• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.666-671
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• 2014

Using positive temperature coefficient (PTC) heater as supplementary heating for diesel engine vehicles with low heat source is a good method to enhance the heating performance during cold start. In this study, the PTC elements were made by using screen printing process for forming ohmic contact layer, and prototype of PTC heater was designed and made for a diesel engine vehicle. In process of designing the PTC heater, the thermal flow analysis of PTC element modules was conducted for verifying the effect of the shapes of contact surface between each of the components (cooling fin, insulator, ceramic element). We also investigated the performance characteristic (heating capacity, energy efficiency, pressure drop) of the PTC heater through the experiments. Therefore, the experimental results indicated that prototype of PTC heater had satisfactory performance. This study will be basis for improving the manufacturing process and increasing the performance of the PTC element and heater.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.499-505
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• 2007

The major effective of this study is to investigate the fatigue effects of rail pad on High Speed Railway with concrete slab track system. It analyzed the mechanical behaviors of HSR concrete slab track with applying rail pad stiffness based on fatigue effect (hardening and increasing stiffness) on the 3-dimensional FE analysis and laboratory test for static & dynamic characteristics. As a result, the hardening of rail pad due to fatigue loading condition are negative effect for the static & dynamic response of concrete stab track which is before act on fatigue effect. The analytical and experimental study are carried out to investigate rail pad on fatigue effected increase vertical acceleration and stress and decrease suitable deflection on slab track. And rail pad based on fatigue effect induced dynamic maximum stresses, the increase of damage of slab track is predicted by adopting fatigue effected rail pad. after due consideration. The servicing HSR concrete slab track with resilient track system has need of the reasonable determination after due consideration fatigue effect of rail pad stiffness which could be reducing the effect of static and dynamic behavior that degradation phenomenon of structure by an unusual response characteristic and a drop durability.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.06a
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• pp.3-3
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• 2001

Recently TiN, TiAlN, CrN hardcoatings have adapted many industrial application such as die, mold and cutting tools because of good wear resistant and thermal stability. However, in terms of high speed process, general hard coatings have been limited by oxidation and thermal hardness drop. Especially in the case of PCB drill, high speed cutting and without lubricant process condition have not adapted these coatings until now. Therefore more recently, superhard nanocomposite coating which have superhard and good thermal stability have developed. In previous works, WC-TiAlN new nanocomposite film was investigated by cathodic arc ion plating system. Control of AI concentration, WC-TiAlN multi layer composite coating with controlled microstructure was carried out and provides additional enhancement of mechanical properties as well as oxidation resistance at elevated temperature. It is noted that microhardness ofWC-TiA1N multi layer composite coating increased up to 50 Gpa and got thermal stability about $900^{\circ}C$. In this study WC-TiAlN nanocomposite coating was deposited on PCB drill for enhancement of life time. The parameter was A1 concentration and plasma cleaning time for edge sharpness maintaining. The characteristic of WC-TiAlN film formation and wear behaviors are discussed with data from AlES, XRD, EDS and SEM analysis. Through field test, enhancement of life time for PCB drill was measured.

• International Journal of Computer Science & Network Security
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• v.23 no.1
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• pp.153-163
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• 2023

This study is situated in the context of intelligent transport systems, where in-vehicle devices assist drivers to avoid accidents and therefore improve road safety. The vehicles present in a given area form an ad' hoc network of vehicles called vehicular ad' hoc network. In this type of network, the nodes are mobile vehicles and the messages exchanged are messages to warn about obstacles that may hinder the correct driving. Node mobilities make it impossible for inter-node communication to be end-to-end. Recognizing this characteristic has led to delay-tolerant vehicular networks. Embedded devices have small buffers (memory) to hold messages that a node needs to transmit when no other node is within its visibility range for transmission. The performance of a vehicular delay-tolerant network is closely tied to the successful management of the nodes' transit buffer. In this paper, we propose a message transit buffer management model for nodes in vehicular delay tolerant networks. This model consists in setting up, on the one hand, a policy of dropping messages from the buffer when the buffer is full and must receive a new message. This drop policy is based on the concept of intermediate node to destination, queues and priority class of service. It is also based on the properties of the message (size, weight, number of hops, number of replications, remaining time-to-live, etc.). On the other hand, the model defines the policy for selecting the message to be transmitted. The proposed model was evaluated with the ONE opportunistic network simulator based on a 4000m x 4000m area of downtown Bouaké in Côte d'Ivoire. The map data were imported using the Open Street Map tool. The results obtained show that our model improves the delivery ratio of security alert messages, reduces their delivery delay and network overload compared to the existing model. This improvement in communication within a network of vehicles can contribute to the improvement of road safety.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.2_2
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• pp.289-297
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• 2022

