-points on the water around inserted electrode, using a thermopile sensor and the output voltages of a thermopile sensor are compared with those of the thermocouple recorder. Also, the relationship between the temperatures and the output voltages of a thermopile sensor at the measuring points is determined to obtain the temperature distribution. The measurable temperature range of a fiber-optic non-contact temperature sensor is from 37 to 80 °C. Keywordsfiber-optic sensor-infrared radiation-noncontact temperature sensor-radiofrequency ablation-silver halide optical fiber
    Optical Review 01/2009; 16(3):387-391. · 0.55 Impact Factor
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    ABSTRACT: A scintillating fiber-optic dosimeter has many advantages such as real-time readout, high-resolution measurement, water-equivalence and no corrections for temperature, pressure and humidity. Organic scintillator which has water or tissue equivalent characteristics is very important to measure absorbed dose, dose rate and dose distributions exactly without any corrections and due to its small size, the sensitive volume enables accurate dose measurements in regions of high dose gradients with high spatial resolution. In this study, a scintillating fiber-optic dosimeter with an organic scintillator is fabricated to measure high-energy photon beam from a clinical linear accelerator. And we have measured linear responses of a fiber-optic dosimeter according to dose rates and monitor units of a clinical linear accelerator. Also, a percent depth dose curve for 6MV photon beam with different field sizes are obtained. Keywordsorganic scintillator-fiber-optic dosimeter-photon beam-radiotherapy
    Optical Review 01/2009; 16(3):383-386. · 0.55 Impact Factor
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    ABSTRACT: In this study, a one-dimensional fiber-optic scintillating detector was developed for electron-beam therapy dosimetry. Each fiber-optic detector contains an organic scintillator as a sensitive volume and it is embedded and arrayed in a plastic phantom to measure one-dimensional high-energy electron-beam profiles of clinical linear accelerators. Plastic optical fibers guide the scintillating light which each detector probe generates to a photodiode array. The one-dimensional electron-beam profiles in the plastic phantom were measured in two different field sizes and for two electron-beam energies. Also, isodose and two-dimensional dose distributions in the plastic phantom were obtained using the one-dimensional scintillating detector array with two different electron beam energies.
    IEEE Transactions on Nuclear Science 11/2008; · 1.46 Impact Factor
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    ABSTRACT: In this study, we fabricated a fiber-optic radiation sensor with an organic scintillator to measure the high-energy photon beam from a clinical linear accelerator, and a two-dimensional fiber-optic sensor array to measure high-resolution and real-time dose distributions for small field radiotherapy dosimetry. The scintillating lights generated from each organic sensor probe embedded and arrayed in a water phantom are guided by 10 m plastic optical fibers to the light-measuring device. Two-dimensional photon beam distributions in a water phantom were measured for photon beams with different energies and field sizes. Also, percent depth dose curves for 6 and 15 MV photon beams were obtained.
    IEEE Transactions on Nuclear Science 11/2008; · 1.46 Impact Factor
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    ABSTRACT: In this study, we have developed a non-contact temperature sensor using a silver halide optical fiber for medical endoscopic usage. We have measured an infrared radiation which is transferred by a silver halide optical fiber from a heat source using a thermal optical power-meter and a thermopile sensor. To increase the amount of infrared radiation through the silver halide optical fiber and to the infrared sensors, optical devices such as an infrared collimator and a focusing lens are used. The relationships between the temperatures of a heat source and the measured output signals are determined. The measurable temperature range of a fiber-optic temperature sensor is from 30 to 60degC. It is expected that a non-contact temperature sensor using an infrared optical fiber can be developed for medical and industrial usages based on the results of this study.
    01/2008;
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    ABSTRACT: Usually, two kinds of light signals such as scintillating and Cerenkov light are generated in a fiber-optic dosimeter when a high energy electron beam is irradiated. The objectives of this study are to measure, characterize and remove a Cerenkov light generated in a scintillating fiber-optic dosimeter. The intensity of Cerenkov light is measured and characterized as a function of incident angle of electron beam from a linear accelerator, as a function of electron beam energy, and as a function of electron beam size using a photodiode amp system and a charge-coupled device. Also, a subtraction method using a background optical fiber without a scintillator is investigated to remove a Cerenkov light.
    01/2008;

Publication Stats

121 Citations
27.01 Total Impact Points

Institutions

  • 2013
    • Gyeongju University
      Gyeongju, North Gyeongsang, South Korea
  • 2007–2013
    • Dongguk University
      • College of Science and Technology
      Sŏul, Seoul, South Korea
  • 2010
    • Konkuk University
      • Department of Biological Engineering
      Seoul, Seoul, South Korea
  • 2001–2006
    • Seoul National University
      • Department of Nuclear Engineering
      Sŏul, Seoul, South Korea
  • 2004–2005
    • Korea Institute of Nuclear Safety
      Sŏul, Seoul, South Korea
  • 1999
    • Korea Hydro and Nuclear Power - Central Research Institute
      Sŏul, Seoul, South Korea