• Fire Science and Engineering
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• v.34 no.3
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• pp.67-75
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• 2020

In this study, the risk of heat generation due to normal and overload currents that vary with the abnormal loosening angle of wire-connecting bolts were identified. The risks were analyzed based on the thermal characteristics to minimize the carbonization accidents of terminal blocks inside distribution panels typically used in industrial sites. We applied a method for measuring the heating temperature and temperature variations in the terminal blocks in real-time by installing a resistance temperature detector sensor board in the terminal block. The experimental results showed that the terminal block model with a low-rated current exhibited a higher heating temperature, thus, confirming the need to select the terminal block capacity based on load currents. Additionally, the higher the rated current of the terminal block with a high-rated current and the higher the degree of loosening, the faster the carbonization point. Such heating temperature monitoring enabled real-time thermal temperature measurement and a step-by-step risk level setting through thermal analysis. The results of the measurement and analysis of carbonization risks can provide a theoretical basis for further research regarding the risk of fire due to carbonization. Furthermore, the deterioration measurement method using the temperature sensor board developed in this study is widely applicable to prevent fires caused by poor electrical contact as well as risk-level management.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.566-572
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• 2020

In a wireless power transmitter, the characteristics and effects of wireless power transmission between two induction coils are investigated, and a power converter circuit and a battery charger/discharger circuit using wireless power transmission technology are proposed. The advantage of wireless power transmitters and wireless chargers is that, instead of the existing plug-in-mounted wired charger (OBC; on-board charger), the user can wirelessly charge the battery without connecting the power source when charging power to the battery. There is. In addition, the advantage of wireless charging can bring about an energy efficiency improvement effect by using the secondary side rectifier circuit and the receiving coil, but the large-capacity long-distance wireless charging method has a limitation on the transmission distance, so many studies are currently being conducted. The purpose of the study is to study the transmitter circuit and receiver circuit of a wireless power transmission device using a primary coil, a secondary coil, and a half bridge series resonance converter, which can transmit power of a non-contact type power transmitter. As a result, a new topology was applied to improve the power transmission distance of the wireless charging system, and through an experiment according to each distance, the maximum efficiency (95.8%) was confirmed at an output of 3 kW at an 8 cm transmission distance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.167-174
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• 2020

The purpose of this study was to investigate the kinematic comparison between successful and failed trials of Lopez vault techniques in male gymnastics. The subject, an Olympic gold medalist, was YHS (age: 27 years, height: 1.6 m, and mass: 53 kg) and fourteen high speed motion capturing cameras were used for data collection. The 26 reflective sensors were attached on major anatomical positions and 15 segment-body model was used to calculate the kinematic variables. According to results, the contact duration of the spring-board for successful trial(ST) was longer and that of failed trial(FT) and the range of motion of knee joint for ST was greater than that of FT. The movement times during pre-flight between ST and FT were same, but the movement time of horse contact period for ST was shorter than that of FT. The ST showed a longer movement time during post-flight and the longer horizontal distance than those of FT. Conclusively, YHS needs to approach the horse with a higher position of the body and higher incidence angle, as well as make faster twist angular velocity in an attempt to achieve ST.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.191-197
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• 2005

A new method, ToxTemp (TOXcity test based on TEMPerature control) using Ceridaphnia dubia was applied to evaluate the toxicity of insecticide materials and compared with the standard 48 hr acute bioassay. BPMC, diazinon and fenitrothion may cause the inhibition to the biological process in sewage treatment plant and need to detect toxicity within short contact time. The ToxTemp method showed sensitive detection with more shorter contact of 1-1.5 hr time than that of the standard 48 hr acute bioassay. To evaluate toxicity of real wastewater/sewage, the inhibition rate of nitrification and oxygen uptake rate (OUR) using activated sludge, the standard 48hr acute bioassay and ToxTemp method using C. dubia were compared, respectively. On the basis of the inhibition rate of nitrification, the OUR test showed the less sensitive results at the relatively strong toxic sewage. On the other hands, the standard 48hr acute bioassay and ToxTemp method using C. dubia represented the toxicity of each wastewater/sewage with high sensitivity. Even the slightly low (about 1.5%) sensitivity, the ToxTemp method showed the high applicability to the real site of sewage treatment plant.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.29-37
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• 2014

Telemetry, satellite event and error information are used to check the satellite status in ground station. Different from telemetry which only informs the parameter value, event and error gives explicit information of a certain operation or status. Event also contains ground action information because every command execution is logged as event. Currently, those information is gathered and applied only for monitoring of the satellite. However, the load of the operation is getting grown because of the excessively increased information of the satellite with the number of satellite increasement. Also, the process of reporting problem to developer (or an expert) induce time delay for satellites fault management. In this paper, we propose a satellite operation assistant system which collects event sequence and stores in different group by its feature, and then recommends or executes an appropriate action for the identified abnormal state. This system is applicable to on board system for resolving LEO-satellite autonomous fault situation since is has limited contact time.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.319-319
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• 2013

