• Journal of the Korean Wood Science and Technology
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• v.30 no.2
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• pp.172-179
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• 2002

In this study, two materials treated with a flame retardant were examined for their fire resistance. The first, MDF (medium density fiberboard) was overlaid by an oak sliced veneer, which was either treated by soaking in a 6wt.% solution of flame retardant chemicals (pentabromine-chlorinated paraffin) or non-treated and then was coated with either a flame retardant polyurethane coating or with a common polyurethane coating. The second material, Pinus koraiensis penal was either treated by a spray treatment using a flame retardant solution or non-treated and then was coated with either a flame retardant polyurethane coating or with a common polyurethane coating. Pentabromine-chorinated paraffin chemicals were added (6 part of urethane resin) as the flame retardant chemicals in the polyurethane coatings. In the fire resistance test, the th𝜃(℃·min) decreased with the flame retardant treatment or/and the flame retardant coatings, compared to the untreated sample Weight loss (%) decreased with the flame retardant treatment or/and the flame retardant coatings. The ignition time (sec.) increased and the residual flame time (sec.) decreased with the flame retardant treatment or/and flame retardant coatings. Therefore, the flame retardant treatment or/and flame retardant polyurethane coatings have excellent incombustibility.

• Journal of Platform Technology
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• v.11 no.2
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• pp.54-65
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• 2023

Due to the nature of electric vehicles, the batteries used for electric vehicles have a very large rated capacity. If an electric vehicle runs for a long time or an electric vehicle is abandoned due to a traffic accident, the electric vehicle battery becomes a waste battery. Even in vehicles that are being abandoned, the remaining capacity of waste batteries for electric vehicles is sufficient for other purposes. Waste batteries for automobiles are very expensive, so they need to be recycled and reused, but there was a problem that the standards for measuring the performance grade of waste batteries for recycling and reuse were insufficient. As a method for measuring the remaining capacity of waste battery, the most stable and reliable method is to measure the remaining capacity of battery using full charge and discharge. However, the inspection method by the full charging and discharging method varies depending on the capacity of the battery, but it takes more than a day to inspect, and many people are making great efforts to solve this problem. In this paper, an electric vehicle battery residual capacity analysis technique using voltage deviation between cells was studied and analyzed as a method to reduce inspection time for electric vehicle batteries. To this end, a full charging and discharging-based capacity measurement system was constructed, experimental data were collected using a nose or waste battery, and the correlation between the voltage deviation and the remaining capacity of the battery pack was analyzed to verify whether it can be used for battery inspection.

• Journal of the Korean Orthopaedic Association
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• v.52 no.1
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• pp.73-82
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• 2017

Purpose: To assess the chronological changes of disease-related kyphosis after chemotherapy alone. Materials and Methods: A total of 101 children aged 2 to 15 years with spinal tuberculosis, accompanied by various stages of disease processes were enrolled for analysis. By utilizing the images in them, the growth plate condition and chronological changes of kyphosis after chemotherapy were analyzed at two points in time; the first assessment was at post-chemotherapy one-year and second at the final discharge. Results: Complete disc destruction in the cervical, dorsal and lumbosacral spines was observed in 2 out of 40 children (5.0%), 8 out of 30 children (26.7%), and 6 out of 31 children (19.4%), respectively. In those cases, the residual kyphosis inevitably developed. In the remaining children, the discs were intact or partially damaged. Among the 101 children kyphotic deformity was maintained without change in 20 children (19.8%). Kyphosis decreased in 14 children (13.9%), while it increased in 67 children (66.3%) with non-recoverably damaged growth plate. Conclusion: Although it is tentatively possible to predict the deformity progress or non-progress and spontaneous correction at the time of the initial treatment, its predictive accuracy is low. Therefore, assessment of the chronological changes should be performed at the end of chemotherapy. In children with progressive curve change, assessment of deformity should be continued until maturity.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1A
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• pp.53-59
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• 2010

Recently, NDTs (Non-Destructive Techniques) using infrared camera are widely studied for detection of damage and void in RC (reinforced concrete) structures and they are also considered as an effective techniques for maintenance of infrastructures. The temperature on concrete surface depends on material and thermal properties such as specific heat, thermal conductivity, and thermal diffusion coefficient. Different porosity on cement mortar due to different mixture proportions can show different heat behavior in cooling stage. The porosity can affect physical and durability properties like strength and chloride diffusion coefficient as well. In this paper, active thermography which uses flash for heat induction is utilized and thermal characteristics on surface are evaluated. Samples of cement mortar with W/C (water to cement ratio) of 0.55 and 0.65 are prepared and physical properties like porosity, compressive strength, and chloride diffusion coefficient are evaluated. Then infrared thermography technique is carried out in a constant room condition (temperature $20{\sim}22^{\circ}C$ and relative humidity 55-60%). The mortar samples with higher porosity shows higher residual temperature at the cooling stage and also shows reduced critical time which shows constant temperature due to back wall effect. Furthermore, simple equation for critical time of back wall effect is suggested with porosity and experimental constants. These characteristics indicate the applicability of infrared thermography as an NDT for quality assessment of cement based composite like concrete. Physical properties and thermal behavior in cement mortar with different porosity are analyzed in discussed in this paper.

