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전관수,윤화중 충남대학교 자연과학연구소 1984 忠南科學硏究誌 Vol.11 No.2
In order to investigate the human hearing sensitivities of sound the sound loudness levels for the white-noise were measured, and the results were compared with that of the pure-tone which was investigated by Fletcher and Munson. The results show that the human hearing sensitivity is higher in the lower frequency range of noise than pure-tone, on the contrary that is lower in the high frequency range of noise than pure-tone. Also the saturation phenomena of both of the white-noise and pure-tone were investigated. As a result we were able to confirm that the saturation phenomena for the white-noise were occured in 10 ㏈ higher sound intensity level for the same frequency range that of the pure-tone.
윤화중,전관수 忠南大學校 環境問題硏究所 1988 環境硏究 Vol.6 No.1
The environmental noise measurements were carried out in Chungnam National University(CNU) campus including interior of CNU library, and educational influences caused by the noises were investigated and evaluated in this study. According to the results of noise measurements at the several places the noise level was indicated 58 dB minimum value and 65dB maximum value. Both of these value shows higher-value as compared with environmental standard value of 50dB.
윤화중,홍은숙,전관수 충남대학교 자연과학연구소 1989 忠南科學硏究誌 Vol.16 No.2
In order to investigate the acoustical attenuation effects from simple expansion chamber type muffler the following experiments were carried out ; the spectrum analyzer which has 25Hz analyzing frequency intervals was devised. The changing of acoustical attenuation frequency intervals was devised. The changing of acoustical attenuation effects were observed by varying the diameter and the length of the muffler. The diffuser was attached to the muffler in order to decrease the sound pressure levels more and then the acoustical attenuation effects were investigated. The phenomena on the sound wave surface was curvatured and visualized by the diffuser was confirmed in photographic developing of the attenuation wave.
Fe-Ni에 Si와 Cr을 첨가한 박막의 자기적 특성에 관한 연구
금채,이명섭,전관수 충남대학교 자연과학연구소 1989 忠南科學硏究誌 Vol.16 No.1
Alloy thinfilms-Fe_50 Ni_59, Fe_47.5Ni47.5 Si47.5, Fe_47.5Ni_47.5 Cr_47.5- have been made by DC sputtering method. The electric and magnetic properties of alloy thinfilms have been measured between 100K and 300K. The temperature coefficients of resistivity of Fe_50Ni_50 was 0.7053 10^-6/K, that of Fe_47.5 Ni_47.5 Si_47.5 was 0.693 10^-6/K, that of Fe_47.5Ni_47.5 Cr_47.5 was 1.8363 10^-6/K. The magnetic properties of Fe-Ni compound containing Si have been better and Fe-Ni compounds containing Cr have had low electric resistance and high coercivity.
OUTER AUTOMORPHISM GROUPS OF CERTAIN POLYGONAL PRODUCTS OF GROUPS
Kim, Goan-Su Korean Mathematical Society 2008 대한수학회보 Vol.45 No.1
We show that certain polygonal products of any four groups, amalgamating central subgroups with trivial intersections, have Property E. Using this result, we derive that outer automorphism groups of polygonal products of four polycyclic-by-finite groups, amalgamating central subgroups with trivial intersections, are residually finite.
OUTER AUTOMORPHISM GROUPS OF POLYGONAL PRODUCTS OF CERTAIN CONJUGACY SEPARABLE GROUPS
Kim, Goan-Su,Tang, Chi Yu Korean Mathematical Society 2008 대한수학회지 Vol.45 No.6
Grossman [7] showed that certain cyclically pinched 1-relator groups have residually finite outer automorphism groups. In this paper we prove that tree products of finitely generated free groups amalgamating maximal cyclic subgroups have residually finite outer automorphism groups. We also prove that polygonal products of finitely generated central subgroup separable groups amalgamating trivial intersecting central subgroups have residually finite outer automorphism groups.
CONJUGACY SEPARABILITY OF CERTAIN FREE PRODUCT AMALGAMATING RETRACTS
Kim, Goan-Su Korean Mathematical Society 2000 대한수학회보 Vol.37 No.4
We find some conditions to derive the conjugacy separability of the free product of conjugacy separable split extensions amalgamated along cyclic retracts. These conditions hold for any double coset separable groups and free-by-cyclic groups with nontrivial center. It was known that free-by-finite, polycyclic-by-finite, and fuchsian groups are double coset separable. Hence free products of those groups amalgamated along cyclic retracts are conjugacy separable.
THE KNOT $5_2$ AND CYCLICALLY PRESENTED GROUPS
Kim, Goan-Su,Kim, Yang-Kok,Vesnin, Andrei Korean Mathematical Society 1998 대한수학회지 Vol.35 No.4
The cyclically presented groups which arise as fundamental groups of cyclic branched coverings of the knot $5_2$ are studied. The fundamental polyhedra for these groups are described. Moreover the cyclic covering manifolds are obtained in terms of Dehn surgery and as two-fold branched coverings of the 3-sphere.
SEPARABILITY PROPERTIES OF CERTAIN POLYGONAL PRODUCTS OF GROUPS
Kim, Goan-Su,Tang, C.Y. Korean Mathematical Society 2002 대한수학회지 Vol.39 No.3
Let G = E${\ast}_{A}F$, where A is a finitely generated abelian subgroup. We prove a criterion for G to be {A}-double coset separable. Applying this result, we show that polygonal products of central subgroup separable groups, amalgamating trivial intersecting central subgroups, are double coset separable relative to certain central subgroups of their vertex groups. Finally we show that such polygonal products are conjugacy separable. It follows that polygonal products of polycyclic-by-finite groups, amalgamating trivial intersecting central subgroups, are conjugacy separable.
CONJUGACY SEPARABILITY OF FREE PRODUCTS WITH AMALGAMATION
Kim, Goan-Su Korean Mathematical Society 1997 대한수학회논문집 Vol.12 No.3
We first prove a criterion for the conjugacy separability of free products with amalgamation where the amalgamated subgroup is not necessarily cyclic. Applying this result, we show that free products of finite number of polycyclic-by-finite groups with central amalgamation are conjugacy separable. We also show that polygonal products of polycyclic-by-finite groups, amalgamating central cyclic subgroups with trivial intersections, are conjugacy separable.