• Journal of Korean Academy of Nursing
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• v.36 no.1
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• pp.45-54
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• 2006

Purpose: The purpose of this study was to explore Korean mothers' experiences of caregiving for their adult children with schizophrenia. Method: A iterative descriptive qualitative research design was used to understand and explain the caregiving experience from the perspective of mothers. The data were collected by individual in-depth interviews and one focus group interview from 11 mothers. The ages of the participants ranged from 50 to 60 years old and the ages of their sick children ranged from late 20s to early 40s, Results: Three major themes were identified from qualitative thematic analysis: (a) 'emotional debris from the disease,' (b) 'the disease that makes mothers dumb' (c) 'space of rational reason,' Conclusions: This study would provide health care professionals insights in establishing intervention for mothers by deeply understanding the process of recognition and acceptance of their children with schizophrenia.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.51.1-51.1
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• 2016

We revisited a recent dust emission observed at a main-belt asteroid P/2010 A2 in terms of dynamical properties of dust particles and large fragments. This is a continued research that we made a presentation at the Korean Astronomical Society 2016 Spring Meeting, but we have strengthened the dynamical analysis of the ejecta to afford the conclusive evidence for the enigmatic phenomenon. We thus constructed a model to reproduce the morphology of the dust cloud based on the dust dynamics, and succeeded in reproducing the observed morphologies in different epochs over several years. For further analysis, we reconstructed the proper motion of large fragments with respect to the dust emission source estimated from our dust model. We found that (i) the dust cloud morphologies and (ii) observed trajectories of fragments are reasonably explained only when we assumed that both were ejected from a position where no object was detected from any observations. This result suggests that the original body was shattered by an impact, leaving only debris into space. In this presentation, we will compare our results with impact laboratory studies and provide an impact interpretation of the P/2010 A2 activity.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.2
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• pp.54-58
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• 1995

1957년 인공위성의 효시가 되는 스프티닉 1호 발사이래 1994년 현재까지 약 4,000회로 추정되는 각종통신 측지 첩보 및 실험 위성 등의 발사로 지구 적도상공 36,000Km의 정지궤도 이하의 공간에는 수많은 퇴역위성, 소아마비위성(부분기능고장위성)과 더불어 발사로켓트 상단의 위성 격납용기인 내연성의 훼 어링(Fairing)의 탈락파련(Fragment)등으로 혼재된 부유물은 약 4,000톤으로 예상되며 이중 95%가 쓸모 없는 우주 쓰레기에 해당된다고 보고 있다. 여기서, 우주쓰레기의 정의는 "현재와 장래에도 유용한 목적에 이용되지 못하는 인공물체"로서 크기 로는 10여미터로 부터 산화된 연료 분사개스의 수미크론의 분진으로까지 광범위하다. 그러나, 본고에서는 우주 활동에 악영향을 끼칠수 있는 대량으로 산재된 밀리미터에서 쎈티미터의 크 기의 고속 운동 에너지를 지닌 쓰레기 조각(Debris)을 고찰해 보고자 한다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.300-305
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• 2004

A preliminary study on. field emitter array cathodes was conducted aiming at applying for electrodymanic tether (EDT) propulsion systems. The EDT propulsion systems are assumed to use for active removal systems of post-mission spacecraft, which would otherwise become space debris. A survey on field emit-ter array cathode technology was conducted, and it showed that carbon nanotube (CNT) emitters are suit-able to EDT application. Trial fabrications and evaluation tests of CNT emitters were conducted, which demonstrated a target emission current density of 10 ㎃/$\textrm{cm}^2$. It was found out that the most important technical issue for developing CNT emitters is to improve the performance against voltage breakdown between the emitter and the opposite electrode.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.56.3-56.3
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• 2021

In a ΛCDM universe, most galaxies are believed to evolve by mergers and accretions. The debris resulting from such processes remains faint and/or diffuse structures, such as tidal streams and stellar halos. Although these structures are a good indicator of the recent mass assembly history of galaxies, they have the disadvantage of being difficult to observe due to their low surface brightness (LSB). To recover these LSB features by reducing the photometric uncertainties introduced by the optics system, we attempt to develop an optimized telescope, called a linear astigmatism free-three mirror system, that minimizes the loss and scattering of light within the telescope. With that prototype, we observe NGC 5907, known as a nearby galaxy with a fabulous loop structure(s), to inspect its performance. After a dedicated data reduction process, including flat-fielding with dark sky flat and sky subtraction, our observation reaches a 1σ surface brightness limit of μlim,r ≃ 28.3 mag arcsec-2 in 10×10 arcsec boxes. We finally identify a single tidal stream that is likely the remnant of a nearly disrupted galaxy. This finding emphasizes that the capability of LSB detection with our telescope is comparable to that of much larger telescopes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.1
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• pp.63-70
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• 2017

