Eγ=30MeV 이하에서의 ⁴He의 광핵분열 반응에 대한 이론적인 연구

김경훈,유평열 順天大學校 1994 論文集 Vol.13 No.1

□ ⁴He(Υ,p)³H and ⁴He(Υ,n)³He cross sections have been caculated for photonenergies from the (Υ,n)threshold to 30 MeV. Effects of Coulomb ineractions, nuclear Potential shape and mass differences have been taken into account using a shell-model caculation of p-³H and n-³He elastic scattering. The ratio σ(Υ,p)/σ(Υ,n)is predicted to be close to 1, expect at energies very close to the (Υ,n) threshold.

Asymmetric Magnetization Reversal of the Soft layer in the Pt/Co bilayer with Perpendicular magnetic anisotropy

Pyeong-Yeol Yu,Myeonghwan Kang,Hye-Jin Ok,Gang Hwi Kim,Suyeong Jeong,Younggun Park,Ki-Suk Lee 한국자기학회 2022 한국자기학회 학술연구발표회 논문개요집 Vol.32 No.2

Spin-Orbit Coupling and Crystal Field Effect of Platelet and Bulk Type Cadmium Sulfide Semiconductor

Yu,Pyeong Yeol 順天大學校 1990 論文集 Vol.9 No.1

2단 수직 전기로(고온부;1165℃,저온부:1150℃)에 의한 승화 방법으로 판상형과 벌크형의 황화카드뮴 반도체 단결정을 성장하였다.Laune Pattern 결과 이들의 구조는 육방정계이었고 판상형 단결정은 {1120} 평면이 나타나며 벌크형 단결정은 ample 길이를 따라 C축 방향으로 성장하였다. Van-der Pauw 방법에 의한 Hall effect 측정결과 열처리하기 전 단결정의 전하밀도와 운동도는 각각 6.84x10??m??,2.8x10??m??/V-sec이었고 벌크형은 1.37x10??m??, 2.07x10??m??/V-secdldjTek. 또 공기중에서 열처리한 후 판상형과 벌크형의 carrier density는 각각 1.9x10??m??,2.5x10??m??이었다. 반사율 측정과 광전도도 스펙트럼의 엑시톤 피크 분석의 경우 H??과H??는 4.2K인 낮은 온도에서 나타나는 것으로 보고되었으나, 공기중에서 sample을 열처리한 경우에는 광전류 피크의 분석결과 상온 293K에서 33K까지의 높은 온도영역에서도 H??과H??가 나타나는 것을 알아냈다. 결정장 상호작용의 splitting 에너지차 H??과 스핀 - 궤도 coupling 에너지차 H??는 각각 0.027eV,0.063eV이었다. Platelet and bulk type single crystals of CdS are grown using sublimation method with a two step vertical furnace(H.T.1165 ℃ and L.T.1150 ℃ ). Laue photographs of these crystals show their structure being hexagonal with the {1120} plane for platelet samples of average size 15x10x0.02mm and with the c axis along ampoule length for bulk samples. Carrier density and mobility of the platelet and bulk type samples before annealing has the value of 6.84x10??m?, 2.80x10??m?? /V-sec and 1.37x10??m??, 2.07x10??m??/V-sec at room temparature from the measurement of Hall effect by Vander Pauw method, respectively. But after annealing the carrier density of the platelet and bulk type samples become the value of 1.90x10??m?? and 2.50x10??m?? at room temperature, respectivelty. Hcr and Hso appeared at the low temparature of 4.2K in the exciton peaks analysis of reflection and photoconductivity spectra, but after annealing in air atmosphere environment, Hcr and Hso appeared in the range of 293K to33K in the analysis of energy difference of photocurrent peaks. The splitting of crystal field interaction Hcr and spin-orbit coupling Hso have the values of 0.027eVand 0.063eV,respectively.

Direct Observation of Multi-level Switching behavior in the Multi-layered ferromagnetic thin film

Pyeong-Yeol Yu,Myeonghwan Kang,Sooseok Lee,Dae-Han Jung,Hye-Jin Ok,Gang Hwi Kim,Suyeong Jeong,Younggun Park,Ki-Suk Lee 한국자기학회 2022 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2

Si-doping effects on grain growth and magnetic properties in LaCaCo-substituted M-type hexaferrites

Pyeong-Yeol Yu,Kyoung-Seok Moon,Young-Min Kang 한국자기학회 2020 한국자기학회 학술연구발표회 논문개요집 Vol.30 No.1

