• Korean Journal of Agricultural and Forest Meteorology
• /
• v.7 no.1
• /
• pp.4-14
• /
• 2005

CarboKorea and HydroKorea are the domestic projects aiming to improve our understanding of carbon and water cycles in a typical Korean forest located in a complex terrain with a watershed connected to large rivers. The ultimate goal is to provide a nowcasting of these cycles for the whole Peninsula. The basic strategy to achieve such goal is through the inter- and multi-disciplinary studies that synthesize the in-situ field observation, modeling and remote sensing technology. The challenge is the fact that natural ecosystems are nonlinear and heterogeneous with a wide range of spatio-temporal scales causing the variations of mass and energy exchanges from a leaf to landscape scales. Our paradigm now shifts from temporal variation at a point to spatial patterns and from spatial homogeneity to complexity of water and carbon at multiple scales. Yet, a large portion of our knowledge about land-atmosphere interactions has been established based on tower observations, indicating that the development of scaling logics holds the key to the success of CarboKorea and HydroKorea. Here, we review the pioneering work of FIFE (First ISLSCP Field Experiment) on scaling issues in a temperate grassland and discuss the lessons from it for the application to Gwangneung forest site.

• Mass Spectrometry Letters
• /
• v.1 no.1
• /
• pp.13-16
• /
• 2010

The active components in a plant extract can be represented as mass profiles. We introduce here a new, multi-compound discovery method known as Scaling of Correlations between Activity and Mass Profiles (SCAMP). In this method, a correlation coefficient is used to quantify similarities between the extract activity and mass profiles. The method was evaluated by first measuring the anti-oxidation activity of eleven fractions of an Astragali Radix extract using DPPH assays. Next, 15 T Fouriertransform ion cyclotron resonance (FT-ICR) MS was employed to generate mass profiles of the eleven fractions. A comparison of correlation coefficients indicated two compounds at m/z 285.076 and 286.076 that were strong antioxidants. Principal component analyses of these profiles yielded the same result. FT-ICR MS, which offers a mass resolving power of 500,000, was used to discern isotopic fine structures and indicated that the molecular formula corresponding to the peak at m/z 285.076 was $C_{16}H_{13}O_5$. SCAMP in combination with high-resolution MS can be applied to any type of mixture to study pharmacological activity and is a powerful tool for active compound discovery in plant extract studies.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.8
• /
• pp.877-885
• /
• 2005

The Froude scaling between the prototype and the model was tried to estimate the necessary ventilation rate for non-isothermal concentrated fume from the semi-closed inner space. Based on the non-dimensional similitude equations derived from the Zukoski plume rise analysis, the scaling experiments were done to verify the relationship of the non-dimensional energy release rate and the non-dimensional mass flow rate by using two different scaled volume models, model A ($1\;m{\times}1\;m{\times}1\;m$) and model B ($0.5\;m{\times}0.5\;m{\times}0.5\;m$). The experimental results showed that the theoretical similitude between the models is acceptable for the prediction of ventilation rate of the concentrated fume. The maximum energy release rate used for the experiments was $20\;kW/m^3$. In the experimental range, the similitude between the energy release rate and the ventilation mass flow rate was well defined and the necessary ventilation rates were 20-30% higher than the stoichiometric ventilation mass flow rate. Based on results of current study, the design of the local air ventilation system can be improved by correcting the effects of buoyancy and diffusion of the non-isothermal concentrated fume.

• Computational Structural Engineering
• /
• v.8 no.3
• /
• pp.103-111
• /
• 1995

Evaluating nonlinear response of a MDOF system under dynamic stochastic loads such as seismic excitation usually requires excessive computational efforts. To alleviate this computational difficulty, an approximation is developed in which the MDOF inelastic system is replaced by a simple nonlinear equivalent system(ENS).Me ENS retains the most important properties of the original system such as dynamic characteristics of the first two modes and the global yielding behavior of the MDOF system. The system response is described by the maximum global(building) and local(interstory) drifts. The equivalency is achieved by two response scaling factors, a global response scaling factor R/sub G/, and a local response scaling factor R/sub L/, applied to the responses of the ENS to match those of the original MDOF system. These response scaling factors are obtained as functions of ductility and mass participation factors of the first two modes of structures by extensive regression analyses based on results of responses of the MDOF system and the ENS to actual ground accelerations recorded in past earthquakes. To develop the ENS with two response scaling factors, Special Moment Resisting Steel Frames are considered. Then, these response scaling factors are applied to the response of ENS to obtain the nonlinear response of MDOF system.

