• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.157-164
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• 2003

Introduction of wave model, considered the effect of tide, wind and wave induced currents at the coastal waters of complex bathymetry, is a very important factor for most coastal engineering design and disaster protection problems. As the steady state spectral wave model could simulate depth induced wave shoaling and refraction, current induced refraction effect, steepness induced wave breaking, diffraction, wind wave growth, and wave-wave interaction that redistribute energy, this would support and compensate the gap in the real field of design where other wave models could not deal and cause wrong estimation. In this study, for that sense, we applied the spectral wave model t the large coastal waters near Gaduck Island where the Busan new port construction project is going on, for better understanding and analysis of wave transformation process. We also compared the simulation results with the calculated from the existing model. From such a trial of this study, we hope that broader and sager use of the spectral model in the area of port design and disaster prevention system come through in near future.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.6
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• pp.497-500
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• 2017

This paper proposes a circularly polarized microstrip antenna using an I-shape ground slot perturbation and a perpendicular feeding network. The proposed antenna consists of the symmetrical and perpendicular feeding and the microstrip square radiator loaded with the I-shape ground slot perturbation. The left-handed circular polarization(LHCP) formed by a 90-degree phase difference can be radiated by the perpendicular feeding network and the ground slot perturbation. An implemented antenna is designed for the use in the satellite communication system operated in S-band of 2.2 GHz, and is to be the 91 MHz of -10 dB bandwidth. The measured results of the antenna gain, far-field radiation pattern, and axial ratio agree well with the simulation results.

• Korean journal of applied entomology
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• v.22 no.3 s.56
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• pp.228-231
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• 1983

In order to eradicate harmful insect by use of sterile male techniques, it is necessary to disperse about 10 times as many male insect as in wild condition. However, it is so difficult to discriminate male insect in pupal stage that usually the population are likely to be contaminated by female insect when that are released in field. The present study was conducted to establish a useful method capable of differenciating the male pupae of Stomawys calcitsans by means of measuring the pupal weight and length. The results were summarized as follows; 1. Male pupa was lighter and shorter than female and high correlation existed between length and width of pupa. 2. There was significant relationship between the length of pupa and width of adult 3. When the pupal sex of stable ay was identified by median of mean length and mean weight of the pupae, the Ratio of female to male was 1 : 1. 4 and 1 : 2. 2, respectively. Therefore, median of pupal weight seemed to be applicable for obtaining more number of male pupae.

• Korean Journal of Environmental Agriculture
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• v.14 no.1
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• pp.1-6
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• 1995

This experiment was carried out to clarify the evapotranspiration and water use efficiency in rice plant canopy. Two rice cultivars, Daechungbyo(japonica type) and Samgangbyo(Tongil) were planted on the field of Suwon Weather Forecast Station in 1989. Evapotranspiration, dry matter production and leaf area of rice plant were measured to investigate the water use efficiency. There was significant correlation between cumulative evapotranspiration and dry matter production of aboveground. The parameter of linear regression was 4.13. The ratio of cumulative top dry matter production per cumulative evapotranspiration was increased until $5.5{\sim}5.9$ leaf area index. The de Wit's "m" value revealed maximum record at heading-flowering stage. At the harvest, the values were ranged from 175.5 to 191.7. The parameter of cumulative solar radiation to dry matter production was $1.011{\sim}1.248$. The evapotranspiration ratio(g.water/g.DW) of Samgangbyo(278) was higher than that of Daechungbyo (299.9). The efficiency of evapotranspiration(g.DW/g. water) was 1.58 in Daechungbyo and 1.98 in Samgangbyo.