Even though the fabrication methods of metal oxide based thin film capacitor have been well established such as RF sputtering, Sol-gel, metal organic chemical vapor deposition (MOCVD), ion beam assisted deposition (IBAD) and pulsed laser deposition (PLD), an applicable capacitor of printed circuit board (PCB) has not realized yet by these methods. Barium Strontium Titanate (BST) and other high-k ceramic oxides are important materials used in integrated passive devices, multi-chip modules (MCM), high-density interconnect, and chip-scale packaging. Thin film multi-layer technology is strongly demanded for having high capacitance (120 nF/$mm^2$). In this study, we suggest novel multi-layer thin film capacitor design and fabrication technology utilized by plasma assisted deposition and photolithography processes. Ba0.6Sr0.4TiO3 (BST) was used for the dielectric material since it has high dielectric constant and low dielectric loss. 5-layered BST and Pt thin films with multi-layer sandwich structures were formed on Pt/Ti/$SiO_2$/Si substrate by RF-magnetron sputtering and DC-sputtering. Pt electrodes and BST layers were patterned to reveal internal electrodes by photolithography. SiO2 passivation layer was deposited by plasma-enhanced chemical vapor deposition (PE-CVD). The passivation layer plays an important role to prevent short connection between the electrodes. It was patterned to create holes for the connection between internal electrodes and external electrodes by reactive-ion etching (RIE). External contact pads were formed by Pt electrodes. The microstructure and dielectric characteristics of the capacitors were investigated by scanning electron microscopy (SEM) and impedance analyzer, respectively. In conclusion, the 0402 sized thin film multi-layer capacitors have been demonstrated, which have capacitance of 10 nF. They are expected to be used for decoupling purpose and have been fabricated with high yield.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.5
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• pp.367-375
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• 2012

Midfacial reconstruction following resection of extensive malignant oral cavity tumors constitutes a challenging problems for reconstructive surgeons. Rectus abdominis muscle free flap (RAMFF) can be considered as the optimal reconstructive option in this case, because this flap has some advantages including consistent deep inferior epigastric artery anatomy, easy to dissect with well defined skin boundaries, acceptable donor site morbidity and the ability to perform simultaneous flap harvest with oral cancer ablation surgery. The rectus abdominis muscle forms an important part of the anterior abdominal wall and flexes the vertebral column, which is a long strap-like muscle divided transversely by three tendinous intersections, fibrous bands which are adherent to the anterior rectus sheath, which is thickly enclosed by the rectus sheath, except for the posterior part below the arcuate line that is usually located midway between the umbilicus and symphysis pubis. Below the arcuate line, this muscle lies in direct contact with the transversalis fascia and parietal peritoneum. For the better understanding of RAMFF as a routine reconstructive procedure in oral and maxillofacial surgery, the constant anatomical findings muse be learned and memorized by the young doctors in the course of the special curriculum periods for the Korean national board of oral and maxillofacial surgery. This review article will discuss the anatomical basis of RAMFF with Korean language.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.191-199
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• 2008

In this paper, we present a performance analysis and design and implementation results of a 2.4 GHz bio-radar system that can detect human heartbeat and respiration signals. In order to design a 2.4 GHz bio-radar system qualitatively, we investigate the electromagnetic properties of human tissues and calculate the target SNR of demodulation output with respect to distance. The target SNR is defined by the 90 % success ratio for detecting heartbeat signal. With this target SNR value, the performance and link budget of the bio-radar system is simulated using MATLAB. Using this link budget results, the direct conversion receiver is designed and Implemented in 4 layer printed circuit board(PCB). With output power of 0 dBm and 5 Hz bandwidth, 80 % success ratio of 50 cm is measured. Measurement results show a good agreement with simulation results.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.189-194
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• 2015

In this study, the heat radiation performance of COB LED according to the structure of thermoelectric device were compared. Thermoelectric device of the sheet copper structure and ceramic structure were used for bonding with the heating part of the COB LED. The temperature distribution in the bonding part of the thermoelectric device of COB LED was measured with a contact-type thermometer. The temperature variation of the thermoelectric device was measured by inputting the currents of 0.1A, 0.3A, 0.5A, and 0.7A. When 0.7A was applied, the temperature of the bonding part where there was a heat aggregation phenomenon of the COB LED was $59^{\circ}C$ for thermoelectric device of the sheet copper structure and $67^{\circ}C$ for the thermoelectric device of the ceramic structure. Therefore, the sheet copper thermoelectric device whose temperature was lower by $9^{\circ}C$ showed better heat radiation performance than those of the ceramic structure.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.4
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• pp.237-240
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• 2016

The improvement of irradiation intensity and irradiation uniformity is essential for large area and high power UVA light source application. In this study, large number of chips bonded by micro soldering technique were driven by low current, and current limiting diodes were configured to supply constant current to parallel circuits consisting of large number of series strings. The dimension of light source module circuit board was $350{\times}90mm^2$ and 16,650 numbers of 385 nm flip chip LEDs were used with a configuration of 90 parallel and 185 series strings. The space between LEDs in parallel and series strings were maintained at 1.9 mm and 1.0 mm distance, respectively. The size of the flip chip was $750{\times}750{\mu}m^2$ were used with contact pads of $260{\times}669{\mu}m^2$ size, and SAC (96.5 Sn/3.0 Ag/0.5 Cu) solder was used for flip chip bonding. The fabricated light source module with 7.5 m A supply current showed temperature rise of $66^{\circ}C$, whereas irradiation was measured to be $300mW/cm^2$. Inaddition, 0.23% variation of the constant current in each series string was demonstrated.