• Steel and Composite Structures
• /
• v.27 no.1
• /
• pp.123-133
• /
• 2018

Steel-concrete-steel (SCS) sandwich composite structure with corrugated-strip connectors (CSC) has the potential to be used in buildings and offshore structures. In this structure, CSCs are used to bond steel face plates and concrete. To overcome executive problems, in the proposed system by the authors, shear connectors are one end welded as double skin composites. Hence, this system double skin with corrugated-strip connectors (DSCS) is named. In this paper, finite element model (FEM) of push-out test was presented for the basic component of DSCS. ABAQUS/Explicit solver in ABAQUS was used due to the geometrical complexity of the model, especially in the interaction of the shear connectors with concrete. In order that the explicit analysis has a quasi-static behavior with a proper approximation, the kinetic energy (ALLKE) did not exceed 5% to 10% of the internal energy (ALLIE) using mass-scaling. The FE analysis (FEA) was validated against those from the push-out tests in the previous work of the authors published in this journal. By comparing load-slip curves and failure modes, FEMs with suitable analysis speed were consistent with test results.

• Smart Structures and Systems
• /
• v.6 no.1
• /
• pp.57-72
• /
• 2010

This paper presents the most significant results obtained within a broad-ranging experimental program aiming to evaluate both the effectiveness and the robustness of a Base Isolation (BIS) and a Tuned Mass Damper (TMD) combined control strategy (BI & TMD). Following a brief description of the experimental model set-up and the adopted kinematic scaling technique, this paper describes the identification procedures carried out to characterize the system''s model. The dynamic response of a small-scale model to recorded earthquake excitations, which has been scaled by using the Buckingham pi-theorem, are later presented and discussed. Finally, the effectiveness and robustness of the combined control strategy is evaluated by comparing the model's dynamic response. In particular, reduction in relative displacements and absolute accelerations due to the application of different mass damping systems is investigated.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.335-339
• /
• 2015

Using black hole masses which span $10^5-10^{10}M_{\odot}$, the distribution of galaxies in the (host spheroid stellar mass)-(black hole mass) diagram is shown to be strongly bent. While the core-$S{\acute{e}}rsic$ galaxies follow a near-linear relation, having a mean $M_{bh}/M_{sph}$ mass ratio of ~0.5%, the $S{\acute{e}}rsic$ galaxies follow a near-quadratic relation. This is not due to offset pseudobulges, but is instead an expected result arising from the long-known bend in the $M_{sph}{-{\sigma}}$ relation and a log-linear $M_{bh}{-{\sigma}}$ relation.

• Journal of the Korean earth science society
• /
• v.34 no.5
• /
• pp.407-414
• /
• 2013

This study presents the global star formation efficiency (SFE) of 272 local star-forming galaxies based on the HI gas mass, stellar mass, star formation rate (SFR), and morphology. The SFE increases as the stellar mass increases while the specific SFR decreases. The SFE is enhanced for galaxies with large H$\acute{a}$ equivalent widths, which is primarily due to the large SFR, not due to the large available amount of gas. The SFE is also enhanced by a factor of ~2 for merging systems compared to the normal spirals, showing that the merger-induced high pressure and density environment are crucial for the active star formation. Based on the SFR scaling relation, I present a SFR calibration formula using the HI gas mass.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2006.05a
• /
• pp.222-226
• /
• 2006

The purpose of this study is to analyze both the design and off design performance simulation of the PW206C turbo shaft engine used in the development of the smart UAV (Unmanned Ariel Vehicle) by KARI(Korean Aerospace Research Institute). Its mainly aims to investigate performance behavior at the un-installed and installed conditions. The ways employed to be able to analyze the performance extensively were mainly carried out by comparison of performance simulation results from both the commercial program 'GASTURB 9' using compressor maps generated by Genetic algorithms (GAs) or Scaling Method, and the engine manufacturer's program 'EEPP'. Off-design performance analysis was performed through matching of both mass flow and work between engine components. The set of performance simulations of the developed analytical models was performed by a commercial program package (GASTURB 9) that provides great flexibility in the choice of independent variables of the overall system. The results from the simulations are used to compare turbo shaft engine (PW206C) performance data obtained by the EEPP. At un-installed condition, it was found that the results with the compressor map generated by GAs were relatively agreed well than those with the compressor map generated by the Scaling Method. The performance calculation results using the compressor map generated by GAs were compared at un-installed condition and installed conditions with ECS-off and ECS-Max in variation of altitude, gas generator speed and flight speed.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.9
• /
• pp.74-81
• /
• 2002

Recently tube hydroforming has been widely applied to the automotive industries due to its several advantages over conventional methods. In this paper, attention is paid to comparison of an implicit and an explicit finite element method widely used for numerical simulation of a hydroforming process. For an explicit FEM, a huge amount of computational time is required because of the very small time increment to solve a quasi-static problem. Hence, when an explicit FEM is used fDr a hydroforming process, it is general to convert the real problem to a virtual problem with a different processing time and mass density by appropriate scaling factor. However it is difficult to figure out how large the scaling should be adopted enough to ignore the dynamic effects and maintain the desired accuracy. In this paper, the comparison of the results obtained from both methods focus on the accuracy of the predicted geometrical shape and the stress with various scaling factors which are applied to analyze hydroforming process of an automobile lower arm.