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## Aims and Scope

The origin of New Physics: Sae Mulli (NPSM, ISO abbreviation: New Phys.: Sae Mulli.): Sae Mulli (새물리 in Korean characters means ‘new physics’) is the oldest Korean pure scientific journal. It was first published in 1961 just after the Korean War by the Korean Physical Society (KPS). The primary mission of Sae Mulli was to start building up Korean physics research community from almost nothing and in fact Sae Mulli had made tremendous contributions to the Korean science community. Through a peer-review system, Sae Mulli had continued elevating the level of scientific researches, consequently becoming a cornerstone of the economic miracle of Korea...

Editor-in-Chief : Guinyun KIM
New Physics: Sae Mulli Editorial Board

• pISSN : 0374-4914
• eISSN : 2289-0041
Research Papers
Negative Refraction of Ultrasound in a Two-Dimensional Prism-Shaped Phononic Crystal
Yoon Mi KIM1, Kang Il LEE*1, Hwi Suk KANG2, Suk Wang YOON2
1 Department of Physics, Kangwon National University, Chuncheon 24341, Korea
2 Department of Physics, Sungkyunkwan University, Suwon 16419, Korea
 The present study aims to investigate theoretically and experimentally the negative refraction of ultrasound in a two-dimensional prism-shaped phononic crystal with a square lattice in water. Using the finite element method, we calculated the acoustic band structure along the $\Gamma$X direction of the first Brillouin zone of a two-dimensional phononic crystal consisting of periodic square arrays of stainless-steel solid cylinders with radii of 0.5 mm and with a lattice constant of 1.5 mm in water. Based on the calculated band structure, the pressure fields of ultrasound transmitted through the phononic crystal in water were calculated over a wide frequency range from 0.5 to 1.0 MHz by using the finite element method, and they were measured experimentally to validate the predicted results. The positive and the negative angles of refraction obtained by using both the finite element method and the refraction experiment were in good agreement with those calculated by using Snell’s law. New Physics: Sae Mulli 2016; 66: 930-935
Analysis of the Steady-State Orbit in the Free-Electron Laser Based on a Two-Frequency Wiggler
Ki-Bum KIM*
Institute of Liberal Education, Kangwon National University, Chunchon 24341, Korea
 In the free-electron laser, the stability of the electron orbit plays an important role in obtaining high-power radiation, and the two-frequency wiggler is known as one method to improve the stability of the electron orbit. In this paper, we study the stability of relativistic electron orbits in a realizable, helical, wiggler magnetic field based on the two-frequency wiggler including the self-generated field. The solutions for the steady-state orbits are numerically calculated from the Hamiltonian which is canonically transformed by using a generating function. To investigate the regular and the chaotic states of off-axis electron orbits, we use a numerical method to analyze the Poincar$\grave{e}$ maps, the spectrum of electron orbits, and the maximal Lyapunov exponent.  New Physics: Sae Mulli 2016; 66: 916-922
New Physics: Sae Mulli 2016; 66: 941~1061