• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.3
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• pp.240-246
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• 2012

The supply and use of exhaust heat recovery ventilation system as effective energy saving equipment has been increasing steadily. The exhaust heat recovery ventilation system can be installed at ceiling of balcony or emergency space. However, ventilation system can not be installed at emergency space because where have to remain as empty space by law. Therefore, the proper installation space of ventilation system is needed. In this study, to install heat recovery ventilation system in the light weight wall, thickness of heat exchanger was assembled below 140 mm. One or two paper heat exchangers were installed in the ventilation system. The efficiency of heat recovery was analyzed through performance experiment on case of cooling and heating mode.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.2
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• pp.83-89
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• 2021

The extended Kalman filter (EKF) is widely used for global navigation satellite system (GNSS) applications. It is difficult to obtain precise positions with an EKF one-way (forward or backward) filter. In this paper, we propose an EKF smoother to improve the positioning accuracy by integrating forward and backward filters. For the EKF smoother experiment, we performed PPP using GNSS data received at the DAEJ reference station for a month. The effectiveness of the proposed approach is validated with multi-GNSS kinematic PPP experiments. The EKF smoother showed 35%, 6%, and 22% improvement in east, north, and up directions, respectively. In addition, accurate tropospheric zenith total delay (ZTD) values were calculated by a smoother. Therefore, the results from EKF smoother demonstrate that better accuracy of position can be achieved.

• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.174-180
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• 2015

There are currently many research papers on the knowledge, perceptions and actions of radiation-related staff, but hardly any papers on radiation major students in college who are to be staff members of radiation related jobs in the future. It is of course important to understand the perceptions of staff working on the lines and change their knowledge and perceptions, but in the long term it seems more efficient to understand those who are in the stage of being educated to be staff members-their knowledge and perception of radiation so that ultimately they can attain the right kind of understanding. Therefore the aim of this study is to grasp the pre-radiation staff's basic concept of radiation and space dose, their understanding of radiation safety based on this, and whether there is a change in their perception before and after the space dose measurement experiment; in the end this is to see if the space dose measurement experiment is effective in changing perception on radiation safety. This study took as its subject 64 students majoring radiation in college, I.e. pre-radiation staff members, and gauged their basic conceptualization of radiation, understanding of space dose, and understanding of radiation safety; in the X-ray room within the department the students were asked to measure space dose for themselves, so as to see whether there was a change in their understanding of radiation safety before and after the experiment, according to their understanding of the basic concept of radiation and of space dose. As a result of the space dose measurement experiment, students' increased basic knowledge of concept of radiation and understanding of the dangers of space dose were noteworthy, and accordingly their understanding of radiation safety became stricter and more conservative. In spite of this, their work ethic stayed in the lead of their understanding of radiation safety; this implies the need of a more departmentalized safety education program. Therefore instead of safety education that simply uses visual-audial material in a kind of lecture, I suggest here that there be a more experiential safety education program that enables learners to try out space dose measurement experiments for themselves, a work ethic education that aims for a conventional point of view towards radiation safety as well as a stern attitude.

• Journal of Space Technology and Applications
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• v.2 no.2
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• pp.81-103
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• 2022

In this paper, the contents of the design and development process of the 6U micro-satellite Snipe (SNIPE, national name Toyosat; small scale magnetospheric and Ionospheric plasma experiment ), which was developed to observe the near-global space environment through polarization flight for the first time in Korea, were described. Snipe performs transversal flight to observe the Earth's surrounding space environment in three dimensions, and aims to simultaneously observe the space plasma density and temperature in the ionosphere, as well as temporal changes in the solar magnetic field and electromagnetic waves. In this way, it was developed by dividing it into a test certification model (EQM) and a flight model (FM) to perform the actual mission for at least six months, away from developing a cube satellite for short-term space technology verification or manpower training. Currently, Snipe, which has completed the development of a total of four FM and completed all space environment tests, is scheduled to launch 2023. In this paper, we introduce the design contents and development process of the Snipe satellite body ahead of launch, and hope that it will be a useful reference for the development of 6U-class micro-satellite for full-scale mission in Korea.

• Spatial Information Research
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• v.19 no.3
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• pp.53-62
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• 2011

Spatial information services in indoor space are an im portant application area of GIS as in outdoor space. Unlike in outdoor space, a position in indoor space is specified by a symbolic code such as room number, rather than coordinate. Therefore tracking in indoor space is no longer a prediction of coordinates but a symbolic estimation on the current position of a moving object. In this paper, we propose a framework for tracking moving objects in indoor symbolic space with RFID sensors. First, we introduce the concepts of indoor symbolic space and tracking in indoor symbolic space, and define the accessibility graph for trackable indoor symbolic space. Second, we propose a deployment method of RFID readers and a construction algorithm of accessibility graph for trackable indoor symbolic space. Third, a tracking method is proposed for moving objects in symbolic indoor space with RFID sensors. Finally, we present an implementation exmaple and the result of experiment with real data to validate the proposed method.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.75-82
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• 2004