• 한국노년학
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• v.25 no.2
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• pp.171-193
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• 2005

Nowadays, the employment policies for older people is requested to become the new form in the change of information, globalization, and aging. It is discussed, simultaneously, about an age integrated society as the full time jobs' continuation and social jobs after the full time jobs. The discussion of jobs' continuation include from institutional system to age integrated society. Social jobs include from public labor to social wages. jobs' continuation passes over stabilization, regarding it as ideal society. social jobs are interpreted it as residual welfare, excluding the meaning of social solidarity. In fact, most of the debates is overwhelmed by the logic of economy. And so they pass over the quality of life of individuals. Therefore, this study critics the employment policies for older people in the present situation and states a direction improving the quality of life older people.

• The Transactions of the Korea Information Processing Society
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• v.13 no.9
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• pp.395-403
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• 2024

Recently, with the advancement of technology, the automotive industry has seen an increase in network connectivity. CAN (Controller Area Network) bus technology enables fast and efficient data communication between various electronic devices and systems within a vehicle, providing a platform that integrates and manages a wide range of functions, from core systems to auxiliary features. However, this increased connectivity raises concerns about network security, as external attackers could potentially gain access to the automotive network, taking control of the vehicle or stealing personal information. This paper analyzed abnormal messages occurring in CAN and confirmed that message occurrence periodicity, frequency, and data changes are important factors in the detection of abnormal messages. Through DBC decoding, the specific meanings of CAN messages were interpreted. Based on this, a model for classifying abnormalities was proposed using the GRU model to analyze the periodicity and trend of message occurrences by measuring the difference (residual) between the predicted and actual messages occurring within a certain period as an abnormality metric. Additionally, for multi-class classification of attack techniques on abnormal messages, a Random Forest model was introduced as a multi-classifier using message occurrence frequency, periodicity, and residuals, achieving improved performance. This model achieved a high accuracy of over 99% in detecting abnormal messages and demonstrated superior performance compared to other existing models.

• Geophysics and Geophysical Exploration
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• v.1 no.1
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• pp.25-30
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• 1998

Time-lapse crosswell seismic data, recorded before and after the cavity filling, showed that the filling increased the velocity at a known cavity zone in an old mine site in Inchon area. The seismic response depicted on the tomogram and in conjunction with the geologic data from drillings imply that the size of the cavity may be either small or filled by debris. In this study, I attempted to evaluate the filling effect by analyzing velocity measured from the time-lapse tomograms. The data acquired by a downhole airgun and 24-channel hydrophone system revealed that there exists measurable amounts of source statics. I presented a methodology to estimate the source statics. The procedure for this method is: 1) examine the source firing-time for each source, and remove the effect of irregular firing time, and 2) estimate the residual statics caused by inaccurate source positioning. This proposed multi-step inversion may reduce high frequency numerical noise and enhance the resolution at the zone of interest. The multi-step inversion with different starting models successfully shows the subtle velocity changes at the small cavity zone. The inversion procedure is: 1) conduct an inversion using regular sized cells, and generate an image of gross velocity structure by applying a 2-D median filter on the resulting tomogram, and 2) construct the starting velocity model by modifying the final velocity model from the first phase. The model was modified so that the zone of interest consists of small-sized grids. The final velocity model developed from the baseline survey was as a starting velocity model on the monitor inversion. Since we expected a velocity change only in the cavity zone, in the monitor inversion, we can significantly reduce the number of model parameters by fixing the model out-side the cavity zone equal to the baseline model.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.2
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• pp.105-118
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• 2000

