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김동철,유건호 慶熙大學校 레이저 工學硏究所 1997 레이저공학 Vol.8 No.-
Use of one-band model in the calculation of gain of semiconductor lasers is convenient because it is easy to understand and takes less time to implement. However, it gives an error in the gain by neglecting the nonparabolicity. In this paper, we study the limit of the one-band model by comparing the gain calculated by the one-band model with that by a multiband model. We find that, if the active layer is bulk, the peak gain by the one-band model is approximately same as that by a multiband model. However, if the active layer is a quantum well, the peak gain by the one-band model is much larger, and the one-band model may not be used for a quantitative analysis.
Characteristics of Silver Ion - Exchanged Glass Waveguides at 633 ㎚ and 1.5㎛
유건호(Keon-Ho Yoo) 한국광학회 1992 한국광학회지 Vol.3 No.3
은 이온 교환법으로 만든 유리 도파로는 표면 굴절율 차가 크고 도파로 깊이가 얕기 때문에, 반도체 박막 이식법을 이용한 반도체 소자와 유리 도파로의 혼성 집적에 사용되기에 적합하다. 이 논문은 묽게한 질산화은 용액에서 이온 교환으로 만들어진 평면 및 채널 유리 도파로의 가시광선 및 적외선 파장 영역에서의 특성을 보고한다. 특히, 광통신에 중요한 파장인 1.5㎛에서의 단일 모우드 채널 도파로의 제작 조건을 결정하였다. 또한 여러가지 다른 구성 형태의 방향성 결합기가 제작되어, 파장과 편광 방향에 따른 3 ㏈ 결합 길이가 결정되었다. Silver ion-exchanged glass waveguide with its large surface index difference and shallow depth is suitable to be used for the hybrid integration of semiconductor device and glass waveguide using the semiconductor film grafting technique. We report characteristics of the planar and channel glass waveguides exchanged in the diluted silver nitrate melt in the visible and infrared spectral region. Especially, we determined the fabrication parameters for single-mode channel waveguide at 1.5 ㎛, an important wavelength in the optical communication. Directional couplers with several different configurations were fabricated, and their 3 ㏈ coupling length was determined as a function of wavelength and polarization.
Design of a High-efficiency Fiber-to-chip Coupler with Reflectors
Keon Yoo,Jong-Ho Lee 대한전자공학회 2016 IEIE Transactions on Smart Processing & Computing Vol.5 No.2
In this paper, an inversely tapered coupler with Bragg reflectors is reported for the first time. With appropriately positioned reflecting structures, our fiber-to-chip coupler can more efficiently transmit the light from fiber to a waveguide in a photonic integrated circuit (PIC). A numerical simulation evaluated the coupler’s efficiency with the reflector. Optimized parameters that maximize the efficiency of the coupler are also investigated. Simulation results show that the reflector with appropriate parameters enhances efficiency by up to 7 dB. Likewise, Bragg metal reflectors implemented by the conventional metallization process can also improve efficiency. It is also shown that the proposed reflector enhances the coupling efficiency in a double-tip taper coupler.
