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김홍,이부영,이준호,김영철,Kim H,Lee B. Y,Lee J. H,Kim Y. C 한국초전도학회 2004 Progress in superconductivity Vol.6 No.1
The policrystalline$SmBa_2$$Cu_2$$O_{y}$ was synthesized by the solid state reaction method. The dependence of AC susceptibility on temperature and applied ac field was studied. The critical temperature $T_{c}$ is about 92 K. As the ac field is increased, the slope and the value of real part of susceptibility become smaller and the peak position of imaginary part $T_{P}$ was shifted to a lower temperature with peak broadening. Using Bean's model, we determined intergrain critical current density $J_{c}$ and obtained $44 A/{cm}^2$ at 75 K. From the relation of the $J_{c}$ (T)=($1-T/T_{c}$ )$^{\beta}$ we obtained $\beta$=0.8 and found that the Josephson junction type of the $SmBa_2$$Cu_2$$O_{y}$ is SIS junction. The peak of the imaginary part shifts to higher temperature with increasing frequency, f. from Arrhenius plot, we obtained the activation energy of about 0.96 eV.
K.H. Park,김홍인,D. Mishra,C.W. Nam,J.T. Park,D.J. Kim,P.K. Parhi 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.6
Baking–leaching-solvent extraction process was investigated to recover metal values from waste petroleum catalyst. Baking of Mo–Ni/Al2O3 spent catalyst with H2SO4 followed by leaching of the baking mass concentrate was presented. Under optimum baking condition (temp. 300 8C, H2SO4 = 1.2stoichiometric, baking time 1 h), and low acid leaching condition (temp. 95 8C, H2SO4 = 2% (v/v), pulp density 5% and leaching duration 30 min), about 96% Mo, 99% Al and 95% Ni was dissolved. Baking–leaching results were interpreted by two different statistical analysis approaches namely Principal Component (PCA) and Multi Linear Regression Analysis (MLRA). The generated leach liquor was further subjected to the solvent extraction of Mo(VI) by LIX 84-I followed by aluminum using Na-Cyanex 272. A quantitative extraction of Mo(VI) and Al was achieved in 2-stage at A:O ratio of 1:1 with 40% LIX-84-I and 2-stages at 1:1 phase ratio with 60% neutralized Cyanex 272, respectively. While stripping the metals from loaded organic such as Mo(VI) using 20% NH4OH and Al with 3 M H2SO4, the metal concentration in the strip solution were enriched up to 1.5 times and 3 times in two and three number of stages, respectively. Based on the results of present study, a conceptual process flow diagram was proposed.
광통신용 1.3 ㎛ Ridge Waveguide Distributed Feedback Laser Diode의 제작과 특성 평가
박경현(K. H. Park),이중기(J. K. Lee),장동훈(D. H. Jang),유지범(J. B. Yoo),강승구(S. K. Kang),김홍만(H. M. Kim),이용탁(Y. T. Lee),박형무(H. M. Park),조호성(H. S. Cho),홍창희(T. Hong) 한국광학회 1994 한국광학회지 Vol.5 No.1
발진파장이 1.3 ㎛인 Ridge Waveguide Distributed Feedback Laser Diode(RWG-DFB-LD)를 제작하고 특성을 평가하였다. 회절격자 형성은 광간섭무늬 노광법을 이용하였고 결정성장은 LPE로 수행하였다. 제작된 RWG-DFB-LD의 발진 임계전류는 67 ㎃이었고, 1296.5 ㎚ 파장에서 측모우드 억제율 30 dB 이상으로 단일 종모우드로 발진하였다. 금지대역폭 측정에 의한 회절격자 결합계수(k)는 40 ㎝-¹로 평가되었다. 소신호 변조특성평가 결과 제작한 RWG-DFB-LD는 1.2 Ith에서 1.99 ㎓의 변조대역폭(f_(-3dB)) 특성을 보였다. We fabricated and characterized RWG-DFB-LDs emitting at 1.3 ㎛ wavelength. For fabrication of the laser diode, inteference fringe of optical beams was used for grating formation and epi layers were grown by LPE. The fablicated RWG-DFB-LD operated in a single longitudinal mode with more than 30 dB SMSR at 1296.5 ㎚ emitting wavelength and its threshold current was 67 ㎃. Coupling coefficient (k) was estimated as 40 ㎝-¹ by means of stop-band measurement. Finally, we show that the RWG-DFB-LD fabricated in this experiment can be applicable as light source of 2.5 Gbps optical communication system from the fact that the small signal response of the RWG-DFB-LD rated up to 1.99 ㎓ at pre-bias level of 1.2Ith.
