• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.105.1-105.1
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• 2012

Moon and Mars have been explored by landers and rovers. Apollo missions landed five times on Lunar surface, and various rovers, including Curiosity landed and explored Mars. The selection of landing site have to be considered engineering and scientific side: the landing site to be available to land stably? the obstacle is not around the rover such as rocks and pothole? the landing site is valuable with scientific? And then landing site have to be the place which is satisfied two objects. We search the information about landing sites of Moon and Mars, and compile the conditions of landing sites. We expect that these data are useful when the landing site of Moon or Mars for Korean mission is selected.

• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1315-1320
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• 2016

The present study aims to predict the heat transfer characteristics around a square cylinder with different corner radii using multivariate adaptive regression splines (MARS). Further, the MARS-generated objective function is optimized by particle swarm optimization. The data for the prediction are taken from the recently published article by the present authors [P. Dey, A. Sarkar, A.K. Das, Development of GEP and ANN model to predict the unsteady forced convection over a cylinder, Neural Comput. Appl. (2015) 1-13]. Further, the MARS model is compared with artificial neural network and gene expression programming. It has been found that the MARS model is very efficient in predicting the heat transfer characteristics. It has also been found that MARS is more efficient than artificial neural network and gene expression programming in predicting the forced convection data, and also particle swarm optimization can efficiently optimize the heat transfer rate.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.31.2-31.2
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• 2018

미국 유타주 유타사막에 설치된 MDRS(Mars Desert Research Station)는 미국의 비영리기구인 화성학회(The Mars Society)에서 운영하는 화성탐사연구기지다. 화성학회는 1998년 우주비행사, 천문학자, 과학자 4000여명이 모여 만든 비영리연구단체다. 2001년 미국 유타주에 문을 연 MDRS에서는 토양 미생물 검출실험, 태양에너지 조리실험, 영구동토층 연구, 해빙 연구, 드론 정찰 및 지도 작성 등 인류가 화성에 도착했을 때 실제 수행할 연구들을 진행하고 있다. tVN <갈릴레오 : 깨어난 우주> 촬영 차 MDRS에 머물며 과학실험을 수행한 사례를 공유하고 이를 통해 천문학 및 우주탐사에 대한 대중화 방안에 대해 논의해 보고자 한다.

• Structural Engineering and Mechanics
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• v.60 no.3
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• pp.471-488
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• 2016

This study predicts the strength of rotary brace damper by analyzing a new set of probabilistic models using the usual method of multiple linear regressions (MLR) and advanced machine-learning methods of multivariate adaptive regression splines (MARS), Rotary brace damper can be easily assembled with high energy-dissipation capability. To investigate the behavior of this damper in structures, a steel frame is modeled with this device subjected to monotonic and cyclic loading. Several response parameters are considered, and the performance of damper in reducing each response is evaluated. MLR and MARS methods were used to predict the strength of this damper. Displacement was determined to be the most effective parameter of damper strength, whereas the thickness did not exhibit any effect. Adding thickness parameter as inputs to MARS and MLR models did not increase the accuracies of the models in predicting the strength of this damper. The MARS model with a root mean square error (RMSE) of 0.127 and mean absolute error (MAE) of 0.090 performed better than the MLR model with an RMSE of 0.221 and MAE of 0.181.

• Nuclear Engineering and Technology
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• v.31 no.3
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• pp.344-363
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• 1999

A multi-dimensional thermal-hydraulic system analysis code, MARS 1.3.1, has been developed in order to have the realistic analysis capability of two-phase thermal-hydraulic transients for pressurized water reactor (PWR) plants. As the backbones for the MARS code, the RELAP5/MOD3.2.1.2 and COBRA-TF codes were adopted in order to take advantages of the very general, versatile features of RELAP5 and the realistic three-dimensional hydrodynamic module of COBRA-TF. In the MARS code, all the functional modules of the two codes were unified into a single code first. Then, the source codes were converted into the standard Fortran 90, and then they were restructured using a modular data structure based on "derived type variables" and a new "dynamic memory allocation" scheme. In addition, the Windows features were implemented to improve user friendliness. This paper presents the developmental work of the MARS version 1.3.1 including the hydrodynamic model unification, the heat structure coupling, the code restructuring and modernization, and their verifications.their verifications.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.112-122
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• 2014

A main steam line break (MSLB) test at the ATLAS facility was simulated using the best-estimate thermal-hydraulic system code, MARS-KS. This has been performed as an activity at the third domestic standard problem for code benchmark (DSP-03) that has been organized by Korea Atomic Energy Research Institute (KAERI). The results of the MSLB experiment and the MARS input data prepared for the previous DSP-02 using the ATLAS facility were provided to participants. The preliminary MSLB simulation using the base input data, however, showed unphysical results in the primary-to-secondary heat transfer. To resolve the problems, some improvements were implemented in the MARS input modelling. These include the use of fine meshes for the bottom region of the steam generator secondary side and proper thermal-hydraulics calculation options. Other input model improvements in the heat loss and the flow restrictor models were also made and the results were investigated in detail. From the results of simulations, the limitations and further improvement areas of the MARS code were identified.