In this paper, we design and fabricate a de-orbiter using drag-sail and evaluate deployment characteristics. Without employing an actuator to deploy, the de-orbiter is activated by the SMA wire based the release mechanism and driven by the restoring force of the tape-spring. For efficient storage and deployment of drag-sail, an origami method of original ISO flasher is chosen and low priced mylar film is used as the material of the drag-sail. In addition, through the fault tree analysis method which is one of the one-shot device reliability evaluation methods, we confirm the reliability of the de-orbiter(0.997572) and the Roller failure has the highest criticality. Finally, we find feasibility of the proposed de-orbiter through the deployment demonstration of drag-sail.

• Journal of Advanced Navigation Technology
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• v.17 no.1
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• pp.80-89
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• 2013

The amount of object which reenter the Earth's atmosphere has been increasing after the Sputnik I launch in October 1957. Most of reentry objects were incinerated by aerodynamic heating so they hardly survive. But they may incur casualties and widespread property damages if they survive and fall to surface. The amount of reentry objects, such as Satellite, Rocket Booster, Pressure Tank, ISS shows continued growth as byproduct of space activities. Most of the re-entry objects are incinerated at between altitude of 50km~80km and 10%~40% of the objects are surviving and falling to the ground. Therefore, this paper try to piece together the reentry event and analysis the survival characteristics of re-entry object.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.1
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• pp.55-70
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• 2003

Ammunition magazine, which is installed on the ground, has difficulty in protecting from the external attack, and accidental explosion should cause great damage to the life and property. For these reasons, it is needed to develop underground magazine that it has the advantages of safety, security and maintenance. This paper introduce the design case for blasting facilities, which should resist blasting pressure, as well as layout of underground magazine, which takes a safety for explosion and a working space of loading/unloading machine into consideration. On the layout, in case of ${\bigcirc}{\bigcirc}$ underground magazine, put three storage chambers in position almost parallel with principle stress direction, where less effected on discontinuity and hard rock area. Also, secured safe distance according to safety criteria of the Defense Ministry, and verified suitable layout by trace simulation for loading/unloading machine on working stage. Blasting design was performed on evaluation of maximum blast pressure between donar and acceptor chambers, and design condition for blast door, valve, etc. Diminution facilities against explosion, such as thrust block or debris trap, determined its size after plan in accordance with blasting criteria and calculation by structural analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.11
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• pp.1033-1041
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• 2011

In this paper, a collision avoidance maneuver frequency for the KOMPSAT-2 and the KOMPSAT-5 is analyzed. For the statistical prediction of the avoidance maneuver frequency, mission orbits, responsive time, accepted collision probabilities, and positional uncertainties of primary and secondary objects are considered. In addition, the collision avoidance maneuver frequency of the KOMPSAT-2 is compared to the case that NORAD catalog during one year is used to calculate that of the KOMPSAT-2. As a result, the collision avoidance maneuver frequency is one per year on average and effective factors on the statistical prediction of the avoidance maneuver frequency are investigated. Efforts to improve its prediction accuracy are also discussed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.12
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• pp.1037-1048
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• 2018

In this paper, we investigated the international guidelines and actual disposal maneuver cases to prepare KOMPSAT-2 post mission disposal. And then, disposal maneuver plan was established using current propellant of KOMPSAT-2 and verification was also performed to find out whether the international guidelines are satisfied. As a result, the lifetime of KOMPSAT-2 was 3.6 years when 45kg propellant was used to decrease perigee altitude to 300km. And if more than 14.5kg propellant consumed for same strategy, KOMPSAT-2 can satisfy the international guidelines. Finally, re-entry survivability analysis was performed and it represented that heat resistant objects, such as propellant tank and reaction wheel, could be survived but total ground casualty probability was less than international guidelines.