• Journal of the Korean Institute of Gas
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• v.7 no.4 s.21
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• pp.7-13
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• 2003

This study was carried out to optimize premixed burner and heat exchanger of the condensing gas boiler which can save energy by utilizing latent heat of combustion gas and reduce pollutant in exhaust gas. The heat exchanger of the gas boiler was composed of three parts, which were an upper, lower, and coil heat exchanger. The upper heat exchanger was placed outside of the premixed burner and a lower heat exchanger was located under the upper heat exchanger. And, coil heat exchanger rounded the outer surface of an upper and lower heat exchanger. The boiler designed by this research reaches turn-down ratio 4:1 in the domain of equivalence ratio 0.75${\~}$0.8 and thermal efficiency of $97\%$. Emission of NOx and CO concentration was under 20ppm and 140ppm at equivalence ratio 0.8. When diameter of the burner is replaced from 60mm to 50mm, emission of CO was reduced about 50ppm remarkably.

• Journal of the Korean Society of Food Science and Nutrition
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• v.7 no.1
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• pp.1-6
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• 1978

Muscle fillets of flounder, Limanda herzensteini, were sliced into small pieces and dehydrated by the methods of sun drying, hot air drying and vacuum freeze drying, and evaluated for the protein quality by the method of shortened pepsin pancreatin digest residue (SPPDR) index which is the modified method of shortened pepsin digest residue index. In the analysis of the muscle protein hydrolysates, glutamic acid, aspartic acid and lysine comprised about 39% of the total amino acids of the protein. The content of pure protein in flounder muscle was 18.8%. The result of nutritional evaluation of the dried muscle protein by the computation of the SPPDR index showed that the freeze dried flounder muscle protein was superior in the nutritional efficiency to the others, sun dried. The freeze dried flounder muscle protein marked 89 of the SPPDR index number which is quite similar to the muscle protein of terrestrial animal in nutritional quality.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.2
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• pp.231-239
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• 2008

USN and RFID, as new technologies for realization of ubiquitous computing, are closely related with each other technically. Nevertheless, these technologies are recognized as a separate research topic, and there are few researches on technical convergence of the two research areas. In this paper, we propose an efficient processing method of various kinds of sensor data which are used in USN environment to provide efficiency from the view point of not only convergence of USN and RFID technologies but also cost and extensibility. Especially, we propose a method of conversion of various sensor data into EPC data format which can be handled in a RFID middleware. Using the proposed method, RFID middleware systems based on international standard specification can handle not only RFID tag data but also general sensor data efficiently, and various types of ubiquitous application services can be implemented at low cost and in a short time.

• Journal of Convergence for Information Technology
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• v.7 no.2
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• pp.1-9
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• 2017

Recently, the DDoS attack using the amplifier method makes it difficult to distinguish the normal traffic from the normal server and it is difficult to detect even the attack detection. Since the SSDP protocol is a common protocol widely used in IoT devices, it is used as a DDoS amplification attack. In this paper, we analyze the reflector attack of SSDP which is one of the DDoS and suggest a technical proposal to detect and defend against the attack by managing the Mac address of each device. Also, we propose a control structure to protect the reflection attack of SSDP in Home IoT. The efficiency of the proposed system has been verified by performing an experimental attack on the virtual environment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.8 no.11
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• pp.17-25
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• 1985

In these days the industrial management are characterized by mass production. Mass production which is not possible without the rationalization in the process of production and the efficient scale of management needs development of technical administration. The object of this study is set up on the rationalization in the process of production. And this rationalization is a means to the aim of industrial management. So as to realize the rationalization in the process of production, we should think on plan of production and the line of balancing in processes of work. The line of balancing is considered as one of very valuable administration methods. The line of balancing that controls capacities and loads so that processes of work might balance in each other makes away with happenings of idleness and stagnation during the process of work As a natural consequence it follows (1) shortening in the period of Production, (2) more efficient, (3) removing the lots of tine and matter, (4) more efficient using in elements for production. Therefore, through the labour productivity and the efficiency of the process of production increased by these effects, the line of balancing was intended to curtail the basic cost. Though the previously said line of balancing could be applied to production, it should not be said that we can completely balance in each lines of work. In other words it is impossible that the line of balancing is completely executed in every lines of work. For that reason, we should arrange the level of balancing in lines. Nowaday, in our country, it is true that the line of balancing is hardly executed at manufacturing industries. Therefore if we execute and apply the line of balancing to manufacturing industries and the larger field as well , we could curtail the basic cost, through which we could reinforce not only the international competative power but increase the labour productivity. As a result, by these effects, we would rationalize the industrial management.