• Journal of radiological science and technology
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• v.37 no.4
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• pp.341-348
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• 2014

Wedge filter could use to increase the dose distribution at the hot dose regions. We evaluated dose discrepancy at surface and build region in the infield and outfield that Metal Wedge (MW) and Enhance Dynamic Wedge (EDW) were interact with photon. In this paper, we used Gafchromic EBT3 film that had excellent spatial resolution, composed the water equivalent materials and changed the optical density without development. The set up conditions of linear accelerator were fixed 6 MV photon, 100 cm SSD, $10{\times}10cm^2$ field size and were irradiated 400 cGy at Dmax. The dose distribution and absorbed dose were evaluated when we compared the open field with $15^{\circ}$, $30^{\circ}$, $45^{\circ}$ metal wedge and enhanced dynamic wedge. A $15^{\circ}$ metal wedge could increase the surface and build up region dose than using a $15^{\circ}$ enhanced dynamic wedge. A $30^{\circ}$ metal wedge could decrease the surface and build up region dose than using a $30^{\circ}$ enhanced dynamic wedge. A $45^{\circ}$ metal wedge could decrease by large deviation the surface and build up region dose than using a $15^{\circ}$ enhanced dynamic wedge. The dose of penumbra region at outfield were increased on the thick side but were decreased on the thin side. It could be decrease the surface dose and build up region dose, if the metal wedge filters were properly used to make a good dose distribution and not closed the distance of surface.

• Journal of Electrical Engineering and information Science
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• v.3 no.2
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• pp.239-244
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• 1998

Piezoelectric pressure sensors and pyroelectric infrared detectors based on ZnO thin film have been integrated with GaAs metal-semiconductor field effect transistor (MESFET) amplifiers. Surface micromachining techniques have been applied in a GaAs MESFET process to form both microsensors and electronic circuits. The on-chip integration of microsensors such as pressure sensors and infrared detectors with GaAs integrated circuits is attractive because of the higher operating temperature up to 200 oC for GaAs devices compared to 125 oC for silicon devices and radiation hardness for infrared imaging applications. The microsensors incorporate a 1${\mu}$m-thick sputtered ZnO capacitor supported by a 2${\mu}$m-thick aluminum membrane formed on a semi-insulating GaAs substrate. The piezoelectric pressure sensor of an area 80${\times}$80 ${\mu}$m2 designed for use as a miniature microphone exhibits 2.99${\mu}$V/${\mu}$ bar sensitivity at 400Hz. The voltage responsivity and the detectivity of a single infrared detector of an area 80${\times}$80 $\mu\textrm{m}$2 is 700 V/W and 6${\times}$108cm$.$ Hz/W at 10Hz respectively, and the time constant of the sensor with the amplifying circuit is 53 ms. Circuits using 4${\mu}$m-gate GaAs MESFETs are fabricated in planar, direct ion-implanted process. The measured transconductance of a 4${\mu}$m-gate GaAs MESFET is 25.6 mS/mm and 12.4 mS/mm at 27 oC and 200oC, respectively. A differential amplifier whose voltage gain in 33.7 dB using 4${\mu}$m gate GaAs MESFETs is fabricated for high selectivity to the physical variable being sensed.

• Progress in Medical Physics
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• v.15 no.2
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• pp.63-69
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• 2004

HDR brachytherapy administers a large dose of radiation in a short time compare with LDR, and its optimization for treatment is related to several complex factors, such as physical, radiation and optimization algorithms, so there is a need for these to be verified for accurate dose delivery. In our approach, a previous study concerning the phantom for dose verification has been modified, and a new pelvic phantom fabricated for the purpose of localization, including a structure enabling the use of a CT or MRI system. In addition, a comparison study was performed to verify an orthogonal method that is commonly used for brachytherapy localization by comparing target coordinates from a CT system. Since the developed phantom was designed to simulate the clinical setups of cervix cancer, it included an air-filled bladder and a rectum structure shaped sphere and cylinder An N-shaped localizer was used to obtain precision coordinates from both CT and films. Moreover, the IDL 5.5 software program for Windows was used to perform coordinates analysis based on an orthogonal algorithm. The film results showed differences within 1.0 mm of the selected target points compare with the CT coordinates. For these results, a Plato planning system (Nucletron, Netherlands) could be independently verified using this phantom and software. Furthermore, the new phantom and software will be efficient and powerful qualify assurance (QA) tools in the field of brachytherapy QA.