육방정 페라이트 복합상의 합성 및 GHz 대역 전자기파 흡수 특성

유평열(Pyeong-Yeol Yu),강영민(Young-Min Kang) 한국자기학회 2020 韓國磁氣學會誌 Vol.30 No.4

Multi-hexaferrites (Sr<SUB>3-x</SUB>Ca<SUB>x</SUB>Co₂Fe<SUB>24</SUB>O<SUB>41</SUB>, x = 0, 0.1, 0.2, 0.3, 0.4) with more than two types of hexaferrite phases were synthesized by solid-state reactions and substitution of Sr by Ca in the stoichiometric Z-type Sr₃Co₂ hexaferrite composition. Multi-hexaferrites consisting of Z + U + W, X + U +W, and X + W phases were formed for the samples with x = 0, x = 0.1, and x≥0.2, respectively, upon first and second calcinations at 1160 and 1210 oC. The saturation magnetization increased largely with Ca-doping (x≥0.1). The complex permeability spectra were shifted to higher frequency and the imaginary permeability peak became broader by Ca doping. In the RL maps plotted as functions of sample thickness (d) and frequency (f), the strong EM absorbing area moved to higher f and lower d direction with increasing of x. For the Ca-doped samples (x≥0.1), the minimum reflection loss (RL < -30 dB) corresponding to the maximum microwave absorption was obtained at f = 10 GHz vicinity and d = ~2 ㎜, while the undoped sample exhibited the minimum RL (-42 dB) at f = 4.6 GHz and d = 4.6 ㎜. The highest EM wave absorption performance of RL = 56.5 dB could be achieved at the sample of x = 0.3 with d = 2.2 ㎜ and f = 11.4 GHz. For the x = 0.2 samples, RL <-10 dB (EM energy absorption above 90%) is satisfied in the full X-band frequency range (8~12 GHz) with d = 2.3 ㎜. The broad-band EM absorption properties could be achieved owing to the overlaps of the hard-soft magnetic properties of the multi-hexaferrites.

Cu_2S/CdS 태양전지 제작과 그 특성 연구

유평렬 순천대학교 기초과학연구소 1990 基礎科學硏究誌 Vol.1 No.-

The single crystal of cadmium sulfide was grown by vertical sublimation method. The lattice constants of CdS single crystal by extrapolation method are a_0=4.1387Å and c_0=6.7188Å respectively. The Cu_2S/CdS solar cell was fabricated using the single crystal of cadmium sulfide and the CuCl solution. After annealing for 2 minutes at 250℃ in air atmosphere, the Light-to-Dark JV cross over effect of the Cu_2S/CdS solar cell was measured. The values of Voc, Jsc, Vop, Jop, FF, and efficiency are 0.38volt, 4㎃/㎠, 0.30volt. 3.7㎃/㎠, 0.73, and 3.7%, respectively. The spectral response of the solar cell show the peaks at 498㎚(2.49eV) and 585㎚(2.12eV).

lodine을 촉매로한 기상성장 방법에 의한 CdS 단결정 성장 및 Hall Effect 특성

유평렬,신영진,정태수 順天大學校 1988 論文集 Vol.7 No.1

Crystal growth of cadmium sulfide by the halogen transport method was carried out using iodine as a transporting agent in a sealed ampoule kept at temperatures of 700℃ and 900℃ for the growth part and the source part, respectively. The lattice constants of the grown CdS(PL A, B) single crystal were measured to the a??=4.1380 Å and c??=6.7178 Å,while CdS(PC C, D) single crystal were measured to the a??=4.1377 Å and c??=6.7207 Å, The electron carrier concentrations and Hall mobility were also measured using the van der pauw method at the temperature of 293k and below, and their values are about ∼10²³m-³ and about 10-²∼10-³m²/v·s, respectively.

Vapour phase transport 방법에 의한 CdS 단결정 성장 및 광전류와 광발광 특성

유평렬 順天大學校 1988 論文集 Vol.7 No.1

Crystal growth of cadmium sulfide by the halogen transport method was carried out using iodine as a transporting agent in a sealed ampoule kept at temperatures of 700℃ and 900℃ for the growth part and the source part, respectively. The lattice constants of the grown CdS(PL A, B) single crystal were measured to the a??=4.1380 Å and c??=6.7178 Å,while CdS(PC C, D) single crystal were measured to thd a??=4.1377 Å and c??=6.7207 Å. Photoluminescence emission spectra of the grown samples show a prominent G?? line peak, whereas its photocurrent spectra show a peak at 512nm {CdS(PLA)}, 502.5nm {CdS(PL B)}, 500nm {CdS(PC C)}, and 590nm {CdS(PC D)} due to an intrinsic transition peaks at 760nm(1.63 ev) and 1580nm (0.79 ev) by the infrared quenching effect.

Cds 광전도쎌의 Maximum Allowable Power Dissipation 및 Photoconductivity Gain

유평렬 順天大學校 1991 論文集 Vol.10 No.1

황화카드뮴 단결정을 성장하여 광전도쎌로서의 응용성을 알아보기 위해 최대 허용 전력소비와 광전도도 이득에 대해 연구하였다. 300Lux, 500Lux, 800Lux의 조도에서의 실험을 통하여 구한 각 시료의 최대 허용 전력소비의 연구 결과 공기중에서 열처리한 광전도쎌의 MAPD값이 295mW로 가장 좋은 특성을 보였다. 또한 photo-Hall 효과 측정 및 반응시간의 측정으로 광전도 이득 값을 계산한 결과 진공중에서 열처리한 광전도쎌의 이득이 18.8로 광감도가 가장 우수하였다. Crystal growth of cadmium sulfide by the subimation method was carried out using two-zone vertical electric furnace. The CdS:air, CdS:vacuum, CdS:Cd photoconductive cell was fabricated, and then its characteristics of maximum allowable power dissipation and photoconductivity gain were investigated by photo-Hall effect, response time, and illumination current-voltage measurements etc. The values of MAPDair, MAPDvac, and MAPDcd were 295mW, 126mW, and 8.6mW, respectively. The values of the photoconductivity gain Gair, Gvac, and Gcd were 13.5, 18.8, and 9.3, respectively.