Anchored measurements (12.5 hr) of suspended sediment concentration and other hydrodynamic parameters were carried out at two stations located at the entrance to Hampyung Bay in summer (August 1999). Tidal variations in water temperature and salinity were in the range of 26.0-27.9$^{\circ}C$ and 30.9-31.5, respectively, indicating exchange offshore and offshore water mass. Active tidal mixing processes at the entrance appear to destroy the otherwise vertical stratification in temperature and salinity in spite of strong solar heating in summer. On the contrary, suspended sediment concentrations show a marked stratification with increasing concentrations toward bottom layer. Clastic particles in suspended sediments consist mostly of very fine to fine silt (4-16 ${\mu}$m) with a poorly-sorted value of 14.7-25.9 ${\mu}$m. However, at slack time with less turbulent energy, flocs larger than 40 ${\mu}$m are formed by cohesion and inter-collision of particles, resulting in a higher settling velocity. Strong ebb-dominated and weak flood dominated tidal currents, in the southwestern and the northeastern part, respectively, result in a seaward residual flow of -10${\sim}$-20 cm $s^{-1}$ at station H1 and a bayward residual flow less than 5.0 cm $s^{-1}$ at station H2. However, mean concentration of suspended sediments at station H1 is higher at flood (95.0-144.1 mg $1^{-1}$) than in ebb (75.8-120.9 mg $1^{-1}$). On the contrary, at the station H2, the trend is reversed with higher concentration at the ebb (84.7-158.4 mg $1^{-1}$) than that at the flood (53.0-107.9 mg $1^{-1}$). As a result, seaward net suspended sediment fluxes ($f_{s}$) are calculated to be -1.7 ${\sim}$-$15.610^{3}$ kg $m^{-2}$ $s^{-1}$ through the whole water column. However, the stations H1 and H2 show definitely different values of the flux with higher ones in the former than in the latter. Alternatively, depth-integrated net suspended sediment loads ($\c{Q}_{s}$) for one tidal cycle are also toward the offshore with ranges of 0.37${\times}$$10^{3}$ kg $m^{-1}$ and 0.21${\times}$$10^{3}$ kg $m^{-1}$, at station H1 and H2, respectively. This seaward transport of suspended sediment in summer suggests that summer-time erosion in the Hampyung muddy tidal flats is a rather exceptional phenomenon compared to the general deposition reported for many other tidal flats on the west coast of Korea.

• Korean Journal of Clinical Laboratory Science
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• v.56 no.2
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• pp.147-155
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• 2024

Gallium-68-prostate-specific membrane antigen-11 (⁶⁸Ga-PSMA-11) is a positron emission tomography radiopharmaceutical that labels a Glu-urea-Lys-based ligand with ⁶⁸Ga, binding specifically to the PSMA. It is used widely for imaging recurrent prostate cancer and metastases. On the other hand, the preparation and quality control testing of ⁶⁸Ga-PSMA-11 in medical institutions takes over 60 minutes, limiting the daily capacity of ⁶⁸Ge/⁶⁸Ga generators. While the generator provides 1,110 MBq (30 mCi) nominally, its activity decreases over time, and the labeling yield declines irregularly. Consequently, additional preparations are needed, increasing radiation exposure for medical technicians, prolonging patient wait times, and necessitating production schedule adjustments. This study aimed to reduce the ⁶⁸Ga-PSMA-11 preparation time and optimize the automated synthesis system. By shortening the reaction time between ⁶⁸Ga and the PSMA-11 precursor and adjusting the number of purification steps, a faster and more cost-effective method was tested while maintaining quality. The final synthesis time was reduced from 30 to 20 minutes, meeting the standards for the HEPES content, residual solvent EtOH content, and radiochemical purity. This optimized procedure minimizes radiation exposure for medical technicians, reduces patient wait times, and maintains consistent production schedules, making it suitable for clinical application.

• Clinical and Experimental Pediatrics
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• v.52 no.4
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• pp.494-498
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• 2009

Purpose : Applicability of transcatheter closure of atrial septal defect (ASD) has been expanded by accumulation of clinical experiences and evolutions of the device. This study was performed to evaluate the safety and efficacy of transcatheter closure of ASD with Amplatzer septal occluder (ASO) in young children less than 3 years of age. Methods : From May 2003 to December 2005, 295 patients underwent transcatheter closure of ASD with ASO in the Severance Cardiovascular Hospital, Yonsei University Health System. Among them, 51 patients less than 3 years of age were enrolled in this study. We investigated procedural success rate, rate of residual shunt, frequency of complications, procedure/fluoroscopy time, and need of modified techniques for device implantation. Results : The median age was 2.1 years and median body weight was 12 kg. Implantation of device was successful in 50 patients (98%). Seven patients (15%) showed a small residual shunt 1 day after the procedure, but complete occlusion had been documented at 6 month follow-up in all patients (100%). The pulmonary to systemic flow ratio (Qp/Qs), peak systolic pulmonary artery pressure, and peak systolic right ventricular pressure had decreased significantly after closure of ASD. There were 2 complications including device embolization (1, 2%) and temporary groin hematoma (1, 2%). Conclusion : Transcatheter closure of ASD with ASO can be performed with satisfactory results and acceptable risk even in young children less than 3 years of age. We could suggest that even in very young children with ASD, there is no need to wait until they grow to a sufficient size for the transcatheter closure.