• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.154-155
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• 2007

This paper describes frequency response of two-mass system for gyroscope applications. The two-mass system of the proposed device is adapted to the sensing part of the gyroscope in this research. Two-mass system has two resonant peaks and wide flat region between two resonant peaks. The resonant frequency of driving part is in this flat region. Therefore, frequency tuning is not necessary for mode matching. In the proposed device, resonant frequency is designed as 7183 Hz in driving part. Mass ratio of two masses in sensing part is 0.1 and device size is 6 mm $\times$ 6 mm. The device is fabricated by SiOG process. The fabricated spring width is increased from $4{\mu}m$ to $4.5{\sim}4.7{\mu}m$, and the measured resonant frequency is 8392 Hz in driving mode. We operated the sensing part using parallel plate of proof mass to verify the sensing part. It is confirmed the device has a wide fiat region in frequency response curve and the resonant frequency of the driving part is in the wide flat region of sensing mode.

• Journal of Welding and Joining
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• v.25 no.6
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• pp.71-77
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• 2007

Until now, many researches on laser-arc hybrid welding processes have been conducted mainly for high power CW laser and high direct current arc to weld the thick steel plates for shipbuilding. Recently, however the usage of thin steel plates, which tend to be deformed easily by thermal energy, is been increasing because of demand of light structure such as car body in the automobile industry. Accordingly, heat sources having relatively low heat input such as pulsed laser, dip-transfer DC GMA and pulsed GMA seem to be applied more increasingly and the study about those heat sources is needed more intensively. Any heat source mentioned above can not stand alone without weld defects at a relatively high welding speed for increasing the welding productivity. This is main reason to apply the hybrid welding process which uses pulsed laser and low-heat-input GMA heat sources simultaneously to weld the thin steel plate. In this study, parameters of pulsed laser and dip-transfer DC GMA welding are studied firstly through preliminary experiments, and then analyzed in the viewpoint of their physical phenomena. Before conducting the hybrid welding, a pulse control technique is developed based on the parallel port communication and Visual C++ 6.0. Owing to development of this technique, interactions of laser and arc pulses can be controlled consistently. Using the pulse control technique, the hybrid welding is conducted and then its interactive welding phenomenon is analyzed.

• ALGAE
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• v.28 no.4
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• pp.331-341
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• 2013

Rhinomonas reticulata var. atrorosea G. Novarino is a photosynthetic marine flagellate that is known to have typical characteristics of cryptomonads. We examined the flagellar apparatus of R. reticulata var. atrorosea by transmission electron microscopy. The major components of the flagellar apparatus of R. reticulata var. atrorosea consisted of four types of microtubular roots (1r, 2r, 3r, and mr), a non-keeled rhizostyle (Rhs), mitochondrion-associated lamella (ML), two connections between basal bodies, a striated fibrous root (SR) and a striated fiber-associated microtubular root (SRm). Four types of microtubular roots originated near the ventral basal body and extended toward the left side of the basal bodies. The non-keeled Rhs originated at the Rhs-associated striated fiber, which was located between two basal bodies and extended into the middle of the cell. The ML was a plate-like fibrous structure associated with mitochondria and originating from a Rhs-associated fiber. It split into two parts and extended toward the dorsal-posterior of the cell to a mitochondrion. The SR and SRm extended parallel to the anterior lobe of the cell. The overall configuration of the flagellar apparatus in R. reticulata var. atrorosea was similar to the previously reported descriptions of those of Cryptomonas paramecium, C. pyrenoidifera, C. ovata, Hanusia phi, Guillardia theta, and Proteomonas sulcata. However, the flagellar apparatus system of R. reticulata var. atrorosea was more complex than those of other cryptomonad species due to the presence of an additional microtubular root and other distinctive features, such as a rhizostyle-associated striated fiber and large ML.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1964-1969
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• 2021

We developed a Dual-PPACs detector for fast neutron measurements that consists of two sets of PPAC: conventional PPAC and fission PPAC. A²³⁸U(U₃O₈) coating is placed in the fission PPAC's anode, which is used as the neutrons conversion layer. An experiment was performed to measure neutron time-of-flight (TOF) in which ²⁵²Cf spontaneous fission source was used. An excellent time resolution of 164ps has been observed at 6 mbar in isobutene gas. With the excellent time resolution of Dual-PPACs detector, exact neutron energy can be extracted from the timing measurement. The experimental detection efficiency was 1.9 × 10^-7, consistent with the efficiency of 2.5 × 10^-7 given by a Geant4 simulation. Ultimately, the results show that the Dual-PPACs detector is a suitable candidate for measuring fast neutrons in the future CiADS system.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.2
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• pp.77-85
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• 2023

