• Journal of IKEEE
• /
• v.23 no.4
• /
• pp.1461-1464
• /
• 2019

In this paper, we propose the development of embedded board for integrated radiation exposure protection fireman's life-saving alarm capable of location tracking and radiation measurement. The proposed techniques consist of signal processing unit, communication unit, power unit, main control unit. Signal processing units apply shielding design, noise reduction technology and electromagnetic wave subtraction technology. The communication unit is designed to communicate using the wifi method. In the main control unit, power consumption is reduced to a minimum, and a high performance system is formed through small, high density and low heat generation. The proposed techniques are equipment operated by exposure to poor conditions, such as disaster and fire sites, so they are designed and manufactured for external appearance considering waterproof and thermal endurance. The proposed techniques were tested by an authorized testing agency to determine the effectiveness of embedded board. The waterproof grade has achieved the IP67 rating, which can maintain stable performance even when flooded with water at the disaster site due to the nature of the fireman's equipment. The operating temperature was measured in the range of -10℃ to 50℃ to cope with a wide range of environmental changes at the disaster site. The battery life was measured to be available 144 hours after a single charge to cope with emergency disasters such as a collapse accident. The maximum communication distance, including the PCB, was measured to operate at 54.2 meters, a range wider than the existing 50 meters, at a straight line with the command-and-control vehicle in the event of a disaster. Therefore, the effectiveness of embedded board for embedded board for integrated radiation exposure protection fireman's life-saving alarm has been demonstrated.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.3
• /
• pp.166-177
• /
• 2006

The cache size tends to grow in the embedded processor as technology scales to smaller transistors and lower supply voltages. However, larger cache size demands more energy. Accordingly, the ratio of the cache energy consumption to the total processor energy is growing. Many cache energy schemes have been proposed for reducing the cache energy consumption. However, these previous schemes are concerned with one side for reducing the cache energy consumption, dynamic cache energy only, or static cache energy only. In this paper, we propose a hybrid scheme for reducing dynamic and static cache energy, simultaneously. for this hybrid scheme, we adopt two existing techniques to reduce static cache energy consumption, drowsy cache technique, and to reduce dynamic cache energy consumption, way-prediction technique. Additionally, we propose a early wake-up technique based on program counter to reduce penalty caused by applying drowsy cache technique. We focus on level 1 data cache. The hybrid scheme can reduce static and dynamic cache energy consumption simultaneously, furthermore our early wake-up scheme can reduce extra program execution cycles caused by applying the hybrid scheme.

• Korean Chemical Engineering Research
• /
• v.51 no.2
• /
• pp.267-271
• /
• 2013

Test bed studies with highly efficient amine $CO_2$ solvent (KoSol-4) developed by KEPCO research institute were performed. For the first time in Korea, evaluation of post-combustion $CO_2$ capture technology to capture 2 ton $CO_2$/day from a slipstream of the flue gas from a coal-fired power station was performed. Also the analysis of solvent regeneration energy was conducted to suggest the reliable performance data of the KoSol-4 solvent. For this purpose, we have tested 5 campaigns changing the operating conditions of the solvent flow rate and the stripper pressure. The overall results of these campaigns showed that the $CO_2$ removal rate met the technical guideline ($CO_2$ removal rate: 90%) suggested by IEA-GHG and that the regeneration energy of the KoSol-4 showed about 3.0~3.2 GJ/$tCO_2$ which was, compared to that of the commercial solvent MEA (Monoethanolamine), about 25% reduction of regeneration energy. Based on these results, we could confirm the good performance of the KoSol-4 solvent and the $CO_2$ capture process developed by KEPCO research institute. And also it was expected that the cost of $CO_2$ avoided could be reduced drastically if the KoSol-4 is applied to the commercial scale $CO_2$ capture plant.

• Applied Chemistry for Engineering
• /
• v.27 no.4
• /
• pp.391-396
• /
• 2016

The absorption efficiency of amine $CO_2$ absorbent (KoSol-5) developed by KEPCO research institute was evaluated using a 0.1 MW test bed. The performance of post-combustion technology to capture two tons of $CO_2$ per day from a slipstream of the flue gas from a 500 MW coal-fired power station was first confirmed in Korea. Also the analysis of the absorbent regeneration energy was conducted to suggest the reliable data for the KoSol-5 absorbent performance. And we tested energy reduction effects by improving the absorption tower inter-cooling system. Overall results showed that the $CO_2$ removal rate met the technical guideline ($CO_2$ removal rate : 90%) suggested by IEA-GHG. Also the regeneration energy of the KoSol-5 showed about $3.05GJ/tonCO_2$ which was about 25% reduction in the regeneration energy compared to that of using the commercial absorbent MEA (Monoethanolamine). Based on current experiments, the KoSol-5 absorbent showed high efficiency for $CO_2$ capture. It is expected that the application of KoSol-5 to commercial scale $CO_2$ capture plants could dramatically reduce $CO_2$ capture costs.

