• Journal of Astronomy and Space Sciences
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• v.34 no.4
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• pp.289-302
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• 2017

The key risk analysis technologies for the re-entry of space objects into Earth's atmosphere are divided into four categories: cataloguing and databases of the re-entry of space objects, lifetime and re-entry trajectory predictions, break-up models after re-entry and multiple debris distribution predictions, and ground impact probability models. In this study, we focused on reentry prediction, including orbital lifetime assessments, for space situational awareness systems. Re-entry predictions are very difficult and are affected by various sources of uncertainty. In particular, during uncontrolled re-entry, large spacecraft may break into several pieces of debris, and the surviving fragments can be a significant hazard for persons and properties on the ground. In recent years, specific methods and procedures have been developed to provide clear information for predicting and analyzing the re-entry of space objects and for ground-risk assessments. Representative tools include object reentry survival analysis tool (ORSAT) and debris assessment software (DAS) developed by National Aeronautics and Space Administration (NASA), spacecraft atmospheric re-entry and aerothermal break-up (SCARAB) and debris risk assessment and mitigation analysis (DRAMA) developed by European Space Agency (ESA), and semi-analytic tool for end of life analysis (STELA) developed by Centre National d'Etudes Spatiales (CNES). In this study, various surveys of existing re-entry space objects are reviewed, and an efficient re-entry prediction technique is suggested based on STELA, the life-cycle analysis tool for satellites, and DRAMA, a re-entry analysis tool. To verify the proposed method, the re-entry of the Tiangong-1 Space Lab, which is expected to re-enter Earth's atmosphere shortly, was simulated. Eventually, these results will provide a basis for space situational awareness risk analyses of the re-entry of space objects.

• Korean Institute of Interior Design Journal
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• v.15 no.4 s.57
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• pp.37-45
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• 2006

The purpose of this study is to stand assembly the meaning and function of entry space with analysing their social and cultural characteristic. The entry space is the linkable place between inner space and out space, and that is the transition place to be experienced two opposing characteristic. Till now the entry space has not taken effect as symbol needed to the resident and observer, and that has been a tendency to shrink as the minimal sign of entrance. So thus, it is in need of studying the entry space's specific and characterizing structurally as expanded function. For the purpose, this study define newly the meaning, function and composition of entry space in an apartment building, and try to find how to reinforce a resident identity. This study propose justification that the entry space isn't boxing space minimally but enforcing symbol presented clearness of composition and vital character.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.142-149
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• 2013

As we, human expand its everyday life boundary to the geosynchronous orbit, we have experienced frequent chance of the atmospheric re-entry and surface impact of space objects(satellite and space debris). Recently a satellite re-entry monitoring room in Korea has been operated to predict the time and the location of the re-entry of space objects. However, we do not have a domestic version of a numerical re-entry model for normal operation using TLE (Two line Element) information from the United States Strategic Command yet. The space information from the several space operation centers has been used to analyse the re-entry situations. In this paper, the re-entry time is calculated with TLE based on the several atmosphere models, the result is comprehensively analyzed, a new re-entry case model fitted from the result of the predicted satellite re-entry times by a new Rubber Sheet Shift Method used by the domestic satellite re-entry room is suggested.

• Journal of Space Technology and Applications
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• v.1 no.1
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• pp.23-32
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• 2021

The high-level Space Situational Awareness (SSA) objective is to provide to the users dependable, accurate and timely information in order to support risk management on orbit and during re-entry and support safe and secure operation of space assets and related services. Therefore the risk assessment for the re-entry of space objects should be managed nationally. In this research, the Software for Re-Entry Prediction of space objects (SREP) was developed for national SSA system. In particular, the rate of change of the drag coefficient is estimated through a newly proposed Drag Scale Factor Estimation (DSFE), and is used for high-precision orbit propagator (HPOP) up to an altitude of 100 km to predict the re-entry time and position of the space object. The effectiveness of this re-entry prediction is shown through the re-entry time window and ground track of space objects falling in real events, Grace-1, Grace-2, Tiangong-1, and Chang Zheng-5B Rocket body. As a result, through analysis 12 hours before the final re-entry time, it is shown that the re-entry time window and crash time can be accurately predicted with an error of less than 20 minutes.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.150-158
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• 2013

In Korea, the official monitoring of the atmospheric re-entry of satellites or space debris was initiated by the first operation of a re-entry situation analysis team for the 'Cosmos 1402' of the Soviet Union, which main body re-entered on January 23, 1983 and radio active core re-entered on February 7, 1983. After this incident, a task force team consisting Korea Astronomy and Space Science Institute (KASI), Korea Aerospace Research Institute (KARI) and other related institutes operated a situation monitoring group under the supervision of the Ministry of Science and technology (MOST) for the controlled re-entry of the Russian 'Mir' space station in 2001. The re-entry of the upper atmospheric weather satellite 'UARS' of United States had been monitored and analyzed by KASI on September 24, 2011. As the re-entry of the space object has been frequently occurred, the government officials and the experts from MEST (Ministry of Education, Science and Technology), KASI, KARI had an urgent official meeting to establish a satellite re-entry monitoring room in KASI and to give an operational authority to KASI in September 14, 2011. Under this decision, the satellite re-entry monitoring room in KASI has successfully executed the monitoring, data analyzing, official reporting, media contacting, and public announcing for the German satellite 'Roentgen' in October 2011, Russian space explorer 'Phobos-Grunt' in January 2012, Russian satellite 'Cosmos 1484' in January 2013, and European geodetic satellite 'GOCE' in November 2013 with the support from the Korean Air Force and KARI.