Many researcher's efforts have made a significant advancement of space frame structure with various portion, and it becomes the most outsanding one of space structures. However, with the characteristics of thin and long term of spacing, the unstable behavior of space structure is shown by initial imperfection, erection procedure or joint, especially space frame structure represents more. This kind of unstable problem could not be set up clearly and there is a huge difference between theory and experiment. Moreover, the discrete structure such as space frame has more complex solution, this it is not easy to derive the formulation of design about space structure. In this space frame structure, the character of rise-span ratio or load mode is represented by the instability of space frame structure with initial imperfection, and snap-through or bifurcation might be the main phenomenon. Therefore, in this study, space frame structure which has a lot of aesthetic effect and profitable for large space covering single layer is dealt. And because that the unstable behavior due to variation of inner force resistance in the elastic range is very important collapse mechanism, I would like to investigate unstable character as a nonlinear behavior with a geometric nonlinear. In order to study the instability. I derive tangent stiffness matrix using finite element method and with displacement incremental method perform nonlinear analysis of unit space structure, star dome and 3-ring star dome considering rise-span $ratio(\mu}$ and load $ratio(R_L)$ for analyzing unstable phenomenon.

• Journal of Astronomy and Space Sciences
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• v.30 no.4
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• pp.335-344
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• 2013

TRiplet Ionospheric Observatory-CubeSat for Ion, Neutron, Electron & MAgnetic fields (TRIO-CINEMA) is a CubeSat with 3.14 kg in weight and 3-U ($10{\times}10{\times}30$ cm) in size, jointly developed by Kyung Hee University and UC Berkeley to measure magnetic fields of near Earth space and detect plasma particles. When a satellite is launched into orbit, it encounters ultra-high vacuum and extreme temperature. To verify the operation and survivability of the satellite in such an extreme space environment, experimental tests are conducted on the ground using thermal vacuum chamber. This paper describes the temperature control device and monitoring system suitable for CubeSat test environment using the thermal vacuum chamber of the School of Space Research, Kyung Hee University. To build the chamber, we use a general purpose thermal analysis program and NX 6.0 TMG program. We carry out thermal vacuum tests on the two flight models developed by Kyung Hee University based on the thermal model of the TRIO-CINEMA satellite. It is expected from this experiment that proper operation of the satellite in the space environment will be achieved.

• Land and Housing Review
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• v.9 no.4
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• pp.33-42
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• 2018

As a radiant heating panel gets more popularity, the need to study on evaluation method of thermal output of the panel also becomes increasing. Generally, the chamber using method is applied to evaluate the thermal output through an experiment. However, the chamber using method cannot be used due to the limitations on space and cost. EN1264 addresses the test equipment to evaluate the thermal output by using simpler experimental setup, and introduces application method in detail. However, there is not enough description of control methods to meet the experiment condition, and it is difficult to meet this when practical experiment. Therefore, this paper analysed the control error factors of when the thermal output experiment is performed. When EN1264 method is applied to evaluate the thermal output of the radiant floor heating panel, the error factor which is caused by the characteristic of test equipment cannot be removed by the control methods of chamber using method. In addition, the error factor can be occurred at the element which is located out of the control system. These possible error factors are defined as the characteristic error factors.

• KIEAE Journal
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• v.17 no.4
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• pp.33-39
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• 2017

Purpose: The use of renewable energy system is essential for building energy independence and saving energy consumption in the building sector. Among renewable energy technologies, ground source heat pump(GSHP) system is more energy-efficient and environmental-friendly than other heat source systems due to utilize stable ground heat source. However, the GSHP system requires a high initial installation cost and installation space in limited urban area, so it is difficult to have superiority in the market of heat source system. Therefore, it is necessary to develop the installation method of low-cost and improve system performance. This paper aims to evaluate the performance of double u-tube ground heat exchanger(GHX) and verify system feasibility through real-scale experiment. Method: In this study, the real-scale experiment of vertical closed-type GSHP system was conducted using double u-tube GHX and high-efficiency grout. Through the verification experiment, heat source temperature, heat exchange rate(HER) and seasonal performance factor(SPF) were measured according to the long-term operation. In addition, the feasibility analysis was conducted comparing to the single u-tube system. Result: In the results of experiment, average HER was 136.27 W/m and average SPF was 5.41. Furthermore, compared to the single u-tube, the installation cost of the developed system could be reduced about 70% in the same heating load condition.

• Journal of Space Technology and Applications
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• v.1 no.3
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• pp.319-336
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• 2021

This paper discusses the results of launch environment tests for the engineering qualification model (EQM) of nanosatellite Scale magNetospheric and Ionospheric Plasma Experiment (SNIPE) for scientific missions and lessons learned for the design of nanosatellites. SNIPE is a group of four formation-flying 6U nanosatellites with a range of payloads for missions including space weather measurement. We developed the EQM to verify the preliminary design prior to fabricating the flight model. Launch environment test of EQM was conducted for the first time in 2019, and all failures were corrected and verified at the second test conducted in 2021. A notable point of the two tests is that the nanosatellite deployer used in the first test is different from that of the second test. The second deployer has the capability to fix the internal satellite whereas the first deployer just contains and deploys the satellite. Thus actual mechanical loads the satellite receives is reduced for the second test compared to the first test. This work compares the mechanical responses of two tests and proposes general guidelines for structural design of nanosatellites.