• Journal of the Korean Institute of Gas
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• v.7 no.4 s.21
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• pp.36-43
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• 2003

This paper provides the possibility of the district cooling system by using a LNG cold thermal energy. A liquefied natural gas provides a plenty of cooling source energy during a gasification of a liquefied natural gas. In recent, an ice thermal storage system is used for cooling a building, and a deep water source cooling system has been introduced as a district cooling system in which is used to cool the office towers and other large buildings in old and new downtown. LNG cooling energy refers to the reuse of a large body of naturally cold fluids as a heat sink for process and comfort space cooling as an alternative of conventional, refrigerant based cooling systems. Coincident with significant clean energy and operating cost savings, LNG cold energy cooling system offers radical reductions in air-borne pollutants and the release of environmentally harmful refrigerants in comparison to the conventional air-conditioning system. This study provides useful information on the basic design concepts, environmental considerations and performance related to the application of LNG cold thermal energy.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.5
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• pp.101-106
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• 2019

Carbon deposition on the turbine nozzle throat of a LOx/kerosene gas generator cycle(open cycle) engine causes performance reduction of the engine. Estimation methods for a turbine nozzle throat area are proposed. The discharge coefficient of the turbine nozzle was estimated with the turbine gas properties such as gas constant, specific heat ratio, and temperatures. The pressure ratio and temperature ratio of the turbine nozzle throat, was utilized to estimate the discharge coefficient also. Estimated discharge coefficient of turbine nozzle throat of KSLV-II 1st stage engine shows the carbon deposition effects on the turbine nozzle throat of a LOx/kerosene open cycle engine.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.6
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• pp.400-408
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• 2008

Multipurpose Dam, it produces electric energy by converting the potential energy into kinetic energy utilizing its head and quantity of the water. However, in this process, since during the time when the turbine connected to the hydraulic turbine generator revolves, there occurs a ceaseless loud noise, and due to this condition, it is true state that those people who work at inside of the power plant are damaging as hard as they are unable to concentrate on their work. Not only this, because the hydro-electric power generator room that locates at middle section between the hydraulic turbine room and the office is very large space volume, also since it was constructed chiefly by the reflecting material, it is functioning of amplify the noise when operating the generator, the soundproof measure against this condition is necessitated. On such viewpoint, I have presented the problem point of the relevant Hydraulic turbine dynamo and Hydraulic turbine dynamo room, and after improve such problem point, this study has ever investigated the satisfying degree about the noise-reduction at before and after of the improvement of soundproof measure, using the Auralizational technique that can experience virtual acoustic field. It is considering that such result could be utilized usefully as the fundamental material hereafter for the acoustic performance of the hydro-electric power generator room in dam and when its construction.

• Journal of architectural history
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• v.30 no.6
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• pp.45-58
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• 2021

This study aims to examine the changes in Pyongyang-bu during the late Joseon period and Pyeong-an Gamyeong through gazetteer, pictiroal maps and various literature. The results are as follows. To begin with, unlike other gamyeong, Pyongyang-bu had an exclusive government office facility from the beginning and had a different status because of the route for envoys from Ming. Therefore historical sites related to Gija were important. Second, the importance of Pyongyang city-wall increased even more through the Japanese Hideyoshi invasions in 1592 and the Manchu Invasion in 1636. However, since the post-war restoration was insufficient they focused on defense reducing the size of Pyongyang city wall. Third, as society stabilized, Pyongyangbu's finances were greatly secured. King Sukjong systematically reorganized Pyongyang city wall and facility of Pyongy-an gamyeong. The nothern wall in located high place, Gamyeong and storage in middle height and military force and guesthouse in the center of Pyongyang-bu. I-a and warehouse facilities in the far south were placed around the Daedonggwan. The urban structure that runs from Daedonggwan to Daedongmun was the same as other city. Another pertinent point is Pyeong-an gamyeong had more military facilities and rear garden and pavilion than before. In clunclusion, Pyeong-an gamyeong did not pass through three gates, but only through two gates. And it was characterized by more various space and having more pavilions than other gamyeong.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.12
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• pp.1691-1697
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• 2018