• Journal of the Korean Society of Safety
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• v.31 no.6
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• pp.84-92
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• 2016

Since the mankind started its space mission, the number of artificial space objects has been increasing exponentially. It contains not just the space machines which are in use but the machines which are out of order. Meantime, those dead machines are being a serious danger, a real threat to human's lives and property because of it could re-enter into the earth's atmosphere and fall to the ground causing mega-disaster. As the number of space activities gets growing so far, the re-entry of the space objects will be a lot more happened in the future. Therefore, not just natural space object like asteroids but the artificial space object like artificial satellite and space station can cause the disaster by falling to the ground. To protect our nation and our property, the government has set up the space disaster management center in Korea astronomy and Space science Institute. In this study, we surveyed public's recognition of the space object's re-entry situation and analyzed it to contribute building national space disaster management policy.

• Korean Institute of Interior Design Journal
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• v.15 no.1 s.54
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• pp.106-112
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• 2006

Buildings undergo changes by various factors according as pass at time. Due to that social requests and issues form one common sense of value and this would influence the architect's design intention. In fact, the form and function of buildings have coped with transition of the common sense of value by each times. Hospital architecture is also changed in function, scale and technology since, Kwanghyewon which was the first western style hospital in Korea was established in 1885. It is changing that the social needs for hospital which was a basic function of healing to laying emphasis on the function of precaution. According to this, the change of hospital spaces means that it can promote healing environment which is expanded from the modern concept of isolation, accommodation and urban sanitation. These changed concepts were adopted limited areas in hospitals at first however, nowadays they are expanding to other areas. So, this is caused to make the image of the hospital. From this point of view, Entry space is an example to show the changes. This study is intended to determine the overall space structure of entry area and to classify and analyze the difference.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.2
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• pp.105-111
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• 2013

Radiative heating phenomena occurring in planetary entry flights are reviewed for the purpose of educating those who are not familiar with the problem. How the radiative heat transfer rates to the Apollo entry vehicle were measured and analyzed are first described. Next, the effects of thermo-chemical non-equilibrium on radiation are summarized. Then the radiation problems in entry flights into other planets are reviewed. Finally, unsolved problems are enumerated.

• Journal of the Ergonomics Society of Korea
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• v.35 no.5
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• pp.425-437
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• 2016

Objective:The objective of this study is to develop an ergonomic toilet system along with constituent facilities that can be used with the front-entry sitting method when transferring from wheelchair to the toilet stool, instead of using the back-entry sitting method which is currently used. This system can offer more ease, convenience and safety for wheelchair users when using the restroom. Background: For users with disabilities, even a dedicated handicapped toilet requires maneuvering, especially when in a wheelchair. To transfer from wheelchair to the current back-entry sitting toilet, users need to get closer to the toilet and then turn or twist after erecting their body to get onto the toilet. This method induces inconvenience as well as secondary injury by falling when transferring to/from toilet. Method: To design a front-entry sitting toilet system, an ergonomics approach was applied which introduces a new design concept for people using wheelchairs. Using this toilet system, the wheelchair users don't need to turn or twist but can simply slide forward off the wheelchair directly onto the toilet stool in an easier and safer way. Results: The newly developed front-entry sitting toilet system is easier and safer for wheelchair users, and also space efficient requiring only two-thirds of the space of existing handicapped toilet. It is also usable by both individuals with disabilities and the general population. Conclusion: With the spread of the front-entry sitting toilet system developed in this study, wheelchair users can benefit from enhanced convenience and safety as well as significant restroom space savings. Additional effects can also be achieved such as improved self-esteem of people with disabilities by enabling to use the toilet on their own. Application: The newly developed front-entry sitting toilet system should enhance toilet accessibility to wheelchair users and the elderly. Introduction is needed with efforts at the national policy level and a macroscopic objective to promote the health and safety of the handicapped.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.6
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• pp.111-118
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• 2000

The design of reference trajectory with respect to drag acceleration is necessary to decelerate from hypersonic speed safely after atmosphere re-entry of space vehicle. The re-entry guidance design involves trajectory optimization, generation of a reference drag acceleration profile with the satisfaction of 6 trajectory constraints during the re-entry flight. This reference drag acceleration profile can be considered as the reference trajectory. The cost function is composed of the accumulated total heating on vehicle due to the reduction of weight. And a regularization is needed to prevent optimal drag profile from varying too fast and achieve realized trajectory. This paper shows the relations between velocity, drag acceleration and altitude in drag acceleration profile, and how to determine the reference trajectory.