Deterioration in durability of structures due to the steel corrosion is difficult to determine whether or not corrosion is initiated and how much propagated, and moreover, repair and maintenance are not easy to deal with. Therefore, preventive treatments can be the best option to avoid the deterioration. Various methods for preventing corrosion of steel, such as electrochemical treatments, anti-corrosion agents and steel surface coatings, are being developed, but economic and environmental aspects make it difficult to apply them to in-situ field. Thus, the purpose of this study was to improve corrosion resistance by using CA-based clinker that are relatively simple and expected to be economically profitable Existing CA-based clinkers had problems such as flash setting and low strength development during the initial hydration process, but in order to solve this problem, CA clinker with low initial reactivity were used as binder in this study. The cement paste used in the experiments was replaced with CA₂ clinker for 0%, 10%, 20%, and 30% in OPC. And the mixture used in the chloride binding test for the extraction of water-soluble chloride was intermixed with Cl- 0.5%, 1%, 2%, and 3% by weight of binder content. To evaluate characteristic of hydration heat evolution, calorimetry analysis was performed and simultaneously chloride binding capacity and acid neutralization capacity were carried out. The identification of hydration products with curing ages was verified by X-ray diffraction analysis. The free chloride extraction test showed that the chlorine ion holding ability improved in order OC 10 > OC 30 > OC 20 > OC 0 and the pH drop resistance test showed that the resistance capability in pH 12 was OC 0 > OA 10 > OA 20 > OA 30. The XRD analyses showed that AFm phase, which can affect the ability to hold chlorine ions, tended to increase when CA₂ was mixed, and that in pH12 the content of calcium hydroxide (Ca(OH)₂), which indicates pH-low resistance, decreased as CA₂ was mixed

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.11
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• pp.1423-1433
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• 2018

Recently, a permanent magnet synchronous motor of middle and small-capacity has high torque, high precision control and acceleration / deceleration characteristics. But existing control has several problems that include unpredictable disturbances and parameter changes in the high accuracy and rigidity control industry or nonlinear dynamic characteristics not considered in the driving part. In addition, in the drive method for the control of low-vibration and high-precision, the process of connecting the permanent magnet synchronous motor and the load may cause the response characteristic of the system to become very unstable, to cause vibration, and to overload the system. In order to solve these problems, various studies such as adaptive control, optimal control, robust control and artificial neural network have been actively conducted. In this paper, an incremental encoder of the permanent magnet synchronous motor is used to detect the position of the rotor. And the position of the detected rotor is used for low vibration and high precision position control. As the controller, we propose augmented state feedback control with a speed observer and first order deadbeat disturbance observer. The augmented state feedback controller performs control that the position of the rotor reaches the reference position quickly and precisely. The addition of the speed observer to this augmented state feedback controller compensates for the drop in speed response characteristics by using the previously calculated speed value for the control. The first order deadbeat disturbance observer performs control to reduce the vibration of the motor by compensating for the vibrating component or disturbance that the mechanism has. Since the deadbeat disturbance observer has a characteristic of being vulnerable to noise, it is supplemented by moving average filter method to reduce the influence of the noise. Thus, the new controller with the first order deadbeat disturbance observer can perform more robustness and precise the position control for the influence of large inertial load and natural frequency. The simulation stability and efficiency has been obtained through C language and Matlab Simulink. In addition, the experiment of actual 2.5[kW] permanent magnet synchronous motor was verified.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.31-40
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• 2012

u-GIS DSMSs have been researched to deal with various sensor data from GeoSensors in ubiquitous environment. Also, they has been more important for high availability. The data from GeoSensors have some characteristics that increase explosively. This characteristic could lead memory overflow and data loss. To solve the problem, various load shedding methods have been researched. Traditional methods drop the overloaded tuples according to a particular criteria in a single server. Tuple deletion sensitive queries such as aggregation is hard to satisfy accuracy. In this paper a dual processing load shedding method is suggested to improve the accuracy of aggregation in clustering environment. In this method two nodes use replicated stream data for high availability. They process a stream in two nodes by using a characteristic they share stream data. Stream data are synchronized between them with a window as a unit. Then, processed results are merged. We gain improved query accuracy without data loss.

• Journal of Mushroom
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• v.12 no.1
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• pp.41-51
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• 2014

