• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.393-395
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• 1999

본 논문에서는 RFC 2022에서 제안한 MARS 모델을 기반으로 하여 ATM 망에서 다중의 멀티캐스팅 서버(MCS)를 이용한 두 가지 멀티캐스팅 모델을 제안하였다. 또한 멀티캐스트 주소 해석 서버(MARS) 방안에 기반한 기존의 두 가지 모델과 1:1 VC 및 1:n VC 자원의 소비량을 정량적으로 비교하였다. 하나의 멀티캐스트 그룹을 보다 작은 부그룹들로 나누어 관리하는 "다중 MCS-그룹 분할 모델"이 "다중 MCS-그룹 비 분할 모델"보다 1:n VC 자원 소비량은 많은 단점이 있으나 송신 노드와 수신 그룹 멤버들 사이에 형성되는 멀티캐스트 트리의 종단간 평균 지연 시간을 감소시킬 수 있는 여지를 제공하는 장점이 있다. 있는 여지를 제공하는 장점이 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.133-137
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• 2001

급속한 인터넷의 확산으로 인해 다양한 멀티미디어 응용 서비스들이 등장하였다 영상회의, 인터넷 방송, VOD등과 같은 실시간 인터넷 멀티미디어 서비스들은 고속의 데이터 전송과 QoS 그리고, 멀티캐스트를 요구한다. 인터넷의 하부구조인 ATM 망에서 IP 멀티캐스트를 지원하기 위한 방안으로 MARS가 제안되었으며, 또한 최선형 서비스 기반의 인터넷에서 서비스의 품질을 보장하기 위하여 자원예약 신호 프로토콜인 RSVP가 제안되었다. 본 논문에서는 단일 MCS기반의 MARS가 가지는 문제점들을 보완하기 위해 2개 이상의 MCS를 가지는 다중 MCS MARS기반의 ATM 망에서 클러스터 내의 ATM 호스트가 특정 IP 멀티캐스트 그룹에 가입할 경우 MARS가 종단간 전송지연을 최소화하는 MCS를 할당하여 송신자와 수신자간에 최소의 전송지연을 가지도록 하고, MARS가 Resv 메시지를 수신했을 때, 자원예약 메시지를 처리할 수 있도록 그 기능이 확장된 MARS는 유지하고 있는 MCS 관리 테이블을 참조하여 MCS를 재 선정함으로써 인터넷 서비스의 QoS를 유지하고, MARS와 MCS의 처리 부하를 줄일 수 있는 방안을 제시하고자 한다.

• Geomechanics and Engineering
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• v.7 no.4
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• pp.431-458
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• 2014

Construction of a new cavern close to an existing cavern will result in a modification of the state of stresses in a zone around the existing cavern as interaction between the twin caverns takes place. Extensive plane strain finite difference analyses were carried out to examine the deformations induced by excavation of underground twin caverns. From the numerical results, a fairly simple nonparametric regression algorithm known as multivariate adaptive regression splines (MARS) has been used to relate the maximum key point displacement and the percent strain to various parameters including the rock quality, the cavern geometry and the in situ stress. Probabilistic assessments on the serviceability limit state of twin caverns can be performed using the First-order reliability spreadsheet method (FORM) based on the built MARS model. Parametric studies indicate that the probability of failure $P_f$ increases as the coefficient of variation of Q increases, and $P_f$ decreases with the widening of the pillar.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.767-768
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• 2015

Spectra of reflected sunlight from Mars and Jupiter are presented. They were obtained from an educational 1-D array spectrograph covering almost a full range of visible wavelengths, 200~900 nm with 1 nm spectral resolution. The question was whether a spectral difference could be obtained between that of terrestrial planets and gas planets with an educational spectrograph. It was installed in a 12-inch reflecting telescope at the Korea Science Academy of KAIST in Busan. Both spectra show clear absorption lines of reflected sunlight. They shows differences oin line presence, but are not very significant. This work means that the spectrograph successfully observed the reflected spectra of planets and can detect differences in spectra in terms of the absence and presence of absorption lines of planets.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.341-346
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• 2004

Motion of a bubble inside narrow tube is numerically studied. The numerical code assumes axi-symmetric incompressible flow field. The surface of the bubble is captured by VOF (Volume Of Fluid) method, and it is advected by MARS (Multiphase Advection and Reconstruction Scheme). Air bubble inside water is first studied, and it was found that a strong vortex, which is induced by the pressure difference caused by the surface tension, is formed at the rear part of the bubble. Then flow parameters are parametrically varied to understand the correlation between the bubble shape, the bubble velocity, and the flow parameters. The parametric study revealed that the aspect ratio of the bubble mainly depends on We number, and the oscillation of the bubble speeds is dependent on Re number.

• Nuclear Engineering and Technology
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• v.44 no.5
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• pp.535-542
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• 2012

A sodium-cooled demonstration fast reactor with the KALIMER-600 as a reference plant is under design by KAERI. The safety grade decay heat removal system (DHRS), which is important to mitigate design basis accidents, was changed in the reactor design. A loss of heat sink and a vessel leak in design basis accidents were simulated using the MARS-LMR system transient analysis code on two plant systems. In the analyses, the DHRS of KALIMER-600 had a weakness due to elevation of the overflow path for the DHRS operation, while it was proved that the DHRS of the demonstration reactor had superior heat transfer characteristics due to the simplified heat transfer mechanism.

• Advances in aircraft and spacecraft science
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• v.9 no.5
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• pp.401-414
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• 2022

In the present paper, the optimal selection of batteries for an electric pump-fed hybrid rocket engine is analyzed. A two-stage Mars Ascent Vehicle, suitable for the Mars Sample Return Mission, is considered as test case. A single engine is employed in the second stage, whereas the first stage uses a cluster of two engines. The initial mass of the launcher is equal to 500 kg and the same hybrid rocket engine is considered for both stages. Ragone plot-based correlations are embedded in the optimization process in order to chose the optimal values of specific energy and specific power, which minimize the battery mass ad hoc for the optimized engine design and ascent trajectory. Results show that a payload close to 100 kg is achievable considering the current commercial battery technology.

• Publications of The Korean Astronomical Society
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• v.38 no.2
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• pp.37-57
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• 2023

"Are we alone in the universe?" is the fundamental question of mankind. To search for the life signatures in the universe, there have been a lot of researches and space explorations, especially in our solar system. In this review paper, we introduce the definition and characteristics of the "biosignature". The current situations and future plans for searching for biosignatures in our solar system are reviewed, especially at Venus, Mars, and Ocean Worlds such as Europa and Enceladus where life signatures are more likely to exist than in other places in the solar system. Finally, we discuss the opportunities and strategies for the Korean scientific society to participate in searching for biosignatures in the solar system.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.363-364
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• 2004

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.361-362
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• 2004