There has been a steady study of unmanned vehicle. So far, continuous research has brought news of the commercialization of unmanned vehicle. In addition, it has been applied in a variety of fields with another industry. A lot of research has been done, too, to apply inert driving indoors. Using LoRa network, which is a network dedicated to IoT, unmanned vehicle control system that is applied to LoRa network from a small space, or from an office hospital to a factory, is installed to increase efficiency when the performs special tasks. This paper presents solutions to a variety of problems by using LoRa network, which is dedicated to IoT, to recognize an unmanned vehicle as a single object, to communicate with surrounding objects, and to receive information necessary for driving indoors from a cloud server.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.247-249
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• 2016

Corporation, local government and government office provide useful information. Advertisement service is getting various manner. Typical example is electronic display, TV-advertisement and internet or mobile advertisement service. In this paper, I'm study about Taxi-advertisement service still. A similar case is bus or subway advertisement from display. But, Taxi have been only lapping advertisement. Because, Taxi get space restraints. Broadly speaking, Person using Gyeonggi-do to Soeul or Incheon to Soeul is 423million people. On a national basis, it's very amazing figure. However It's just so many person showing one advertisement. So people have no interest in advertisement. So I develop new advertisement system through taxi in the whole country. 254,823 car have passenger personal information and showing people needing advertisement. Also this system get geographical information. This system have high advertisement effect.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.3
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• pp.71-79
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• 2003

Existing web-based system management software solutions show some limitations in time and space. Moreover, hey possess such as shortcomings unreliable error message announcements and difficulties with real-time assistance supports and emergency measures. In order to solve these deficiencies, Wireless Remote Control System(W-RCS) was designed and implemented. W-RCS is able to manage and monitor remote systems by using mobile communication devices for instantaneous control. The implementation of W-RCS leads to these security problems as well as solutions to aforementioned issues with existing web-based system management software solutions. Therefore, this paper has focused on the security matters related to W-RCS. The security functions based on public key infrastructure include mobile device user authentication and target system access control. The W-RCS allows real-time user authentication, increases the flexibility of resource administrators and mobile device non, and provides not only uninterrupted services, but also safe mobile office environments.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.409-419
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• 2022

The purpose of this study was to investigate how the increased sedentary behavior due to COVID-19 on physical factors to maintain health. The subjects of the study were 33 office women who mainly lead a sedentary behavior. The group settings were divided into high sedentary behavior groups(n=11), middle sedentary behavior groups(n=11), and low sedentary behavior groups(n=11) according to the hours of sitting down living. There was no significant difference between the groups in the VO₂max and EPOC, the level of lactate in blood showed a significant difference immediately after exercise(p<.05) and at 15(p<.001) and 20(p<.001) minutes of recovery, and the degree of recovery was more smooth in the low sedentary behavior groups. These results suggest that the difference in time according to the degree of sedentary behavior will affect the factors for maintaining health. Therefore, it is considered necessary to minimize sedentary behavior time even in the COVID-19 situation where the time spent in a personal space increases.

• Composites Research
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• v.34 no.6
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• pp.337-344
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• 2021

In this study, the progressive failure behavior of the composite fan blade dovetail element under tensile loading is numerically investigated through finite element(FE) simulation. The accuracy of prediction by FE simulation is verified through tensile testing. The dovetail element is one of the joints for coupling the fan blade with the disk in a turbofan engine. The dovetail element is usually made of a metal material such as titanium, but the application of composite material is being studied for weight reduction reasons. However, manufacturing defects such as drop-off ply and resin pocket inevitably occur in realizing complex shapes of the fan blade made by composite materials. To investigate the effect of these manufacturing defects on the composite fan blade dovetail element, we performed numerical simulation with FE model to compare the prediction of the FE model and the tensile test results. At this time, the cohesive zone model is used to simulate the delamination behavior. Finally, we found that FE simulation results agree with test results when considering thermal residual stress and through-thickness compression enhancement effect.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.11
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• pp.1596-1602
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• 2021

Battery-operated IoT devices in IoT systems require low power consumption. In general, IoT devices enter a sleep state synchronously to reduce power consumption. A problem arises when an IoT device has to handle asynchronous user requests, as the duty cycle must be reduced to enhance response time. In this paper, we propose a new low-power-consumption scheme, called Repetitive Wake-up scheme for IoT systems of asynchronous environments such as indoor lights control. The proposed scheme can reduce power consumption by sending wake-up signals from the smartphone repetitively and by retaining the IoT device in sleep state to the smallest possible duty cycle. In the various environments with IoT devices at home or office space, we showed that the proposed scheme can reduce power consumption by up to five times compared to the existing synchronous interlocking technique.