In this study, the mechanical properties of the Al-Mg-X (X=Cr, Si) alloy, which clearly showed the influence of the specimen and grain size, were investigated by changing the specimen size extensively. In addition, the effect on the specimen size, grain size and aging condition on the mechanical properties of the grain refining alloy according to the addition of Cr was clarified, and the relationship between these factors was studied. As the specimen size decreased, the yield stress decreased and the fracture elongation increased. This change was evident in alloys with coarse grain sizes. Through FEM analysis, it was confirmed that the plastic deformation was localized in the parallel part of specimen S2. Therefore, when designing a tensile specimen of plate material, the W/L balance should be considered along with the radius of curvature of the shoulder. In the case of under-aged materials of alloys with coarse grain size, the fracture pattern changed from intergranular fracture to transgranular fracture as W/d decreased, and δ increased. This is due to the decrease in the binding force between grains due to the decrease in W. In the specimen with W/d > 40 or more, intergranular fracture occurred, and local elongation did not appear. Under-aged materials of alloys with fine grain size always had transgranular fracture over a wide range of W/d = 70~400. As W/d decreased, δ increased, but the change was not as large as that of alloys with coarse grain sizes. Compared to the under-aged material, the peak-aged material did not show significant dependence on the specimen size of σ_0.2 and δ.

• Journal of Platform Technology
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• v.12 no.1
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• pp.119-127
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• 2024

This paper utilized electromagnetic field energy as an external stimulus to enhance the germination rate of acacia(Robinia pseudoacacia) seeds. Electromagnetic field energy comprises three types: static magnetic field(SMF) energy, static electric field(SEF) energy, and microwave(MW) energy. When SMF energy was applied to seeds through a dry method for 90 minutes, the germination rate increased by more than 10% compared to the control group. Similarly, SEF energy applied through a dry method for 90 minutes resulted in an improvement of over 20% in the germination rate. Furthermore, when MW energy at 2.45 GHz was applied to the seeds through a wet method for 3 minutes, the germination rate increased by over 25%. Experimental results showed that seeds treated with MW energy exhibited the highest germination rate and the greatest sprout growth. Consequently, this paper confirms that treating seeds with MW energy through a wet method yields the most superior germination rate and seedling growth.

• Progress in Medical Physics
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• v.17 no.1
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• pp.1-5
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• 2006

A parallel plate detector containing PTFE films in FEP film for relative dosimetry was designed to measure the response of detectors to S and 10 MV X-rays from a medical linear accelerator through different thicknesses of lead. The dielectric materials were 100 m thick. The set-up conditions for measurements with this detector were as follows: SSD=100 cm the test detector was at a depth of 5 cm and the reference chamber was at a depth of 10 cm from the phantom surface for 6 and 10 MV X-rays. Lead blocks were designed to cover the irradiated field. They were added to the tray to increase thickness sequentially. We found that the detector response decreased exponentially with the thickness of lead added. The linear attenuation coefficients of the test detector and reference chamber were 0.1414 and 0.541, respectively, for 6 MV X-rays and 0.1358 and 0.5279 for 10 MV X-rays. The test detector response was greater than that of the reference chamber. The response function was calculated from the measured values of the test detector and reference chamber using optimization. These optimized constants for the detector response function were independent of theenergy. As a result of optimizing the response function between detectors, the use of a relative dosimeter was validated, because the response of the test detector was 1% for 6 MV X-rays and 4% for 10 MV X-rays.

