The nonlinear simple pendulum is investigated to find the exact closed-form analytical solution, satisfying initial conditions of angular position and angular velocity. While previous numerous studies have been conducted on the nonlinear simple pendulum, the exact closed-form analytical solution still remains not available in public domain for the most general initial condition including initial angular velocity as well as initial angular displacement. In this paper, the exact closed-form analytical solution for the general initial conditions is derived using Jacobi’s elliptic function and elliptic integral. The result was verified by comparing it with previous studies and the numerical solution of the equation of motion through the Runge-Kutta integration method.

To optimize initial cooling conditions, forced-air cooling was applied to freshly harvested oak mushrooms at 2 levels (0oC for 30 minutes, at 0oC for 1 hour) followed by room cooling at 3 levels (-3oC for 1 day, 0oC for 1 day, 3oC for 1 day). After initial cooling, the oak mushrooms were packaged with PVC film, then held in a storage room at 1oC for 6 weeks. Quality characteristics and percentage marketability were then investigated. As a control, Mushrooms were placed in storage with no initial cooling. The quality factors impacting marketability of fresh oak mushrooms were color change and appearance of decay. Off-odor did not occur or developed only slightly, so it did not affect oak mushroom quality within 6 weeks of low temperature storage. In all treatment groups, the shelf life in which 100% marketability was maintained was up to 3 weeks. At week 5, percent marketability of the 3 treatment groups 1 hour room cooling treatment at 0°C, 1 hour forced air cooling, and control was 100%. 80% In the group that underwent 30 min forced air cooling retained 80% marketability, and the group exposed to 1 day in room cooling at -3oC retained 86.7% marketability. At week 6 of 1oC storage, the marketability ratio was 80% in the 1 day room cooling at 0oC group, 66.7% in the 1 day room cooling at 3oC group, 46.7% in the 1 hour forced air cooling group, and 33% or less in all other treatment groups. Therefore, the most suitable initial cooling parameter to extend shelf-life of oak mushrooms is 1 day of in room cooling at 0oC immediately after harvest.

This paper examined the dynamic instability of a shallow arch according to the response characteristics when nearing critical loads. The frequency changing feathers of the time-domain increasing the loads are analyzed using Fast Fourier Transformation (FFT), while the response signal around the critical loads are analyzed using Hilbert-Huang Transformation (HHT). This study reveals that the models with an arch shape of h = 3 or higher exhibit buckling, which is very sensitive to the asymmetric initial conditions. Also, the critical buckling load increases as the shape increases, with its feather varying depending on the asymmetric initial conditions. Decomposition results show the decrease in predominant frequency before the threshold as the load increases, and the predominant period doubles at the critical level. In the vicinity of the critical level, sections rapidly manifest the displacement increase, with the changes in Instantaneous Frequency (IF) and Instant Energy (IE) becoming apparent.

전지구 해양 해빙 예측시스템인 NEMO-CICE/NEMOVAR의 해빙 초기조건의 특성을 2013년 6월부터 2014년 5월까지 북극영역에 대하여 분석하였다. 이를 위하여 관측 자료와 재분석 자료를 모델의 초기조건과 비교하였다. 모델 초기조건은 관측에서 나타나는 해빙 면적과 해빙 두께의 월 변동을 잘 보이는 반면, 분석 기간 동안 관측과 재분석 자료보다 북극의 해빙 면적을 좁게, 해빙 두께를 얇게 나타내었다. 모델 초기조건의 북극 해빙 면적이 좁은 것은 해빙의 경계 지역에서 해빙 농도 초기조건이 약 20% 정도 재분석자료보다 낮기 때문이다. 또한 북극 평균 해빙 두께가 얇게 나타나는 이유는 연중 두꺼운 해빙이 유지되는 그린란드 및 북극 군도와 인접한 북극해 영역에서 모델의 초기조건이 약 60 cm 정도 얇기 때문이다.

We construct several Milky Way-like galaxy models containing a gas halo (as well as gaseous and stellar disks, a dark matter halo, and a stellar bulge) following either an isothermal or an NFW density profile with varying mass and initial spin. In addition, galactic winds associated with star formation are tested in some of the simulations. We evolve these isolated galaxy models using the GADGET-3 N-body/hydrodynamic simulation code, paying particular attention to the effects of the gaseous halo on the evolution. We find that the evolution of the models is strongly affected by the adopted gas halo component, particularly in the gas dissipation and the star formation activity in the disk. The model without a gas halo shows an increasing star formation rate (SFR) at the beginning of the simulation for some hundreds of millions of years and then a continuously decreasing rate to the end of the run at 3 Gyr. Whereas the SFRs in the models with a gas halo, depending on the density profile and the total mass of the gas halo, emerge to be either relatively flat throughout the simulations or increasing until the middle of the run (over a gigayear) and then decreasing to the end. The models with the more centrally concentrated NFW gas halo show overall higher SFRs than those with the isothermal gas halo of the equal mass. The gas accretion from the halo onto the disk also occurs more in the models with the NFW gas halo, however, this is shown to take place mostly in the inner part of the disk and not to contribute significantly to the star formation unless the gas halo has very high density at the central part. The rotation of a gas halo is found to make SFR lower in the model. The SFRs in the runs including galactic winds are found to be lower than those in the same runs but without winds. We conclude that the effects of a hot gaseous halo on the evolution of galaxies are generally too significant to be simply ignored. We also expect that more hydrodynamical processes in galaxies could be understood through numerical simulations employing both gas disk and gas halo components.

We employed two data assimilation techniques including MM5 Four Dimensional Data Asssimilation (FDDA) and Local Analysis and Prediction System (LAPS) to find out the effects of the changed initial conditions on the wind fields simulation according to the objective analysis methods. We designed 5 different modeling cases. EXP B used no data assimilation system. Both EXP F1 using surface observations and EXP F2 with surface and upper-air observations employed MM5 FDDA. EXP L1 using surface observations and EXP L2 with surface and upper-air observations used LAPS. As results of, simulated wind fields using MM5 FDDA showed locally characterized wind features due to objective analysis techniques in FDDA which is forcefully interpolating simulated results into observations. EXP F1 represented a large difference in comparison of wind speed with EXP B. In case of LAPS, simulated horizontal distribution of wind fields showed a good agreement with the patterns of initial condition and EXP L1 showed comparably lesser effects of data assimilation of surface observations than EXP F1. When upper-air observations are applied to the simulations, while MM5 FDDA could hardly have important effects on the wind fields simulation and showed little differences with simulations with merely surface observations (EXP F1), LAPS played a key role in simulating wind fields accurately and it could contribute to alleviate the overestimated winds in EXP L1 simulations.