광통신용 1.55 ㎛ PBH - DFB - LD 스펙트럼 특성
장동훈(D. H. Jang),이중기(J. K. Lee),이승원(S. W. Lee),박경현(K. H. Park),김정수(J. S. Kim),김홍만(H. M. Kim),황인덕(I. D. Hwang),박형무(H. M. Park),조호성(H. S. Cho),홍창희(T. Hong) 한국광학회 1994 한국광학회지 Vol.5 No.1
LPE와 간섭노광법을 이용하여 1.55 ㎛ 파장의 InGaAsP/InP PBH-DFB-LD를 제작하고 스펙트럼 특성을 평가하였다. 제작된 PBH-DFB-LD의 발진 임계전류는 15 ㎃ 이하이며, 1.55 ㎛ 파장에서 광출력 7 ㎽ 이상까지도 단일 종모우드로 동작하였으며 측모우드 억제율 35dB 이상을 얻었다. 본 연구에서 제작된 PBH-DFB-LD 발진파장의 온도 의존 특성은 0.9Å/℃이며, 금지대역폭 측정에 의한 회절격자의 결합계수(k)는 97 ㎝-¹로 평가되었다. PBH-DFB-LD emitting at 1.55 ㎛ wavelength has been fabricated for 2.5 Gbps optical fiber communications. For fabrication of PBH-DFB-LD, inteference expose for grating formation and 3-step LPE epitaxial growth was used. Fabricated PBH-DFB-LD operates in single longitudinal mode with more than 35dB SMSR and its threshold current is less than 15 ㎃. The operating wavelength is 1530~1550 ㎚ with the temperature dependence of 0.9Å/℃. Coupling coefficient(k) was estimated as 97 ㎝-¹ by means of stop-band measurement. PBH-DFB-LD fabricated in this experiment can be applicable as light source for 2.5 Gbps optical fiber communication system.
2.5 Gbps 광통신용 Distributed Feedback Laser Diode(DFB - LD) 모듈 제작 및 광송신 실험
박경현(K. H. Park),강승구(S. G. Kang),송민규(M. K. Song),이중기(J. K. Lee),조호성(H. S. Cho),장동훈(D. H. Jang),박찬용(C. Y. Park),김정수(J. S. Kim),김홍만(H. M. Kim),박형무(H. M. Park),한정희(J. H. Han),심창섭(C. S. Shim) 한국광학회 1994 한국광학회지 Vol.5 No.3
DFB-LD 칩으로부터 단일모드 광섬유 부착 2.5 Gbps 광통신용 광원인 DFB-LD 모듈을 설계, 제작하였다. DFB-LD 모듈은 광 isolator가 삽입된 2 렌즈 quasi confocal 광학계로 구성된 원통형 서브 모듈과 14 pin butterfly 패키지가 분리된 구성으로서 이들 사이의 전기적 연결은 bias-T 회로가 형성된 하이브리드 기판으로 이루어지도록 설계하였다. 모듈 제작시 정밀한 부품 고정이 요구되는 서브 모듈 조립에는 레이저 웰딩 방법을 사용하였다. 제작된 DFB-LD 모듈은 광결합 효율 20%, -3dB 소신호 변조 대역폭 2.6 ㎓ 이상의 특성을 가졌으며, 온도 순환검사에도 10% 이내의 광출력 변동만을 보임으로써 기계적 신뢰성을 확인할 수 있었다. 제작된 DFB-LD 모듈의 광송신 성능을 실제 2.5 Gbps 광통신 시스템의 광원으로 적용하여 평가한 결과 47 ㎞의 광섬유 전송시 BER 1×10^(-10) 조건에서 최대 -30.2 dBm의 수신감도를 얻었으며, 이 때 전송페널티는 소광비에 의한 것이 1.5 dB, 분산에 의한 것이 1.0 dB로 나타났다. We designed and fabricated the single mode fiber pigtailed DFB-LD module for 2.5 Gbps optical communication system. In the design of the DFB-LD module, we made the module divided into two parts of inner sub-module and outer 14-pin butterfly package and cylindrical shaped sub-module contain quasi confocal 2 lens system including optical isolator and electrical connection between these parts via hybrid substrate of bias T circuit.<br/> Laser welding was used to assemble the sub-module which requires accurate fixing between optical elements. The fabricated DFB-LD module showed optical coupling efficiency of 20% and -3 dB small signal response of more than 2.6 ㎓. We confirmed mechanical reliability of the module by temperature cycle test where the tested module exhibit optical power fluctuation of less than 10%. Finally we evaluated the performance of the fabricated DFB-LD module as light source of 2.5 Gbps optical communication system, sensitivity of -30.2 dBm was obtained through 47 ㎞ optical fiber transmission under the criterion of 1×10^(-10) BER and transmission penalties were 1.5 dB caused by extinction ratio and 1.0 dB caused by chromatic dispersion of normal single mode fiber.