• Radiation Oncology Journal
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• v.12 no.2
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• pp.225-232
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• 1994

Purpose : This study was to obtain the basic dosimetric data using the 10 MV X-ray for the total body irradiation. Materials and Methods : A linear accelerator photon beam is planned to be used as a radiation source for total body irradiation (TBI) in Chonnam University Hospital. The planned distance from the target to the midplane of a patient is 360cm and the maximum geometric field size is 144cm x 144cm. Polystyrene phantom sized $30{\times}30{\times}30.2cm^3$ and consisted of several sheets with various thickness, and a parallel plate ionization chamber were used to measure surface dose and percent depth dose (PDD) at 345cm SSD, and dose profiles. To evaluate whether a beam modifier is necessary for TBI, dosimetry in build up region was made first with no modifier and next with an 1cm thick acryl plate 20cm far from the polystyrene phantom surface. For a fixed sourec-chamber distance, output factors were measured for various depth. Results : As any beam modifier was not on the way of radiation of 10MV X-ray, the $d_{max}$ and surface dose was 1.8cm and $61\%$, respectively, for 345cm SSD. When an 1cm thick acryl plate was put 20cm far from polystyrene phantom for the SSD, the $d_{max}$ and surface dose were 0.8cm and $94\%$, respectively. With acryl as a beam spoiler, the PDD at 10cm depth was $78.4\%$ and exit dose was a little higher than expected dose at interface of exit surface. For two-opposing fields for a 30cm phantom thick phantom, the surface dose and maximum dose relative to mid-depth dose in our experiments were $102.5\%$ and $106.3\%$, respectively. The off-axis distance of that point of $95\%$ of beam axis dose were 70cm on principal axis and 80cm on diagonal axis. Conclusion: 1. To increase surface dose for TBI by 10MV X-ray at 360cm SAD, 1cm thick acrylic spoiler was sufficient when distance from phantom surface to spoiler was 20cm. 2. At 345cm SSD, 10MV X-ray beam of full field produced a satisfiable dose uniformity for TBI within $7\%$ in the phantom of 30cm thickness by two-opposing irradiation technique. 3. The uniform dose distribution region was 67cm on principal axis of the beam and 80cm on diagonal axis from beam axis. 4. The output factors at mid-point of various thickness revealed linear relation with depth, and it could be applicable to practical TBI.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.1
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• pp.55-59
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• 2000

A specific and sensitive sandwich enzyme-immunoassay (EIA) using Avidin-Biotin complex was developed for the measurement of GTH II levels in pituitary content and pituitary cell culture medium of the rainbow trout-(Oncorhpchus mykiss). Biotin-salmon GTH II rabbit IgG (sefondary antibody) wai purified by a protein A sepharose affinity chromatography column and that was biotinylated by using Biotin-N-hydroxysuccinimide ofter (BNHS). Non-biotin salmon GTH II rabbit IgG (first antibody) was obtained only through a protein A sepharose affinity chromatography column. The assay was performed by the so-called 'sandwich' method using a microtiter plate, A dose-response curve was obtained between $0.12 to 125 ng/ml$ of salmon GTH II. The displacement curves for pituitary extraction and pituitary cell culture medium of testosterone-treated rainbow trout were Parallel to the standard curie. The intra-assay and inter-assay coefficients of variation (CV) were $8.2{\%} (N=5) and 12.5{\%} (N=6)$, respectively, This assay system was used to measure the amount of GTH II that accumulated in the culture medium of dispersed pituitary cells in testosterone-treated immature rainbow trout, The accumulation was increased with the amount or salmon gonadotropin-releasing hormone. GTH II values determined by the present method were well correlated with those determined by radioimmunoassay. As a result, this assay system was found to be suitable for the measurement of GTH II for pituitary extraction and pituitary culture medium in many salmonid fishes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5452-5457
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• 2012

It is saving material cost and construction cost by replacing conventional building materials, and It has advantages for aesthetic value. In the Europe, the United States, Japan and other country research about BIPV is actively being carried out and marketability is also being infinity expanding. Arch type PV systems efficiency characteristics is different depending on PV array's directly connection, parallel connection and arches angle, but is a lack of analysis on this nowadays. When the arch type PV system design up, they consider about aesthetic value and they didn't consider about generation efficiency. In this paper, we try to improve the efficiency through optimization of arch type PV system and estimation of the efficiency parameters of the arch type PV system, such as latitude, longitude, temperature, insolation, arch angle and each kind loss from system organization. For improving Arched PV system efficiency, proposed multiple control inverter system, and using simulation tool of Arched PV system "Solar pro", flat-plate type and many arch type PV system configuration the driving characteristics were compared and analyzed.