• Journal of the Korea Concrete Institute
• /
• v.19 no.1
• /
• pp.121-130
• /
• 2007

To investigate the enhancement in strength and deformation capacities of concrete confined by FRP composites, tests under axial loads were carried out on three groups of thirty six short columns in circular section with diverse GFRP confining reinforcement. The major test variables considered include fiber content or orientation, wrap or tube type by varying the end loading condition, and continuous or discontinuous confinement depending on the presence of vortical spices between its two halves. The circumferential FRP strains at failure for different types of confinements were also investigated with emphasis. Various analytical models capable of predicting the ultimate strength and strain of the confined concrete were examined by comparing to observed results. Tests results showed that FRP wraps or tubes provide the substantial increase in strength and deformation, while partial wraps comprising the vertical discontinuities fail in an explosive manner with less increase in strength, particularly in deformation. A bilinear stress-strain response was observed throughout all tests with some variations of strain hardening. The failure hoop strains measured on the FRP surface were less than those obtained from the tensile coupons in all tests with a high degree of variation. In overall, existing predictive equations overestimated ultimate strengths and strains observed in present tests, with a much larger scatter related to the latter. For more accuracy, two simple design- oriented equations correlated with present tests are proposed. The strength equation was derived using the Mohr-Coulomb failure criterion, whereas the strain equation was based on entirely fitting of test data including the unconfined concrete strength as one of governing factors.

• Journal of Aquaculture
• /
• v.13 no.3
• /
• pp.267-275
• /
• 2000

To evaluate the characteristics and efficiency of oxygen transfer rate of a polystyrene foam bead as media in a packed column aerator was tested. This media has more surface area and cheaper than other ordinary plastic media. The polystyrene foam media was a sphere-shaped bead with 2.5 mm in diameter and specific surface area was 1,350 $m^2$/$m^3$. Oxygen transfer rate and standard aeration efficiency were tested under different hydraulic loading rates, depths of the media and temperatures. Experiment 1 was performed using a small packed column aerator with 10 cm in diameter and 1 m in length. The aerator filled with 0, 4.5, 9.0 and 18.0 cm of the media was tested under hydraulic loading rates of 2.0, 4.0 and 5.6 $m^3$/$m^2$/min at temperatures of 20, 25 and 3$0^{\circ}C$, respectively. In this experiment, standard oxygen transfer rate (SOTR) increased with the hydraulic loading rate and depth of the media increased. The maximum SOTR was reached at 5.6 $m^3$/$m^2$/min of hydraulic loading rate with 9 cm in depth of the media. However, standard aeration efficiency (SAE) decreased with the hydraulic loading rate increased because electricity consumed by pump increased as hydraulic loading rate increased. The highest SAE was reached at hydraulic loading rate of 2.0 $m^3$/$m^2$/min with 9.0 cm in depth of the media. Therefore, the highest SOTR and SAE were achieved at 9.0 cm in depth of the media regardless of the hydraulic loading rate. The maximum SAE was about 1.8 kg $O_2$/kW-hr with the hydraulic loading .ate of $m^3$/$m^2$/min at temperature of 20 $^{\circ}C$.Experiment 2 was performed using a larger aerator, 20 cm in diameter with 2 m in height. The aerator filled with 0, 9, 18, 27 and 36 cm of the media was operated under hydraulic loading rate of 2.0, 4.0 and 5.6 $m^3$/$m^2$/min at temperature of 27 $^{\circ}C$. The SAE reached to the highest efficiency (1.9 kg $O_2$/kW-hr) at 2.0 $m^3$/$m^2$/min of hydraulic loading rate and 36 cm in depth of the media. According to the above results, the polystyrene foam bead as a media in a packed column aerator was effective to increase oxygen transfer rate.

• Progress in Medical Physics
• /
• v.23 no.3
• /
• pp.154-161
• /
• 2012

Digital Radiography (DR) has rapidly developed in megavoltage X-ray imaging (MVI). Thus, a very simple and general quality assurance (QA) method is required. The purpose of this study was to evaluate the modulation transfer function (MTF), the noise power spectrum (NPS) and the detective quantum efficiency (DQE) for MVI using general QA method and computed radiography (CR) device. We used tungsten edge block with $19{\times}10{\times}1cm^3$ thickness and 6MV energy. For detector, CR-IP (image plate), CR-IP-lead, the CR-IP-back (lanex TM fast back screen), CR-IP-front (lanex TM fast front screen) were used and pre-sampling MTF was calculated. The MTF of CR-IP-front showed the highest value with 1.10 lp/mm although the CR-IP showed the only 0.70 lp/mm. The best NPS was observed in CR-IP front screen. According to the increase in spatial frequency, our results showed that DQE was approximately 1.0 cycles/mm. The present study demonstrates that the QA method with our home-made edge block can be used to evaluate MTF, NPS and DQE for MVI.