• The Korean Journal of Quaternary Research
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• v.23 no.1
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• pp.38-41
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• 2009

Results from the most recent decade of Mars' missions to Mars highlight a liquid water and water-ice sculpted landscape. Evidence includes layered sedimentary sequences with weathered outcrops, debris flows, fluvial valleys, alluvial fans, deltas, glacial and periglacial landscapes, and geochemical/mineralogical signatures of aqueous activity, including the formation of sulfates and clays, and the leaching and deposition of elements such as potassium, thorium,and iron. Such evidence indicates weathered zones and possible paleosols in stratigraphic sequences, transport of water and rock materials to sedimentary basins, and the possible formation of extensive transient lakes and possibly transient oceans on Mars. This new evidence is consistent with Viking-era geologic investigations that reported magmatic-driven flooding, ponding to form large water bodies in the northern plains, and transient (tens of thousand of years) hydrological cycles. It may even indicate aqueous activity at present. Both endogenic (magmatic driven) and exogenic (both impact cratering and changes in orbital parameters) have influenced paleohydrologic and environmental change on Mars. Abundance of water and dynamic activity would be decisively important for the possibility of past and present life on Mars.

• Journal of Korean Elementary Science Education
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• v.40 no.1
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• pp.1-12
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• 2021

This study investigated pre-service elementary teachers' understanding of the planetary revolution movement of Mars and their explanatory models to show how the Sun-Earth-Mars system worked. An assessment item set using five celestial maps drawn from the Stellarium was designed to probe pre-service teachers' understanding of the prograde-retrograde motion of Mars. Among 23 participants, only four showed scientifically accurate understanding of Mars movement and drawing correct explanatory models for the planetary movement. Even the pre-service teachers who construed correctly prograde and retrograde motions of Mars showed a clockwise movement model due to their intuitive perceptions of Mars movement data from the celestial maps. Pre-service teachers with poor understanding of planetary movement also showed weak explanatory models due to their limited observation or lower spatial thinking. Although the planetary motion is not an easy topic for pre-service elementary teachers, it can be argued if the alternative approach, such as using appropriate observational data of a planet and changing the frames of reference between Earth-based view and Space-based view, is employed effectively in teaching planetary motion, pre-service teachers can reach the upper level of leaning planetary motion in terms of the planet's revolution.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.56-68
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• 2016

Extensive researches have been carried out for enhancing the safety of nuclear power plants and, especially, the development of passive cooling systems, such as passive containment cooling system (PCCS) and passive residual heat removal system, is increasingly important, where condensation is a crucial heat transfer mechanism. Recently, Ahn & Yun et al. developed a horizontal in-tube condensation heat transfer model as one of the activities for the PCCS development. In this work, we implemented the Ahn & Yun 's condensation heat transfer model into the MARS code and assessed it using the PASCAL experimental data. Based on the results of the assessment, we identified the limitations of the Ahn & Yun 's model and suggested a modified Ahn & Yun 's model, and assessed the model using various experimental data.

• Journal of Astronomy and Space Sciences
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• v.29 no.4
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• pp.337-342
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• 2012

In this study, the transient second or third layer on the topside of the Martian ionosphere were investigated with the most recently released Mars advanced radar for subsurface and ionospheric sounding/Mars Express data obtained from January 2010 to September 2011 to study the correlation between these topside additional layers and surface magnetic fields, solar zenith angle and solar activities. When examining the zones where the topside layer appeared, the occurrence rate of the topside layer was low at the areas with a strong Martian crustal magnetic field as observed by the Mars global surveyor. The occurrence rate of additional layers on the Martian topside ionosphere decreases as the solar zenith angle increases. However, these layers appeared significantly near the terminator of which solar zenith angle is $90^{\circ}$. In comparison between F10.7 which is the index of solar activities and the occurrence rate of the topside layer by date, its occurrence rate was higher in 2011 than in 2010 with less solar activities. The result of this study will contribute to better understanding of the environments in the topside of the ionosphere through the correlation between the various conditions regarding the Martian ionosphere and the transient layer.