Cauliflower mushroom widely known high concent of ${\beta}$-glucan for farm cultivation invigoration verified characteristics of mycelia growth, genetic diversity, resistance to Trichoderma by replacement culture with Trichoderma and growth characteristics of new variety crossbleeding strain. The result of replacement culture with Trichoderma for verification resistance about Trichoderma, 6951 (T. viride) strain did not show special change after formation of confrontation line and 6952 (T. spp.) strain was showed more formation of spore after formation of confrontation line. But 6426 (T. harzianum) strain found to encroach part of growth area of cauliflower mushroom mycelia. Among 10 kinds cauliflower mushroom strain, JF02-06 strain collected by Gurye, found did not spore of Trichoderma and thought to be resistant to Trichoderma. The result of crossbleeding after selected that mother strain good growth and formation of fruit body, verified good mycelia growth at JF02-47, 49 and 50 strain in Korean pine of wood-chip media. The result of gene sequence about ITS1, 5.8S and ITS4 for analysis of genetic diversity at crossbleeding strain, found high significance to other cauliflower mushroom in registered Genebank. The result of growth characteristic of spore and mycelia of cauliflower mushroom by observation microscope, size of spore showed water drop shape to major axis $6{\mu}m$ and minor axis $5{\mu}m$ and clamp showed 3 types in mycelia. The wide of mycelia was $3{\mu}m$. The characteristic of mycelia of cauliflower mushroom found to grow mycelia in clamp at approximately 50%. The growth speed of mycelia was $0.507{\mu}m/min$ and 2nd mycelia grown similar speed to mother mycelia at parallel with mother mycelia after growth speed at $0.082{\mu}m/min$. The formation of clamp made small clamp for 5 hours after shown transfer of electrolyte in mycelia inside. The septum formation started after 3 hours and then finally completed after 2 hours. In this study, strain of cauliflower mushroom verified resistance of Trichoderma, genetic diversity and characteristic of mycelia growth. Therefore, basic knowledge of cauliflower mushroom will improve and further contribute to development of mushroom industry.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.26-32
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• 2010

Purpose: It is to find the way to minimize occupationally exposed dose for workers in vivo tests in each working stage within the range of the working environment which does not ruin the examination and the performance efficiency. Materials and Methods: The process of the nuclear tests in vivo using a radioactive isotope consists of radioisotope distribution, a radioisotope injection ($^{99m}Tc$, $^{18}F$-FDG), and scanning and guiding patients. Using a measuring instrument of RadEye-G10 gamma survey meter (Thermo SCIENTIFIC), the exposure doses in each working stage are measured and evaluated. Before the radioisotope injection the patients are explained about the examination and educated about matters that require attention. It is to reduce the meeting time with the patients. In addition, workers are also educated about the outside exposure and have to put on the protected devices. When the radioisotope is injected to the patients the exposure doses are measured due to whether they are in the protected devices or not. It is also measured due to whether there are the explanation about the examination and the education about matters that require attention or not. The total exposure dose is visualized into the graph in using Microsoft office excel 2007. The difference of this doses are analyzed by wilcoxon signed ranks test in using SPSS (statistical package for the social science) program 12.0. In this case of p<0.01, this study is reliable in the statistics. Results: It was reliable in the statistics that the exposure dose of injecting $^{99m}Tc$-DPD 20 mCi in wearing the protected devices showed 88% smaller than the dose of injecting it without the protected devices. However, it was not reliable in the statistics that the exposure dose of injecting $^{18}F$-FDG 10 mCi with wearing protected devices had 26% decrease than without them. Training before injecting $^{99m}Tc$-DPD 20 mCi to patient made the exposure dose drop to 63% comparing with training after the injection. The dose of training before injecting $^{18}F$-FDG 10 mCi had 52% less then the training after the injection. Both of them were reliable in the statistics. Conclusion: In the examination of using the radioisotope $^{99m}Tc$, wearing the protected devices are more effective to reduce the exposure dose than without wearing them. In the case of using $^{18}F$-FDG, reducing meeting time with patients is more effective to drop the exposure dose. Therefore if we try to protect workers from radioactivity according to each radioisotope characteristic it could be more effective and active radiation shield from radioactivity.

• Korean journal of applied entomology
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• v.48 no.3
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• pp.301-310
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• 2009

For the comparing of mortality of the resistance and susceptible population of Myzus persicae, etofenprox was treated in the recommended concentration of 200ppm. Mortalities of resistance population were 16.7 and 36.7%, and susceptible population were 86.7 and 86.7% after 24 and 48 hours treatment, respectively. For the detect of cross resistance to other pyrethroids, 6 pyrethroids were examined. Mortalities of susceptible and resistance populations were 90 and 31% to deltamethrin, 92 and 23% to lambda cyhalothrin, 81 and 14% to cypermethrin, 70 and 20% to $\alpha$-cypermethrin, 29 and 28% to fenpropathrin, 84 and 29% to fenvalerate, respectively. It was showed that resistance populations were generally resistive to other pyrethroids. On the other hands, for recognized ecological characteristic of M. persicae susceptible and resistance populations life table was tested on the pepper leaves in the petri dish and on the plant in the pot. This results were showed that intrinsic rate of increase ($r_m$), net reproduction number ($R_0$) and generation time in day ($T_c$) were significantly different between two population in both tested. However, life span and reproduction period were slightly different between them. Otherwise, feeding behaviors were tested using EPG technique with non- and treated etofenprox. First potential drop time of susceptible and resistance population was 73.5 and 257.9 sec with non-treated and 93.3 and 1076.2 sec after treated, respectively. Electrical probing signals were 8.2 and 48.8 times with susceptible and resistance individuals after treated etofenprox, respectively. It was supposed that the resistance is more probings than susceptible population. After treated, total feeding time have more 6,728.9 sec on resistance than 965.5 sec on susceptible population. So, total non penetration time of susceptible population was 3,000 sec longer than resistance population.