• Korean Chemical Engineering Research
• /
• v.55 no.3
• /
• pp.419-425
• /
• 2017

In this study, the performance characteristics of the K-based sorbents (KEP-CO2P2, KEPCO RI, Korea) has been studied in relation with the heat exchanger structure and shape in a mixing zone of the carbonator in the bench-scale dry $CO_2$ capture process. Two types of heat exchangers (different structure and shape) were used in the carbonator as CASE 1 and CASE 2, in which the experiment has been continuously performed under the same operating conditions. During the continuous operation, working temperature of carbonator was 75 to $80^{\circ}C$, that of regenerator was 190 to $200^{\circ}C$, and $CO_2$ inlet concentration of the feed gas was 12 to 14 vol%. Especially, to compare the dynamic sorption capacity of sorbents, the differential pressure of the mixing zone in the carbonator was maintained around 400 to 500 mm $H_2O$. Also, solid samples from the carbonator and the regenerator were collected and weight variation of those samples was evaluated by TGA. The $CO_2$ removal efficiency and the dynamic sorption capacity were 64.3% and 2.40 wt%, respectively for CASE 1 while they were 81.0% and 4.66 wt%, respectively for CASE 2. Also, the dynamic sorption capacity of the sorbent in CASE 1 and CASE 2 was 2.51 wt% and 4.89 wt%, respectively, based on the weight loss of the TGA measurement results. Therefore, It was concluded that there could be a difference in the performance characteristics of the same sorbents according to the structure and type of heat exchanger inserted in the carbonator under the same operating conditions.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.24 no.2
• /
• pp.169-181
• /
• 2008

The aim of this study was to compare the retention and stability of implant overdenture according to the shape and the number of magnetic attachment. The experimental groups were designed for the number of implants(1, 2, 4) and shape of magnetic attachments(flat, cushion, dome type) resulting in 9 subgroups. 45 attachments were tested attached to $Br{\aa}nemark$ system implants which were planted on a mandibular model. Each attachment was composed of the magnet assembly embedded in a overdenture sample and the abutment keeper screwed into the implants. Dislodging tensile forces were applied to the overdenture samples using an Instron(cross-head speed 50.80mm/min) in 3 directions simulating function: vertical, oblique, and anterior-posterior. The loading was repeated 10 times in each direction for 45 samples. The values of maximum dislodging force of each subgroup were processed statistically using SPSS V. 12.0 at the 0.05 level of significance. The results of this study were as follows: 1. Flat type magnetic overdenture was the most retentive when subjected to vertically directed forces and dome type was the lest retentive when subjected to obliquely directed forces(p<0.05). 2. In case of planting one implant, flat type had a higher vertically retentive force than anterior-posteriorly retentive force. In case of planting two implants, flat type and dome type had a higher vertically retentive force and in case of planting four implants, flat type and cushion type had a higher vertically retentive force than anterior-posteriorly retentive force(p<0.05). 3. The incremental number of dental implant, without regards to the three types of magnetic attachment shapes, showed higher retention of overdenture(p<0.05). From the results, if a patient need much more retention of implant overdenture, flat type magnetic overdenture would be a good treatment. In case of the bruxism where excessive lateral forces are already present, dome type could be expected to produce better results. In case of planting one implant, flat type is more stable than the other shape of magnet and in case of two implant, flat type and dome type are more stable and in case of four implants, flat type and cushion type are more stable. Planting more than two implants and using flat type magnetic attachment would provide better retention and stability of implant overdenture

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.12
• /
• pp.6-13
• /
• 2009

For X-band phased array systems, a power amplifier, a 6-bit phase shifter, a 6-bit digital attenuator, and a SPDT transmit/receive (T/R) switch are fabricated and measured. All circuits are demonstrated by using CMOS 0.18 um technology. The power amplifier has 2-stage differential and cascade structures. It provides 1-dB gain-compressed output power ($P_{1dB}$) of 20 dBm and power-added-efficiency (PAE) of 19 % at 8-11 GHz frequencies. The 6-bit phase shifter utilizes embedded switched filter structure which consists of nMOS transistors as a switch and meandered microstrip lines for desired inductances. It has $360^{\circ}$ phase-control range and $5.6^{\circ}$ phase resolution. At 8-11 GHz frequencies, it has RMS phase and amplitude errors are below $5^{\circ}$ and 0.8 dB, and insertion loss of $-15.7\;{\pm}\;1,1\;dB$. The 6-bit digital attenuator is comprised of embedded switched Pi-and T-type attenuators resistive networks and nMOS switches and employes compensation circuits for low insertion phase variation. It has max. attenuation of 31.5 dB and 0.5 dB amplitude resolution. Its RMS amplitude and phase errors are below 0.4 dB and $2^{\circ}$ at 8-11 GHz frequencies, and insertion loss is $-10.5\;{\pm}\;0.8\;dB$. The SPDT T/R switch has series and shunt transistor pairs on transmit and receive path, and only one inductance to reduce chip area. It shows insertion loss of -1.5 dB, return loss below -15 dB, and isolation about -30 dB. The fabricated chip areas are $1.28\;mm^2$, $1.9mm^2$, $0.34\;mm^2$, $0.02mm^2$, respectively.