• Journal of Space Technology and Applications
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• v.1 no.2
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• pp.256-267
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• 2021

In this paper, the New Space characteristics and response of micro & small satellite, and space industrialization strategy using domestic technologies are described. Recently, micro & small satellites are developed worldwide, including Starlink, having the characteristics of low-cost, light-weight and satellite constellation. Therefore, it is necessary to prepare for the constellation operation by considering the use of Commercial Off-The-Shelf (COTS) parts, satellite weight, shape and mass production. In particular, it is necessary to develop Multi Input Multi Output (MIMO) technology in consideration of the frequency interference during constellation operation, and to prepare and make efforts to secure frequencies in the government. Among the commercial-grade memories of Samsung Electronics and SK Hynix, the space-grade memory field using radiation tolerant memory and the high reliable packaging and space environment test technology has potential as a space industrialization strategy.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2613-2620
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• 2023

Excellent thermal neutron absorption performance of boron expands the potential use of boron rich slag to prepare epoxy resin matrix nuclear shielding composites. However, shielding attenuation behaviors and mechanism of the composites against gamma rays are unclear. Based on the radiation protection theory, Phy-X/PSD, XCOM, and ⁶⁰Co gamma ray source were integrated to obtain the shielding parameters of boron rich slag/epoxy resin composites at 0.015-15 MeV, which include mass attenuation coefficient (µ_t), linear attenuation coefficient (µ), half value thickness layer (HVL), electron density (N_eff), effective atomic number (Z_eff), exposure buildup factor (EBF) and exposure absorption buildup factor (EABF).µ_t, µ, HVL, N_eff, Z_eff, EBF and EABF are 0.02-7 cm²/g, 0.04-17 cm^-1, 0.045-20 cm, 5-14, 3 × 10²³-8 × 10²³ electron/g, 0-2000, and 0-3500. Shielding performance is BS4, BS3, BS3, BS1 in descending order, but worse than ordinary concrete. µ and HVL of BS1-BS4 for ⁶⁰Co gamma ray is 0.095-0.110 cm^-1 and 6.3-7.2 cm. Shielding mechanism is main interactions for attenuation gamma ray by BS1-BS4 are elements with higher content or higher atomic number via Photoelectric Absorption at low energy range, and elements with higher content via Compton Scattering and Pair Production in Nuclear Field at middle and higher energy range.

• Journal of Radiation Protection and Research
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• v.39 no.4
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• pp.199-205
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• 2014

In the field of neutron detections, $^3He$ gas, the so-called "the gold standard," is the most widely used material for neutron detections because of its high efficiency in neutron capturing. However, from variable causes since early 2009, $^3He$ is being depleted, which has maintained an upward pressure on its cost. For this reason, the demands for $^3He$ replacements are rising sharply. Research into neutron converting materials, which has not been used well due to a neutron detection efficiency lower than the efficiency of $^3He$, although it can be chosen for use in a neutron detector, has been highlighted again. $^{10}B$, which is one of the $^3He$ replacements, such as $BF_3$, $^6Li$, $^{10}B$, $Gd_2O_2S$, is being researched by various detector development groups owing to a number of advantages such as easy gamma-ray discrimination, non-toxicity, low cost, etc. One of the possible techniques for the detection is an indirect neutron detection method measuring secondary radiation generated by interactions between neutrons and $^{10}B$. Because of the mean free path of alpha particle from interactions that are very short in a solid material, the thickness of $^{10}B$ should be thin. Therefore, to increase the neutron detection efficiency, it is important to make a $^{10}B$ thin film. In this study, we fabricated a $^{10}B$ thin film that is about 60 um in thickness for neutron detection using well-known technology for the manufacturing of a thin electrode for use in lithium ion batteries. In addition, by performing simple physical tests on the conductivity, dispersion, adhesion, and flexibility, we confirmed that the physical characteristics of the fabricated $^{10}B$ thin film are good. Using the fabricated $^{10}B$ thin film, we made a proportional counter for neutron monitoring and measured the neutron pulse height spectrum at a neutron facility at KAERI. Furthermore, we calculated using the Monte Carlo simulation the change of neutron detection efficiency according to the number of thin film layers. In conclusion, we suggest a fabrication method of a $^{10}B$ thin film using the technology used in making a thin electrode of lithium ion batteries and made the $^{10}B$ thin film for neutron detection using suggested method.