유전성 대사질환에서의 동종조혈모세포이식 : 단일 기관에서의 경험 A single center experience
유건희,김흥렬,이지은,이호영,천정미,성기웅,구홍회,이문향,진동규,김종원,김대원,김형록 대한조혈모세포이식학회 2001 대한조혈모세포이식학회지 Vol.6 No.2
배경: 유전성 대사질환의 치료로서 효소 요법 및 유전자 치료가 제한적인 현실에서 동종 조혈모세포이식이 현재로선 가장 중요한 치료가 될 수 있다. 본 연구에서는 단일 기관에서 유전성 대사질환에 대해 동종 조혈모세포이식을 시행한 경험을 보고하고자 하였다. 방법: 삼성서울병원 유전성 대사질환 조혈모세포이식팀에서는 1999년 12월부터 2001년 3월까지 총 6례의 유전성 대사질환을 대상으로 동종 조혈모세포이식을 시행하였다. 대상 질환은 Hunter 증후군 3례, galactosialidosis 1례, 이염성 백질이영양증 1례, 부신백질이영양증 1례였으며 성별 분포는 남아가 5명, 여아가 1명이었으며 연령 분포는 2년 9개월에서 15년 9개월이었다. 5례는 HLA 일치 혈연간 골수이식이었으며 1례는 HLA 불일치 T 림프구 제거 말초혈액 조혈모세포이식이었다. 전처치는 모두 BuCy를 사용하였으며 이식편대숙주반응의 예방에는 cyclosporine을 사용하였다. 이식된 세포는 유핵세포가 4.81×10^(8)(2.40~7.01×10^(8))/kg이었으며 CD34+ 세포는 3.65×10^(6)(0.88~10.72×10^(6))/kg이었다. 결과: 이식 후 조혈기능의 회복은 모두 조기에 달성되었으며(ANC>500: 정중 9.5일, 범위 9~14일; PLT>50K: 정중 32일, 범위 23~34일) 이식과 관련된 합병증은 Gr I의 aGVHD 3례, 국한성의 cGVHD 1례, 경증의 간정맥 폐쇄성 질환이 1례이었다. 모든 환자에서 직간접적으로 이식 후 효소의 생산이 증가함이 확인되었으며 임상적인 호전을 보인 경우가 4례, 질병 진행이 중단된 경우가 1례, 질병이 진행된 경우가 1례이었다. 질병 진행이 중단되었던 1례는 면역억제제 투여 중 수두 감염에 의한 폐출혈로 사망하였다. 결론: 유전성 대사질환에서 동종 조혈모세포이식이 가장 중요한 치료법으로 사용될 수 있고 중추신경계 증상이 나타나기 전, 가능한 조기에 조혈모세포이식을 시행하는 것이 바람직할 것이며 적극적인 지지 요법이 필요하다. 향후 더 많은 임상 경험이 필요하리라 사료된다. Background: Allogeneic hematopoietic stem cell transplantation (HSCT) may be the most important treatment modality to cure a number of genetic metabolic disorders because of the limitation of enzyme replacement or gene therapy. In this study, we report our single center experience about HSCT in several genetic metabolic disorders. Methods: We performed 6 cases of HSCT for genetic metabolic disorders from December 1999 to March 2001. Patients' diagnoses were Hunter syndrome (3), galactosialidosis (1), metachromatic leukodystrophy (1), and adrenoleukodystrophy (1). Stem cell sources were bone marrow from HLA matched sibling donors in 5 patients and mother's peripheral blood stem cells in one patient who did not have HLA matched donors. Busulfan and cyclophosphamide for conditioning, and cyclosporine for the prevention of graft versus host disease were used in all patients. Transplanted total nucleated cell counts were median 4.81×10^(8)(2.40~7.01×10^(8))/kg , and CD34+ cells 3.65×10^(6)(0.88~10.72×10^(6))/kg. Results: All patients achieved early hematologic recovery (median 9.5 days, range 9~14 days for ANC>500/μL; median 32 days, range 23~34 days for PLT>50,000/μL). Transplant-related complications were 3 cases of grade 1 acute GVHD, a case of limited chronic GVHD, and a case of mild hepatic veno-occlusive disease. Enzyme levels were normalized in 4 patients evaluated and there were indirect evidences of enzyme production in the other 2 patients after HSCT. Four of the 6 patients showed symptomatic improvement, 1 patient (galactosialidosis) experienced disease stabilization without progression before he eventually died due to pulmonary hemorrhage, and the other 1 patient deteriorated progressively even after HSCT. Conclusions: Allogeneic HSCT can be done as the only curative treatment in a number of genetic metabolic disorders. It seems desirable to perform HSCT as early as possible before the onset of central nervous system symptoms. More experience and long term follow up is needed to evaluate the efficacy and to monitor the long term transplant-related complications.
Effect of Low Temperature Annealing on ITO-on-Si Schottky Junction
Yoo, Keon,Lee, Jong-Ho IEEE 2017 IEEE electron device letters Vol.38 No.4
<P>In this letter, we investigate electrical properties of the indium-tin oxide (ITO)-on-Si Schottky junctions and the effect of a low temperature annealing on the properties. The ITOfilms are depositedbyRFmagnetronsputtering on n-type and p-type crystalline Si wafers. By measuring current-voltage and capacitance-voltage characteristics, it is foundthat a layerof positivefixedcharge is formedat the interface between the ITO and the Si by sputtering damage and that the charge layer distorts the barrier height of the ITO-on-Si junction. The low temperature annealing makes the ITO on p-and n-Si junctions ohmic-like and rectifying, respectively, by changing the barrier height.</P>