• Journal of the Korean Solar Energy Society
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• v.38 no.5
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• pp.49-62
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• 2018

This study aims to analyze the performance of solar thermal system with heat pump for domestic hot water and heat supply. There are four types of system. Systems are categorized based on the existence of a heat pump and the ways of controlling the working fluid circulating from the collector. Working fluid is controlled by either temperature level (categorized as system 1 and 2) or sequential flow (system 3 and 4). Heat balance of the system, the solar fraction, hot water and heating supply rates, and performance of heat pump are analyzed using TRNSYS and TESS component programs. Technical specifications of the main facilities are as follow; the area of the collector to $25m^2$, the volumes of the main tank and the buffer tank to $0.5m^3$ and $0.8m^3$, respectively. Heating capacity of the heat pump in the heating mode is set to 30,000 kJ / hr. Hot water supply set 65 liters per person each day, total heat transfer coefficient of the building to 1,500 kJ / kg.K. Indoor temperature is kept steadily around $22^{\circ}C$. The results are as follows; 6 months average solar fraction of system 1 turns out to be 39%, which is 6.7% higher than system 2 without the heat pump, indicating a 25% increase of solar fraction compared to that of system 2. In addition, the solar fraction of system 1 is 2% higher than that of system 3. Hot water and heating supply rate of system 1 are 93% and 35%, respectively. Considering the heat balance of the system, higher heat efficiency, and solar fraction, as whole, it can be concluded that system 1 is the most suitable system for hot water and heat supply.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.518-523
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• 2008

Using network communication, KTX OBCS is KTX's core device which inspects operation status of various electric equipments and supports driving command, train control, train's maintenance, train crew's driving. Since this device is manufactured as specialized system, being dependent on TGV manufacture specification and France's high speed train operation method, actual technic transfer is difficult. Therefore, there are many difficulties, since most of interface signals are connected with OBCS when function improvement, maintenance, various electric equipments(propulsion control device, auxiliary power supply device, door control device etc.) are replaced with localized ones, which are required in operational view after introduction of KTX. Ergo, this study would like to contribute to function improvement and maintenance's efficiency, furthermore to realize technical independence, escaping from dependency of developed foreign technology in high speed train and electric equipments, through KTX OBCS' function analysis and mutual interface information analysis with peripheral device(driver console, PID system, fault display device, various electric equipments).

• Journal of Korean Society on Water Environment
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• v.37 no.4
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• pp.263-274
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• 2021

This study presents the achievements and limitations of the voluntary-based Total Maximum Daily Load (TMDL) through statistical analysis of water quality monitoring data and performance assessments of TMDL plans implemented in the Gyeongan watershed. The results clearly showed that responsible local governments complied the allocated TMDL and the designated water quality goals were successfully achieved in the required period. This was possible because the Ministry of Environment provided innovative incentives, such as, relaxations of the existing tight land-use regulations and full-scale financial aids for constructing and operating public treatment facilities to draw local government voluntary participation. However, a couple of problems which decreased the effectiveness and efficiency of the voluntary TMDL were identified. The different TMDL implementation schedules between upstream (Yongin) and downstream (Gwangju) governments caused delay in water quality improvement and exaggerated TMDL allocation to the local development which made excessive investment in the treatment facilities. Although it is not directly related to the voluntary scheme, technical methods for establishing and assessing the water quality goals should be improved so that the effects of flow conditions on water quality are properly assessed. We expect that results of this case study contribute to developing a more effective voluntary-based scheme for the implementation of the so-called 'tributary TMDL' in the future.

• Tribology and Lubricants
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• v.37 no.2
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• pp.48-53
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• 2021

Wind energy is considered as the most competitive energy source in terms of power generation cost and efficiency. The power train of the pitch drive for a wind turbine uses a 3-stage complex planetary gear system in being developed locally. A gear train of the pitch drive consists of an electric or hydraulic motor and a planetary decelerator, which optimizes the pitch angle of the blade for wind generators in response to the change in wind speed. However, it is prone to many problems, such as excessive repair costs in case of failure. Complex planetary gears are very important parts of a pitch drive system because of strength problem. When gears are designed for the power train of a pitch drive, it is necessary to analyze the fatigue strength of gears. While calculating the specifications of the complex planetary gears along with the bending and compressive stresses of the gears, it is necessary to analyze the fatigue strength of gears to obtain an optimal design of the complex planetary gears in terms of cost and reliability. In this study, the specifications of planetary gears are calculated using a self-developed gear design program. The actual gear bending and compressive stresses of the planetary gear system were analyzed using the Lewes and Hertz equation. Additionally, the calculated specifications of the complex planetary gears were verified by evaluating the results from the Stress - No. of cycles curves of gears.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.9 no.4
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• pp.269-277
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• 2019

In this paper, the compatibility analysis on the track record operation center for the regional industry upbringing is presented. The renewable energy sources such as solar, wind and battery energy storage system have been widely spread in these days. Also the requirements on the efficiency, reliability and power demands of these distributed systems are increasing and they can be demands on the construction of the data track record center for renewable energy industries in order to promote the local industries. The analysis on the size of the de-centralized power system are performed based on the technical issues. The necessities, requirements and center goals to meet these missions are presented in the following session. The proposal of the 1 MW operation center construction and operations are presented in the result of the compatibility analysis. And the lists of the required equipments in the operation facilities are suggested to have proper operational capabilities. The results of this research can be applied in the fundamental data to promote the regional renewable industries.